Fluvial systems and their sedimentary models

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Dragomir Skabeme

1995-12-01

Full Text Available The Slovenian géomorphologie and sedimentologie terminology for fluvial depositional environments is not established yet. Therefore a classification and the proposal for Slovenian names of fluvial sedimentary and erosional forms and influences controlling them are discussed. Attention is given to the problems of recognition of sedimentary environments in sedimentary rocks, and to fluvial sedimentary models.

Ecologia da vegetação de orla de bosque de carvalho-negral na Serra da Nogueira, Bragança, Portugal

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Rocha, S.; Aguiar, Carlos; Azevedo, João

2006-01-01

Avaliou-se o efeito do gradiente "distância à orla" na estrutura e composição florística de dois bosques de Quercus pyrenaica na Serra da Nogueira, Bragança, Portugal. Em cada bosque estabeleceram-se 8 transectos de 40 m com início na orla do bosque e orientados perpendicularmente a esta. Em cada transecto estabeleceram-se bandas de amostragem de 1 x 10 m dispostas perpendiculares aos transactos a 0, 1, 5, 10,20 e 40 m da orla do bosque. Nestas bandas avaliaram-se a composição flo...

Aves y endemismo en los bosques relictos de la vertiente occidental andina del norte del Perú y sur del Ecuador

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Jeremy N. M. Flanagan

2013-05-01

Full Text Available Los bosques relictos de las vertientes occidentales de los Andes del norte del Perú y el sur del Ecuador forman parte de dos regiones, una la denominada región de endemismo tumbesina (caracterizada principalmente por bosques secos y otra, en altitudes mayores, la región de endemismo del sur de los Andes centrales (caracterizada por bosques nublados y páramo. La región tumbesina es reconocida por albergar gran cantidad de aves endémicas, muchas de las cuales están amenazadas, y también por el alto grado de deforestación y fragmentación de sus hábitats naturales. Este artículo presenta un resumen del estado de conservación de dichas aves y bosques, con recomendaciones para mejorar la conservación de los últimos bosques de la vertiente occidental.

Biomasa de raíces en un bosque templado con y sin manejo forestal en Hidalgo, México

OpenAIRE

Pavón, Numa P.; Moreno, Claudia E.; Ramírez-Bautista, Aurelio

2012-01-01

Las raíces son buenos indicadores funcionales del ecosistema ya que constituyen gran parte de la biomasa viva del suelo y ejercen un control sobre los procesos de pedogénesis, la producción de materia orgánica y la dinámica de los nutrientes. En este trabajo se comparó la biomasa de raíces gruesas y finas entre un bosque conservado y un bosque con manejo forestal de corte selectivo. La biomasa promedio de raíces no difirió significativamente entre sitios (P = 0.185). La biomasa en el bosque c...

RELACION BOSQUE COMUNIDAD: ESTUDIO DE CASO VEREDA CLARETE ALTO, MUNICIPIO DE POPAYÁN

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JUAN PABLO PAZ-CONCHA

Full Text Available Con el propósito de conocer acerca de los procesos de organización comunitaria y de las relaciones de los habitantes de la Vereda Clarete con los bosques de roble (Quercus humboldtii, se realizaron talleres móviles, así como ejercicios de diagnostico rural rápido, que permitieron la participación activa de un grupo de personas de la comunidad bajo el acompañamiento de los profesores y la observación de estudiantes de la Universidad del Cauca. Estas actividades se integraron a un ejercicio de caracterización forestal y de la entomofauna asociada a estos ecosistemas. Se lograron establecer las relaciones que tienen los integrantes de la comunidad con el bosque, estableciendo la visión de hombres, mujeres y niños con respecto a los recursos naturales de la zona; de igual manera se establecieron los diferentes usos que tiene el bosque, entre los que se destacaron la leña, madera para construcción, postes para cercos, plantas medicinales y animales de caza.

Importancia económica de los bosques

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Yolanda Chamberlain

2011-09-01

Full Text Available En la actualidad, la población mundial ha adquirido mayor conciencia sobre la importancia de los bosques y su relación con la calidad de vida de las personas. A pesar de lo anterior, la tala indiscriminada continúa y se siguen realizando proyectos que afectan la flora y la fauna de las selvas, sobre todo, en los países menos desarrollados que explotan estos recursos como materia prima.En Costa Rica se ha tratado de mantener cierto control sobre los bosques. Por ejemplo, el 16 de abril de 1996 se publicó en el Diario Oficial La Gaceta, la Ley Forestal No.7575. Dicha Ley dispone una serie de medidas para la conservación de las áreas de protección y de reserva forestal. En el primer caso, se estipulan las distancias requeridas para la protección de las nacientes permanentes, las riberas de ríos, las quebradas o arroyos, las riberas de los lagos y los embalses naturales, las áreas de recarga acuífera y otros. En estas áreas, por ejemplo, no se podrá realizar ningún tipo de construcción ni autorizarse la tala de árboles.

The Gediz River fluvial archive

NARCIS (Netherlands)

Maddy, D.; Veldkamp, A.; Demir, T.; Gorp, van W.; Wijbrans, J.R.; Hinsbergen, van D.J.J.; Dekkers, M.J.; Schreve, D.; Schoorl, J.M.; Scaife, R.

2017-01-01

The Gediz River, one of the principal rivers of Western Anatolia, has an extensive Pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of Asia during the Quaternary. In this paper we review our work on the Quaternary Gediz River

Measuring variability in trophic status in the Lake Waco/Bosque River Watershed

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Rodriguez Angela D

2008-01-01

Full Text Available Abstract Background Nutrient management in rivers and streams is difficult due to the spatial and temporal variability of algal growth responses. The objectives of this project were to determine the spatial and seasonal in situ variability of trophic status in the Lake Waco/Bosque River watershed, determine the variability in the lotic ecosystem trophic status index (LETSI at each site as indicators of the system's nutrient sensitivity, and determine if passive diffusion periphytometers could provide threshold algal responses to nutrient enrichment. Methods We used the passive diffusion periphytometer to measure in-situ nutrient limitation and trophic status at eight sites in five streams in the Lake Waco/Bosque River Watershed in north-central Texas from July 1997 through October 1998. The chlorophyll a production in the periphytometers was used as an indicator of baseline chlorophyll a productivity and of maximum primary productivity (MPP in response to nutrient enrichment (nitrogen and phosphorus. We evaluated the lotic ecosystem trophic status index (LETSI using the ratio of baseline primary productivity to MPP, and evaluated the trophic class of each site. Results The rivers and streams in the Lake Waco/Bosque River Watershed exhibited varying degrees of nutrient enrichment over the 18-month sampling period. The North Bosque River at the headwaters (NB-02 located below the Stephenville, Texas wastewater treatment outfall consistently exhibited the highest degree of water quality impact due to nutrient enrichment. Sites at the outlet of the watershed (NB-04 and NB-05 were the next most enriched sites. Trophic class varied for enriched sites over seasons. Conclusion Seasonality played a significant role in the trophic class and sensitivity of each site to nutrients. Managing rivers and streams for nutrients will require methods for measuring in situ responses and sensitivities to nutrient enrichment. Nutrient enrichment periphytometers show

ESTRUCTURA, RIQUEZA Y COMPOSICIÓN DE PLANTAS ARBORESENTES EN UN BOSQUE DE NIEBLA ENTRESACADO DEL TOLIMA (COLOMBIA

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Juan Manuel Campo Kurmen

2010-05-01

Full Text Available RESUMEN Se presenta el estudio de la estructura, la riqueza y la composición florística del componente arborescente de un bosque entresacado, en la vereda Dantas, municipio de Ibagué, Tolima, Colombia, con base en el muestreo de los individuos con DAP ≥ 2,5 cm en 0,1 ha. El bosque se caracteriza por la escasez de lianas y de hemiepífitas, ausencia de familias típicas de bosques de niebla colombianos entre los 2000 y 2500 msnm (Ericaceae, Myrtaceae, Meliaceae y Aquifoliaceae y por un incremento en la riqueza de familias como Sabiaceae y Euphorbiaceae. Comparado con otros bosques de niebla de los Andes colombianos y del neotrópico, éste presenta una de las más bajas densidades de tallos (237 individuos con  DAP ≥ 2,5 cm por 0,1 ha y una proporción de árboles grandes muy alta (39,7% individuos con DAP ≥ 10 cm por 0,1 ha. Aparentemente, los efectos de la extracción selectiva de maderas sobre la riqueza, la estructura y la composición, fueron la disminución de la riqueza florística, del número de tallos del bosque, y de la densidad y la riqueza de lianas, así como un aumento en la densidad de especies secundarias como Hedyosmum goudotianum Slms-Laubach var. goudatianum, Miconia resima Naud. y Palicourea calophlebia Standl.

Deterioro y conservación de los bosques del Nevado de Toluca y el rol de los actores locales

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Ángel Rolando Endara Agramont

2016-01-01

Full Text Available El Área de Protección de Flora y Fauna Nevado de Toluca presenta una constante fragmentación de sus bosques. El objetivo de la investigación fue identificar los procesos de deterioro de sus bosques y el rol de los actores locales en su conservación. Se utilizaron los sistemas de información geográfica como base para la generación de mapas temáticos, además de la aplicación de un diagrama de flujo que define los problemas del bosque y otro que los describe y analiza para la búsqueda de soluciones. Los resultados muestran que los principales factores que inciden en el deterioro son incendios forestales, tala inmoderada, plagas y enfermedades. Finalmente se plantean estrategias y escenarios de manejo de los bosques a partir de la articulación de los actores locales.

Snake, rattle, and roll: Investigating the snakes that live in the Bosque along the Middle Rio Grande

Science.gov (United States)

Heather Bateman; Alice Chung-MacCoubrey; Deborah Finch

2010-01-01

After an area has been changed by human or natural disturbances, forest managers often engage in restoration activities. In the Bosque, fire is both a human and a natural disturbance. This is because most fires in the Bosque are started by humans. Restoration activities are things that forest managers do to the land to help an area resemble how it functioned in the...

COMPOSICIÓN FLORÍSTICA Y ESTRUCTURA DE LOS BOSQUES RIBEREÑOS DE LA CUENCA BAJA DEL RÍO PAUTO, CASANARE, COLOMBIA

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Diego Mauricio Cabrera-Amaya

2016-01-01

Full Text Available Se caracterizó la composición florística y aspectos de la estructura de la vegetación en bosques ribereños de la cuenca baja del río Pauto (Colombia, Casanare utilizando la información de nueve parcelas de 20 x 50 m (1000 m², se midieron el diámetro a la altura del pecho (DAP, la altura total y cobertura de la copa. Se analizó la riqueza y los valores de importancia por especie y por familia. Se realizó un análisis para establecer una clasificación local de los tipos de bosque, los cuales se describieron en términos de clases diamétricas y altimétricas, diagramas estructurales e índice de predominio fisionómico. Se registraron 185 especies, 127 géneros y 56 familias, la mayor riqueza florística se agrupó en las familias Rubiaceae, Moraceae, Myrtaceae, Fabaceae y Bignoniaceae y en los géneros Ficus, Piper, Psychotria e Inga. Las familias con mayor IVF fueron Arecaceae, Fabaceae, Euphorbiaceae, Moraceae y Verbenaceae. Las especies más importantes según su IVI fueron: Attalea butyracea, Clarisia biflora, Sarcaulus brasiliensis, Dendropanax arboreus e Inga interrupta. Se encontraron seis comunidades, de las cuales sólo la primera se ha mencionado con anterioridad: 1 Palmar de Mauritia flexuosa y Euterpe precatoria, 2 Bosque de galería de Copaifera pubiflora y Homalium racemosum, 3 Bosque de vega de Discocarpus spruceanus y Sloanea terniflora, 4 Bosque de vega de Attalea butyracea y Garcinia madruno, 5 Bosque de galería de Attalea butyracea e Inga interrupta, y 6 Bosque de vega Attalea butyracea y Clarisia biflora. Los bosques presentan múltiples estratos con alturas del dosel desde los 18 m sobre las riberas de los caños, hasta 25 m en las vegas de los ríos. La riqueza y la composición concuerdan con los patrones florísticos de la Orinoquía colombiana, especialmente a nivel de familia, pero son menos las coincidencias a nivel de género y especie. La concentración de individuos en clases diamétricas pequeñas es

DOMINANCIA FLORÍSTICA Y VARIABILIDAD ESTRUCTURAL EN BOSQUES DE TIERRA FIRME EN EL NOROCCIDENTE DE LA AMAZONÍA COLOMBIANA

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DUQUE ÁLVARO

2003-06-01

Full Text Available Se presenta un estudio de la vegetación en 3.1 ha de bosque distribuidos en 3 unidadesfisiográficas: coluvios derivados de superficies de areniscas, superficies terciarias y superficiesaluviales de origen de ríos amazonenses, en un área ubicada entre el río Yarí y el sectorsuroriental de la serranía de Chiribiquete, departamento de Caquetá, Amazonía colombiana.El número de especies de plantas vasculares con DAP > 10 cm en parcelasde 0.1 ha osciló entre 25 y 60, mientras que la diversidad (número de especies/número deindividuos varió entre 0.31 y 0.94. Mediante un análisis de componentes principales se identificarontres tipos estructurales de bosque, pero sin una clara relación con la variabilidadfisiográfica en el área. Oenocarpus bataua y Clathrotropis macrocarpa fueron las especiesmás abundantes en todas las unidades fisiográficas. De acuerdo con el análisis de coordenadaspolares, las superficies terciarias y las superficies aluviales de ríos de aguas oscuras,fueron entre sí similares florísticamente, mientras que los coluvios de las mesas deareniscas muestran una ligera tendencia hacia una mayor disimilitud florística. Seconcluye que los bosques de la Amazonía colombiana son tan ricos en especiescomo los registrados en la Amazonía ecuatoriana y peruana, aunque se aprecia unaclara diferencia florística entre los bosques de tierra firme del piedemonte amazónicoen Ecuador y Perú, y los bosques del norte de la Amazonía colombiana. Los resultadosde este estudio apoyan la idea de que la especialización edáfica de las especiesarbóreas en bosques de tierra firme bien drenada en la Amazonía noroccidental es muy baja.

Pasado, Presente y Perspectiva de Manejo de los Bosques de Guandal del Litoral Pacífico Colombiano

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Del Valle Arango Jorge Ignacio

1989-06-01

Full Text Available Se hace una descripción y análisis de lo que ha sido la explotación de los recursos naturales renovables de los bosques de la Costa Pacifica colombiana desde 1850 hasta hoy y en especial de los ciclos del caucho negro (Castilla elástica, la tagua (Phytelephas sp, el mangle (Rhizophora brevistila y las maderas, así como de la palma naidi (Euterpe oleracea que recién se inicia. El análisis se particulariza para los bosques de guandal donde se evidencia el decaimiento de la producción maderera y el riesgo de que la producción de naidí corra la misma suerte de los recursos que decaen o ya se extinguieron en su aporte económico. El autor encuentra elementos por afirmar que los corteros son verdaderos campesinos silvicultores, con evidencias en la región de rendimientos sostenidos en maderas y otros bienes y servicios en los mismos predios, que se remontaran hasta 50 años. Basándose en esta evidencia propugna porque se les reconozca la propiedad sobre la tierra y sus bosques. Finalmente, se hacen consideraciones técnicas que sugieren la viabilidad de un sistema silvicultural para estos bosques.

Distribución espacial del Bosque Seco Tropical en el Valle del Cauca, Colombia

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Diana Patricia Alvarado-Solano

2015-09-01

Full Text Available En el departamento del Valle del Cauca, la distribución de Bosque Seco Tropical (BsT se ha asociado al valle geográfico del río Cauca ubicado en la zona plana. Actualmente en esta zona, su cobertura se ha reducido a pocos relictos que se encuentran bajo alguna figura de conservación y mantienen áreas representativas de las formaciones vegetales sssstípicas de este bioma. Este trabajo se enfocó en el reconocimiento de la distribución espacial de formaciones vegetales de BsT en el departamento del Valle del Cauca. Se empleó información cartográfica secundaria para reconocer los biomas, ecosistemas y usos del suelo del área de estudio y en zonas adyacentes del piedemonte y montañas. Un modelo digital de elevaciones fue utilizado para realizar análisis altitudinales. En un sistema de información geográfico se aplicaron técnicas de geoprocesamiento y análisis geoespacial entre la información cartográfica y satelital. Los resultados evidencian que pese al avanzado deterioro de las coberturas de bosque seco en la zona plana, alrededor del 80 % se localiza en ecosistemas de montaña, específicamente en zonas de transición hacia bosques húmedos. A futuro, el potencial de estas áreas deberá evaluarse para ser incluidas en estrategias de conservación y restauración del bosque seco así como en el diseño de procesos adaptativos frente al cambio climático.

Generación del plan de manejo ambiental del Bosque Protector Aguarongo a partir de la evaluación de impacto ambiental

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Lomas Taipe, Martha Elizabeth

2016-01-01

El documento consiste en la generación de un plan de manejo ambiental del Bosque Protector Aguarongo a partir de la Evaluación de Impacto Ambiental, con la finalidad de identificar los impactos ambientales que se están efectuando dentro del bosque, para el planteamiento de programas y medidas que permitan la protección y conservación de la biodiversidad presente en el Bosque Protector Aguarongo. The document consists of the generation of an environmental management plan Protected Forest Ag...

Caracterización de hábitat y abundancia local de Dynastes hercules (Coleoptera: Melolonthidae: Dynastinae en bosques subandinos del departamento de Santander, Colombia

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Luisa Fernanda Ballesteros Mesa

2006-01-01

Full Text Available Se realizó una caracterización del estrato arbóreo de dos bosques subandinos con antecedentes de colecta del escarabajo hércules, Dynastes hercules, para estudiar la  condición de su hábitat y cuantificar la abundancia local. Se identificaron dos tipos de bosques correspondientes a robledal y selva de lauráceas; el estado de conservación del primer tipo de bosque es óptimo, teniendo en cuenta la densidad y buena oferta de árboles, troncos caídos en descomposición, flores y frutos. La abundancia de D. hercules fue mayor en el bosque de lauráceas debido a la baja presión de extracción de escarabajos en comparación con la población del bosque de roble. Por otro lado, los datos de abundancia de adultos obtenidos en el presente estudio no concuerdan con las estimaciones realizadas en trabajos similares.

Dinámica de la biomasa aérea en un bosque pluvial tropical del chocó biogeográfico.

OpenAIRE

Quinto Mosquera, Harley; Moreno Hurtado, Flavio

2012-01-01

El estudio de la biomasa aérea (BA) de los bosques tropicales es fundamental para entender el balance del C global en el contexto del cambio climático. La BA se cuantificó en un bosque maduro de Salero (Chocó Biogeográfico), mediante ecuaciones diseñadas para bosques húmedos tropicales, a partir de datos de densidad de madera, diámetro (DAP) y altura de árboles (con DAP ≥ 10 cm) medidos en dos sub-parcelas permanentes (“E” y “U”) de 1 ha, las cuales se monitorearon en los años 1998, 2005 y 20...

Diversidad y dinámica de un bosque subandino de altitud en la región norte de los Andes colombianos

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Jesús Oswaldo Velásquez Restrepo

2012-06-01

Full Text Available Los bosques sub-Andinos poseen alta diversidad biológica, de los cuales poco se conoce sobre su dinámica natural. Se evaluaron patrones de diversidad y biomasa, tasas de mortalidad y reclutamiento en dos parcelas permanentes de una hectárea cada una, establecidas en bosques en altitudes entre los 2 000-2 200msnm, en la vertiente Oriental de la cordillera Occidental del norte de los Andes en Colombia. Se determino diversidad de especies mediante el índice alpha de Fisher, la dinámica del bosque se evaluó mediante tres censos durante nueve anos. En total, se hallaron 1 964 individuos con un diámetro a la altura del pecho DAP≥10cm. pertenecientes a 222 especies, 113 géneros y 60 familias. La riqueza media de especies fue de 156 especies por hectárea y un índice alpha medio de Fisher de 56.2/h. Las tasas de mortalidad y reclutamiento fueron de 0.88% y 1.16% respectivamente, lo cual no indica que se presente un efecto externo proveniente del calentamiento global sobre la dinámica del bosque. La biomasa aérea promedio fue de 243.44±9.82tn/ha con un incremento anual promedio de 2.9ton/ha, valor superior a los reportados, lo cual sugiere que el equilibrio para este bosque no se ha alcanzado. De acuerdo con las observaciones de campo, este bosque parece estar recuperándose de una alteración pasada.

Diversidad preliminar de Artrópodos en los remanentes de bosques secos andinos del Valle del Chota en el norte del Ecuador

OpenAIRE

Troya, Adrián; Bersosa, Fabián; Vega, Mauricio

2012-01-01

En este artículo se da a conocer sobre los bosques secos que representan el 42% de todos los bosques tropicales y se encuentran en peligro de destrucción. Las investigaciones en los bosques secos de Ecuador son puntuales en aspectos botánicos y ecológicos. Durante la época seca se muestreó dos localidades en el Valle del Chota con el objetivo de conocer la diversidad de artrópodos terrestres. Se colectaron 282 morfo-especies pertenecientes a 128 familias de artrópodos correspondientes a 22 ór...

Estudios de la comunidad de coleópteros coprófagos (Scarabaeidae en un remaente de bosque seco al norte del Tolima, Colombia

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Escobar S. Federico

1997-11-01

Full Text Available This paper presents information about the dung beetle community in altered landscapes in northern Tolima, Colombia. The studies were carried out in hill forest, creek forest, forest edge and pastures in the dry season, and in hill forest and creek forest in the rainy season. 3538 inividuals of 30 species in 4 subfamilies were captured. Changes in the species abundance between sampling periods were found. Differences in species composition between zones with forest cover and pasture were recorded, as well as changes in the guild structure, with endocoprids prevailing in pasture and edge habitats.Se presenta información sobre la comunidad de coleópteros coprófagos en un remanente de bosque seco al norte del Tolima, caracterizado por una alta transformación del paisaje. Se realizó un muestreo en la época seca y otro en época lluviosa; en la época seca se realizaron colecciones en bosque de cerro, bosque de cañada, borde de bosque y potrero, en la época lluviosa en bosque de cañada y bosque de cerro. Se capturaron un total de 3538 individuos pertenecientes a 30 especies en 4 subfamilias. Se registraron cambios en la abundancia de las especies entre los períodos de muestreo y en la composición de especies entre zonas con cobertura boscosa y potreros. También se detectaron cambios en la estructura de los gremios, observándose un incremento de las especies de hábitos endocópridos en el borde de bosque y en potrero.

Montes y bosques de Orihuela en los siglos XVI y XVII

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José Ojeda Nieto

2007-01-01

Full Text Available Los montes y los bosques de la época Moderna son poco conocidos. Escasean los documentos, y cuando los hay se fijan en las talas y abusos cometidos por los vecinos o en las preocupaciones -normativas concejiles- de buena utilización de la leña y la madera. La Orihuela foral, siglos XVI y XVII, gozaba de una amplia extensión de terrenos comunales donde el pastoreo convivía con el aprovechamiento silvícola. El presente estudio marca los límites del monte, concretamente del arbolado, al tiempo que cuantifica, como propuesta, los distintos espacios que configuraban el paisaje del Bajo Segura: huerta, boalares, redondas y realengo. Normas y leyes que reglamentaban cortes y talas, así como los malos usos del bosque -carboneo e incendios-, son también analizados para entender el proceso de deforestación y su control a lo largo de las citadas centurias.

Los trabajadores subcontratistas de Bosques Arauco y CODELCO: ¿Un movimiento en vías de politización?

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Claudia Jordana Contreras

2009-01-01

Full Text Available Uno de los principales problemas que atraviesa la sociedad actual es la despolitización. Los movimientos de los trabajadores subcontratistas de CODELCO y Bosques Arauco, sin embargo, parecen oponerse a esa tendencia. En esta investigación se estudia, precisamente, si eso es así, es decir, si estos movimientos son susceptibles de ser analizados desde un punto de vista político; si tienen posibilidades de proyectarse en el tiempo o si sus demandas y reivindicaciones son más bien coyunturales. Los principales resultados nos indican que hay distintos grados de politización en los movimientos de CODELCO y de Bosques Arauco. Las posibilidades de proyectarse políticamente del movimiento subcontratista de CODELCO son mayores que las de Bosques Arauco.

Fluvial geomorphology on Earth-like planetary surfaces: A review.

Science.gov (United States)

Baker, Victor R; Hamilton, Christopher W; Burr, Devon M; Gulick, Virginia C; Komatsu, Goro; Luo, Wei; Rice, James W; Rodriguez, J A P

2015-09-15

Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn's moon Titan). In other cases, as on Mercury, Venus, Earth's moon, and Jupiter's moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn's moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry.

Titan's fluvial valleys: Morphology, distribution, and spectral properties

Science.gov (United States)

Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, Christophe; Barnes, J.W.; Nelson, R.

2012-01-01

Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2

Ecología de la dispersión de plantas en los bosques secos del suroccidente Ecuatoriano

OpenAIRE

Jara Guerrero, Andrea Katherine

2014-01-01

La importancia del proceso de dispersión de semillas en la estructura y dinámica de los ecosistemas es ampliamente reconocida. Sin embargo, para los bosques tropicales estacionalmente secos los estudios relacionados con este proceso son aún escasos y dispersos en comparación con los bosques tropicales lluviosos. En este trabajo se estudió la importancia de los síndromes de dispersión de semillas en la estructuración de comunidades, mediante el análisis de los patrones de dispersión de semilla...

Reconstrucción del límite superior del bosque en la parte norte del Ecuador: algunos resultados del proyecto RUFLE

NARCIS (Netherlands)

Sevink, J.; Tonneijck, F.; Jansen, B.; Hooghiemstra, H.; Cuesta, F.; Sevink, J.; Llambí, L.D.; De Bièvre, B.; Posner, J

2014-01-01

Resumen Se estudiaron los suelos, los registros de polen y los marcadores biológicos en transectos entre bosque y páramo en la reserva natural Guandera al norte del Ecuador para reconstruir el límite superior del bosque y establecer sus características y dinámicas. Se encontró que los suelos estaban

Vision for a worldwide fluvial-sediment information network

Science.gov (United States)

Gray, J.R.; Osterkamp, W.R.

2007-01-01

The nations of the world suffer both from the deleterious effects of some natural and human-altered fluxes of fluvial sediment and a lack of consistent and reliable information on the temporal and spatial occurrence of fluvial sediments. Decades ago, this difficulty was unavoidable due to a lack of understanding of the magnitude and scope of environmental influences exerted by fluvial sediment coupled with a dearth of tools for monitoring and studying the data. Such is no longer the case.

TEORIA SOCIAL E MEIO AMBIENTE: REFLEXÕES A PARTIR DAS MOTIVAÇÕES DE CONSTITUIÇÃO DE UM BOSQUE URBANO

Directory of Open Access Journals (Sweden)

Felipe Bueno Amaral

2015-12-01

Full Text Available Este artigo se insere nas reflexões socioambientais contemporâneas que partem das contribuições da teoria da ação e da racionalidade desde Max Weber. Neste estudo nos debruçamos no processo de constituição de um bosque urbano dentro de uma região de casas de alto padrão, de um pequeno município da região metropolitana de Curitiba, PR, com interesse de perseguir e compreender as motivações desta constituição. Com esse intento, a pesquisa foi realizada num período de dois meses, onde frequentamos o bosque e entrevistamos a comunidade do entorno e também os organismos da prefeitura do município, relacionados a construção e manutenção de parques, praças e bosques. Foi possível perceber que dentre as múltiplas motivações da constituição do bosque estudado, a principal delas resultou de um conflito social entre dois grupos, entre indivíduos que utilizavam o bosque de modo distinto. Através disso constatou-se que as noções de natureza e meio ambiente, estão diminuídas ante outras noções como segurança e legislação, e sobretudo, que o meio ambiente não está descolado das ações dos indivíduos.

Efectos negativos de las plantas exóticas maderables sobre el bosque nativo andino

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Fidel Antonio Gutiérrez

2011-07-01

Full Text Available Los abusos que el hombre ha cometido con la naturaleza han provocado que muchas áreas, que debían ser santuarios vegetales, padezcan el deterioro del bosque nativo, con el consiguiente daño ambiental, hídrico, de flora y fauna. No escapa a ello la Escuela Nacional de Carabineros, pues su cerro tutelar fue sometido a una plantación de árboles exóticos maderables, con la consabida tala del bosque nativo. Los daños en dicho cerro han provocado la implementación de una reforestación técnica, que permita devolver la dinámica propia a la vegetación nativa, lo cual debe dar como resultado un Plan Estratégico de Manejo Ambiental, para futuras aplicaciones.

Patrones de distribución de especies arbóreas de dosel y sotobosque a escala local en bosques de tierra firme, Amazonia colombiana

OpenAIRE

Juan Sebastian Barreto-Silva; Dairon Cárdenas López; Álvaro Javier Duque Montoya

2014-01-01

El efecto de la variación ambiental en la estructura de las comunidades arbóreas en bosques tropicales, aún se debate. En paisajes como los bosques de tierra firme, donde el gradiente ambiental disminuye, el efecto de los suelos sobre los patrones de distribución de especies es mínimo. En contraste, un mayor efecto de la variación edáfica y topográfica sobre la composición florística, se ha reportado en estudios con diferentes tipos de plantas en bosques tropicales. Este estudio se realizó en...

RESPIRACIÓN, BIOMASA MICROBIANA Y ACTIVIDAD FOSFATASA DEL SUELO EN DOS AGROECOSISTEMAS Y UN BOSQUE EN TURRIALBA, COSTA RICA

Directory of Open Access Journals (Sweden)

Wuellins Durango

2015-01-01

Full Text Available Con el fin de evaluar algunas característi - cas microbiológicas y bioquímicas, se realizó un estudio comparativo entre 3 sistemas de manejo del suelo en Ultisoles, ubicado en Grano de Oro, Turrialba Costa Rica. Se eligieron 3 sistemas de manejo de suelos (2 agroecosistemas, café y café- banano y bosque. En cada finca se colectaron 4 muestras compuestas de suelo, a las cuales se les determinó respiración, biomasa microbiana y actividad de la enzima fosfatasa. En los suelos del bosque la biomasa microbiana fue estadísti - camente superior (423 mg C kg -1 comparada con la de los agroecosistemas café y café-banano (77 y 111 mg C kg -1 respectivamente. La respiración microbiana no presentó diferencias (580, 560 y 570 μg CO 2 g -1 .día -1 en los sistemas café, café- banano y bosque, respectivamente. También se determinó que la actividad de la enzima fosfatasa en los suelos del bosque fue estadísticamente más alta (4432 μg p-NP g -1 .h -1 . Los resultados sugieren que las condiciones del suelo en el bos - que favorecen una mayor biomasa microbiana y mayor actividad de la fosfatasa, comparados con los sistemas agrícolas.

A fluvial mercury budget for Lake Ontario.

Science.gov (United States)

Denkenberger, Joseph S; Driscoll, Charles T; Mason, Edward; Branfireun, Brian; Warnock, Ashley

2014-06-03

Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition.

Buscando la Historia en los Bosques: el papel de los macrovestigios y de la vegetación en la Mata Atlántica

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Adi Estela Lazos Ruíz

2017-04-01

Full Text Available El paisaje de hoy es un reflejo de usos sobrepuestos a lo largo del tiempo, cada época va dejando huellas. Los bosques suelen tomar parte de esas transformaciones y están por lo tanto marcados por la historia. En este trabajo recopilamos evidencias de usos pasados dentro del bosque de Mata Atlántica del sureste brasileño a través de macrovestigios (e.g. ruinas, caminos antiguos, etc. y del estudio de la configuración de la vegetación (e.g. identificando especies y su estado sucesional. Utilizando la metodología de lectura del paisaje, asociamos estos elementos presentes en el bosque actual con su contexto histórico y ofrecemos una posible interpretación. De esta manera, los macrovestigios y la vegetación resultan ser particularmente útiles como “documentos” para los paisajes sin historia. El reconocimiento del valor histórico del bosque es importante para fortalecer la identidad de los pueblos y para incluirlo en medidas de gestión y conservación de los recursos.

Litterfall, litter decomposition and nitrogen mineralization in old-growth evergreen and secondary deciduous Nothofagus forests in south-central Chile Aporte, descomposición de hojarasca y mineralización de nitrógeno en bosques siempreverdes de antiguo crecimiento y bosques secundarios deciduos, centro-sur de Chile

Directory of Open Access Journals (Sweden)

JEROEN STAELENS

2011-03-01

mineralization rates in the present study.Los ecosistemas forestales del sur de Chile presentan un gran valor ecológico pues constituyen una de las mayores áreas del hemisferio Sur con existencias de bosques templados lluviosos. Están sometidos a procesos de deforestación, invasión de especies exóticas, fragmentación e incremento de depositación de nitrógeno (N atmosférico. Para apoyar su manejo sustentable se requiere de mayor conocimiento en el ciclo de nutrientes de estos ecosistemas. Se estudia la dinámica de nutrientes en cuatro sitios de bosques lluviosos valdivianos de la precordillera de los Andes, centro-sur de Chile: un bosque siempreverde de antiguo crecimiento prístino y otro alterado, un bosque caducifolio secundario con manejo silvícola y otro sin. Durante el período octubre 2002 -septiembre 2006, se estimaron (i masa de la hojarasca (cuatro años y contenido de nutrientes de la hojarasca (un año, (ii descomposición y dinámica de nutrientes de hojarasca (un año y de la corteza de Saxegothaea conspicua, y (iii mineralización neta de nitrógeno (N-min en el suelo in situ (un año. El aporte de hojarasca en los cuatro sitios fluctúa desde 3.5 hasta 5.8 ton ha-1 año-1, y es temporalmente menor en bosque caducifolio manejado, respecto del caducifolio sin manejo. Además, presentan una estacionalidad en los siempreverdes que es diferente, respecto de los deciduos. La hojarasca se descompone más rápidamente (promedio 32 % pérdida de masa después de un año que la corteza (8 %, pero no se presentaron diferencias significativas en la hojarasca. El N neto en la hojarasca de los bosques siempreverdes disminuye durante la descomposición, pero se incrementa en la hojarasca de los deciduos. La N-mineralización neta del suelo fue completa en el bosque siempreverde prístino, intermedia en los bosques deciduos y el más baja en el bosque siempreverde alterado. Dada la ausencia de réplicas en las parcelas, no puede ser demostrado el impacto definido del

Efecto de plantaciones de pino en la artropofauna del suelo de un bosque Altoandino

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Alba Lucía León-Gamboa

2010-09-01

Full Text Available Los artrópodos del suelo son un componente fundamental de los ecosistemas de bosque, ya que participan en la fragmentación de los residuos orgánicos previa a la descomposición. Esta función es más valuable en ambientes de altura, donde las bajas temperaturas limitan la dinámica de los procesos biológicos. Sin embargo, uno de los problemas más comunes en las montañas colombianas ha sido el reemplazo de vegetación nativa por plantaciones de pino. Los efectos sobre los artrópodos del suelo aún son poco conocidos. En un remanente de bosque Altoandino (Embalse del Neusa-Colombia con una plantación adyacente de unos 50 años (aprox. 900 has, fue evaluada la composición, riqueza y abundancia de artrópodos en los estratos superficial (S orgánico (O y mineral (A del suelo, para establecer las diferencias asociadas con la transformación del uso del suelo. Se utilizaron trampas "Pitfall" para registrar el movimiento de fauna epígea, y embudos Berlese para estimar la densidad de fauna de los horizontes O y A. Se calcularon los índices de Shannon y Simpson para estimar la diversidad en diferentes lugares y horizontes, además fue evaluada la estructura trófica de la comunidad. Se recolectaron 38 306 individuos en el bosque y 17 386 en la plantación, principalmente distribuidos en los taxa Collembola, (42.4%, Acari (27%, Diptera (17.6% y Coleoptera (4.6%. Las diferencias más importantes se dieron en la superficie, donde la movilización en bosque (86 individuos/día casi triplicó la movilización en la plantación (33 individuos/día. Las diferencias en la composición se dieron en los taxa Collembola, Araneae, Hemiptera, Homoptera e Hymenoptera. La dinámica de la riqueza y abundancia a lo largo del año tuvo picos significativos en el bosque, no observados en la plantación. La estructura trófica fue dominada por saprófagos (75%, depredadores (14% y fitófagos (9%, pero en dos estratos de la plantación de pino (S y O no se dio

Contribución de los bosques tropicales de montaña en el almacenamiento de carbono en Colombia

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Adriana Yepes

2015-03-01

Full Text Available Los bosques tropicales de montaña (BTM en la región Andina de Colombia se encuentran por encima de 1 500m, y han sido fuertemente deforestados. A pesar de la presunción general de que la productividad y las reservas de carbono en estos ecosistemas son bajas, los estudios al respecto son escasos. Este estudio tuvo por objetivo i estimar la biomasa aérea (BA de los bosques localizados en el sur de la región Andina colombiana, ii identificar el potencial de almacenamiento de carbono en bosques dominados por el roble negro Colombobalanus excelsa e identificar la relación entre la BA y la altitud, y iii analizar su papel en mecanismos de conservación, como el Pago por Servicios Ambientales (PSA y la Reducción de Emisiones por deforestación y Degradación (REDD+. Veintiséis parcelas de 0.25ha fueron distribuidas al azar, y se midieron todos los árboles con D≥10cm. Los resultados obtenidos de BA y carbono almacenado fueron similares a los reportados para bosques tropicales de tierras bajas. Esto se puede explicar por la abundancia y dominancia de C. excelsa, que contribuye con más del 81% de la BA/carbono; el error asociado a las estimaciones fue de 10.58%. Se encontró una relación negativa y significativa entre la BA y la altitud, pero los valores más altos de BA estuvieron en las altitudes medias (≈1 700-1 800m, donde las condiciones ambientales podrían ser favorables para su crecimiento. El potencial de almacenamiento de carbono de estos bosques fue alto. Los resultados permiten tener elementos importantes para entender el papel de los BTM como sumideros de carbono. Sin embargo, si la tasa histórica de deforestación en el área de estudio continúa, las emisiones brutas de CO2e a la atmósfera podrían convertirlos en una fuente de emisiones importante. Actualmente, los BTM son vulnerables a la deforestación, especialmente los bosques de roble negro debido a su valor comercial. Teniendo en cuenta el alto potencial de

Crecimiento anual de cuatro especies arbóreas con yemas desnudas nativas de los bosques templados húmedos de Patagonia

OpenAIRE

Sosa, Claudia M; Puntieri, Javier G

2016-01-01

Las especies vegetales que habitan en regiones con bajo nivel de estacionalidad en el clima suelen presentar rasgos morfo-arquitecturales que ocurren con menor frecuencia en especies de regiones con clima estacional. El objetivo de este estudio fue evaluar el crecimiento primario en vivero de cuatro especies leñosas típicas de los bosques templados húmedos de Patagonia, conocidos como selva valdiviana, donde el grado de estacionalidad es menos marcado que en otros bosques patagónicos. Las esp...

Pentimento: Fuels reduction and restoration in the Bosque of the Middle Rio Grande

Science.gov (United States)

Deborah M. Finch

2008-01-01

The Middle Rio Grande of New Mexico is the most extensive, remaining bosque, or cottonwood forest in the southwest. Alterations caused by humans-damming and channeling the river, controlling floods, and planting non-native trees-have disrupted the cycles of the earlier ecosystem. Without periodic flooding, native cottonwoods cannot regenerate. Invasive exotic plants...

Comparación de propiedades edáficas y procesos ecosistémicos entre plantaciones forestales y bosques secundarios subandinos

OpenAIRE

Gómez Sarmiento, Margarita

2011-01-01

Los cambios en la cobertura y uso del suelo tienen efectos importantes en el suelo y en las funciones ecosistémicas que este soporta. En este estudio se compararon algunas propiedades edáficas entre bosques secundarios subandinos y plantaciones forestales de pino y, dos procesos ecosistémicos: la productividad sobre el suelo y la descomposición. El estudio se realizó en la cuenca del río Otún (Risaralda). Se tomaron nueve muestras de suelo en bosque y nueve en plantaciones. Se determinó la de...

Insectos descortezadores (coleoptera: curculionidae) y cambio clImático: problemática actual y perspectivas en los bosques templados

OpenAIRE

Ek del-Val; Cuauhtémoc Sáenz-Romero

2017-01-01

En los bosques templados están sucediendo modificaciones importantes debido al cambio climático; en latitudes polares va en aumento su área de distribución, mientras que en las tropicales se reduce por incremento en la temperatura y las sequías. Uno de los agentes bióticos reguladores de los bosques templados son los insectos descortezadores que ocasionan la mortalidad de ciertos árboles. Estos insectos han aumentado en número, favorecidos por el cambio climático y las consecuencias sobre los...

Insectos descortezadores (coleoptera: curculionidae) y cambio clImático: problemática actual y perspectivas en los bosques templados

OpenAIRE

Ek del-Val; Cuauhtémoc Sáenz-Romero

2017-01-01

En los bosques templados están sucediendo modificaciones importantes debido al cambio climático; en latitudes polares va en aumento su área de distribución, mientras que en las tropicales se reduce por incremento en la temperatura y las sequías. Uno de los agentes bióticos reguladores de los bosques templados son los insectos descortezadores que ocasionan la mortalidad de ciertos árboles. Estos insectos han aumentado en número, favorecidos por el cambio climático y las consecuencias sobr...

Estudio preliminar de la composición de la comunidad de escarabajos coprófagos ( Coleptera: Scarabaeidae de un bosque altoandino en Albán (Cundinamarca, Colombia

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Héctor Jaime Gasca

2000-07-01

Full Text Available Los escarabajos coprófagos son un buen modelo para estudiar los cambios estructurales y composicionales que en la actualidad están ocurriendo en los bosques altoandinos. Los disturbios ocasionados sobre el bosque alteran notoriamente la composición de las especies que habitan allí. En el caso de los coleópteros estercoleros se presenta un impacto mayor ya que dependen directamente de los mamíferos allí existentes y estos a su vez son uno de los grupos animales más vulnerables a la perdida de bosques.

Field migration rates of tidal meanders recapitulate fluvial morphodynamics

Science.gov (United States)

Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

2018-02-01

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

MARCO CONCEPTUAL PARA PRODUCTOS NO MADERABLES DEL BOSQUE EN MANGLARES DE COLOMBIA

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García S. Catalina

2008-07-01

Full Text Available La política de bosques de la mayoría de países tropicales está dirigida inicialmente a la utilización de los recursos forestales para madera y, de forma secundaria, para leña. Sin embargo, los bosques tropicales generan otros productos que, en algunos países, pueden tener un alto valor, comparable con el de la madera, llamados “productos forestales menores” o “productos forestales no maderables” (‘PFNM’. Desafortunadamente, este rótulo no realza el hecho de que su aprovechamiento es una actividad importante en economías rurales. Los PFNM han suscitado interés por su contribución económica y social en muchos países, sobre todo para poblaciones rurales; en toda América Latina se aprovechan y, particularmente, en Colombia, es necesario reglamentar de forma clara y precisa su explotación. Aquí presentamos un marco conceptual para los PFNM en Colombia y describimos la contribución potencial de los manglares a este mercado.

Estimación de carbono almacenado en bosques de oyamel y ciprés en Texcoco, Estado de México

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Yunuen Bolaños González

2017-01-01

Full Text Available Las emisiones de carbono (C a la atmósfera, así como sus reservorios, en el sector de agricultura, silvicultura y otros usos del suelo son significativas en el balance global del ciclo del carbono; sin embargo, a pesar de esta importancia, es el sector con la mayor incertidumbre en el balance global debido principalmente a la falta de conocimiento preciso de los factores de emisión, por lo que se requiere mayor investigación en el tema. Debido a lo anterior, este trabajo tuvo como objetivo estimar el C almacenado en los cinco depósitos considerados en ecosistemas forestales: biomasa viva sobre el suelo, biomasa viva debajo del suelo, madera muerta sobre el suelo, mantillo y carbono orgánico del suelo (COS en dos sitios de muestreo ubicados en las faldas del Monte Tláloc, Texcoco, Estado de México: el primero en un bosque de oyamel (Abies religiosa y el segundo en un bosque de ciprés (Cupressus lusitanica. El promedio de la densidad de carbono en el bosque de oyamel en los cinco depósitos estimados fue de 376 Mg ha‑1, siendo el depósito más importante el de biomasa aérea (59%, seguido del COS (22%; en tanto que en el bosque de ciprés fue de 205 Mg ha-1, siendo el depósito con mayor densidad el COS (50%, seguido de biomasa aérea (36%. Los valores de densidad de carbono para biomasa aérea en el caso de bosque de oyamel fueron superiores a los reportados en otros trabajos; lo cual se explica por la existencia de árboles de grandes dimensiones de esta especie en el sitio de muestreo, lo cual nos da una idea precisa del potencial como almacén de carbono que este tipo de vegetación tiene cuando llegan a estados maduros.

The contribution of bank and surface sediments to fluvial sediment ...

African Journals Online (AJOL)

The contribution of bank and surface sediments to fluvial sediment transport of the Pra River. ... the relative contribution of surface and bank sediments to the fluvial sediment transport. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

Caracterización, distribución y manejo de los bosques nativos en el norte de Uruguay Characterization, distribution and management of native forests in northern Uruguay

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Ignacio P. Traversa-Tejero

2013-03-01

Full Text Available Los bosques del norte de Uruguay sufren de procesos de transformación del territorio y degradación, actualmente existe escasa información sobre la estructura y composición florística de las comunidades arbóreas que sirva como base para estudiar su dinámica. Se analizó la distribución, la composición arbórea y el manejo silvícola de los bosques de la región de Rivera, Uruguay. El área de estudio comprende 33 000 ha delimitadas mediante 2 criterios, uno natural (cuenca hidrológica y otro socioeconómico (ciudad de referencia. La información proveniente de inventarios florísticos y encuestas a productores fue ingresada a un sistema de información geográfica. Los bosques se agruparon de acuerdo al gradiente hídrico asociado con curvas de nivel. La superficie de los bosques ocupa el 13.9% del área de estudio (región de Rivera, cifra que triplica la superficie de bosques existente a nivel nacional. Se registraron 60 especies leñosas. Las familias con mayor frecuencia fueron Anacardiaceae (26.5% y Euphorbiaceae (14.7%. Las Anacardiaceae son más frecuentes en los bosques subxerófilos y las Euphorbiaceae en los bosques hidrófilos. Todos los bosques son vulnerables debido a la mayor importancia que se concede a la ganadería, sin que exista un manejo integrado de los bosques que contemple la multifuncionalidad de usos (silvicultura y ganadería. Los bosques cercanos a la ciudad están más degradados debido a la presencia de especies exóticas.The northern region of Uruguay undergoes land transformation processes, and degradation of native forest. The existing information on the structure and floristic composition of the forests in that region, as a basis for studies about dynamics, is scarce. Species distribution, floristic composition (wooden species and forest management, was assessed in the Rivera Region, Uruguay. The study area (33 000 ha was delimited by 2 simultaneous and complementary approaches, the first one natural

Dinámica de la biomasa aérea en bosques primarios de Colombia y su relación con la precipitación y la altitud

OpenAIRE

Quinto Mosquera, Harley

2010-01-01

El estudio de la biomasa aérea (BA) de los bosques tropicales es fundamental para entender el balance del C global en el contexto del cambio climático. La BA se cuantificó en un bosque primario de Salero (Chocó Biogeográfico), mediante ecuaciones diseñadas para bosques húmedos tropicales, a partir de datos de densidad de madera, diámetro (DAP) y altura de árboles (con DAP ≥ 10 cm) medidos en dos sub-parcelas permanentes (“E” y “U”) de 1 hectárea, las cuales se monitorearon en los años 1998, 2...

Comunidad de escarabajos copronecrófagos (Coleoptera: Scarabaeidae en dos bosques del Chaco Oriental Húmedo, Argentina

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Miryam P. DAMBORSKY

2008-01-01

Full Text Available Se investigó y comparó la estructura de la comunidad de Scarabaeinae en dos ambientes con distinto grado de conservación. Se efectuaron muestreos en un bosque nativo del Parque Provincial Pampa del Indio y en un fragmento de bosque del establecimiento ganadero Los Alisos. Los ejemplares se capturaron con coprotrampas y necrotrampas que permanecieron activas durante 72 horas, en los meses de octubre, noviembre y diciembre de 2006. Se colectaron 769 individuos adultos pertenecientes a seis tribus, 11 géneros y 26 especies. En Los Alisos Ontherus sulcatus Fabricius y Onthophagus hirculus Mannerheim resultaron dominantes. Trichillum sp., Canthon podagricus Harold, Malagoniella sp., Gromphas lacordairei Brullé, y dos especies de Dichotomius Hope fueron exclusivas de este establecimiento. Canthon septemmaculatus Latreille y Coprophanaeus jasius Olivier sólo se colectaron en Pampa del Indio. El número de individuos y la diversidad alcanzaron valores significativamente superiores en Pampa del Indio. En Los Alisos, se constató igual proporción de coprófagos y necrófagos, y una mayoría de especies con hábitos endocópridos y paracóprido En Pampa del Indio, se encontraron más especies de hábitos necrófagos y rodadores. La presente contribución constituye el primer estudio sobre la biodiversidad de Scarabaeinae en el ambiente de bosque de la provincia del Chaco.

Fluvial to Lacustrine Facies Transitions in Gale Crater, Mars

Science.gov (United States)

Sumner, Dawn Y.; Williams, Rebecca M. E.; Schieber, Juergen; Palucis, Marisa C.; Oehler, Dorothy Z.; Mangold, Nicolas; Kah, Linda C.; Gupta, Sanjeev; Grotzinger, John P.; Grant, John A., III;

Deposição e composição química de serrapilheira em um bosque de sabiá

OpenAIRE

Freire,Joelma de Lira; Dubeux Júnior,José Carlos Batista; Lira,Mario de Andrade; Ferreira,Rinaldo Luiz Caraciolo; Santos,Mércia Virginia Ferreira dos; Freitas,Erinaldo Viana de

2010-01-01

Objetivou-se avaliar a deposição e composição química de componentes da serrapilheira existente e depositada em um bosque de sabiá (Mimosa caesalpiniifolia Benth). O experimento foi realizado durante o período de agosto de 2006 a julho de 2007. A avaliação da serrapilheira existente e depositada foi realizada a cada 28 dias utilizando-se 20 quadrados de 1 m², alocados aleatoriamente, escolheno novas áreas a cada avaliação. O bosque apresentou plantas com diâmetro média na altura do peito de 2...

Evaluación de los bosques templados en México: una aplicación en el Parque Nacional Nevado de Toluca

OpenAIRE

Lourdes Villers Ruíz; Laura García del Valle; Jorge López Blanco

1998-01-01

Con base en un análisis de fotointerpretación y de evaluación botánica de sitios, se propone una metodología expedita que permita conocer las características generales de los bosques templados en México. La metodología fue aplicada en el parque nacional Nevado de Toluca. Se determinaron tres comunidades de bosque: a) de Pinus hartwegu. b) de Abies religiosa y c) mixto Abies religiosa. Alnas jorullensis, P pseudostrobus y P hartwegii Para cada comunidad se definieron por fotointerpretación tre...

DETERMINANTES DE LA COMPOSICIÓN FLORÍSTICA Y EFECTO DE BORDE EN UN FRAGMENTO DE BOSQUE EN EL GUAVIARE, AMAZONIA COLOMBIANA

OpenAIRE

Stevenson, Pablo R.; Rodríguez, María Elizabeth

2008-01-01

La fragmentación de un bosque genera cambios en muchos aspectos bióticos y abióticos de los parches remanentes. En este estudio se describe la composición florística de un fragmento de bosque en el departamento del Guaviare, Colombia, analizando el efecto de borde y factores abióticos. Se establecieron diez parcelas de 100 x 10 m y se muestrearon todas las especies de árboles con DAP≥ 10 cm. El índice de importancia mostró que las especies con mayores valores fueron Iriartea deltoidea, Croton...

Field migration rates of tidal meanders recapitulate fluvial morphodynamics.

Science.gov (United States)

Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

2018-02-13

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths. Copyright © 2018 the Author(s). Published by PNAS.

Fluvial hydrology and geomorphology of Monsoon-dominated Indian rivers

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Vishwas S. Kale

2005-11-01

Full Text Available The Indian rivers are dominantly monsoon rainfed. As a result, their regime characteristics are dictated by the spatio-temporal variations in the monsoon rainfall. Although the rivers carry out most of the geomorphic work during 4-5 months of the monsoon season, the nature and magnitude of response to variations in the discharge and sediment load varies with the basin size and relief characteristics. Large monsoon floods play a role of great importance on all the rivers. This paper describes the hydrological and geomorphological characteristics of the two major fluvial systems of the Indian region, namely the Himalayan fluvial system and the Peninsular fluvial system. Large number of studies published so far indicate that there are noteworthy differences between the two river systems, with respect to river hydrology, channel morphology, sediment load and behaviour. The nature of alterations in the fluvial system due to increased human interference is also briefly mentioned. This short review demonstrates that there is immense variety of rivers in India. This makes India one of the best places to study rivers and their forms and processes.

Los servicios ecosistémicos que ofrecen los bosques tropicales

OpenAIRE

P. Balvanera

2012-01-01

Los servicios ecosistémicos son los beneficios que las sociedades obtienen de los ecosistemas. Este concepto permite hacer más explícita la interdependencia del bienestar humano y el mantenimiento del adecuado funcionamiento de los ecosistemas. Los bosques tropicales del mundo, debido a su amplia distribución, elevada diversidad y contribución a funciones clave del planeta como la regulación climática e hidrológica proveen una serie de servicios ecosistémicos críticos. En este artículo se hac...

Dieta de Odocoileus virginianus (Artiodactyla: Cervidae en un bosque templado del norte de Oaxaca: México

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Graciela González

2012-03-01

Full Text Available La región de la Sierra Madre de Oaxaca, ubicada al norte del estado de Oaxaca, México, es una zona de ecosistemas con alta actividad forestal; en algunas áreas sus bosques templados son conservados por iniciativas de las comunidades indígenas que ahí habitan. Dentro de estos bosques, se analizó la dieta del venado cola blanca (Odocoileus virginianus en San Miguel Amatlán y Santa Catarina Lachatao entre junio 1998 y agosto 1999. Se utilizó el análisis microhistológico de heces fecales, la observación de rastros de ramoneo en plantas y el análisis de contenidos estomacales. La dieta anual estuvo constituida por 42 especies de 23 familias vegetales. Las familias con el mayor número de especies fueron: Fagaceae, Asteraceae, Ericaceae y Fabaceae. La diversidad de la dieta durante la estación húmeda y seca no presentó diferencias significativas (H’= 0.918 y H’=0.867 respectivamente. El porcentaje de similitud entre ambas temporadas fue de 58%. La diferencia entre la frecuencia de aparición de las especies vegetales fue mayor en la estación húmeda. Del total de especies consumidas, el mayor porcentaje estuvo constituido por las herbáceas. Las especies preferidas a lo largo del año fueron: Sedum dendroideum (herbácea y Satureja macrostema (arbusto. La riqueza de especies en la dieta fue menor a la observada en otras regiones con bosques tropicales y bosques mixtos, pero similar a la obtenida en un bosque tropical seco en Costa Rica y en los bosques de coníferas en Estados Unidos.Odocoileus virginianus diet (Artiodactyla: Cervidae in a temperate forest of Northern Oaxaca, Mexico. The Sierra Madre de Oaxaca region, located in the Northern state of Oaxaca, Mexico, is an area of forest ecosystems subject to high exploitation rates, although in some areas its temperate forests are conserved by indigenous community initiatives that live there. We analyzed the diet of white tailed-deer (Odocoileus virginianus in the localities of

INVENTARIO DE MAMÍFEROS EN UN BOSQUE DE LOS ANDES CENTRALES DE COLOMBIA

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SÁNCHEZ FRANCISCO

2004-06-01

Full Text Available Se usaron técnicas de captura, observación directa y registro indirecto para obtenerun inventario de mamíferos en un bosque andino de Colombia. Se realizaronmuestreos entre octubre de 1998 y abril de 1999 en la Reserva Río Blanco (Manizales,Departamento de Caldas, entre 2200 - 3750 m de altitud. Para capturar pequeñosmamíferos no voladores se usaron trampas Sherman. Para capturar murciélagos seusaron mallas de niebla y colectas manuales. Para registrar medianos y grandesmamíferos se usaron trampas Tomahawk, puntos de observación, recorridos, trampasde huellas, rastros y encuestas. Se registraron 42 especies de mamíferospertenecientes a doce órdenes. El inventario de pequeños mamíferos no voladoresy murciélagos es incompleto; se dan sugerencias para complementarlo. Las trampasde huellas, los rastros y las encuestas fueron técnicas más eficientes para registrarmedianos y grandes mamíferos, que la captura con trampas Tomahawk, los recorridosy los puntos de observación. Se hacen observaciones y se dan recomendacionespara implementar las diferentes técnicas en bosques andinos.

Evaluating process origins of sand-dominated fluvial stratigraphy

Science.gov (United States)

Chamberlin, E.; Hajek, E. A.

2015-12-01

Sand-dominated fluvial stratigraphy is often interpreted as indicating times of relatively slow subsidence because of the assumption that fine sediment (silt and clay) is reworked or bypassed during periods of low accommodation. However, sand-dominated successions may instead represent proximal, coarse-grained reaches of paleo-river basins and/or fluvial systems with a sandy sediment supply. Differentiating between these cases is critical for accurately interpreting mass-extraction profiles, basin-subsidence rates, and paleo-river avulsion and migration behavior from ancient fluvial deposits. We explore the degree to which sand-rich accumulations reflect supply-driven progradation or accommodation-limited reworking, by re-evaluating the Castlegate Sandstone (Utah, USA) and the upper Williams Fork Formation (Colorado, USA) - two Upper Cretaceous sandy fluvial deposits previously interpreted as having formed during periods of relatively low accommodation. Both units comprise amalgamated channel and bar deposits with minor intra-channel and overbank mudstones. To constrain relative reworking, we quantify the preservation of bar deposits in each unit using detailed facies and channel-deposit mapping, and compare bar-deposit preservation to expected preservation statistics generated with object-based models spanning a range of boundary conditions. To estimate the grain-size distribution of paleo-sediment input, we leverage results of experimental work that shows both bed-material deposits and accumulations on the downstream side of bars ("interbar fines") sample suspended and wash loads of active flows. We measure grain-size distributions of bar deposits and interbar fines to reconstruct the relative sandiness of paleo-sediment supplies for both systems. By using these novel approaches to test whether sand-rich fluvial deposits reflect river systems with accommodation-limited reworking and/or particularly sand-rich sediment loads, we can gain insight into large

Unsteady Landscapes: Climatic and Tectonic Controls on Fluvial Terrace Formation

Science.gov (United States)

Clubb, F. J.; Mudd, S. M.

2017-12-01

Fluvial terraces are common landforms throughout mountainous regions which represent abandoned remnants of active river systems and their floodplains. The formation of these landforms points to a fundamental unsteadiness in the incision rate of the fluvial network, providing important information on channel response to climatic, tectonic, and base-level forcing, sediment storage and dynamics within mountainous systems, and the relative importance of lateral and vertical incision rates. In his 1877 Report on the Geology of the Henry Mountains, G.K. Gilbert suggested that strath terraces may form due to climatically-driven increase in sediment supply, causing armouring of the channel bed and hindering vertical incision. An alternative hypothesis suggests that strath terraces may be preserved through progressive tectonic uplift or base-level fall. These different formation mechanisms should result in varying distribution of terrace elevations along channels: if terraces are formed through climate-driven variations in sediment supply, we might expect that terrace elevations would be random, whereas progressive fluvial incision should result in a series of terraces with a systematic elevation pattern. Here we test alternative hypotheses for strath terrace formation using a new method for objectively and rapidly identifying terrace surfaces from digital elevation models (DEMs) over large spatial scales. Our new method identifies fluvial terraces using their gradient and elevation compared to the modern channel, thresholds of which are statistically calculated from the DEM and do not need to be set manually by the user. We use this method to extract fluvial terraces for every major river along the coast of California, and quantify their distribution and elevation along the fluvial long profile. Our results show that there is no systematic pattern in terrace elevations despite a well-constrained spatial variation in uplift rates, suggesting that terraces in this region do

A natureza e o lugar habitado como âmbitos da experiência estética: novos entendimentos da relação ser humano - ambiente Nature and space as scopes for aesthetic experience: new understanding of the relationship human being - environment

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Andréia Aparecida Marin

2009-08-01

Full Text Available A percepção que o ser humano tem da natureza e do espaço habitado é marcada pela imaginação, pela afetividade, pela memória e pela sensibilidade estética. O significado da experiência estética está presente tanto nas construções do lugar habitado quanto na contemplação dos ambientes preservados. No presente ensaio, propomos um caminho reflexivo que evidencia essa necessidade estética do humano, focando-a nas categorias natureza e espaços do cotidiano como âmbitos de vivência. Tecemos considerações sobre os possíveis significados da teoria estética para a educação ambiental. Para tanto, partimos do resgate de referenciais teóricos da fenomenologia e do campo da filosofia estética, que incluem Merleau-Ponty, Bachelard, Dufrenne e Quintás.Human being's perception of nature and of the inhabited space is marked by imagination, affectivity, memory and aesthetic sensibility. The meaning of aesthetic experience is present in the buildings of the inhabited place as well as in the sight of preserved environments. In the present paper we propose a reflective way that makes evident this aesthetic need of mankind, focusing it in the categories of natural and daily spaces as scopes of life experience. We consider the possible meanings of aesthetic theory for environmental education. Thus we start at the recovery of theoretical references of phenomenology and of aesthetic philosophy that include Merleau-Ponty, Bachelard, Dufrenne, and Quintás.

Fluvial deposits as an archive of early human activity: Progress during the 20 years of the Fluvial Archives Group

Science.gov (United States)

Chauhan, Parth R.; Bridgland, David R.; Moncel, Marie-Hélène; Antoine, Pierre; Bahain, Jean-Jacques; Briant, Rebecca; Cunha, Pedro P.; Despriée, Jackie; Limondin-Lozouet, Nicole; Locht, Jean-Luc; Martins, Antonio A.; Schreve, Danielle C.; Shaw, Andrew D.; Voinchet, Pierre; Westaway, Rob; White, Mark J.; White, Tom S.

2017-06-01

Fluvial sedimentary archives are important repositories for Lower and Middle Palaeolithic artefacts throughout the 'Old World', especially in Europe, where the beginning of their study coincided with the realisation that early humans were of great antiquity. Now that many river terrace sequences can be reliably dated and correlated with the globally valid marine isotope record, potentially useful patterns can be recognized in the distribution of the find-spots of the artefacts that constitute the large collections that were assembled during the years of manual gravel extraction. This paper reviews the advances during the past two decades in knowledge of hominin occupation based on artefact occurrences in fluvial contexts, in Europe, Asia and Africa. As such it is an update of a comparable review in 2007, at the end of IGCP Project no. 449, which had instigated the compilation of fluvial records from around the world during 2000-2004, under the auspices of the Fluvial Archives Group. An overarching finding is the confirmation of the well-established view that in Europe there is a demarcation between handaxe making in the west and flake-core industries in the east, although on a wider scale that pattern is undermined by the increased numbers of Lower Palaeolithic bifaces now recognized in East Asia. It is also apparent that, although it seems to have appeared at different places and at different times in the later Lower Palaeolithic, the arrival of Levallois technology as a global phenomenon was similarly timed across the area occupied by Middle Pleistocene hominins, at around 0.3 Ma.

Notas sobre la conducta de crianza del Carpintero Bataraz Grande (Picoides lignarius) en el bosque lluvioso templado del sur de Chile

OpenAIRE

Figueroa Rojas, Ricardo A.; Corales Stappung, E. Soraya

2003-01-01

En el verano de 1995, durante tres días estudiamos la conducta de crianza de una pareja de Carpintero Bataraz Grande (Picoides lignarius) en el bosque lluvioso templado del sur de Chile. La pareja observada anidó en el interior de un tocón muerto de arrayán (Luma apiculata), en una franja de bosque ripario. La hembra hizo una mayor contribución a la alimentación de los pichones (78% del total de aportes de presa) en comparación con el macho (22%). Esta tendencia fue constante durante los tres...

Martian Fluvial Conglomerates at Gale Crater

Science.gov (United States)

Williams, R. M. E.; Grotzinger, J. P.; Dietrich, W. E.; Gupta, S.; Sumner, D. Y.; Wiens, R. C.; Mangold, N.; Malin, M. C.; Edgett, K. S.; Maurice, S.; Forni, O.; Gasnault, O.; Ollila, A.; Newsom, H. E.; Dromart, G.; Palucis, M. C.; Yingst, R. A.; Anderson, R. B.; Herkenhoff, K. E.; Le Mouélic, S.; Goetz, W.; Madsen, M. B.; Koefoed, A.; Jensen, J. K.; Bridges, J. C.; Schwenzer, S. P.; Lewis, K. W.; Stack, K. M.; Rubin, D.; Kah, L. C.; Bell, J. F.; Farmer, J. D.; Sullivan, R.; Van Beek, T.; Blaney, D. L.; Pariser, O.; Deen, R. G.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Edgar, Lauren; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Blank, Jennifer; Weigle, Gerald; Schmidt, Mariek; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Ehlmann, Bethany; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Rice, Melissa; Siebach, Kirsten; Stolper, Edward; Brunet, Claude; Hipkin, Victoria; Léveillé, Richard; Marchand, Geneviève; Sobrón Sánchez, Pablo; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Aparicio, Carlos Armiens; Caride Rodríguez, Javier; Carrasco Blázquez, Isaías; Gómez Gómez, Felipe; Elvira, Javier Gómez; Hettrich, Sebastian; Lepinette Malvitte, Alain; Marín Jiménez, Mercedes; Frías, Jesús Martínez; Soler, Javier Martín; Torres, F. Javier Martín; Molina Jurado, Antonio; Sotomayor, Luis Mora; Muñoz Caro, Guillermo; Navarro López, Sara; González, Verónica Peinado; García, Jorge Pla; Rodriguez Manfredi, José Antonio; Planelló, Julio José Romeral; Alejandra Sans Fuentes, Sara; Sebastian Martinez, Eduardo; Torres Redondo, Josefina; O'Callaghan, Roser Urqui; Zorzano Mier, María-Paz; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Cécile; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; Uston, Claude d.; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Szopa, Cyril; Robert, François; Sautter, Violaine; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; Clegg, Sam; Cousin, Agnès; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Treiman, Allan; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Dyar, M. Darby; Fassett, Caleb; Blake, David F.; Bristow, Thomas; DesMarais, David; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Bleacher, Lora; Brinckerhoff, William; Choi, David; Conrad, Pamela; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Brinza, David; Calef, Fred; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Hurowitz, Joel; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; de la Torre Juarez, Manuel; Vasavada, Ashwin R.; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Ming, Douglas; Morris, Richard V.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Vaniman, David; Leshin, Laurie; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Grant, John; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Clark, Benton; Wolff, Michael; McLennan, Scott; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Blanco Ávalos, Juan José; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; González, Rafael Navarro; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Kortmann, Onno; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Jakosky, Bruce; Zunic, Tonci Balic; Frydenvang, Jens; Kinch, Kjartan; Stipp, Susan Louise Svane; Boyd, Nick; Campbell, John L.; Gellert, Ralf; Perrett, Glynis; Pradler, Irina; VanBommel, Scott; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mellin, Reinhold Mueller; Schweingruber, Robert Wimmer; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Gordon, Suzanne; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

2013-05-01

Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

Estructura, diversidad y dinámica de la vegetación en el ecotono bosque-páramo: revisión de la evidencia en la Cordillera de Mérida

OpenAIRE

Luis Daniel Llambí

2015-01-01

En los Andes tropicales, el límite altitudinal de los bosques corresponde a una compleja zona de transición entre el bosque paramero y el páramo andino. En el límite inferior de esta zona ocurre a su vez una transición gradual entre el bosque y las selvas nubladas. La ordenación del territorio en estos ecosistemas se ha convertido en un tema prioritario en virtud de la creciente amenaza que representan para su conservación las actividades agropecuarias y la minería. En este trabajo se revisar...

Respuestas foliares de Aristotelia chilensis (Molina Stuntz (Elaeocarpaceae a la fragmentación del bosque maulino Leaf responses of Aristotelia chilensis (Molina Stuntz (Elaeocarpaceae to the fragmentation of the Maulino forest

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FIORELLA REPETTO-GIAVELLI

2007-12-01

Full Text Available La fragmentación que ha sufrido el bosque nativo de Chile debido a la fuerte presión antrópica ha causado, además de la grave pérdida de habitat, la modificación del microclima de los parches de bosque remanente que alguna vez constituyeron un bosque continuo de especies nativas. Estos cambios generarían respuestas morfológicas, químicas y fisiológicas en plantas capaces de adaptarse a las nuevas condiciones. Este estudio tiene como objetivo identificar respuestas a nivel de las hojas ante el aumento de radiación solar y disminución de agua en el suelo que ocurre al interior de los fragmentos. Para esto utilizamos a Aristotelia chilensis, especie que crece tanto en fragmentos como en bosque continuo, y comparamos parámetros relacionados a su morfología foliar en bosque y fragmentos y medimos su repercusión en la capacidad fotosintética de A. chilensis. En términos morfológicos, se observó una disminución del área foliar y del área foliar específica en los fragmentos, siendo 1,2 veces menor que en el bosque continuo. En los fragmentos, el grosor de la epidermis y del parénquima esponjoso son más de 1,3 veces mas gruesos que en el bosque continuo. El grosor del parénquima en empalizada, en cambio, no se vio modificado. La cantidad de nitrógeno en las hojas es 1,2 veces mayor en el bosque continuo que en los fragmentos, mientras que el contenido de carbono no varía. La conductancia estomática en el bosque continuo fue 1,5 veces mayor que en los fragmentos. Aristotelia chilensis responde morfológica y fisiológicamente ante los cambios abióticos generados por la fragmentación de los bosques, lo que le permite sobrevivir tanto en ambientes de baja luminosidad como el bosque continuo y en ambientes de alta luminosidad y bajo contenido hídrico como los fragmentos de bosque, manteniendo tasas fotosintéticas semejantes en ambos ambientesFragmentation of the Maulino forest implies significant habitat loss, as well as the

Utilization of alternatives fuels in a fluvial convoy; Utilizacao de combustiveis alternativos em um comboio fluvial

Energy Technology Data Exchange (ETDEWEB)

Padovezi, Carlos D; Giraldo, Arnaldo

1987-12-31

This work presents the results of tests performed with ethanol and methanol in a fluvial convoy in Tiete river, Sao Paulo State - Southeast Brazil. It also outlines a comparison and evaluation methodology. 9 figs., 3 tabs.

Utilization of alternatives fuels in a fluvial convoy; Utilizacao de combustiveis alternativos em um comboio fluvial

Energy Technology Data Exchange (ETDEWEB)

Padovezi, Carlos D.; Giraldo, Arnaldo

1986-12-31

This work presents the results of tests performed with ethanol and methanol in a fluvial convoy in Tiete river, Sao Paulo State - Southeast Brazil. It also outlines a comparison and evaluation methodology. 9 figs., 3 tabs.

Landform Evolution Modeling of Specific Fluvially Eroded Physiographic Units on Titan

Science.gov (United States)

Moore, J. M.; Howard, A. D.; Schenk, P. M.

2015-01-01

Several recent studies have proposed certain terrain types (i.e., physiographic units) on Titan thought to be formed by fluvial processes acting on local uplands of bedrock or in some cases sediment. We have earlier used our landform evolution models to make general comparisons between Titan and other ice world landscapes (principally those of the Galilean satellites) that we have modeled the action of fluvial processes. Here we give examples of specific landscapes that, subsequent to modeled fluvial work acting on the surfaces, produce landscapes which resemble mapped terrain types on Titan.

Riparian shrub metal concentrations and growth in amended fluvial mine tailings

Science.gov (United States)

Fluvial mine tailing deposition has caused extensive riparian damage throughout the western United States. Willows are often used for fluvial mine tailing revegetation, but some species accumulate excessive metal concentrations which could be detrimental to browsers. In a greenhouse experiment, gr...

Morphology of fluvial levee series along a river under human influence, Maros River, Hungary

Science.gov (United States)

Kiss, Tímea; Balogh, Márton; Fiala, Károly; Sipos, György

2018-02-01

The development and morphometry of fluvial levees reflect the connection between channel and overbank processes, which can be altered by various human activities. The aims of this study are to investigate the morphology and spatial characteristics of fluvial levees and evaluate the role of some local- and catchment-scale human activities on their medium-term (150 years) development. This study applies LiDAR data along a 53-km-long reach of the Maros River in Hungary. Six fluvial levee types are identified based on the beginning and end of their evolution. These levee types were generated by local nineteenth century channel regulation works (cutoffs) and mid-twentieth century channel narrowing, which was caused by gravel mining and water impoundment in the upstream sections. However, other human activities also influenced the development of active fluvial levees because their horizontal evolution could have been limited by embanked flood-protection levees or the widening of low-lying floodplain benches that were generated by channel narrowing. Additionally, revetment constructions influenced their vertical parameters as higher fluvial levees developed along the fixed banks. Generally, the older active fluvial levees are wider, while the younger active levees are narrower with steeper slopes but not always lower. On the low-lying floodplain levels (benches), the youngest fluvial levees evolved quite rapidly and consist of coarser material. Currently, only 9.8- to 38-year return-period floods could cover the fluvial levees, contributing to their evolution. This fact and the development of fluvial levee series with two-three members reflect a gradual decoupling of the channel from the floodplain.

Heavy mineral analyses as a powerful tool in fluvial geomorphology

Science.gov (United States)

von Suchodoletz, Hans; Gärtner, Andreas; Faust, Dominik

2014-05-01

The Marneuli depression is a tectonic sub-basin of the Transcaucasian depression in eastern Georgia, filled with several decametres of fluvial, lacustrine and aeolian Quaternary sediments. In order to reconstruct past landscape evolution of the region we studied Late Quaternary fluvial sediments found along several rivers that flow through that depression. Whereas Holocene river sediments could generally easily be assigned to corresponding rivers, this was not always the case for older fluvial sediments. For this reason, we studied the heavy mineral contents of five recent rivers and of four sedimentary deposits of potential precursors. A total of 4088 analysed heavy mineral grains enabled us to set up the characteristic heavy mineral distribution pattern for each sample. Using these data, we were able to reconstruct the most likely source areas of the Late Pleistocene fluvial sediments and to link them with the catchment areas of recent rivers. This allowed us to identify and to substantiate significant Late Quaternary river diversions that could at least partly be assigned to ongoing tectonic processes.

Los bosques de Abies guatemalensis Rehder de San Marcos, Guatemala: una oportunidad para su restauración ecológica

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José Vicente Martínez Arévalo

2016-08-01

Full Text Available El pinabete, Abies guatemalensis Rehder, es una especie distribuida en las montañas altas de Guatemala. Según el Consejo Nacional de Áreas Protegidas (Conap, sus poblaciones se encuentran severamente fragmentadas. Por su rareza y fragmentación, esta especie se encuentra protegida por el Convenio sobre el Comercio Internacional de Especies Amenazadas de Fauna y Flora Silvestre (Cites, lo que pone en relieve la importancia de la recuperación de sus bosques para su debida conservación. El éxito de su establecimiento puede mejorase al sembrarla junto a plantas nodriza, que le ayudarían a sobrevivir a las condiciones secas del año y las heladas que se presentan en las zonas de mayor altitud del país durante los meses de noviembre a febrero. Este trabajo muestra las características físicas, químicas y de vegetación del área de tres bosques de pinabete (A. guatemalensis de la parte alta de San Marcos. Además, presenta la propuesta de restauración ecológica estimulada simulando la sucesión vegetal del área. Se elaboraron mapas, y describieron tres bosques de pinabete y sus alrededores; se presenta el estudio de la composición química del suelo y la vegetación y su representación en diferentes etapas de sucesión vegetal. Además, se propone la recuperación de áreas alrededor de parches de bosque, consistente en establecer plantas arbustivas en lugares abiertos donde aún no hay; por su parte en aquellas áreas donde ya se encuentren arbustos, se propone utilizarlos como plantas nodriza para establecer árboles de varias especies buscando mantener biodiversidad de especies arbóreas.

bajo el bosque en Costa Rica. 1980-2000

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Rafael Ocampo

2007-01-01

Full Text Available La ipecacuana o raicilla, hierba nativa de América, es la única planta medicinal del trópico húmedo de Costa Rica cultivada bajo el bosque. Es cultivada en la región Huetar Norte, limítrofe con Nicaragua; la raíz seca de ipecacuana se ha comercializado en Costa Rica como materia prima para la industria farmacéutica internacional desde principios del siglo XX. De acuerdo con las estadísticas oficiales, las exportaciones de raicilla desde Costa Rica en los últimos 20 años han significado un promedio de 64 t año-1. Este trabajo resume actividades relacionadas con la descripción y cultivo de la planta, así como algunos de los aspectos agroecológicos de su cultivo.

Oribátidos arborícolas del «Paseo del Bosque» (La Plata, provincia de Buenos Aires, Argentina Canopy soil suspendend oribatids from the «Paseo del Bosque» (La Plata, province of Buenos Aires, Argentina

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Ana Salazar Martínez

2007-07-01

Full Text Available En esta nota se aporta información sobre los oribátidos arborícolas del Paseo del Bosque, La Plata, Argentina (34º 54' S, 57º 55' W, a partir de muestreos realizados en suelos suspendidos con distinta concentración de detritos. La fauna de oribátidos estuvo representada por 17 especies, siendo Cultroribula sp., Pheroliodes cf. minutus Baranek, Rhysotritia peruensis Hammer y Oppiella nova Oudemans las de mayor importancia relativa. De las especies registradas, 76 % son propias del ambiente arborícola.This work deals with the arboreal oribatids of «Paseo del Bosque», La Plata, Argentina (34º 54' S, 57º 55' W. Samples were taken from suspended soils exhibiting unequal detritus concentrations. The overall sample included 17 oribatid species, exhibiting Cultroribula sp., Pheroliodes cf. minutus Baranek, Rhysotritia peruensis Hammer and Oppiella nova Oudemans the highest relative importance. Seventy percent of the recorded species are representative of the arboricole environment.

RELACIÓN ENTRE LA DIVERSIDAD DE ANUROS Y LOS ESTADOS SUCESIONALES DE UN BOSQUE MUY HÚMEDO MONTANO BAJO DEL VALLE DEL CAUCA, SUROCCIDENTE COLOMBIANO

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GARCÍA-R. JUAN CARLOS

2007-12-01

Full Text Available Se examinó la relación de parámetros vegetales y variables climáticas con ladistribución y la abundancia de anuros en un bosque muy húmedo montano bajo deloccidente del Valle del Cauca, Colombia. Se muestrearon durante siete meses seistransectos en tres tipos de hábitat (bosque secundario, bosque secundario tempranoy matorral. Se obtuvieron datos de las características del bosque (cobertura, alturaspromedias y densidades de diferentes estratos, profundidad de la hojarasca, temperaturadel aire, temperatura del suelo y humedad relativa en cada sitio. Se registraron cincoespecies del género Pristimantis y una del género “Eleutherodactylus”, siendo la másabundante P. brevifrons con un total de 19 individuos, seguida de P. palmeri con 15 y P.erythropleura con 14. La distribución de las especies presentó diferencias significativasentre los hábitats y las variables climáticas. La abundancia de las especies en el bosquesecundario estuvo correlacionada con la temperatura del suelo, y en bosque secundariotemprano y matorral con la humedad relativa. De acuerdo con los aspectos estructuralesde la vegetación, se sugiere la existencia de tres comportamientos diferentes dentrodel grupo de anuros respecto a los siguientes parámetros: cobertura vegetal (%, alturapromedio (m del estrato subarbóreo (Ar, densidad de este estrato (ind/m2, densidad(ind/m2 del estrato arbustivo (ar y la profundidad de la capa de hojarasca (cm. Porlo tanto, se observan tres grupos de especies aparentemente diferentes, definidossegún los siguientes criterios: el grupo I, constituido por especies que toleran más losambientes medianamente intervenidos (P. brevifrons, P. erythropleura, “E”. mantipus;el grupo II, cuyas especies se encuentran presentes en ambientes más conservados(P. calcaratus, P. thectopternus; y el grupo III conformado por P. palmeri, presenteen ambientes mediana y altamente intervenidos

Fluvial response to the last Holocene rapid climate change in the Northwestern Mediterranean coastlands

Science.gov (United States)

Degeai, Jean-Philippe; Devillers, Benoît; Blanchemanche, Philippe; Dezileau, Laurent; Oueslati, Hamza; Tillier, Margaux; Bohbot, Hervé

2017-05-01

The variability of fluvial activity in the Northwestern Mediterranean coastal lowlands and its relationship with modes of climate change were analysed from the late 9th to the 18th centuries CE. Geochemical analyses were undertaken from a lagoonal sequence and surrounding sediments in order to track the fluvial inputs into the lagoon. An index based on the K/S and Rb/S ratios was used to evidence the main periods of fluvial activity. This index reveals that the Medieval Climate Anomaly (MCA) was a drier period characterized by a lower fluvial activity, while the Little Ice Age (LIA) was a wetter period with an increase of the river dynamics. Three periods of higher than average fluvial activity were evidenced at the end of the first millennium CE (ca. 900-950 cal yr CE), in the first half of the second millennium CE (ca. 1150-1550 cal yr CE), and during the 1600s-1700s CE (ca. 1650-1800 cal yr CE). The comparison of these fluvial periods with other records of riverine or lacustrine floods in Spain, Italy, and South of France seems to indicate a general increase in fluvial and flood patterns in the Northwestern Mediterranean in response to the climate change from the MCA to the LIA, although some episodes of flooding are not found in all records. Besides, the phases of higher than average fluvial dynamics are in good agreement with the North Atlantic cold events evidenced from records of ice-rafted debris. The evolution of fluvial activity in the Northwestern Mediterranean coastlands during the last millennium could have been driven by atmospheric and oceanic circulation patterns.

Geomorphic Unit Tool (GUT): Applications of Fluvial Mapping

Science.gov (United States)

Kramer, N.; Bangen, S. G.; Wheaton, J. M.; Bouwes, N.; Wall, E.; Saunders, C.; Bennett, S.; Fortney, S.

2017-12-01

Geomorphic units are the building blocks of rivers and represent distinct habitat patches for many fluvial organisms. We present the Geomorphic Unit Toolkit (GUT), a flexible GIS geomorphic unit mapping tool, to generate maps of fluvial landforms from topography. GUT applies attributes to landforms based on flow stage (Tier 1), topographic signatures (Tier 2), geomorphic characteristics (Tier 3) and patch characteristics (Tier 4) to derive attributed maps at the level of detail required by analysts. We hypothesize that if more rigorous and consistent geomorphic mapping is conducted, better correlations between physical habitat units and ecohydraulic model results will be obtained compared to past work. Using output from GUT for coarse bed tributary streams in the Columbia River Basin, we explore relationships between salmonid habitat and geomorphic spatial metrics. We also highlight case studies of how GUT can be used to showcase geomorphic impact from large wood restoration efforts. Provided high resolution topography exists, this tool can be used to quickly assess changes in fluvial geomorphology in watersheds impacted by human activities.

Modeling plan-form deltaic response to changes in fluvial sediment supply

NARCIS (Netherlands)

Nienhuis, J.H.; Ashton, A.D.; Roos, Pieter C.; Hulscher, Suzanne J.M.H.; Giosan, L.; Kranenburg, W.M.; Horstman, E.M.; Wijnberg, K.M.

2012-01-01

This study focuses on the effects of changes in fluvial sediment supply on the plan-form shape of wave-dominated deltas. We apply a one-line numerical shoreline model to calculate shoreline evolution after (I) elimination and (II) time-periodic variation of fluvial input. Model results suggest four

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

Science.gov (United States)

Edgar, Lauren; Gupta, Sanjeev; Rubin, David M.; Lewis, Kevin W.; Kocurek, Gary A.; Anderson, Ryan; Bell, James F.; Dromart, Gilles; Edgett, Kenneth S.; Grotzinger, John P.; Hardgrove, Craig; Kah, Linda C.; LeVeille, Richard A.; Malin, Michael C.; Mangold, Nicholas; Milliken, Ralph E.; Minitti, Michelle; Palucis, Marisa C.; Rice, Melissa; Rowland, Scott K.; Schieber, Juergen; Stack, Kathryn M.; Sumner, Dawn Y.; Wiens, Roger C.; Williams, Rebecca M.E.; Williams, Amy J.

2018-01-01

This paper characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time, and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture, and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification to determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution, and bedform migration direction, this study concludes that the Shaler outcrop likely records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the northeast, across the surface of a bar that migrated southeast. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggests that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry, and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.

OBSERVACIONES SOBRE LA ESTRATIFICACIÓN VERTICAL DE ABEJAS EUGLOSINAS (APIDAE: EUGLOSSINI EN UN BOSQUE RIPARIO DE LA ORINOQUÍA COLOMBIANA

Directory of Open Access Journals (Sweden)

VÉLEZ DANNY

2005-12-01

Full Text Available Se realizaron observaciones sobre la distribución vertical de abejas euglosinas en un bosque ripario asociado al sistema de lagunas Mata-Mata (Meta-Colombia. Los estratos evaluados fueron: sotobosque (1.8 m, la parte media entre el dosel y sotobosque (12-16 m y el dosel (18-25 m. Un total de 33 machos pertenecientes a cinco especies de Eulaema y Euglossa fueron capturados usando Cineol en trampas de caída. Eulaema nigrita y Euglossa intersecta fueron las especies más abundantes y se capturaron en todos los estratos. En general, no se encontró ninguna diferencia significativa en la diversidad, la abundancia y la riqueza de abejas en los diferentes estratos del bosque.

Notas sobre la conducta de crianza del Carpintero Bataraz Grande (Picoides lignarius) en el bosque lluvioso templado del sur de Chile

OpenAIRE

Figueroa Rojas, Ricardo A.; Corales Stappung, E. Soraya

2003-01-01

En el verano de 1995, durante tres días estudiamos la conducta de crianza de una pareja de Carpintero Bataraz Grande (Picoides lignarius) en el bosque lluvioso templado del sur de Chile. La pareja observada anidó en el interior de un tocón muerto de arrayán (Luma apiculata), en una franja de bosque ripario. La hembra hizo una mayor contribución a la alimentación de los pichones (78% del total de aportes de presa) en comparación con el macho (22%). Esta tendencia fue constante durante los tres...

Productos del mercado artesanal en la ciudad de Leticia (Amazonia colombiana elaborados con especies de bosques de Mauritia flexuosa L.f.

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Sandra Lorena Franco Arango

2015-06-01

Full Text Available Los productos forestales no maderables (PFNMs han tomado fuerza como alternativa para la conservación de ecosistemas y la generación de ingresos económicos en las poblaciones asociadas. Se presenta un mayor interés sobre los productos que provienen de bosques oligárquicos (poco diversos y con alta densidad relativa, especialmente los dominados por palmas, como por ejemplo los bosques de Mauritia flexuosa (aguajales, cananguchales o buritizales. En el mercado artesanal de Leticia (Amazonia colombiana se identificaron 68 productos provenientes de nueve especies de plantas del canaguchal, teniendo las palmas (Astrocaryum chambira, Euterpe precatoria, M. flexuosa, Oenocarpus bataua y Socratea exorrhiza el mayor potencial comercial. Los productos más frecuentes fueron las mochilas de fibras de A. chambira (chambira y los precios de venta más altos correspondieron a las esculturas de Brosimum rubescens (palo de sangre. No existen estadísticas oficiales de este mercado, ni entes del Estado que regulen y orienten la producción y comercialización de los productos que se extraen del bosque. No obstante, los PFNMs representan una alternativa para diversificar las oportunidades productivas de los pobladores de la región.

Contemporary Conceptual Approaches in Fluvial Geomorphology

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Mônica dos Santos Marçal

2016-06-01

Full Text Available Contemporary fluvial geomorphology faces challenging questions, especially as it goes by understanding the Late Holocene/Anthropocene period, which has repercussions today and are intrinsically important to understand the human river disturbance. Given the scale that physical rates operate in complex river systems, two conceptual paths were developed to analyze the spatial and temporal organization. The network view emphasizes controls on catchment-scale and a reach approach focuses on discontinuity and local controls. Fluvial geomorphology has seek to understand the organization of complex river systems from the integrated view of the continuity and discontinuity paradigm. This integrated approach has stimulated within the geomorphology, the emergence of new theoretical-methodological instruments. It is recognized that rivers management is an ongoing process, part of the socio-cultural development, which refers to both a social movement and scientific exercise.

Protracted fluvial recovery from medieval earthquakes, Pokhara, Nepal

Science.gov (United States)

Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Andermann, Christoff; Schönfeldt, Elisabeth; Seidemann, Jan; Adhikari, Basanta R.; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

2016-04-01

River response to strong earthquake shaking in mountainous terrain often entails the flushing of sediments delivered by widespread co-seismic landsliding. Detailed mass-balance studies following major earthquakes in China, Taiwan, and New Zealand suggest fluvial recovery times ranging from several years to decades. We report a detailed chronology of earthquake-induced valley fills in the Pokhara region of western-central Nepal, and demonstrate that rivers continue to adjust to several large medieval earthquakes to the present day, thus challenging the notion of transient fluvial response to seismic disturbance. The Pokhara valley features one of the largest and most extensively dated sedimentary records of earthquake-triggered sedimentation in the Himalayas, and independently augments paleo-seismological archives obtained mainly from fault trenches and historic documents. New radiocarbon dates from the catastrophically deposited Pokhara Formation document multiple phases of extremely high geomorphic activity between ˜700 and ˜1700 AD, preserved in thick sequences of alternating fluvial conglomerates, massive mud and silt beds, and cohesive debris-flow deposits. These dated fan-marginal slackwater sediments indicate pronounced sediment pulses in the wake of at least three large medieval earthquakes in ˜1100, 1255, and 1344 AD. We combine these dates with digital elevation models, geological maps, differential GPS data, and sediment logs to estimate the extent of these three pulses that are characterized by sedimentation rates of ˜200 mm yr-1 and peak rates as high as 1,000 mm yr-1. Some 5.5 to 9 km3 of material infilled the pre-existing topography, and is now prone to ongoing fluvial dissection along major canyons. Contemporary river incision into the Pokhara Formation is rapid (120-170 mm yr-1), triggering widespread bank erosion, channel changes, and very high sediment yields of the order of 103 to 105 t km-2 yr-1, that by far outweigh bedrock denudation rates

Invertebrados acuáticos asociados a la Bromelia Tillandsia turneri Baker. en un bosque altoandino

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María Fabiola Ospina

2000-07-01

Full Text Available Las bromelias como plantas fitotelmas mantienen una compleja cadena trófica que incluye invertebrados asociados a depósitos de agua. Se determinó la comunidad de invertebrados acuáticos de la bromelia Tillandsia turneri en un bosque altoandino en el Municipio de Chocontá, Cundinamarca, Colombia. Se estudiaron 37 individuos de la bromelia ubicadas desde 0 hasta 6 m de altura, a las cuales se realizaron mediciones morfológicas, de contenido de agua y análisis fisicoquímico de esta y se colectaron los invertebrados asociados. Los órdenes mas abundantes fueron Coleóptera, Díptera y Cladócera; por medio de un análisis de similaridad de Morisita Horn se encontró que las bromelias son similares en cuanto a composición de invertebrados, por lo que se sugiere que pertenecen a un solo estrato dentro del bosque y que los procesos de ovoposición y dispersión para los grupos estudiados tienen igual probabilidad de ocurrir en las bromelias ubicadas de 0 a 6 m de altura.

Hormigas zompopas (Atta cephalotes influyen positivamente en la biodiversidad vegetal de bosques húmedos tropicales

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Javier Ruiz

2010-08-01

Full Text Available REALIZAMOS OBSERVACIONES DE LA HISTORIA NATURAL DE LA HORMIGA ZOMPOPA (Atta cephalotes en el período de 1995 a 2010. Monitoreamos una población de hormigas zompopas en 2003 y realizamos experimentos de campo en 2006 en el bosque húmedo tropical de la Estación Biológica La Unión en Nicaragua. Los nidos de hormiga zompopa fueron mapeados dentro de una parcela permanente de 6.5 hectáreas. Se estimó lacomposición de especies vegetales en el área del nido de la hormiga, y se realizó un conteo de plántulas dicotiledóneas y plántulas de palmas (monocotiledóneas. Los resultados indican que las hormigas zompopas prefieren defoliar plántulas de especies dicotiledóneas,favoreciendo la regeneración de palmas sobre el nido de las hormigas. Las zompopas favorecen la regeneración de palmas en áreas donde ellas establecen el montículo principal de sus nidos. En el artículo se discuten las implicaciones de estos resultados para la dinámicade la regeneración en bosques húmedos tropicales.

Abiotic alterations caused by forest fragmentation affect tree regeneration: a shade and drought tolerance gradient in the remnants of Coastal Maulino Forest Alteraciones abióticas causadas por la fragmentación del bosque afectan la regeneración arbórea: un gradiente de tolerancia a la sombra y la sequía en los remanentes del Bosque Maulino Costero

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PABLO C GUERRERO

2009-01-01

by regeneration niche attributes for implementing conservation actions and ecological restoration.La regeneración en plantas está determinada por las diferencias de luz y humedad del suelo entre hábitats, ambas variables son modificadas por la fragmentación de bosques a gran escala. Varios estudios consideran esas alteraciones como parte del mecanismo involucrado en el cambio comunitario en bosques tropicales. Sin embargo, en bosques mediterráneos y deciduos esa tendencia podría ser más severa, debido a que las plantas presentan un "trade off" entre la tolerancia a la sombra y a la sequía. Nuestro estudio fue realizado en el Bosque Maulino Costero: Reserva Nacional Los Queules (RNLQ y fragmentos aledaños de bosque. Hipotetizamos que Aristotelia chilensis (sombra intolerante pero tolerante a la sequía debería aumentar su regeneración en fragmentos pequeños de bosque, como consecuencia del cambio en la idoneidad del habitat (i.e. más luminoso y seco, mientras que, Cryptocarya alba (sombra tolerante pero sequía intolerante debería reducir su regeneración en fragmentos pequeños de bosque. Nosotros además esperamos que Nothofagus glauca y N. obliqua, ambas con tolerancias a la sombra y a la sequía intermedias entre A. chilensis y C. alba, deberían responder en menor medida a la fragmentación del bosque. En este estudio utilizamos dos evaluaciones: (i la abundancia de plántulas y juveniles a través de observaciones de campo y (ii la germinación y establecimiento de plántulas vía un experimento de campo. Los patrones de regeneración natural de C. alba indican una reducción en la regeneración dentro de los fragmentos pequeños de bosque comparado con la RNLQ, a pesar de que en el experimento de campo, la proporción de semillas germinadas, de plántulas establecidas y reclutadas no variaron entre hábitats. Por el contrario, la regeneración de A. chilensis y de N. glauca fueron favorecidas por la fragmentación del bosque, con un aumento en las

Modeling Long-Term Fluvial Incision : Shall we Care for the Details of Short-Term Fluvial Dynamics?

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Lague, D.; Davy, P.

2008-12-01

Fluvial incision laws used in numerical models of coupled climate, erosion and tectonics systems are mainly based on the family of stream power laws for which the rate of local erosion E is a power function of the topographic slope S and the local mean discharge Q : E = K Qm Sn. The exponents m and n are generally taken as (0.35, 0.7) or (0.5, 1), and K is chosen such that the predicted topographic elevation given the prevailing rates of precipitation and tectonics stay within realistic values. The resulting topographies are reasonably realistic, and the coupled system dynamics behaves somehow as expected : more precipitation induces increased erosion and localization of the deformation. Yet, if we now focus on smaller scale fluvial dynamics (the reach scale), recent advances have suggested that discharge variability, channel width dynamics or sediment flux effects may play a significant role in controlling incision rates. These are not factored in the simple stream power law model. In this work, we study how these short- term details propagate into long-term incision dynamics within the framework of surface/tectonics coupled numerical models. To upscale the short term dynamics to geological timescales, we use a numerical model of a trapezoidal river in which vertical and lateral incision processes are computed from fluid shear stress at a daily timescale, sediment transport and protection effects are factored in, as well as a variable discharge. We show that the stream power law model might still be a valid model but that as soon as realistic effects are included such as a threshold for sediment transport, variable discharge and dynamic width the resulting exponents m and n can be as high as 2 and 4. This high non-linearity has a profound consequence on the sensitivity of fluvial relief to incision rate. We also show that additional complexity does not systematically translates into more non-linear behaviour. For instance, considering only a dynamical width

Patrones de distribución de especies arbóreas de dosel y sotobosque a escala local en bosques de tierra firme, Amazonia colombiana

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Juan Sebastian Barreto-Silva

2014-03-01

Full Text Available El efecto de la variación ambiental en la estructura de las comunidades arbóreas en bosques tropicales, aún se debate. En paisajes como los bosques de tierra firme, donde el gradiente ambiental disminuye, el efecto de los suelos sobre los patrones de distribución de especies es mínimo. En contraste, un mayor efecto de la variación edáfica y topográfica sobre la composición florística, se ha reportado en estudios con diferentes tipos de plantas en bosques tropicales. Este estudio se realizó en diez hectáreas de una parcela permanente. Se evaluó el efecto de la variación ambiental y la configuración espacial sobre los patrones florísticos de las especies arbóreas a escala local, según el estado de desarrollo y categorías de abundancia relativa. Se registraron 14 074 individuos de 1 053 especies y 80 familias. Los suelos son ácidos, presentan altas concentraciones de Aluminio y son predominantemente arcillosos. La diversidad beta fue baja. Las diferencias florísticas explicadas fueron asociadas con procesos biológicos espacialmente estructurados, particularmente, con la limitación en dispersión. Aunque, la mayor parte de la variación no fue explicada por las variables consideradas. Estos resultados sugieren que procesos aleatorios son determinantes esenciales de la variación florística en bosques de tierra firme de la amazonia.

Experimental investigation of fluvial dike breaching due to flow overtopping

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El Kadi Abderrezzak, K.; Rifai, I.; Erpicum, S.; Archambeau, P.; Violeau, D.; Pirotton, M.; Dewals, B.

2017-12-01

The failure of fluvial dikes (levees) often leads to devastating floods that cause loss of life and damages to public infrastructure. Overtopping flows have been recognized as one of the most frequent cause of dike erosion and breaching. Fluvial dike breaching is different from frontal dike (embankments) breaching, because of specific geometry and boundary conditions. The current knowledge on the physical processes underpinning fluvial dike failure due to overtopping remains limited. In addition, there is a lack of a continuous monitoring of the 3D breach formation, limiting the analysis of the key mechanisms governing the breach development and the validation of conceptual or physically-based models. Laboratory tests on breach growth in homogeneous, non-cohesive sandy fluvial dikes due to flow overtopping have been performed. Two experimental setups have been constructed, permitting the investigation of various hydraulic and geometric parameters. Each experimental setup includes a main channel, separated from a floodplain by a dike. A rectangular initial notch is cut in the crest to initiate dike breaching. The breach development is monitored continuously using a specific developed laser profilometry technique. The observations have shown that the breach develops in two stages: first the breach deepens and widens with the breach centerline being gradually shifted toward the downstream side of the main channel. This behavior underlines the influence of the flow momentum component parallel to the dike crest. Second, the dike geometry upstream of the breach stops evolving and the breach widening continues only toward the downstream side of the main channel. The breach evolution has been found strongly affected by the flow conditions (i.e. inflow discharge in the main channel, downstream boundary condition) and floodplain confinement. The findings of this work shed light on key mechanisms of fluvial dike breaching, which differ substantially from those of dam

Characterizing fluvial heavy metal pollutions under different rainfall conditions: Implication for aquatic environment protection.

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Zhang, Lixun; Zhao, Bo; Xu, Gang; Guan, Yuntao

2018-09-01

Globally, fluvial heavy metal (HM) pollution has recently become an increasingly severe problem. However, few studies have investigated the variational characteristics of fluvial HMs after rain over long periods (≥1 year). The Dakan River in Xili Reservoir watershed (China) was selected as a case study to investigate pollution levels, influencing factors, and sources of HMs under different rainfall conditions during 2015 and 2016. Fluvial HMs showed evident spatiotemporal variations attributable to the coupled effects of pollution generation and rainfall diffusion. Fluvial HM concentrations were significantly associated with rainfall characteristics (e.g., rainfall intensity, rainfall amount, and antecedent dry period) and river flow, which influenced the generation and the transmission of fluvial HMs in various ways. Moreover, this interrelationship depended considerably on the HM type and particle size distribution. Mn, Pb, Cr, and Ni were major contributors to high values of the comprehensive pollution index; therefore, they should be afforded special attention. Additionally, quantitative source apportionment of fluvial HMs was conducted by combining principal component analysis with multiple linear regression and chemical mass balance models to obtain comprehensive source profiles. Finally, an environment-friendly control strategy coupling "source elimination" and "transport barriers" was proposed for aquatic environment protection. Copyright © 2018 Elsevier B.V. All rights reserved.

Signatures of Late Pleistocene fluvial incision in an Alpine landscape

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Leith, Kerry; Fox, Matthew; Moore, Jeffrey R.

2018-02-01

Uncertainty regarding the relative efficacy of fluvial and glacial erosion has hindered attempts to quantitatively analyse the Pleistocene evolution of alpine landscapes. Here we show that the morphology of major tributaries of the Rhone River, Switzerland, is consistent with that predicted for a landscape shaped primarily by multiple phases of fluvial incision following a period of intense glacial erosion after the mid-Pleistocene transition (∼0.7 Ma). This is despite major ice sheets reoccupying the region during cold intervals since the mid-Pleistocene. We use high-resolution LiDAR data to identify a series of convex reaches within the long-profiles of 18 tributary channels. We propose these reaches represent knickpoints, which developed as regional uplift raised tributary bedrock channels above the local fluvial baselevel during glacial intervals, and migrated upstream as the fluvial system was re-established during interglacial periods. Using a combination of integral long-profile analysis and stream-power modelling, we find that the locations of ∼80% of knickpoints in our study region are consistent with that predicted for a fluvial origin, while the mean residual error over ∼100 km of modelled channels is just 26.3 m. Breaks in cross-valley profiles project toward the elevation of former end-of-interglacial channel elevations, supporting our model results. Calculated long-term uplift rates are within ∼15% of present-day measurements, while modelled rates of bedrock incision range from ∼1 mm/yr for low gradient reaches between knickpoints to ∼6-10 mm/yr close to retreating knickpoints, typical of observed rates in alpine settings. Together, our results reveal approximately 800 m of regional uplift, river incision, and hillslope erosion in the lower half of each tributary catchment since 0.7 Ma.

Aeolian and fluvial processes in dryland regions: the need for integrated studies

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Belnap, Jayne; Munson, Seth M.; Field, Jason P.

2011-01-01

Aeolian and fluvial processes play a fundamental role in dryland regions of the world and have important environmental and ecological consequences from local to global scales. Although both processes operate over similar spatial and temporal scales and are likely strongly coupled in many dryland systems, aeolian and fluvial processes have traditionally been studied separately, making it difficult to assess their relative importance in drylands, as well as their potential for synergistic interaction. Land degradation by accelerated wind and water erosion is a major problem throughout the world's drylands, and although recent studies suggest that these processes likely interact across broad spatial and temporal scales to amplify the transport of soil resources from and within drylands, many researchers and land managers continue to view them as separate and unrelated processes. Here, we illustrate how aeolian and fluvial sediment transport is coupled at multiple spatial and temporal scales and highlight the need for these interrelated processes to be studied from a more integrated perspective that crosses traditional disciplinary boundaries. Special attention is given to how the growing threat of climate change and land-use disturbance will influence linkages between aeolian and fluvial processes in the future. We also present emerging directions for interdisciplinary needs within the aeolian and fluvial research communities that call for better integration across a broad range of traditional disciplines such as ecology, biogeochemistry, agronomy, and soil conservation.

Presencia de propágulos de hongos de micorriza arbuscular en muestras de hojarasca alrededor de dos especies arbóreas en un bosque húmedo tropical

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Raúl Hernando Posada Almanza

2001-01-01

Full Text Available En ecosistemas de bosques, las micorrizas juegan un papel determinante en la dinámica poblacional de las diferentes especies de plantas coexistentes; por tal motivo su cuantificación y la determinación de la variabilidad en cuanto a la distribución de las diferentes formas de propágulos alrededor de especies presentes en bosque húmedo tropical, es importante dentro del contexto del ciclaje de nutrientes. Los resultados mostraron grandes variaciones cuantitativas en cuanto a presencia de esporas de hongos de micorriza arbuscular (HMA en muestras frescas; su abundancia y distribución parece estar relacionada con la humedad del suelo y con la especie vegetal alrededor de la cual fueron colectadas. Se encontraron diferencias significativas (pbosque húmedo tropical de los llanos Orientales colombianos.

Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone

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Anderson, P.B.; Chidsey, T.C.; Ryer, T.A.

1997-01-01

East-central Utah has world-class outcrops of dominantly fluvial-deltaic Turonian to Coniacian aged strata deposited in the Cretaceous foreland basin. The Ferron Sandstone Member of the Mancos Shale records the influences of both tidal and wave energy on fluvial-dominated deltas on the western margin of the Cretaceous western interior seaway. Revisions of the stratigraphy are proposed for the Ferron Sandstone. Facies representing a variety of environments of deposition are well exposed, including delta-front, strandline, marginal marine, and coastal-plain. Some of these facies are described in detail for use in petroleum reservoir characterization and include permeability structure.

Sediment dynamics in the Rhine catchment : Quantification of fluvial response to climate change and human impact

NARCIS (Netherlands)

Erkens, G.

2009-01-01

Fluvial systems are strongly responsive to changes in climate and land use — but take their time to show it. Accurate prediction of the timing and degree of future fluvial response requires comprehensive understanding of fluvial response in the past. This PhD-thesis studied the response of the river

Riqueza y abundancia de aves en bosques ribereños de diferentes anchos en la microcuenca del río Sesesmiles, Copán, Honduras

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Inty T Arcos

2008-03-01

Full Text Available El estudió se realizó en la microcuenca del río Sesesmiles, Departamento de Copán, Honduras. El propósito fue explorar el efecto del ancho de franja de los bosques ribereños sobre la riqueza y abundancia de especies de aves que visitan estos bosques. Se encontraron 1 294 aves pertenecientes a 145 especies en bosques ribereños. La diversidad de aves estuvo ligada al ancho de franja de los bosques ribereños: se encontró mayor número de especies e individuos, en anchos iguales o mayores a 50 m. Las especies pertenecientes al grupo alimenticio de los insectívoros y nectarívoros fueron las más abundantes en las franjas ribereñas. Todas las especies de aves identificadas dependen de los bosques ribereños y responden al ancho del bosque; aún las especies más generalistas tienen algún grado de dependencia a las franjas ribereñas más anchas. Para conservar las poblaciones de aves en los paisajes agrícolas fragmentados es de suma importancia mantener franjas ribereñas que sean mayores a 50 m de ancho y que brinden suficientes habitas y recursos.Richness and abundance of birds in riparian forest belts of varied breadths at the Sesesmiles river microwatershed, Copan, Honduras. Riparian forests protect many species of plants and animals. We studied bird communities in riparian forest belts of the Sesesmiles river microwatershed, Copan, Honduras (140o 43’ 12" - 140o 58’ 35" N, 88o 53’ 23" - 89o 14’ 17" W. The main goal was to explore the effects of belt breadth on the richness and abundance of avian species visiting these forests. We selected 20 belts, and randomly established 30 observation points to monitor bird presence in the dry (March-April 2005 and rainy (June-July 2005 season (N= 60 observations. A total of 1 294 birds belonging to 145 species were recorded. Bird diversity was significantly correlated to the breadth of the riparian belts, with a greater number of species and individuals in belts 50 m wide or wider

GOEMORFOLOGIA FLUVIAL DA BACIA HIDROGRÁFICA DO RIO DE ONDAS

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Ossifleres Silva Damasceno

2011-10-01

Full Text Available Os estudos de Geomorfologia Fluvial para analise de Bacias Hidrográficas vêm tendo nos últimos tempos grande importância, tanto para se conhecer as características de determinadas bacias como para se planejar o uso de tais recursos. Neste sentido, este trabalho foi efetuado no intuito de somar aos estudos anteriormente executados nessa bacia, levantando algumas características geomorfológicas, o uso e ocupação atual. Palavras-chaves: geomorfologia fluvial, hidrografia, agricultura irrigada.

Surficial geological tools in fluvial geomorphology: Chapter 2

Science.gov (United States)

Jacobson, Robert B.; O'Connor, James E.; Oguchi, Takashi

2016-01-01

Increasingly, environmental scientists are being asked to develop an understanding of how rivers and streams have been altered by environmental stresses, whether rivers are subject to physical or chemical hazards, how they can be restored, and how they will respond to future environmental change. These questions present substantive challenges to the discipline of fluvial geomorphology, especially since decades of geomorphologic research have demonstrated the general complexity of fluvial systems. It follows from the concept of complex response that synoptic and short-term historical views of rivers will often give misleading understanding of future behavior. Nevertheless, broadly trained geomorphologists can address questions involving complex natural systems by drawing from a tool box that commonly includes the principles and methods of geology, hydrology, hydraulics, engineering, and ecology.

Fluvial system response to Late Devensian (Weichselian) aridity, Baston, Lincolnshire, England

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Briant, Rebecca M.; Coope, G. Russell; Preece, Richard C.; Keen, David H.; Boreham, Steve; Griffiths, Huw I.; Seddon, Mary B.; Gibbard, Philip L.

2004-07-01

Little is known about the impact of Late Devensian (Weichselian) aridity on lowland British landscapes, largely because they lack the widespread coversand deposits of the adjacent continent. The concentration of large interformational ice-wedge casts in the upper part of many Devensian fluvial sequences suggests that fluvial activity may have decreased considerably during this time. The development of optically stimulated luminescence (OSL) dating enables this period of ice-wedge cast formation to be constrained for the first time in eastern England, where a marked horizon of ice-wedge casts is found between two distinctive dateable facies associations. Contrasts between this horizon and adjacent sediments show clear changes in environment and fluvial system behaviour in response to changing water supply, in line with palaeontological evidence. In addition to providing chronological control on the period of ice-wedge formation, the study shows good agreement of the radiocarbon and OSL dating techniques during the Middle and Late Devensian, with direct comparison of these techniques beyond 15 000 yr for the first time in Britain. It is suggested that aridity during the Late Devensian forced a significant decrease in fluvial activity compared with preceding and following periods, initiating a system with low peak flows and widespread permafrost development. Copyright

Lacustrine-fluvial interactions in Australia's Riverine Plains

Science.gov (United States)

Kemp, Justine; Pietsch, Timothy; Gontz, Allen; Olley, Jon

2017-06-01

Climatic forcing of fluvial systems has been a pre-occupation of geomorphological studies in Australia since the 1940s. In the Riverine Plain, southeastern Australia, the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world. Surficial sediments and landforms exceed 140,000 yr in age, and geomorphological change recorded in the fluvial, fluvio-lacustrine and aeolian features have provided a well-studied record of Quaternary environmental change over the last glacial cycle. The region includes the Willandra Lakes, whose distinctive lunette lakes preserve a history of water-level variations and ecological change that is the cornerstone of Australian Quaternary chronostratigraphy. The lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the Australian continent. To date, the lake-level and palaeochannel records in the Lachlan-Willandra system have not been fully integrated, making it difficult to establish the regional significance of hydrological change. Here, we compare the Willandra Lakes environmental record with the morphology and location of fluvial systems in the lower Lachlan. An ancient channel belt of the Lachlan, Willandra Creek, acted as the main feeder channel to Willandra Lakes before channel avulsion caused the lakes to dry out in the late Pleistocene. Electromagnetic surveys, geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion. Single grain optical dating of floodplain sediments indicates that sedimentation in the new Middle Billabong Palaeochannel had commenced before 18.4 ± 1.1 ka. A second avulsion shifted its upper reaches to the location of the present Lachlan River by 16.2 ± 0.9 ka. The timing of these events is consistent with palaeohydrological records reconstructed from Willandra Lakes and with the record of

The Gediz River fluvial archive : A benchmark for Quaternary research in Western Anatolia

NARCIS (Netherlands)

Maddy, D.; Veldkamp, A.; Demir, T.; van Gorp, W.; Wijbrans, J.R.; van Hinsbergen, D.J.J.; Dekkers, M.J.; Schreve, D.; Schoorl, J.M.; Scaife, R.; Stemerdink, C.; van der Schriek, T.; Bridgland, D.R.; Aytaç, A.S.

2017-01-01

The Gediz River, one of the principal rivers of Western Anatolia, has an extensive Pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of Asia during the Quaternary. In this paper we review our work on the Quaternary Gediz River

Diversidad y mecanismos de dispersión de árboles de la Isla Gorgona y de los bosques húmedos tropicales del Pacífico colombo-ecuatoriano

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Yockteng Roxana

1998-03-01

Full Text Available En este trabajo se hizo una comparación entre la flora de la isla Gorgona (Colombia y la de los bosques del Chocó biogeográfico (Colombia y Ecuador. Para esta comparación se utilizaron curvas de acumulación de especies e índices de riqueza y diversidad, tanto publicadas por diferentes autores o generadas a partir de los inventarios florísticos originales. La riqueza del bosque de la isla Gorgona calculada a partir de curvas especie-área y del índice de diversidad de Shannon fue inferior a la de varios bosques colombianos y ecuatorianos en las tierras bajas del continente. Adicionalmente, el índice de equitabilidad de Shannon en cinco bosques del Pacífico colombo-ecuatoriano fue mayor que el de la isla Gorgona, lo cual sugiere que en los bosques continentales las especies están representados por un número similar de individuos. La ornitocoria fue el mecanismo de dispersión más importante en la isla Gorgona (49.7%, en forma similar a lo encontrado para las islas Galápagos en Ecuador (60 % y para la isla biogeográfica del bosque nublado de la Serranía de la Macuira, Guajira, en el norte de Colombia (51 %. En contraste, la dispersión por mamíferos fue el mecanismo más importante para las especies de árboles del bosque continental de Cabo Corrientes, de Bajo Calima (Colombia y los Tuxtlas (México. A pesar de que los bosques de la Isla Gorgona, no son especialmente ricos en especies, cumplen una importante función protectora de los ecosistemas de coral que rodean la isla. Una reducción de la cobertura boscosa tendría como consecuencia un aumento de las tasa de erosión y avalanchas que afectarían gravemente los ecosistemas marinos, en particular los arrecifes de coral.The flora of the continental Island of Gorgona (Colombia and that of the forests on the Chocó biogeographical region of Colombia and Ecuador were compared with species-area curves and species diversity indexes, either previously published or calculated using

El impacto del huracán Dean sobre la estructura y composición arbórea de un bosque manejado en Quintana Roo, México

OpenAIRE

Navarro-Martínez, Angélica; Durán-García, Rafael; Méndez-González, Martha

2012-01-01

Los huracanes son considerados como uno de los factores más determinantes de la estructura y composición de muchos bosques tropicales. En Quintana Roo, estos fenómenos naturales son tan frecuentes que forman parte de la dinámica natural del bosque. El 21 de agosto de 2007, en el centro-sur del Estado, ocurrió el huracán Dean, que afectó alrededor de 900,000 ha de la selva mediana subperennifolia. En este estudio se cuantifican los daños ocasionados sobre la vegetación y se analizan los cambio...

Evidence of anthropogenic tipping points in fluvial dynamics in Europe

Science.gov (United States)

Notebaert, Bastiaan; Broothaerts, Nils; Verstraeten, Gert

2018-05-01

In this study the occurrence of thresholds in fluvial style changes during the Holocene are discussed for three different catchments: the Dijle and Amblève catchments (Belgium) and the Valdaine Region (France). We consider tipping points to be a specific type of threshold, defined as relatively rapid and irreversible changes in the system. Field data demonstrate that fluvial style has varied in all three catchments over time, and that different tipping points can be identified. An increase in sediment load as a result of human induced soil erosion lead to a permanent change in the Dijle floodplains from a forested peaty marsh towards open landscape with clastic deposition and a well-defined river channel. In the Valdaine catchment, an increase in coarse sediment load, caused by increased erosion in the mountainous upper catchment, altered the floodplains from a meandering pattern to a braided pattern. Other changes in fluvial style appeared to be reversible. Rivers in the Valdaine were prone to different aggradation and incision phases due to changes in peak water discharge and sediment delivery, but the impact was too low for these changes to be irreversible. Likewise the Dijle River has recently be prone to an incision phase due to a clear water effect, and also this change is expected to be reversible. Finally, the Amblève River did not undergo major changes in style during the last 2000 to 5000 years, even though floodplain sedimentation rates increased tenfold during the last 600 years. Overall, these examples demonstrate how changes in fluvial style depend on the crossing of thresholds in sediment supply and water discharge. Although changes in these controlling parameters are caused by anthropogenic land use changes, the link between those land use changes and changes in fluvial style is not linear. This is due to the temporal variability in landscape connectivity and sediment transport and the non-linear relationship between land use intensity and soil

La vegetación como indicador de la Geomorfología Fluvial

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Juan José Neiff

2005-11-01

Full Text Available Aguas abajo de la confluencia con el río Paraguay, el Paraná se expande en una ancha planicie lateral que, durante las inundaciones extraordinarias completa un área 2-10 veces mayor que el área ocupada por las aguas en los períodos de bajantes extraordinarias, en los que el curso queda aislado de la planicie inundable. El propósito de esta contribución es presentar las características más salientes de este tramo entrelazado del río, usando las unidades de paisaje y los tipos de vegetación, como indicadores de las formas del relieve. Imágenes satelitales Landsat TM5 y TM7 procesadas con el SIG IDRISI, de la inundación extrema de 1998 y de la sequía extrema de 2001, fueron usadas para la clasificación de los tipos de vegetación, usando el criterio propuesto por CET (Clasificación Ecológica de Tierras. Observaciones de campo fueron realizadas en ambas fases hidrológicas para obtener la posición topográfica de las unidades de vegetación y de los ensambles de comunidades vegetales. Nosotros encontramos que los albardones están ocupados por tipos de bosques, mientras que los bañados y cuerpos de aguas someros están cubiertos por plantas herbáceas y que las praderas flotantes de vegetación flotante libre, como el aguapé, crecen en lagos conectados al río una o más veces en el año. La vegetación acuática del curso principal es muy pobre como consecuencia del flujo del río y las fluctuaciones de nivel del agua. Sólo pequeñas manchas de carrizo se encontraron creciendo en barras de arena. La interrelación entre la vegetación y las formas del relieve es muy dinámica, con cambios drásticos en períodos de décadas o aún de pocos años, dependiendo del caudal y de la carga de sólidos transportados. En otro sentido, la vegetación fluvial tiene un importante rol en la fijación de depósitos fluviales y como núcleos de acreción en las barras o para entender la obstrucción de pequeños cursos de agua en la planicie

Geological aspects of paleoseismicity and archaeosismology in the fluvial alluvial Rimac valley

OpenAIRE

Jacay, Javier

2017-01-01

The sedimentary fill of the Rimac River fluvial-alluvial plain (Upper Miocene-Quaternary) consists of a thick sequence of unconsolidated material that corresponds to fluvial deposits. A record of seismotectonic activity is presentedin the sedimentary levels of fine facie within numerous paleoseismic structures such as contoured layers, pseudonodules, load figures, and material injections. Additionally, wall inclination and collapse, as well as displacement and partialfracturing, and pavement ...

Natural radionuclide behaviour in the fluvial environment

International Nuclear Information System (INIS)

Murray, A.S.; Olley, J.M.; Wallbrink, P.J.

1992-01-01

Variable concentrations of uranium and thorium series nuclides and 7 Be have been measured in soils and sediments. Strong correlations between 226 Ra and thorium series nuclides were found in sediments but not in soils. Laboratory measurements suggest the correlations arise from particle size and density dependent transport, and transport-related abrasion of iron oxide coatings. These correlations are characteristic of the sampled location, and provide a method for identifying the source areas which dominate the fluvial nuclide flux, and by implication, the associated sediment flux. Cosmogenic 7 Be (half-life 53 d) also contributes to nuclide fluxes. Over an 18 month period, individual rainstorms increased the 7 Be soil inventory by 10% on average. Dry precipitation contributed less than 10% to the total. Most 7 Be was retained within the top few millimetres of soil. It is deduced that 7 Be presence in fluvial sediments indicates a significant surface source contribution to the overall nuclide and sediment flux. (author)

Interacciones entre semillas y escarabajos del estiércol (scarabaeinae) en un bosque tropical seco

OpenAIRE

Julissa Ocampo-Castillo; Ellen Andresen

2018-01-01

Los escarabajos del estiércol (Scarabaeinae) son insectos importantes en muchos ecosistemas terrestres por susfunciones ecológicas, derivadas del comportamiento de remover las heces de vertebrados. Este grupo de insectoses particularmente abundante en los bosques tropicales (BT). Sus funciones ecológicas han sido principalmenteestudiadas en los BT húmedos, existiendo poca información para los BT secos. Se realizaron experimentos de campoen la Estación de Biología de Chamela (Jalisco, México) ...

The influence of fluvial reservoir architecture on geothermal energy production in Hot Sedimentary Aquifers

NARCIS (Netherlands)

Willems, C.J.L.

2014-01-01

Currently six geothermal doublets are realized in the WNB. Five of these doublets target the same Lower Cretaceous fluvial sandstone interval, the Nieuwerkerk Formation. About 40 exploration licences are granted. Many of them also have sandstones in the same fluvial interval, the Nieuwerkerk

A Field Exercise in Fluvial Sediment Transport.

Science.gov (United States)

Tharp, Thomas M.

1983-01-01

Describes an investigation which introduces the mathematical principles of stream hydraulics and fluvial sediment in a practical context. The investigation has four stages: defining hydrology of the stream; defining channel hydraulics in a study reach; measuring grain size; and calculating transportable grain size and comparing measure stream-bed…

Diversidad y mecanismos de dispersión de árboles de la Isla Gorgona y de los bosques húmedos tropicales del Pacífico colombo-ecuatoriano

OpenAIRE

Yockteng Roxana; Jaime Cavelier

1998-01-01

En este trabajo se hizo una comparación entre la flora de la isla Gorgona (Colombia) y la de los bosques del Chocó biogeográfico (Colombia y Ecuador). Para esta comparación se utilizaron curvas de acumulación de especies e índices de riqueza y diversidad, tanto publicadas por diferentes autores o generadas a partir de los inventarios florísticos originales. La riqueza del bosque de la isla Gorgona calculada a partir de curvas especie-área y del índice de diversidad de Shannon fue inferior a l...

Interacciones entre semillas y escarabajos del estiércol (scarabaeinae en un bosque tropical seco

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Julissa Ocampo-Castillo

2018-01-01

Full Text Available Los escarabajos del estiércol (Scarabaeinae son insectos importantes en muchos ecosistemas terrestres por susfunciones ecológicas, derivadas del comportamiento de remover las heces de vertebrados. Este grupo de insectoses particularmente abundante en los bosques tropicales (BT. Sus funciones ecológicas han sido principalmenteestudiadas en los BT húmedos, existiendo poca información para los BT secos. Se realizaron experimentos de campoen la Estación de Biología de Chamela (Jalisco, México durante la temporada de lluvias para cuantificar la remociónde heces por los escarabajos del estiércol y para evaluar sus interacciones con semillas durante la remoción deheces en un BT seco. A las 48 h la remoción de heces fue total; 71% de las semillas artificiales fueron enterradas entre0.5 y 30 cm de profundidad, y el 29% quedaron sobre la superficie pero dispersadas horizontalmente entre 1 y 150cm. El establecimiento de plántulas a partir del banco de semillas se vio favorecido por la presencia de heces y laactividad de los escarabajos del estiércol. Comparando nuestros resultados con aquellos obtenidos en bosquesNeotropicales húmedos, concluimos que en el BT seco estudiado las funciones ecológicas de los Scarabaeinae enla época de lluvias son similares a lo registrado en BT húmedos.

Efecto de la tala de Podocarpus glomeratus (Podocarpaceae sobre la estructura de un bosque de neblina en los Andes (Cochabamba, Bolivia

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Ariel Isaías Ayma-Romay

2011-07-01

Full Text Available En el presente trabajo fueron analizados los efectos de la tala sobre la estructura, composición y la regeneración natural de un bosque andino de neblina. Se instalaron 40 parcelas de 707 m2 para medir individuos >10 cm DAP y sub-parcelas de 5 m2 para evaluar la regeneración de individuos <10 cm DAP y de 1 m2 para evaluar el banco de semillas. Se evaluó la densidad y cobertura de todos los árboles. Se realizó un análisis cluster para establecer las categorías de cobertura de dosel y un análisis de componentes principales para determinar su asociación con la densidad de diferentes especies de plántulas. La tala ha modificado la cobertura (p= <0,001 generando doseles de poco a fuertemente intervenidos. Los claros de dosel favorecen a las heliófitas (Myrsine pseudocrenata, Vallea stipularis, Nectandra sp., Trichilia hirta, Miconia theaezans, algunas esciófitas que requieren luz en clases avanzadas (Podocarpus glomeratus y Myrcianthes osteomeloides y otros arbustos (Solanaceae, Verbenaceae y otras. Por otra parte, algunas esciófitas reducen su densidad en doseles inter- venidos (Weinmannia microphylla, Condalia weberbaueri, Blepharocalix salicifolius y Styloceras columnare. El manejo del bosque debe mantener la cobertura de individuos > 60 cm DAP, la creación de reservas en bosques maduros y prácticas de facilitación para el crecimiento de especies de árboles claves.

Fluvial facies reservoir productivity prediction method based on principal component analysis and artificial neural network

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Pengyu Gao

2016-03-01

Full Text Available It is difficult to forecast the well productivity because of the complexity of vertical and horizontal developments in fluvial facies reservoir. This paper proposes a method based on Principal Component Analysis and Artificial Neural Network to predict well productivity of fluvial facies reservoir. The method summarizes the statistical reservoir factors and engineering factors that affect the well productivity, extracts information by applying the principal component analysis method and approximates arbitrary functions of the neural network to realize an accurate and efficient prediction on the fluvial facies reservoir well productivity. This method provides an effective way for forecasting the productivity of fluvial facies reservoir which is affected by multi-factors and complex mechanism. The study result shows that this method is a practical, effective, accurate and indirect productivity forecast method and is suitable for field application.

Diversidad de árboles y arbustos en fragmentos de bosque seco tropical en río Hato, Panamá

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Omar R Lopez

2015-01-01

Full Text Available En fragmentos de bosque seco tropical en Río Hato, Panamá, estudiamos la composición florística según los árboles y arbustos. Establecimos 61 parcelas de 100 m2 distribuidas de forma aleatoria, totalizando 0.61 hectáreas. En cada unidad de muestreo medimos todos los individuos presentes con un DAP >5.0 cm. Encontramos un total de 52 especies de árboles representadas en veinticinco familias, de las cuales Fabaceae, Burseraceae, Myrtaceae y Rubiaceae aportan mayor número de especies (~35%. La especie Sloanea terniflora (Sessé & Moç. ex DC. Standl se encontró en más del 60.6% de los cuadrantes estudiados y resultó además ser la especie con mayor dominancia relativa (23%, seguida de Anacardium excelsum (Bertero & Balb. ex Kunth Skeels, que con solo quince individuos de grandes diámetros presentó una dominancia relativa del 10%. La diversidad promedio reveló índices intermedios (3.13 índice de Shannon. A pesar del bajo número de especies en comparación con otros BS-T de la región, los fragmentos en Río Hato conservan elementos florísticos de importancia ecológica y para la conservación de los bosques secos. Garcinia madruno (Kunth Hammel, una de las especies más abundante es clave en la producción de frutos para la fauna. Otras especies de importancia son Manilkara sapota (L. P. Royen y Copaifera aromatica Dwyer, las cuales aún son utilizadas como recurso maderero. Es prioritario para Panamá establecer estrategias de conservación que salvaguarden estos fragmentos como fuente de especies del bosque seco tropical y refugio para la vida silvestre.

Gold-bearing fluvial and associated tidal marine sediments of Proterozoic age in the Mporokoso Basin, northern Zambia

Science.gov (United States)

Andrews-Speed, C. P.

1986-07-01

The structurally defined Mporokoso Basin contains up to 5000 m of continental and marine clastic sediments and minor silicic volcanics which together form the Mporokoso Group. These rocks overlie unconformably a basement of silicic-intermediate igneous rocks and accumulated within the interval 1830-1130 Ma. This sedimentological study was restricted to the eastern end of the basin and was part of an assessment of the potential for palaeoplacer gold in the Mporokoso Group. At the base of the Mporokoso Group, the Mbala Formation consists of 1000-1500 m of purple sandstones and conglomerates deposited in a braided-stream system overlain by 500-1000 m of mature quartz arenites deposited in a tidal marine setting. A general coarsening-upward trend exists within the fluvial sediments. Sandy, distal braided-stream facies passes upwards into more proximal conglomeratic facies. In proximal sections, poorly sorted conglomerates form the top of the coarsening-up sequence which is 500-700 m thick. The overlying fluvial sediments fine upwards. The tidal marine sandstones at the top of the Mbala Formation resulted from reworking of fluvial sediments during a marine transgression. Well-exposed sections with fluvial conglomerates were studied in detail. Individual conglomerate bodies form sheets extending for hundreds of metres downstream and at least one hundred metres across stream, with little sign of deep scouring or channelling. They are generally matrix-supported. The whole fluvial sequence is characterised by a paucity of mud or silt. These conglomerates were deposited by large velocity, sheet flows of water which transported a bed-load of pebbles and sand. Most fine material settling out from suspension was eroded by the next flow. The great lateral and vertical extent and the uniformity of the fluvial sediments suggest that the sediments accumulated over an unconfined alluvial plain and that the tectonic evolution of the source area was relatively continuous and not

LA VEGETACIÓN TERRESTRE DEL BOSQUE MONTANO DE LANCHURÁN (PIURA, PERÚ

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Rasal Maria

2012-06-01

Full Text Available Entre los meses de febrero y marzo de 2008 se realizaron inventarios que permitieronconocer el estado actual de la composición florística y la estructura de la vegetacióndel bosque montano neotropical de Lanchurán (4o38'S, 79o42'W, provinciade Ayabaca, región Piura, Perú. Se siguió el método propuesto por Gentry paramuestreo de plantas leñosas en dos sitios, Los Molinos y La Antena, para un totalde 0.5 ha; éstos fueron escogidos por sus características fisiográficas y florísticas.En ambos sitios el análisis de suelo reveló niveles bajos de materia orgánica,nitrógeno y potasio y niveles medios de fósforo asimilable. Se registraron, en elsitio Los Molinos, 399 individuos/0.25 ha con diámetro a la altura del pecho ≥ 2.5cm, correspondientes a 41 especies, 33 géneros y 25 familias, a lo que se suma unavegetación herbácea conformada por 82 especies, 75 géneros y 48 familias; y enel sitio La Antena, 86 especies, 67 géneros y 41 familias. Las familias presentescon mayor valor ecológico son comunes a la mayoría de los bosques montanos delnorte y noroeste del Perú, entre ellas Asteraceae, Lauraceae, Melastomataceae,Rubiaceae y Solanaceae. Para el sitio Los Molinos el Área Basal fue 89.23 m2,destacando la Lauraceae con la mayores valores de cobertura relativa, Índice deValor de Importancia y Valor de Importancia para la Familia con 38.9, 73.1 y 70.8,respectivamente. Se destaca la acción antrópica sobre la diversidad florística enambos sitios de estudio.

La géoarchéologie fluviale

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Gilles Arnaud-Fassetta

2008-03-01

Full Text Available Les recherches des hydrogéomorphologues ont des applications nombreuses dans le vaste champ des sciences géoarchéologiques. Elles fournissent des réponses précises sur la façon dont l’environnement des anciens lieux de passage et de vie humaine a évolué. Le propos n’est pas seulement de définir les causes des grands changements environnementaux, mais aussi de juger de la vulnérabilité sociétale face aux contraintes hydroclimatiques. Pour cela, les méthodes d’étude doivent nécessairement prendre en compte les trois facettes de la géomorphologie fluviale : la paléohydrographie, la paléohydrologie et la paléohydraulique. La pertinence de cette approche est montrée en milieu rural et urbain dans les plaines deltaïques du Rhône (France du Sud et de l’Isonzo (Italie du Nord.Current research led by hydrogeomorphologists has numerous applications in the vast field of geoarchaeological sciences. It brings precise answers on environmental characteristics around the ancient places of passage and human life. The goal is not only to define the causes of global environmental changes, but also to precise the links between river dynamics and human societies in terms of fluvial risk. Therefore, the studied methods should simultaneously take into account the three facets of the fluvial geomorphology, i.e., the palaeohydrography, the palaeohydrology, and the palaeohydraulics. The pertinence of this combinatorial approach is deduced from the work of the author led both in rural and urban areas of the deltaic plains of the Rhône (South of France and Isonzo (northern Italy rivers.

Fluvial processes and channel morphometry of the upper Orashi ...

African Journals Online (AJOL)

Fluvial processes and channel morphometry of the upper Orashi basin in ... of channel equilibrium between morphology and hydrology, the Orashi channel is not well ... Drainage basins, watershed morphology, morphometric analysis, Nigeria ...

History of the Oral and Maxillofacial Surgery Residency Program at Universidad el Bosque, Bogotá, Colombia.

Science.gov (United States)

Castro-Núñez, Jaime

2012-01-01

The formal training of oral and maxillofacial surgeons in Colombia started in 1958 at Hospital Sanjos6, thanks to the titanic work of Waldemar Wilhelm, a German-born surgeon who settled in BogotA in 1950. Today there are seven institutions in Colombia that offer residency programs in oral and maxillofacial surgery. The aim of this article is to describe the history of the Oral and Maxillofacial Surgery Residency Program at Universidad El Bosque in Bogota.

Fluvial Channel Networks as Analogs for the Ridge-Forming Unit, Sinus Meridiani, Mars

Science.gov (United States)

Wilkinson, M. J.; du Bois, J. B.

2010-01-01

Fluvial models have been generally discounted as analogs for the younger layered rock units of Sinus Meridiani. A fluvial model based on the large fluvial fan provides a possibly close analog for various features of the sinuous ridges of the etched, ridge-forming unit (RFU) in particular. The close spacing of the RFU ridges, their apparently chaotic orientations, and their organization in dense networks all appear unlike classical stream channel patterns. However, drainage patterns on large fluvial fans low-angle, fluvial aggradational features, 100s of km long, documented worldwide by us provide parallels. Some large fan characteristics resemble those of classical floodplains, but many differences have been demonstrated. One major distinction relevant to the RFU is that channel landscapes of large fans can dominate large areas (1.2 million km2 in one S. American study area). We compare channel morphologies on large fans in the southern Sahara Desert with ridge patterns in Sinus Meridiani (fig 1). Stream channels are the dominant landform on large terrestrial fans: they may equate to the ubiquitous, sinuous, elongated ridges of the RFU that cover areas region wide. Networks of convergent/divergent and crossing channels may equate to similar features in the ridge networks. Downslope divergence is absent in channels of terrestrial upland erosional landscapes (fig. 1, left), whereas it is common to both large fans (fig. 1, center) and RFU ridge patterns (fig 1, right downslope defined as the regional NW slope of Sinus Meridiani). RFU ridge orientation, judged from those areas apparently devoid of impact crater control, is broadly parallel with the regional slope (arrow, fig. 1, right), as is mean orientation of major channels on large fans (arrow, fig. 1, center). High densities per unit area characterize fan channels and martian ridges reaching an order of magnitude higher than those in uplands just upstream of the terrestrial study areas fig. 1. In concert with

Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation

Science.gov (United States)

Wilkinson, M. Justin; Herridge, A.

2013-01-01

Imagery and MOLA data were used in an analysis of the ridge-forming rock unit (RFU) exposed in Sinus Meridiani (SM). This unit shows parallels at different scales with fluvial sedimentary bodies. We propose the terrestrial megafan as the prime analog for the RFU, and likely for other members of the layered units. Megafans are partial cones of fluvial sediment, with radii up to hundreds of km. Although recent reviews of hypotheses for the RFU units exclude fluvial hypotheses [1], inverted ridges in the deserts of Oman have been suggested as putative analogs for some ridges [2], apparently without appreciating The wider context in which these ridges have formed is a series of megafans [3], a relatively unappreciated geomorphic feature. It has been argued that these units conform to the megafan model at the regional, subregional and local scales [4]. At the regional scale suites of terrestrial megafans are known to cover large areas at the foot of uplands on all continents - a close parallel with the setting of the Meridiani sediments at the foot of the southern uplands of Mars, with its incised fluvial systems leading down the regional NW slope [2, 3] towards the sedimentary units. At the subregional scale the layering and internal discontinuities of the Meridiani rocks are consistent, inter alia, with stacked fluvial units [4]. Although poorly recognized as such, the prime geomorphic environment in which stream channel networks cover large areas, without intervening hillslopes, is the megafan [see e.g. 4]. Single megafans can reach 200,000 km2 [5]. Megafans thus supply an analog for areas where channel-like ridges (as a palimpsest of a prior landscape) cover the intercrater plains of Meridiani [6]. At the local, or river-reach scale, the numerous sinuous features of the RFU are suggestive of fluvial channels. Cross-cutting relationships, a common feature of channels on terrestrial megafans, are ubiquitous. Desert megafans show cemented paleo-channels as inverted

Estructura y estado de conservación de los bosques de Prosopis flexuosa D.C. (Fabaceae, subfamilia: Mimosoideae en el noreste de Mendoza (Argentina Structure and conservative condition of the Prosopis flexuosa D.C. (Fabaceae, subfamily: Mimosoideae woodlands in northeast Mendoza (Argentina

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JUAN AGUSTÍN ALVAREZ

2006-03-01

Full Text Available La recomendación de normas de manejo que regulen el uso de los recursos forestales debe estar basada en el conocimiento de la estructura y dinámica de los mismos. El objetivo de este trabajo fue conocer la estructura poblacional de las principales unidades boscosas del bosque de Prosopis flexuosa del noreste de Mendoza, sus condiciones sanitarias y su potencial productivo. Se muestrearon un total de 1.471 algarrobos en las cuatro unidades boscosas más representativas. La densidad total de algarrobos fue la siguiente: bosque semicerrado de P. flexuosa con Atriplex lampa y Lycium tenuispinosum en valles intermédanos (Bosque 1: 181 árboles ha-1, bosque abierto de P. flexuosa con Trichomaria usillo y Suaeda divaricata en ondulaciones (Bosque 2: 155 árboles ha-1, bosque abierto de P. flexuosa con T. usillo (Bosque 3: 233 árboles ha-1 y bosque abierto de P. flexuosa con A. lampa en ondulaciones suaves (Bosque 4: 215 árboles ha-1. El análisis de componentes principales de la estructura diamétrica agrupó los sitios relevados en las distintas unidades boscosas según la proporción de árboles de diámetro basal mayor a 25 cm. Los sitios del Bosque 1 (mayor proporción de árboles grandes, se separaron de los sitios con mayor proporción árboles pequeños (bosques 2 y 4. Debido al hábito de crecimiento de los algarrobos, la cantidad de productos maderables de estos bosques es baja. Además, P. flexuosa presenta en el área un porcentaje alto de individuos con más de dos fustes, la forma en muchos casos es decumbente y la altura de los fustes es menor a un metro. Por lo tanto, el potencial forestal del bosque es bajo y el posible aprovechamiento debería realizarse a escala local, considerando la inclusión de otras actividades complementarias en zonas establecidas para tal finThe recommendation of management rules that regulate the use of forest resources must be based on the knowledge of the structure and dynamics of forests. This work

A model of plant strategies in fluvial hydrosystems

NARCIS (Netherlands)

Bornette, G.; Tabacchi, E.; Hupp, C.; Puijalon, S.; Rostan, J.C.

2008-01-01

1. We propose a model of plant strategies in temperate fluvial hydrosystems that considers the hydraulic and geomorphic features that control plant recruitment, establishment and growth in river floodplains. 2. The model describes first how the disturbance gradient and the grain-size of the river

TASAS DE RECAMBIO FLORÍSTICO DE GÉNEROS EN BOSQUES MONTANOS DEL NEOTRÓPICO

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López Wilson

2010-06-01

Full Text Available Se evaluó la tasa de recambio fl orístico en bosques de alta montaña (por encima delos 1500 m.s.n.m. al nivel taxonómico de géneros en dos áreas geográfi cas y surelación con factores espaciales, climáticos y históricos. Las áreas defi nidas fueron:1 Colombia, la cual se defi ne para los sitios en este país localizados alrededor delEcuador geográfi co; y 2 Neotrópico: sitios externos a Colombia más distantesdel Ecuador geográfi co. Las preguntas a responder fueron: ¿Qué tan comparablesson las tasas de recambio fl orístico de géneros en las diferentes áreas geográfi cas?y ¿Qué tan similares son los factores que controlan la distribución de géneros?La diversidad beta fue diferente según el área geográfi ca. La variación climática,representada por la precipitación, fue más relevante a escala del neotrópico, mientrasque la variación altitudinal lo fue a escala de Colombia. Los patrones de distribuciónal nivel de género, fueron poco congruentes con los reportados a nivel de especiesen bosques montanos del neotrópico, especialmente cuando se consideraron datoscercanos alrededor del Ecuador geográfi co en Colombia.

The origin of dose distributions in fluvial sediments, and the prospect of dating single grains from fluvial deposits using optically stimulated luminescence

International Nuclear Information System (INIS)

Olley, J.M.; Caitcheon, G.G.; Roberts, R.G.

1999-01-01

We examine the causes of the asymmetric distributions of dose observed from measurements of the optically stimulated luminescence emitted by small aliquots of fluvial quartz, and deduce that the asymmetry arises as a result of samples being composed of a mix of mainly well bleached grains with grains that were effectively unbleached at the time of deposition. We demonstrate that the shapes of the dose distributions can be used to assess the likelihood that aliquots consist only of grains that were well-bleached at the time of deposition. The more asymmetric the distribution, the greater the probability that the aliquots with the lowest dose most closely represent the true burial dose. Single grains with differing doses are present in each of the samples examined, and the population with the lowest dose gives an optical age consistent with the expected burial age. This result implies that the beta-dose heterogeneity in these deposits is small, and that the effects of micro-dosimetric variations on optical dating of individual grains are not significant for these samples. We demonstrate that single-grain dating of fluvial material is possible and practicable using standard Risoe optical dating equipment, and we conclude that application of a new regenerative-dose protocol to single grains of quartz, using the lowest dose population to estimate the burial dose, is the best available means of obtaining reliable luminescence ages for heterogeneously bleached fluvial sediments

A geologic approach to field methods in fluvial geomorphology

Science.gov (United States)

Fitzpatrick, Faith A.; Thornbush, Mary J; Allen, Casey D; Fitzpatrick, Faith A.

2014-01-01

A geologic approach to field methods in fluvial geomorphology is useful for understanding causes and consequences of past, present, and possible future perturbations in river behavior and floodplain dynamics. Field methods include characterizing river planform and morphology changes and floodplain sedimentary sequences over long periods of time along a longitudinal river continuum. Techniques include topographic and bathymetric surveying of fluvial landforms in valley bottoms and describing floodplain sedimentary sequences through coring, trenching, and examining pits and exposures. Historical sediment budgets that include floodplain sedimentary records can characterize past and present sources and sinks of sediment along a longitudinal river continuum. Describing paleochannels and floodplain vertical accretion deposits, estimating long-term sedimentation rates, and constructing historical sediment budgets can assist in management of aquatic resources, habitat, sedimentation, and flooding issues.

Implications from Sedimentary records in Fluvial Terraces for Geomorphological Evolution in the Puli Basin, Taiwan

NARCIS (Netherlands)

Tseng, C.H.; Wenske, D.; Böse, M.; Reimann, T.; Lüthgens, C.; Frechen, Manfred

2013-01-01

Fluvial terraces play an important role for research on previous geomorphic processes as their sediments can record various sedimentation stages. In the mountains of central Taiwan, however, the formation time of sediments in the Puli Basin is still unclear. In this study, we investigate the fluvial

Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

Science.gov (United States)

Apel, Heiko; Martínez Trepat, Oriol; Nghia Hung, Nguyen; Thi Chinh, Do; Merz, Bruno; Viet Dung, Nguyen

2016-04-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either a fluvial or pluvial flood hazard, studies of a combined fluvial and pluvial flood hazard are hardly available. Thus this study aims to analyse a fluvial and a pluvial flood hazard individually, but also to develop a method for the analysis of a combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as an example. In this tropical environment the annual monsoon triggered floods of the Mekong River, which can coincide with heavy local convective precipitation events, causing both fluvial and pluvial flooding at the same time. The fluvial flood hazard was estimated with a copula-based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. The pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data and a stochastic rainstorm generator. Inundation for all flood scenarios was simulated by a 2-dimensional hydrodynamic model implemented on a Graphics Processing Unit (GPU) for time-efficient flood propagation modelling. The combined fluvial-pluvial flood scenarios were derived by adding rainstorms to the fluvial flood events during the highest fluvial water levels. The probabilities of occurrence of the combined events were determined assuming independence of the two flood types and taking the seasonality and probability of

ESTRUCTURA ESPACIAL DE EPÍFITAS VASCULARES EN DOS LOCALIDADES DE BOSQUE ALTOANDINO, PAMPLONA, COLOMBIA

OpenAIRE

CAROL BIBIANA ROJAS FLÓREZ; LUIS ROBERTO SÁNCHEZ MONTAÑO

2015-01-01

Las epífitas vasculares son un componente importante de los bosques altoandinos. Para determinar su composición en la región nororiental y si la incidencia de luz afecta su distribución, se estudiaron por un año dos localidades, Monteadentro y Escorial; ubicadas sobre la cordillera oriental de los Andes Colombianos entre 2950- 3000m. En cada una se hicieron 10 parcelas de 10x10m, censándose los forófitos y diferenciando: Estrato1, desde la base- 5m; Estrato2, de 5- 10 m, y Estrato3, 10 m- en ...

Ephemeral-fluvial sediments as potential hydrocarbon reservoirs. Vol. 1: Sedimentology

Energy Technology Data Exchange (ETDEWEB)

Taylor, K.S.

1994-12-31

Although reservoirs formed from ephemeral-fluvial sandstones have previously been considered relatively simple, unresolved problems of sandbody correlation and production anomalies demonstrate the need for improved understanding of their internal complexity. Outcropping ephemeral-fluvial systems have been studied in order to determine the main features and processes occurring in sand-rich ephemeral systems and to identify which features will be of importance in a hydrocarbon reservoir. The Lower Jurassic Upper Moenave and Kayenta Formations of south-eastern Utah and northern Arizona comprise series of stacked, sand-dominated sheet-like palaeochannels suggestive of low sinuosity, braided systems. Low subsidence rates and rapid lateral migration rates enabled channels to significantly modify their widths during high discharge. (author)

CARACTERIZACIÓN FENOLÓGICA DE BOSQUES TROPICALES CADUCIFOLIOS USANDO INFORMACIÓN ESPECTRAL: EXPERIMENTOS CON COMPONENTES

OpenAIRE

Marcos Casiano; Fernando Paz

2014-01-01

La caracterización de la fenología de la vegetación, particularmente la asociada a los bosques tropicales caducifolios, permite predecir los impactos del cambio climático y de los intercambios de carbono y agua entre la atmósfera y la vegetación, por lo que es importante modelarla. Existen diferentes métodos experimentales para caracterizar la fenología de la vegetación, sin embargo, el uso de sensores remotos permite caracterizaciones fenológicas de bajo costo y eficientes. No obstante lo an...

Global effects of agriculture on fluvial dissolved organic matter

DEFF Research Database (Denmark)

Graeber, Daniel; Boëchat, Iola; Encina, Francisco

2015-01-01

Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter...

Fluvial processes on Mars: Erosion and sedimentation

Science.gov (United States)

Squyres, Steven W.

1988-01-01

One of the most important discoveries of the Mariner 9 and Viking missions to Mars was evidence of change of the Martian surface by the action of liquid water. From the standpoint of a Mars Rover/Sample Return Mission, fluvial activity on Mars is important in two ways: (1) channel formation has deeply eroded the Martian crust, providing access to relatively undisturbed subsurface units; and (2) much of the material eroded from channels may have been deposited in standing bodies of liquid water. The most striking fluvial erosion features on Mars are the outflow channels. A second type of channel apparently caused by flow of liquid water is the valley systems. These are similar to terrestial drainage systems. The sedimentary deposits of outflow channels are often difficult to identfy. No obvious deposits such as deltaic accumulations are visible in Viking images. Another set of deposits that may be water lain and that date approx. from the epoch of outflow channels are the layered deposits in the Valles Marineris. From the standpoint of a Mars Rover/Sample Return mission, the problem with all of these water-lain sediments is their age, or rather the lack of it.

Fluvial geomorphology: where do we go from here?

Science.gov (United States)

Smith, Derald G.

1993-07-01

The evolution of geomorphology and in particular, fluvial geomorphology, is at a crossroads. Currently, the discipline is dismally organized, without focus or direction, and is practised by individualists who rarely collaborate in numbers significant enough to generate major research initiatives. If the discipline is to mature and to prosper, we must make some very difficult decisions that will require major changes in our ways of thinking and operating. Either the field stays in its current operational mode and becomes a backwater science, or it moves forward and adopts the ways of the more competitive sectors of the earth and biosciences. For the discipline to evolve, fluvial geomorphologists must first organize an association within North America or at the international level. The 3rd International Geomorphology Conference may be a start, but within that organization we must develop our own divisional and/or regional organizations. Within the Quaternary geology/geomorphology divisions of the Geological Socieity of America (GSA), Association of American Geographers (AAG), American Geophysical Union (AGU) and British Geomorphology Research Group (BGRG) the voice of fluvial geomorphology is lost in a sea of diverse and competitive interests, though there is reason for hope resulting from some recent initiatives. In Canada, we have no national geomorphology organization per se; our closest organization is Canqua (Canadian Quaternary Association). Next, fluvial researchers must collaborate, by whatever means, to develop "scientific critical mass" in order to generate ideas and long-range goals of modest and major scientific importance. These projects will help secure major research funding without which, research opportunities will diminish and initiating major new research will become nearly impossible. Currently, we are being surpassed by the glaciologists, remote sensors, ecologists, oceanographers, climatologists-atmospheric researchers and some Quaternary

Fluvial archives, a valuable record of vertical crustal deformation

Science.gov (United States)

Demoulin, A.; Mather, A.; Whittaker, A.

2017-06-01

The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature of crustal deformation and its history. In recent decades, geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens. Here, we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions (the effects of horizontal deformation are not addressed). Channel long profiles have received considerable attention in the literature, and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives, before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady-state characteristics. Then, we review the literature dealing with the transient response of rivers to tectonic perturbation, through the production of knickpoints propagating through the drainage network. Inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories. Finally, we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes. As well as the erosional imprint of tectonic forcing, sedimentary deposits, such as fluvial terrace staircases, are also considered as a classical component of tectonic geomorphology. We show that these studies have recently benefited from rapid advances in dating techniques, allowing more reliable reconstruction of incision histories and estimation of incision rates. The combination of progress in the understanding of transient river profiles and larger, more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace

Model Projections of Future Fluvial Sediment Delivery to Major Deltas Under Environmental Change

Science.gov (United States)

Darby, S. E.; Dunn, F.; Nicholls, R. J.; Cohen, S.; Zarfl, C.

2017-12-01

Deltas are important hot spots for climate change impacts on which over half a billion people live worldwide. Most of the world's deltas are sinking as a result of natural and anthropogenic subsidence and due to eustatic sea level rise. The ability to predict rates of delta aggradation is therefore critical to assessments of the extent to which sedimentation can potentially offset sea level rise, but our ability to make such predictions is severely hindered by a lack of insight into future trends of the fluvial sediment load supplied to their deltas by feeder watersheds. To address this gap we investigate fluvial sediment fluxes under future environmental change for a selection (47) of the world's major river deltas. Specifically, we employed the numerical model WBMsed to project future variations in mean annual fluvial sediment loads under a range of environmental change scenarios that account for changes in climate, socio-economics and dam construction. Our projections indicate a clear decrease (by 34 to 41% on average, depending on the specific scenario) in future fluvial sediment supply to most of the 47 deltas. These reductions in sediment delivery are driven primarily by anthropogenic disturbances, with reservoir construction being the most influential factor globally. Our results indicate the importance of developing new management strategies for reservoir construction and operation.

Influence of fluvial sandstone architecture on geothermal energy production

NARCIS (Netherlands)

Willems, C.J.L.; Maghami Nick, Hamidreza M.; Weltje, G.J.; Donselaar, M.E.; Bruhn, D.F.

2015-01-01

Fluvial sandstone reservoirs composed of stacked meander belts are considered as potential geothermal resources in the Netherlands. Net-to-gross, orientation and stacking pattern of the channel belts is of major importance for the connectivity between the injection and production well in such

Reservoirs as hotspots of fluvial carbon cycling in peatland catchments.

Science.gov (United States)

Stimson, A G; Allott, T E H; Boult, S; Evans, M G

2017-02-15

Inland water bodies are recognised as dynamic sites of carbon processing, and lakes and reservoirs draining peatland soils are particularly important, due to the potential for high carbon inputs combined with long water residence times. A carbon budget is presented here for a water supply reservoir (catchment area~9km 2 ) draining an area of heavily eroded upland peat in the South Pennines, UK. It encompasses a two year dataset and quantifies reservoir dissolved organic carbon (DOC), particulate organic carbon (POC) and aqueous carbon dioxide (CO 2 (aq)) inputs and outputs. The budget shows the reservoir to be a hotspot of fluvial carbon cycling, as with high levels of POC influx it acts as a net sink of fluvial carbon and has the potential for significant gaseous carbon export. The reservoir alternates between acting as a producer and consumer of DOC (a pattern linked to rainfall and temperature) which provides evidence for transformations between different carbon species. In particular, the budget data accompanied by 14 C (radiocarbon) analyses provide evidence that POC-DOC transformations are a key process, occurring at rates which could represent at least ~10% of the fluvial carbon sink. To enable informed catchment management further research is needed to produce carbon cycle models more applicable to these environments, and on the implications of high POC levels for DOC composition. Copyright © 2016 Elsevier B.V. All rights reserved.

Variability in fluvial geomorphic response to anthropogenic disturbance

Science.gov (United States)

Verstraeten, Gert; Broothaerts, Nils; Van Loo, Maarten; Notebaert, Bastiaan; D'Haen, Koen; Dusar, Bert; De Brue, Hanne

2017-10-01

Humans have greatly impacted the processes and intensities of erosion, sediment transport and storage since the introduction of agriculture. In many regions around the world, accelerated floodplain sedimentation can be related to increases in human pressure on the environment. However, the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non-linear. Here, we review a number of case studies from contrasting environmental settings in the European loess belt, the Eastern Mediterranean mountain ranges and the eastern USA. Detailed field-based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year, as well as the use of pollen and sediment provenance techniques, show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established. Slope-channel (dis)connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact. This coupling can be related to characteristics of human pressure such as its duration, intensity and spatial patterns, but also to the geomorphic and tectonic setting. Furthermore, internal feedback mechanisms, such as those between erosion and soil thickness, further complicate the story. All these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions. Hence, only unique patterns of fluvial geomorphic response can be identified. As a result, unravelling the human impact from current-day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge. This has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains, deltas and the marine

SISTEMA FLUVIAL E PLANEJAMENTO LOCAL NO SEMIÁRIDO

Directory of Open Access Journals (Sweden)

Jonas Otaviano Praça de Souza

2012-01-01

Full Text Available El presente estudio analiza un sistema fluvial semiárido y sus características físicas, centrándose en los procesos geomorfológicos y las formas resultantes, sino también en las relaciones con las actividades humanas, con el fin de utilizar dichos datos en la planificación local. La encuesta se llevó a cabo en el municipio de Belém do São Francisco, en Pernambuco, mesorregión del São Francisco en la cuenca del arroyo Mulungu, lugar expuesto a un clima semi-árido con lluvias de verano, y la cobertura del suelo con un predominio de la caatinga arbustiva abierta. Se tomó como procedimiento metodológico la cartografía geomorfológica a diferentes escalas y con diferentes énfasis, para evaluar la relación jerárquica entre los distintos compartimentos, sustratos geológicos y formas de uso de la tierra. De la información espacial obtenida en los distintos niveles de la cartografía detallada del sistema fluvial, se realizó una evaluación ambiental de la zona, teniendo como base la dinámica erosiva/deposicional a lo largo del canal y su relación con sus bancos. Se concluyó que las formas de acumulación en la llanura aluvial exhiben controles de origen antropogénico, vinculados a los tipos tradicionales de uso del suelo en la cuenca. Estos controles, como la construcción de represas a lo largo del canal, actúan cambiando a los procesos de creación de nuevas morfologías de depósito en el sistema fluvial, que a su vez comienzan a redefinir los tipos usos de la zona.

Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam

Science.gov (United States)

Apel, H.; Trepat, O. M.; Hung, N. N.; Chinh, D. T.; Merz, B.; Dung, N. V.

2015-08-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by

Inventario y evaluación de primates y amenazas para sus poblaciones en bosque montano de la Región Huánuco, Perú

Directory of Open Access Journals (Sweden)

Rolando Aquino

2015-06-01

Full Text Available El estudio estuvo orientado al inventario y evaluación de primates e identificar las amenazas para sus poblaciones en bosque montano de la Región Huánuco,  un área poco explorado con respecto a la  fauna silvestre. De Junio a Julio y de Setiembre a Octubre del 2014, fueron conducidos censos por transecto en puntos de muestreo correspondientes a las microcuencas de los ríos Chontayacu y Chinchao y cuenca alta del río Huallaga. En 618 km de longitud recorrida fueron registrados 47 grupos pertenecientes a cinco especies, siendo las más comunes Alouatta seniculus (15 grupos y Lagothrix flavicauda  (13 grupos. L. flavicauda fue observada únicamente en la Microcuenca del río Chontayacu,  y Ateles chamek  en la Cuenca alta del río Huallaga. En el área de estudio, los primates viven en parches de bosques primario y residual, excepto en el Chontayacu, donde el bosque primario es todavía denso y extenso. La densidad poblacional fue más alta para L. flavicauda (20,8 indiv./km2 y más baja para Sapajus macrocephalus (2,7 indiv./km2. Entre las actividades observadas, la deforestación para la agricultura y ganadería constituye la principal  amenaza para la supervivencia de primates, en particular en la Microcuenca del río Chinchao y Cuenca alta del río Huallaga.

Distribución espacial de la macrofauna edáfica en bosque mesófilo, bosque secundario y pastizal en la reserva La Cortadura, Coatepec, Veracruz, México Spatial distribution of soil macrofauna in cloud forest, secondary forest and grassland in La Cortadura reserve, Coatepec, Veracruz, Mexico

Directory of Open Access Journals (Sweden)

Isis N. De la Rosa

2012-03-01

Full Text Available La conversión de un área de bosque para la agricultura o el pastoreo homogeniza las propiedades del suelo y las comunidades de macroinvertebrados. Este trabajo estudió si la diversidad (H', densidad y heterogeneidad espacial (tamaño de parche de macroinvertebrados de hojarasca y suelo se recuperan en una secuencia sucesional pastizal (Pas-bosque secundario (Bsec-bosque mesófilo maduro (BMM. En el sustrato hojarasca se observó un gradiente de aumento para todas las variables estudiadas en la secuencia Pas-Bsec-BMM. Sin embargo, este patrón no se presentó en el suelo, ya que la mayor diversidad y densidad (por taxón y total se encontraron en el Bsec. Mediante un análisis de variografía, en la hojarasca se encontraron distribuciones espaciales heterogéneas de los macroinvertebrados en ambos bosques, mientras que en el pastizal la distribución fue homogénea, lo que apoya la idea de que el disturbio va acompañado de una homogenización espacial de las comunidades de macroinvertebrados, pero la restructuración espacial se recupera en la sucesión temprana. En el suelo de los 3 sitios, la distribución de todas las variables fue en parches (5 a 60 m de diámetro, pero no se encontró disminución en la heterogeneidad espacial predicha para la secuencia Pas-Bsec-BMM.The conversion of forest to agriculture or pasture homogenizes soil properties, including the communities of macroinvertebrates. This study examined whether the diversity (H', density and spatial heterogeneity (patch size of litter and soil macroinvertebrate recover through the secondary successional sequence pasture (Pas-secondary forest (Bsec- mature cloud forest (BMM. In the litter an increasing gradient for all variables was observed through the successional sequence. However, this pattern was not present in the soil, where the highest diversity and density (per taxon and total were found in the Bsec. Using variography, we found heterogeneous spatial distributions of

Suspended sediment transport trough a large fluvial-tidal channel network

Science.gov (United States)

Wright, Scott A.; Morgan-King, Tara L.

2015-01-01

The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they

Diversidad de tres gremios de hormigas en cafetales de sombra, de sol y bosques de Risaralda

OpenAIRE

RIVERA, LEONARDO; ARMBRECHT, INGE

2005-01-01

Durante 2001-2002 se realizó un estudio de la mirmecofauna (Hymenoptera: Formicidae) en cafetales del municipio de Apía (Risaralda), para evaluar el impacto que las técnicas modernas de cultivo de café tienen sobre la biodiversidad asociada. Se seleccionaron 12 fincas clasificadas en tres sistemas de manejo de sombra de café (tratamientos) y un control compuesto por parches de bosque. Se ubicaron 20 parcelas de 1 m² por finca en las cuales se realizó colecta manual de hormigas en hojarasca y ...

La Segunda Guerra Mundial y la “crisis de producción” en los bosques mexicanos

OpenAIRE

Christopher Boyer

2012-01-01

Este artículo muestra que la Segunda Guerra Mundial representó un parteaguas para los bosques mexicanos. La guerra creó una inmensa demanda de productos forestales por parte de los Aliados y México respondió mediante la implementación de un sistema que denomino “el aprovechamiento de la crisis”. El nuevo régimen productivo puso a un lado la política forestal existente, que favorecía el manejo cuidadoso de los recursos naturales, y la sustituyó por la tala comercial casi desmedida. La guerra t...

Plantas asociadas a los bosques de Abies guatemalensis (Pinaceae del occidente de Guatemala Plants associated to Abies guatemalensis (Pinaceae forests in Western Guatemala

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José Vicente Martínez Arévalo

2013-03-01

Full Text Available Hay una carencia de información detallada sobre la composición y estructura de las comunidades montanas guatemaltecas. El objetivo del estudio fue contribuir al conocimiento de la flora de bosques de abeto (Abies guatemalensis, para esto se hizo el levantamiento florístico en bosques de abeto del occidente de Guatemala. Se encontraron 119 especies, 92 géneros, 50 familias en cuatro divisiones. Las familias más numerosas fueron: Asteraceae, Poaceae, Rosaceae, Lamiaceae, Apiaceae y Solanaceae y los géneros más abundantes Salvia, Alchemilla y Bidens. Las especies se ubicaron en cuatro estratos, 33 en el herbáceo inferior, 49 en el herbáceo superior, 30 en arbustos y siete en árboles. Se hace énfasis en la contribución del estudio al conocimiento de la flora de bosques de A. guatemalensis y la necesidad de otros similares en los demás bosques de esta especie, que sirva para fomentar su conocimiento y conservación. Se consideraron seis grupos de distribución geográfica, el principal es del centro de México a Centroamérica con 67% de especies. Se realiza una comparación fitogeográfica y de composición florística, con otras áreas de Abies de Guatemala y México. Se propone que a pesar de haber familias y géneros comunes, que proporcionan la estructura general entre los bosques de abeto, se deben considerar las particularidades florísticas de cada área, en el manejo y conservación influidas por suelo, latitud y microclima.The fragments of Abies guatemalensis forests in Western Guatemala are the reservoirs of plant species that have been poorly documented, missing the opportunity to expand the knowledge of the local flora and its use in conservation planning. To assess this, a floristic study was done in areas between 2 950-3 360masl in Western Guatemala between 2010-2011. Ten locations were sampled: in each a 500m² plot was surveyed, and plants were classified in four strata by plant height (0.05-30m. A total of 119 species

Mapping Variability in the Medusae Fossae Formation: Yardang Morphologies, Fluvial Reworking, and Crater Depth to Diameter Ratios

Science.gov (United States)

Khuller, A. R.; Kerber, L.

2017-12-01

The Medusae Fossae Formation (MFF) is a voluminous, fine-grained deposit thought to be of pyroclastic origin. While it contains widespread, well-preserved inverted fluvial features, its pervasive cover of dust means that little is known about its composition, and indirect means must be used to characterize its material properties. This project aims to correlate fluvial features in the Western MFF with other indicators of material strength: yardang morphology and crater depth-to-diameter ratios. For this work, Context Camera (CTX) images were used to map features of fluvial origin (inverted channels, sinuous ridges, alluvial fans). The presence of rounded, meso-yardangs in close proximity to fluvial features was also mapped. Crater depth-diameter (d/D) ratios (for craters 1-512km) were analyzed using a global Mars crater database (Robbins and Hynek, 2012) as a proxy for material strength. Approximately 1400 fluvial segments were mapped, with the most populous cluster located in Aeolis and Zephyria Plana. Rounded meso-yardangs were found to be common in areas that also have fluvial features. In agreement with previous work (Barlow, 1993), MFF craters were found to have a greater d/D ratio (0.0523) than the global mean (0.0511). Ratios between MFF lobes differ significantly, providing insight into the heterogeneity of induration within the formation. The deepest craters are found in Eumenides Dorsum and the shallowest in Aeolis Planum, consistent with a greater degree of induration and reworking in the western part of the formation where the fluvial features and "salt-playa" meso-yardangs are found. It also suggests that Eumenides, which is the tallest MFF outcrop, could also be the least compacted. The presence of long, complex, and sometimes overlapping branching networks imply multiple relative episodes of channel formation. Rounded meso-yardangs, which are associated with salt playa surfaces on Earth, provide additional evidence for the presence of liquid water

LOS BOSQUES Y LA MINERÍA DEL NORTE CHICO, S. XIX.: UN MITO EN LA REPRESENTACIÓN DEL PAISAJE CHILENO

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Pablo Camus Gayan

2004-12-01

Full Text Available Diversos estudios han planteado que los privilegios que el denuncio de bosques otorgaba a los mineros habrían provocado el deterioro irreversible del ambiente del Norte Chico. El presente artículo pretende relativizar esta tesis planteando que el paisaje era semiárido antes de la expansión de la minería y proponiendo la hipótesis que la discusión para derogar los denuncios fue un conflicto entre mineros y agricultores por definir la propiedad de los bosques, pero de los que se encontraban más al sur.Several studies had stablished that the privilege that the claim or denounce of forests that have been given to the miners had caused the irreversible damage to the land of the Norte Chico. This article pretends to diminish this thesis, arguing that the lands was semi dry o semi desertic before the expantion of mines suggesting the hipothesis that the argument to stop with the claim was a struggle betwenn the miners and the farmers to define the property of the forets, but the ones further south.

Volcanogenic Fluvial-Lacustrine Environments in Iceland and Their Utility for Identifying Past Habitability on Mars

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Claire Cousins

2015-02-01

Full Text Available The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite, and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides. This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing.

Volcanogenic fluvial-lacustrine environments in iceland and their utility for identifying past habitability on Mars.

Science.gov (United States)

Cousins, Claire

2015-02-16

The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing.

Study on detailed geological modelling for fluvial sandstone reservoir in Daqing oil field

Energy Technology Data Exchange (ETDEWEB)

Zhao Hanqing; Fu Zhiguo; Lu Xiaoguang [Institute of Petroleum Exploration and Development, Daqing (China)

1997-08-01

Guided by the sedimentation theory and knowledge of modern and ancient fluvial deposition and utilizing the abundant information of sedimentary series, microfacies type and petrophysical parameters from well logging curves of close spaced thousands of wells located in a large area. A new method for establishing detailed sedimentation and permeability distribution models for fluvial reservoirs have been developed successfully. This study aimed at the geometry and internal architecture of sandbodies, in accordance to their hierarchical levels of heterogeneity and building up sedimentation and permeability distribution models of fluvial reservoirs, describing the reservoir heterogeneity on the light of the river sedimentary rules. The results and methods obtained in outcrop and modem sedimentation studies have successfully supported the study. Taking advantage of this method, the major producing layers (PI{sub 1-2}), which have been considered as heterogeneous and thick fluvial reservoirs extending widely in lateral are researched in detail. These layers are subdivided into single sedimentary units vertically and the microfacies are identified horizontally. Furthermore, a complex system is recognized according to their hierarchical levels from large to small, meander belt, single channel sandbody, meander scroll, point bar, and lateral accretion bodies of point bar. The achieved results improved the description of areal distribution of point bar sandbodies, provide an accurate and detailed framework model for establishing high resolution predicting model. By using geostatistic technique, it also plays an important role in searching for enriched zone of residual oil distribution.

Variables and potential models for the bleaching of luminescence signals in fluvial environments

Science.gov (United States)

Gray, Harrison J.; Mahan, Shannon

2015-01-01

Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

Sistema de gestión de recursos culturales y naturales santuario Bosque de Pomac, Lambayeque, Perú

OpenAIRE

Arias Salcedo, Ricardo Víctor

2012-01-01

La presente investigación formula, analiza y desarrolla una estructura metodológica que valide un sistema de indicadores que, en clave de ordenamiento territorial, examine el territorio del Santuario Histórico Bosque de Pomac, unidad de protección de alta prioridad. Una vez ordenado territorialmente se pretende generar una propuesta de sistema de gestión y uso de los recursos culturales y naturales e incorporarse como una base técnica e instrumental de planificación sostenible. Tesis (Mast...

A multi-scale approach of fluvial biogeomorphic dynamics using photogrammetry.

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Hortobágyi, Borbála; Corenblit, Dov; Vautier, Franck; Steiger, Johannes; Roussel, Erwan; Burkart, Andreas; Peiry, Jean-Luc

2017-11-01

Over the last twenty years, significant technical advances turned photogrammetry into a relevant tool for the integrated analysis of biogeomorphic cross-scale interactions within vegetated fluvial corridors, which will largely contribute to the development and improvement of self-sustainable river restoration efforts. Here, we propose a cost-effective, easily reproducible approach based on stereophotogrammetry and Structure from Motion (SfM) technique to study feedbacks between fluvial geomorphology and riparian vegetation at different nested spatiotemporal scales. We combined different photogrammetric methods and thus were able to investigate biogeomorphic feedbacks at all three spatial scales (i.e., corridor, alluvial bar and micro-site) and at three different temporal scales, i.e., present, recent past and long term evolution on a diversified riparian landscape mosaic. We evaluate the performance and the limits of photogrammetric methods by targeting a set of fundamental parameters necessary to study biogeomorphic feedbacks at each of the three nested spatial scales and, when possible, propose appropriate solutions. The RMSE varies between 0.01 and 2 m depending on spatial scale and photogrammetric methods. Despite some remaining difficulties to properly apply them with current technologies under all circumstances in fluvial biogeomorphic studies, e.g. the detection of vegetation density or landform topography under a dense vegetation canopy, we suggest that photogrammetry is a promising instrument for the quantification of biogeomorphic feedbacks at nested spatial scales within river systems and for developing appropriate river management tools and strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Variations in dung beetles assemblages (Coleoptera: Scarabaeidae within two rain forest habitats in French Guiana Variaciones de las agregaciones de escarabajos coprófagos (Coleoptera: Scarabaeidae en dos hábitats del bosque tropical en la Guayana Francesa

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François Feer

2013-06-01

Full Text Available The structure of dung beetle communities inhabiting tropical forests are known to be sensitive to many kinds of environmental changes such as microclimate related to vegetation structure. I examined Scarabaeinae assemblages in two sites of undisturbed high forest and two sites of low forest forming a transitional zone with the open habitat of an inselberg in French Guiana. Sampling was made with pitfall and flight interception traps during 2003 and 2004. The driest and warmest conditions characterized the low forest sites. Across two years we obtained 2 927 individuals from 61 species with pitfall traps and 1 431 individuals from 85 species with flight interception traps. Greater species richness and abundance characterized all sites sampled with pitfall traps during 2003 more than 2004. In 2003 no differences were detected among sites by rarefaction analyses. In 2004 the species richest high forest site was significantly different from one of the low forest sites. For both years Clench model asymptotes for species richness were greater in high forest than in low forest sites. For both years, mean per-trap species richness, abundance and biomass among high forest sites were similar and higher than in low forest sites, especially where the lowest humidity and the highest temperature were recorded. Within the two low forest sites, species richness and abundance recorded during the second year, decreased with distance to edge. Different dominant roller species characterized the pitfall samples in one site of low forest and in other sites. Small variations in microclimatic conditions correlated to canopy height and openness likely affected dung beetle assemblages but soil depth and the presence of large mammals providing dung resource may also play a significant role.Es conocido que la estructura de las comunidades de escarabajos coprófagos que habitan los bosques tropicales es sensible a diferentes tipos de cambios ambientales tales como el

Efecto de plantaciones de pino en la artropofauna del suelo de un bosque Altoandino

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Alba Lucía León-Gamboa

2010-09-01

Full Text Available Los artrópodos del suelo son un componente fundamental de los ecosistemas de bosque, ya que participan en la fragmentación de los residuos orgánicos previa a la descomposición. Esta función es más valuable en ambientes de altura, donde las bajas temperaturas limitan la dinámica de los procesos biológicos. Sin embargo, uno de los problemas más comunes en las montañas colombianas ha sido el reemplazo de vegetación nativa por plantaciones de pino. Los efectos sobre los artrópodos del suelo aún son poco conocidos. En un remanente de bosque Altoandino (Embalse del Neusa-Colombia con una plantación adyacente de unos 50 años (aprox. 900 has, fue evaluada la composición, riqueza y abundancia de artrópodos en los estratos superficial (S orgánico (O y mineral (A del suelo, para establecer las diferencias asociadas con la transformación del uso del suelo. Se utilizaron trampas "Pitfall" para registrar el movimiento de fauna epígea, y embudos Berlese para estimar la densidad de fauna de los horizontes O y A. Se calcularon los índices de Shannon y Simpson para estimar la diversidad en diferentes lugares y horizontes, además fue evaluada la estructura trófica de la comunidad. Se recolectaron 38 306 individuos en el bosque y 17 386 en la plantación, principalmente distribuidos en los taxa Collembola, (42.4%, Acari (27%, Diptera (17.6% y Coleoptera (4.6%. Las diferencias más importantes se dieron en la superficie, donde la movilización en bosque (86 individuos/día casi triplicó la movilización en la plantación (33 individuos/día. Las diferencias en la composición se dieron en los taxa Collembola, Araneae, Hemiptera, Homoptera e Hymenoptera. La dinámica de la riqueza y abundancia a lo largo del año tuvo picos significativos en el bosque, no observados en la plantación. La estructura trófica fue dominada por saprófagos (75%, depredadores (14% y fitófagos (9%, pero en dos estratos de la plantación de pino (S y O no se dio

Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities

Science.gov (United States)

Marchetti, Mauro

2002-05-01

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area. This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating. In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations. Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the

Analytically based forward and inverse models of fluvial landscape evolution during temporally continuous climatic and tectonic variations

Science.gov (United States)

Goren, Liran; Petit, Carole

2017-04-01

Fluvial channels respond to changing tectonic and climatic conditions by adjusting their patterns of erosion and relief. It is therefore expected that by examining these patterns, we can infer the tectonic and climatic conditions that shaped the channels. However, the potential interference between climatic and tectonic signals complicates this inference. Within the framework of the stream power model that describes incision rate of mountainous bedrock rivers, climate variability has two effects: it influences the erosive power of the river, causing local slope change, and it changes the fluvial response time that controls the rate at which tectonically and climatically induced slope breaks are communicated upstream. Because of this dual role, the fluvial response time during continuous climate change has so far been elusive, which hinders our understanding of environmental signal propagation and preservation in the fluvial topography. An analytic solution of the stream power model during general tectonic and climatic histories gives rise to a new definition of the fluvial response time. The analytic solution offers accurate predictions for landscape evolution that are hard to achieve with classical numerical schemes and thus can be used to validate and evaluate the accuracy of numerical landscape evolution models. The analytic solution together with the new definition of the fluvial response time allow inferring either the tectonic history or the climatic history from river long profiles by using simple linear inversion schemes. Analytic study of landscape evolution during periodic climate change reveals that high frequency (10-100 kyr) climatic oscillations with respect to the response time, such as Milankovitch cycles, are not expected to leave significant fingerprints in the upstream reaches of fluvial channels. Linear inversion schemes are applied to the Tinee river tributaries in the southern French Alps, where tributary long profiles are used to recover the

Presencia de hongos micorrízicos arbusculares (HMA en especies representativas del bosque seco tropical del litoral ecuatoriano

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Ivette Chiquito Noboa

2018-02-01

Full Text Available Los hongos micorrízicos arbusculares (HMA son microorganismos que mantienen una relación simbiótica mutualista con las raíces de las plantas. El bosque seco tropical contiene abundantes especies de interés silvícola, sin embargo, en Ecuador se desconoce las relaciones simbióticas de los HMA con los árboles que representan el bosque seco. El propósito de este estudio fue aislar e identificar la presencia de HMA en determinadas especies vegetales de este nicho ecológico del Ecuador. Las muestras de suelo y raíces se recolectaron en la época húmeda entre los meses de marzo y abril del 2017. Los porcentajes de micorrización encontrados fueron los siguientes: Cochlospermun vitifolium (Bototillo 80.8%, Triplaris cumingiana (Fernán Sánchez 71.7%, Albizia multiflora (Compoño 70.0%, Tecoma castanifolia (Moyuyo de montaña 68.6%, Bursera graveolens (Palo Santo 68.3%, Sapindus saponaria (Jaboncillo 67.5%, Croton wagneri (Purga 65.0%, Ceiba trichistandra (Ceibo 62.2%. Todas las plantas muestreadas presentaron una densidad media de esporas por 100 gr de suelo, pero Triplaris cumingiana (Fernán Sánchez obtuvo una mayor esporulación a pesar de presentar la misma densidad media.

Diversidad de la familia Orchidaceae en los bosques montanos de San Ignacio (Cajamarca, Perú

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Gloria Calatayud

2013-05-01

Full Text Available La insuficiente información sobre la flora, específicamente sobre la familia Orchidaceae y la inminente desaparición de los bosques en la Vertiente Oriental del río Chinchipe (San Ignacio, Cajamarca, fueron las razones suficientes que motivaron a realizar la presente investigación. La evaluación se realizó en cuatro localidades de la provincia San Ignacio (Cajamarca, durante el año 2000, con 27 cuadrantes de 500 m², distribuidos cada 100 m de altitud, desde los 800 hasta los 2700 m, el método de muestreo fue aleatorio. Según el índice de diversidad de Shannon–Wiener, la zona de estudio posee un alto grado de diversidad (entre H’= 5,93 en Selva Andina y H’= 4,02 en Camaná, gracias al buen estado de conservación de los bosques y a la topografía de la zona. Las localidades de Camaná-Crucero (173,55 son menos disímiles por presentar hábitats similares. Selva Andina (969,619 es la localidad más disímil con el grupo Crucero-Camaná-Nuevo Mundo, la cual a los 2700 m presenta un alto endemismo. Para las localidades evaluadas se reportan 205 especies distribuidas en 58 géneros, los cuales son reportes nuevos para la zona, 15 son registros nuevos para Perú, ocho de éstas dejan de ser endémicas para Ecuador. Se reporta por primera vez para Perú el género Chrysocycnis, y dos especies nuevas para la ciencia Sarcoglottis sp. y Maxillaria sp.

Patrones de distribución espacial de árboles en un bosque estacionalmente seco del Parque Nacional Cerros de Amotape en el noroeste peruano

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Reynaldo Linares-Palomino

2013-05-01

Full Text Available Se realizó un estudio de los patrones de distribución espacial de cuatro especies de árboles características de los bosques secos del Parque Nacional Cerros de Amotape en el noroeste peruano, inventariando seis parcelas de una hectárea cada una. Para ello se utilizó la versión modificada de la estadística K de Ripley. Eriotheca ruizii (K. Schum. A. Robyns (Bombacaceae, Bursera graveolens (Kunth Triana & Planch. (Burseraceae, Caesalpinia glabrata Kunth (Leguminosae y Cochlospermum vitifolium (Willd. Spreng. (Cochlospermaceae presentan patrones que no son significantemente diferentes de un patrón completamente al azar en 11 de los 17 casos analizados. Al nivel de la escala espacial analizada, esto está en desacuerdo con el postulado general para bosques tropicales de que las especies vegetales tienden a encontrarse agrupadas. Estos resultados se analizan y discuten a la luz de los diversos factores que influyen en producirlos.

Bosque das mangueiras: projeto paisagístico como ferramenta de reabilitação do entorno da reitoria da Universidade Federal do Piauí

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Caio Frederico E. Silva

2007-12-01

Full Text Available O projeto de reabilitação do “Bosque das Mangueiras” da Reitoria da Universidade Federal do Piauí - UFPI foi desenvolvido como experiência piloto do grupo de estudos do Laboratório Urbano da Paisagem - LUPA e apresenta diagnóstico e pressupostos teóricos para subsidiar intervenções paisagísticas nos espaços livres do campus universitário. Considerando a valorização das áreas verdes e a avaliação bioclimática, integrou-se a este trabalho o projeto de iniciação científica, em andamento, que caracteriza o perfil microclimático da cidade universitária identificando neste espaço livre bons condicionantes de conforto ambiental. A reabilitação do bosque agregará valores ao entorno, proporcionando experiências de contemplação, permanência e contribuindo na legibilidade da Reitoria, símbolo de representatividade.

Does deposition depth control the OSL bleaching of fluvial sediment?

NARCIS (Netherlands)

Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

2014-01-01

The Optically Stimulated Luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

Stability of Fluvial and Gravity-flow Antidunes

Science.gov (United States)

Fedele, J. J.; Hoyal, D. C. J. D.; Demko, T. M.

2017-12-01

Antidunes develop as a consequence of interface (free surface) deformation and sediment transport feedback in supercritical flows. Fluvial (open-channel flow) antidunes have been studied extensively in the laboratory and the field, and recognized in ancient sedimentary deposits. Experiments on gravity flow (turbidity and density currents) antidunes indicate that they are more stable and long-lived than their fluvial counterpart but the mechanism controlling this stability is poorly understood. Sea floor bathymetric and subsurface data suggest that large-scale, antidune-like sediment waves are extremely common in deep-water, found in a wide range of settings and sediment characteristics. While most of these large features have been interpreted as cyclic steps, the term has been most likely overused due to the lack of recognition criteria and basic understanding on the differences between antidunes and cyclic steps formed under gravity flows. In principle, cyclic steps should be more common in confined or channel-lobe transition settings where flows tend to be more energetic or focused, while antidunes should prevail in regions of less confinement, under sheet-like or expanding flows. Using published, fluvial stable-antidune data, we show that the simplified 1D, mechanical-energy based analysis of flow over a localized fixed obstacle (Long, 1954; Baines, 1995; Kubo and Yokokawa, 2001) is inaccurate for representing flow over antidunes and their stability. Instead, a more detailed analysis of a flow along a long-wavelength (in relation to flow thickness) wavy bed that also considers the interactions between flow and sediment transport is used to infer conditions of antidune stability and the breaking of surface waves. In particular, the position of the surface wave crest in relation to the bedform crest, along with the role of average flow velocity, surface velocity, and surface wave celerity appear relevant in determining antidune instability. The analysis is

Nove interpretacije fluvialnih sedimentov na krasu = New interpretations of fluvial sediments from the Kras

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Andrej Mihevc

2007-01-01

Full Text Available Important unroofed caves with fluvial sediments from Divaški kras, Matarsko podoljePodgorski kras are presented. Extend of the phenomena and relation to the existingand karst surface and geomorphological meaning of them are described. Sedimentsthem were analysed and dated with different methods. The largest age of the sedimentfound in the unroofed cave excavated in Črnotiče quarry. In the cave wall fossil remainsstygobiont Marifugia cavatica were covered by 3.2-4.1 Ma old fluvial sediments.

Nueva especie de zapote de monte (Phragmotheca, Bombacacea en bosques premontanos del centro de Colombia

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Fernández Alonso José Luis

1999-11-01

Full Text Available A new species of Phragmotheca (Bombacaceae is described and illustrated. This represents the first record of this genus in premontane forest (subandean belt and is also the first locality for Phragmotheca in the Eastern Cordillera of Colombia. The genus was previously known only from the Chocó biogeographic region and the Amazonian lowlands.Se describe e ilustra una nueva especie de Phragmotheca (Bombacaceae, que representa el primer registro del género en bosques premontanos (franja subandina y en la Cordillera Oriental de Colombia. Phragmotheca era conocido hasta ahora, sólo de la región biogeográfica chocoana y de la planicie amazónica.

La protección de los bosques naturales a la luz del Derecho Ambiental Internacional y la constitución brasileña: ¿Serán capaces de salvar la Floresta Amazónica?

OpenAIRE

Carvalho, Edson Ferreira

2016-01-01

Este estudio objetiva elucidar las relaciones normativas sobre bosques naturales dentro de los diversos campos del Derecho Ambiental Internacional y del ordenamiento jurídico brasileño y proponer soluciones para aumentar la efectividad del control de la deforestación. Dado el carácter teórico del estudio se utilizaron las técnicas de investigación documental y bibliográfica. Inicialmente, fueron analizados la relevancia de los bosques naturales para el planeta y la humanidad; el régimen juríd...

Precambrian fluvial deposits: Enigmatic palaeohydrological data from the c. 2 1.9 Ga Waterberg Group, South Africa

Science.gov (United States)

Eriksson, Patrick G.; Bumby, Adam J.; Brümer, Jacobus J.; van der Neut, Markus

2006-08-01

Precambrian fluvial systems, lacking the influence of rooted vegetation, probably were characterised by flashy surface runoff, low bank stability, broad channels with abundant bedload, and faster rates of channel migration; consequently, a braided fluvial style is generally accepted. Pre-vegetational braided river systems, active under highly variable palaeoclimatic conditions, may have been more widespread than are modern, ephemeral dry-land braided systems. Aeolian deflation of fine fluvial detritus does not appear to have been prevalent. With the onset of large cratons by the Neoarchaean-Palaeoproterozoic, very large, perennial braided river systems became typical. The c. 2.06-1.88 Ga Waterberg Group, preserved within a Main and a smaller Middelburg basin on the Kaapvaal craton, was deposited largely by alluvial/braided-fluvial and subordinate palaeo-desert environments, within fault-bounded, possibly pull-apart type depositories. Palaeohydrological data obtained from earlier work in the Middelburg basin (Wilgerivier Formation) are compared to such data derived from the correlated Blouberg Formation, situated along the NE margin of the Main basin. Within the preserved Blouberg depository, palaeohydrological parameters estimated from clast size and cross-bed set thickness data, exhibit rational changes in their values, either in a down-palaeocurrent direction, or from inferred basin margin to palaeo-basin centre. In both the Wilgerivier and Blouberg Formations, calculated palaeoslope values (derived from two separate formulae) plot within the gap separating typical alluvial fan gradients from those which characterise rivers (cf. [Blair, T.C., McPherson, J.G., 1994. Alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes, and facies assemblages. J. Sediment. Res. A64, 450-489.]). Although it may be argued that such data support possibly unique fluvial styles within the Precambrian, perhaps related to

Fluvial landscape development in the southwestern Kalahari during the Holocene - Chronology and provenance of fluvial deposits in the Molopo Canyon

DEFF Research Database (Denmark)

Ramisch, Arne; Bens, Oliver; Buylaert, Jan-Pieter

2017-01-01

are sparse and often discontinuous. Hence, little is known about Holocene environmental change in this region. This study focuses on reconstructing paleoenvironmental change from the timing and provenance of fluvial deposits located within the Molopo Canyon, which connects the southern Kalahari drainage...... to the deposition of alluvial fills. These results suggest that the southern Kalahari Drainage remained endorheic and therefore disconnected from the Orange River throughout the Holocene....

Diversidad de árboles y arbustos en fragmentos de bosque nativo en el sur de Chile

OpenAIRE

Pincheira-Ulbrich, J; Rau, JR; Hauenstein, E

2008-01-01

Se muestreó la diversidad de árboles y arbustos, y se construyó la curva de rarefacción y de acumulación de especies en 10 fragmentos de bosque nativo en el sur de Chile. Los resultados indicaron que: (1) la riqueza del conjunto de fragmentos fue igual a 23 especies, (2) la diversidad se incrementó significativamente con el tamaño de fragmento, (3) todos los fragmentos requieren un muestreo mínimo de entre 40 y 170 individuos para lograr la riqueza máxima teórica de especies, y (4) la riqueza...

Late Cenozoic fluvial successions in northern and western India: an overview and synthesis

Science.gov (United States)

Sinha, R.; Kumar, R.; Sinha, S.; Tandon, S. K.; Gibling, M. R.

2007-11-01

Late Cenozoic fluvial successions are widespread in India. They include the deposits of the Siwalik basin which represent the accumulations of the ancient river systems of the Himalayan foreland basin. Palaeomagnetic studies reveal that fluvial architecture and styles of deposition were controlled by Himalayan tectonics as well as by major climatic fluctuations during the long (∼13 Ma) span of formation. The Indo-Gangetic plains form the world's most extensive Quaternary alluvial plains, and display spatially variable controls on sedimentation: Himalayan tectonics in the frontal parts, climate in the middle reaches, and eustasy in the lower reaches close to the Ganga-Brahmaputra delta. Climatic effects were mediated by strong fluctuations in the SW Indian Monsoon, and Himalayan rivers occupy deep valleys in the western Ganga plains where stream power is high, cut in part during early Holocene monsoon intensification; the broad interfluves record the simultaneous aggradation of plains-fed rivers since ∼100 ka. The eastward increase in precipitation across the Ganga Plains results in rivers with low stream power and a very high sediment flux, resulting in an aggradational mode and little incision. The river deposits of semi-arid to arid western India form important archives of Quaternary climate change through their intercalation with the eolian deposits of the Thar Desert. Although the synthesis documents strong variability-both spatial and temporal-in fluvial stratigraphy, climatic events such as the decline in precipitation during the Last Glacial Maximum and monsoon intensification in the early Holocene have influenced fluvial dynamics throughout the region.

"The Waters of Meridiani" - Further Support for a Fluvial Interpretation of the Ridged, Layered Units

Science.gov (United States)

Wilkinson, Justin; Kreslavsky, Misha

2009-01-01

A relatively unknown terrestrial fluvial environment, the mesoscale megafan, provides analogs for various Martian landscapes, including the etched unit (etched unit, Unite E of Arvidson et al., 2003; ridge-forming unit R of Edgett, 2005) of the Sinus Meridiani region on Mars. A global survey of Earth shows that megafans are very large partial cones of dominantly fluvial sediment with radii on the order of hundreds of km, and very low slopes. Responsible fluvial processes are sufficiently different from those of classical arid alluvial fans and deltas that it is useful to class megafans as separate features. The megafan model calls into question two commonly held ideas. 1. Earth examples prove that topographic basins per se are unnecessary for the accumulation of large sedimentary bodies. 2. River channels are by no means restricted to valleys (Meridiani sediments are termed a "valley-ed volume" of Edgett). These perspectives reveal unexpected parallels with features at Meridiani-several channel-like features that are widespread, mostly as ridges inverted by eolian erosion; channel networks covering thousands of sq km, especially on intercrater plains; and regional relationships of sediment bodies situated immediately downstream of highland masses. These all suggest that fluvial explanations are at least part of the Meridiani story.

Beaver ponds' impact on fluvial processes (Beskid Niski Mts., SE Poland).

Science.gov (United States)

Giriat, Dorota; Gorczyca, Elżbieta; Sobucki, Mateusz

2016-02-15

Beaver (Castor sp.) can change the riverine environment through dam-building and other activities. The European beaver (Castor fiber) was extirpated in Poland by the nineteenth century, but populations are again present as a result of reintroductions that began in 1974. The goal of this paper is to assess the impact of beaver activity on montane fluvial system development by identifying and analysing changes in channel and valley morphology following expansion of beaver into a 7.5 km-long headwater reach of the upper Wisłoka River in southeast Poland. We document the distribution of beaver in the reach, the change in river profile, sedimentation type and storage in beaver ponds, and assess how beaver dams and ponds have altered channel and valley bottom morphology. The upper Wisłoka River fluvial system underwent a series of anthropogenic disturbances during the last few centuries. The rapid spread of C. fiber in the upper Wisłoka River valley was promoted by the valley's morphology, including a low-gradient channel and silty-sand deposits in the valley bottom. At the time of our survey (2011), beaver ponds occupied 17% of the length of the study reach channel. Two types of beaver dams were noted: in-channel dams and valley-wide dams. The primary effect of dams, investigated in an intensively studied 300-m long subreach (Radocyna Pond), was a change in the longitudinal profile from smooth to stepped, a local reduction of the water surface slope, and an increase in the variability of both the thalweg profile and surface water depths. We estimate the current rate of sedimentation in beaver ponds to be about 14 cm per year. A three-stage scheme of fluvial processes in the longitudinal and transverse profile of the river channel is proposed. C. fiber reintroduction may be considered as another important stage of the upper Wisłoka fluvial system development. Copyright © 2015 Elsevier B.V. All rights reserved.

Fluvial sediment inputs to upland gravel bed rivers draining forested catchments: potential ecological impacts

Directory of Open Access Journals (Sweden)

S. D. Marks

1997-01-01

Full Text Available As identified by the detailed long-term monitoring networks at Plynlimon, increased sediment supply to upland fluvial systems is often associated with forestry land-use and practice. Literature is reviewed, in the light of recent results from Plynlimon sediment studies, to enable identification of the potential ecological impacts of fluvial particulate inputs to upland gravel bed rivers draining forested catchments similar to the headwaters of the River Severn. Both sediment transport and deposition can have significant impacts upon aquatic vertebrates, invertebrates and plants.

Conservación de la biodiversidad y desarrollo humano en bosques montanos de Costa Rica

Directory of Open Access Journals (Sweden)

Juan Criado Hernández

2013-05-01

Full Text Available Costa Rica es el país que posee la mayor biodiversidad del planeta en relación con su extensión (en 51 100 km2 tiene aproximadamente el 5% de la biodiversidad mundial; esto, junto al compromiso político de integrar las políticas de desarrollo humano y de medio ambiente, han consolidado el país como líder en conservación en América Latina.  Lo anterior ha favorecido, además, el desarrollo del ecoturismo, el pago de servicios ambientales y la fijación de carbono, como alternativas para el aprovechamiento racional de los recursos naturales. A pesar de estos esfuerzos, es evidente la necesidad de promover investigaciones que ayuden a entender las interacciones entre naturaleza y sociedad, base del desarrollo sostenible. A escala internacional, los Objetivos de Desarrollo del Milenio (2005, el reciente Congreso de Áreas Protegidas en Mesoamérica (Panamá, 2006 y el último Congreso de la Asociación de Biología Tropical y Conservación (México, 2007, son algunos ejemplos que destacan esta misma necesidad. Se presenta una aproximación interdisciplinar para determinar las relaciones que existen entre la biodiversidad y el bienestar humano en bosques montanos de Costa Rica. La hipótesis considera que un buen estado de conservación del bosque tiene una correlación positiva con un acceso equitativo a las condiciones necesarias para mejorar el bienestar humano de las comunidades. Para esto, se desarrolla una metodología sencilla basada en un conjunto de indicadores biológicos y sociales. En los indicadores biológicos se considera la estructura del bosque y su relación con especies de aves frugívoras como indicadores funcionales de biodiversidad, debido a su papel como dispersores de semillas en las montañas del trópico. Los indicadores sociales están basados en la participación social, por la función que cumple en la distribución de los beneficios generados por el medio ambiente. Para ello se analizan las redes de participaci

Dose response of artificial irradiation of fluvial sediment sample for ESR dating

International Nuclear Information System (INIS)

Liu Chunru; Yin Gongming; Gao Lu; Li Jianping; Han Fei; Lin Min

2011-01-01

ESR dating samples need be irradiated to obtain dose response curve and the equivalent dose. The artificial dose rate is about 1 x 10 -1 -1 x 10 2 Gy/min, whereas the natural dose rate is about 3 Gy/ka. Therefore, one must be sure whether the much higher artificial dose rate is suitable for the ESR dating study. In this paper, we use different artificial dose rate to irradiate the same fluvial sample and measure the quartz Al centre ESR signal under the same conditions. The dose response curves are compared, in an attempt to gain a preliminary knowledge on that problem and build a good foundation for our ESR dating studies on fluvial samples. (authors)

Hydrodynamic and sedimentological controls governing formation of fluvial levees

Science.gov (United States)

Johnston, G. H.; Edmonds, D. A.; David, S. R.; Czuba, J. A.

2017-12-01

Fluvial levees are familiar features found on the margins of river channels, yet we know little about what controls their presence, height, and shape. These attributes of levees are important because they control sediment transfer from channel to floodplain and flooding patterns along a river system. Despite the familiarity and importance of levees, there is a surprising lack of basic geomorphic data on fluvial levees. Because of this we seek to understand: 1) where along rivers do levees tend to occur?; 2) what geomorphic and hydrodynamic variables control cross-sectional shape of levees? We address these questions by extracting levee shape from LiDAR data and by collecting hydrodynamic and sedimentological data from reaches of the Tippecanoe River, the White River, and the Muscatatuck River, Indiana, USA. Fluvial levees are extracted from a 1.5-m resolution LiDAR bare surface model and compared to hydrological, sedimentological, and geomorphological data from USGS stream gages. We digitized banklines and extracted levee cross-sections to calculate levee slope, taper, height, e-folding length, and e-folding width. To answer the research questions, we performed a multivariable regression between the independent variables—channel geometry, sediment grain size and concentration, flooding conditions, and slope—and the dependent levee variables. We find considerable variation in levee presence and shape in our field data. On the Muscatatuck River levees occur on 30% of the banks compared to 10% on the White River. Moreover, levees on the Muscatatuck are on average 3 times wider than the White River. This is consistent with the observation that the Muscatatuck is finer-grained compared to the White River and points to sedimentology being an important control on levee geomorphology. Future work includes building a morphodynamic model to understand how different hydrodynamic and geomorphic conditions control levee geometry.

IDENTIFICACIÓN DE HONGOS ANTAGONISTAS A Phytophthora cinnamomi Rands EN BOSQUES DE ENCINO DE EL ARRAYANAL, COLIMA Y TECOANAPA, GUERRERO

Directory of Open Access Journals (Sweden)

Alejandra Almaraz-Sánchez

2012-01-01

Full Text Available El objetivo del presente estudio fue identificar morfológica y molecularmente la micoflora que posee propiedades antagonistas sobre Phytophthora cinnamomi, asociada al suelo del bosque de encino (Quercus spp. de El Arrayanal, Colima, y de Tecoanapa, Guerrero. En estas localidades se realizaron dos muestreos de suelo colectándose muestras compuestas de suelo-raíz alrededor de los árboles con diferentes edades y condiciones sanitarias en rodales afectados por P. cinnamomi. Los hongos se identificaron morfológicamente mediante la técnica de dilución de suelo PDA-TS (papa-dextrosaagar-tergitol-estreztomicina. Con los aislamientos obtenidos se realizaron pruebas de antagonismo in vitro. Los aislamientos de Trichoderma, Cordyceps bassiana y Paecilomyces son los que ejercieron mejor biocontrol al reducir el desarrollo de P. cinnamomi mostrando mecanismos sobresalientes de competencia por espacio y micoparasitismo. Los hongos se caracterizaron molecularmente amplificando la región intergénica (ITS de los genes ribosomales mediante la técnica de amplificación por reacción en cadena de la polimerasa (PCR. Se reportan por vez primera a C. bassiana, Cladosporium tenuissimun y seis especies de Trichoderma asociadas al bosque de encino en México.

Two depositional models for Pliocene coastal plain fluvial systems, Goliad Formation, south Texas Gulf Coastal plain

International Nuclear Information System (INIS)

Hoel, H.D.; Galloway, W.E.

1983-01-01

The Goliad Formation consists of four depositional systems-the Realitos and Mathis bed-load fluvial systems in the southwest and the Cuero and Eagle Lake mixed-load fluvial systems in the northeast. Five facies are recognized in the Realitos and Mathis bed-load fluvial systems: (1) primary channel-fill facies, (2) chaotic flood channel-fill facies, (3) complex splay facies, (4) flood plain facies, and (5) playa facies. A model for Realitos-Mathis depositional environments shows arid-climate braided stream complexes with extremely coarse sediment load, highly variable discharge, and marked channel instability. Broad, shallow, straight to slightly sinuous primary channels were flanked by wide flood channels. Flood channels passed laterally into broad, low-relief flood plains. Small playas occupied topographic lows near large channel axes. Three facies are recognized in the Cuero and Eagle Lake mixed-load fluvial systems: (1) channel-fill facies, (2) crevasse splay facies, and (3) flood plain facies. A model for Cuero-Eagle Lake depositional environments shows coarse-grained meander belts in a semi-arid climate. Slightly to moderately sinuous meandering streams were flanked by low, poorly developed natural levees. Crevasse splays were common, but tended to be broad and ill-defined. Extensive, low-relief flood plains occupied interaxial areas. The model proposed for the Realitos and Mathis fluvial systems may aid in recognition of analogous ancient depositional systems. In addition, since facies characteristics exercise broad controls on Goliad uranium mineralization, the proposed depositional models aid in defining target zones for Goliad uranium exploration

Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

Relación del gradiente interior-borde de fragmentos de bosque andino sobre la comunidad de murciélagos en Encino (Santander, Colombia

Directory of Open Access Journals (Sweden)

Aída Otálora Ardila

2005-01-01

área total y tienen una densidad de 0,39 parches/ha. Los índices calculados revelan que los bosques andinos tienen un menor proceso de fragmentación que los subandinos representado en fragmentos más grandes y más cercanos. El paisaje ha sido muy transformado pues el 90,4% de los fragmentos son

Reconstructing paleo-discharge from geometries of fluvial sinuous ridges on Earth and Mars

Science.gov (United States)

Hayden, A.; Lamb, M. P.; Mohrig, D. C.; Williams, R. M. E.; Myrow, P.; Ewing, R. C.; Cardenas, B. T.; Findlay, C. P., III

2017-12-01

Sinuous, branching networks of topographic ridges resembling river networks are common across Mars, and show promise for quantifying ancient martian surface hydrology. There are two leading formation mechanisms for ridges with a fluvial origin. Inverted channels are ridges that represent casts (e.g., due to lava fill) of relict river channel topography, whereas exhumed channel deposits are eroded remnants of a more extensive fluvial deposit, such as a channel belt. The inverted channel model is often assumed on Mars; however, we currently lack the ability to distinguish these ridge formation mechanisms, motivating the need for Earth-analog study. To address this issue, we studied the extensive networks of sinuous ridges in the Ebro basin of northeast Spain. The Ebro ridges stand 3-15 meters above the surrounding plains and are capped by a cliff-forming sandstone unit 3-10 meters thick and 20-50 meters in breadth. The caprock sandstone bodies contain bar-scale cross stratification, point-bar deposits, levee deposits, and lenses of mudstone, indicating that these are channel-belt deposits, rather than casts of channels formed from lateral channel migration, avulsion and reoccupation. In plan view, ridges form segments branching outward to the north resembling a distributary network; however, crosscutting relationships indicate that ridges cross at different stratigraphic levels. Thus, the apparent network in planview reflects non-uniform exhumation of channel-belt deposits from multiple stratigraphic positions, rather than an inverted coeval river network. As compared to the inverted channel model, exhumed fluvial deposits indicate persistent fluvial activity over geologic timescales, indicating the potential for long-lived surface water on ancient Mars.

Anguilles estuariennes et fluviales : apports de l'otolithométrie

Directory of Open Access Journals (Sweden)

MOUNAIX B.

1994-10-01

La zonation de l'otolithe, interprétée par rapport à la croissance des poissons, décrit deux écotypes dans la population d'anguilles de la Vilaine : un écotype fluvial dont la croissance est perturbée et ralentie, et un écotype estuarien dont la croissance est plus régulière. Cette partition de la population est cohérente avec les caractéristiques environnementales des deux milieux. Elle pourrait par ailleurs constituer un indice de l'impact des aménagements des bassins versants sur la croissance, la durée du cycle biologique et la dynamique des populations d'anguilles. Il apparaît alors nécessaire de considérer séparément les sous-unités estuariennes et fluviales des stocks d'anguilles des bassins versants de la Vilaine et de la Loire, en particulier pour étudier la diminution des abondances.

Conocimiento y valoración de la calidad ambiental de la Reserva Forestal Bosque de Yotoco: perspectiva psicoambiental

Directory of Open Access Journals (Sweden)

Henry Granada

2015-01-01

Full Text Available El presente trabajo de investigación se enmarca en el campo de la Psicología Ambiental y tuvo como propósito describir los conocimientos y las valoraciones que las personas expresaron sobre la calidad ambiental de la Reserva Forestal Bosque de Yotoco (Valle del Cauca, Colombia, así como descubrir sugerencias implícitas o explicitas pertinentes para el mejoramiento de la calidad ambiental del ecosistema en mención. Los participantes fueron algunos de los visitantes a la reserva desde el año 1994 hasta el 2011. Este estudio utilizó una estrategia metodológica cualitativa. Los datos analizados se obtuvieron a través del muestreo al azar de los libros de registro de visitantes, en el cual éstos escriben los comentarios sobre el carácter de su experiencia inmediatamente culminan el recorrido de la misma. Los resultados son ampliamente favorables hacia el reconocimiento de la calidad ambiental de la Reserva en sus aspectos físicos, bióticos y especialmente los psicosociales. Se destacan algunos comentarios relacionados con la apreciación del paisaje, la importancia como fuente originaria y reguladora de agua, el ser uno de los pocos “sobrevivientes” de bosque en la vertiente oriental de la cordillera occidental colombiana, la buena atención de los funcionarios y su posibilidad para la educación ambiental pertinente.

Moluscos gasterópodos terrestres como indicadores de recuperación de bosque en los paisajes del Sur y Norcentro de Nicaragua

Directory of Open Access Journals (Sweden)

Marlon Sotelo

2015-10-01

Full Text Available Los moluscos terrestres son un grupo altamente diverso cuyo trabajo investigativo en Nicaragua ha sido mayoritariamente en la vertiente del Pacífico de Nicaragua. Evaluar el potencial de estas especies como indicadores de la perdida de la masa boscosa así como de su recuperación ayudará el impacto de las actividades humanas en esta biota de escasa movilidad. La colectas de conchas y especímenes fué realizada en bosques húmedos, nubosos y secos en los departamentos de Rivas y Jinotega en hábitats específicos dentro de la matrix del paisaje. Las identificaciones a posteriori fueron hechas para evitar el sesgo de identificaciones en especies de taxonomía debatible. Los hábitats forestales continuos mostraron valores mayores en biodiversidad que otros hábitats dentro de la matrix, mostrando que existe fidelidad de hábitat para la comunidad de caracoles en general. Esta alta fidelidad, muestra la importancia de este grupo cuando tratamos de obtener especies de fidelidad alta, ayudando a explicar cómo la perdida de bosque afecta a la fauna.

Impactos, vulnerabilidad y adaptación al Cambio Climático en los bosques ibéricos.

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Asier Herrero

2017-01-01

Full Text Available Se han registrado numerosos impactos relacionados con el cambio climático en los bosques ibéricos que pueden cambiar la composición, estructura y funcionamiento de los mismos. Es importante considerar que los efectos del cambio climático interactúan comúnmente con otros motores de cambio, dificultando de esta manera la cuantificación de la contribución del cambio climático en los impactos observados. Entre los impactos registrados encontramos alteraciones fisiológicas, fenológicas, demográficas y de distribución, las cuales a su vez pueden provocar cambios en la composición, estructura y funcionamiento de los ecosistemas forestales ibéricos. A medida que el cambio climático avance, y las condiciones climáticas se alejen cada vez más de las actuales, se espera un aumento de los impactos observados. En este contexto, se hace necesario evaluar correctamente la vulnerabilidad de poblaciones, especies y ecosistemas frente al cambio climático futuro para poder diseñar y aplicar medidas de adaptación eficaces que minimicen los impactos y favorezcan el proceso de ajuste a las nuevas condiciones. La aplicación de las medidas de adaptación debe enmarcarse en una gestión adaptativa y anticipadora, que fomente la colaboración activa entre todos los actores involucrados en la gestión e investigación de los bosques ibéricos.

Late Holocene lowland fluvial archives and geoarchaeology : Utrecht's case study of Rhine river abandonment under Roman and Medieval settlement

NARCIS (Netherlands)

van Dinter, M.; Cohen, K.M.; Hoek, W.Z.; Stouthamer, E.; Jansma, E.; Middelkoop, H.

2017-01-01

Fluvial lowlands have become attractive human settling areas all around the world over the last few millennia. Because rivers kept changing their course and networks due to avulsion, the sedimentary sequences in these areas are archives of both fluvial geomorphological and archaeological

Pre- and post-remediation characterization of acid-generating fluvial tailings material

Science.gov (United States)

Smith, Kathleen S.; Walton-Day, Katherine; Hoal, Karin O.; Driscoll, Rhonda L.; Pietersen, K.

2012-01-01

The upper Arkansas River south of Leadville, Colorado, USA, contains deposits of fluvial tailings from historical mining operations in the Leadville area. These deposits are potential non-point sources of acid and metal contamination to surface- and groundwater systems. We are investigating a site that recently underwent in situ remediation treatment with lime, fertilizer, and compost. Pre- and post-remediation fluvial tailings material was collected from a variety of depths to examine changes in mineralogy, acid generation, and extractable nutrients. Results indicate sufficient nutrient availability in the post-remediation near-surface material, but pyrite and acid generation persist below the depth of lime and fertilizer addition. Mineralogical characterization performed using semi-quantitative X-ray diffraction and quantitative SEM-based micro-mineralogy (Mineral Liberation Analysis, MLA) reveal formation of gypsum, jarosite, and complex coatings surrounding mineral grains in post-remediation samples.

Reabsorción de nitrógeno y fósforo foliar en árboles de bosques montanos en los Andes centrales de Colombia

Directory of Open Access Journals (Sweden)

Miguel Vera

1999-06-01

Full Text Available Se determinaron las concentraciones y los porcentajes de reabsorción de nitrógeno y fósforo foliar en cinco especies de árboles de un bosque montano bajo (BMB a 1850 m.s.n.m. y en cinco de un bosque montano alto (BMA a 2800 m.s.n.m en la Cordillera Central colombiana, asi como la disponibilidad de nitrógeno y fósforo del suelo. Los porcentajes de reabsorción de N y P no fueron significativamente diferentes entre las especies de estos dos bosques. A pesar de esto, se observó que la reabsorción de P foliar tendió a ser mayor en las especies del BMB donde la concentración de P en el suelo fue significativamente más baja (3.2 ppm vs. 9.0 ppm. Cuando la reabsorción de P foliar se expresó como función de la concentración en hojas maduras en 12 tipos de bosques montanos tropicales, se encontró una correlación negativa y estadísticamente significativa. Estos resultados sugieren que los porcentajes de reabsorción de P foliar en bosques montanos estarían controlados parcialmente por la disponibilidad del elemento.Mature leaves and litterfall were collected between November 1992 and February 1993 from one to three individuals of five canopy tree species of a lower montane rain forest (LMRF at 1850 m. and five canopy tree species of an upper montane rain forest (UMRF at 2800 m. in the Central Andes of Colombia, to determine the concentrations and percentage retranslocation of nitrogen and phosphorus. The availability of these two nutrients was measured in the soils, by means of extracts of NH3-NH4, NO2-NO3 and PO4, and incubations of surface soil samples (0-10 cm to measure the rates of nitrogen mineralization and nitrification. In the species of the LMRF the average concentration of N in mature leaves (1.19 % dry weight and litterfall (0.87 % was significantly higher than in mature leaves (0.90 % and litterfall (0.59 % of the tree species of the UMRF. Percentage retranslocation of N and P were not significantly different between the

Introduction to the special issue on discontinuity of fluvial systems

Science.gov (United States)

Burchsted, Denise; Daniels, Melinda; Wohl, Ellen E.

2014-01-01

Fluvial systems include natural and human-created barriers that modify local base level; as such, these discontinuities alter the longitudinal flux of water and sediment by storing, releasing, or changing the flow path of those materials. Even in the absence of distinct barriers, fluvial systems are typically discontinuous and patchy. The size of fluvial discontinuities ranges across scales from 100 m, such as riffles, to 104 m, such as lava dams or major landslides. The frequency of occurrence appears to be inversely related to size, with creation and failure of the small features, such as beaver dams, occurring on a time scale of 100 to 101 years and a frequency of occurrence at scales as low as 101 m. In contrast, larger scale discontinuities, such as lava dams, can last for time scales up to 105 years and have a frequency of occurrence of approximately 104 m. The heterogeneity generated by features is an essential part of river networks and should be considered as part of river management. Therefore, we suggest that "natural" dams are a useful analog for human dams when evaluating options for river restoration. This collection of papers on the studies of natural dams includes bedrock barriers, log jams and beaver dams. The collection also addresses the discontinuity generated by a floodplain — in the absence of an obvious barrier in the channel — and tools for evaluation of riverbed heterogeneity. It is completed with a study of impact of human dams on floodplain sedimentation. These papers will help geomorphologists and river managers understand the factors that control river heterogeneity across scales and around the world.

A laser profilometry technique for monitoring fluvial dike breaching in laboratory experiments

Science.gov (United States)

Dewals, Benjamin; Rifai, Ismail; Erpicum, Sébastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El kadi Abderrezzak, Kamal

2017-04-01

A challenging aspect for experimental modelling of fluvial dike breaching is the continuous monitoring of the transient breach geometry. In dam breaching cases induced by flow overtopping over the whole breach crest (plane erosion), a side view through a glass wall is sufficient to monitor the breach formation. This approach can be extended for 3D dam breach tests (spatial erosion) if the glass wall is located along the breach centreline. In contrast, using a side view does not apply for monitoring fluvial dike breaching, because the breach is not symmetric in this case. We present a non-intrusive, high resolution technique to record the breach development in experimental models of fluvial dikes by means of a laser profilometry (Rifai et al. 2016). Most methods used for monitoring dam and dike breaching involve the projection of a pattern (fringes, grid) on the dam or dike body and the analysis of its deformation on images recorded during the breaching (e.g., Pickert et al. 2011, Frank and Hager 2014). A major limitation of these methods stems from reflection on the water surface, particularly in the vicinity of the breach where the free surface is irregular and rippled. This issue was addressed by Spinewine et al. (2004), who used a single laser sheet so that reflections on the water surface were strongly limited and did not hamper the accurate processing of each image. We have developed a similar laser profilometry technique tailored for laboratory experiments on fluvial dike breaching. The setup is simple and relatively low cost. It consists of a digital video camera (resolution of 1920 × 1080 pixels at 60 frames per second) and a swiping red diode 30 mW laser that enables the projection of a laser sheet over the dike body. The 2D image coordinates of each deformed laser profile incident on the dike are transformed into 3D object coordinates using the Direct Linear Transformation (DLT) algorithm. All 3D object coordinates computed over a swiping cycle of the

Examining fluvial fish range loss with SDMs

Science.gov (United States)

Taylor, Andrew T.; Papeş, Monica; Long, James M.

2018-01-01

Fluvial fishes face increased imperilment from anthropogenic activities, but the specific factors contributing most to range declines are often poorly understood. For example, the range of the fluvial‐specialist shoal bass (Micropterus cataractae) continues to decrease, yet how perceived threats have contributed to range loss is largely unknown. We used species distribution models to determine which factors contributed most to shoal bass range loss. We estimated a potential distribution based on natural abiotic factors and a series of currently occupied distributions that incorporated variables characterizing land cover, non‐native species, and river fragmentation intensity (no fragmentation, dams only, and dams and large impoundments). We allowed interspecific relationships between non‐native congeners and shoal bass to vary across fragmentation intensities. Results from the potential distribution model estimated shoal bass presence throughout much of their native basin, whereas models of currently occupied distribution showed that range loss increased as fragmentation intensified. Response curves from models of currently occupied distribution indicated a potential interaction between fragmentation intensity and the relationship between shoal bass and non‐native congeners, wherein non‐natives may be favored at the highest fragmentation intensity. Response curves also suggested that >100 km of interconnected, free‐flowing stream fragments were necessary to support shoal bass presence. Model evaluation, including an independent validation, suggested that models had favorable predictive and discriminative abilities. Similar approaches that use readily available, diverse, geospatial data sets may deliver insights into the biology and conservation needs of other fluvial species facing similar threats.

Deciphering Fluvial-Capture-Induced Erosional Patterns at the Continental Scale on the Iberian Peninsula

Science.gov (United States)

Anton, L.; Munoz Martin, A.; De Vicente, G.; Finnegan, N. J.

2017-12-01

The process of river incision into bedrock dictates the landscape response to changes in climate and bedrock uplift in most unglaciated settings. Hence, understanding processes of river incision into bedrock and their topographic signatures are a basic goal of geomorphology. Formerly closed drainage basins provide an exceptional setting for the quantification of long term fluvial dissection and landscape change, making them valuable natural laboratories. Internally drained basins are peculiar because they trap all the sediment eroded within the watershed; as closed systems they do not respond to the base level of the global ocean and deposition is the dominant process. In that context, the opening of an outward drainage involves a sudden lowering of the base level, which is transmitted upstream along fluvial channels in the form of erosional waves, leading to high incision and denudation rates within the intrabasinal areas. Through digital topographic analysis and paleolandscape reconstruction based on relict deposits and landscapes on the Iberian Peninsula, we quantify the volume of sediments eroded from formerly internally drained basins since capture. Mapping of fluvial dissection patterns reveals how, and how far, regional waves of incision have propagated upstream. In our analysis, erosional patterns are consistent with the progressive establishment of an outward drainage system, providing a relative capture chronology for the different studied basins. Divide migration inferred from chi maps supports the interpretations based on fluvial dissection patterns and volumes, providing clues on how landscaped changed and how drainage integration occurred within the studied watersheds. [Funded by S2013/MAE-2739 and CGL2014-59516].

Efectos de plantaciones abandonadas de especies exóticas y nativas sobre la regeneración natural de un bosque montano en Colombia

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Jaime Cavelier

1999-12-01

Full Text Available Se realizaron censos de vegetación durante 1994 en una parcela de 0.1 ha. en cada una de las plantaciones abandonadas de Pinus radiata, Cupressus lusitanica, Eucalyptus globulus, Alnus acuminata y en un bosque secundario montano alto en los Andes centrales de Colombia. También fueron recolectados datos de las propiedades físicas y químicas de suelos superficiales. El bosque de regeneración natural tiene el mayor número de especies (33 seguido por las plantaciones de E. globulus (26 y A. acuminata (16. Las plantaciones abandonadas de P. radiata y C. lusitanica, tuvieron sólo tres especies. Entre el bosque de regeneración natural y la plantación de E. globulus hubo solamente once especies en común y solamente siete con la plantación de A. acuminata. Todas estas especies, con excepción de tres, son arbustos del sotobosque dispersados por viento o aves. En el sotobosque de la plantación de P. radiata había una regeneración abundante del árbol nacional de Colombia, Ceroxylum quindiuensis. La altura de los árboles y el área basal fueron significativamente mayores en las plantaciones de P. radiata y C. lusitanica que en el bosque de regeneración natural. De las variables ambientales y biológicas medidas en este estudio, la acumulación de acículas bajo las plantaciones de P. radiata y C. lusitanica y la alta biomasa de raíces finas bajo la plantación de C. lusitanica, podrían ser los principales factores limitantes para el establecimiento de un número mayor de especies del bosque nativo. Las propiedades químicas de los suelos varían ampliamente y no hubo diferencias coherentes entre los suelos bajo especies exóticas y nativas.Vegetation surveys were carried out during 1994 in 0.1. ha plots in abandoned plantations of Pinus radiata, Cupressus lusitanica, Eucalyptus globulus, Alnus acuminata and in a secondary upper montane rain forest in the Central Andes of Colombia. The regeneration forest had the higher number of plant

Heterogeneity in a Suburban River Network: Understanding the Impact of Fluvial Wetlands on Dissolved Oxygen and Metabolism in Headwater Streams

Science.gov (United States)

Cain, J. S.; Wollheim, W. M.; Sheehan, K.; Lightbody, A.

2014-12-01

Low dissolved oxygen content in rivers threatens fish populations, aquatic organisms, and the health of entire ecosystems. River systems with high fluvial wetland abundance and organic matter, may result in high metabolism that in conjunction with low re-aeration rates, lead to low oxygen conditions. Increasing abundance of beaver ponds in many areas may exacerbate this phenomenon. This research aims to understand the impact of fluvial wetlands, including beaver ponds, on dissolved oxygen (D.O.) and metabolism throughout the headwaters of the Ipswich R. watershed, MA, USA. In several fluvial wetland dominated systems, we measured diel D.O. and metabolism in the upstream inflow, the surface water transient storage zones of fluvial wetland sidepools, and at the outflow to understand how the wetlands modify dissolved oxygen. D.O. was also measured longitudinally along entire surface water flow paths (x-y km long) to determine how low levels of D.O. propagate downstream. Nutrient samples were also collected to understand how their behavior was related to D.O. behavior. Results show that D.O. in fluvial wetlands has large swings with periods of very low D.O. at night. D.O. swings were also seen in downstream outflow, though lagged and somewhat attenuated. Flow conditions affect the level of inundation and the subsequent effects of fluvial wetlands on main channel D.O.. Understanding the D.O. behavior throughout river systems has important implications for the ability of river systems to remove anthropogenic nitrogen.

Experimental insights into organic carbon oxidation potential during fluvial transport without floodplain storage

Science.gov (United States)

Scheingross, J. S.; Hovius, N.; Sachse, D.; Vieth-Hillebrand, A.; Turowski, J. M.; Hilton, R. G.

2016-12-01

Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, rock, and biosphere is thought to be a major control on global climate. CO2 flux estimates from oxidation of rock-derived OC and sequestration of biospheric OC during fluvial transit from source to sink are approximately the same order of magnitude or larger than those from silicate weathering. Despite field data showing loss of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in laboratory experiments simulating fluvial transport without floodplain storage. Mixtures of OC-rich and siliciclastic sediment were transported for distances of 2000 km in annular flumes while making time-series measurements of sediment TOC and water DOC concentrations. Initial results for transport of OC-rich soil show increasing DOC with transport distance to levels that represent a transfer of 2% of the total OC from the solid to the dissolved phase; however, we observed no detectable change in the solid-phase TOC. Similar results were obtained in a control experiment with identical sediment in still water. These preliminary results suggest minimal OC oxidation within our experiment, and, to the extent that such experiments represent natural transport through river systems, are consistent with the hypothesis that OC losses may occur primarily during floodplain storage rather than fluvial transport.

Los trabajadores subcontratistas de Bosques Arauco y CODELCO: ¿Un movimiento en vías de politización?

OpenAIRE

Claudia Jordana Contreras; Juana Torres Cierpe

2009-01-01

Uno de los principales problemas que atraviesa la sociedad actual es la despolitización. Los movimientos de los trabajadores subcontratistas de CODELCO y Bosques Arauco, sin embargo, parecen oponerse a esa tendencia. En esta investigación se estudia, precisamente, si eso es así, es decir, si estos movimientos son susceptibles de ser analizados desde un punto de vista político; si tienen posibilidades de proyectarse en el tiempo o si sus demandas y reivindicaciones son más bien coyunturales. L...

DIVERSIDAD DE MARIPOSAS DIURNAS (HESPERIOIDEA-PAPILIONOIDEA EN TRES ESTADOS SUCESIONALES DE UN BOSQUE HUMEDO PREMONTANO BAJO, TULUÁ, VALLE DEL CAUCA

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FABIÁN G. GAVIRIA-ORTIZ

2014-07-01

Full Text Available El efecto de la transformación de tierras para el cultivo y pastoreo hace que se genere un mosaico de hábitats provocando un proceso de sucesión vegetal y  afectando los organismos presentes en los distintos remanentes. El objetivo de este trabajo es comparar la diversidad de mariposas diurnas (Hesperoidea-Papilionoidea  en tres estados sucesionales (ES (Bosque secundario de 40 años (Bs-40, Bosque secundario de 20 años (Bs-20 y Rastrojo alto (Ra-A. Se calcularon índices de diversidad y posteriormente se utilizó un Kruskal-Wallis para determinar diferencias entre los componentes de diversidad en cada ES. Se obtuvieron un total de 305 especies (2572 registros. El mayor número de especies se obtuvo en el Bs-40 seguido del Ra-A y Bs-20. El índice de diversidad de Shannon-weaner (H demostró que la familia Nymphalidae aumento su valor según el grado de sucesión vegetal a diferencias del resto de familias. No se encontraron diferencias para la riqueza registrada con red entomológica y en la abundancia para los ES, pero si con las trampas. Los ES aportan gran diversidad de mariposas a pesar de los diferentes grados de intervención

Revisión de índices de distribución espacial usados en inventarios forestales y su aplicación en bosques tropicales

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Alicia Ledo

2012-10-01

Full Text Available En este trabajo se hace una revisión de los diferentes índices utilizados para describir y caracterizar la estructura horizontal o patrón espacial en masas forestales con especial énfasis en aquellos que se han aplicado para el estudio de bosques tropicales. Estos índices se han clasificado en función del tipo de datos requerido para su cálculo. Diferentes aspectos del comportamiento estadístico y la aplicabilidad de aquellos índices más usados (los índices de Fisher y Morisita, el análisis de la varianza en escalas anidadas y la técnica SADIE de entre las técnicas que utilizan datos de densidades o coberturas en unidades de muestreo; los índices de Clark-Evans, Pielou y Byth-Ripley basados en medidas de distancias entre árboles; y las funciones L(d y Oring que requieren para su cálculo la posición de todos los arboles se analizan en un caso de estudio a partir de datos de parcelas experimentales un bosque tropical andino.

Equation for estimating tree biomass in tropical forests of Costa Rica Ecuación para estimar la biomasa arbórea en los bosques tropicales de Costa Rica

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Shu Wei-Chou

2013-06-01

methodological approach to estimate forest biomass, which is very useful to support decision-making on carbon storage in tropical forests. Biomass determination in the field in future plots is going to help the calibration of this approach to estimate biomass stored in tropical forests.Una de las medidas más relevantes para la mitigación del cambio climático es la conservación y regeneración del bosque en nuestros países.  La cantidad de carbono que se almacena en la biomasa arbórea pasa a ser una medida relevante para la política pública. El presente trabajo analiza la asociación que tienen algunas variables dasométricas, fácilmente medibles, asociadas a la biomasa, con el propósito de estimarla indirectamente, dado que la medición directa de la biomasa arbórea es un trabajo complejo y tiene un costo muy elevado.  El objetivo general del estudio fue hacer un análisis del comportamiento de las variables dasométricas fácilmente medibles para predecir biomasa arbórea con datos de dos bosques tropicales de Costa Rica, con el propósito de analizar su posible aplicación generalizada en los bosques tropicales de todo el país. Mediante una revisión bibliográfica, se determinaron cuatro posibles modelos que estiman biomasa en bosques tropicales. Se evaluaron 907 árboles con diámetro a la altura de pecho (dap mayor a 10 cm en dos bosques tropicales de Costa Rica (Parque Nacional Corcovado en el suroeste y Fila Carbón en el sureste, vertiente del Caribe, generando una estimación de biomasa lo más precisa posible. Se realizó un análisis de las variables de los árboles (densidad específica de la madera, altura total y dap y su biomasa, con el fin de desarrollar el modelo que facilitara la predicción de esta. El modelo final utiliza como variables independientes el dap y la densidad.  Con el dap se da el hecho de que existe una alta correlación con la altura total, la cual es muy difícil de obtener en el campo, de modo que se decidió no utilizarla. La

Utilization of ancient permafrost carbon in headwaters of Arctic fluvial networks

NARCIS (Netherlands)

Mann, Paul J.; Eglinton, Timothy I.; McIntyre, Cameron P.; Zimov, Nikita; Davydova, Anna; Vonk, Jorien E.; Holmes, Robert M.; Spencer, Robert G M

2015-01-01

Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. Arctic warming is promoting terrestrial permafrost thaw and shifting hydrologic flowpaths, leading to fluvial mobilization of ancient carbon stores. Here we describe 14 C and 13 C

When do plants modify fluvial processes? Plant-hydraulic interactions under variable flow and sediment supply rates

Science.gov (United States)

Manners, Rebecca B.; Wilcox, Andrew C.; Kui, Li; Lightbody, Anne F.; Stella, John C.; Sklar, Leonard S.

2015-02-01

Flow and sediment regimes shape alluvial river channels; yet the influence of these abiotic drivers can be strongly mediated by biotic factors such as the size and density of riparian vegetation. We present results from an experiment designed to identify when plants control fluvial processes and to investigate the sensitivity of fluvial processes to changes in plant characteristics versus changes in flow rate or sediment supply. Live seedlings of two species with distinct morphologies, tamarisk (Tamarix spp.) and cottonwood (Populus fremontii), were placed in different configurations in a mobile sand-bed flume. We measured the hydraulic and sediment flux responses of the channel at different flow rates and sediment supply conditions representing equilibrium (sediment supply = transport rate) and deficit (sediment supply plant species and configuration. Species-specific traits controlled the hydraulic response: compared to cottonwood, which has a more tree-like morphology, the shrubby morphology of tamarisk resulted in less pronation and greater reductions in near-bed velocities, Reynolds stress, and sediment flux rates. Under sediment-deficit conditions, on the other hand, abiotic factors dampened the effect of variations in plant characteristics on the hydraulic response. We identified scenarios for which the highest stem-density patch, independent of abiotic factors, dominated the fluvial response. These results provide insight into how and when plants influence fluvial processes in natural systems.

Fluvial organic carbon losses from oil palm plantations on tropical peat, Sarawak, Southeast Asia

Science.gov (United States)

Cook, Sarah; Page, Susan; Evans, Chris; Whelan, Mick; Gauci, Vincent; Lip Khoon, Kho

2017-04-01

Tropical peatlands are valuable stores of carbon. However, tropical peat swamp forests (TPSFs) in Southeast Asia have increasingly been converted to other land-uses. For example, more than 25% of TPSFs are now under oil palm plantations. This conversion - requiring felling and burning of trees and drainage of the peat - can enhance carbon mineralization, dissolved organic carbon (DOC) losses and can contribute significantly to global anthropogenic greenhouse gas emissions, changing these natural carbon sinks into carbon sources. At present, relatively few scientifically sound studies provide dependable estimates of gaseous and fluvial carbon losses from oil palm plantations or from drained tropical peat in general. Here we present an annual (54 week) estimate of the export of dissolved and particulate organic carbon in water draining two oil palm estates and nearby stands of TPSF in Sarawak, Malaysia, subjected to varying degrees of past anthropogenic disturbance. Spectrophotometric techniques including SUVA254 (Specific Ultra-Violet Absorption) were used to gain insight into the aromaticity and subsequent bioavailability of the exported DOC. Water draining plantation and deforested land had a higher proportion of labile carbon compared to water draining forested areas. Preliminary data suggest a total fluvial DOC flux from plantations of ca. 190 g C m-2 year-1; nearly three times estimates from intact TPSFs (63 g C m-2 year-1). DOC accounted for between 86 % - 94 % of the total organic carbon lost (most of which was bioavailable). Wit et al. (2015) estimates that an average of 53 % of peat-derived DOC is decomposed and emitted as CO2, on a monthly basis. Based on these estimates our data suggests an additional 101 g CO2 m-2 may be emitted indirectly from fluvial organic carbon in degraded TPSFs per year. Overall, these findings emphasize the importance of including fluvial organic carbon fluxes when quantifying the impact of anthropogenic disturbance on the

The Brahmaputra River: a stratigraphic analysis of Holocene avulsion and fluvial valley reoccupation history

Science.gov (United States)

Hartzog, T. R.; Goodbred, S. L.

2011-12-01

The Brahmaputra River, one of the world's largest braided streams, is a major component of commerce, agriculture, and transportation in India and Bangladesh. Hence any significant change in course, morphology, or behavior would be likely to influence the regional culture and economy that relies on this major river system. The history of such changes is recorded in the stratigraphy deposited by the Brahmaputra River during the Holocene. Here we present stratigraphic analysis of sediment samples from the boring of 41 tube wells over a 120 km transect in the upper Bengal Basin of northern Bangladesh. The transect crosses both the modern fluvial valley and an abandoned fluvial valley about 60 km downstream of a major avulsion node. Although the modern Brahmaputra does not transport gravel, gravel strata are common below 20 m with fluvial sand deposits dominating most of the stratigraphy. Furthermore, the stratigraphy preserves very few floodplain mud strata below the modern floodplain mud cap. These preliminary findings will be assessed to determine their importance in defining past channel migration, avulsion frequency, and the reoccupation of abandoned fluvial valleys. Understanding the avulsion and valley reoccupation history of the Brahmaputra River is important to assess the risk involved with developing agriculture, business, and infrastructure on the banks of modern and abandoned channels. Based on the correlation of stratigraphy and digital surface elevation data, we hypothesize that the towns of Jamalpur and Sherpur in northern Bangladesh were once major ports on the Brahmaputra River even though they now lie on the banks of small underfit stream channels. If Jamalpur and Sherpur represent the outer extent of the Brahmaputra River braid-belt before the last major avulsion, these cities and any communities developed in the abandoned braid-belt assume a high risk of devastation if the next major avulsion reoccupies this fluvial valley. It is important to

Dieta de roedores sigmodontinos (Cricetidae en los bosques montanos tropicales de Huánuco, Perú

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Maggie C. Noblecilla

2013-06-01

Full Text Available Se analizó el contenido estomacal de cinco especies de roedores sigmodontinos: Akodon orophilus, Microry-zomys altissimus, M. minutus, Thomasomys notatus yT. kalinowskii, procedentes de los bosques montanos de Huánuco, Perú (2564 - 3850 m de altitud. Concluimos que A. orophiluses insectívora por haber presentado un alto volumen de artrópodos (adultos y larvas en el contenido estomacal (90,1%; mientras que T. notatusy T. kalinowskiison principalmente herbívoras por el alto volumen de materia vegetal, 89% y 67,75% respectiva-mente; y que M. altissimusy M. minutusson omnívoras por presentar volúmenes similares tanto para vegetales como para artrópodos. Thomasomys kalinowskiies considerada generalista por la mayor amplitud de nicho (4,61, mientras A. orophiluses considerada especialista por el menor valor (1,70. Akodon orophilusmostró una preferencia por el consumo de artrópodos adultos al tener un bajo coeficiente de variación (CV= 20% y también un significativo aumento en el consumo de larvas de artrópodos en la época húmeda, siendo la única especie con variación estacional en la dieta. Por otro lado, la sobreposición de nicho fue menor a 0,75 en el 80% de los pares de especies comparados, indicando una baja similitud en la dieta. La mayor similitud en la dieta se observó entre M. altissimus- T. notatus(0,822 y M. minutus - T. kalinowskii(0,816. Se concluye que estos roedores sigmodontinos, simpátricos en los bosques montanos de Huánuco, exhiben dietas disímiles, probablemente como una estrategia para evitar o aminorar la competencia interespecífica.

Fluvial biogeomorphology in the Anthropocene: Managing rivers and managing landscapes.

Science.gov (United States)

Viles, Heather

2015-04-01

Biogeomorphology considers the many, and often complex, interactions between ecological and geomorphological processes. The concept of the Anthropocene deserves greater attention by scientists working on biogeomorphology, as will be demonstrated in this talk though a focus on fluvial environments. Rivers and river systems have been the subject of long-term human interference and management across the world, often in the form of direct manipulation of biogeomorphic interactions. Up to the present three broadly-defined phases of the Anthropocene can be identified - the Palaeoanthropocene, the Industrial Revolution and the Great Acceleration. Each of these broad phases of the Anthropocene has different implications for fluvial biogeomorphology and river management. The nature and dynamics of tufa-depositing systems provide good examples of the differing Anthropocene situations and will be focused on in this talk. We may now be entering a fourth phase of the Anthropocene called 'Earth system stewardship'. In terms of better understanding and managing the biogeomorphic interactions within rivers in such a phase, an improved conceptualisation of the Anthropocene and the complex web of interactions between human, ecological and geomorphological processes is needed.

Estimación de la oferta de frutos en el gradiente vertical de un bosque del medio Caquetá, Amazonía colombiana

OpenAIRE

Nicolás Castaño Arboleda

2003-01-01

Se estimó la oferta de frutos en un bosque de tierra firme

PRODUCCIÓN DE HOJARASCA DE UN BOSQUE DE NIEBLA EN LA RESERVA NATURAL LA PLANADA (NARIÑO, COLOMBIA

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L. Vargas-Parra

2007-06-01

Full Text Available Se estimó la producción de hojarasca total, de fracciones y del menor nivel taxonómico posible de identificación de hojas en cuatro áreas de 1 ha, en el bosque de niebla de la Reserva Natural La Planaday, esta producción se relacionó con la precipitación, temperatura y humedad relativa ambiental. La producción de hojarasca se cuantificó mensualmente entre junio y noviembre de 2002, mediante la instalación de colectores distribuidos aleatoriamente en cada una de las áreas. El material colectado mensualmente se separó en hojas, ramas, partes reproductivas, epífitas y fragmentos no identificados, a cada una de las cuales se determinó su aporte en biomasa. La producción de hojarasca total estuvo dentro del rango de otros bosques montanos (7831 g/ha. Las hojas aportaron 74,4%, las ramas 10,8%, partes reproductivas 10,6%, epífitas 3,6% y fragmentos no identificados 0,6%. Las hojas se identificaron hasta el nivel de familia o género. El género que más aportó fue Clusia (40,5%. Se encontró que a mayorhumedad relativa ambiental y temperatura, menor producción en los tres niveles de hojarasca. Una mayor precipitación se relacionó con una mayor producción de fracciones, familias y géneros de hojarasca. Se sugiere realizar trabajos a largo plazo corroborando la productividad estimada con las relaciones en precipitación y humedad.

Tratamiento de los espacios fluviales urbanos andaluces en la planificación territorial y sectorial

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David González Rojas

2017-01-01

Full Text Available La recuperación y conservación de los espacios fluviales urbanos debe insertarse dentro de los procesos de planificación territorial y sectorial. El presente trabajo analiza la evolución y las transformaciones de los espacios fluviales urbanos en Andalucía durante las últimas décadas, a través del análisis de los distintos planes. Para el estudio de las relaciones entre el planeamiento territorial y sectorial y los espacios fluviales urbanos se ha realizado una recopilación de los documentos actualmente aprobados o en tramitación. En el artículo se destacan los avances durante el periodo estudiado, pero también las inercias, resistencias y nuevos problemas asociados. El esfuerzo realizado para la ordenación de los ríos a su paso por las ciudades no ha tenido su reflejo en los resultados obtenidos, siendo las interrelaciones entre la gestión del agua y del territorio (regional, subregional y municipal una cuestión no resuelta.

Optimizing sampling strategy for radiocarbon dating of Holocene fluvial systems in a vertically aggrading setting

International Nuclear Information System (INIS)

Toernqvist, T.E.; Dijk, G.J. Van

1993-01-01

The authors address the question of how to determine the period of activity (sedimentation) of fossil (Holocene) fluvial systems in vertically aggrading environments. The available data base consists of almost 100 14 C ages from the Rhine-Meuse delta. Radiocarbon samples from the tops of lithostratigraphically correlative organic beds underneath overbank deposits (sample type 1) yield consistent ages, indicating a synchronous onset of overbank deposition over distances of at least up to 20 km along channel belts. Similarly, 14 C ages from the base of organic residual channel fills (sample type 3) generally indicate a clear termination of within-channel sedimentation. In contrast, 14 C ages from the base of organic beds overlying overbank deposits (sample type 2), commonly assumed to represent the end of fluvial sedimentation, show a large scatter reaching up to 1000 14 C years. It is concluded that a combination of sample types 1 and 3 generally yields a satisfactory delimitation of the period of activity of a fossil fluvial system. 30 refs., 11 figs., 4 tabs

DINÁMICAS Y CAUSAS DE DEFORESTACIÓN EN BOSQUES DE LATINO AMÉRICA: UNA REVISIÓN DESDE 1990

OpenAIRE

Armenteras, Dolors; Rodríguez Eraso, Nelly

2014-01-01

Durante los últimos años se han publicado varios estudios sobre deforestación en Latino América, donde las tasas de pérdida de bosques, hasta la década del año 2000 en la región, por lo general son inferiores a las de otras zonas tropicales. Regularmente, los estudios de deforestación son regionales o estatales o a nivel de cuenca o microcuenca, y no permiten observar la variabilidad intrarregional presente en los trópicos americanos. En este trabajo se presenta el resultado de un meta-anális...

Optimización del costo del sistema de aprovechamiento de madera en bosques naturales de Pinus caribaea

OpenAIRE

Cándano Acosta,Fidel; Leite,Angelo Marcio Pinto; Martínez Cantón,José Luis

2012-01-01

El trabajo se realizó en bosques naturales de Pinus caribaea en áreas de la empresa forestal La Palma en la provincia de Pinar del Río - Cuba. El objetivo de la investigación fue minimizar el costo del sistema de aprovechamiento de madera a partir de la interacción entre el costo de camino y el costo de arrastre en base a la densidad de camino y patios de carga, además de la interacción del costo de camino y el costo del transporte de madera en base a la calidad de la capa de rodamiento del c...

Los Pteridófitos de un bosque subandino en el municipio de Albán, Cundinamarca (Colombia

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Luz Amparo Triana Moreno

2004-07-01

Selaginella y Huperzia con tres. De las especies encontradas Blechnum divergens, Blechnum lherminieri, Diplazium ambiguum, Elaphoglossum piloselloides, Huperzia amentacea, Hypolepis repens, Polybotrya caudata, Pteris altissima, Thelypteris grandis y Trichomanes reptans son nuevos registros para Cundinamarca. La mayoría de las especies (46% son exclusivamente terrestres y dentro de éstas las más abundantes son Asplenium flabellulatum en el bosque, Equisetum bogotense, Thelypteris rudis y Pityrogramma ebenea en el borde de las quebradas y Thelypteris rudis y Pteridium arachnoideum en los pastizales. En cuanto a las epífitas (20% la más común es  Loxoscaphe theciferum y solo Polybotrya caudata es hemiepífita.

Fluvial-aeolian interactions in sediment routing and sedimentary signal buffering: an example from the Indus Basin and Thar Desert

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East, Amy E.; Clift, Peter D.; Carter, Andrew; Alizai, Anwar; VanLaningham, Sam

2015-01-01

Sediment production and its subsequent preservation in the marine stratigraphic record offshore of large rivers are linked by complex sediment-transfer systems. To interpret the stratigraphic record it is critical to understand how environmental signals transfer from sedimentary source regions to depositional sinks, and in particular to understand the role of buffering in obscuring climatic or tectonic signals. In dryland regions, signal buffering can include sediment cycling through linked fluvial and eolian systems. We investigate sediment-routing connectivity between the Indus River and the Thar Desert, where fluvial and eolian systems exchanged sediment over large spatial scales (hundreds of kilometers). Summer monsoon winds recycle sediment from the lower Indus River and delta northeastward, i.e., downwind and upstream, into the desert. Far-field eolian recycling of Indus sediment is important enough to control sediment provenance at the downwind end of the desert substantially, although the proportion of Indus sediment of various ages varies regionally within the desert; dune sands in the northwestern Thar Desert resemble the Late Holocene–Recent Indus delta, requiring short transport and reworking times. On smaller spatial scales (1–10 m) along fluvial channels in the northern Thar Desert, there is also stratigraphic evidence of fluvial and eolian sediment reworking from local rivers. In terms of sediment volume, we estimate that the Thar Desert could be a more substantial sedimentary store than all other known buffer regions in the Indus basin combined. Thus, since the mid-Holocene, when the desert expanded as the summer monsoon rainfall decreased, fluvial-eolian recycling has been an important but little recognized process buffering sediment flux to the ocean. Similar fluvial-eolian connectivity likely also affects sediment routing and signal transfer in other dryland regions globally.

Fluvial particle characterization using artificial neural network and spectral image processing

Science.gov (United States)

Shrestha, Bim Prasad; Gautam, Bijaya; Nagata, Masateru

2008-03-01

Sand, chemical waste, microbes and other solid materials flowing with the water bodies are of great significance to us as they cause substantial impact to different sectors including drinking water management, hydropower generation, irrigation, aquatic life preservation and various other socio-ecological factors. Such particles can't completely be avoided due to the high cost of construction and maintenance of the waste-treatment methods. A detailed understanding of solid particles in surface water system can have benefit in effective, economic, environmental and social management of water resources. This paper describes an automated system of fluvial particle characterization based on spectral image processing that lead to the development of devices for monitoring flowing particles in river. Previous research in coherent field has shown that it is possible to automatically classify shapes and sizes of solid particles ranging from 300-400 μm using artificial neural networks (ANN) and image processing. Computer facilitated with hyper spectral and multi spectral images using ANN can further classify fluvial materials into organic, inorganic, biodegradable, bio non degradable and microbes. This makes the method attractive for real time monitoring of particles, sand and microorganism in water bodies at strategic locations. Continuous monitoring can be used to determine the effect of socio-economic activities in upstream rivers, or to monitor solid waste disposal from treatment plants and industries or to monitor erosive characteristic of sand and its contribution to degradation of efficiency of hydropower plant or to identify microorganism, calculate their population and study the impact of their presence. Such system can also be used to characterize fluvial particles for planning effective utilization of water resources in micro-mega hydropower plant, irrigation, aquatic life preservation etc.

Patrones de distribución de escarabajos coprófagos (Coleoptera: Scarabaeidae en relicto del bosque altoandino, Cordillera Oriental de Colombia

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Amat García Germán

1997-06-01

Full Text Available This study documents the diversity and distribution patterns of dung beetles in three relictual patches of montane forest located near the Sabana de Bogotá. 2486 individuals of 11 species in 6 genera were collected. The most abundant specie was Ontherus brevicollis, collected in two patches, followed by Dichotomius achamas collected in all three patches and Uroxys sp present only in one. Chicaque has the highest species richness with 10 species. We found a clear pattern related to habitat preferences, summarized in 3 groups: pasture beetles, edges and forest interior beetles.En este trabajo se estudió la diversidad y distribución de escarabajos coprófagos, en tres relictos de bosque altoandino de la Sabana de Bogotá. Se colectaron un total de 2486 individuos agrupados en 6 géneros y 11 especies. La especie más abundante fue Ontherus brevicollis, presente en dos de las tres áreas estudiadas, seguida por Dichotomius achamas presente en las tres áreas y Uroxys sp sólo en una. El área relictual más grande, Chicaque, presenta la mayor riqueza (10 especies, seguido por Soche con tres especies. Se encontró un claro patrón de preferencia de hábitats, resumido en tres grupos: escarabajos de potreros, de borde y de interior del bosque.

Estructura de un ecotono bosque Subalpino-pastos alpinos (Las Cutas, Ordesa, Pirineos Centrales

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Camarero, J. J.

1999-12-01

Full Text Available We describe the structure of a subalpine forest-alpine pasture ecotone in the Central Pyrenees, that includes altitudinal timberline and treeline, and it is dominated by Pinus uncinata Ram. We measured for each P. uncinata 21individual located inside a rectangular plot parallel to the slope: the location and several structural and groivth form variables (number and type of stems per individual. Then, P. uncinata individuals were classified according to their size (adults, poles, saplings and seedlings and growth form (krummholz —shrubby and multistemmed individuals—, krummholz with vertical stems. The ecotone structure was described through the study of groivth form and size changes of P. uncinata individuals across the ecotone and related to the area climate, that is characterized by maximum snow thickness in spring (April and strong N-NW-W winds. Most of living individuals were krummholz, located above the timberline in the area where seedlings were abundant. Bigger, vertical and unistemmed individuals predominated in the forest. The structure or growth form changes were sharp across the ecotone. Crown injuries due to wind effects were evident in shrubby individuals and predominated in those directions that showed stronger winds during the year. The snow-wind interaction can explain partially the location of the studied timberline that could be considered a local phenomenon. The spatial location of the different classes of individuals, the spatial interaction between seedlings and krummholz individuals, and the changes of growth form (from arborescent to shrubby or vice versa can modify the response of these P. uncinata populations to climate changes.

[es] Describimos la estructura de un ecotono bosque subalpino-pastos alpinos en los Pirineos Centrales, que incluye los límites altitudinales del bosque y del árbol y está dominado por Pinus uncinata Ram. Para cada individuo de

Insights into organic carbon oxidation potential during fluvial transport from laboratory and field experiments

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Scheingross, J. S.; Dellinger, M.; Eglinton, T. I.; Fuchs, M. C.; Golombek, N.; Hilton, R. G.; Hovius, N.; Lupker, M.; Repasch, M. N.; Sachse, D.; Turowski, J. M.; Vieth-Hillebrand, A.; Wittmann, H.

2017-12-01

Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, hydropshere, biosphere and geosphere can be a major control on atmospheric carbon dioxide concentrations. The carbon fluxes from the oxidation of rock-derived OC (a CO2 source) and erosion, transport, and burial of biospheric OC (a potential CO2 sink) during fluvial transit are approximately the same order of magnitude or larger than those from silicate weathering. Despite field data showing increasing oxidation of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport, where OC is in continual motion within an aerated river, or during periods of temporary storage in river floodplains which may be anoxic. The unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to mechanistically link geochemical and geomorphic processes which are required to develop models capable of predicting OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this knowledge gap, we investigated OC oxidation in controlled laboratory experiments and a simplified field setting. We performed experiments in annular flumes that simulate fluvial transport without floodplain storage, allowing mixtures of OC-rich and siliciclastic sediment to be transported for distances of 1000 km. Preliminary experiments exploring both rock-derived and biospheric OC sources show minimal OC oxidation during active river transport, consistent with the idea that the majority of OC loss occurs during transient floodplain storage. These results are also consistent with new field data collected in the Rio Bermejo, Argentina, a lowland river traversing 800 km with no tributary inputs, where aged floodplain deposits have 3 to 10 times lower OC concentrations compared to modern river sediments. Together our field data and experiments support the hypothesis that oxidation of OC occurs primarily during

CARACTERIZACIÓN FENOLÓGICA DE BOSQUES TROPICALES CADUCIFOLIOS USANDO INFORMACIÓN ESPECTRAL: EXPERIMENTOS CON COMPONENTES

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Marcos Casiano

2014-10-01

Full Text Available La caracterización de la fenología de la vegetación, particularmente la asociada a los bosques tropicales caducifolios, permite predecir los impactos del cambio climático y de los intercambios de carbono y agua entre la atmósfera y la vegetación, por lo que es importante modelarla. Existen diferentes métodos experimentales para caracterizar la fenología de la vegetación, sin embargo, el uso de sensores remotos permite caracterizaciones fenológicas de bajo costo y eficientes. No obstante lo anterior, la mayoría de las aplicaciones de sensores remotos cuando se usan índices de vegetación (IV solo modelan el crecimiento del follaje (etapa vegetativa y senescente y no la etapa reproductiva. Dado que la floración es crítica para la viabilidad de la vegetación, además de su valor en la apicultura, es necesario evaluarla con sensores remotos aerotransportados en el segmento visible a infrarrojo del espectro electromagnético. La revisión de experimentos y observaciones de floración muestran que los patrones temporales en las bandas del rojo (R e infrarrojo cercano (IRC son contrarios, lo cual no ocurre en los IV que caracterizan el follaje. A partir de estos análisis, se diseñó un experimento de componentes de la vegetación para simular las etapas fenológicas de pre floración, floración y post floración que hipotéticamente ocurren en un bosque caducifolio. Los resultados mostraron que es posible el desarrollo de un modelo fenológico aproximado si se usa el índice IVIS para caracterizar la inducción floral, el inicio y el pico de la floración, aunque el término de ésta se confunde con el inicio del crecimiento vegetativo del follaje.

A fast, parallel algorithm to solve the basic fluvial erosion/transport equations

Science.gov (United States)

Braun, J.

2012-04-01

Quantitative models of landform evolution are commonly based on the solution of a set of equations representing the processes of fluvial erosion, transport and deposition, which leads to predict the geometry of a river channel network and its evolution through time. The river network is often regarded as the backbone of any surface processes model (SPM) that might include other physical processes acting at a range of spatial and temporal scales along hill slopes. The basic laws of fluvial erosion requires the computation of local (slope) and non-local (drainage area) quantities at every point of a given landscape, a computationally expensive operation which limits the resolution of most SPMs. I present here an algorithm to compute the various components required in the parameterization of fluvial erosion (and transport) and thus solve the basic fluvial geomorphic equation, that is very efficient because it is O(n) (the number of required arithmetic operations is linearly proportional to the number of nodes defining the landscape), and is fully parallelizable (the computation cost decreases in a direct inverse proportion to the number of processors used to solve the problem). The algorithm is ideally suited for use on latest multi-core processors. Using this new technique, geomorphic problems can be solved at an unprecedented resolution (typically of the order of 10,000 X 10,000 nodes) while keeping the computational cost reasonable (order 1 sec per time step). Furthermore, I will show that the algorithm is applicable to any regular or irregular representation of the landform, and is such that the temporal evolution of the landform can be discretized by a fully implicit time-marching algorithm, making it unconditionally stable. I will demonstrate that such an efficient algorithm is ideally suited to produce a fully predictive SPM that links observationally based parameterizations of small-scale processes to the evolution of large-scale features of the landscapes on

Excursions in fluvial (dis)continuity

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Grant, Gordon E.; O'Connor, James E.; Safran, Elizabeth

2017-01-01

Lurking below the twin concepts of connectivity and disconnectivity are their first, and in some ways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in landscapes and rivers. We examine the historical roots of continuum and discontinuum thinking, and how much of our understanding of geomorphology rests on contrasting views of continuity and discontinuity. By continuum thinking we refer to a conception of geomorphic processes as well as geomorphic features that are expressed along continuous gradients without abrupt changes, transitions, or thresholds. Balance of forces, graded streams, and hydraulic geometry are all examples of this perspective. The continuum view has played a prominent role in diverse disciplinary fields, including ecology, paleontology, and evolutionary biology, in large part because it allows us to treat complex phenomena as orderly progressions and invoke or assume equilibrium processes that introduce order and prediction into our sciences.In contrast the discontinuous view is a distinct though complementary conceptual framework that incorporates non-uniform, non-progressive, and non-equilibrium thinking into understanding geomorphic processes and landscapes. We distinguish and discuss examples of three different ways in which discontinuous thinking can be expressed: 1) discontinuous spatial arrangements or singular events; 2) specific process domains generally associated with thresholds, either intrinsic or extrinsic; and 3) physical dynamics or changes in state, again often threshold-linked. In moving beyond the continuous perspective, a fertile set of ideas comes into focus: thresholds, non-equilibrium states, heterogeneity, catastrophe. The range of phenomena that is thereby opened up to scientific exploration similarly expands

Distribución espacio-temporal de las actividades extractivas en los bosques del ejido Caoba, Quintana Roo

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Antalia González Abraham

2012-02-01

Full Text Available Este trabajo tiene como objetivo analizar la distribución espacio-temporal de las actividades extractivas del bosque en un ejido del sur de la península de Yucatán, con el fin de evaluar su impacto potencial sobre la conservación de los recursos naturales. Se eligieron como actividades extractivas la recolecta de leña, la extracción de chicle, la extracción de madera y la cacería. Además, se incluyó a la milpa debido a que su práctica está íntimamente relacionada con la dinámica del bosque y con otras de las actividades evaluadas. Se entrevistaron a 32 ejidatarios con un cuestionario estructurado para obtener información referente a las actividades extractivas en el ejido. Posteriormente, con ayuda de un gps, se ubicaron espacialmente los sitios donde se desarrollan. Se calculó un índice de perturbación para cada actividad para elaborar un mapa de sensibilidad basado en la suma espacial de los índices de perturbación. La actividad con mayor índice de perturbación fue la milpa, debido a su desarrollo a lo largo de todo el año y frecuencia de visita de los campesinos a sus parcelas. Además, coincide espacialmente con la recolección de leña y en muchos casos con la cacería. Por el contrario la extracción de chicle fue la actividad con el menor índice de perturbación, puesto que se desarrolla una sola vez al año y durante la época menos crítica para la fauna en la región.

Large Fluvial Fans: Aspects of the Attribute Array

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Wilkinson, Justin M.

2015-01-01

In arguing for a strict definition of the alluvial fan (coarse-grained with radii less than10 km, in mountain-front settings), Blair and McPherson (1994) proposed that there is no meaningful difference between large fluvial fans (LFF) and floodplains, because the building blocks of both are channel-levee-overbank deposits. Sediment bodies at the LFF scale (greater than 100 km long, fan-shaped in planform), are relatively unstudied although greater than 160 are now identified globally. The following perspectives suggest that the significance of LFF needs to be reconsidered.

Pleistocene-Holocene sedimentation of Solimões-Amazon fluvial system between the tributaries Negro and Madeira, Central Amazon

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Eliezer Senna Gonçalves Júnior

Full Text Available ABSTRACT: In the scope of Solimões-Amazon fluvial system between the Negro and Madeira tributaries, three levels of Quaternary fluvial terraces overlie the Alter do Chão and Novo Remanso formations further than 100 km southward its current main channel. Smooth undulated topography presenting low drainages density formed by sparse secondary plain channels and rounded lakes characterizes these deposits. Internally, they show point bars morphology constituted by intercalated layers of mud (silt and clay and sand forming an inclined heterolithic stratification. The asymmetric distribution of fluvial terraces allied to the records of old scroll-bars features and paleochannels in many extensions of the Solimões River suggests the predominance of a meander pattern between 240 to 6 kyears. On the other hand, the development of the current anabranching pattern took place in the last six kyears due to the Holocene sea-level rise, besides the action of neotectonics and rainforest establishment related to the increase of humidity in Amazonia.

Effects of change in primary forest cover on armadillo (Cingulata, Mammalia burrow use in the Central Amazon Efectos del cambio en la cobertura de bosque primario sobre el uso de las madrigueras por los armadillos (Cingulata, Mammalia en la Amazonia Central

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María Clara Arteaga

2012-03-01

Full Text Available Transformation of primary forest to other vegetation types alters the availability and distribution of resources, and thus affects their use by species that inhabit the forest. Although armadillos are important earthmover mammals in the Amazon forest, and their burrows play an important physical and ecological role in the ecosystem, the impact of loss of primary forest cover on these organisms has been poorly understood. In order to evaluate the effects of change in the primary forest cover on burrow use by armadillos, we performed 2 censuses in 33 plots within 12 sites of different vegetation cover characteristics, and recorded burrow density and current use. A total of 109 armadillo burrows were found; the sites with higher percentages of primary forest cover showed a larger number of active burrows, although burrow density and the probability of establishing new burrows remained unaffected by this variable. Our results show that areas with higher quantities of primary forest habitat show more intense use by armadillos, probably due to the permanence time of individuals. These findings suggest that the viability of armadillo populations, as well as the role that these animals play within the ecosystem, may be affected in disturbed areas.La transformación del bosque primario a otro tipo de vegetación cambia la disponibilidad y distribución de los recursos, afectando su uso por especies que habitan el bosque. Los armadillos son el principal grupo de mamíferos escavadores del Amazonas y sus madrigueras cumplen un papel físico y ecológico en el ecosistema. Sin embargo, no se conoce el impacto de la pérdida del bosque sobre estos organismos. Con el fin de evaluar el efecto de los cambios en la cobertura de bosque primario sobre el uso de sus madrigueras, realizamos 2 censos en 33 parcelas dentro de 12 localidades con diferentes coberturas vegetales y reportamos la densidad y el estado de uso de las madrigueras. Encontramos 109 madrigueras y

A new ‘superassemblage’ model explaining proximal-to-distal and lateral facies changes in fluvial environments, based on the Proterozoic Sanjauli Formation (Lesser Himalaya, India

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Ananya Mukhopadhyay

2016-09-01

Full Text Available Facies analysis of fluvial deposits of the Proterozoic Sanjauli Formation in the Lesser Himalaya was combined with an architectural analysis. On this basis, a model was developed that may be applied to other fluvial systems as well, whether old or recent. The new model, which might be considered as an assemblage of previous models, explains lateral variations in architecture and facies but is not in all respects consistent with the standard fluvial models. The Sanjauli fluvial model is unique in that it deals with lateral facies variations due to shifts of the base-level along with fluctuations in accommodation space owing to changes in palaeoclimate.

Respiración microbial y de raíces en suelos de bosques tropicales primarios y secundarios (porce, colombia).

OpenAIRE

Ramírez Palacio, Álvaro Andrés; Moreno Hurtado, Flavio Humberto

2011-01-01

Los suelos son el mayor reservorio de carbono en los ecosistemas terrestres y a su vez la mayor fuente de CO2 atmosférico, el cual es producido mediante un proceso denominado respiración del suelo. El objetivo de este trabajo fue estimar las tasas de respiración del suelo y sus componentes (respiración de raíces y de microorganismos), y evaluar el control que sobre las tasas de emisión de CO2 ejercen factores como la humedad y la temperatura del suelo, en bosques primarios (BP) y secundarios ...

Diversidad y composición de Chiropteros en un paisaje fragmentado de bosque seco en Rivas, Nicaragua

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Arnulfo Medinal

2004-08-01

Full Text Available Uno de los problemas ambientales que han suscitado mayor interés mundial en los últimos años, es la pérdida de biodiversidad como consecuencia de las actividades humanas, ya sea de manera directa (sobreexplotación o indirecta (alteración del hábitat (Moreno, 2001. Existen algunos análisis que muestran claramente cómo el número de especies (diversidad disminuye al reducirse o fragmentarse el área, a consecuencia de procesos a través de los cuales, los remanentes del bosque original, de tamaños y formas variables, quedan inmersos en una matriz de hábitats transformados (Cattan, 2002.

Assessing the Effects of Climate on Global Fluvial Discharge Variability

Science.gov (United States)

Hansford, M. R.; Plink-Bjorklund, P.

2017-12-01

Plink-Bjorklund (2015) established the link between precipitation seasonality and river discharge variability in the monsoon domain and subtropical rivers (see also Leier et al, 2005; Fielding et al., 2009), resulting in distinct morphodynamic processes and a sedimentary record distinct from perennial precipitation zone in tropical rainforest zone and mid latitudes. This study further develops our understanding of discharge variability using a modern global river database created with data from the Global Runoff Data Centre (GRDC). The database consists of daily discharge for 595 river stations and examines them using a series of discharge variability indexes (DVI) on different temporal scales to examine how discharge variability occurs in river systems around the globe. These indexes examine discharge of individual days and monthly averages that allows for comparison of river systems against each other, regardless of size of the river. Comparing river discharge patterns in seven climate zones (arid, cold, humid subtropics, monsoonal, polar, rainforest, and temperate) based off the Koppen-Geiger climate classifications reveals a first order climatic control on discharge patterns and correspondingly sediment transport. Four groupings of discharge patterns emerge when coming climate zones and DVI: persistent, moderate, seasonal, and erratic. This dataset has incredible predictive power about the nature of discharge in fluvial systems around the world. These seasonal effects on surface water supply affects river morphodynamics and sedimentation on a wide timeframe, ranging from large single events to an inter-annual or even decadal timeframe. The resulting sedimentary deposits lead to differences in fluvial architecture on a range of depositional scales from sedimentary structures and bedforms to channel complex systems. These differences are important to accurately model for several reasons, ranging from stratigraphic and paleoenviromental reconstructions to more

Reservoir architecture and tough gas reservoir potential of fluvial crevasse-splay deposits

NARCIS (Netherlands)

Van Toorenenburg, K.A.; Donselaar, M.E.; Weltje, G.J.

2015-01-01

Unconventional tough gas reservoirs in low-net-to-gross fluvial stratigraphic intervals may constitute a secondary source of fossil energy to prolong the gas supply in the future. To date, however, production from these thin-bedded, fine-grained reservoirs has been hampered by the economic risks

Extreme Changes in Stream Geomorphic Conditions induced by Fluvial Scour in Bridges

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Özcan, O.; Ozcan, O.

2016-12-01

The numerous complexities associated with bridge scour have caused scour to be one of the most active topics of stream geomorphic research. The assessment of local scouring mechanism around bridge piers provides information for decision-making regarding the pile footing design, predicting the safety of bridges under critical scoured conditions, and as a result, may help prevent unnecessary loses. In the study, bridge design plans and HEC-RAS modeling were used for the assessment of changes in stream geomorphic conditions. The derived fluvial scour depths were compared with the field measurements and the empirical formula which is based on stream flow discharge rate, streambed condition and shape of river. Preliminary results revealed that bridge damage resulting from the flood event in 2003 induced substantial scour around bridge piles. Afterwards, significant stream bed change was observed under the influence of fluvial scour in another flood occurred in 2009. Consequently, geomorphic conditions of the stream bed should be considered in the structural design of the bridges.

Results of radiocarbon dating of Holocene fluvial sediments from Northeastern Bohemia

International Nuclear Information System (INIS)

Silar, J.; Zeman, A.

1989-01-01

Samples of wood and charcoal from the latest Holocene fluvial sediments under the lowest surface of alluvial plains were dated by radiocarbon in order to check paleomagnetic data at four sites in northeastern Bohemia. The results are presented as funcorrected 14 C ages and dendrochronologically corrected ages. Two samples were recent. 4 figs., 1 tab., 3 refs

Climatic implications of correlated upper Pleistocene glacial and fluvial deposits on the Cinca and Gallego rivers, NE Spain

Energy Technology Data Exchange (ETDEWEB)

Lewis, Claudia J [Los Alamos National Laboratory; Mcdonald, Eric [NON LANL; Sancho, Carlos [NON LANL; Pena, Jose- Luis [NON LANL

2008-01-01

We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gallego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 {+-} 5 ka, 64 {+-} 11 ka, and 36 {+-} 3 ka (from glacial till) and 20 {+-} 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 {+-} 21 ka, 97 {+-} 16 ka, 61 {+-} 4 ka, 47 {+-} 4 ka, and 11 {+-} 1 ka, and in the Gallego River valley at 151 {+-} 11 ka, 68 {+-} 7 ka, and 45 {+-} 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 {+-} 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 {+-} 4 ka) and Gallego (68 {+-} 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to (1) global climate changes controlled by insolation, (2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and (3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian peninsula. The model of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.

Reflexiones y enfoques en la conservación y restauración de ríos: georrestauración y pensamiento fluvial

OpenAIRE

Horacio, Jesús

2015-01-01

En los últimos años las sociedades más avanzadas se comienzan a replantear los principios y métodos aplicados para la gestión de los ríos. Este cambio de tendencia en la forma de pensar acerca de nuestro patrimonio fluvial es lo que se denomina en este trabajo: pensamiento fluvial. Este pensamiento implica derrocar ideas incompletas o erróneas sobre qué es un río y aceptarlo como un sistema natural dinámico. Pero el pensamiento fluvial invita también a discutir sobre la forma de conservar y r...

Fluvial geomorphology and aquatic-to-terrestrial Hg export are weakly coupled in small urban streams of Columbus, Ohio

Science.gov (United States)

Sullivan, S. Mažeika P.; Boaz, Lindsey E.; Hossler, Katie

2016-04-01

Although mercury (Hg) contamination is common in stream ecosystems, mechanisms governing bioavailability and bioaccumulation in fluvial systems remain poorly resolved as compared to lentic systems. In particular, streams in urbanized catchments are subject to fluvial geomorphic alterations that may contribute to Hg distribution, bioaccumulation, and export across the aquatic-to-terrestrial boundary. In 12 streams of urban Columbus, Ohio, we investigated the influence of fluvial geomorphic characteristics related to channel geometry, streamflow, and sediment size and distribution on (1) Hg concentrations in sediment and body burdens in benthic larval and adult emergent aquatic insects and (2) aquatic-to-terrestrial contaminant transfer to common riparian spiders of the families Pisauridae and Tetragnathidae via changes in aquatic insect Hg body burdens as well as in aquatic insect density and community composition. Hydrogeomorphic characteristics were weakly related to Hg body burdens in emergent insects (channel geometry) and tetragnathid spiders (streamflow), but not to Hg concentrations in sediment or benthic insects. Streamflow characteristics were also related to emergent insect density, while wider channels were associated with benthic insect community shifts toward smaller-bodied and more tolerant taxa (e.g., Chironomidae). Thus, our results provide initial evidence that fluvial geomorphology may influence aquatic-to-terrestrial contaminant Hg transfer through the collective effects on emergent insect body burdens as well as on aquatic insect community composition and abundance.

Fluvial incision by the Qingyijiang River on the northern fringe of Mt. Huangshan, eastern China: Responses to weakening of the East Asian summer monsoon

Science.gov (United States)

Hu, Chunsheng; Liu, Shaochen; Hu, Chenqi; Xu, Guanglai; Zhou, Yingqiu

2017-12-01

This paper focuses on climatic and tectonic controls to determine their relative importance to the Quaternary fluvial incision by the Qingyijiang River, eastern China. The Qingyijiang, which is one of longest tributaries of the lower Yangtze River, drains the northern piedmont of Mt. Huangshan. A field survey focused on three natural sections of the Qingyijiang in the Jingxian basin, where a well-preserved sequence of one alluvial platform (P) and three fluvial terraces (T3, T2, and T1) is presented. The heights of the platform and the terraces above river level are 65, 40, 20, and 7 m respectively. In this study, electron spin resonance (ESR), optical stimulated luminescence (OSL), and palaeomagnetic dating were applied to reconstruct the fluvial incision history of the Qingyijiang and evaluate the possible influence of tectonic uplift and/or climate change on the fluvial incision. The main results show that (1) the ages of P, T3, T2, and T1 were determined to be ∼ 1300, ∼ 900, ∼ 600, and ∼ 1.5 ka respectively, corresponding to four incision events in the Qingyijiang; (2) the East Asian summer monsoon (EASM) experienced four significant weakening events at 1300, 900, 600, and ∼ 1.5 ka, according to previous research. Correspondingly, we propose that four significant increased periods of regional precipitation occurred at 1300, 900, 600, and ∼ 1.5 ka in the study area because of the negative correlation between the intensity of the EASM and regional precipitation from 1960 to 2012; and (3) fluvial incision by the Qingyijiang arose as a result of the weakening of the EASM in combination with tectonic uplift, determined by matching fluvial incision history of the Qingyijiang with tectonic movement and EASM change. In addition, the weakening of the EASM climatically triggered fluvial incision by the Qingyijiang. This study supports the conclusion that major fluvial incision has been climatically triggered; however, it also suggests that the mechanism of

Avifauna del bosque mesófilo de montaña del noreste de Hidalgo, México Avifauna of the tropical montane cloud forest of northeastern Hidalgo, Mexico

Directory of Open Access Journals (Sweden)

Miguel Angel Martínez-Morales

2007-06-01

Full Text Available Este trabajo presenta los resultados de un inventario avifaunístico realizado de 1997 a 1999 en fragmentos de bosque mesófilo de montaña del noreste de Hidalgo, México. Se registraron 41 familias y 181 especies de aves mediante observaciones visuales y auditivas en 2 057 puntos de conteo, lo que representó el 98% de las especies esperadas en el área de estudio, para el período y método de muestreo utilizado. Se detectaron 16 especies restringidas al bosque mesófilo, 11 endémicas de México y 3 de distribución restringida. Adicionalmente, con base en la legislación mexicana vigente, 28 de las especies registradas están incluidas dentro de alguna categoría de riesgo de conservación. Esta comunidad de aves estuvo dominada por especies de aves pequeñas, raras (poco abundantes y residentes. Es probable que las más vulnerables de sufrir extinciones locales sean las especies raras y restringidas al bosque mesófilo, donde están incluidas las 3 especies de distribución restringida (Dendrortyx barbatus, Glaucidium sanchezi y Cyanolyca nana. La avifauna del bosque mesófilo de esta región incluye al 40% de la avifauna estatal, lo que destaca la relevancia de este tipo de vegetación y una urgente necesidad de establecer estrategias de manejo para su conservación.This study shows the results of bird census carried out from 1997 to 1999 in cloud forest fragments of northeastern Hidalgo, Mexico. Forty-one bird families and 181 species were recorded through visual and acoustic detections in 2 057 point counts. This represents 98% of the expected species richness for the sampling period and method used. Sixteen species restricted to the cloud forest were detected, 11 Mexican endemic species, and 3 restricted-range species were recorded. Additionally, 28 species are included within some category of conservation concern according to the present Mexican legislation. This bird community was dominated by small, rare (low in abundance, and

El efecto del fuego y las características topográficas sobre la vegetación y las propiedades del suelo en la zona de transición entre bosques y pastizales de las sierras de Córdoba, Argentina

OpenAIRE

Giorgis, Melisa Adriana; Cingolani, Ana María; Cabido, Marcelo Ruben

2016-01-01

En el contexto actual de cambio climático, el estudio de la dinámica de las zonas de transición entre bosques y pastizales tiene un papel fundamental, tanto a nivel científico como en la planificación del manejo de los ecosistemas. En este trabajo evaluamos el efecto combinado del fuego, la exposición de ladera y la posición topográfica sobre la vegetación y los suelos en una zona de transición entre bosques y pastizales en las montañas de Córdoba. Para ello elegimos cuatro áreas con diferent...

Phosphorus and nitrogen loading depths in fluvial sediments following manure spill simulations

Science.gov (United States)

Manure spills that enter streams can devastate the aquatic ecosystem. The depth of nitrogen (N) and phosphorus (P) loading in fluvial sediments following a manure spill have not been documented. Thus, the objectives of this study were (i) to determine the depth of N and P contamination as a result o...

Middle Moscovian climate of eastern equatorial Pangea recorded in paleosols and fluvial architecture

Czech Academy of Sciences Publication Activity Database

Opluštil, S.; Lojka, R.; Rosenau, N.A.; Strnad, L.; Sýkorová, Ivana

2015-01-01

Roč. 440, DEC (2015), s. 328-352 ISSN 0031-0182 Institutional support: RVO:67985891 Keywords : Carboniferous paleoclimate * fluvial architectures * paleosols * geochemistry Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.525, year: 2015 http://www.sciencedirect.com/science/article/pii/S0031018215004939

Relación entre suelos y estructura del bosque en la Amazonía colombiana

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Bayron R Calle-Rendón

2011-09-01

Full Text Available Las diferencias estructurales del bosque pueden ser el producto de variaciones ambientales a diferentes escalas, entre ellas los suelos. Para evaluar tal asociación, se usaron los datos de estructura del bosque y de suelos de una parcela de 6ha establecida en un bosque de tierra firme de la Amazonía colombiana. Las variables edáficas y estructurales se redujeron con un análisis de componentes principales (ACP y un análisis de regresión múltiple verificó si existía asociación entre los componentes edáficos y estructurales del ACP. La regionalización de las variables de estudio se verificó con variogramas isotrópicos; además, se construyeron mapas de distribución espacial. El ACP de las variables estructurales identificó dos componentes: dosel y sotobosque, los cuales explicaron el 43.9 y 36.2% de la varianza total, respectivamente; para las variables edáficas los cuatro primeros componentes explicaron globalmente el 81.9% de la varianza total. Los análisis de regresión mostraron que tanto el dosel como el sotobosque se asocian con mayores contenidos de arena y baja fertilidad del suelo (pSoil and forest structure in the Colombian Amazon. Forests structural differences could result of environmental variations at different scales. Because soils are an important component of plant’s environment, it is possible that edaphic and structural variables are associated and that, in consequence, spatial autocorrelation occurs. This paper aims to answer two questions: (1 are structural and edaphic variables associated at local scale in a terra firme forest of Colombian Amazonia? and (2 are these variables regionalized at the scale of work? To answer these questions we analyzed the data of a 6ha plot established in a terra firme forest of the Amacayacu National Park. Structural variables included basal area and density of large trees (diameter≥10cm (Gdos and Ndos, basal area and density of understory individuals (diameter<10cm (Gsot

High temporal resolution in situ measurement of the effective particle size characteristics of fluvial suspended sediment.

Science.gov (United States)

Williams, N D; Walling, D E; Leeks, G J L

2007-03-01

This paper reports the use of a LISST-100 device to monitor the effective particle size characteristics of suspended sediment in situ, and at a quasi-continuous temporal resolution. The study site was located on the River Exe at Thorverton, Devon, UK. This device has not previously been utilized in studies of fluvial suspended sediment at the storm event scale, and existing studies of suspended sediment dynamics have not involved such a high temporal resolution for extended periods. An evaluation of the field performance of the instrument is presented, with respect to innovative data collection and analysis techniques. It was found that trends in the effective particle size distribution (EPSD) and degree of flocculation of suspended sediment at the study site were highly complex, and showed significant short-term variability that has not previously been documented in the fluvial environment. The collection of detailed records of EPSD facilitated interpretation of the dynamic evolution of the size characteristics of suspended sediment, in relation to its likely source and delivery and flocculation mechanisms. The influence of measurement frequency is considered in terms of its implications for future studies of the particle size of fluvial suspended sediment employing in situ data acquisition.

Characterization and 3D reservoir modelling of fluvial sandstones of the Williams Fork Formation, Rulison Field, Piceance Basin, Colorado, USA

International Nuclear Information System (INIS)

Pranter, Matthew J; Vargas, Marielis F; Davis, Thomas L

2008-01-01

This study describes the stratigraphic characteristics and distribution of fluvial deposits of the Upper Cretaceous Williams Fork Formation in a portion of Rulison Field and addresses 3D geologic modelling of reservoir sand bodies and their associated connectivity. Fluvial deposits include isolated and stacked point-bar deposits, crevasse splays and overbank (floodplain) mudrock. Within the Williams Fork Formation, the distribution and connectivity of fluvial sandstones significantly impact reservoir productivity and ultimate recovery. The reservoir sandstones are primarily fluvial point-bar deposits interbedded with shales and coals. Because of the lenticular geometry and limited lateral extent of the reservoir sandstones (common apparent widths of ∼500–1000 ft; ∼150–300 m), relatively high well densities (e.g. 10 acre (660 ft; 200 m) spacing) are often required to deplete the reservoir. Heterogeneity of these fluvial deposits includes larger scale stratigraphic variability associated with vertical stacking patterns and structural heterogeneities associated with faults that exhibit lateral and reverse offsets. The discontinuous character of the fluvial sandstones and lack of distinct marker beds in the middle and upper parts of the Williams Fork Formation make correlation between wells tenuous, even at a 10 acre well spacing. Some intervals of thicker and amalgamated sandstones within the middle and upper Williams Fork Formation can be correlated across greater distances. To aid correlation and for 3D reservoir modelling, vertical lithology proportion curves were used to estimate stratigraphic trends and define the stratigraphic zonation within the reservoir interval. Object-based and indicator-based modelling methods have been applied to the same data and results from the models were compared. Results from the 3D modelling indicate that sandstone connectivity increases with net-to-gross ratio and, at lower net-to-gross ratios (<30%), differences exist in

La Conicidad de los Arboles y Algunas Posibles Aplicaciones en el Manejo de Bosques

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González Pérez Huberto

1988-09-01

Full Text Available La descripción de la conicidad de los árboles se plantea como una herramienta tecnológica de gran utilidad en el manejo de bosques. Se analizan tanto algunos factores del árbol y del rodal que afectan la conicidad de los árboles, como la utilización de la técnica de las "spline" cúbicas para la descripción del perfil y el cálculo del volumen del árbol individual. Se describe una metodología para determinar ecuaciones de volumen a partir de la aplicación de la técnica de las "spline" cúbicas y se propone un modelo simple de conicidad deducido de interpretaciones geométricas del comportamiento de la conicidad de árboles excurrentes. Se presentan algunos resultados experimentales haciendo especial referencia al ciprés (Cupressus lusitanica una especie de gran interés en los programas de reforestación en la regin andina de Colombia.

Composición y distribución espacio-temporal de escarabajos coprófagos (Coleoptera: Scarabaeidae: Sarabaeinae en el bosque municipal de Mariquita, Tolima, Colombia

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Paula Valeria Fuentes Medina

2004-07-01

gremial de la comunidad de los escarabajos coprófagos. Los resultados mostraron variaciones en dichos parámetros a lo largo de los muestreos en cada una de las zonas (bosque y abierta. Los disturbios y la creación de áreas abiertas afectan la diversidad y las poblaciones de tales organismos, y se ratificó el uso de la fauna de escarabajos coprófagos como bioindicadores.

Anotaciones sobre el Clima de los Bosques de Guandal del Delta del Río Patía

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Del Valle Arango Jorge Ignacio

1994-09-01

Full Text Available Este ensayo intenta describir el clima del litoral Pacifico sur colombiano de una manera más precisa y empleando un cúmulo mayor de registros que en otros trabajos anteriores. Con esta base se realiza una clasificación bioclimática para los bosques de guandal del delta del río Patía. En cuanto a la lluvia se hace énfasis no sólo en los promedios mensuales y anuales sino en su oscilación y desviaciones estándar con el fin de evidenciar lo variable de tan importante factor climático. Finalmente se elaboran isoyetas para la región las cuales consideramos consistentes con la información disponible.

A Late Pleistocene linear dune dam record of aeolian-fluvial dynamics at the fringes of the northwestern Negev dunefield

Science.gov (United States)

Roskin, Joel; Bookman, Revital; Friesem, David; Vardi, Jacob

2017-04-01

The paper presents a late Pleistocene aeolian-fluvial record within a linear dune-like structure that partway served as a dune dam. Situated along the southern fringe of the northwestern Negev desert dunefield (Israel) the structure's morphology, orientation, and some of its stratigraphic units partly resemble adjacent west-east extending vegetated linear dunes. Uneven levels of light-colored, fine-grained fluvial deposits (LFFDs) extend to the north and south from the flanks of the studied structure. Abundant Epipalaeolithic sites line the fringes of the LFFDs. The LFFD microstructures of fine graded bedding and clay blocky peds indicate sorting and shrinking of saturated clays in transitional environments between low energy flows to shallow standing water formed by dunes damming a mid-sized drainage system. The structure's architecture of interchanging units of sand with LFFDs indicates interchanging dominances between aeolian sand incursion and winter floods. Sand mobilization associated with powerful winds during the Heinrich 1 event led to dune damming downstream of the structure and within the structure to in-situ sand deposition, partial fluvial erosion, reworking of the sand, and LFFD deposition. Increased sand deposition led to structure growth and blockage of its drainage system that in turn accumulated LFFD units up stream of the structure. Extrapolation of current local fluvial sediment yields indicate that LFFD accretion up to the structure's brim occurred over a short period of several decades. Thin layers of Geometric Kebaran (c. 17.5-14.5 ka cal BP) to Harifian (12-11 ka BP) artifacts within the structure's surface indicates intermittent, repetitive, and short term camping utilizing adjacent water along a timespan of 4-6 kyr. The finds directly imply that the NW Negev LFFDs formed in dune-dammed water bodies which themselves were formed following events of vegetated linear dune elongation. LFFD accumulation persisted as a result of dune dam

Abundancia y Biomasa de Lombrices de Tierra en dos Ecosistemas Intervenidos del Bosque Trópica l Húmedo, Bluefields Las lombrices de tierra son el intestino de la tierra Gilbert White, 1789.

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Gladys Luna

2012-09-01

Full Text Available Muchos estudios han demostrado que las lombrices de tierra (Anelidae son el componente más abundante de la macrofauna del suelo y desempeñan funciones ecológicas dentro de él.El objetivo fue evaluar la abundancia y biomasa de lombrices de tierra en dos hábitats del bosque tropical húmedo con diferentes usos de suelo en la ciudad de Bluefields, Región Autónoma Atlántico Sur (RAAS. En cada hábitat se seleccionaron dos micro-hábitats: uno con sombra y otro sin sombra y en cada uno se delimitaron tres subparcelas de 1pie2 cada una, y una profundidad de 10 cm, ubicadas al azar y a una distancia mínima de 15 m entre sí.Cada muestra de suelo se tamizó y se extrajeron, se midieron y se pesaron los individuos por subparcela. El número de lombrices registradas fue mayor en el hábitat de área reforestada que en el hábitat de bosque, pero ocurrió lo contrario con respecto al tamaño promedio de los individuos.La mayor disponibilidad de materia orgánica en el bosque puede explicar el mayor tamaño de los individuos en este sitio.En aquellos suelos que han sufrido alteraciones antrópicas, como en el campus universitario, las comunidades de lombrices han experimentado cambios extremos denotando así una mala salud; sin embargo, estas comunidades se están recuperando, especialmente en los microhabitats con sombra.

Transport and redistribution of Chernobyl fallout radionuclides by fluvial processes: some preliminary evidence

International Nuclear Information System (INIS)

Walling, D.E.; Bradley, S.B.

1988-01-01

Several measurements of 137 Cs concentrations in suspended sediment transported by the River Severn during the post-Chernobyl period and in recent channel and floodplain deposits along the river emphasise the potential significance of fluvial processes in the transport and concentration of fallout radionuclides. (author)

The impact of disturbance on the dynamics of fluvial processes in mountain landscapes

Czech Academy of Sciences Publication Activity Database

Langhammer, J.; Hartvich, Filip; Kliment, Z.; Jeníček, M.; Bernsteinová (Kaiglová), J.; Vlček, L.; Su, Y.; Štych, P.; Miřijovský, J.

2015-01-01

Roč. 21, č. 1 (2015), s. 105-116 ISSN 1211-7420 Institutional support: RVO:67985891 Keywords : runoff * fluvial dynamics * forest disturbance * climate change * Bohemian Forest Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://www.npsumava.cz/gallery/31/9345-sg_21_1_langhammeretal.pdf

Modelling the impact of regional uplift and local tectonics on fluvial terrace preservation.

NARCIS (Netherlands)

Viveen, W.; Schoorl, J.M.; Veldkamp, A.; Balen, van R.T.

2014-01-01

A terrace formation model (TERRACE) combined with a longitudinal river profile model (FLUVER) was used to simulate fluvial terrace formation and preservation in the northwest Iberian lower Miño River basin under the influence of three tectonic conditions; namely regional vertical uplift, local basin

(L. Benth. en bosques secundarios en Escárcega, Campeche, México

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J. L. López-Torres

2005-01-01

Full Text Available El T´zalam Lysiloma latisiliquum (L. Benth. en la región de Escárcega, Campeche, México, es la especie más abundante y con mayor importancia económica en bosques secundarios derivados de selva mediana subperennifolia, después haber sido intervenida mediante el sistema rosa-tumba-quema. El objetivo de este trabajo es analizar el comportamiento del crecimiento en diámetro de esta especie, en un periodo de 20 años de desarrollo. A partir de la variable diámetro normal (d1.3, agrupada en categorías diamétricas, se estimaron los incrementos anuales medio, máximo y mínimo para cada categoría. Los resultados indican que en el escenario más ventajoso se requiere de 10.6 años para que los árboles pasen de categoría reserva a categoría aprovechable y, en promedio, es necesario de 21.5 años para alcanzar la misma condición. El incremento en diámetro fue, en promedio, de 0.511 cm y se clasifica como medio.

Effects of Wildfire on Fluvial Sediment Regime through Perturbations in Dry-Ravel

Science.gov (United States)

Florsheim, J. L.; Chin, A.; Kinoshita, A. M.; Nourbakhshbeidokhti, S.; Storesund, R.; Keller, E. A.

2015-12-01

In steep chaparral ecosystems with Mediterranean climate, dry ravel is a natural process resulting from wildfire disturbance that supplies sediment to fluvial systems. When dense chaparral vegetation burns, sediment accumulated on steep hillslopes is released for dry-season transport (dry ravel) down steep hillslopes during or soon after the wildfire. Results of a field study in southern California's Transverse Ranges illustrate the effect of wildfire on fluvial sediment regime in an unregulated chaparral system. Big Sycamore Canyon in the steep Santa Monica Mountains burned during the May 2013 Springs Fire and experienced one small sediment-transporting stormflow during the following winter. We conducted pre- and post-storm field campaigns during the fall and winter following the fire to quantify the effect of wildfire on the fluvial sediment regime. We utilized a sediment mass balance approach in which: 1) sediment supply, consisting primarily of dry ravel-derived deposits composed of relatively fine grained-sediment, was measured in the upstream basin and in the hillslope-channel margin adjacent to the study reach; 2) changes in storage in the study reach were quantified by analyzing the difference between pre- and post-storm channel topography derived from Terrestrial LiDAR Scanning (TLS) and field surveys; and 3) transport from the study reach was estimated as the difference between supply and change in storage where uncertainty is estimated using calculated sediment transport as a comparison. Results demonstrate channel deposition caused by changes in the short-term post-wildfire sediment regime. The increased sediment supply and storage are associated with significant changes in morphology, channel bed-material characteristics, and ecology. These results suggest that dry-ravel processes are an important factor to consider in post-wildfire sediment management.

Facies architecture and high resolution sequence stratigraphy of an aeolian, fluvial and shallow marine system in the Pennsylvanian Piauí Formation, Parnaíba Basin, Brazil

Science.gov (United States)

Vieira, Lucas Valadares; Scherer, Claiton Marlon dos Santos

2017-07-01

The Pennsylvanian Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in the cratonic sag Parnaíba basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description and logging of outcrops. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, shoreface and shoreface-shelf transition. Through correlation of stratigraphic surfaces, the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or shoreface and shoreface-shelf transition deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by shoreface-shelf transition and shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. The Lower Sequence is characterized by aeolian deposits of the LST and an aggradational base followed by a progressive transgression, defining a general TST. The Upper Sequence is characterized by fluvial deposits and interfluve pedogenesis concurring with the aeolian deposits of the LST and records a subtle regression followed by transgression. The main control on sedimentation in the Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

Fluvial organic carbon flux from an eroding peatland catchment, southern Pennines, UK

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R. R. Pawson

2008-03-01

Full Text Available This study investigates for the first time the relative importance of dissolved organic carbon (DOC and particulate organic carbon (POC in the fluvial carbon flux from an actively eroding peatland catchment in the southern Pennines, UK. Event scale variability in DOC and POC was examined and the annual flux of fluvial organic carbon was estimated for the catchment. At the event scale, both DOC and POC were found to increase with discharge, with event based POC export accounting for 95% of flux in only 8% of the time. On an annual cycle, exports of 35.14 t organic carbon (OC are estimated from the catchment, which represents an areal value of 92.47 g C m⁻² a⁻¹. POC was the most significant form of organic carbon export, accounting for 80% of the estimated flux. This suggests that more research is required on both the fate of POC and the rates of POC export in eroding peatland catchments.

The Amazonian Craton and its influence on past fluvial systems (Mesozoic-Cenozoic, Amazonia)

NARCIS (Netherlands)

Hoorn, C.; Roddaz, M.; Dino, R.; Soares, E.; Uba, C.; Ochoa-Lozano, D.; Mapes, R.; Hoorn, C.; Wesselingh, F.P.

2010-01-01

The Amazonian Craton is an old geological feature of Archaean/Proterozoic age that has determined the character of fluvial systems in Amazonia throughout most of its past. This situation radically changed during the Cenozoic, when uplift of the Andes reshaped the relief and drainage patterns of

New Mesoscale Fluvial Landscapes - Seismic Geomorphology and Exploration

Science.gov (United States)

Wilkinson, M. J.

2013-01-01

Megafans (100-600 km radius) are very large alluvial fans that cover significant areas on most continents, the surprising finding of recent global surveys. The number of such fans and patterns of sedimentation on them provides new mesoscale architectures that can now be applied on continental fluvial depositional systems, and therefore on. Megafan-scale reconstructions underground as yet have not been attempted. Seismic surveys offer new possibilities in identifying the following prospective situations at potentially unsuspected locations: (i) sand concentrations points, (ii) sand-mud continuums at the mesoscale, (iii) paleo-valley forms in these generally unvalleyed landscapes, (iv) stratigraphic traps, and (v) structural traps.

Estructura y composición de la vegetación del bosque de niebla de Copalillos, San Luis Potosí, México

OpenAIRE

Fortanelli-Martínez, Javier; García-Pérez, José; Castillo-Lara, Pedro

2014-01-01

Se presenta la lista florística y se describe la estructura de un bosque de niebla en Copalillos, San Luis Potosí, el cual, hasta hace muy poco tiempo estuvo ausente en la cartografía de vegetación existente. Se registraron 199 especies, correspondientes a 165 géneros y 91 familias botánicas. La estructura vertical mostró tres estratos arbóreos, uno arbustivo y otro herbáceo. Las especies dominantes en el arbóreo superior fueron Liquidambar styraciflua, Quercus germana y Q. pinnativenulosa. E...

Transport and deposition of plutonium-contaminated sediments by fluvial processes, Los Alamos Canyon, New Mexico

International Nuclear Information System (INIS)

Graf, W.L.

1996-01-01

Between 1945 and 1952 the development of nuclear weapons at Los Alamos National Laboratory, New Mexico, resulted in the disposal of plutonium into the alluvium of nearby Acid and (to a lesser degree) DP Canyons. The purpose of this paper is to explore the connection between the disposal sites and the main river, a 20 km link formed by the fluvial system of Acid, Pueblo, DP, and Los Alamos Canyons. Empirical data from 15 yr of annual sediment sampling throughout the canyon system has produced 458 observations of plutonium concentration in fluvial sediments. These data show that, overall, mean plutonium concentrations in fluvial sediment decline from 10,000 fCi/g near the disposal area to 100 fCi/g at the confluence of the canyon system and the Rio Grande. Simulations using a computer model for water, sediment, and plutonium routing in the canyon system show that discharges as large as the 25 yr event would fail to develop enough transport capacity to completely remove the contaminated sediments from Pueblo Canyon. Lesser flows would move some materials to the Rio Grande by remobilization of stored sediments. The simulations also show that the deposits and their contaminants have a predictable geography because they occur where stream power is low, hydraulic resistance is high, and the geologic and/or geomorphic conditions provide enough space for storage. 38 refs., 13 figs., 1 tab

Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics.

NARCIS (Netherlands)

Cunningham, A.C.; Wallinga, J.; Versendaal, Alice; Makaske, A.; Middelkoop, H.; Hobo, N.

2015-01-01

The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics

NARCIS (Netherlands)

Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

2015-01-01

The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could

Algunos aspectos ecológicos de “tarántulas” (Araneae: Theraphosidae en dos tipos de bosques en San Juan Bautista, Loreto, Perú

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Pablo Reátegui Suárez

2014-12-01

Full Text Available Los resultados muestran la presencia de tarántulas del área de concesión de la empresa Perufish Aquarium EIRL, quebrada Yanayacu, río Itaya, Loreto. Reportándose un total de 5 especies de la familia Theraphosidae. Las 5 especies estuvieron en los bosques de colinas bajas moderadamente disectadas y 3 de estas en el bosque de colinas bajas ligeramente disectadas. Las especies más abundantes fueron Megaphobema velvetosoma con 64.3% y Cyriocosmus sellatus con 35%. El tamaño promedio de la abertura de las madrigueras varió en relación al tamaño de las especies, la más grande correspondió a Megaphobema velvetosoma con un promedio de 66,6 mm, y la más pequeña a Acanthoscurria ferina con un promedio de 21 mm. La temperatura del interior de las madrigueras varió de 25,2°C a 25,7°C y la humedad relativa de 88% a 88,7%. Las madrigueras se encontraron en el suelo con una capa de hojarasca que varió de 2,7 a 4,9 cm. Las especies de tarántulas se distribuyeron formando grupos en las zonas evaluadas. Las muestras de tarántulas se encuentran depositadas en la Universidad Nacional de la Amazonia Peruana y en la empresa Perufish Aquarium EIRL.

Study on fine geological modelling of the fluvial sandstone reservoir in Daqing oilfield

Energy Technology Data Exchange (ETDEWEB)

Zhoa Han-Qing [Daqing Research Institute, Helongjiang (China)

1997-08-01

These paper aims at developing a method for fine reservoir description in maturing oilfields by using close spaced well logging data. The main productive reservoirs in Daqing oilfield is a set of large fluvial-deltaic deposits in the Songliao Lake Basin, characterized by multi-layers and serious heterogeneities. Various fluvial channel sandstone reservoirs cover a fairly important proportion of reserves. After a long period of water flooding, most of them have turned into high water cut layers, but there are considerable residual reserves within them, which are difficult to find and tap. Making fine reservoir description and developing sound a geological model is essential for tapping residual oil and enhancing oil recovery. The principal reason for relative lower precision of predicting model developed by using geostatistics is incomplete recognition of complex distribution of fluvial reservoirs and their internal architecture`s. Tasking advantage of limited outcrop data from other regions (suppose no outcrop data available in oilfield) can only provide the knowledge of subtle changing of reservoir parameters and internal architecture. For the specific geometry distribution and internal architecture of subsurface reservoirs (such as in produced regions) can be gained only from continuous infilling logging well data available from studied areas. For developing a geological model, we think the first important thing is to characterize sandbodies geometries and their general architecture`s, which are the framework of models, and then the slight changing of interwell parameters and internal architecture`s, which are the contents and cells of the model. An excellent model should possess both of them, but the geometry is the key to model, because it controls the contents and cells distribution within a model.

On the Application of an Enthalpy Method to the Evolution of Fluvial Deltas Under Sea-Level Changes

Science.gov (United States)

Anderson, W.; Lorenzo-Trueba, J.; Voller, V. R.

2017-12-01

Fluvial deltas are composites of two primary sedimentary environments: a depositional fluvial region and an offshore region. The fluvial region is defined by two geomorphic moving boundaries: an alluvial-bedrock transition (ABT), which separates the sediment prism from the non-erodible bedrock basement, and the shoreline (SH), where the delta meets the ocean. The trajectories of these boundaries in time and space define the evolution of the shape of the sedimentary prism, and are often used as stratigraphic indicators, particularly in seismic studies, of changes in relative sea level and the identification of stratigraphic sequences. In order to better understand the relative role of sea-level variations, tectonics, and sediment supply on the evolution of these boundaries, we develop a forward stratigraphic model that captures the dynamic behavior of the fluvial surface and treats the SH and ABT as moving boundaries (i.e., internal boundaries whose location must be determined as part of the solution to the overall morphological evolution problem). This forward model extends a numerical technique from heat transfer (i.e., enthalpy method), previously applied to the evolution of sedimentary basins, to account for sea-level changes. The mathematics of the approach are verified by comparing predictions from the numerical model with both existing and newly developed closed form analytical solutions. Model results support previous work, which suggests that the migration of the ABT can respond very differently to the sea-level signal. This response depends on factors such as sediment supply and delta length, which can vary greatly between basins. These results can have important implications for the reconstruction of past sea-level changes from the stratigraphic record of sedimentary basins.

Cronología de la regeneración del bosque tropical seco en Santa Rosa, Guanacaste, Costa Rica: II. La vegetación en relación con el suelo

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Jorge A Leiva

2009-09-01

Full Text Available Se estudió la sucesión del bosque tropical seco (BTS de Santa Rosa, Guanacaste, Costa Rica, en cinco sitios boscosos secundarios y tres bosques maduros. Se analizó el efecto de la clase de suelo sobre la estructura del bosque y la diversidad de especies arbóreas. Los ocho sitios sucesionales estaban localizados a lo largo de una cronosecuencia de regeneración (10, 15, 20, 40, 60 and >100 años en la que se identificaron 17 pedones y seis órdenes de suelos con moderada a alta fertilidad, clasificados como Entisoles y Vertisoles, aunque los Mollisoles, Alfisoles, Inceptisoles y Ultisoles estuvieron presentes también. Se establecieron 130 parcelas de 10 por 50 m (0.05 ha, 20 en cada bosque secundario y 10 en cada bosque antiguo (6.5 ha en total, de acuerdo con la topografía. Se midió el diámetro a la altura de pecho (dap de todos los individuos presentes en cada parcela, la altura dominante y el área basal (m2ha-1, usando dos poblaciones: latizales (dap ≥ 1 y Chronology of tropical dry forest regeneration in Santa Rosa, Guanacaste, Costa Rica. II. Vegetation in relation to the soil. Tropical dry forest (TDF succession was monitored in Santa Rosa, Costa Rica. We analyzed the effect of soil type on forest structure and diversity. Eight seasonally-dry TDF sites located along a successional chrono-sequence (10, 15, 20, 40, 60 and >100 years were examined in relation to 17 soil pedons and six soil orders. Soils had moderate to high fertility and were classified as Entisols and Vertisols, although Mollisols, Alfisols, Inceptisols and Ultisols were also present. One-hundred and thirty 500 m2 plots were established, 20 plots in secondary and 10 plots in mature TDFsites. Diameter at breast height (dbh and total tree height were measured for saplings (dbh ≥1 and <5 cm, shrubs and trees (dbh ≥5 cm. With the exception of two sites (40 and 60 years, soil type did not have significant effects on forest structure. However, tree diversity measured

EFECTO DEL MANEJO FORESTAL EN LA DIVERSIDAD Y COMPOSICIÓN ARBÓREA DE UN BOSQUE TEMPLADO DEL NOROESTE DE MÉXICO

OpenAIRE

Javier Hernández-Salas; Óscar A. Aguirre-Calderón; Eduardo Alanís-Rodríguez; Javier Jiménez-Pérez; Eduardo J. Treviño-Garza; Marco A. González-Tagle; Concepción Luján-Álvarez; Jesús M. Olivas-García; L. Alfonso Domínguez-Pereda

2013-01-01

En la presente investigación se evaluó el efecto de las prácticas silvícolas en la diversidad y composición de especies arbóreas de un bosque templado del noroeste de México. Para ello, 46 parcelas fueron evaluadas cada 10 años: 1986, 1996 y 2006. Se estimaron los índices de diversidad alfa y beta de la comunidad arbórea, y la abundancia, dominancia, frecuencia e índice de valor de importancia de cada especie (IVI). Los resultados muestran que el aprovechamiento forestal modifica la diversida...

Estimación de la oferta de frutos en el gradiente vertical de un bosque del medio Caquetá, Amazonia colombiana

OpenAIRE

Nicolás Castaño Arbleda; Julio Betancur Betancur

2004-01-01

Durante el año 2001 se estimó la oferta de frutos en un bosque de tierra firme de la Amazonia colombiana. Se muestrearon siete parcelas de 50 x 50 m cada una (1,75 ha), en las que se censaron todos los individuos fructificados. En total se encontraron 1.154 individuos en fruto, correspondientes a 196 especies y 57 familias. En cada ciclo de muestreo  se produjeron en promedio 15.212 frutos/ha y 16,1 kg/ha de peso seco de la cosecha. Para estimar la fructificación de cada especie y familia se ...

Assessing Potential Algal Blooms in a Shallow Fluvial Lake by Combining Hydrodynamic Modelling and Remote-Sensed Images

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Monica Pinardi

2015-04-01

Full Text Available Shallow fluvial lakes are dynamic ecosystems shaped by physical and biological factors and characterized by the coexistence of phytoplankton and macrophytes. Due to multiple interplaying factors, understanding the distribution of phytoplankton in fluvial lakes is a complex but fundamental issue, in the context of increasing eutrophication, climate change, and multiple water uses. We analyze the distribution of phytoplankton by combining remotely sensed maps of chlorophyll-a with a hydrodynamic model in a dammed fluvial lake (Mantua Superior Lake, Northern Italy. The numerical simulation of different conditions shows that the main hydrodynamic effects which influence algal distribution are related to the combined effect of advection due to wind forces and local currents, as well as to the presence of large gyres which induce recirculation and stagnation regions, favoring phytoplankton accumulation. Therefore, the general characters of the phytoplankton horizontal patchiness can be inferred from the results of the hydrodynamic model. Conversely, hyperspectral remote-sensing products can be used to validate this model, as they provide chlorophyll-a distribution maps. The integration of ecological, hydraulic, and remote-sensing techniques may therefore help the monitoring and protection of inland water quality, with important improvements in management actions by policy makers.

Analysis of Fluvial Bed Sediments Along the Apalachicola River, Florida through Field Reconnaissance Studies

Science.gov (United States)

Passeri, D.; Hagen, S. C.; Daranpob, A.; Smar, D. E.

2011-12-01

River competence is an important parameter in understanding sediment transport in fluvial systems. Competence is defined as the measure of a stream's ability to transport a certain maximum grain size of sediment. Studies have shown that bed sediment particle size in rivers and streams tends to vary spatially along the direction of stream flow. Over a river section several reaches long, variability of sediment particle sizes can be seen, often becoming finer downstream. This phenomenon is attributed to mechanisms such as local control of stream gradient, coarse tributary sediment supply or particle breakdown. Average particle size may also be smaller in tributary sections of rivers due to river morphology. The relationship between river mean velocity and particle size that can be transported has also been explored. The Hjulstrom curve classifies this relationship by relating particle size to velocity, dividing the regions of sedimentation, transportation, and erosion. The curve can also be used to find values such as the critical erosion velocity (the velocity required to transport particles of various sizes in suspension) and settling velocity (the velocity at which particles of a given size become too heavy to be transported and fall out of suspension, consequently causing deposition). The purpose of this research is to explore the principles of river competence through field reconnaissance collection and laboratory analysis of fluvial sediment core samples along the Apalachicola River, FL and its distributaries. Sediment core samples were collected in the wetlands and estuarine regions of the Apalachicola River. Sieve and hydrometer analyses were performed to determine the spatial distribution of particle sizes along the river. An existing high resolution hydrodynamic model of the study domain was used to simulate tides and generate river velocities. The Hjulstrom curve and the generated river velocities were used to define whether sediment was being transported

Rapid fluvial incision of a late Holocene lava flow: Insights from LiDAR, alluvial stratigraphy, and numerical modeling

Science.gov (United States)

Sweeney, Kristin; Roering, Joshua J.

2016-01-01

Volcanic eruptions fundamentally alter landscapes, paving over channels, decimating biota, and emplacing fresh, unweathered material. The fluvial incision of blocky lava flows is a geomorphic puzzle. First, high surface permeability and lack of sediment should preclude geomorphically effective surface runoff and dissection. Furthermore, past work has demonstrated the importance of extreme floods in driving incision via column toppling and plucking in columnar basalt, but it is unclear how incision occurs in systems where surface blocks are readily mobile. We examine rapid fluvial incision of the Collier lava flow, an andesitic Holocene lava flow in the High Cascades of Oregon. Since lava flow emplacement ∼1600 yr ago, White Branch Creek has incised bedrock gorges up to 8 m deep into the coherent core of the lava flow and deposited >0.2 km3 of sediment on the lava flow surface. Field observation points to a bimodal discharge regime in the channel, with evidence for both annual snowmelt runoff and outburst floods from Collier glacier, as well as historical evidence of vigorous glacial meltwater. To determine the range of discharge events capable of incision in White Branch Creek, we used a mechanistic model of fluvial abrasion. We show that the observed incision implies that moderate flows are capable of both initiating channel formation and sustaining incision. Our results have implications for the evolution of volcanic systems worldwide, where glaciation and/or mass wasting may accelerate fluvial processes by providing large amounts of sediment to otherwise porous, sediment-starved landscapes.

La construccion social del paisaje cultural. Entre el Paseo del Bosque y el Estadio de Estudiantes de la Plata

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Mabel Irma Contin

2011-01-01

Full Text Available Este artículo presenta los resultados de una investigación sobre las transformaciones y tensiones en el espacio público central cuyo propósito ha sido descubrir, finalmente, los valores en juego en la gestión contemporánea del paisaje cultural urbano. Dicha investigación toma como caso de estudio la ciudad de La Plata (Argentina y su principal parque urbano, el Paseo del Bosque. Éste contiene en uno de sus bordes al estadio de fútbol del Club Estudiantes de La Plata, uno de los equipos emblemáticos de la ciudad, cuyo proyecto de renovación ha originado un conflicto urbano de una dificultad sin precedentes.

O SUB-BOSQUE DE REFLORESTAMENTOS DE PINUS EM SÍTIOS DEGRADADOS DA REGIÃO DA FLORESTA ESTACIONAL DECIDUAL DO RIO GRANDE DO SUL

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Franz H. Andrae

2005-08-01

Full Text Available Analisou-se o sub-bosque de 12 povoamentos de Pinus sp. e um de Araucaria angustifolia O.Ktze., crescendo em solos degradados pelo uso agrícola na chamada 4a Colônia do Rio Grande do Sul. A Araucaria foi semeada diretamente, um dos povoamentos de Pinus, de 10 anos, resultou de uma renovação natural, os demais provêm de plantios de 25 a 30 anos atrás. Em 575 parcelas de 25 m² cada, distribuídas sistematicamente nos povoamentos, foram levantados o estrato arbóreo e a vegetação inferior, classificada em estratos de 0,3 a 1,3 m e maior que 1,3 m; no estrato inferior a 0,3 m somente a renovação natural de Pinus foi contada. A vegetação interna dos povoamentos se compôs de 121 espécies lenhosas, incluindo espécies desde comuns até nobres, mas também ornamentais ou frutíferas nativas e exóticas. Um bom número de espécies, porém, ocorreu com poucos representantes. Além disso registrou-se a presença freqüente de espécies não-arbóreas como ervas, gramas, samambaias e cipós. O número de espécies e o grau de cobertura do sub-bosque não dependiam da densidade do estrato superior de pinheiros. A abundância e a freqüência das espécies não variavam significativamente entre parcelas do centro dos povoamentos e da faixa periférica. O padrão de distribuição espacial das plantas dentro dos povoamentos foi quantificado pelo Índice de Cox. O Índice de Shannon foi usado como medida da diversidade em espécies; pelo Índice de Sörensen foi estudada a semelhança dos povoamentos. Conclui-se que plantios de exóticas nessa região não somente podem ser de interesse para os agricultores pelo elevado potencial produtivo em madeira, como também significam manchas de inesperada biodiversidade numa paisagem degradada. A riqueza do sub-bosque possivelmente se deve á extensão reduzida desses povoamentos.

Applying fluvial geomorphology to river channel management: Background for progress towards a palaeohydrology protocol

Science.gov (United States)

Gregory, K. J.; Benito, G.; Downs, P. W.

2008-06-01

Significant developments have been achieved in applicable and applied fluvial geomorphology as shown in publications of the last three decades, analyzed as the basis for using results of studies of environmental change as a basis for management. The range of types of publications and of activities are more pertinent to river channel management as a result of concern with sustainability, global climate change, environmental ethics, ecosystem health concepts and public participation. Possible applications, with particular reference to river channel changes, include those concerned with form and process, assessment of channel change, urbanization, channelization, extractive industries, impact of engineering works, historical changes in land use, and restoration with specific examples illustrated in Table 1. In order to achieve general significance for fluvial geomorphology, more theory and extension by modelling methods is needed, and examples related to morphology and process characteristics, integrated approaches, and changes of the fluvial system are collected in Table 2. The ways in which potential applications are communicated to decision-makers range from applicable outputs including publications ranging from review papers, book chapters, and books, to applied outputs which include interdisciplinary problem solving, educational outreach, and direct involvement, with examples summarized in Table 3. On the basis of results gained from investigations covering periods longer than continuous records, a protocol embracing palaeohydrological inputs for application to river channel management is illustrated and developed as a synopsis version (Table 4), demonstrating how conclusions from geomorphological research can be expressed in a format which can be considered by managers.

Tamarix, hydrology and fluvial geomorphology: Chapter 7

Science.gov (United States)

Auerbach, Daniel A.; Merritt, David M.; Shafroth, Patrick B.; Sher, Anna A; Quigley, Martin F.

2013-01-01

This chapter explores the impact of hydrology and fluvial geomorphology on the distribution and abundance of Tamarix as well as the reciprocal effects of Tamarix on hydrologic and geomorphic conditions. It examines whether flow-regime alteration favors Tamarix establishment over native species, and how Tamarix stands modify processes involved in the narrowing of river channels and the formation of floodplains. It begins with an overview of the basic geomorphic and hydrologic character of rivers in the western United States before analyzing how this setting has contributed to the regional success of Tamarix. It then considers the influence of Tamarix on the hydrogeomorphic form and function of rivers and concludes by discussing how a changing climate, vegetation management, and continued water-resource development affect the future role of Tamarix in these ecosystems.

A method of fingerprinting the sources of fluvial sediment using environmental radionuclides. A case study of Tsuzura river watershed

International Nuclear Information System (INIS)

Mizugaki, Shigeru; Onda, Yuichi; Fukuyama, Taijiro; Koga, Satoko; Hiramatsu, Shinya

2006-01-01

To study the fluvial sediment sources in forested watershed in Shikoku Island, Japan, the concentration of Cs-137 and Pb-210 ex and U decay series radionuclides were analyzed. The study area in the midstream of Shimanto River basin, located 700 km southwest of Tokyo. The 0.33 km 2 area watershed ranges in elevation from 170 m to 560 m above sea level. The soil sampling was conducted in hillslopes in various locations such as landslide scar, soil surface in unmanaged Hinoki (Chamacecyparis obtusa) plantation and unsealed forest road, and detailed sampling in the stream bed and bank was also conducted in several tributaries. Time-integrated suspended sediment sampler was adopted to obtain enough volume of sample to determine the radionuclides. The activities of Cs-137, Pb-210, Pb-214 and Bi-214 of soils and fluvial sediments were determined by gamma-ray spectrometry. Correction for the effect of particle size distribution and organic matter content on the radionuclides were conducted to compare the radionuclides concentration between the soils of potential suspended sediment sources and fluvial sediments. It was found that there were significant differences of Cs-137 and Pb-210 ex concentration between forest floor or runoff sediment and forest road or stream bank. The Cs-137 and Pb-210 ex concentration of suspended sediment varied among them, suggesting the possibility of fingerprinting the sources of fluvial sediment by Cs-137 and Pb-210 ex . (author)

Stable carbon isotope analysis of fluvial sediment fluxes over two contrasting C(4) -C(3) semi-arid vegetation transitions.

Science.gov (United States)

Puttock, Alan; Dungait, Jennifer A J; Bol, Roland; Dixon, Elizabeth R; Macleod, Christopher J A; Brazier, Richard E

2012-10-30

Globally, many drylands are experiencing the encroachment of woody vegetation into grasslands. These changes in ecosystem structure and processes can result in increased sediment and nutrient fluxes due to fluvial erosion. As these changes are often accompanied by a shift from C(4) to C(3) vegetation with characteristic δ(13) C values, stable isotope analysis provides a promising mechanism for tracing these fluxes. Input vegetation, surface sediment and fluvially eroded sediment samples were collected across two contrasting C(4) -C(3) dryland vegetation transitions in New Mexico, USA. Isotope ratio mass spectrometric analyses were performed using a Carlo Erba NA2000 analyser interfaced to a SerCon 20-22 isotope ratio mass spectrometer to determine bulk δ(13) C values. Stable isotope analyses of contemporary input vegetation and surface sediments over the monitored transitions showed significant differences (p fluvially eroded sediment from each of the sites, with no significant variation between surface sediment and eroded sediment values. The significant differences in bulk δ(13) C values between sites were dependent on vegetation input. Importantly, these values were robustly expressed in fluvially eroded sediments, suggesting that stable isotope analysis is suitable for tracing sediment fluxes. Due to the prevalent nature of these dryland vegetation transitions in the USA and globally, further development of stable isotope ratio mass spectrometry has provided a valuable tool for enhanced understanding of functional changes in these ecosystems. Copyright © 2012 John Wiley & Sons, Ltd.

Influencia de tres tipos de vegetación riberena en el control de la erosión fluvial en Pantanos de Centla, México

NARCIS (Netherlands)

Sepúlveda, A.; Geissen, V.; Ochoa-Gaona, S.; Jarquin-Sanchez, A.; Hernandez de la Cruz, S.; Zamora-Cornelio, L.F.

2009-01-01

Influence of three types of riparian vegetation on fluvial erosion control in Pantanos de Centla, Mexico. Wetlands constitute very important ecological areas. The aim of this study was to quantify the soil losses due to fluvial erosion from 2006 to 2008 in two riverbanks under three types of vegetal

Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

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Woronko Barbara

2015-06-01

Full Text Available We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.

The role of the matrix-edge dynamics of amphibian conservation in tropical montane fragmented landscapes La dinámica del borde-matriz en bosques mesófilos de montaña fragmentados y su papel en la conservación de los anfibios

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Georgina Santos-Barrera

2011-06-01

Full Text Available Edge effects play a key role in forest dynamics in which the context of the anthropogenic matrix has a great influence on fragment connectivity and function. The study of the interaction between edge and matrix effects in nature is essential to understand and promote the colonization of some functional groups in managed ecosystems. We studied the dynamics of 7 species of frogs and salamanders occurring in 8 ecotones of tropical montane cloud forest (TMCF which interact with adjacent managed areas of coffee and corn plantations in Guerrero, southern Mexico. A survey effort of 196 man/hours along 72 transects detected 58 individuals of 7 amphibian species and 12 environmental and structural variables were measured. The diversity and abundance of amphibians in the forest mostly depended on the matrix context adjacent to the forest patches. The forest interior provided higher relative humidity, leaf litter cover, and canopy cover that determined the presence of some amphibian species. The use of shaded coffee plantations was preferred by the amphibians over the corn plots possibly due to the maintenance of native forest arboreal elements, low management rate and less intensity of disturbance in the coffee plantations than in the corn plots. Shaded coffee plantations reduce the edge effects in TMCF, improve the connectivity between TMCF fragments and increase habitat quality for the forest interior amphibian species. Future wildlife management research should take into account edge and matrix effects to understand species dynamics which move along anthropogenic-natural ecotones in managed ecosystems, thus prioritizing sites to buffer edge effects and increase habitat quality in remaining natural ecosystems.El efecto de borde es un evento clave en la dinámica de algunos bosques, la matriz que rodea a los fragmentos de bosque tiene una gran importancia en el funcionamiento y conectividad de estos fragmentos. El conocimiento de las interacciones entre

Chronology of fluvial terrace sequences for large Atlantic rivers in the Iberian Peninsula (Upper Tagus and Duero drainage basins, Central Spain)

Science.gov (United States)

Silva, Pablo G.; Roquero, Elvira; López-Recio, Mario; Huerta, Pedro; Martínez-Graña, Antonio M.

2017-06-01

This work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central Spain draining to the Atlantic Ocean (Upper Tagus and Duero drainage basins). Both basins evolved under similar Mediterranean climatic conditions throughout the Pleistocene and present comparable number of fluvial terraces (16-17) after excluding the higher terrace levels of the Tagus (T1-T5) entrenched in the Raña surface. These higher ;rañizo terraces; was formed in response to fan-head trenching in this high alluvial piedmont (+220 m) and therefore not properly controlled by Quaternary fluvial downcutting. The study accomplishes the implementation of multiple regression analyses for terrace height-age relationships. To transform relative terrace heights above the present river thalwegs (i.e. +100 m) in numerical ages a ;height-age transference function; has been developed on the basis of preliminary statistical geochronological approaches proposed for Central Spain. The resultant height-age transference function gather 73 published geochronological data for terrace sequences, featuring a 3rd Order Polynomial Function (R2 0.90). This function describes the overall trend of valley downcutting for the last c. 2.3 Ma in Central Spain and is used to assign numerical ages to terrace levels at different relative elevation.

Arsenic and fluvial biofilms: biogeochemistry, toxicity and biotic interactions

OpenAIRE

Barral Fraga, Laura

2017-01-01

Basándonos en los conocimientos actuales sobre la ecotoxicología del biofilm y la biogeoquímica del arsénico en ecosistemas dulceacuícolas, esta tesis estudió, bajo concentraciones ambientales realistas, i) el papel de los biofilms bentónicos en la biodisponibilidad y destoxificación del arsénico, ii) los efectos tóxicos del arsénico sobre la estructura y función de los biofilms bentónicos fluviales, prestando especial atención a las respuestas de las diatomeas, y iii) la interacción entre es...

El papel del pastoreo en la reducción de la carga de combustible en los bosques de la Vall d'Alinyà

OpenAIRE

Forestalia (Grup de recerca)

2014-01-01

Títol variant: The role of extensive ranching in reducing fuel loads in the forests of the Alinyà Valley Este estudio pretende mostrar como una gestión mediante pastura extensiva puede ayudar entre otros beneficios ecológicos y sociales a disminuir la carga de combustible forestal, reducir el riesgo de incendios y mejorar la biodiversidad. El objetivo principal es determinar si la ganadería extensiva es una opción viable como método reductor de la carga combustible en los bosques de la Val...

Contribution of radioactive tracers to sediment transport study in fluvial flows

International Nuclear Information System (INIS)

Wilson Junior, G.

1995-01-01

The uses of radioactive tracers in sediment transport studies are presented in this report to evidence the importance of: Open channel researches, to describe field applications in waterways; Simultaneous utilization of classical methods and radiotracer techniques, in fluvial and estuarine environments; Development of radiotracers techniques applied in dynamic sedimentology. The report illustrated with some experiments carried out in Brazil and France, in open channel and natural flows. (author). 5 refs, 4 figs

Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

Science.gov (United States)

Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua J.

2015-01-01

Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

Fluvial diffluence episodes reflected in the Pleistocene tufa deposits of the River Piedra (Iberian Range, NE Spain)

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Vázquez-Urbez, M.; Pardo, G.; Arenas, C.; Sancho, C.

2011-01-01

The Pleistocene deposits of the valley of the River Piedra (NE Spain) are represented by thick tufas with small amounts of detrital material; the development of these deposits correlates with marine isotopic stages 9, 7, 6, and 5. The sedimentary scenario in which they formed mostly corresponded to stepped fluvial systems with barrage-cascade and associated dammed areas separated by low gradient fluvial stretches. Mapping and determining the sedimentology and chronology of these deposits distinguished two main episodes of fluvial diffluence that originated as a result of the temporary blockage of the river — a consequence of the vertical growth of tufa barrages in the main channel. In both episodes, water spilt out toward a secondary course from areas upstream of barrages where the water level surpassed the height of the divide between the main and secondary course. As a consequence, extensive and distinct tufa deposits with very varied facies formed over a gently inclined area toward and, indeed, within the secondary course. The hydrology of this secondary course was episodic, fed only by surface water. The two diffluence episodes detected occurred during MIS 7 and 7-6 and were interrupted by incision events, reflected by detrital deposits at the base of each tufa sedimentation stage in the main channel. Incision, which caused the breakage of the barrages, allowed water to again flow through the main channel. No evidence of diffluence was seen in any younger (MIS 5 to present-day) tufa deposits. The proposed diffluence model might help explain other carbonate fluvial systems in which (1) tufas appear in areas with no permanent water supply, and (2) tufas are absent over extensive areas despite conditions favourable to their formation.

Characterizing Feedbacks Between Environmental Forcing and Sediment Characteristics in Fluvial and Coastal Systems

Science.gov (United States)

Feehan, S.; Ruggiero, P.; Hempel, L. A.; Anderson, D. L.; Cohn, N.

2016-12-01

Characterizing Feedbacks Between Environmental Forcing and Sediment Characteristics in Fluvial and Coastal Systems American Geophysical Union, 2016 Fall Meeting: San Francisco, CA Authors: Scott Feehan, Peter Ruggiero, Laura Hempel, and Dylan Anderson Linking transport processes and sediment characteristics within different environments along the source to sink continuum provides critical insight into the dominant feedbacks between grain size distributions and morphological evolution. This research is focused on evaluating differences in sediment size distributions across both fluvial and coastal environments in the U.S. Pacific Northwest. The Cascades' high relief is characterized by diverse flow regimes with high peak/flashy flows and sub-threshold flows occurring in relative proximity and one of the most energetic wave climates in the world. Combining analyses of both fluvial and coastal environments provides a broader understanding of the dominant forces driving differences between each system's grain size distributions, sediment transport processes, and resultant evolution. We consider sediment samples taken during a large-scale flume experiment that simulated floods representative of both high/flashy peak flows analogous to runoff dominated rivers and sub-threshold flows, analogous to spring-fed rivers. High discharge flows resulted in narrower grain size distributions while low flows where less skewed. Relative sediment size showed clear dependence on distance from source and the environments' dominant fluid motion. Grain size distributions and sediment transport rates were also quantified in both wave dominated nearshore and aeolian dominated backshore portions of Long Beach Peninsula, Washington during SEDEX2, the Sandbar-aEolian-Dune EXchange Experiment of summer 2016. The distributions showed spatial patterns in mean grain size, skewness, and kurtosis dependent on the dominant sediment transport process. The feedback between these grain size

Quantifying bleaching for zero-age fluvial sediment: A Bayesian approach

International Nuclear Information System (INIS)

Cunningham, Alastair C.; Evans, Mary; Knight, Jasper

2015-01-01

Luminescence dating of sediment requires the sand grains to have been exposed to sunlight prior to their most recent burial. Under fluvial transport, the amount of sunlight exposure may not always be sufficient to reset the luminescence signal, a phenomenon known as ‘partial bleaching'. The extent of bleaching is dependent on a combination of geomorphic, sedimentological and fluvial processes. If bleaching can be quantified, and the relationship with these processes understood, it could potentially be used as a new environmental proxy for changes in the dynamics of river systems. Here, we use a recently developed statistical model to evaluate the extent of bleaching, by inferring the proportion of well-bleached grains in the small-aliquot population. We sampled low-flow and flood deposits at a single site on the River Sabie, South Africa. We show that the low-flow sediment is almost perfectly bleached (>80% of grains well bleached), while sediment at flood elevations is partially bleached (20–70 % of grains well bleached). The degree of bleaching may show a relationship with flood magnitude as defined by elevation above normal river level, and we speculate on the causes of variability in bleaching between flood samples. - Highlights: • We sampled modern river sediment from low-flow and flood elevations. • The unbleached OSL dose was measured. • Bayesian methods can estimate the proportion of well-bleached grains. • Low-flow sediments are well bleached; flood deposits are poorly bleached.

Glacial vs. Interglacial Period Contrasts in Midlatitude Fluvial Systems, with Examples from Western Europe and the Texas Coastal Plain

Science.gov (United States)

Blum, M.

2001-12-01

Mixed bedrock-alluvial valleys are the conveyor belts for sediment delivery to passive continental margins. Mapping, stratigraphic and sedimentologic investigations, and development of geochronological frameworks for large midlatitude rivers of this type, in Western Europe and the Texas Coastal Plain, provide for evaluation of fluvial responses to climate change over the last glacial-interglacial period, and the foundations for future quantitative evaluation of long profile evolution, changes through time in flood magnitude, and changes in storage and flux of sediments. This paper focuses on two issues. First, glacial vs. interglacial period fluvial systems are fundamentally different in terms of channel geometry, depositional style, and patterns of sediment storage. Glacial-period systems were dominated by coarse-grained channel belts (braided channels in Europe, large-wavelength meandering in Texas), and lacked fine-grained flood-plain deposits, whereas Holocene units, especially those of late Holocene age, contain appreciable thicknesses of flood-plain facies. Hence, extreme overbank flooding was not significant during the long glacial period, most flood events were contained within bankfull channel perimeters, and fine sediments were bypassed through the system to marine basins. By contrast, extreme overbank floods have been increasingly important during the relatively short Holocene, and a significant volume of fine sediment is sequestered in flood-plain settings. Second, glacial vs. interglacial systems exhibit different amplitudes and frequencies of fluvial adjustment to climate change. High-amplitude but low-frequency adjustments characterized the long glacial period, with 2-3 extended periods of lateral migration and sediment storage puncuated by episodes of valley incision. Low-amplitude but high-frequency adjustments have been more typical of the short Holocene, when there has been little net valley incision or net changes in sediment storage, but

EL MEDIO NATURAL: ESTUDIO DE SU EVOLUCIÓN A TRAVÉS DE TEXTOS HISTÓRICOS (EL TERRITORIO DEL REAL SITIO Y BOSQUE DE RIOFRÍO, SEGOVIA

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María Gloria Sanz Sanjosé

2004-12-01

Full Text Available Resumen:El objetivo fundamental es mostrar como cualquier espacio geográfico ha tenido en tiempo históricouna evolución en la que han intervenido tanto los factores naturales como la intervención delhombre y la sociedad de cada momento. El espacio geográfico estudiado es el Real Sitio y Bosquede Riofrío (Segovia y su entorno. El tiempo histórico incluye el intervalo entre la promulgaciónde dos Reales Ordenanzas: la Real Ordenanza de montes y plantíos, en 1748 y la Real Ordenanzapara la veda de la caza, pesca y aprovechamiento de los Reales Bosques, en 1774.Palabras clave:Paisaje forestal, Reales Bosques, Real Ordenanza, Real Sitio.Abstract:The Fundamental aim is to see how any geographical area has had, through time, an evolutionin which natural factors have intervened as much  as those of man and society at any time. The geographicalarea studied is the Royal grounds and forest of Riofno (Segovia and its setting. Thepoint in history is the establishment of said Royal Grounds and the publication of two Royal Ordinances:the Royal Ordinance of moutains and planlations in 1748 and Royal Ordinance for theprohibition of hunting,fishing and use of Royal Forests, in 1774.Key words:Forest landscape, Royal Forests, Royal Ordinace, Royal Grounds.Résumé:Le but fondamental est de voir comment n'importe que1 espace geographique a eu dans le tempshistorique une évolution dont les agents son autant les facteurs de la nature que I'action de I'hommeet la societé de I'époque. L'espace geographique étudié est le Real Sitio (Lieu Royal et Bois deRiofno (Segovie et son entourage. L'époque historique est I'établissement du Real Sitio et la promulgationde deux Ordonnances Royales : L'Ordonnance Royale de monts etplantations en 1748et I'Ordonnace Royale pour la periode de  fa chasse et la peche e! le profit des Bois Royales, en1774.Mots-Clés:Paysage forestier, Reales Bosques (Bois Royals, Real Ordenanza (Ordonnance Royale, RealSitio (Lieu Royal.

Distribución de animales en las capas bajas de un bosque húmedo tropical de la región Carare - Opón (Santander, Colombia

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Sturm Helmut

1970-09-01

Full Text Available 1. El presente trabajo es una investigación previa que se restringe a los grupos más comunes y más distribuidos, en especial de los artrópodos, en el interior de un bosque húmedo tropical primario.2. El trabajo se realizó en el valle medio del Río Magdalena, en una región a 150 m. s.n.m. con precipitaciones anuales entre 2 y 4 m. y temperaturas medias entre 28 y 29º C.3. Las colecciones se hicieron en dos tipos diferentes de bosque que son caracterizados por su vegetación. El tipo III tiene una capa de humus bruto de 5 - 20 cm. de grosor lo que es excepcional para bosques del tipo arriba señalado.4. Para las colecciones cuantitativas en los distintos estratos se utilizaron aparatos segun BERLESE/TULLGREN,red de insectos según REITTER, red de golpe, trampas según BARBER, redes finas de seda para aves y trampas de aire para artrópodos en diferentes niveles. Una parte esencial de este nuevo tipo de trampas de aire es la de tener vidrios planos inclinados que deben desviar insectos voladores hacia un vaso con formol.El número de insectos cogidos en esta manera es alto y permite una evaluación, por lo menos relativa, de la densidad de actividad en estas capas.5. Con los métodos mencionados en el punto 4. se cogieron unos 22.000 artrópodos, 86 aves y 9 murciélagos. Los' números de animales que coresponden a los distintos grupos sistemáticos (generalmente órdenes y a los distintos métodos de colección aparecen en las tablas Nos. 9-17.6. De los resultados obtenidos se añalizó a La magnitud absoluta. b La relación de abundancia y densidad de actividad entre los diferentes estratos, c La participación de los diferentes órdenes de animales en las colecciones. Un resumen de la discusión sobre la distribución de la fauna aparece en el capítulo "Conclusiones generales" (IV.d..

The microfauna assemblages as indicators of paleoenvironmental changes in the Miocene fluvial- lacustrine cycles (NE Duero Basin, Spain

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A. Herrero-Hernández

2016-11-01

Full Text Available The siliclastic and carbonate deposits are interbedded in the Villadiego area (Miocene, NE Duero Basin. They have been subdivided into two high-rank depositional sequences: DDS and CDS. The sedimentary analysis of these units and the study of the microfauna content, mainly ostracods, led to the identification of lacustrine-fluvial interaction systems. The sedimentary characteristics reveal the existence of fluvial systems of gravel, flood plains and lacustrine systems that were interconnected and intimately related in north-south direction. In the sedimentological analysis, thirteen types of fluvial and lacustrine lithofacies and six genetic facies associations were recognized. The top of DDS is the result of lake level risings. The CDS shows a deepening-shallowing cycle. The ostracod micropaleontological analysis of the sediments have been studied, with the aim of reconstructing the palaeoenvironmental evolution of this area. These microfauna assemblages integrated with the analysis of the sedimentary facies allowed to conclude the existence of lakes with a water-bearing level of few tens of meters. A change in the chemical conditions of the waters, which evolved from oligohaline and carbonated to mesohaline and sulphated is concluded.

Evidence for an early land use in the Rhône delta (Mediterranean France) as recorded by late Holocene fluvial paleoenvironments (1640-100 BC)

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Arnaud-Fassetta, Gilles; De Beaulieu, Jacques-Louis; Suc, Jean-Pierre; Provansal, Mireille; Williamson, David; Leveau, Philippe; Aloïsi, Jean-Claude; Gadel, François; Giresse, Pierre; Oberlin, Christine; Duzer, Danièle

The overall objective of this paper is to describe the late Holocene (1640-100 BC) sedimentary and biological evolution of the Rhône-delta-plain, to interpret the sedimentary facies and palynofacies as the result of the effects of fluvial dynamic fluctuations and relative sea level change and to evaluate the paleohydrological constraints in the development of the land use and settlements of the Camargue. Focus is made on the upper part of V III core drilled on NE of the Vaccarès lagoon. By combining sedimentology, palynology, magnetic susceptibility and archeological data, this study allowed to identify the superposition of three types of paleo-environments (marsh, fluvial floodplain, levee/crevasse splay). This sequence indicates a gradual extension of fluvial environments between the end of the second millennium BC and the 1st century BC. The variability of fluvial dynamic is evident during this period with important flood events which contrast with periods of low flow. Pollen record can be a good marker of the fluvial dynamic variability. The expression of the riparian tree pollen grains in the coarser floodplain deposits could correspond to increased fluvial influence and probably to erosion of riverbank during flood events. The local plants are associated to the low energy sedimentary environments. Focuses are made on the relations between the evolution of the environment and land use. The development of the cereal culture in the floodplain of the Rhône delta has been demonstrated between 1640-1410 and 100 BC. The last alluviation of the Rhône perturbs the research of the archaeological sites in the central part of the delta but the existence of the rural villages from the first part of the first millennium BC is highly possible.

Fluvial wood function downstream of beaver versus man-made dams in headwater streams in Massachusetts, USA

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David, G. C.; DeVito, L. F.; Munz, K. T.; Lisius, G.

2014-12-01

Fluvial wood is an essential component of stream ecosystems by providing habitat, increasing accumulation of organic matter, and increasing the processing of nutrients and other materials. However, years of channel alterations in Massachusetts have resulted in low wood loads despite the afforestation that has occurred since the early 1900s. Streams have also been impacted by a large density of dams, built during industrialization, and reduction of the beaver population. Beavers were reintroduced to Massachusetts in the 1940s and they have since migrated throughout the state. Beaver dams impound water, which traps sediment and results in the development of complex channel patterns and more ecologically productive and diverse habitats than those found adjacent to man-made dams. To develop better management practices for dam removal it is essential that we understand the geomorphic and ecologic function of wood in these channels and the interconnections with floodplain dynamics and stream water chemistry. We investigate the connections among fluvial wood, channel morphology, floodplain soil moisture dynamics, and stream water chemistry in six watersheds in Massachusetts that have been impacted by either beaver or man-made dams. We hypothesize that wood load will be significantly higher below beaver dams, subsequently altering channel morphology, water chemistry, and floodplain soil moisture. Reaches are surveyed up- and downstream of each type of dam to better understand the impact dams have on the fluvial system. Surveys include a longitudinal profile, paired with dissolved oxygen and ammonium measurements, cross-section and fluvial wood surveys, hydraulic measurements, and floodplain soil moisture mapping. We found that dissolved oxygen mirrored the channel morphology, but did not vary significantly between reaches. Wood loads were significantly larger downstream of beaver dams, which resulted in significant changes to the ammonium levels. Floodplain soil moisture

Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi)

Science.gov (United States)

Sheryl Coombs; Gary D. Grossman

2006-01-01

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities...

Calculation of paleohydraulic parameters of a fluvial system under spatially variable subsidence, of the Ericson sandstone, South western Wyoming

Science.gov (United States)

Snyder, H.; Leva-Lopez, J.

2017-12-01

During the late Campanian age in North America fluvial systems drained the highlands of the Sevier orogenic belt and travelled east towards the Western Interior Seaway. One of such systems deposited the Canyon Creek Member (CCM) of the Ericson Formation in south-western Wyoming. At this time the fluvial system was being partially controlled by laterally variable subsidence caused by incipient Laramide uplifts. These uplifts rather than real topographic features were only areas of reduced subsidence at the time of deposition of the CCM. Surface expression at that time must have been minimum, only minute changes in slope and accommodation. Outcrops around these Laramide structures, in particular both flanks of the Rock Springs Uplift, the western side of the Rawlins uplift and the north flank of the Uinta Mountains, have been sampled to study the petrography, grain size, roundness and sorting of the CCM, which along with the cross-bed thickness and bar thickness allowed calculation of the hydraulic parameters of the rivers that deposited the CCM. This study reveals how the fluvial system evolved and responded to the very small changes in subsidence and slope. Furthermore, the petrography will shed light on the provenance of these sandstones and on the relative importance of Sevier sources versus Laramide sources. This work is framed in a larger study that shows how incipient Laramide structural highs modified the behavior, style and architecture of the fluvial system, affecting its thickness, facies characteristics and net-to-gross both down-dip and along strike across the basin.

Detrital shadows: estuarine food web connectivity depends on fluvial influence and consumer feeding mode.

Science.gov (United States)

Howe, Emily; Simenstad, Charles A; Ogston, Andrea

2017-10-01

We measured the influence of landscape setting on estuarine food web connectivity in five macrotidal Pacific Northwest estuaries across a gradient of freshwater influence. We used stable isotopes (δ 13 C, δ 15 N, δ 34 S) in combination with a Bayesian mixing model to trace primary producer contributions to suspension- and deposit-feeding bivalve consumers (Mytilus trossulus and Macoma nasuta) transplanted into three estuarine vegetation zones: emergent marsh, mudflat, and eelgrass. Eelgrass includes both Japanese eelgrass (Zostera japonica) and native eelgrass (Zostera marina). Fluvial discharge and consumer feeding mode strongly influenced the strength and spatial scale of observed food web linkages, while season played a secondary role. Mussels displayed strong cross-ecosystem connectivity in all estuaries, with decreasing marine influence in the more fluvial estuaries. Mussel diets indicated homogenization of detrital sources within the water column of each estuary. In contrast, the diets of benthic deposit-feeding clams indicated stronger compartmentalization in food web connectivity, especially in the largest river delta where clam diets were trophically disconnected from marsh sources of detritus. This suggests detritus deposition is patchy across space, and less homogenous than the suspended detritus pool. In addition to fluvial setting, other estuary-specific environmental drivers, such as marsh area or particle transport speed, influenced the degree of food web linkages across space and time, often accounting for unexpected patterns in food web connectivity. Transformations of the estuarine landscape that alter river hydrology or availability of detritus sources can thus potentially disrupt natural food web connectivity at the landscape scale, especially for sedentary organisms, which cannot track their food sources through space. © 2017 by the Ecological Society of America.

Revisiting geochemical methods of distinguishing natural concentrations and pollution by risk elements in fluvial sediments

Czech Academy of Sciences Publication Activity Database

Matys Grygar, Tomáš; Popelka, J.

2016-01-01

Roč. 170, NOV (2016), s. 39-57 ISSN 0375-6742 R&D Projects: GA ČR(CZ) GA15-00340S Institutional support: RVO:61388980 Keywords : Enrichment * Fluvial sediments * Heavy metals Subject RIV: DD - Geochemistry Impact factor: 2.464, year: 2016

Dinámica temporal del NDVI del bosque y pastizal natural en el Chaco de la Provincia de Santiago del Estero, Argentina / The temporal dynamic of NDVI, of forest and grassland in the Chaco Seco of Santiago del Estero province, Argentine

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Hugo Raul Zerda

2010-04-01

Full Text Available Mediante imágenes mapas del índice de vegetación de diferencia normalizada (NDVI derivados del SPOT 4-Vegetation, se analizó la dinámica interanual y mensual de muestras de bosque nativo y pastizal natural de la provincia de Santiago del Estero, Argentina. Los resultados, muestran diferencias significativas (p pequenõs 0.05 para ambas coberturas, en la dinámica interanual y mensual. La actividad fotosintética del bosque se muestra superior a la del pastizal natural, analizada a partir de las curvas de NDVI. La dinámica del bosque y del pastizal natural, sigue el modelo regional de precipitaciones, alcanzando mayores valores de NDVI, durante la estación húmeda estival (Octubre-Mayo y menores valores de NDVI, durante la estación seca invernal (Junio-Septiembre. El bosque presentó mayor estabilidad que el pastizal natural, ante variaciones en las precipitaciones y temperatura, esperable por la mayor diversidad de especies en los bosques, y especialmente por las leñosas de raíces más profundas. La curva NDVI del pastizal natural, muestra sensibilidad al efecto de las elevadas intensidades de radiación en el verano, evapotranspiración y sequías; y debido a la mayor eficiencia del sistema radicular para el aprovechamiento del agua disponible, responde de manera inmediata ante las precipitaciones.AbstarctThe interannual and monthly dynamic of samples of forest and grassland from Santiago del Estero province, Argentine Republic, was analyzed through maps of vegetation of normalized difference (NDVI index derived from Vegetation/SPOT4 sensor. The results demonstrate that both covers, interannual and monthly dynamic mentioned before, have significant differences (p<0.05. The photosynthetic activity of the forest is superior compared with the one of the grassland, analyzed from the NDVI curves. The forest and the grassland dynamic, follows the regional precipitation pattern, reaching higher values from NDVI, during the summer humid

Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

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J. H. Nienhuis

2017-09-01

Full Text Available The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal dynamics or allogenic (external forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

Quantitative reconstruction of cross-sectional dimensions and hydrological parameters of gravelly fluvial channels developed in a forearc basin setting under a temperate climatic condition, central Japan

Science.gov (United States)

Shibata, Kenichiro; Adhiperdana, Billy G.; Ito, Makoto

2018-01-01

Reconstructions of the dimensions and hydrological features of ancient fluvial channels, such as bankfull depth, bankfull width, and water discharges, have used empirical equations developed from compiled data-sets, mainly from modern meandering rivers, in various tectonic and climatic settings. However, the application of the proposed empirical equations to an ancient fluvial succession should be carefully examined with respect to the tectonic and climatic settings of the objective deposits. In this study, we developed empirical relationships among the mean bankfull channel depth, bankfull channel depth, drainage area, bankfull channel width, mean discharge, and bankfull discharge using data from 24 observation sites of modern gravelly rivers in the Kanto region, central Japan. Some of the equations among these parameters are different from those proposed by previous studies. The discrepancies are considered to reflect tectonic and climatic settings of the present river systems, which are characterized by relatively steeper valley slope, active supply of volcaniclastic sediments, and seasonal precipitation in the Kanto region. The empirical relationships derived from the present study can be applied to modern and ancient gravelly fluvial channels with multiple and alternate bars, developed in convergent margin settings under a temperate climatic condition. The developed empirical equations were applied to a transgressive gravelly fluvial succession of the Paleogene Iwaki Formation, Northeast Japan as a case study. Stratigraphic thicknesses of bar deposits were used for estimation of the bankfull channel depth. In addition, some other geomorphological and hydrological parameters were calculated using the empirical equations developed by the present study. The results indicate that the Iwaki Formation fluvial deposits were formed by a fluvial system that was represented by the dimensions and discharges of channels similar to those of the middle to lower reaches of

External controls on Quaternary fluvial incision and terrace formation at the Segre River, Southern Pyrenees

NARCIS (Netherlands)

Stange, K.M.; van Balen, R.T.; Vandenberghe, J.; Peña, J.L.; Sancho, C.

2013-01-01

Focusing on climatic- and structural (tectonic) controls, we aim to determine their relative importance for the (Pliocene to Quaternary) fluvial landscape evolution in the Southern Pyrenees foreland. We investigate the Segre River, which is one of the major streams of the Southern Pyrenees that

Análisis del sitio de un bosque altoandino con énfasis en el mantillo. Microcuenca de la quebrada "La Vieja", Bogotá, Colombia

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Johanna Paola Vargas Núñez

2002-07-01

Full Text Available RESUMENLa materia orgánica es un compartimento importante dentro de los ecosistemas y su estudiopuede proporcionar criterios de manejo para ecosistemas con conflicto de uso, como son los Bos-ques Altoandinos en Colombia. Para realizar este estudio, se escogió un bosque altoandino en loscerros orientales de la ciudad de Bogotá. Para el sitio de estudio se caracterizaron las reservasorgánicas y minerales de los compartimentos foliar, mantillo y suelo; adicionalmente se establecióla descomposición mediante el método de canastas de descomposición de tres mantillos de dis-tintas procedencias (bosque altoandino de Bojacá, bosque de robles de Pacho y páramo de CruzVerde, además del mantillo del sitio, y de cuatro especies seleccionadas (Clusia multiflora, Piperbogotense, Juglans neotropicay Tillandsia fendleri. Las especies con mayor descomposición fueronJuglans neotropicay Piper bogotense, las cuales presentaron también los mayores contenidos denutrientes y la mayor liberación de nutrientes en la descomposición; Clusia multifloray Tillandsiafendleripresentaron menor descomposición y menores contenidos de nutrientes. C. multiflorapre-sentó una liberación media de nutrientes y T. fendleriuna liberación baja. Basándose en estascaracterísticas, se sugiere utilizar a J. neotropicay P. bogotense para la movilización de nutrientesdentro del sitio y a C. multiflorapara promover la reserva de nutrientes dentro del mantillo delbosque. El aporte desde el compartimento foliar al compartimento mantillo representado en lacaída de hojarasca fue de 13.4 Ton · Ha-1 · Año-1, siendo las especies que más aportan Clusiamultiflora, Vaccinumsp. y Weinmannia tomentosa. La profundidad promedio del mantillo fue de 16cm, con una densidad promedio de 14.32 Kg · m-3y un peso promedio de 23.49 Ton por hectárea.El mantillo proveniente de Bojacá y el mantillo nativo del sitio presentaron la mayor descom-posición, los mayores contenidos de nutrientes y

Arquitectura fluvial de las «Areniscas del río Arandilla». Triásico de Molina de Aragón (Guadalajara

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Sánchez-Moya, Y.

1989-08-01

Full Text Available The outstanding outcrops of Upper Buntsandstein sediments (Middle Triassic in Molina de Aragón (Guadalajara area, allow a detailed study of their characteristics and their associations which are described here. The fluvial architecture of the section indicates four main depositional episodes. The two lowest episodes were laid down by a fluvial system characterized by frequent channel shifting, low sinuosity and wide shallow channels. The drainage basin was controlled by highly seasonal discharge. The middle episode evolved into a more distal systems, with smaller higher sinuosity channels and fine overbank deposits. The uppermost episode is related to an increase of slope in the basin. That increase is probably related to tectonic movements recorded in this area. An attempt has been made to correlate the above events to the global sea level fluctuations (Haq et al., 1987. So, the low stage that have been stated occurred during Early Anisian can be tentatively correlated with the uppermost episode in Areniscas del río Arandilla.Los excelentes afloramientos de la parte superior del Buntsandstein (Triásico medio en Molina de Aragón (Guadalajara, han permitido llevar a cabo un análisis sedimentológico detallado de las facies fluviales y de su arquitectura. Se han distinguido doce diferentes facies cuyas características y asociaciones se describen en este trabajo. La evolución fluvial indica la existencia de cuatro episodios deposicionales. Los dos episodios inferiores son característicos de un sistema fluvial con canales de baja sinuosidad, inestables, de gran amplitud y poca profundidad. El drenaje de la cuenca estaba controlado por importantes descargas estacionales. El episodio intermedio es el resultado de la evolución del sistema hacia facies más distales. En esta etapa los canales son de menor tamaño, la sinuosidad es mayor y existe un mayor porcentaje de depósitos de granulometría fina relacionados con la llanura de inundaci

Participative restoration of the monument national Bosque de Piedra Isabel Rubio

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Barbarita Mijans Moreno

2013-06-01

Full Text Available The work was carried out in four hectares of the «Monument National» Bosque Piedra Isabel Rubio, belonging to the Forest Company Macurije municipality Guane. Ecosystem that possesses national significance because it constitutes a valuable monumental example, it summarizes natural aspects as their calcareous formations of the Jurassic period, besides their intangible values associated to the rural traditions. The objective of the research is to propose a plan of action participative for the restoration of this ecosystem starting from the results obtained in diagnose participative. Among the used scientific methods, they are the research Action Participative and the participant observation, for the collection of information the interview was used in depth, and the meetings in groups. As important results the presence of a strong pressure antropic is obtained on the flora, fauna and rocks of the minimogotes, the introduction of exotic and invasive species, and soil erosion, in consequence the degradation of the ecosystem and loss of the biodiversity. Another significant result constituted it the scarce level of the actors' knowledge regarding the category of this forest and the administrative juridical regulations that govern it. The removed evidences of these communities show that the necessity to diminish the antropics actions and to elevate the sensibility regarding the conservation, they impose a demand of knowledge to satisfy by means of training actions with the participation of the local actors and instrumentation of the regulative apparatus.

DINÁMICA DE LA BIOMASA AÉREA EN UN BOSQUE PLUVIAL TROPICAL DEL CHOCÓ BIOGEOGRÁFICO DYNAMICS OF TREE ABOVEGROUND BIOMASS IN A TROPICAL RAIN FOREST OF THE CHOCÓ BIOGEOGRÁFICO

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Harley Quinto Mosquera

2011-06-01

Full Text Available El estudio de la biomasa aérea (BA de los bosques tropicales es fundamental para entender el balance del C global en el contexto del cambio climático. La BA se cuantificó en un bosque maduro de Salero (Chocó Biogeográfico, mediante ecuaciones diseñadas para bosques húmedos tropicales, a partir de datos de densidad de madera, diámetro (DAP y altura de árboles (con DAP = 10 cm medidos en dos sub-parcelas permanentes ("E" y "U" de 1 ha, las cuales se monitorearon en los años 1998, 2005 y 2008. La BA fue 237,31 t·ha-1, 259,99 t·ha-1 y 217,97 t·ha-1 respectivamente en la sub-parcela "E". Mientras que en la "U" fue de 178,94 t·ha-1y 179,17 t·ha-1 en los años 2005 y 2008; las diferencias de BA a través del tiempo fueron no significativas. Los incrementos promedios anuales de BA de sobrevivientes fueron 4,42 y 3,18 t·ha-1 año-1 en las sub-parcelas "E" y "U" respectivamente. Además, en sub-parcela "E" en condiciones imperturbadas, se presentó una tasa de incremento neto de la BA (TINBA de 2,61 t·ha-1 año-1, en concordancia con la hipótesis del incremento en la BA en los bosques húmedos tropicales. La productividad primaria neta aérea (PPNA en Salero de carbono fue de 5,21 t· ha-1 año-1, por lo tanto los resultados no apoyaron la hipótesis de la disminución en la productividad de los bosques tropicales con el incremento en la precipitación.The study of the aboveground biomass (AB of tropical forests is fundamental to understand the balance of the global C in the context of the climatic change. We quantified the AB in a mature forest of Salero (Chocó Biogeográfico, by means of equations designed for tropical humid forests, starting from data of wooden density, diameter (D and height of trees (with D = 10 cm measured in two permanent sub-parcels (E and U of 1 hectare (ha, which were measured in the years 1998, 2005 and 2008. Inthis years the AB was of 237.31 t·ha-1, 259.99 t·ha-1 and 217.97 t·ha-1 respectively in the E

Pemaknaan Filsafati Kearifan Lokal untuk Adaptasi Masyarakat terhadap Ancaman Bencana Marin dan Fluvial di Lingkungan Kepesisiran

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S Sunarto

2011-07-01

Full Text Available The purpose of this research was to study the philosophical meaning of local wisdom that developed in the communities in the coastal environment, particularly in the eastern coast of Central Java. The method used for this philosophical meaning using the approach of geomorphological hermeneutics and disaster semiotics. The results of this research indicate that identified local wisdom in the form of cultural semiotics and faunal semiotics to anticipate the hazards of climate change as marine hazard and fluvial hazard. Cultural semiotics found in the form of advice that still need to be interpreted with a geomorphological hermeneutics approach order to use it to adapt to the coastal environment against marine hazard. The cultural semiotics has a geomorphological philosophical meaning as natural cycle that leads to dynamic equilibrium, not the philosophical meaning that leads to the view of anthropocentrism. In addition, also found cultural semiotics of “Dina Rèntèng” based on the philosophical views of ecocentrism. The cultural semiotics is used in society to adapt to the fluvial hazard. Faunal semiotics found in the form of anomalous crab behavior as a form of adaptation due to its response to environmental condition. The faunal semiotics has been used as a guide for the community to adapt to the fluvial hazard. Because of the local wisdom is loaded with philosophical meaning, it can be metatourism assets, so it can convert harm into benefit.

Efecto del manejo forestal en la diversidad y composición arbórea de un bosque templado del noroeste de México

OpenAIRE

Hernández-Salas, Javier; Aguirre-Calderón, Óscar A.; Alanís-Rodríguez, Eduardo; Jiménez-Pérez, Javier; Treviño-Garza, Eduardo J.; González-Tagle, Marco A.; Luján-Álvarez, Concepción; Olivas-García, Jesús M.; Domínguez-Pereda, Alfonso

2013-01-01

En la presente investigación se evaluó el efecto de las prácticas silvícolas en la diversidad y composición de especies arbóreas de un bosque templado del noroeste de México. Para ello, 46 parcelas fueron evaluadas cada 10 años: 1986, 1996 y 2006. Se estimaron los índices de diversidad alfa y beta de la comunidad arbórea, y la abundancia, dominancia, frecuencia e índice de valor de importancia de cada especie (IVI). Los resultados muestran que el aprovechamiento forestal modifica la diversida...

Gestión integrada de los recursos hídricos y bosques nativos de la cuenca del arroyo Feliciano, Entre Ríos, Argentina

OpenAIRE

Romero, Emilia Corina

2013-01-01

[Resumen] El área de estudio comprende la cuenca del Arroyo Feliciano, la segunda en extensión de la Provincia de Entre Ríos, con 8199 km2. Cuenta con una demanda creciente de sus recursos hídricos por la intensa agriculturización, con cambio repentino en el uso del suelo, pasando de una ganadería extensiva y bajo bosque natural, al uso arrocero - sojero. Los acuíferos presentes en casi la totalidad de su superficie son de baja aptitud físico-química, lo que genera inconvenientes a la poblaci...

Geoarchaeology, the four dimensional (4D) fluvial matrix and climatic causality

Science.gov (United States)

Brown, A. G.

2008-10-01

Geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales. Geoarchaeology in the UK over the last twenty years has flourished largely because it has gone beyond technological and scientific applications. Over the same period our ability to reconstruct the 3-dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances. These have included the use of LiDAR (laser imaging) and radar to produce high-resolution digital surface models, the use of geophysics, particularly ground penetrating radar and electrical resistivity, to produce sediment depth models, and the use of GIS and data visualisation techniques to manipulate and display the data. These techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3-dimensional (volumetric) models of the matrix of artefacts within fluvial deposits. Additionally a revolution in dating techniques, particularly direct sediment dating by luminescence methods, has enabled the creation of 4-dimensional models of the creation and preservation of these sites. These 4-dimensional models have the ability to provide far more information about the processes of site creation, preservation and even destruction, and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change. All improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales. This allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level. This data can then form a component of

Allogenic controls on the fluvial architecture and fossil preservation of the Upper Triassic Ischigualasto Formation, NW Argentina

Science.gov (United States)

Colombi, Carina E.; Limarino, Carlos O.; Alcober, Oscar A.

2017-12-01

The Upper Triassic Ischigualasto Formation in NW Argentina was deposited in a fluvial system during the synrift filling of the extensional Ischigualasto-Villa Unión Basin. The expansive exposures of the fluvial architecture and paleosols provide a framework to reconstruct the paleoenvironmental evolution of this basin during the Upper Triassic using continental sequence stratigraphy. The Ischigualasto Formation deposition can be divided into seven sequential sedimentary stages: the 1) Bypass stage; 2) Confined low-accommodation stage; 3) Confined high accommodation stage; 4) Unstable-accommodation stage; 5) Unconfined high-accommodation stage; 6) Unconfined low-accommodation stage; and finally, 7) Unconfined high-accommodation stage. The sedimentary evolution of the Ischigualasto Formation was driven by different allogenic controls such as rises and falls in lake levels, local tectonism, subsidence, volcanism, and climate, which also produced modifications of the equilibrium profile of the fluvial systems. All of these factors result in different accommodations in central and flank areas of the basin, which led to different architectural configurations of channels and floodplains. Allogenic processes affected not only the sequence stratigraphy of the basin but also the vertebrate and plant taphocenosis. Therefore, the sequence stratigraphy can be used not only as a predictive tool related to fossil occurrence but also to understand the taphonomic history of the basin at each temporal interval.

Avulsion and its implications for fluvial-deltaic architecture: insights from the Holocene Rhine-Meuse delta

NARCIS (Netherlands)

Stouthamer, E.; Cohen, K.M.; Gouw, M.J.P.

2010-01-01

Avulsion is a key process in the formation of fluvial-deltaic successions and a primary control on deltaic architecture. It determines the distribution of sediment and water and hence which location in the delta receives clastic sedimentation for what time. This makes the avulsion process an

Avulsion and its implications for fluvial-deltaic architecture: insights from the Holocene Rhine-Meuse delta

NARCIS (Netherlands)

Stouthamer, E.; Cohen, K.M.; Gouw, M.J.P.

2010-01-01

Avulsion is a principal process in the formation of fluvial-deltaic successions and a primary control on deltaic architecture. It determines the distribution of sediment and water and hence influences which location in the delta receives clastic sedimentation in what amounts for what time. It also

La importancia del bosque en la recarga hídrica natural del acuífero noreste de la ciudad de Guatemala

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isaac rodolfo herrera ibañez

2016-08-01

Full Text Available En la región volcánica con superficie boscosa la recarga natural es importante, debido a ello, este trabajo pretende realizar un análisis sobre el cálculo de la recarga en estas áreas. La investigación fue ejecutada en la cuenca del río Los Ocotes en la ciudad de Guatemala y cubre una superficie aproximada de 64 km2. En este trabajo se realizó un balance hídrico del suelo, donde el agua se mueve a través del perfil de suelo y descarga en el sistema superficial o bien como flujo base. Existen un conjunto de procedimientos para estimar la distribución entre las entradas como precipitación y las salidas a través de la evapotranspiración, el escurrimiento superficial y la recarga subterránea. En 2009 y 2010 se llevaron registros meteorológicos y se definieron áreas con distinto uso de la tierra, lo cual se integro a un sistema de información geográfica (SIG y se comparo con el mapa geomorfológico a escala 1:50,000 para elaborar el mapa de recarga de la cuenca con los datos calculados. Los sectores cultivados mostraron una menor infiltración y por lo tanto una menor recarga que en los sectores donde el bosque se encuentra en estado natural. La protección de las zonas de bosque como principal área de aporte a las reservas de agua subterránea, representa un aspecto fundamental para los procesos de gestión y planificación territorial. Palabras clave: Balance, suelo, precipitación, evapotranspiración, infiltración

Evolution of tertiary intermontane fluvial system of Powder River Basin, Wyoming and Montana

International Nuclear Information System (INIS)

Flores, R.M.; Ethridge, F.G.

1985-01-01

Exploration and development of economic coal and uranium deposits of the Tertiary Fort Union and Wasatch Formations provided data related to the evolution of depositional systems in the Powder River Basin. In ascending order, the Paleocene Fort Union Formation consists of the Tullock, Lebo, and Tongue River Members. The overlying Eocene Wasatch Formation consists of the conglomeratic Kingsbury and Moncrief Members and laterally equivalent finer grained deposits. Evolution of fluvial deposition in the basin was determined from sandstone percent maps. A high proportion of sandstones in the Tullock Member and combined Tongue River Member and Wasatch Formation formed in interconnected east-west and north-south belts. The east-west belts represent alluvial fans, as well as braided and meandering tributary streams. The north-south belts reflect meandering and anastomosing trunk streams fed by basin margin tributaries. The sandstones of the Lebo Shale show east-west trends and represent deposits of fluvio-deltaic systems that filled a western, closed-lacustrine basin. The lake in this basin may have formed during localized subsidence along the Buffalo deep fault. These contrasting styles of fluvial deposition were largely controlled by extrabasinal and intrabasinal tectonics associated with Laramide orogeny

Distribution of uranium and thorium in sediments and plants from a granitic fluvial area

International Nuclear Information System (INIS)

Vargas, M.J.; Tome, F.V.; Sanchez, A.M.; Vazquez, M.T.C.; Murillo, J.L.G.

1997-01-01

A study of the presence of natural uranium and thorium isotopes in sediments and plants belonging to a granitic fluvial region of the Ortigas river (west of Spain) has been carried out. The existence of two uranium mines in the neighbourhood of the sampled sites and the granitic characteristics of the zone produce significant concentrations of natural radionuclides. Temporal and spatial variations of uranium and thorium concentrations and the activity ratios 234 U/ 238 U, 228 Th/ 232 Th and Th/U were studied to better understand the mobilization mechanisms such as leaching and transport at play in the studied system. These determinations were made using alpha-particle spectrometry with silicon detectors. The measurements were also compared with the results previously found for waters of this fluvial area. Uranium in sediments showed variations due to changes in rainfall, but thorium content was nearly constant. Uranium and thorium concentrations in plants were lower after rainfall. Incorporation of uranium into the plants seemed to be mainly from water, whereas incorporation of thorium seemed to be from both sediments and water. (Author)

Modelling sediment dynamics due to hillslope-river interactions : incorporating fluvial behaviour in landscape evolution model LAPSUS

NARCIS (Netherlands)

Baartman, Jantiene E. M.; van Gorp, Wouter; Temme, Arnaud J. A. M.; Schoorl, Jeroen M.

Landscape evolution models (LEMs) simulate the three-dimensional development of landscapes over time. Different LEMs have different foci, e.g. erosional behaviour, river dynamics, the fluvial domain, hillslopes or a combination. LEM LAPSUS is a relatively simple cellular model operating on

Patrones de diversidad de aves a lo largo de un gradiente latitudinal de bosques ribereños del río Paraná medio, Argentina

OpenAIRE

Berduc, Alfredo; Lorenzón, Rodrigo Ezequiel; Beltzer, Adolfo Héctor

2015-01-01

Se estudió la variación de la riqueza de especies (diversidad alfa), la diversidad beta, la abundancia y la equidad de ensambles de aves a lo largo de un gradiente latitudinal de 500 km de bosques ribereños. Se muestrearon 5 localidades ubicadas en dirección norte-sur mediante una técnica mixta: transectos y puntos de conteo. La riqueza de especies decreció con el incremento de la latitud, reproduciendo el patrón de la riqueza regional informado en estudios previos. Los resultados apoyaron la...

Fluvial fluxes from the Magdalena River into Cartagena Bay, Caribbean Colombia: Trends, future scenarios, and connections with upstream human impacts

Science.gov (United States)

Restrepo, Juan D.; Escobar, Rogger; Tosic, Marko

2018-02-01

Fluxes of continental runoff and sediments as well as downstream deposition of eroded soils have severely altered the structure and function of fluvial and deltaic-estuarine ecosystems. The Magdalena River, the main contributor of continental fluxes into the Caribbean Sea, delivers important amounts of water and sediments into Cartagena Bay, a major estuarine system in northern Colombia. Until now, trends in fluvial fluxes into the bay, as well as the relationship between these tendencies in fluvial inputs and associated upstream changes in the Magdalena catchment, have not been studied. Here we explore the interannual trends of water discharge and sediment load flowing from the Magdalena River-Canal del Dique system into Cartagena Bay during the last three decades, forecast future scenarios of fluxes into the bay, and discuss possible connections between observed trends in fluvial inputs and trends in human intervention in the Magdalena River basin. Significant upward trends in annual runoff and sediment load during the mid-1980s, 1990s, and post-2000 are observed in the Magdalena and in the Canal del Dique flowing into Cartagena Bay. During the last decade, Magdalena streamflow and sediment load experienced increases of 24% and 33%, respectively, compared to the pre-2000 year period. Meanwhile, the Canal del Dique witnessed increases in water discharge and sediment load of 28% and 48%, respectively. During 26 y of monitoring, the Canal del Dique has discharged 177 Mt of sediment to the coastal zone, of which 52 Mt was discharged into Cartagena Bay. Currently, the Canal drains 6.5% and transports 5.1% of the Magdalena water discharge and sediment load. By 2020, water discharge and sediment flux from the Canal del Dique flowing to the coastal zone will witness increments of 164% and 260%, respectively. Consequently, sediment fluxes into Cartagena Bay will witness increments as high as 8.2 Mt y- 1 or 317%. Further analyses of upstream sediment load series for 21

Estuary-wide genetic stock distribution and salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

The phosphorus content of fluvial sediment in rural and industrialized river basins.

Science.gov (United States)

Owens, Philip N; Walling, Desmond E

2002-02-01

The phosphorus content of fluvial sediment (suspended sediment and the sediment) has been examined in contrasting rural (moorland and agricultural) and industrialized catchments in Yorkshire, UK. The River Swale drains a rural catchment with no major urban and industrial areas, and the total phosphorus (TP) content of fluvial sediment is generally within the range 500-1,500 microg g(-1). There is little evidence of any major downstream increase in TP content. In contrast, fluvial sediment from the industrialized catchments of the Rivers Aire and Calder exhibits both higher levels of TP content and marked downstream increases, with values of TP content ranging from 7,000 microg g(-1) at downstream sites. These elevated levels reflect P inputs from point sources, such as sewage treatment works (STWs) and combined sewer overflows. The influence of STWs is further demonstrated by the downstream increase in the inorganic P/organic P ratio from 4 in the lower reaches. Comparison of the P content of suspended sediment with that of the sediment and both discharge and suspended sediment concentration, reflecting changes in sediment and P sources during high flow events. Spatial variations in the P contents of the sediment evidence a similar pattern as those for suspended sediment, with relatively low levels of TP in the River Swale and elevated levels in the middle and downstream reaches of the Rivers Aire and Calder. The PP concentrations associated with floodplain and channel bed sediment are, however, lower than equivalent values for suspended sediment, and this primarily reflects the differences in the particle size composition between the three types of sediments. Rates of floodplain deposition and the amounts of fine-grained sediment stored in the river channels are relatively high, and suggest that such environments may represent important sinks for PP. Based on the sediment samples collected from the study basins, a simple four-fold classification which relates the

Variabilidad fenológica del bosque y del pastizal nativo en el Chaco Semiárido de la Provincia de Santiago del Estero, Argentina / Phenological variability of forest and native pastures in the Semiarid Chaco of the Santiago del Estero Province

Directory of Open Access Journals (Sweden)

Jose Luis Tiedermann

2012-04-01

Full Text Available ResumoLos parámetros estacionales del bosque y pastizal nativo del Chaco semiárido de Santiago del Estero fueron extractados a partir de series temporales del índice de vegetación NDVI derivadas del satélite SPOT VEGETATION, mediante el programa TIMESAT. El inicio y el fin de las estaciones de crecimiento del bosque en el período seco, presentaron un mínimo desplazamiento con respecto a las estaciones de crecimiento del período húmedo. Este desplazamiento estaría relacionado con la respuesta de las especies que conforman el estrato inferior y medio del bosque ante la variación de las precipitaciones entre períodos. El inicio y fin de las estaciones de crecimiento del pastizal nativo no presentaron variaciones temporales entre períodos. Esta respuesta estaría relacionada con la gran adaptación de esta cobertura a las adversidades climáticas extremas como las sequías. Los puntos medios y el NDVI máximo de las estaciones de crecimiento del bosque y del pastizal nativo, coinciden temporalmente con el otoño, esta respuesta estaría relacionada con una mayor efectividad de las precipitaciones, y con una menor evapotranspiración y temperatura. La producción total integrada y la productividad estacionalmente activa de las estaciones de crecimiento del bosque y del pastizal nativo, no fueron afectadas por el período. La estabilidad del bosque estaría relacionada con su biodiversidad, con su estructura estratificada, y por las especies leñosas de porte y raíces profundas que lo conforman; mientras que la estabilidad del pastizal nativo estaría relacionada con sus estratégicas adaptaciones, morfológicas, fisiológicas y de comportamiento para el uso eficiente del agua.AbstractThe seasonal parameters of the forest and native pasture of the semi-arid Chaco of Santiago del Estero were abstracted from temporary series of the vegetation index NDVI derived from satellite SPOT VEGETATION using the software TIMESAT. The beginning and

The Pliocene initiation and Early Pleistocene volcanic disruption of the palaeo-Gediz fluvial system, Western Turkey

NARCIS (Netherlands)

Maddy, D.; Demir, T.; Bridgland, D.R.; Veldkamp, A.; Stemerdink, C.; Schriek, van der T.; Schreve, D.

2007-01-01

In this paper, we report our latest observations concerning a Pliocene and Early Pleistocene record from Western Turkey. The sedimentary sequence described comprises the fluvial deposits of an Early Pleistocene palaeo-Gediz river system and its tributaries prior to the onset of volcanism around Kula

Buried late Pleistocene fluvial channels on the inner continental shelf off Vengurla, west coast of India

Digital Repository Service at National Institute of Oceanography (India)

SubbaRaju, L.V.; Krishna, K.S.; Chaubey, A.K.

with sediments. Cross sectional dimensions between 15 to 100 m width and 2 to 6 m depth suggest a fluvial origin of the channels. These buried channels appear to mark former positions of rivers flowing from the nearby coast and debouching into the Arabian Sea...

Estuarine abandoned channel sedimentation rates record peak fluvial discharge magnitudes

Science.gov (United States)

Gray, A. B.; Pasternack, G. B.; Watson, E. B.

2018-04-01

Fluvial sediment deposits can provide useful records of integrated watershed expressions including flood event magnitudes. However, floodplain and estuarine sediment deposits evolve through the interaction of watershed/marine sediment supply and transport characteristics with the local depositional environment. Thus extraction of watershed scale signals depends upon accounting for local scale effects on sediment deposition rates and character. This study presents an examination of the balance of fluvial sediment dynamics and local scale hydro-geomorphic controls on alluviation of an abandoned channel in the Salinas River Lagoon, CA. A set of three sediment cores contained discrete flood deposits that corresponded to the largest flood events over the period of accretion from 1969 to 2007. Sedimentation rates scaled with peak flood discharge and event scale sediment flux, but were not influenced by longer scale hydro-meteorological activities such as annual precipitation and water yield. Furthermore, the particle size distributions of flood deposits showed no relationship to event magnitudes. Both the responsiveness of sedimentation and unresponsiveness of particle size distributions to hydro-sedimentological event magnitudes appear to be controlled by aspects of local geomorphology that influence the connectivity of the abandoned channel to the Salinas River mainstem. Well-developed upstream plug bar formation precluded the entrainment of coarser bedload into the abandoned channel, while Salinas River mouth conditions (open/closed) in conjunction with tidal and storm surge conditions may play a role in influencing the delivery of coarser suspended load fractions. Channel adjacent sediment deposition can be valuable records of hydro-meteorological and sedimentological regimes, but local depositional settings may dominate the character of short term (interdecadal) signatures.

Impact of phenomenological theory of turbulence on pragmatic approach to fluvial hydraulics

Science.gov (United States)

Ali, Sk Zeeshan; Dey, Subhasish

2018-04-01

The phenomenological theory of turbulence (PTT) remains a long-standing and fascinating theory in turbulence research. In this review article, we highlight the state-of-the-science of the impact of the PTT on the pragmatic approach to fluvial hydraulics, explored over recent decades, discussing the salient and the subtle roles that the turbulence plays in governing many physical processes. To acquire a theoretical explanation of this pragmatic approach necessitates an intuitive thought that can bring together the background mechanisms of all the physical processes under one law—a thought that is capable of finding their inextricable links with the turbulent energy spectrum. We begin here with emphasizing the spectral and the co-spectral origin of the well-recognized laws of the wall, the resistance equation, and the turbulence intensities by portraying the typical momentum transfer mechanism of eddies in a turbulent flow. Next, we focus on the scaling laws of key fluvial processes derived from the perspective of the PTT, enlightening their physical insight and ability to judge how far the so-called empirical formulas can be used with confidence. The PTT has been able to disclose the origin of several primeval empirical formulas that have been used over many years without having any theoretical clarification and confirmation. Finally, we make an effort to describe some unsolved issues to be resolved as a future scope of research.

Human impact on fluvial regimes and sediment flux during the Holocene: review and future research agenda

NARCIS (Netherlands)

Hoffmann, T.; Thorndycraft, V.R.; Brown, A.G.; Coulthard, T.J.; Damnati, B.; Kale, V.S.; Middelkoop, H.; Notebaert, B.; Walling, D.E.

2010-01-01

There is a long history of human–riverine interactions throughout the period of agriculture that in some regions of the world started several thousand years ago. These interactions have altered rivers to human dominated systems with often negative impacts on fluvial environments. To achieve a good

Depositional record of an avulsive fluvial system controlled by peat compaction (Neogene, Most Basin, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Rajchl, M.; Uličný, David

2005-01-01

Roč. 52, č. 3 (2005), s. 601-625 ISSN 0037-0746 R&D Projects: GA ČR GA205/01/0629 Institutional research plan: CEZ:AV0Z30120515 Keywords : avulsion * Eger Graben * fluvial channels Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.876, year: 2005

A conceptual connectivity framework for understanding geomorphic change in human-impacted fluvial systems

Science.gov (United States)

Pöppl, Ronald; Keesstra, Saskia; Maroulis, Jerry

2017-04-01

Human-induced landscape change is difficult to predict due to the complexity inherent in both geomorphic and social systems as well as due to emerging coupling relationships between them. To better understand system complexity and system response to change, connectivity has become an important research paradigm within various disciplines including geomorphology, hydrology and ecology. With the proposed conceptual connectivity framework on geomorphic change in human-impacted fluvial systems a cautionary note is flagged regarding the need (i) to include and to systematically conceptualise the role of different types of human agency in altering connectivity relationships in geomorphic systems and (ii) to integrate notions of human-environment interactions to connectivity concepts in geomorphology to better explain causes and trajectories of landscape change. Underpinned by case study examples, the presented conceptual framework is able to explain how geomorphic response of fluvial systems to human disturbance is determined by system-specific boundary conditions (incl. system history, related legacy effects and lag times), vegetation dynamics and human-induced functional relationships (i.e. feedback mechanisms) between the different spatial dimensions of connectivity. It is further demonstrated how changes in social systems can trigger a process-response feedback loop between social and geomorphic systems that further governs the trajectory of landscape change in coupled human-geomorphic systems.

MODELLING LANDSCAPE MORPHODYNAMICS BY TERRESTRIAL PHOTOGRAMMETRY: AN APPLICATION TO BEACH AND FLUVIAL SYSTEMS

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E. Sánchez-García

2016-06-01

Full Text Available Beach and fluvial systems are highly dynamic environments, being constantly modified by the action of different natural and anthropic phenomena. To understand their behaviour and to support a sustainable management of these fragile environments, it is very important to have access to cost-effective tools. These methods should be supported on cutting-edge technologies that allow monitoring the dynamics of the natural systems with high periodicity and repeatability at different temporal and spatial scales instead the tedious and expensive field-work that has been carried out up to date. The work herein presented analyses the potential of terrestrial photogrammetry to describe beach morphology. Data processing and generation of high resolution 3D point clouds and derived DEMs is supported by the commercial Agisoft PhotoScan. Model validation is done by comparison of the differences in the elevation among the photogrammetric point cloud and the GPS data along different beach profiles. Results obtained denote the potential that the photogrammetry 3D modelling has to monitor morphological changes and natural events getting differences between 6 and 25 cm. Furthermore, the usefulness of these techniques to control the layout of a fluvial system is tested by the performance of some modeling essays in a hydraulic pilot channel.

Efectos del fósforo y carbono lábiles en la fijación no simbiótica de N2 en hojarasca de bosques siempreverdes manejados y no manejados de la Isla de Chiloé, Chile Effects of labile phosphorous and carbón on non-symbiotic N2 fixation in logged and unlogged evergreen forests in Chiloé Island, Chile

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SANDRA E PÉREZ

2008-06-01

Full Text Available El flujo de entrada de nitrógeno (N en ecosistemas de bosques templados de la Isla de Chiloé puede ocurrir en una proporción importante vía fijación no simbiótica (FNS. Debido a que este proceso es llevado a cabo por bacterias (diazótrofas está regulado, además del efecto de factores climáticos (temperatura y humedad, por la disponibilidad de nutrientes, en particular fósforo y carbono como fuentes de energía. Nuestra hipótesis es que si el fósforo y el carbono son limitantes para la FNS, esta limitación se acentuaría en bosques manejados, en donde adición experimental de P y C deberían estimular la actividad microbiana. En este trabajo se determinó los efectos de la adición de cuatro niveles de fósforo inorgánico (0 mmol P/L, 0,645 mmol P/L, 3,23 mmol P/L y 6,45 mmol P/L y cuatro niveles de carbono lábil como glucosa (0 mmol P/L, 23,3 mmol C/L, 46,6 mmol C/L y 70 mmol C/L, en la FNS de N2 de hojarasca homogenizada de cada bosque, en condiciones controladas de temperatura y humedad, en experimentos de laboratorio. Se estudiaron bosques de zonas bajas (100-200 m de altitud ubicados en la comuna de Chonchi, Isla de Chiloé. De estos bosques, dos habían sido manejados, uno por corta selectiva y otro por floreo, y el tercero (control era un bosque antiguo no intervenido. La FNS del nitrógeno se estimó mediante la "técnica de reducción de acetileno". Análisis de varianzas de dos vías mostraron que las adiciones de fósforo no afectaron en forma significativa las tasas de reducción de acetileno (TRA de la hojarasca en ninguno de los tres bosques, pero la adición de carbono lábil en forma de glucosa afectó negativamente la TRA en el máximo nivel aplicado, en la hojarasca del bosque no manejado. Solo el factor bosque, relacionado a la práctica silvicultural, dio cuenta de las diferencias observadas en las TRA, siendo mayores en el bosque no manejado. Estas diferencias no fueron explicadas por las variables manipuladas

Uso de la leña y conservación del bosque en el volcán Huitepec, Chiapas, México

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Arelí Santos González

2012-01-01

Full Text Available Se analiza la dinámica de uso de leña en ocho colonias alrededor del volcán Huitepec, Chiapas, aledañas a dos áreas naturales protegidas de manejo privado (Reserva Huitepec- Pronatura y colectivo (Reserva Zapatista, así como a una población urbana creciente: San Cristóbal de las Casas. En la zona de estudio es evidente la preocupación de conservar el bosque, sus recursos naturales y servicios ambientales fundamentales. De acuerdo al uso y manejo de la leña, se tipificaron a las colonias en cuatro categorías: atención prioritaria, atención básica, atención significativa y atención media.

On the connectivity anisotropy in fluvial Hot Sedimentary Aquifers and its influence on geothermal doublet performance

DEFF Research Database (Denmark)

Willems, Cees J.L.; Nick, Hamid; Donselaar, Marinus E.

2017-01-01

This study finds that the geothermal doublet layout with respect to the paleo flow direction in fluvial sedimentary reservoirs could significantly affect pump energy losses. These losses can be reduced by up to 10% if a doublet well pair is oriented parallel to the paleo flow trend compared...

Fluvial response to Holocene volcanic damming and breaching in the Gediz and Geren rivers, western Turkey

NARCIS (Netherlands)

van Gorp, W.; Veldkamp, A.; Temme, A.J.A.M.; Maddy, D; Demir, T.; Schriek van der, T.; Reimann, T.; Wallinga, J.; Wijbrans, J.R.; Schoorl, J.M.

2013-01-01

This study discusses the complex late Holocene evolution of the Gediz River north of Kula, western Turkey, when a basaltic lava flow dammed and filled this river valley. Age control was obtained using established and novel feldspar luminescence techniques on fluvial sands below and on top of the

Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary.

Science.gov (United States)

Foreman, Brady Z; Heller, Paul L; Clementz, Mark T

2012-11-01

Climate strongly affects the production of sediment from mountain catchments as well as its transport and deposition within adjacent sedimentary basins. However, identifying climatic influences on basin stratigraphy is complicated by nonlinearities, feedback loops, lag times, buffering and convergence among processes within the sediment routeing system. The Palaeocene/Eocene thermal maximum (PETM) arguably represents the most abrupt and dramatic instance of global warming in the Cenozoic era and has been proposed to be a geologic analogue for anthropogenic climate change. Here we evaluate the fluvial response in western Colorado to the PETM. Concomitant with the carbon isotope excursion marking the PETM we document a basin-wide shift to thick, multistoried, sheets of sandstone characterized by variable channel dimensions, dominance of upper flow regime sedimentary structures, and prevalent crevasse splay deposits. This progradation of coarse-grained lithofacies matches model predictions for rapid increases in sediment flux and discharge, instigated by regional vegetation overturn and enhanced monsoon precipitation. Yet the change in fluvial deposition persisted long after the approximately 200,000-year-long PETM with its increased carbon dioxide levels in the atmosphere, emphasizing the strong role the protracted transmission of catchment responses to distant depositional systems has in constructing large-scale basin stratigraphy. Our results, combined with evidence for increased dissolved loads and terrestrial clay export to world oceans, indicate that the transient hyper-greenhouse climate of the PETM may represent a major geomorphic 'system-clearing event', involving a global mobilization of dissolved and solid sediment loads on Earth's surface.

COMUNIDADES DE PALMAS EN DOS BOSQUES DE CHOCÓ, COLOMBIA

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Ramirez G

2011-12-01

Full Text Available Estudiamos la riqueza, la abundancia, la composición y la estructura de las comunidades de palmas en dos sitios de la selva central del Chocó, Colombia. Se establecieron 14 transectos (1.5 ha en Tutunendo y 12 transectos (1 ha en Angostura, y en cada uno se registraron e identificaron las palmas, incluyendo todos los tamaños (plántulas, juveniles y adultos; además, se indagó sobre nombres comunes y usos de cada especie, entrevistando a 16 hombres mayores de 45 años y conocedores del bosque. La riqueza de palmas encontrada en las localidades estudiadas (29 especies en 1.5 ha y 23 especies en 1 ha, está entre las más altas registradas para el Neotrópico, y corrobora el patrón de distribución de riqueza ligado a altas precipitaciones. La mayoría de las especies están representadas por pocos individuos, mientras que unas pocas son las más abundantes y frecuentes. Se identificó un grupo de especies (Wettinia quinaria, Welfia regia, Iriartea deltoidea, Socratea exorrhiza, Oenocarpus bataua, en el dosel, y Geonoma cuneata, en el sotobosque, que son particularmente importantes a nivel ecológico, y que caracterizan y modelan la vegetación, no sólo del área de estudio, sino también, al parecer, a lo largo de la región del Chocó Biogeográfico. Con base en los resultados y en otros datos florísticos, se plantea que, si bien las palmas son importantes a todo lo largo de la región, la mayor abundancia y riqueza parece presentarse hacia la zona central, que coincide con un aumento en el gradiente de precipitación. Veintisiete de las 33 especies encontradas tenía algún uso en una de las siete categorías de uso, lo cual muestra la importancia de las palmas para las poblaciones locales.

ESTRUCTURA Y DIVERSIDAD FLORISTICA DE DOS BOSQUES NATURALES (BUENOS AIRES, DPTO CAUCA, COLOMBIA ESTRUTURA E DIVERSIDADE FLORÍSTICA DE DUAS FLORESTAS NATURAIS NO MUNICIPIO DE BUENOS AIRES, DEPARTAMENTO DO CAUCA, COLOMBIA STRUCTURE AND FLORISTIC DIVERSITY FROM TWO FORESTS IN BUENOS AIRES, CAUCA, COLOMBIA

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CATALINA GARCÍA

2010-06-01

Full Text Available Se describe la estructura y diversidad florística de dos transectos en el bosque andino del Municipio de Buenos Aires, Departamento del Cauca. El muestreo se realizó en los Corregimientos El Ceral y El Porvenir, en cada uno de ellos se estableció un transecto de 0,5 ha (250m x20m. En ellos se determinaron y se registraron las especies presentes y se midió el diámetro a la altura del pecho (DAP de todos los individuos con DAP ≥ 10 cm. La estructura de los bosques estudiados presentan una distribución diamétrica en forma de "J invertida", la cual expresa la dinámica del bosque, también se elaboró un perfil esquemático de cada bosque. La diversidad de especies se estimó con los índices de Margalef Menihnick, Shannon -Winnery Simpson. La similitud florística entre los bosques se valoró con los índices de similitud de Jaccardy Sorensen. La curva especie - área o de riqueza florística no llegó al punto de inflexión, donde las especies nuevas dejaron de ser encontradas, debido a que en gran parte son especies raras.Descreve-se a estructura e diversidade florística de dois bosques andinos no Municipio de Buenos Aires, Departamento do Cauca. A demonstacão se fez nos povoados "El Ceral e El Porvenir". Em cada um deles se estableceu um trajeto de 0,5 hetares (250m x 20m. Neles se determinaram e registraram as espécies presentes e se mediu o diámetro À altura do peito (DAP de todos os individuos com DAP≥10 cm. A estructura das florestas estudadas apresenta urna distribuiçÃo dia-métrica em forma de "J invés", a qual expressa a dinámica do mato, também se elaborou um perfil esquemático de cada urna das florestas. A diversidade de especies estimou-se com os índices de Margalef, Menihninck, Shannon - Wiener, Simpson e Berger Parker. A semelhança florística entre as duas florestas se valorou com os índices de similitude de Jaccard e Sorensen. A curva especie -área ou de riqueza florística, não chegou ao ponto de inflex

Bosques y suelos en el contexto de redd+: entre gobierno y gobernanza en México

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Antoine Libert Amico

2016-01-01

Full Text Available El reciente énfasis en la reducción de emisiones por deforestación y degradación (REDD+ ha generado una reconfiguración de las formas de gestión ambiental en México. Mediante el uso de datos generados por los autores dentro de un proyecto de investigación sobre Gobernanza Multinivel y Gestión de Carbono a Nivel de Paisaje, del Centro para la Investigación Forestal Internacional (CIFOR, se muestran los retos que enfrentan nuevos arreglos de gobernanza en torno a bosques y suelos. Se marca la diferencia entre gobierno y gobernanza, buscando ilustrar la transición de uno al otro en el marco de los programas de acción temprana REDD+ y el potencial de innovación que el escenario actual de debates sobre cambio climático ha creado. Al final se invita a una reflexión sobre las posibles contribuciones de una gobernanza forestal democrática, legítima y transparente para la gestión de los suelos y de los desafíos ambientales.

Tidal Simulations of an Incised-Valley Fluvial System with a Physics-Based Geologic Model

Science.gov (United States)

Ghayour, K.; Sun, T.

2012-12-01

Physics-based geologic modeling approaches use fluid flow in conjunction with sediment transport and deposition models to devise evolutionary geologic models that focus on underlying physical processes and attempt to resolve them at pertinent spatial and temporal scales. Physics-based models are particularly useful when the evolution of a depositional system is driven by the interplay of autogenic processes and their response to allogenic controls. This interplay can potentially create complex reservoir architectures with high permeability sedimentary bodies bounded by a hierarchy of shales that can effectively impede flow in the subsurface. The complex stratigraphy of tide-influenced fluvial systems is an example of such co-existing and interacting environments of deposition. The focus of this talk is a novel formulation of boundary conditions for hydrodynamics-driven models of sedimentary systems. In tidal simulations, a time-accurate boundary treatment is essential for proper imposition of tidal forcing and fluvial inlet conditions where the flow may be reversed at times within a tidal cycle. As such, the boundary treatment at the inlet has to accommodate for a smooth transition from inflow to outflow and vice-versa without creating numerical artifacts. Our numerical experimentations showed that boundary condition treatments based on a local (frozen) one-dimensional approach along the boundary normal which does not account for the variation of flow quantities in the tangential direction often lead to unsatisfactory results corrupted by numerical artifacts. In this talk, we propose a new boundary treatment that retains all spatial and temporal terms in the model and as such is capable to account for nonlinearities and sharp variations of model variables near boundaries. The proposed approach borrows heavily from the idea set forth by J. Sesterhenn1 for compressible Navier-Stokes equations. The methodology is successfully applied to a tide-influenced incised

Cross-stratified Wood: Enigmatic Woody Debris Deposits in Warm-Polar Fluvial Sediments (Pliocene Beaufort Formation, Nunavut)

Science.gov (United States)

Davies, N. S.; Gosse, J. C.; Rybczynski, N.

2012-04-01

Woody debris has been an important sediment component and a significant geomorphic agent in pristine fluvial systems since the Devonian. In recent years a large volume of research has focussed on various aspects of the importance of woody debris within the fluvial realm; from the evolutionary significance of fossil wood accumulations in the rock record to studies of the biogeomorphological and ecological importance of woody debris in modern rivers. In this presentation we describe cross-stratified woody debris deposits comprising organic detritus from a boreal-type treeline forest that included species of pine, birch, poplar, alder, spruce, eastern cedar, and larch, in both shrub and tree form. The cross-stratified wood is an enigmatic subset of fine woody debris which, to our knowledge, has never before been described from either the global stratigraphic record or modern fluvial environments. The deposits we describe are located within the Pliocene Beaufort Formation on Meighen Island, Nunavut, Canada, at a latitude of 80°N, and are compared with other cross-stratified woody debris deposits that have been noted elsewhere in the Pliocene of the Canadian Arctic. We make the robust observation that these deposits appear to be geographically and stratigraphically restricted to polar latitudes from a period of warm climatic conditions during the Pliocene (15-20 °C warmer mean annual temperature than the present day). In this regard it is possible to speculate that the transport of large amounts of woody debris as bedload is potentially a unique feature of forested high latitude rivers. Such bedload deposition requires a large amount of woody debris with a greater density than the fluid transporting it. The softwood composition of the debris suggests that this was most likely attained by saturation and subsequent entrainment of extensive accumulations of deadwood, promoted by unusually high rates of tree mortality and low rates of bacterial decomposition arising from

Formation of topographically inverted fluvial deposits on Earth and Mars

Science.gov (United States)

Hayden, A.; Lamb, M. P.; Fischer, W. W.; Ewing, R. C.; McElroy, B. J.

2016-12-01

Sinuous ridges interpreted as exhumed river deposits (so-called "inverted channels") are common features on Mars that show promise for quantifying ancient martian surface hydrology. Morphological similarity of these inverted channels to river channels led to a "landscape inversion hypothesis" in which the geometries of ridges and ridge networks accurately reflect the geometries of the paleo-river channels and networks. An alternative "deposit inversion hypothesis" proposes that ridges represent eroded fluvial channel-belt deposits with channel-body geometries that may differ significantly from those of the rivers that built the deposit. To investigate these hypotheses we studied the sedimentology and morphology of inverted channels in Jurassic and Cretaceous outcrops in Utah and the Aeolis Dorsa region of Mars. Ridges in Utah extend for hundreds of meters, are tens of meters wide, and stand up to 30 meters above the surrounding plain. A thick ribbon-geometry sandstone or conglomerate body caps overbank mudstone, paleosols, and thin crevasse-splay sandstone beds. Caprock beds consist of stacked dune- to bar-scale trough cross sets, mud intraclasts, and in cases scroll bars indicating meandering. In plan view, ridge networks bifurcate; however, crosscutting relationships show that distinct sandstone channel bodies at distinct stratigraphic levels intersect at these junctions. Ridge-forming sandstone bodies have been narrowed from their original dimensions by cliff retreat and bisected by modern fluvial erosion and mass wasting. We therefore interpret the sinuous ridges in Utah as eroded remnants of channel-belt sandstone bodies formed by laterally migrating and avulsing rivers rather than channel fills - consistent with deposit inversion. If the sinuous ridges in Aeolis Dorsa also formed by deposit inversion, river widths previously interpreted under the landscape inversion hypothesis are overestimated by up to a factor of 10 and discharges by up to a factor of 100.

Fluvial sediment transport in a glacier-fed high-mountain river (Riffler Bach, Austrian Alps)

Science.gov (United States)

Morche, David; Weber, Martin; Faust, Matthias; Schuchardt, Anne; Baewert, Henning

2017-04-01

High-alpine environments are strongly affected by glacier retreat since the Little Ice Age (LIA). Due to ongoing climate change the hydrology of proglacial rivers is also influenced. It is expected that the growing proportions of snow melt and rainfall events will change runoff characteristics of proglacial rivers. Additionally, the importance of paraglacial sediment sources in recently deglaciating glacier forefields is increasing, while the role of glacial erosion is declining. Thus complex environmental conditions leading to a complex pattern of fluvial sediment transport in partly glaciated catchments of the European Alps. Under the umbrella of the joint PROSA-project the fluvial sediment transport of the river Riffler Bach (Kaunertal, Tyrol, Austria) was studied in 3 consecutive ablation seasons in order to quantify sediment yields. In June 2012 a probe for water level and an automatic water sampler (AWS) were installed at the outlet of the catchment (20km2). In order to calculate annual stage-discharge-relations by the rating-curve approach, discharge (Q) was repeatedly measured with current meters and by salt dilution. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In total 564 (2012: 154, 2013: 209, 2014: 201) water samples were collected and subsequently filtered to quantify suspended sediment concentrations (SSC). Q-SSC-relations were calculated for single flood events due to the high variability of suspended sediment transport. The results show a high inter- and intra-annual variability of solid fluvial sediment transport, which can be explained by the characteristics of suspended sediment transport. Only 13 of 22 event-based Q-SSC-relations show causal dependency. In 2012, during a period with multiple pluvial-induced peak discharges most sediment was transported. On the

Perfil cualitativo de metabolitos secundarios en la fracción comestible de especies leñosas seleccionadas por vacunos en un bosque semicaducifolio

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Á Ojeda

Full Text Available Con el fin de caracterizar cualitativamente el perfil de metabolitos secundarios de la fracción comestible de plantas leñosas seleccionadas por vacunos en silvopastoreo, las cuales se encuentran en un bosque tropófilo semicaducifolio de Venezuela, se utilizaron 14 vacunos machos Brahman x Holstein de 390,4 ± 18,0 kg de PV. Estos fueron manejados en pastoreo continuo en una superficie de 81 ha, de las cuales 50 ha correspondían a un bosque semicaducifolio y el resto, a vegetación herbácea natural (Cynodon nlemfuensis, Sporobolus indicus, Axonopus sp., Mimosa pudica e Hyptis suaveolens. La composición de la biomasa leñosa seleccionada por los animales se estudió mediante la evaluación de los fragmentos epidérmicos presentes en las heces colectadas por vía transrectal, cada 15 días. A partir de estos resultados, se tomaron muestras de cinco plantas por especie leñosa, en los periodos seco y lluvioso. Se determinaron 15 grupos de metabolitos: alcaloides, á-aminos, carbohidratos solubles, cardenólidos, cianógenos, esteroles, fenoles totales, flavonoides, lectinas, mucílagos, quinonas, saponinas, taninos extractables (totales y condensados y terpenoides. La mayoría de la biomasa correspondió a especies de la familia Fabaceae, las cuales presentaron todos los metabolitos evaluados. En ambos periodos se detectaron niveles de esteroles, terpenoides, fenoles totales y taninos extractables que variaron desde leves hasta cuantiosos. Con independencia del periodo, el 66,7 % de las especies presentó entre 10-11 metabolitos secundarios en su biomasa comestible. Se recomienda realizar estudios para la cuantificación de los metabolitos secundarios presentes en plantas leñosas de valor forrajero, para este sistema silvopastoril

Characterization of organic matter in dusts and fluvial sediments from exposed areas of dowtown Prague, Czech Republic

Czech Academy of Sciences Publication Activity Database

Sýkorová, Ivana; Havelcová, Martina; Trejtnarová, Hana; Matysová, Petra; Vašíček, Michal; Suchý, V.; Kříbek, B.

2009-01-01

Roč. 80, č. 2 (2009), s. 69-86 ISSN 0166-5162 R&D Projects: GA AV ČR IAA300460804 Institutional research plan: CEZ:AV0Z30460519 Keywords : dust * fluvial sediment * carbonaceous particles Subject RIV: DD - Geochemistry Impact factor: 1.924, year: 2009

Middel Pleistocene to Holocene fluvial terrace development and uplift-driven valley incision in the SE Carpathians, Romania

NARCIS (Netherlands)

Necea, D.; Fielitz, W.; Andriessen, P.A.M.; Dinu, C.

2013-01-01

This study reveals that in the SE Carpathians terrace development and fluvial incision during the Middle Pleistocene-Holocene are predominantly controlled by tectonic uplift as shown by terrace distributions and uplift amounts and rates. The work focuses on a transect from the internal nappes and

Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios

International Nuclear Information System (INIS)

Mouri, Goro

2015-01-01

For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity

Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios

Energy Technology Data Exchange (ETDEWEB)

Mouri, Goro, E-mail: mouri@rainbow.iis.u-tokyo.ac.jp

2015-11-15

For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity

Conservación del bosque y fauna del Colegio Liceo Nacional como estrategia de educación ambiental en Ibagué, Tolima, Colombia

Directory of Open Access Journals (Sweden)

Marcela Cubillos

2005-07-01

más de 70 especies vegetales (excluyendo arbustos y herbáceas, y 25 especies animales entre aves, mamíferos y reptiles, destacándose la presencia del tití gris (Saguinus leucopus. Además, se llevaron a cabo cuatro talleres teóricoprácticos donde las alumnas conocieron las especies vegetales y animales que existen en el colegio, así como algunas nociones de taxonomía de aves, anfibios y reptiles presentes en el departamento del Tolima, Colombia. Con estas actividades se logró incentivar el sentido de pertenencia, conciencia ecológica y conservacionista en las alumnas y docentes por el bosque y fauna del colegio Liceo Nacional.

Geocronología de los yacimientos achelenses de Pinedo y Cien Fanegas (Valle del Tajo) e implicaciones en la evolución fluvial en el entorno de Toledo (España)

DEFF Research Database (Denmark)

López-Recio, M.; Silva, P. G.; Roquero, E.

2015-01-01

This study presents the first geochronological data from several research projects focused on the chronostratigraphy of the Tagus fluvial terraces in the environs of Toledo city (Central Spain). The research is centered on Middle to Late Pleistocene fluvial terraces with palaeontological and Ache...

Compound simulation of fluvial floods and storm surges in a global coupled river-coast flood model: Model development and its application to 2007 Cyclone Sidr in Bangladesh

Science.gov (United States)

Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip J.; Winsemius, Hessel C.; Verlaan, Martin; Kanae, Shinjiro

2017-08-01

Water-related disasters, such as fluvial floods and cyclonic storm surges, are a major concern in the world's mega-delta regions. Furthermore, the simultaneous occurrence of extreme discharges from rivers and storm surges could exacerbate flood risk, compared to when they occur separately. Hence, it is of great importance to assess the compound risks of fluvial and coastal floods at a large scale, including mega-deltas. However, most studies on compound fluvial and coastal flooding have been limited to relatively small scales, and global-scale or large-scale studies have not yet addressed both of them. The objectives of this study are twofold: to develop a global coupled river-coast flood model; and to conduct a simulation of compound fluvial flooding and storm surges in Asian mega-delta regions. A state-of-the-art global river routing model was modified to represent the influence of dynamic sea surface levels on river discharges and water levels. We conducted the experiments by coupling a river model with a global tide and surge reanalysis data set. Results show that water levels in deltas and estuaries are greatly affected by the interaction between river discharge, ocean tides and storm surges. The effects of storm surges on fluvial flooding are further examined from a regional perspective, focusing on the case of Cyclone Sidr in the Ganges-Brahmaputra-Meghna Delta in 2007. Modeled results demonstrate that a >3 m storm surge propagated more than 200 km inland along rivers. We show that the performance of global river routing models can be improved by including sea level dynamics.

Reconstructing Early Pleistocene (1.3 Ma) terrestrial environmental change in western Anatolia: Did it drive fluvial terrace formation?

NARCIS (Netherlands)

Veldkamp, A.; Candy, I.; Jongmans, A.G.; Maddy, D.; Demir, T.; Schoorl, J.M.; Schreve, D.; Stemerdink, C.; Schriek, van der T.

2015-01-01

A terrestrial environmental reconstruction of an Early Pleistocene landscape from western Anatolia is presented. The basis of this reconstruction is a sedimentary stack comprising fluvial and colluvial slope deposits. Contained within this stack is a sequence comprising two massive laminar calcretes

Sediment Transport Dynamic in a Meandering Fluvial System: Case Study of Chini River

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Nazir, M. H. M.; Awang, S.; Shaaban, A. J.; Yahaya, N. K. E. M.; Jusoh, A. M.; Arumugam, M. A. R. M. A.; Ghani, A. A.

2016-07-01

Sedimentation in river reduces the flood carrying capacity which lead to the increasing of inundation area in the river basin. Basic sediment transport can predict the fluvial processes in natural rivers and stream through modeling approaches. However, the sediment transport dynamic in a small meandering and low-lying fluvial system is considered scarce in Malaysia. The aim of this study was to analyze the current riverbed erosion and sedimentation scenarios along the Chini River, Pekan, Pahang. The present study revealed that silt and clay has potentially been eroded several parts of the river. Sinuosity index (1.98) indicates that Chini River is very unstable and continuous erosion process in waterways has increase the riverbank instability due to the meandering factors. The riverbed erosional and depositional process in the Chini River is a sluggish process since the lake reduces the flow velocity and causes the deposited particles into the silt and clay soil at the bed of the lake. Besides, the bed layer of the lake comprised of cohesive silt and clayey composition that tend to attach the larger grain size of sediment. The present study estimated the total sediment accumulated along the Chini River is 1.72 ton. The HEC-RAS was employed in the simulations and in general the model performed well, once all parameters were set within their effective ranges.

La Pérdida de Espacios Fluviales en Andalucía (1956-2007. Una Aproximación Escalar.

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David González-Rojas

2017-12-01

Full Text Available Desde mediados del siglo pasado, los espacios fluviales andaluces han conocido un acelerado proceso de degradación. En el presente artículo se realiza una aproximación histórica y multiescalar de la distribución de estos espacios a partir de los mapas de usos y coberturas vegetales. A escala regional, se evidencia que Andalucía ha perdido una décima parte de los espacios fluviales en seis décadas. En segundo lugar, se analiza, a escala local, dos casos paradigmáticos (río Guadalmina y río Guadalquivir y extensibles al resto del territorio. El esfuerzo realizado para la ordenación de los ríos no ha tenido su reflejo en los resultados obtenidos, siendo las interrelaciones entre la gestión del agua y del territorio (regional, subregional y municipal una cuestión no resuelta.

The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

Science.gov (United States)

Rengers, Francis K.; McGuire, Luke; Ebel, Brian A.; Tucker, G. E.

2018-01-01

The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles ( >D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.

The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

Science.gov (United States)

Rengers, F. K.; McGuire, L. A.; Ebel, B. A.; Tucker, G. E.

2018-05-01

The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles (>D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.

Distribución y abundancia de murciélagos en bosques con diferente grado de intervención en el Parque Nacional Natural Gorgona (Colombia

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Oscar Enrique Murillo-García

2014-02-01

Full Text Available Se cuantificó la variación de la comunidad de murciélagos en bosques con diferente grado de intervención en el Parque Nacional Natural Gorgona. Para esto se realizaron capturas en tres zonas (dos sitios en cada zona durante tres eventos de muestreo. El análisis de datos consideró la detección imperfecta, permitiendo realizar una inferencia confiable acerca de los cambios en presencia, abundancia y riqueza entre tipos de coberturas. Los resultados evidenciaron una considerable variación en detectabilidad relacionada con variaciones entre gremios tróficos y tipos de cobertura. Las tasas de presencia aumentaron al disminuir la cobertura boscosa (Ψb.intervenido>Ψb. secundario>Ψb. primario y fueron diferentes entre especies. La abundancia incrementó al aumentar el nivel de intervención (Nb.intervenido>Nb.secundario>Nb primario, disminuyó con el tamaño corporal y fue mayor para frugívoros y nectarívoros que para insectívoros. Los resultados sugieren que las comunidades de murciélagos despliegan fuertes respuestas al grado de intervención. Aunque se presentó mayor presencia y abundancia en el área más intervenida, los murciélagos también utilizaron las menos intervenidas. Esto puede incrementar el movimiento de las semillas entre diferentes estadíos sucesionales. Por lo tanto, el estudio de la comunidad de murciélagos puede ser importante para monitorear el estado de recuperación de los bosques del PNN Gorgona y para entender los procesos ecológicos que generan la recuperación de estos.

Evidence of population resistance to extreme low flows in a fluvial-dependent fish species

Science.gov (United States)

Katz, Rachel A.; Freeman, Mary C.

2015-01-01

Extreme low streamflows are natural disturbances to aquatic populations. Species in naturally intermittent streams display adaptations that enhance persistence during extreme events; however, the fate of populations in perennial streams during unprecedented low-flow periods is not well-understood. Biota requiring swift-flowing habitats may be especially vulnerable to flow reductions. We estimated the abundance and local survival of a native fluvial-dependent fish species (Etheostoma inscriptum) across 5 years encompassing historic low flows in a sixth-order southeastern USA perennial river. Based on capturemark-recapture data, the study shoal may have acted as a refuge during severe drought, with increased young-of-the-year (YOY) recruitment and occasionally high adult immigration. Contrary to expectations, summer and autumn survival rates (30 days) were not strongly depressed during low-flow periods, despite 25%-80% reductions in monthly discharge. Instead, YOY survival increased with lower minimum discharge and in response to small rain events that increased low-flow variability. Age-1+ fish showed the opposite pattern, with survival decreasing in response to increasing low-flow variability. Results from this population dynamics study of a small fish in a perennial river suggest that fluvial-dependent species can be resistant to extreme flow reductions through enhanced YOY recruitment and high survival

Caracterización estacional del hábitat fluvial del río Erro (Navarra

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P.M. Leunda, R. Miranda, M.C. Escala

2004-01-01

Full Text Available Se presenta la descripción de catorce tramos representativos del río Erro (Navarra a partir de la caracterización del hábitat fluvial llevada a cabo en invierno, verano y otoño de 2002. Para este estudio se han considerado parámetros tanto del hábitat físico (profundidad, anchura del cauce, pendiente de las orillas, velocidad del agua, tipo de sustrato, vegetación acuática y sombreado como físico-químicos del agua (temperatura, pH, conductividad, sólicos disueltos y oxigeno disuelto. El análisis de las caracteristicas del rio Erro permite considerar su estado general como bueno, aunque se detecta la presencia de un tramo sensible aguas abajo de la localidad de Erro. Si bien este tramo sensible presenta niveles de conservación aceptables, es susceptible de deteriorarse si no de adoptan las medidas oportunas para su conservación. Se sugiere su inclusión en el Lugar de Interés Comunitario (Red Natura 2000 de Navarra de los "Sistemas Fluviales de lis Ríos Irati, Urrobi y Erro".

Milankovitch cyclicity in the paleotropical, fluvial, Late Triassic age strata recovered by the Colorado Plateau Coring Project (CPCP)

Science.gov (United States)

Olsen, P. E.; Mundil, R.; Kent, D.; Rasmussen, C.

2017-12-01

Two questions addressed by the CPCP are: 1) is Milankovitch-paced climate cyclicity recorded in the fluvial Late Triassic age Chinle Formation ( 227-202 Ma); and 2) do geochronological data from the Chinle support the Newark-Hartford astrochronological polarity time scale (1) (APTS). To these ends we examined the upper 157 m (stratigraphic thickness) of Petrified Forest National Park core 1A (Owl Rock, Petrified Forest, and upper Sonsela members), consisting mostly of massive red paleosols and less important fluvial sandstones. A linear age model tied to new U-Pb zircon CA ID-TIMS dates from core 1A, consistent with published data from outcrop (2), yields a duration of about 5 Myr for this interval. Magnetic susceptibility variations, interpreted as reflecting penecontemporaneous soil and sandstone redox conditions, show a clear 12 m cycle corresponding to a 400 kyr cycle based on Fourier analysis in both core and hole. Similar cyclicity is apparent in spectrophotometric data, largely reflecting hematite variability. Weak, higher frequency cycles are present consistent with 100 kyr variability. There is no interpretable 20 kyr signal. Such cyclicity is not an anticipated direct effect of Milankvitch insolation variations, but must reflect non-linear integration of variability that changes dramatically at the eccentricity-scale, brought about by the sedimentary and climate systems. Our results support a direct 405 kyr-level correlation between the fluvial medial Chinle and lacustrine Newark Basin section (middle Passaic Formation), consistent with new and published (3) paleomagnetic polarity stratigraphy from the Chinle, showing that the Milankovitch eccentricity cycles are recorded in lower accumulation rate fluvial systems. Our results also independently support the continuity of the Newark Basin section and corroborate the Newark-Hartford APTS, not allowing for a multi-million year hiatus in the Passaic Formation, as has been asserted (4). We anticipate further

Fluvial sedimentology of a major uranium-bearing sandstone - A study of the Westwater Canyon member of the Morrison Formation, San Juan Basin, New Mexico

International Nuclear Information System (INIS)

Turner-Peterson, C.E.

1986-01-01

The Westwater Canyon Member of the Morrison Formation, the main ore-bearing sandstone in the San Juan basin, consists of a sequence of vertically stacked braided stream deposits. Three fluvial units within the sequence can be delineated in the basin. Volcanic pebbles are abundant in the middle fluvial unit, in a zone that forms a crude time line. A pronounced thickening of sandstone in the Westwater Canyon Member north of Gallup, once believed to be the apex of a large alluvial fan, is now thought to merely reflect a greater accumulation of sediment in response to downwarping of the basin in that area. Provenance studies suggest that highlands that contributed detritus to Westwater Canyon streams were located several hundred kilometers to the west and southwest of the San Juan basin, and thus fan apices would also have been several hundred kilometers upstream. The fluvial units recognized in the basin may well be coalesced distal fan deposits, but are probably best interpreted as vertically stacked braided steam sequences. Facies changes in fine-grained interbeds of the Westwater Canyon probably have greater significance in terms of localizing ore than any special attribute of the fluvial sandstones themselves. Uranium ore generally occurs in sandstones that are interbedded with greenish-gray lacustrine mudstones. Pore waters that were expelled from these mudstones are thought to have been the source of the pore-filling organic matter (humate) associated with primary uranium ore in nearby sandstones

Reconstructing late quaternary fluvial process controls in the upper aller valley (north Germany) by means of numerical modeling

NARCIS (Netherlands)

Veldkamp, A.; Berg, van den M.; Dijke, van J.J.; Berg van Saparoea, van den R.M.

2002-01-01

The morpho-genetic evolution of the upper Aller valley (Weser basin, North Germany) was reconstructed using geological and geomorphologic data integrated within a numerical process model framework (FLUVER-2). The current relief was shaped by Pre-Elsterian fluvial processes, Elsterian and Saalian ice

Reconstructing Late Quaternary fluvial process controls in the upper Aller Valley (North Germany) by means of numerical modeling

NARCIS (Netherlands)

Veldkamp, A.; Berg, M.W. van den; Dijke, J.J. van; Berg van den; Saparoea, R.M. van

2002-01-01

The morpho-genetic evolution of the upper Aller valley (Weser basin, North Germany) was reconstructed using geological and geomorphologic data integrated within a numerical process model framework (FLUVER-2). The current relief was shaped by Pre-Elsterian fluvial processes, Elsterian and Saalian ice

Una breve descripción de la vegetación, con especial énfasis en las pioneras intermedias de los bosques secos de la Jagua, en la cuenca alta del Rio Magdalena en el Huila

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William Gerardo Vargas

2015-01-01

Full Text Available Se revisó la información existente sobre la flora de los bosques secos del sur del departamento del Huila, con especial interés en la de La Jagua y sus alrededores con el fin de identificar especies pioneras intermedias que puedan apoyar procesos de restauración ecológica y conservación de la biodiversidad. Para los bosques secos del departamento se identificaron 203 especies pioneras intermedias distribuidas en 123 géneros y 45 familias botánicas, mientras que para La Jagua 153 especies agrupadas en 109 géneros y 42 familias, entre las que sobresalen Fabaceae,  Rubiaceae, Malvaceae, Moraceae y Anacardiaceae. Se proponen 85 especies consideradas claves para procesos de conservación, la restauración de los ecosistemas secos de la región dirigida a la generación de hábitat y de conectividad, la producción de recursos para la fauna, así como la producción de leña y madera para las comunidades dentro de un modelo de herramientas de manejo del paisaje.

Étude préliminaire de recrutement fluvial de l'anguille

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LEGAULT A.

1994-10-01

La passe piège représente la seule voie de franchissement de l'obstacle. L'évaluation des captures permet d'estimer le taux de recrutement du bassin versant pour l'année 1992. Il s'établit à 561 individus par km2 de bassin versant. L'évaluation annuelle de ce taux pourrait être utilisée afin de suivre la dynamique du stock à l'échelle du bassin versant. Ces évaluations, conduites à l'échelle de l'aire de répartition européenne de l'anguille, pourraient permettre d'établir le recrutement fluvial annuel et ses fluctuations.

Phytolith analysis in fluvial quaternary sediment (San Salvador and Palmar formation) Uruguay river and Argentina eastern

International Nuclear Information System (INIS)

Patterer, N.; Passeggi, E.; Zucol, A.; Brea, M.; Krohling, D.

2012-01-01

This work is about two microfossils fluvial units deposited by the Uruguay river during the Quaternary. These are San Salvador and Palmar formation (Plio-Pleistocene - Upper Pleistocene).The Palmar formation is a band of 4-15 km along the right bank of the Uruguay river outcropping from the eastern provinces of Corrientes and Entre Rios, to Concepcion del Uruguay

Inusual riqueza, composición y estructura arbórea en el bosque de tierra firme del Pongo Qoñec, Sur Oriente peruano

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Isau Huamantupa-Chuquimaco

2011-05-01

Full Text Available Se estableció una parcela de 1 ha, en bosque de tierra firme en el Pongo de Qoñec, valle Kosñipata (Cusco, dentro de la Reserva Biósfera del Manú, a 710 m; 12°53'53"S y 72°22'25"W. Se registró 56 familias, 153 géneros, 249 especies con 813 individuos con Dap ≥ 10 cm. Las familias, más ricas fueron: Fabaceae (32 especies, Moraceae (24, Rubiaceae (17 y Lauraceae (12; los géneros más ricos, Inga (17, Neea (7, Miconia (5; se halló un área basal total de 40,50 m2, de ellas Iriartea deltoidea con 6,58 m2, Socratea salazarii 2,28 m2, y Endlicheria sp 1,65 m2, obtuvieron mayor ab; la especie con mayor valor de importancia fue: I. deltoidea, cor- roborando estudios anteriores en bosques de tierra firme. El análisis estructural muestra que clases diamétricas 10-20 cm, abarcan 71,3% del total de fustes. Al comparar nuestros resultados, el Pongo de Qoñec, sorpren- dentemente supera en riqueza a parcelas adyacentes dentro del sur peruano y muestra un patrón de riqueza de familias y géneros similar a parcelas peruanas diversas como Yanamono 300 especies y Mishana (289, en Loreto. Consideramos que esta inusual riqueza se debe en gran medida a factores ambientales únicos que se dan en este Pongo, como son la alta precipitación, dinámica de vientos y la variabilidad de suelos en áreas pequeñas. Por tanto estos resultados difieren considerablemente de enunciados conocidos, que consideran a la amazonia sur peruana con moderada a baja riqueza arbórea.

Relevance of the Paraná River hydrology on the fluvial water quality of the Delta Biosphere Reserve.

Science.gov (United States)

Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

2016-06-01

The increasing frequency of extreme events in large rivers may affect not only their flow, but also their water quality. In the present study, spatial and temporal changes in fluvial physico-chemical variables were analyzed in a mega-river delta during two extreme hydrological years (La Niña-El Niño) and related to potential explanatory factors. Basic water variables were evaluated in situ at 13 points (distant 2-35 km from each other) in watercourses of the Delta Biosphere Reserve (890 km(2)) in the Lower Paraná River (Argentina) in nine surveys (October 2008-July 2010) without meteorological tides. Samples for laboratory analyses were collected from each main river. Multivariate tests by permutations were applied. The period studied was influenced by a drought, within a long period dominated by low flows combined with dry weather and wildfires, and a large (10 years of recurrence) and prolonged (7 months) flood. The hydrological phase, followed by the season and the hydrological year (according to the ENSO event) were the principal explanatory factors of the main water quality changes, whereas the drainage sub-basin and the fluvial environment (river or stream) were secondary explanatory factors. During the drought period, conductivity, turbidity, and associated variables (e.g., major ions, silicon, and iron concentrations) were maximal, whereas real color was minimal. In the overbanking flood phase, pH and dissolved oxygen concentration were minimal, whereas real color was maximal. Dissolved oxygen saturation was also low in the receding flood phase and total major ion load doubled after the arrival of the overbanking stage. The water quality of these watercourses may be affected by the combination of several influences, such as the Paraná River flow, the pulses with sediments and solutes from the Bermejo River, the export of the Delta floodplain properties mainly by the flood, the season, and the saline tributaries to the Lower Paraná River. The high

Implications of sedimentological studies for environmental pollution assessment and management: Examples from fluvial systems in North Queensland and Western Australia

Science.gov (United States)

Eyre, Bradley; McConchie, David

1993-05-01

Sedimentology is of increasing importance in environmental research, particularly environmental pollution studies, where past trends in environmental processes need to be combined with data on present conditions to predict likely future changes—the past and present as a key to the future. Two examples are used to illustrate the role of sedimentology in assessing the influence of major processes on the transport, accumulation, deposition and modification of contaminants in fluvial/estuarine systems and in developing environmental management plans. Example 1 shows that when assessing nutrient behaviour in fluvial/estuarine depositional settings, it is important to examine the partitioning of phosphorus between grain size fractions to evaluate the sedimentological processes which control the dispersion and trapping of these contaminants. Example 2 shows that in studies of anthropogenic metal inputs to modern depositional settings, lateral and stratigraphic trends in sediment texture and mineralogy should be examined, in addition to trends in metal loads and evaluation of the prevailing physical, chemical and biological processes that may influence metal mobility and dispersion. Clearly, basic sedimentological data should form part of any assessment of potentially contaminated sites and part of investigations into the dispersion and trapping of contaminants in fluvial systems. These data are also required for rational environmental management to ensure that planning decisions are compatible with natural environmental constraints.

DOS SISTEMAS AMBIENTAIS AO SISTEMA FLUVIAL – UMA REVISÃO DE CONCEITOS

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Jonas Otaviano Praça de Souza

2013-10-01

Full Text Available Tentando consolidar as noções de totalidade, a geografia física passa a utilizar a noção de sistemas dinâmicos, não lineares e de comportamento caótico. Deste modo, a abordagem sistêmica/complexa apresenta-se como meio de compreensão do mundo natural, assim possibilitando a previsão de mudanças, avaliação dos sistemas ambientais, distúrbios e limiares do sistema. Nota-se, assim, a importância dos estudos processuais para o gerenciamento de recursos hídricos, tornando imprescindíveis estudos sistêmicos que analisem os diversos elementos importantes para a análise dos recursos hídricos, dentre eles as questões processuais. Deste modo, a necessidade de se trabalhar o gerenciamento integrado de recursos hídricos, enquadrado na perspectiva sistêmica, solidificou a bacia hidrográfica e/ou bacia de drenagem como recorte espacial sistêmico. Delimitada a área pode-se compreender a bacia hidrográfica como um Sistema Fluvial, conceituado por Schumm (1977, que é analisado a partir da zona fonte de sedimentos, da rede de transporte e dos sítios de deposição. Esses elementos não são espacialmente excludentes, interagindo entre si, além de apresentar escalas diferenciadas. Para o estudo do sistema fluvial é necessário levar em consideração quatro conceitos: uniformidade dos processos, limiares de mudança, evolução da paisagem e respostas complexas.

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron

Science.gov (United States)

Signorella, J. D.; de Wet, A. P.; Bleacher, J. E.; Collins, A.; Schierl, Z. P.; Schwans, B.

2012-03-01

This study focuses on the source area of sinuous channels on the southeast rift apron on Ascraeus Mons, Mars and attempts to understand whether the channels were formed through volcanic or fluvial processes.

Alteraciones de los bosques nativos en el norte argentino: normativas y mecanismos de compensación por servicios ambientales

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Claudia Luna

2017-12-01

Full Text Available Los recursos naturales conforman los insumos de cualquier actividad económica desarrollada por el hombre; pero es una realidad que la mayoría de los ecosistemas forestales nativos de Argentina presentan desde serias alteraciones con su consecuente pérdida de biodiversidad; no hay mejor estrategia de política ambiental que aquélla que concurra simultáneamente a resolver los problemas ambientales y los socio-económicos con la insustituible acción del Estado. El objetivo de este trabajo es analizar la situación de los bosques del norte argentino luego de la ley de presupuestos mínimos para la protección ambiental de los mismos; para conocer en profundidad los procesos asociados a su alteración, las normativas vigentes para su protección y uso sustentable, como así también los mecanismos de compensación por servicios ambientales que surgen a partir de ellos.

A hydro-geochemical study of Nahr-Ibrahim catchment area: Fluvial metal transport

International Nuclear Information System (INIS)

Korfali, Samira

2004-01-01

Author.Metals enter water bodies geological weathering, soil erosion, industrial and domestic waste discharges, as well as atmospheric deposition. The metal content in sediments is a reflection of the nature of their background whether of geologic and/or anthropogenic origin. The depositional process of metals in sediment are controlled by river discharge, turbulence of river, morphology and river geometry, as well as the geochemical phases of sediment and soils. Thus a study of metal content in river and /or metal transport with a water body should include a hydrological study of the river, types of minerals in sediment and soil, sediment and soil textures, and metal speciation in the different geochemical phases of sediment, bank and soils. A contaminated flood plain is a temporary storage system for pollutants and an understanding of soil-sediment-interactions is important prerequisite for modeling fluvial pollutant transport. The determination of metal speciation in sediment and soil chemical fraction can provide information on the way in which these metals are bound to sediment and soil, their mobilization potential, bioavailability and possible mechanism of fluvial pollutant transport. Sequential extraction techniques yielding operationally defined chemical pools have been used by many workers to examine the partitioning of metals among the various geochemical phases of sediment or soil. The sequential extraction method specifies metals in sediment fractions as: exchangeable, specifically sorbed, easily reducible, moderately reducible, organic, residual. Previously, I have conducted a study on speciation of metals (Fe, Mn, Zn, Cu, Pb and Cd) in the dry season bed-load sediments only at five sites 13 km stretch upstream from the mouth of Nahr Ibrahim. The reported data revealed that the specifically sorbed sediment fraction was the prime fraction for deposition of Mn, Z, CU, Pb and Cd metals in sediments. X-ray diffraction analysis of bed sediments showed

RIQUEZA FLORÍSTICA, ENDEMISMO Y FORMAS DE VIDA DE LOS BOSQUES Y LOS MATORRALES DE LAS TERRAZAS COSTERAS DE LA RESERVA DE LA BIOSFERA BACONAO, CUBA

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LUZ MARGARITA FIGUEREDO CARDONA

2015-06-01

Full Text Available Se analizó la riqueza florística, el endemismo y las formas de vida de ocho tipos de vegetación entre bosques y matorrales de las terrazas costeras de la reserva de la biosfera Baconao. A partir de las recolectas en las expediciones de campo, la revisión de materiales de herbario e inventarios florísticos precedentes, se elaboró la lista de especies vegetales. Se identificaron 757 especies de 387 géneros y 87 familias botánicas. Del total, 108 son introducidas y 649 nativas, de éstas 164 son endémicas. Los matorrales costeros y los bosques semideciduos presentaron la mayor riqueza de especies y endemismos, además de alta similitud biológica, debido a las condiciones edáficas en que se desarrollan. Las familias con mayor riqueza específica fueron: Leguminosae (96, Malvaceae (58, Rubiaceae (42, Euphorbiaceae (41, Apocynaceae (34, Boraginaceae (33 y Poaceae (29. Predominaron los elementos de origen gondwánico (59.2 %, seguidos de los laurásicos (22.4 % y los de origen desconocido (18.4 %, con prevalecía de arbustos centro amazónicos. Se reconocieron 164 especies endémicas, de éstas 58 pancubanos, 45 sectoriales, 26 distritales y 35 multisectoriales. Es significativa la presencia de ocho géneros endémicos, siete monoespecíficos. Se registraron 35 especies amenazadas, 22 de ellas endémicas que se encuentran en áreas protegidas con categoría estricta de manejo. Se encontraron nueve formas de vida, con predominio de arbustos (283, árboles (179, hierbas (139 y trepadoras (108.

Temporal correlation of fluvial and alluvial sequences in the Makran Range, SE-Iran

Science.gov (United States)

Kober, F.; Zeilinger, G.; Ivy-Ochs, S.; Dolati, A.; Smit, J.; Burg, J.-P.; Bahroudi, A.; Kubik, P. W.; Baur, H.; Wieler, R.; Haghipour, N.

2009-04-01

The Makran region of southeastern Iran is an active accretionary wedge with a partially subaerial component. New investigations have revealed a rather complex geodynamic evolution of the Makran active accretionary wedge that is not yet fully understood in its entity. Ongoing convergence between the Arabian and Eurasian plates and tectonic activity since the late Mesozoic has extended all trough the Quaternary. We focus here on fluvial and alluvial sequences in tectonically separated basins that have been deposited probably in the Pliocene/Quaternary, based on stratigraphic classification in official geological maps, in order to understand the climatic and tectonic forces occurring during the ongoing accretionary wegde formation. Specifically, we investigate the influence of Quaternary climate variations (Pleistocene cold period, monsoonal variations) on erosional and depositional processes in the (semi)arid Makran as well as local and regional tectonic forces in the Coastal and Central Makran Range region. Necessary for such an analysis is a temporal calibration of alluvial and fluvial terrace sequences that will allow an inter-basin correlation. We utilize the exposure age dating method using terrestrial cosmogenic nuclides (TCN) due to the lack of otherwise datatable material in the arid Makran region. Limited radiocarbon data are only available for marine terraces (wave-cut platforms). Our preliminary 21Ne and 10Be TCN-ages of amalgamated clast samples from (un)deformed terrace and alluvial sequences range from ~250 ky to present day (modern wash). These ages agree in relative terms with sequences previously assigned by other investigations through correlation of Quaternary sequences from Central and Western Iran regions. However, our minimum ages suggest that all age sequences are of middle to late Pleistocene age, compared to Pliocene age estimates previously assigned for the oldest units. Although often suggested, a genetical relation and connection of those

Nuevos registros de aves en el bosque mesófilo de montaña del noreste de Hidalgo, México

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Miguel Angel Martínez-Morales

2015-06-01

Full Text Available Se reportan nuevos registros y ampliaciones en el área de distribución de Harpagus bidentatus, Glaucidium sanchezi, Attila spadiceus, Cyanolyca nana, Oreoscoptes montanus y Peucedramus taeniatus. Estas seis especies de aves fueron registradas en el bosque mesófilo de montaña del estado de Hidalgo, México. Dos de estas especies (G. sanchezi y C. nana son especies de distribución restringida, lo que eleva a tres el número de especies de distribución restringida en la zona. Esto enfatiza la importancia de esta región en la conservación de la diversidad de aves. Se discuten las implicaciones de estos nuevos registros en la obtención de inventarios completos de la avifauna de la región y en la conservación de su diversidad de aves.

Regional Contamination of Moravia (South-Eastern Czech Republic): Temporal Shift of Pb and Zn Loading in Fluvial Sediments

Czech Academy of Sciences Publication Activity Database

Matys Grygar, Tomáš; Sedláček, J.; Bábek, O.; Nováková, Tereza; Strnad, L.; Mihaljevič, M.

2012-01-01

Roč. 223, č. 2 (2012), s. 739-753 ISSN 0049-6979 R&D Projects: GA AV ČR IAAX00130801 Institutional research plan: CEZ:AV0Z40320502 Keywords : fluvial sediments * Pb * Zn * regional contamination Subject RIV: DD - Geochemistry Impact factor: 1.748, year: 2012

Influencia del uso de la tierra con cultivos de cacao, chakras y bosque primario, sobre la diversidad, almacenamiento de carbono y productividad en la Reserva de la Biosfera Sumaco, Ecuador.

OpenAIRE

Jadán Maza, Ángel Oswaldo

2013-01-01

La investigación se realizó en la Reserva de la Biosfera Sumaco, en la provincia del Napo, Republica del Ecuador. Se estudiaron siete sistemas de uso de la tierra: Chakras con y sin sombra, cultivos de cacao propagados por semilla con y sin sombra, cacao injertado con y sin sombra y bosque primario. Se evaluaron tres variables de respuesta: diversidad arbórea y arbustiva, almacenamiento-acumulación de carbono (C) y productividad, en los diferentes sistemas de usos de la tierra.

An inventory of published and unpublished fluvial-sediment data for California, 1956-70

Science.gov (United States)

Porterfield, George

1972-01-01

This inventory was prepared to provide a convenient reference to published and unpublished fluvial-sediment data for water years 1956-70, and updates substantially previous inventories. Sediment stations are listed in downstream order, and an alphabetical list of stations is also included. Figure 1 shows the approximate location of sediment stations in California. Most of the fluvial-sediment data in California were collected by the U.S. Geological Survey, under cooperative agreements with the following Federal, State, and local agencies: California Department of Water Resources, California Department of Navigation and Ocean Development, California Department of Fish and Game, Bolinas Harbor District, Monterey County Flood Control and Water Conservation District, Orange County Flood Control District, Riverside County Flood Control and Water Conservation District, San Diego County Department of Sanitation and Flood Control, San Luis Obispo County, San Mateo County, Santa Clara County Flood Control and Water District, Santa Cruz County Flood Control and Water Conservation District, Santa Cruz, city of, University of California, Ventura County Flood Control District, Forest Service, U.S. Department of Agriculture, Soil Conservation Service, U.S. Department of Agriculture, Corps of Engineers, U.S. Army, Bureau of Reclamation, U.S. Department of the Interior, National Park Service, U.S. Department of the Interior. This report was prepared by the Geological Survey under the general supervision of R. Stanley Lord, district chief in charge of water-resources investigations in California.

Floodplain forest succession reveals fluvial processes: A hydrogeomorphic model for temperate riparian woodlands.

Science.gov (United States)

Egger, Gregory; Politti, Emilio; Lautsch, Erwin; Benjankar, Rohan; Gill, Karen M; Rood, Stewart B

2015-09-15

River valley floodplains are physically-dynamic environments where fluvial processes determine habitat gradients for riparian vegetation. These zones support trees and shrubs whose life stages are adapted to specific habitat types and consequently forest composition and successional stage reflect the underlying hydrogeomorphic processes and history. In this study we investigated woodland vegetation composition, successional stage and habitat properties, and compared these with physically-based indicators of hydraulic processes. We thus sought to develop a hydrogeomorphic model to evaluate riparian woodland condition based on the spatial mosaic of successional phases of the floodplain forest. The study investigated free-flowing and dam-impacted reaches of the Kootenai and Flathead Rivers, in Idaho and Montana, USA and British Columbia, Canada. The analyses revealed strong correspondence between vegetation assessments and metrics of fluvial processes indicating morphodynamics (erosion and shear stress), inundation and depth to groundwater. The results indicated that common successional stages generally occupied similar hydraulic environments along the different river segments. Comparison of the spatial patterns between the free-flowing and regulated reaches revealed greater deviation from the natural condition for the braided channel segment than for the meandering segment. This demonstrates the utility of the hydrogeomorphic approach and suggests that riparian woodlands along braided channels could have lower resilience than those along meandering channels and might be more vulnerable to influences such as from river damming or climate change. Copyright © 2015 Elsevier Ltd. All rights reserved.

Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

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Jorien E Vonk

2016-08-01

Full Text Available Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C and molecular organic geochemistry (lignin, leaf waxes. High-resolution age models (137Cs, 210Pb of downcore lake sediment records (n=11 along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels. Comparison with earlier published Mackenzie River depth profiles shows that (i lake sediments reflect the riverine surface suspended load, and (ii hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

Using fecal profiles of bile acids to assess habitat use by threatened carnivores in the Maulino forest of central Chile Empleo del perfil de ácidos biliares fecales para evaluar uso del hábitat por carnívoros amenazados en el bosque maulino de Chile central

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CARLA GUERRERO

2006-03-01

Full Text Available The distribution and habitat use by carnivores can be assessed by studying their tracks or feces. If these methods are to be used confidently, they should not only unequivocally discriminate among species, but should also render the same patterns of spatial distributions. We assessed the fulfillment of these requirements with five carnivores inhabiting the Maulino forest of central Chile: Galictis cuja, Oncifelis guigna, Pseudalopex culpaeus, Pseudalopex griseus, and Puma concolor. Fecal bile acid thin layer chromatographic profiles were assessed, and shown to be species-specific, invariant within samples of a given individual and among individuals of a given species, but consistently different across species. The spatial distribution of feces in mixed stands of native forests and exotic pine plantations in the coastal Maule region of central Chile was compared with the expected distribution according to habitat offer, and also with the expected distribution based on earlier track records. The results revealed that Pseudalopex culpaeus makes extensive use of pine plantations; Oncifelis guigna prefers native forests, and Pseudalopex griseus thrives in pine plantations, native forests, and patches of native forest, in proportion to habitat availability. Results from scat distribution were similar to those obtained by tracks records. Feces and tracks were thus useful indicators of habitat use by carnivores, and could be used complementarily to study species with conservation problemsEl uso del hábitat por carnívoros puede ser examinado a partir de la distribución de sus huellas y fecas. Para que ambas aproximaciones sean usadas en forma segura y complementaria, ellas deberían no solamente discriminar inequívocamente entre especies, sino que también deberían entregar la misma información sobre los patrones de distribución espacial. Analizamos el cumplimiento de estos requisitos con cinco especies de carnívoros en el bosque maulino de Chile

Fluvial sedimentary styles and associated depositional environments in the buntsandstein west of river rhine in saar area and pfalz (F.R. Germany) and vosges (France)

Science.gov (United States)

Dachroth, Wolfgang

The Buntsandstein west of river Rhine in Saar area, Pfalz and Vosges consists of three fluvial magnacycles which are characterized by different associated non-alluvial environments. The stratigraphic sequence is divided by several unconformities reflecting tectonic movements which were connected with periods of extension of the depositional area. Two major phases and two minor events are recognized by the evaluation of the Pfalz unconformity and the Lothringen unconformity, and the Leuter unconformity and the Saar unconformity, respectively. The Lower Buntsandstein (including Zechstein) compries the first magnacycle and is built up of alluvial-fan deposits, fluvial braidplain sediments and marine to lagoonal deposits. Some aeolian sands as well as several palaeosols are also present. The palaeolandscape consists of alluvial fans seaming the margin of the basin and fluvial braidplains reaching from the toes of the fan belt to the centre of the depositional area which is occupied by a lagoonal sea that partially evolves into a playa-lake with progressive refreshment. The Middle Buntsandstein comprises the second magnacycle and is composed of an alternation of aeolian Dünnschichten and fluvial Felsbänke. The third facies are alluvial-fan deposits of palaeogeographically restricted distribution along the margins of the basin. The aeolian Dünnschichten originate in the marginal parts of chott-type depressions (in comparison with the recent Chott Djerid in Tunesia) where rising ground water moistens the dry sediments that are laid down on the playa floor and thus allows their enhanced preservation. In dry periods, wind-blown sand is spread out as plane sheets or as migrating wind ripple trains, or accumulates to barchanoid-type dunes that advance across the flat. Depending on supply of sand, all stages of transition between dune fields with only narrow interdune corridors between the ridges and interdune playas with isolated widely-spaced dunes are developed. The

VARIAÇÃO ESPACIAL E CONDICIONANTES DO ENTALHAMENTO FLUVIAL NA BACIA DO RIO GRANDE, SUL DE MINAS GERAIS

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Éric Andrade Rezende

2016-12-01

Full Text Available O presente trabalho pretende avaliar as variações no aprofundamento da drenagem na alta/média bacia do Rio Grande, sul de Minas Gerais. Para a mensuração do entalhamento fluvial (amplitude altimétrica em cada trecho dos canais fluviais foi utilizada a base ottocodificada em conjunto com o modelo digital de elevação SRTM/Topodata. A distribuição das classes de amplitude mostrou que na maior parte da alta/média bacia do Rio Grande o entalhamento fluvial situa-se entre 40 e 120 m. Valores superiores a 120 m concentram-se principalmente na Serra da Mantiqueira, junto às cabeceiras dos principais rios. O controle litológico sobre a distribuição das classes de amplitude é espacialmente restrito, o que sugere que a tectônica cenozoica é o principal fator controlador da intensidade da incisão fluvial. A boa correspondência entre classes de amplitude e falhas mapeadas indica a atuação de soerguimentos diferenciais entre blocos, com o consequente rebaixamento de níveis de base regionais nos blocos baixos. Esse controle é mais evidente na porção sul da área, com destaque para a zona de cisalhamento de Jesuânia (ENE. Nesse contexto, as áreas mais soerguidas são as porções da Serra da Mantiqueira que reúnem as principais concentrações de amplitudes superiores a 200 m. Mais ao norte merecem destaque as áreas com concentrações anômalas de amplitudes relativamente elevadas ao norte de Três Corações e na média/baixa bacia do Rio Jacaré. No primeiro caso um considerável soerguimento neocenozoico também deve ter ocorrido, enquanto no segundo as amplitudes mais elevadas aparentemente estão relacionadas à retração erosiva de um knickpoint com o consequente rejuvenescimento do relevo. A predominância de amplitudes menores (< 80 m na porção oriental, drenada por afluentes do alto Rio Grande, em relação à porção ocidental (sub-bacia do Rio Sapucaí aparenta estar relacionada à presença de soleiras quartz

Código del Consumidor y transporte fluvial en Loreto, San Martín y Ucayali. Análisis a dos años de su vigencia

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José Enrique Reátegui Ríos

2013-12-01

Full Text Available El transporte fluvial es una de las principales modalidades de transporte empleada en los departamentos de Loreto, San Martín y Ucayali. El principal problema que afecta al sector es el elevado nivel de informalidad que perjudica a sus usuarios, la mayoría de los cuales se encuentra en situación de pobreza o extrema pobreza. El Indecopi ha desarrollado acciones concretas con la finalidad de lograr una protección y una efectiva defensa de los derechos del consumidor, para lo cual, articula esfuerzos con otras instituciones para garantizar un servicio de transporte fluvial de calidad y seguro. El presente artículo presenta brevemente algunos datos sobre la prestación del servicio de transporte fluvial en los departamentos de Loreto, San Martín y Ucayali, la intervención del INDECOPI y algunas reflexiones respecto al rol que compete al Estado en este sector.

Fluvial sediment transport: Analytical techniques for measuring sediment load

International Nuclear Information System (INIS)

2005-07-01

Sediment transport data are often used for the evaluation of land surface erosion, reservoir sedimentation, ecological habitat quality and coastal sediment budgets. Sediment transport by rivers is usually considered to occur in two major ways: (1) in the flow as a suspended load and (2) along the bed as a bed load. This publication provides guidance on selected techniques for the measurement of particles moving in both modes in the fluvial environment. The relative importance of the transport mode is variable and depends on the hydraulic and sedimentary conditions. The potential user is directed in the selection of an appropriate technique through the presentation of operating principles, application guidelines and estimated costs. Techniques which require laboratory analysis are grab sample, pump sample, depth sample, point integrated and radioactive tracers. Techniques which will continuously record data are optical backscattering, nuclear transmission, single frequency acoustic and laser diffraction

Monitoreo de cambios en la densidad de cobertura forestal en bosque templado usando fotografías aéreas digitales de alta resolución

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José López García

2016-08-01

Full Text Available Se utilizaron series multitemporales de fotografías aéreas digitales de alta resolución de pequeño formato para evaluar los cambios en la densidad de cobertura forestal en un bosque templado. Una combinación de técnicas convencionales y adaptadas de fotogrametría y fotointerpretación fueron utilizadas para establecer un método específico de evaluación.  Este método ha sido probado en un periodo de doce años (1999-2011 en la zona núcleo de la Reserva de la Biósfera Mariposa Monarca, localizada en los estados de México y Michoacán, en México, usando mosaicos ortorectificados como mapas base para evaluar cambios bienales. Las imágenes fueron fotointerpretadas de manera tradicional marcando los cambios sobre acetatos, colocados sobre las imágenes impresas, creando así nuevos polígonos. Estos fueron transferidos directamente de los acetatos al ortomosaico a través de la pantalla de la computadora, usando al menos tres puntos de control, cumpliendo así con el principio de triangulación radial. El bosque fue separado en las siguientes clases de cobertura forestal: cerrada, semi-cerrada, semi-abierta, abierta y deforestada. La evaluación en la exactitud en la clasificación de densidad de cobertura fue estimada a través de muestreos en campo, empleando matrices de confusión, siendo del 95%. A partir de 2003, este método ha sido utilizado para determinar el pago por servicios ambientales. Dicho pago, junto con una gran interacción con las comunidades, se ha traducido en una reducción en la degradación forestal y la deforestación en la zona núcleo de la Reserva.

Diagnostic sedimentary structures of the fluvial-tidal transition zone – Evidence from deposits of the Rhine and Meuse

NARCIS (Netherlands)

Berg, J.H. van den; Boersma, J.R.; Gelder, A. van

2007-01-01

n mesotidal settings the transition of a coastal plain estuary to the river is marked by the change of a multiple ebb and flood channel configurationto a single channel system. At high river discharge fluvial processes operate, whereas in periods of low discharge the flow is complicated by a

The origin of dose distributions in fluvial sediments, and the prospect of dating single grains from fluvial deposits using optically stimulated luminescence

CERN Document Server

Olley, J M; Roberts, R G

1999-01-01

We examine the causes of the asymmetric distributions of dose observed from measurements of the optically stimulated luminescence emitted by small aliquots of fluvial quartz, and deduce that the asymmetry arises as a result of samples being composed of a mix of mainly well bleached grains with grains that were effectively unbleached at the time of deposition. We demonstrate that the shapes of the dose distributions can be used to assess the likelihood that aliquots consist only of grains that were well-bleached at the time of deposition. The more asymmetric the distribution, the greater the probability that the aliquots with the lowest dose most closely represent the true burial dose. Single grains with differing doses are present in each of the samples examined, and the population with the lowest dose gives an optical age consistent with the expected burial age. This result implies that the beta-dose heterogeneity in these deposits is small, and that the effects of micro-dosimetric variations on optical dati...

Relación entre las características del hábitat y la producción de individuos adultos de Dynastes hercules en relictos de bosque con diferente esfuerzo de caza

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Nohora Yolanda Ardila González

2006-01-01

que caracterizan estos tres componentes en dos relictos de bosque con diferente esfuerzo de caza. Fue observada una variación conjunta entre el ambiente con la densidad y porte de los individuos de las especies vegetales asociadas, donde se presenta una posible distribución agregada de estos recursos. Se encontró un microhábitat para escarabajos inmaduros con mejores condiciones en el relicto con menor esfuerzo de caza y una abundancia de adultos similar entre los dos relictos de bosque. Por otra parte, se obtuvo un bajo componente del hábitat relacionado con la producción de hembras y machos adultos. Se concluye que podría existir una compensación de individuos en el relicto con mayor esfuerzo de caza proveniente de otras subpoblaciones, y que el relicto con menor esfuerzo de caza podría funcionar como fuente de adultos. De esta manera, se plantea la hipótesis que las subpoblaciones entre relictos de la región podrían funcionar en un sistema fuentesumidero. Con la información generada en este estudio, información proveniente de sitios de cría y publicaciones relacionadas con el escarabajo hércules, se propone un modelo conceptual para la estimación de la producción de individuos adultos en las poblaciones locales.

Crecimiento y supervivencia de plántulas de cinco especies de Acacia (Fabaceae, que coexisten en bosques secos neotropicales de Argentina, en distintas condiciones de disponibilidad de luz y agua

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Paula Venier

2013-06-01

Full Text Available El establecimiento de la plántula es una de las etapas más riesgosas para las plantas, especialmente en zonas áridas y semiáridas donde la sequía y alta radiación solar influyen sobre su emergencia, desarrollo y supervivencia. Se evaluó en invernadero la supervivencia y variables de crecimiento en plántulas sometidas a estrés hídrico y a distintas condiciones de luz, en cinco especies de Acacia (A. aroma, A. caven, A. atramentaria, A. gilliesii y A. praecox que coexisten en los bosques xerófilos de Córdoba, Argentina. Aunque se encontraron diferencias entre las especies (F=5.66, p=0.001, todas tuvieron altos porcentajes de supervivencia en las distintas condiciones de luz y agua, sugiriendo que serían tolerantes al estrés hídrico y podrían establecerse bajo luz o sombra. Si bien todas las especies mejoraron el crecimiento con luz y sin estrés hídrico, A. aroma, A. caven y A. atramentaria mostraron una tendencia hacia un mayor crecimiento en la mayoría de las variables consideradas (F=41.9, p<0.0001; F=7.06, p<0.0001; F=53.59, p<0.0001. Estos resultados sumados a otros ya reportados indicarían una diferenciación de nichos regenerativos favoreciendo la coexistencia regional de estas especies en los bosques xerófilos de Córdoba.

Implicaciones sedimentológicas sobre el cambio en la cobertura del bosque de manglar en Boca Zacate, Humedal Nacional Térraba-Sierpe, Costa Rica

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Ana Margarita Silva Benavides

2015-09-01

Full Text Available Resumen:En los últimos sesenta años han ocurrido cambios en el Humedal Nacional Térraba-Sierpe, Costa Rica. Los cambios en la geomorfología costera están asociados a la erosión o acreción de sedimentos, lo que ha favorecido la eliminación de sectores de bosque o a la formación de bancos de sedimentos que han sido colonizados por árboles de mangle. El estudio se realizó en los sectores Bocón, Brujo e isla Coco en Boca Zacate, Humedal Nacional Térraba-Sierpe, Costa Rica, entre 2008-2013, cuyo objetivo consiste en analizar el aporte de sedimentos y las implicaciones en la cobertura del bosque de mangle en el sector de Boca Zacate. Es este estudio se realizó un análisis multitemporal de la morfología litoral con fotografías aéreas e imágenes satelitales de 1948, 1960, 1974, 1978, 1984, 1992 y 2011. Y además, se cuantificó la tasa de sedimentación mensual (g/cm2/día en los canales de los estuarios, la composición granulométrica y la concentración de elementos químicos en los sedimentos (mgL-1 en época seca y lluviosa durante los años de estudio. Los resultados indican que Boca Zacate ha mantenido en los últimos 60 años una tendencia hacia la erosión, perdiendo un 10.6 % de su espacio emergido entre 1948 y 2011 y aproximadamente un 8.9 % de su cobertura forestal; también ha experimentado una acreción en la zona de la isla Coco, uniéndose al continente por este sector. La tasa de sedimentación cuantificada en los esteros presentó diferencias con respecto al sitio y a la época. La mayor cantidad se presentó en el estero el Brujo y la menor cantidad en el estero Camíbar. Con respecto a la granulo-metría, el tipo de sedimento dominante es la arena, seguido por la arcilla y en menor cantidad el limo en todos los sitios de estudio. La mayor distribución de los elementos químicos corresponde al magnesio, calcio, potasio; mientras que el manganeso, hierro, aluminio, fósforo, zinc y cobre se encontraron en menor

Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios.

Science.gov (United States)

Mouri, Goro

2015-11-15

For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity

Predicting interwell heterogeneity in fluvial-deltaic reservoirs: Outcrop observations and applications of progressive facies variation through a depositional cycle

Energy Technology Data Exchange (ETDEWEB)

Knox, P.R.; Barton, M.D. [Univ. of Texas, Austin, TX (United States)

1997-08-01

Nearly 11 billion barrels of mobile oil remain in known domestic fluvial-deltaic reservoirs despite their mature status. A large percentage of this strategic resource is in danger of permanent loss through premature abandonment. Detailed reservoir characterization studies that integrate advanced technologies in geology, geophysics, and engineering are needed to identify remaining resources that can be targeted by near-term recovery methods, resulting in increased production and the postponement of abandonment. The first and most critical step of advanced characterization studies is the identification of reservoir architecture. However, existing subsurface information, primarily well logs, provides insufficient lateral resolution to identify low-permeability boundaries that exist between wells and compartmentalize the reservoir. Methods to predict lateral variability in fluvial-deltaic reservoirs have been developed on the basis of outcrop studies and incorporate identification of depositional setting and position within a depositional cycle. The position of a reservoir within the framework of a depositional cycle is critical. Outcrop studies of the Cretaceous Ferron Sandstone of Utah have demonstrated that the architecture and internal heterogeneity of sandstones deposited within a given depositional setting (for example, delta front) vary greatly depending upon whether they were deposited in the early, progradational part of a cycle or the late, retrogradational part of a cycle. The application of techniques similar to those used by this study in other fluvial-deltaic reservoirs will help to estimate the amount and style of remaining potential in mature reservoirs through a quicklook evaluation, allowing operators to focus characterization efforts on reservoirs that have the greatest potential to yield additional resources.

Dinámica de elementos en epífitos de un bosque altoandino de la Cordillera Oriental de Colombia

Directory of Open Access Journals (Sweden)

Caballero Rueda Luis Martín

1997-06-01

Full Text Available The reserves and transfer of bioelements were studied during two years in the epiphytic bryophytes and the bromeliad Tillandsia compacta in a high Andean forest in Guisquiza, La Calera, Cundinamarca in the Eastern Andes of Colombia. Epiphyte biomass in this forest is 3766 kg/ha, ofwhich bryophytes contribute 55% and T.compacta, 9.3%. In relation to their biomass, these epihyttes store high quantities of water and nutrients and intercept materials washed from foliage, making them important to consider in watershed management. There are no significant differences in epiphyte element composition between soll and trees, or between size categories of T. compacta. Trapping of heavy elements in particular may mitigate contamination problems in diverse components of the ecosystem. T.compacta appears especially important as a regulator of potassium transfer, and therefore of cation exchange capacity of the system. These properties permit the epiphytes to be dampers of high acidity and of excess concentrations of Al, Fe and Mn common in montant ecosystems, which can be observed in the dynamic model presented.En un estudio del bosque alto andino de la vereda Guisquiza, La Calera (Cundinamarca, se analizaron las reservas y transferencia de bioelementos en briófitos y Tillandsia compacta Grisebach (Bromeliaceae, durante dos años. Las epífitas tienen una biomasa de 3766 Kg/ha en el bosque'; de este valor los briófitos son el 55 % Y T.compacta el 9.3 %. Para esta biomasa tan pequeña, resultan almacenar altas cantidades de agua, nutrientes y ser interceptoras de materiales de lavado foliar que las hacen valiosas para los planes de manejo y ordenación de cuencas. No hay diferencias entre los valores de los elementos epífitos del suelo con respecto a los de los arboles; igualmente entre las categorfas de T.compacta. El trampeo de elementos especialmente, los pesados, disminuye los problemaspor intoxicación en los diversos componentes del ecosistema. T

Utilización de especies nativas del bosque seco para la recuperación del paisaje en el proceso de cierre del botadero a cielo abierto del distrito Las Lomas-Piura

OpenAIRE

Montoro Negrón, Barbara Elizabeth; Montoro Negrón, Barbara Elizabeth; Montoro Negrón, Barbara Elizabeth

2011-01-01

La presente investigación estudia la fragmentación del paisaje del distrito de Las Lomas en Piura, afectado por la existencia de un botadero a cielo abierto, y la posible restauración del paisaje durante el proceso de clausura. Para lo cual se estudiaron las especies vegetales nativas del bosque seco piurano seleccionando las más resistentes y útiles en el proceso de recuperación, las mismas que fueron colocadas paisajísticamente sobre la cobertura final. Este proceso denominado Fitorremediac...

A review on studies of the transport and the form of radionuclides in the fluvial environment

Energy Technology Data Exchange (ETDEWEB)

Matsunaga, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-06-01

The Japan Atomic Energy Research Institute has conducted studies with an aim to contribute to understanding the long-term behavior of atmospherically-derived radionuclides deposited on the ground. The present report reviews a series of studies among them which have especially dealt with the behavior of those radionuclides in a fluvial environment. The studies cited here include investigations of 1) the evaluation of the transport rate of the atmospherically-derived radionuclides from the ground via a river to the downstream areas where the affected water is consumed; 2) the physico-chemical form of the radionuclides in the fluvial environment. An investigation in the Kuji river watershed with {sup 137}Cs, {sup 210}Pb and {sup 7}Be has validated i) the importance of suspended particulate materials in the fluvial discharge of those radionuclides, and ii) a methodology to estimate the discharge of those radionuclides based on the regression analysis with the river water flow rate. From a viewpoint of their distribution between water and suspended particles, the form of radionuclides released by the Chernobyl accident in rivers and lakes in the vicinity of the Chernobyl Nuclear Power Plant were analyzed. As a result, a general reasonability and some cautions were suggested when commonly reported distribution ratios obtained in the laboratory and the different environment are applied to describe the partitioning of the radionuclides in specific natural environmental conditions. This experimental investigation in Chernobyl also revealed the role of natural dissolved organics in affecting the dissolution and transport of {sup 239,240}Pu, {sup 241}Am through complexation to form soluble species. Further, a chemical equilibrium model was applied to describe this complexation. The similar model was also applied for the behavior of iron and manganese (hydr)oxides in river recharged aquifers which can bear riverborne radionuclides and can influence their migration. The

A review on studies of the transport and the form of radionuclides in the fluvial environment

International Nuclear Information System (INIS)

Matsunaga, Takeshi

2001-06-01

The Japan Atomic Energy Research Institute has conducted studies with an aim to contribute to understanding the long-term behavior of atmospherically-derived radionuclides deposited on the ground. The present report reviews a series of studies among them which have especially dealt with the behavior of those radionuclides in a fluvial environment. The studies cited here include investigations of 1) the evaluation of the transport rate of the atmospherically-derived radionuclides from the ground via a river to the downstream areas where the affected water is consumed; 2) the physico-chemical form of the radionuclides in the fluvial environment. An investigation in the Kuji river watershed with 137 Cs, 210 Pb and 7 Be has validated i) the importance of suspended particulate materials in the fluvial discharge of those radionuclides, and ii) a methodology to estimate the discharge of those radionuclides based on the regression analysis with the river water flow rate. From a viewpoint of their distribution between water and suspended particles, the form of radionuclides released by the Chernobyl accident in rivers and lakes in the vicinity of the Chernobyl Nuclear Power Plant were analyzed. As a result, a general reasonability and some cautions were suggested when commonly reported distribution ratios obtained in the laboratory and the different environment are applied to describe the partitioning of the radionuclides in specific natural environmental conditions. This experimental investigation in Chernobyl also revealed the role of natural dissolved organics in affecting the dissolution and transport of 239,240 Pu, 241 Am through complexation to form soluble species. Further, a chemical equilibrium model was applied to describe this complexation. The similar model was also applied for the behavior of iron and manganese (hydr)oxides in river recharged aquifers which can bear riverborne radionuclides and can influence their migration. The obtained findings and the

Quality-Assurance Plan for the Analysis of Fluvial Sediment by the U. S. Geological Survey Kentucky Water Science Center Sediment Laboratory

National Research Council Canada - National Science Library

Shreve, Elizabeth A; Downs, Aimee C

2005-01-01

This report describes laboratory procedures used by the U. S. Geological Survey Kentucky Water Science Center Sediment Laboratory for the processing and analysis of fluvial sediment samples for concentration of sand and finer material...

Identifying the source of fluvial terrace deposits using XRF scanning and Canonical Discriminant Analysis: A case study of the Chihshang terraces, eastern Taiwan

Science.gov (United States)

Chang, Queenie; Lee, Jian-Cheng; Hunag, Jyh-Jaan; Wei, Kuo-Yen; Chen, Yue-Gau; Byrne, Timothy B.

2018-05-01

The source of fluvial deposits in terraces provides important information about the catchment fluvial processes and landform evolution. In this study, we propose a novel approach that combines high-resolution Itrax-XRF scanning and Canonical Discriminant Analysis (CDA) to identify the source of fine-grained fluvial terrace deposits. We apply this approach to a group of terraces that are located on the hanging wall of the Chihshang Fault in eastern Taiwan with two possible sources, the Coastal Range on the east and the Central Range on the west. Our results of standard samples from the two potential sources show distinct ranges of canonical variables, which provided a better separation ability than individual chemical elements. We then tested the possibility of using this approach by applying it to several samples with known sediment sources and obtain positive results. Applying this same approach to the fine-grained sediments in Chihshang terraces indicates that they are mostly composed of Coastal Range material but also contain some inputs from the Central Range. In two lowest terraces T1 and T2, the fine-grained deposits show significant Central Range component. For terrace T4, the results show less Central Range input and a trend of decreasing Central Range influences up section. The Coastal Range material becomes dominant in the two highest terraces T7 and T10. Sediments in terrace T5 appear to have been potentially altered by post-deposition chemical alteration processes and are not included in the analysis. Our results show that the change in source material in the terraces deposits was relatively gradual rather than the sharp changes suggested by the composition of the gravels and conglomerates. We suggest that this change in sources is related to the change in dominant fluvial processes that controlled by the tectonic activity.

Sistemas agroforestales como estrategia para el manejo de ecosistemas de Bosque seco Tropical en el suroccidente colombiano utilizando los sig

Directory of Open Access Journals (Sweden)

Nathaly de los Ángeles Mazo

2016-01-01

Full Text Available Los sistemas agroforestales son una alternativa para el manejo de zonas de bosque seco tropical de laderas intervenidas o en degradación. Sus beneficios se basan en el uso eficiente de los recursos, la productividad y la seguridad alimentaria de las comunidades rurales. Localizar lugares más aptos para dichos sistemas es un requisito en el proceso de extensión agrícola. Con este propósito, la utilización de modelos probabilísticos integrados con Sistemas de Información Geográfica (SIG permite identificar aquellas áreas potenciales para la implementación de nuevas tecnologías, de modo similar a la identificación de nichos de especies en estudios de biodiversidad. Siguiendo este enfoque, se utilizó el peso de la evidencia y la regresión logística para generar superficies indicativas de áreas adecuadas para implementar la agroforestería en el suroccidente colombiano.

Sistemas agroforestales como estrategia para el manejo de ecosistemas de Bosque seco Tropical en el suroccidente colombiano utilizando los SIG

Directory of Open Access Journals (Sweden)

Nathaly de los Ángeles Mazo

2016-01-01

Full Text Available Los sistemas agroforestales son una alternativa para el manejo de zonas de bosque seco tropical de laderas intervenidas o en degradación. Sus beneficios se basan en el uso eficiente de los recursos, la productividad y la seguridad alimentaria de las comunidades rurales. Localizar lugares más aptos para dichos sistemas es un requisito en el proceso de extensión agrícola. Con este propósito, la utilización de modelos probabilísticos integrados con Sistemas de Información Geográfica (SIG permite identificar aquellas áreas potenciales para la implementación de nuevas tecnologías, de modo similar a la identificación de nichos de especies en estudios de biodiversidad. Siguiendo este enfoque, se utilizó el peso de la evidencia y la regresión logística para generar superficies indicativas de áreas adecuadas para implementar la agroforestería en el suroccidente colombiano.

Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

DEFF Research Database (Denmark)

Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars

2007-01-01

We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between...... well-bleached and poorly bleached grains. It is especially important to investigate if the uncertainties assigned to individual estimates of dose adequately describe the observed variability in well-bleached dose distributions. We investigate this by quantifying the overdispersion in laboratory-bleached...

Sedimentological reservoir characteristics of the Paleocene fluvial/lacustrine Yabus Sandstone, Melut Basin, Sudan

Science.gov (United States)

Mahgoub, M. I.; Padmanabhan, E.; Abdullatif, O. M.

2016-11-01

Melut Basin in Sudan is regionally linked to the Mesozoic-Cenozoic Central and Western African Rift System (CWARS). The Paleocene Yabus Formation is the main oil producing reservoir in the basin. It is dominated by channel sandstone and shales deposited in fluvial/lacustrine environment during the third phase of rifting in the basin. Different scales of sedimentological heterogeneities influenced reservoir quality and architecture. The cores and well logs analyses revealed seven lithofacies representing fluvial, deltaic and lacustrine depositional environments. The sandstone is medium to coarse-grained, poorly to moderately-sorted and sub-angular to sub-rounded, arkosic-subarkosic to sublitharenite. On the basin scale, the Yabus Formation showed variation in sandstone bodies, thickness, geometry and architecture. On macro-scale, reservoir quality varies vertically and laterally within Yabus Sandstone where it shows progressive fining upward tendencies with different degrees of connectivity. The lower part of the reservoir showed well-connected and amalgamated sandstone bodies, the middle to the upper parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenetic changes such as compaction, cementation, alteration, dissolution and kaolinite clays pore fill and coat all have significantly reduced the reservoir porosity and permeability. The estimated porosity in Yabus Formation ranges from 2 to 20% with an average of 12%; while permeability varies from 200 to 500 mD and up to 1 Darcy. The understanding of different scales of sedimentological reservoir heterogeneities might contribute to better reservoir quality prediction, architecture, consequently enhancing development and productivity.

Radiocarbon constraints on the coupled growth of sediment and organic carbon reservoirs in fluvial systems

Science.gov (United States)

Torres, M. A.; Kemeny, P. C.; Fischer, W. W.; Lamb, M. P.

2017-12-01

Vast amounts of sediments are stored transiently in fluvial deposits as they move in rivers from source to sink. The timescale(s) of transient storage have the potential to set the cadence for biogeochemical reactions to occur in river sediments. However, the extent to which storage modulates the chemical composition of river sediments remains unclear. In case of the organic carbon (OC) cycle, transient sediment storage may leave an imprint in the radiocarbon (14C) content of riverine particulate OC (POC), offering a potential tool to trace the coupling of sediment storage and biogeochemical cycling in river systems. We investigated the modern and ancient budgets of sediments and POC in the Efi Haukadalsá River catchment in West Iceland to provide new empirical constraints on the role of sediment storage in the terrestrial OC cycle. This field site is attractive because the basaltic bedrock is free of rock-derived (i.e. "petrogenic") POC such that bulk 14C measurements can be interpreted more directly as constraints on catchment OC storage timescales. Additionally, Lake Haukadalsvatn at the outlet of the river catchment has captured sediment for nearly 13 ka, which offers a complementary record of the evolution of climate-sediment-OC linkages since deglaciation. New 14C measurements show that bulk POC in fine grained fluvial deposits within the Haukadalsá catchment is remarkably old (model ages between 1 and 10 ka). This evidence for "aged" POC in floodplain storage is consistent with previous measurements from Lake Haukadalsvatn, which show that POC is aged in the river system by thousands of years prior to deposition in the lake. Additionally, our estimate of the mean transit time of sediments through the river system matches the millennial-scale reservoir age of riverine POC derived from 14C, which implies a tight coupling between sediment storage and the OC cycle. We interpret the long-term increase in the 14C reservoir age of riverine POC over the last 10 ka

Diversidad florística arbórea y su relación con el suelo en un bosque pluvial tropical del chocó biogeográfico

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Harley Quinto Mosquera

2014-12-01

Full Text Available El objetivo del presente estudio fue determinar la composición y diversidad florística arbórea a escala local en un bosque del Chocó biogeográfico, una de las regiones más lluviosas del mundo, y su relación con las características del sitio. Se emplearon dos parcelas de una hectárea, en las cuales se determinó la composición y diversidad de árboles con DAP > 10 cm y se relacionaron con los nutrientes del suelo, la topografíay el espacio. No se presentaron diferencias significativas entre las parcelas para las variables estructurales y de diversidad estudiadas, con valores de abundancia de 640 y 716 individuos/ha yde riqueza de 174 y 223 especies/ha.Nuestros resultados soportan la hipótesis de hiperdominancia de unos pocos grupos biológicos en los bosques húmedos tropicales. Ladiversidad arbórea a escala local se relacionó significativamente con algunas condiciones edáficas.Se presentó asociación positiva de la diversidad con el aluminio del suelo, y negativa con la topografía.No obstante, solamente un 37% de la variación en la composición florística fue explicada por las variables espaciales y ambientales (topográficas y edáficas. Por ello, aparentemente la distribución de las especies a escala local parece estar gobernada principalmente por procesos aleatorios o biológicos (como la limitación en dispersión, conforme lo propone la teoría neutral. El papel de las adaptaciones específicas al hábitat (teoría del nicho pareciera ser limitado.

Fluvial depositional environment evolving into deltaic setting with marine influences in the buntsandstein of northern vosges (France)

Science.gov (United States)

Gall, Jean-Claude

The Buntsandstein in the Northern Vosges (France) originates mainly in an inland braidplain fluvial environment which passes in the upper part of the sequence into deltaic milieu in the coastal plain along the border of the sea, with the continental environment finally being drowned with the transgression of the shallow sea. The fluvial sedimentation is characterized by the presence of two facies throughout the Buntsandstein : channel facies and overbank plain facies. The channel facies comprises sandy and conglomeratic deposits forming within active streams by strong currents, whereas the overbank plain facies is built up of silty-clayey sandstones or silt/clay originating in stagnant water in abandoned watercourses, ponds, pools and puddles. The significance of particularly the floodplain sediments is subjected to considerable changes throughout the Buntsandstein sequence. There are all stages of transition between overbank plain deposits being only preserved in ghost-like facies as reworked clasts due to effective secondary removal of primarily occasionally formed suspension fines, and an abundance of autochthonous floodplain sediments in the depositional record resulting from favourable conditions of primary origin and secondary preservation. Reworked ventifacts within fluvial channel sediments testify to subordinate aeolian influences in the alluvial plain, with reasonable reworking, however, having removed all in situ traces of wind activity. Declining aridity of palaeoclimate towards the top is indicated by the appearance of violet horizon palaeosols in the Zone-Limite-Violette and the Couches intermédiaires being accompanied by Bröckelbank carbonate breccias originating from concentration of reworked fragments of pedogenic carbonate nodules. Biogenic traces are in the lower part of the sequence mainly present as Planolites burrows in the finer-grained sediments. Palaeosalinities as revealed from boron contents indicate progressively increasing

Using a Geospatial Model to Relate Fluvial Geomorphology to Macroinvertebrate Habitat in a Prairie River—Part 1: Genus-Level Relationships with Geomorphic Typologies

Directory of Open Access Journals (Sweden)

Anna G. N. Meissner

2016-01-01

Full Text Available Modern river ecosystems undergo constant stress from disturbances such as bank stabilization, channelization, dams, and municipal, agricultural, and industrial water use. As these anthropogenic water requirements persist, more efficient methods of characterizing river reaches are essential. Benthic macroinvertebrates are helpful when evaluating fluvial health, because they are often the first group to react to contaminants that can then be transferred through them to other trophic levels. Hence, the purpose of this research is to use a geospatial model to differentiate instream macroinvertebrate habitats, and determine if the model is a viable method for stream evaluation. Through the use of ArcGIS and digital elevation models, the fluvial geomorphology of the Qu’Appelle River in Saskatchewan (SK was assessed. Four geomorphological characteristics of the river were isolated (sinuosity, slope, fractal dimension, and stream width and clustered through Principle Component Analysis (PCA, yielding sets of river reaches with similar geomorphological characteristics, called typologies. These typologies were mapped to form a geospatial model of the river. Macroinvertebrate data were aligned to the locations of the typologies, revealing several relationships with the fluvial geomorphology. A Kruskal-Wallis analysis and post hoc pairwise multiple comparisons were completed with the macroinvertebrate data to pinpoint significant genera, as related to the geospatial model.

Controles fluviales del Rio Cauca en la región de La Mojana.

OpenAIRE

Posada García, Lilian; Rhenals Garrido, Remberto Luis

2006-01-01

Se realiza un análisis de fotografías aéreas, imágenes de satélite y cartografía de diferentes años que permiten identificar procesos importantes de divagación, erosión y sedimentación de la zona estudiada. La variación con el tiempo de las formas del canal (islas y barras), la aparición de complejos de orillares, madreviejas (canales abandonados y sedimentados), canales abandonados, cambios de curso del canal principal, entre otros procesos muestran la gran dinámica fluvial del sistema....

Dominant mechanisms for the delivery of fine sediment and phosphorus to fluvial networks draining grassland dominated headwater catchments.

Science.gov (United States)

Perks, M T; Owen, G J; Benskin, C McW H; Jonczyk, J; Deasy, C; Burke, S; Reaney, S M; Haygarth, P M

2015-08-01

Recent advances in monitoring technology have enabled high frequency, in-situ measurements of total phosphorus and total reactive phosphorus to be undertaken with high precision, whilst turbidity can provide an excellent surrogate for suspended sediment. Despite these measurements being fundamental to understanding the mechanisms and flow paths that deliver these constituents to river networks, there is a paucity of such data for headwater agricultural catchments. The aim of this paper is to deduce the dominant mechanisms for the delivery of fine sediment and phosphorus to an upland river network in the UK through characterisation of the temporal variability of hydrological fluxes, and associated soluble and particulate concentrations for the period spanning March 2012-February 2013. An assessment of the factors producing constituent hysteresis is undertaken following factor analysis (FA) on a suite of measured environmental variables representing the fluvial and wider catchment conditions prior to, and during catchment-wide hydrological events. Analysis indicates that suspended sediment is delivered to the fluvial system predominantly via rapidly responding pathways driven by event hydrology. However, evidence of complex, figure-of-eight hysteresis is observed following periods of hydrological quiescence, highlighting the importance of preparatory processes. Sediment delivery via a slow moving, probably sub-surface pathway does occur, albeit infrequently and during low magnitude events at the catchment outlet. Phosphorus is revealed to have a distinct hysteretic response to that of suspended sediment, with sub-surface pathways dominating. However, high magnitude events were observed to exhibit threshold-like behaviour, whereby activation and connection of usually disconnected depositional zones to the fluvial networks results in the movement of vast phosphorus fluxes. Multiple pathways are observed for particulate and soluble constituents, highlighting the

Toward the Validation of Depth-Averaged Three Dimensional, Rans Steady-State Simulations of Fluvial Flows at Natural Scale

Science.gov (United States)

Mateo Villanueva, P. A.; Hradisky, M.

2010-12-01

Simulations of fluvial flows are strongly influenced by geometric complexity and overall uncertainty on measured flow variables, including those assumed to be well known boundary conditions. Often, 2D steady-state models are used for computational simulations of flows at the scale of natural rivers. Such models have been successfully incorporated in iRIC (formerly MD_SWMS), one of the widely used quasi-3D CFD solvers to perform studies of environmental flows. iRIC aids in estimating such quantities as surface roughness and shear stress, which, in turn, can be used to estimate sediment transport. However, the computational results are inherently limited in accuracy because of restricting the computations to 2D, or quasi-3D, space, which can affect the values of these predictions. In the present work we perform computer-based simulations of fluvial flows using OpenFOAM, a free, open source fully 3D CFD software package, and compare our results to predictions obtained from iRIC. First, we study the suitability of OpenFOAM as the main CFD solver to analyze fluvial flows and validate our results for two well documented rectangular channel configurations: the first case consists of a large aspect-ratio channel (ratio of depth over width 0.017, ratio of depth over length 0.0019) with a rectangular obstacle mounted at the bottom wall; the second case involves a large aspect-ratio channel (ratio of depth over width 0.1, ratio of depth over length 0.0025) with cubic obstacles mounted at the lower wall (one obstacle) and upper wall (two obstacles). Secondly, we apply our model to simulation or river at natural scale and compare our results to the output obtained from iRIC to quantify the differences in velocity profiles and other flow parameters when comparable solution techniques are used. Steady-state, RANS k-epsilon models are employed for all simulations.

Dynamics of treefall gaps in a harvested forest in Misiones, Northern Argentine Dinámica de claros artificiales en un bosque aprovechado en Misiones, noreste de Argentina

Directory of Open Access Journals (Sweden)

Nardia Maria Luján Bulfe

2010-12-01

Full Text Available

This work evaluates the diameter growth of trees species of artificial gaps per ecological groups in a harvested forest considering two systems of harvest. The study was carried out in the Reserva de Biósfera Yabotí, in Misiones, Argentina. Fifteen permanent plots were established, each one with 4 hectares with effective area of measurement of one hectare. The three treatments were: conventional logging, reduced impact logging and control plot. All trees larger than 10 cm of diameter at breast height (DBH were measured, before (1998 and after the harvest (2006. Eighty-five species were registered. The average DBH diameter growth for all species was 0.41 cm yr-1 in the gap area, and 0.31 cm yr-1 for the control plot. The average diameter growth was 0.36 cm yr-1 for the reduced impact logging and 0.42 cm yr-1 for the conventional logging. In forests with high diversity, ecological groups are an important tool for the management and conservation. The reduced impact logging would be considered a less aggressive alternative for the forests in this region. 

doi: 10.4336/2010.pfb.30.64.311

Este trabajo evalúa el crecimiento diamétrico de especies arbóreas clasificadas en grupos ecológicos dentro de claros artificiales en un bosque estacional semideciduo aprovechado considerando dos sistemas de cosecha. El estudio fue desarrollado en la Reserva de Biosfera Yabotí, Misiones, Argentina. Se instalaron 15 parcelas permanentes, de cuatro hectáreas cada una, con un área efectiva de medición de una hectárea. Los tratamientos fueron tres: cosecha convencional, cosecha de impacto reducido y parcela testigo. Se registraron todos los ejemplares arbóreos mayores a 10 cm de diámetro a la altura del pecho (DAP antes (1998 y después de la cosecha (2006. La riqueza florística alcanzó un número de 85 especies. Para el conjunto de especies el crecimiento diamétrico promedio fue de 0,41 cm año-1 en área de claro y de 0,31 cm.año-1 en �

Characterization of a fluvial aquifer at a range of depths and scales: the Triassic St Bees Sandstone Formation, Cumbria, UK

Science.gov (United States)

Medici, Giacomo; West, L. J.; Mountney, N. P.

2018-03-01

Fluvial sedimentary successions represent porous media that host groundwater and geothermal resources. Additionally, they overlie crystalline rocks hosting nuclear waste repositories in rift settings. The permeability characteristics of an arenaceous fluvial succession, the Triassic St Bees Sandstone Formation in England (UK), are described, from core-plug to well-test scale up to 1 km depth. Within such lithified successions, dissolution associated with the circulation of meteoric water results in increased permeability ( K 10-1-100 m/day) to depths of at least 150 m below ground level (BGL) in aquifer systems that are subject to rapid groundwater circulation. Thus, contaminant transport is likely to occur at relatively high rates. In a deeper investigation (> 150 m depth), where the aquifer has not been subjected to rapid groundwater circulation, well-test-scale hydraulic conductivity is lower, decreasing from K 10-2 m/day at 150-400 m BGL to 10-3 m/day down-dip at 1 km BGL, where the pore fluid is hypersaline. Here, pore-scale permeability becomes progressively dominant with increasing lithostatic load. Notably, this work investigates a sandstone aquifer of fluvial origin at investigation depths consistent with highly enthalpy geothermal reservoirs ( 0.7-1.1 km). At such depths, intergranular flow dominates in unfaulted areas with only minor contribution by bedding plane fractures. However, extensional faults represent preferential flow pathways, due to presence of high connective open fractures. Therefore, such faults may (1) drive nuclear waste contaminants towards the highly permeable shallow (< 150 m BGL) zone of the aquifer, and (2) influence fluid recovery in geothermal fields.

Fluvial sediments characterization of Hornád river in its chosen parts (preliminary study

Directory of Open Access Journals (Sweden)

Stela Hanigovská

2008-12-01

Full Text Available Knowledge of main river sedimentary characteristics is very important source of information for next study or potentialcommercial usage of fluvial sediments. In paper is shown characterization of sediment distribution in chosen part of the river Hornád.Three main facial types were studied and described – gravel, sand and clay. Model created in this study shows that Hornád is a riverwith predominant gravel transport. This model also shows a sufficient amount of gravel for commercial use in some parts of the river.

Controls on fluvial metamorphosis during global warming at the Paleocene-Eocene boundary (56 Ma) in Spain: extreme droughts, extreme floods or both?

Science.gov (United States)

Castelltort, Sebastien; Chen, Chen; Guerit, Laure; Foreman, Brady; Paola, Chris; Adatte, Thierry

2017-04-01

How does global warming change the frequency and intensity of extreme weather events? The response to this question is partly preserved in the geological record. 56 Ma ago, global temperatures increased during the Paleocene-Eocene Thermal Maximum (PETM), leading to a major biotic turnover, but how this event affected the nature of extreme events remains unknown. On several continents, fluvial systems with sinuous channels within fine-grained floodplains suddenly transformed at the P-E boundary into apparently coarser-grained braid plains with frequent lateral migrations, washing their muddy floodplains to the seas. This landscape transformation has been related to aridification and intensification of precipitation allowing transport of coarser material as a result of P-E global warming, with important implications for predicting the consequences of current global change. Here we test this hypothesis by quantifying the magnitude of grain size change and flow depth at a representative P-E locality in Northern Spain. We find that the size of pebbles in transport and flow depth remained similar to, or even smaller than, pre-PETM conditions. This suggests that, if more seasonal and extreme precipitation occurred, they are not necessarily borne out in the predicted deeper flow depths and coarser grain sizes, but rather trigger a shift to multiple active channels. However, an alternative or complementary explanation may rest in pollen data found in coeval marine records and which document a dramatic vegetation shift from permanent conifer forests prior to the crisis into periodic vegetation in brief periods of rain during the hyperthermal episode. Such change induced by long periods of intense droughts, could have enhanced erodibility of channel banks by decreasing root-controlled cohesion of fine-grained floodplains and interfluves, promoting their lateral mobility and the observed fluvial metamorphosis. Thus, although water is regarded as the main agent sculpting

Conocimientos [matemáticos] mapuche1 desde la perspectiva de los educadores tradicionales de la comuna de El Bosque

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Pilar-Alejandra Peña-Rincón

2016-02-01

Full Text Available This paper presents a preview of an investigation aimed at identifying and systematizing some mapuche [mathematical] knowledge. The conceptual references are taken from Ethnomathematics defined by D'Ambrosio (2008 and the cross-cultural activities defined by Bishop (1999. The methodological reference is given by the Collaborative Research (Boavida y Ponte, 2002 and some elements of the Inductive Intercultural Method (Gasché, 2008. The team of co-researchers is composed of the some members of Indigenous Peoples Program of a municipality of Santiago, and members of research group about Ethnomathematics of a particular university. This text presents the research project and some partial results in relation to the space-time location according to the mapuche worldview: the sun is the central reference for the space location and for the time location over one day and over the years; whereas the moon shows the time location over larger cycles within one year (such as the moon cycles by themselves. The results will be incorporated into the educational area of the Indigenous Peoples Program of the municipality El Bosque.

Factores ambientales asociados con la preferencia de hábitat de larvas de tricópteros en cuencas con bosque seco tropical (Tolima, Colombia

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Jesús M. Vásquez-Ramos

2014-04-01

Full Text Available Los ríos de bosques secos tropicales están amenazados en todo el mundo, y en Suramérica son una de las prioridades en términos de conservación. En este estudio se determinó la influencia de variables ambientales (por ejemplo precipitación y la vegetación ribereña sobre las comunidades del orden Trichoptera en cuatro sustratos (roca, grava, arena y hojarasca en las cuencas Opia y Venadillo (Tolima, Colombia. En cada río, en dos segmentos de 100m (uno a ~550 y otro a ~250msnm, fueron evaluados los sustratos mencionados anteriormente. Se realizaron análisis físico-químicos, y se aplicó el índice QBR (calidad del bosque de ribera en ambos ríos. Se recolectaron 6 282 larvas, pertenecientes a 11 familias y 22 géneros, que representan el 73.30% y 43.13% de la fauna Trichoptera registrada en Colombia, respectivamente. Las familias más abundantes fueron Hydropsychidae (49.86% y Philopotamidae (25.44%. Los géneros Smicridea, Chimarra, Protoptila, Neotrichia y Leptonema fueron comunes en periodos de baja y alta precipitación. Las asociaciones de tricópteros no mostraron diferencias significativas a nivel de sustrato. Los principales factores que determinaron la composición, riqueza y abundancia de tricópteros fueron la estacionalidad y la vegetación de ribera. Sin embargo, las localidades situadas a mayor altitud y no urbanizadas, ofrecen mayor variedad de sustratos y mayor riqueza de géneros. Nuestros resultados indican que a futuro las larvas de Trichoptera constituyen un elemento biótico relevante en los ecosistemas dulceacuícolas, debido a que son sensibles a disturbios ambientales. Por ende, sugerimos el uso de los tricópteros para biomonitoreo en ríos tropicales. La implementación de estos estudios es urgente, teniendo en cuenta que la degradación de los ecosistemas dulceacuícolas tiende a ser intensa y persistente.

Limites de la cooperación internacional ambiental: el caso del Programa Piloto para la Protección de los Bosques Tropicales de Brasil

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Elimar Pinheiro do Nascimento

2010-05-01

Full Text Available Más allá de sus múltiples éxitos, el análisis de las alianzas verdes del Programa Piloto para la Protección de los Bosques Tropicales de Brasil (PPG7, así como de los conflictos presentes en su creación y ejecución, de los resultados alcanzados y de las circunstancias de su finalización, muestra que el PPG7 contribuyó poco a la conservación del bosque, al fortalecimiento institucional de la región amazónica y a su desarrollo sostenible. Esto debido a su concepción neoliberal y limitaciones institucionales. Aprisionado por el localismo, entre los riesgos y las oportunidades creadas por el agronegocio para la Amazonía, el PPG7 olvidó el papel destacado del Estado nacional en las regiones en desarrollo. Una eficaz cooperación internacional al ambiente requerirá de nuevos conceptos de efectividad, de una cooperación menos hegemónica y un fortalecimiento del movimiento por la sustentabilidad. Beyond its many achievements, an analysis of the green alliances of the Pilot Program for the Protection of the Tropical Forests of Brazil (PPG7, Portuguese acronym, as well as the conflicts present in its creation and implementation, of the results achieved, and of the circumstances in which it came to an end, demonstrate that the PPG7 contributed little to the conservation of the forest, the institutional strengthening of the Amazon region, or its sustainable development. This is due to its neoliberal conception and institutional limitations. Trapped in the local, between risks and opportunities created by agribusiness in the Amazon, the PPG7 forgot the outstanding role of the national state in developing regions. Effective international cooperation on the environment will require new concepts of effectiveness, cooperation that is less top-down, and strengthening of the sustainability movement.

Restauración ecológica de bosques tropicales en Costa Rica: efecto de varios modelos en la producción, acumulación y descomposición de hojarasca

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Danielle Celentano

2011-09-01

Full Text Available Estrategias de restauración tienen el potencial de acelerar el restablecimiento del ciclo de nutrientes en áreas degradadas. En este estudio, se evaluó la producción de hojarasca, su acumulación y descomposición bajo tres tratamientos: plantación (toda la superficie plantada; islas (árboles sembrados en parches de tres tamaños y testigo (regeneración natural. También se compararon bosques secundarios jóvenes (7-9 años. Los tratamientos fueron establecidos en parcelas de 50x50m en junio 2004 en seis sitios en el sur de Costa Rica. Las especies introducidas fueron dos maderables (Terminalia amazonia y Vochysia guatemalensis intercaladas con dos fijadoras de nitrógeno (Erythrina poeppigiana e Inga edulis. La producción total de hojarasca en la plantación y bosque secundario no difirió significativamente, fue mayor que en las islas y el testigo. La plantación presentó mayor acumulación de hojarasca sobre el suelo. Los resultados indican una gran variabilidad entre los sitios. Ambas estrategias de restauración activas aceleraron la producción y acumulación de hojarasca en comparación con la regeneración. No obstante, eso no implica la restauración del ciclo de nutrientes. La elevada acumulación de hojarasca sobre el suelo indica baja tasa de descomposición y de retorno de nutrientes al suelo.

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir, Class I

Energy Technology Data Exchange (ETDEWEB)

Bou-Mikael, Sami

2002-02-05

This report demonstrates the effectiveness of the CO2 miscible process in Fluvial Dominated Deltaic reservoirs. It also evaluated the use of horizontal CO2 injection wells to improve the overall sweep efficiency. A database of FDD reservoirs for the gulf coast region was developed by LSU, using a screening model developed by Texaco Research Center in Houston. The results of the information gained in this project is disseminated throughout the oil industry via a series of SPE papers and industry open forums.

Fluvial fluxes of natural radium isotopes and dissolved barium for Ubatuba embayments, Sao Paulo

International Nuclear Information System (INIS)

Sousa, Keila Cristina Pinheiro Marchini de

2008-01-01

Radium isotopes are among the most important isotopes in the environment from both radioprotection and geo-hydrological points of view. They are also a powerful tool for studying geohydrological processes and have been used intensively as tracers of groundwater sources that discharge into the coastal ocean.The complex exchange of fluvial, subsurface and seawater within a coastal area directly affects global biogeochemical cycles. Environmental scientists have few tools to accurately quantify such processes and must therefore rely on various tracer techniques. Radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers. In this study we determined the fluvial fluxes of the radium isotopes and dissolved barium for Ubatuba embayments, northernmost part of Sao Paulo Bight. The research work was carried out from April/ 2007 to August/ 2007 and covered 17 small rivers sources that belong to the major surface draining system of such coastal area. During this period of investigation, groundwater samples were also collected from 10 sources available in this coastal region. Activity concentrations of 223 Ra in riverine waters discharging to Ubatuba and Caraguatatuba embayments varied from -1 to 335 mBq 1000L -1 (in Cocanha River), while 224 Ra concentrations ranged from 17 mBq 100L -1 to 7270 mBq 100L -1 . Activity concentrations up to 1424 mBq 100L -1 were observed for 226 Ra in riverine waters, while 228 Ra concentrations varied from 1412 mBq 100L -1 to 4058 mBq 100L -1 . Groundwater activity concentrations of 223 Ra varied from 1 mBq 100L -1 to 126 mBq 100L -1 , while 224 Ra ranged from 118 mBq 100L -1 to 3701 mBq 100L -1 . 223 Ra/ 224 Ra activity ratios up to 0.7x10 -1 and 0.2 were observed in riverine and groundwater, respectively. For 226 Ra groundwater activity concentrations

Year-round variations in the fluvial transport load of particulate 137Cs in a forested catchment affected by the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Takeshi Matsunaga; Takahiro Nakanishi; Mariko Atarashi-Andoh; Erina Takeuchi; Kotomi Muto; Katsunori Tsuduki; Syusaku Nishimura; Jun Koarashi; Shigeyoshi Otosaka; Tsutomu Sato

2016-01-01

Particulate 137 Cs was collected from stream water for 2 years to assess the long-term trend of 137 Cs discharge from a forest after the Fukushima Nuclear Power Plant accident. A seasonal increase in the fluvial transport load of particulate 137 Cs in suspended solids (SS) was observed in July-October when rainfall was abundant. The 137 Cs load was controlled by the SS load. This control was attributed to cesium affinity for phyllosilicate clay minerals as verified by the low extractability of particulate 137 Cs. These findings indicate the fluvial particulate 137 Cs load is significantly related to the climate and geomorphological features of Japan. (author)

Human impacts on fluvial systems - A small-catchment case study

Science.gov (United States)

Pöppl, Ronald E.; Glade, Thomas; Keiler, Margreth

2010-05-01

Regulations of nearly two-thirds of the rivers worldwide have considerable influences on fluvial systems. In Austria, nearly any river (or) catchment is affected by humans, e.g. due to changing land-use conditions and river engineering structures. Recent studies of human impacts on rivers show that morphologic channel changes play a major role regarding channelization and leveeing, land-use conversions, dams, mining, urbanization and alterations of natural habitats (ecomorphology). Thus 'natural (fluvial) systems' are scarce and humans are almost always inseparably interwoven with them playing a major role in altering them coincidentally. The main objective of this study is to identify human effects (i.e. different land use conditions and river engineering structures) on river bed sediment composition and to delineate its possible implications for limnic habitats. The study area watersheds of the 'Fugnitz' River (~ 140km²) and the 'Kaja' River (~ 20km²) are located in the Eastern part of the Bohemian Massif in Austria (Europe) and drain into the 'Thaya' River which is the border river to the Czech Republic in the north of Lower Austria. Furthermore the 'Thaya' River is eponymous for the local National Park 'Nationalpark Thayatal'. In order to survey river bed sediment composition and river engineering structures facies mapping techniques, i.e. river bed surface mapping and ecomorphological mapping have been applied. Additionally aerial photograph and airborne laserscan interpretation has been used to create land use maps. These maps have been integrated to a numerical DEM-based spatial model in order to get an impression of the variability of sediment input rates to the river system. It is hypothesized that this variability is primarily caused by different land use conditions. Finally river bed sites affected by river engineering structures have been probed and grain size distributions have been analyzed. With these data sedimentological and ecological

What can we learn from fluvial incision in high mountains?

Science.gov (United States)

Fuchs, Margret; Gloaguen, Richard; Krbetschek, Matthias

2013-04-01

High and actively deforming mountain ranges attract the attention of geoscientists as they provide natural laboratories of fast evolving process-response systems. Tectonic compressional settings, often linked to perpendicular extension, control the topographic growth and hence, erosion, transport pathways and sedimentation. High altitude differences within short horizontal distances promote material re-organisation and high rates of surface processes. Furthermore, high mountains constitute orographic barriers that affect atmospheric circulations as well as host different climate regimes similar to those of widely separated latitudinal belts. Both cause a high sensitivity of surface processes to changes in climatic conditions. However, feedbacks between climatic and tectonic forcing are complex. Additionally, the dominance of one or the other varies in space and also over time, inheriting various traces of the paleo-morphodynamic conditions to the subsequent process regimes. To unravel the forces driving the evolution of relief in active mountains, numerous studies employ the drainage network of the corresponding mountains as a proxy of landscape evolution. Especially the rates of river incision provide a powerful tool to characterize the surface response and infer causes behind it. Several parameters of river incision are available to describe the fluvial incision at individual sites (e.g. terrace incision rates), along the river course (e.g. longitudinal river profiles, Hack index) and in its perpendicular dimension (e.g. valley cross sections, valley shape ratios). But they require careful interpretation. They are sensitive to both, climatic and tectonic forcing. Therefore, the synopsis of such indices for fluvial incision is essential to evaluate the role of climatic versus tectonic forcing. Here, we use the Panj river system, the major river draining the Pamir mountains of Central Asia, as an example. The Panj experiences high altitude changes of more than 4000

Do river channels decrease in width downstream on Distributive Fluvial Systems? An evaluation of modern mega-fans

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Espinoza, T. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

2014-12-01

Recent studies on aggradational continental sedimentary basins globally show that fluvial deposits in most modern sedimentary basins are dominated Distributive Fluvial Systems (DFS). DFS's are identified by: (1) pattern of channels and floodplain deposits that radiate outward from an apex located where the river enters the sedimentary basin, (2) deposition where an alluvial system becomes unconfined upon entering the sedimentary basin, (3) broadly fan shaped deposit that is convex upward across the DFS and concave upward down-fan, and (4) if the DFS is incised, an intersection point above which the alluvial system is held in an incised valley and below which it distributes sediment across an active depositional lobe. Several papers about DFS hypothesized that rivers on DFS decrease in size down-fan. We are testing this hypothesis through evaluation of LANDSAT and STRM data from large DFS described by Hartley et al (2010). We use ArcGIS to: (1) open the images and merge them together if there are more than one image corresponding to the DFS being studied, (2) use a Maximum Likelihood Analysis in six classes to segment different features on the DFS (e.g. exposed sands, water, vegetation, and other fan environments), (3) isolate the classes that correspond to the active channel belt (e.g., exposed sand bars and water), (4) divide the active channel belt into 1000 m long sections, (5) determine the area of active channel belt in each section, and (6) calculate the average width of the river in each section (e.g., W = area/1000m). We present our result for each DFS river on a graph that shows the change in width downstream. Our final product will be a dataset that contains width versus distance down-fan from the apex for as many of the large DFS from Hartley et al (2010) as possible. If the hypothesis is supported, the decrease in width could have a substantial predictive significance on sandstone geometry in fluvial successions.

Significance of Thermal Fluvial Incision and Bedrock Transfer due to Ice Advection on Greenland Ice Sheet Topography

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Crozier, J. A.; Karlstrom, L.; Yang, K.

2017-12-01

Ice sheet surface topography reflects a complicated combination of processes that act directly upon the surface and that are products of ice advection. Using recently-available high resolution ice velocity, imagery, ice surface elevation, and bedrock elevation data sets, we seek to determine the domain of significance of two important processes - thermal fluvial incision and transfer of bedrock topography through the ice sheet - on controlling surface topography in the ablation zone. Evaluating such controls is important for understanding how melting of the GIS surface during the melt season may be directly imprinted in topography through supraglacial drainage networks, and indirectly imprinted through its contribution to basal sliding that affects bedrock transfer. We use methods developed by (Karlstrom and Yang, 2016) to identify supraglacial stream networks on the GIS, and use high resolution surface digital elevation models as well as gridded ice velocity and melt rate models to quantify surface processes. We implement a numerically efficient Fourier domain bedrock transfer function (Gudmundsson, 2003) to predict surface topography due to ice advection over bedrock topography obtained from radar. Despite a number of simplifying assumptions, the bedrock transfer function predicts the observed ice sheet surface in most regions of the GIS with ˜90% accuracy, regardless of the presence or absence of supraglacial drainage networks. This supports the hypothesis that bedrock is the most significant driver of ice surface topography on wavelengths similar to ice thickness. Ice surface topographic asymmetry on the GIS is common, with slopes in the direction of ice flow steeper than those faced opposite to ice flow, consistent with bedrock transfer theory. At smaller wavelengths, topography consistent with fluvial erosion by surface hydrologic features is evident. We quantify the effect of ice advection versus fluvial thermal erosion on supraglacial longitudinal stream

Spatial and temporal modelling of fluvial aggradation in the Hasli Valley (Swiss Alps) during the last 1300 years

Science.gov (United States)

Llorca, Jaime; Schulte, Lothar; Carvalho, Filipe

2016-04-01

The Haslital delta (upper Aare River catchment, Bernese Alps) progradated into the Lake Brienz after the retreat of the Aare Glacier (post-LGM). Present delta plain geomorphology and spatial distribution of sedimentary facies result from historical fluvial dynamics and aggradation. Over centuries, local communities have struggled to control the Aare floods and to mitigate their effects on the floodplain (by means of raising artificial levees, channelizing the course, creating an underground drainage network, constructing dams at the basin headwaters). This study focuses on the spatial and temporal evolution of sediment dynamics of the floodplain by analyzing fluvial sedimentary records . The internal variability of lithostratigraphic sequences is a key issue to understand hydrological processes in the basin under the effect of environmental and anthropogenic changes of the past. The floodplain lithostratigraphy was reconstructed by coring alongside four cross-sections; each one is composed of more than 25 shallow boreholes (2 m deep) and two long drillings (variable depth, up to 9 m). The chronostratigraphical models were obtained by AMS 14C dating, and information of paleofloods and channel migration were reconstructed from historical sources (Schulte et al., 2015). The identification of different sedimentary facies, associated with the fluvial architecture structures, provides information on variations of vertical and lateral accretion processes (Houben, 2007). The location and geometry of buried channel-levee facies (gravel and coarse sand layers) indicate a significant mobility of the riverbed of the Hasli-Aare river, following an oscillatory pattern during the last millennia. Furthermore, fine sedimentary deposits and peat layers represent the existence of stable areas where floods have a low incidence. Once the different types of deposits were identified, aggradation rates were estimated in order to determine the spatial variability of the accumulation

SOBREVIVENCIA Y CRECIMIENTO DE PLÁNTULAS DE TRES ESPECIES ARBÓREAS EN ÁREAS DE BOSQUE MONTANO ANDINO DEGRADADAS POR GANADERÍA EN COLOMBIA

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Deisy Johanna Moreno-Betancur

2015-05-01

Full Text Available En la Región Lechera del centro de Antioquia el paisaje ha sido ampliamente transformado de bosques montanos a pastizales para pastoreo de ganado vacuno, siendo la restauración del paisaje en esta zona una acción primordial que debe ser incorporada en el plan de uso de la tierra. El objetivo general de este estudio fue seleccionar tres especies arbóreas que promuevan el proceso de regeneración de bosques montanos y evaluar el efecto de diferentes estrategias de siembra sobre el establecimiento de las plántulas. Se consideró el efecto del tipo de fertilización, combinación de especies, disponibilidad lumínica y niveles de precipitación sobre la sobrevivencia y crecimiento de las plántulas. Quercus humboldtii, Weinmannia pubescens y Myrsine coriacea fueron las especies seleccionadas por presentar alto índice de valor de importancia ecológica y alta disponibilidad de semillas. La fertilización orgánica favoreció la sobrevivencia de las tres especies evaluadas y el crecimiento para W. pubescens. La combinación de especies no afectó la tasa de crecimiento pero si la sobrevivencia. Se detectó también mayor sobrevivencia en las plántulas de las tres especies que recibieron sombra en algún momento del día; al contrario, disminuyó en la época de sequía. El éxito en el establecimiento de Q. humboldtii, la tolerancia de W. pubescens a las heladas y la dispersión de semillas de M. coriacea por aves son características que en conjunto convierten a estas especies en promisoras para procesos de restauración ecológica en áreas de bosque montano. ABSTRACT Mountain forest landscapes of the central region of Antioquia department (Colombia have been largely transformed into pastures; therefore, ecological restoration must be included as a primordial strategy. The aim of this study was the selection of three tree species that help to improve natural regeneration of mountain forest and to evaluate the effect of different sowing

Comunidad de escarabajos copronecrófagos (Coleoptera: Scarabaeidae en dos bosques del Chaco Oriental Húmedo, Argentina Copro-necrophagous beetle community (Coleoptera: Scarabaeidae in two forests from Eastern Humid Chaco, Argentina

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Miryam P. Damborsky

2008-06-01

Full Text Available Se investigó y comparó la estructura de la comunidad de Scarabaeinae en dos ambientes con distinto grado de conservación. Se efectuaron muestreos en un bosque nativo del Parque Provincial Pampa del Indio y en un fragmento de bosque del establecimiento ganadero Los Alisos. Los ejemplares se capturaron con coprotrampas y necrotrampas que permanecieron activas durante 72 horas, en los meses de octubre, noviembre y diciembre de 2006. Se colectaron 769 individuos adultos pertenecientes a seis tribus, 11 géneros y 26 especies. En Los Alisos Ontherus sulcatus Fabricius y Onthophagus hirculus Mannerheim resultaron dominantes. Trichillum sp., Canthon podagricus Harold, Malagoniella sp., Gromphas lacordairei Brullé, y dos especies de Dichotomius Hope fueron exclusivas de este establecimiento. Canthon septemmaculatus Latreille y Coprophanaeus jasius Olivier sólo se colectaron en Pampa del Indio. El número de individuos y la diversidad alcanzaron valores significativamente superiores en Pampa del Indio. En Los Alisos, se constató igual proporción de coprófagos y necrófagos, y una mayoría de especies con hábitos endocópridos y paracópridos. En Pampa del Indio, se encontraron más especies de hábitos necrófagos y rodadores. La presente contribución constituye el primer estudio sobre la biodiversidad de Scarabaeinae en el ambiente de bosque de la provincia del Chaco.Scarabaeinae community structure was compared in two habitats with different degrees of conservation: a native forest at Pampa del Indio Provincial Park, and a forest fragment at Los Alisos cattle farm. Pitfall traps baited with carrion and cattle dung were left open for 72-hour periods in October, November and December 2006. 769 adults belonging to six tribes, 11 genera and 26 species were captured in all. At Los Alisos, Ontherus sulcatus Fabricius and Onthophagus hirculus Mannerheim were the dominant species. Trichillum sp., Canthon podagricus Harold, Malagoniella sp., Gromphas

Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity.

Science.gov (United States)

Darby, Stephen E; Hackney, Christopher R; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R; Best, James L; Nicholas, Andrew P; Aalto, Rolf

2016-11-10

The world's rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being 'drowned' by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world's great deltas. We demonstrate that spatial variations in the Mekong's suspended sediment load are correlated (r = 0.765, P sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world's major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

El ecoturismo como alternativa sostenible para proteger el bosque seco tropical peruano: El caso de Proyecto Hualtaco, Tumbes

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Pedro Gonzáles Mantilla

2015-01-01

Full Text Available El bosque seco tropical peruano es un ecosistema de alto valor endémico, de riqueza biológico - - cultural y belleza paisajística, que viene siendo amenazado por los conflictos sociales y el manejo irresponsable de sus recursos. Proyecto Hualtaco es una concesión de conservación dentro de este entorno, distinguida por su localización estratégica e importancia científica. Allí se realizó una evaluación del potencial ecoturístico cuyos resultados fueron utilizados para la construcción de una propuesta de desarrollo ecoturístico que permita reconciliar la conservación del patrimonio natural y el desarrollo económico local. Se esbozaron cuatro zonas de uso dentro de la concesión. Se plantearon cinco estrategias para el desarrollo ecoturístico, a través de 33 actividades, programadas en un plazo de dos años. Finalmente, se delinearon diez mecanismos para la generación de ingresos y 28 indicadores de manejo y monitoreo del ecoturismo, elementos claves para el éxito de la propuesta.

Investigating the use of the dual-polarized and large incident angle of SAR data for mapping the fluvial and aeolian deposits

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Ahmed Gaber

2017-12-01

Full Text Available Mapping the spatial distributions of the fluvial deposits in terms of particles size as well as imaging the near-surface features along the non-vegetated aeolian sand-sheets, provides valuable geological information. Thus this work aims at investigating the contribution of the dual-polarization SAR data in classifying and mapping the surface sediments as well as investigating the effect of the radar incident-angle on improving the images of the hidden features under the desert sand cover. For mapping the fluvial deposits, the covariance matrix ([C2] using four dual-polarized ALOS/PALSAR-1 scenes cover the Wadi El Matulla, East Qena, Egypt were generated. This [C2] matrix was used to generate a supervised classification map with three main classes (gravel, gravel/sand and sand. The polarimetric scattering response, spectral reflectance and temperatures brightness of these 3 classes were extracted. However for the aeolian deposits investigation, two Radarsat-1 and three full-polarimetric ALOS/PALSAR-1 images, which cover the northwestern sandy part of Sinai, Egypt were calibrated, filtered, geocoded and ingested in a GIS database to image the near-surface features. The fluvial mapping results show that the values of the radar backscattered coefficient (σ° and the degree of randomness of the obtained three classes are increasing respectively by increasing their grain size. Moreover, the large incident angle (θi = 39.7 of the Radarsat-1 image has revealed a meandering buried stream under the sand sheet of the northwestern part of Sinai. Such buried stream does not appear in the other optical, SRTM and SAR dataset. The main reason is the enhanced contrast between the low backscattered return from the revealed meandering stream and the surroundings as a result of the increased backscattering intensity, which is related to the relatively large incident angle along the undulated surface of the study area. All archaeological

Zeroing of the TL signal of sediment undergoing fluvial transportation: a laboratory experiment

International Nuclear Information System (INIS)

Gemmell, A.M.D.

1985-01-01

Rates of bleaching of suspended sediment undergoing fluvial transportation in a closed laboratory flume beneath a u.v. lamp were measured. It was found that the speed of zeroing is inversely related to the speed of flow. This is attributed to the effects of flow turbulence in keeping sediment in suspension, thereby reducing the penetration of u.v. radiation, and to the re-entrainment of partially bleached or unbleached sediment into the flow. The time required to reduce TL to the residual levels indicated by sunlamp bleaching experiments are such as to suggest that at faster flows sediments in a heavily-laden stream may never attain a complete bleaching. (author)

Evolution of Subaerial Coastal Fluvial Delta Island Topography into Multiple Stable States Under Influence of Vegetation and Stochastic Hydrology

Science.gov (United States)

Moffett, K. B.; Smith, B. C.; O'Connor, M.; Mohrig, D. C.

2014-12-01

Coastal fluvial delta morphodynamics are prominently controlled by external fluvial sediment and water supplies; however, internal sediment-water-vegetation feedbacks are now being proposed as potentially equally significant in organizing and maintaining the progradation and aggradation of such systems. The time scales of fluvial and climate influences on these feedbacks, and of their responses, are also open questions. Historical remote sensing study of the Wax Lake Delta model system (Louisiana, USA) revealed trends in the evolution of the subaerial island surfaces from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. We propose that this elevation zonation is consistent with multiple stable state theory, e.g. as applied to tidal salt marsh systems but not previously to deltas. According to zonally-distributed sediment core analyses, differentiation of island elevations was not due to organic matter accumulation as in salt marshes, but rather by differential mineral sediment accumulation with some organic contributions. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, at least to date in this young delta, in contrast to theory suggesting rates should slow as elevation increases above mean water level. Hydrological analysis of island flooding suggested a prominent role of stochastic local storm events in raising island water levels and supplying mineral sediment to the subaerial island surfaces at short time scales; over longer time scales, the relative influences of local storms and inland/regional floods on the coupled sediment-water-vegetation system of the subaerial delta island surfaces remain the subject of ongoing study. These results help provide an empirical foundation for the next generation of coupled sediment-water-vegetation modeling and theory.

Distinguishing regional and local sources of pollution by trace metals and magnetic particles in fluvial sediments of the Morava River, Czech Republic

Czech Academy of Sciences Publication Activity Database

Nováková, Tereza; Matys Grygar, Tomáš; Bábek, O.; Famera, M.; Mihaljevič, M.; Strnad, L.

2013-01-01

Roč. 13, č. 2 (2013), s. 460-473 ISSN 1439-0108 Institutional support: RVO:61388980 Keywords : Enrichment factors * Fluvial sediments * Heavy metals * Local sources * Normalisation * Regional contamination Subject RIV: DD - Geochemistry Impact factor: 2.107, year: 2013

Fluvial Export Variability Of Limiting Nutrient Fluxes To The Indian Ocean From Kelani, Kalu and Gin Rivers Of Sri Lanka

Science.gov (United States)

Ranasinghage, P. N.; Silva, A. N.; Vlahos, P.

2016-12-01

Inorganic `reactive' nutrients hold the highest importance in understanding the role of limiting nutrients in the ocean since they facilitate marine biological productivity and carbon sequestration that would eventually pave the way to regulate the biogeochemical climate feedbacks. Significant inorganic fractions are expected to be exported episodically to the ocean from fluvial fluxes though this is poorly understood. Thus, no considerable amounts of published work regarding the fluxes from Sri Lankan freshwater streams have ever been recorded. A study was carried out to quantify the contribution of Kelani, Kalu and Gin Rivers, three major rivers in the wet zone of Sri Lanka, in exporting major limiting nutrient fluxes to the Indian Ocean; to understand the significance of their variability patterns with rainfall and understand differences in their inputs. The study was conducted during the summer monsoonal period from late August to early November at two-three week intervals where water samples were collected for ammonia, nitrite, nitrate, orthophosphate, silica, sulfate and iron analysis by Colorimetric Spectroscopy. Discharge and rainfall data were retrieved from the Department of Irrigation and Department of Meteorology, Sri Lanka respectively. According to Two Way ANOVA, none of the individual fluxes showed significant differences (p>0.1) both in their temporal and spatial variability suggesting that studied rivers respond similarly in fluvial transportation owing to the similar rainfall intensities observed during the study period in the wet zone. Linear Regression Analysis indicates that only PO43- (p<0.01), SO42- (p<0.01) and NO2-(p<0.01 for Kelani and Kalu; 0.0.1Key words; nutrients, fluvial, fluxes, Redfield ratios

Trends in publications in fluvial geomorphology over two decades: A truly new era in the discipline owing to recent technological revolution?

Science.gov (United States)

Piégay, Hervé; Kondolf, G. Mathias; Minear, J. Toby; Vaudor, Lise

2015-01-01

Trends in the field of fluvial geomorphology have been reviewed by a number of authors, who have emphasized the dramatic change occuring in the field in the last two decades of the twentieth century, largely as a result of technological advances. Nevertheless, no prior authors have systematically compiled data on publications in fluvial geomorphology over a long period and statistically analyzed the resulting data set. In this contribution we present a quantitative analysis of fluvial geomorphology papers published in the twenty-two-year period 1987–2009 in five journals of the discipline with a more specific focus on Geomorphology and Earth Surface Processes and Landforms (ESPL), identifying authorships, geographic origin of authors, and spatial and temporal scales covered. We also documented the tools employed, demonstrating the transformation of the field with the emergence of new tools over this period, and conducted a cluster to highlight links between tools and a set of factors (country of author's origin, journals, time, and spatial and temporal scales). Of the 1717 papers published in the five journals during this period, the results showed an increased diversity in the nationality of the first author, mainly when dealing with present time scale, and channel feature. Our data show a significant change in methods used in the field as a result of the increase in data availability and new sources of information from remote sensing (ground, airborne and, satellite). Clearly, a new era in knowledge production is observed since 2000, showing the emergence of a second period of active quantification and an internationalization of the fields.

Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in frio fluvial-deltaic sandstone reservoirs at South Texas. Annual report, October 1994--October 1995

Energy Technology Data Exchange (ETDEWEB)

Holtz, M.; Knox, P.; McRae, L. [and others

1996-02-01

The Frio Fluvial-Deltaic Sandstone oil play of South Texas has produced nearly 1 billion barrels of oil, yet it still contains about 1.6 billion barrels of unrecovered mobile oil and nearly the same amount of residual oil resources. Interwell-scale geologic facise models of Frio Fluvial-deltaic reservoirs are being combined with engineering assessments and geophysical evaluations in order to determine the controls that these characteristics exert on the location and volume or unrecovered mobile and residual oil. Progress in the third year centered on technology transfer. An overview of project tasks is presented.

Contrasting vulnerability of drained tropical and high-latitude peatlands to fluvial loss of stored carbon

Science.gov (United States)

Evans, Chris D.; Page, Susan E.; Jones, Tim; Moore, Sam; Gauci, Vincent; Laiho, Raija; Hruška, Jakub; Allott, Tim E. H.; Billett, Michael F.; Tipping, Ed; Freeman, Chris; Garnett, Mark H.

2014-11-01

Carbon sequestration and storage in peatlands rely on consistently high water tables. Anthropogenic pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of peat-forming vegetation and exposure of previously anaerobic peat to aerobic decomposition. This can shift peatlands from net CO2 sinks to large CO2 sources, releasing carbon held for millennia. Peatlands also export significant quantities of carbon via fluvial pathways, mainly as dissolved organic carbon (DOC). We analyzed radiocarbon (14C) levels of DOC in drainage water from multiple peatlands in Europe and Southeast Asia, to infer differences in the age of carbon lost from intact and drained systems. In most cases, drainage led to increased release of older carbon from the peat profile but with marked differences related to peat type. Very low DOC-14C levels in runoff from drained tropical peatlands indicate loss of very old (centuries to millennia) stored peat carbon. High-latitude peatlands appear more resilient to drainage; 14C measurements from UK blanket bogs suggest that exported DOC remains young (use changes in the tropics. Data from the UK Peak District, an area where air pollution and intensive land management have triggered Sphagnum loss and peat erosion, suggest that additional anthropogenic pressures may trigger fluvial loss of much older (>500 year) carbon in high-latitude systems. Rewetting at least partially offsets drainage effects on DOC age.

Desarrollo sustentable y manejo de bosques naturales en la Amazonía peruana : un estudio económico ambiental del sistema de manejo forestal en fajas en el valle del Palcazu

OpenAIRE

Elgegren Apuela, Jorge Octavio

1993-01-01

Es obvio que los bosques tropicales tienen valores pertenecientes a la esfera del mercado y valores que escapan a su influencia: por ejemplo, la madera es un producto que tiene (casi siempre) valor de mercado; en cambio, la protección del cauce de un río por parte de la cubierta vegetal no tiene un valor de mercado. Esta asimetría en la asignación de valores implica un sesgo considerable a favor del uso de la tierra hacia fines lucrativos más que de conservación y es una causa fundamental par...

Multi-residues analysis of pre-emergence herbicides in fluvial sediments: application to the mid-Garonne River.

Science.gov (United States)

Devault, Damien A; Merlina, Georges; Lim, Puy; Probst, Jean-Luc; Pinelli, Eric

2007-09-01

Contamination of man and ecosystems by pesticides has become a major environmental concern. Whereas many studies exist on contamination from agriculture, the effects of urban sources are usually omitted. Fluvial sediment is a complex matrix of pollutants but little is known of its recent herbicide content. This study proposes a method for a fast and reliable analysis of herbicides by employing the accelerated solvent extractor (ASE). The aim of the study is to show the impact of a major town (Toulouse) on the herbicide content in the river. In this study, three herbicide families (i.e.s-triazine, substituted ureas and anilides) were analysed in fluvial sediment fractions at 11 sampling sites along the mid-Garonne River and its tributaries. River water contamination by herbicides is minor, except for at three sites located in urban areas. Among the herbicidal families studied, urban and suburban areas are distinguished from rural areas and were found to be the most contaminated sites during the study period, a winter low-water event. The herbicide content of the coarse sediment fractions is about one third of that found in the fine fractions and usually ignored. The distribution of pesticide concentrations across the whole range of particle sizes was investigated to clarify the role of plant remains on the significant accumulation in the coarse fractions.

Composición florística y estructura de un bosque húmedo premontano en el Valle Central de Costa Rica

Directory of Open Access Journals (Sweden)

Alfredo Cascante M.

2001-03-01

Full Text Available Se estudió la estructura y composición florística de un remanente de bosque húmedo premontano (BHP en la Zona Protectora El Rodeo, Valle Central de Costa Rica. Se establecieron tres parcelas permanentes (1 ha. cada una en el bosque no alterado y se marcaron, midieron e identificaron todos los árboles con un diámetro a la altura del pecho (dap >10 cm. Las parcelas se ubicaron en un área de 500 m de radio. Se encontró un total de 106 especies, con un promedio de 69.6 especies ha-1 y 509 individuos ha-1, el área basal promedio 36.35 m² ha-1. La diversidad fue H’= 3.54 (Índice de Shannon y las especies compartidas entre las parcelas S=0.68-0.70 (Índice de Similitud de Sørensen. El 52% de las especies estuvieron representadas por pocos individuos (cinco o menos. No se encontró árboles emergentes o palmas arborescentes. La familia Moraceae es la más importante, seguida de Fabaceae, Lauraceae y Sapotaceae (Índice de Importancia Familiar, FIV. Pseudolmedia oxyphillaria (Moraceae es la especie dominante (Índice de Valor de Importancia, IVI y constituye el 25% del total de individuos; seguida por Clarisia racemosa (Moraceae, Heisteria concinna (Olacaceae y Brosimum alicastrum (Moraceae como especies más relevantes. La distribución por categorías diamétricas fue similar en las tres parcelas y en general presentó la característica forma de J-invertida. Diferencias en cuanto a la abundancia de árboles, composición florística y distribución espacial de algunas especies entre las parcelas de estudio evidencian la heterogeneidad de la vegetación de este ecosistema. Además, la zona constituye un reservorio natural importante para la conservación de algunas especies raras o amenazadas en el nivel nacional. Utilizando los resultados de este trabajo como punto de partida, se pretende iniciar el seguimiento a largo plazo de los posibles cambios en la estructura y composición del bosque de este ecosistema, el cual se encuentra muy

Modelamiento geoestadístico de los depósitos fluviales de la zona c-formación mugrosa en el área la Cira-Este del Campo La Cira

OpenAIRE

Rojas Suárez, César Augusto

2011-01-01

Mediante algoritmos geoestadísticos se realizo el modelo tridimensional de los yacimientos fluviales de la Zona-C de la Formación Mugrosa en el área Cira-Este del Campo La Cira. Este modelo permitió calcular el aceite original en sitio e identificar las reservas que aun no han sido drenadas en el yacimiento. / Abstract. Geostatistical algorithms were used for making the three-dimensional model for the fluvial deposits of Zona-C of Mugrosa Formation in the Cira-Este area of the Cira Field. Thi...

Changing fluvial styles in volcaniclastic successions: A cretaceous example from the Cerro Barcino Formation, Patagonia

Science.gov (United States)

Umazano, A. Martín; Krause, J. Marcelo; Bellosi, Eduardo S.; Perez, Mariano; Visconti, Graciela; Melchor, Ricardo N.

2017-08-01

The Cretaceous Puesto La Paloma (PLPM) and Cerro Castaño (CCM) members (Cerro Barcino Formation, Chubut Group) are pyroclastic-rich, alluvial successions deposited in the Somuncurá-Cañadón Asfalto Basin during sag and endorheic conditions. The PLPM comprises sheet-like tuffaceous sandstone strata, whereas the overlying CCM includes sheet-to ribbon-channel sandstone bodies intercalated within tuffaceous and fine-grained sediments. In this context, the goals of this contribution were: i) to make a detailed documentation of the contrasting sedimentary palaeonvironments; and ii) to infer the allocyclic controls that governed the sedimentation of both units. The study area is located in the western sector of the basin, where six localities, which were studied. Six facies associations were defined including ash-falls, sheet-floods, shallow lakes, aeolian, fluvial channel-belts, and reworked debris-flows. We defined four stratigraphic intervals for the studied sections, denominated 1 to 4 in chronological order of deposition, which increase their thicknesses toward the Puesto Mesa-Cerro León site. The interval 1 (18-42 m thick) corresponds to the PLPM and includes numerous pedogenized sheet-flood deposits, carbonate-rich lacustrine, aeolian sandy facies, and ash-fall beds. The interval 1 is interpreted as an ephemeral and unconfined alluvial system that interacted with aeolian dunes and dry interdune zones. The interval 2 (20-47 m thick) represents the lower part of the CCM. It shows an alternation of fluvial channel-belt deposits and vegetated floodplain facies with sediments originated from sheet-floods, lakes, and few ash-falls and debris-flows. The mean palaeoflow was toward E-SE, except in the northernmost locality where the drainage was towards SW. Proportion of channel-belt bodies ranges from 10 to 36%, reaching higher values in the northern part of the study area, where they are also thicker. The interval 2 represents a permanent, meandering or locally low

Petrology and provenance of the Neogene fluvial succession in Pishin Belt (Katawaz Basin) western Pakistan: Implications for sedimentation in peripheral forelands basins

DEFF Research Database (Denmark)

Kasi, Aimal Khan; Kassi, Aktar Muhammad; Friis, Henrik

2017-01-01

Sandstones and conglomerates of the Neogene fluvial succession in Pishin Belt (Katawaz Basin), Pakistan were studied for the first time to understand the composition, provenance and tectonic settings of the source areas. Sandstones of the Miocene Dasht Murgha Group and Pliocene Malthanai Formatio...

Insights into organic carbon oxidation potential during fluvial transport from controlled laboratory and natural field experiments

Science.gov (United States)

Scheingross, Joel S.; Dellinger, Mathieu; Golombek, Nina; Hilton, Robert G.; Hovius, Niels; Sachse, Dirk; Turowski, Jens M.; Vieth-Hillebrand, Andrea; Wittmann, Hella

2017-04-01

Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, biosphere and geosphere is thought to be a major control on atmospheric carbon dioxide (CO2) concentrations, and hence global climate. The carbon fluxes from the oxidation of rock-derived OC (a CO2 source) and erosion and transport of biospheric OC (a potential CO2 sink) during fluvial transit are approximately the same order of magnitude or larger than those from silicate weathering (France-Lanord and Derry, 1997; Bouchez et al., 2010). Despite field data showing oxidation of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in both controlled laboratory experiments and a simplified field setting. We consider both rock-derived and biospheric OC. Our experiments simulated fluvial transport without floodplain storage, allowing mixtures of OC-rich and siliciclastic sediment to be transported for distances of 1000 km in annular flumes while making time-series measurements of OC concentration in both the solid (POC) and dissolved (DOC) loads, as well as measurements of rhenium concentration, which serves as a proxy for the oxidation of rock-derived OC. These transport experiments were compared to static, control experiments where water and sediment in the same proportion were placed in still water. Initial results for transport of OC-rich soil show similar behavior between the transport and static

Expansión urbana, PRMS y el corredor fluvial del Rio Mapocho inferior /Urban growth, planning instruments and the lower Mapocho River basin

Directory of Open Access Journals (Sweden)

Francisco Ferrando Acuña

2010-06-01

Full Text Available Se analiza la relevancia de los servicios ambientales de los corredores fluviales en el ámbito de la planificación urbana sustentable, al tenor de la realidad y falencias de los instrumentos territoriales vigentes en esta temática. Dados los múltiples servicios ambientales de esto tipo de sistema natural, escasamente valorizado y nada incorporado en los IOT en Chile, al contrario de experiencias extranjeras como las españolas, se rescata y explicitan las características del corredor inferior del Río Mapocho entre la Comuna de Maipú y el Monte desde el punto de vista geomorfológico, hidrológico y ambiental, y se señala la relevancia de su temprana incorporación en los proyectos de urbanización de este territorio, los cuales ya se encuentran en marcha a propósito del progresivo cambio de uso del suelo de rural a urbano. /In Chile there's no correlation between the environmental relevance of the fluvial corridors and its many benefic functions for the urban climate and quality of life of his inhabitants with planning instruments. Consequently these fluvial systems aren't the basis of city planning setting aside its environmental services not only for cities, also for regions and more. The lower Río Mapocho corridor is evaluated considering the land use change in its surroundings. A review is presentes of international experiences on this matter, particularly from Spain.

The impact of urban expansion and agricultural legacies on trace metal accumulation in fluvial and lacustrine sediments of the lower Chesapeake Bay basin, USA

International Nuclear Information System (INIS)

Coxon, T.M.; Odhiambo, B.K.; Giancarlo, L.C.

2016-01-01

The progressively declining ecological condition of the Chesapeake Bay is attributed to the influx of contaminants associated with sediment loads supplied by its largest tributaries. The continued urban expansion in the suburbs of Virginia cities, modern agricultural activities in the Shenandoah Valley, the anthropogenic and climate driven changes in fluvial system hydrodynamics and their potential associated impacts on trace metals enrichment in the bay's tributaries necessitate constant environmental monitoring of these important water bodies. Eight "2"1"0Pb and "1"3"7Cs dated sediment cores and seventy two sediment grab samples were used to analyze the spatial and temporal distributions of Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, and Fe in the waterways of the Virginia portion of the Chesapeake Bay basin. The sediment cores for trace metal historical fluctuation analysis were obtained in lower fluvial-estuarine environments and reservoirs in the upper reaches of the basin. The trace metal profiles revealed high basal enrichment factors (EF) of between 0.05 and 40.24, which are interpreted to represent early nineteenth century agricultural activity and primary resource extraction. Surficial enrichment factors on both cores and surface grab samples ranged from 0.01 (Cu) to 1421 (Cd), with Pb, Cu, Zn, and Cd enrichments a plausible consequence of modern urban expansion and industrial development along major transportation corridors. Contemporary surficial enrichments of As, Se, and Cr also ranged between 0 and 137, with the higher values likely influenced by lithological and atmospheric sources. Pearson correlation analyses suggest mining and agricultural legacies, coupled with aerosol deposition, are responsible for high metal concentrations in western lakes and headwater reaches of fluvial systems, while metal accumulation in estuarine reaches of the major rivers can be attributed to urban effluence and the remobilization of legacy sediments. - Highlights: �

The impact of urban expansion and agricultural legacies on trace metal accumulation in fluvial and lacustrine sediments of the lower Chesapeake Bay basin, USA

Energy Technology Data Exchange (ETDEWEB)

Coxon, T.M. [Department of Earth and Environmental Sciences, University of Mary Washington, 1301 College Avenue Fredericksburg, Virginia 22401 (United States); Odhiambo, B.K., E-mail: bkisila@umw.edu [Department of Earth and Environmental Sciences, University of Mary Washington, 1301 College Avenue Fredericksburg, Virginia 22401 (United States); Giancarlo, L.C. [Department of Chemistry, University of Mary Washington, Fredericksburg, VA 22401 (United States)

2016-10-15

The progressively declining ecological condition of the Chesapeake Bay is attributed to the influx of contaminants associated with sediment loads supplied by its largest tributaries. The continued urban expansion in the suburbs of Virginia cities, modern agricultural activities in the Shenandoah Valley, the anthropogenic and climate driven changes in fluvial system hydrodynamics and their potential associated impacts on trace metals enrichment in the bay's tributaries necessitate constant environmental monitoring of these important water bodies. Eight {sup 210}Pb and {sup 137}Cs dated sediment cores and seventy two sediment grab samples were used to analyze the spatial and temporal distributions of Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, and Fe in the waterways of the Virginia portion of the Chesapeake Bay basin. The sediment cores for trace metal historical fluctuation analysis were obtained in lower fluvial-estuarine environments and reservoirs in the upper reaches of the basin. The trace metal profiles revealed high basal enrichment factors (EF) of between 0.05 and 40.24, which are interpreted to represent early nineteenth century agricultural activity and primary resource extraction. Surficial enrichment factors on both cores and surface grab samples ranged from 0.01 (Cu) to 1421 (Cd), with Pb, Cu, Zn, and Cd enrichments a plausible consequence of modern urban expansion and industrial development along major transportation corridors. Contemporary surficial enrichments of As, Se, and Cr also ranged between 0 and 137, with the higher values likely influenced by lithological and atmospheric sources. Pearson correlation analyses suggest mining and agricultural legacies, coupled with aerosol deposition, are responsible for high metal concentrations in western lakes and headwater reaches of fluvial systems, while metal accumulation in estuarine reaches of the major rivers can be attributed to urban effluence and the remobilization of legacy sediments

Gramática descriptiva de la lengua española dirigida por Ignacio Bosque y Violeta Demonte publicada por Real Academia española, collección Nebrija y Bello. Madrid: Espasa Calpe, 1999

Directory of Open Access Journals (Sweden)

Jasmina Markič

2001-12-01

Full Text Available La Gramatica Descriptiva de la Lengua Española es una obra muy extensa de 5351 paginas mas las paginas de introducción, relación de autores e índice de contenidos, publicada en tres volúmenes y dirigida por dos eminentes lingüistas españoles Ignacio Bosque Mufioz, Catedratico de Lengua Espafiola en la Universidad Complutense de Madrid y miembro de la Real Academia Espafiola, y Violeta Demonte Barreto, Catedratica de Lengua Espafiola en la Universidad Autónoma de Madrid.

TRAMPEO DE Phytophthora cinnamomi EN BOSQUE DE ENCINO CON DOS ESPECIES ORNAMENTALES E INDUCCIÓN DE SU ESPORULACIÓN

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Alejandra Almaraz-Sánchez

2013-01-01

Full Text Available La mortalidad del encino se ha acentuado recientemente en varios estados del país. La etiología en muchos casos se desconoce. Los bosques de encino están siendo afectados por la “enfermedad de la tinta” (Phytophthora cinnamomi Rands. en los estados de Colima, Jalisco y Guerrero. La enfermedad causada por P. cinnamomi es de gran importancia; sin embargo, el aislamiento y la esporulación del patógeno representan una gran dificultad. Debido a lo anterior, los objetivos del presente estudio fueron a evaluar la eficiencia de dos plantas trampa, Camellia japonica y Rhododendron indicum (L. Sweet utilizando una suspensión de suelo y b inducir la esporulación del patógeno. Para ello, discos de tejido foliar (6 mm de las especies trampa fueron embebidos en una suspensión de suelo por 24 y 48 h para luego ser sembrados en medio selectivo PARPH. La especie R. indicum presentó una mayor efectividad de captura de 64.10 % comparada con 6.83 % de C. japonica. Los mejores resultados de esporulación se obtuvieron con una mezcla de agua-suelo (350 mL-200 g.

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal - Appendix)

Energy Technology Data Exchange (ETDEWEB)

Bou-Mikael, Sami

2002-02-05

The main objective of the Port Neches Project was to determine the feasibility and producibility of CO2 miscible flooding techniques enhanced with horizontal drilling applied to a Fluvial Dominated Deltaic reservoir. The second was to disseminate the knowledge gained through established Technology Transfer mechanisms to support DOE's programmatic objectives of increasing domestic oil production and reducing abandonment of oil fields.

Glacial lake outburst floods and fluvial erosion in the Himalaya - insights from the 2016 Bhote Koshi GLOF

Science.gov (United States)

Cook, K. L.; Gimbert, F.; Andermann, C.; Hovius, N.; Adhikari, B. R.

2017-12-01

The Himalaya is a region of rapid erosion where fluvial processes are assumed to be driven by precipitation delivered during the annual Indian Summer Monsoon. However, the rivers in this region are also subject to catastrophic floods caused by the failure of glacial lake and landslide dams. Because these floods are rarely observed, it has been difficult to isolate their impact on the rivers and adjacent hillslopes, and their importance for the long-term evolution of Himalayan valleys is largely unknown. In July 2016, the Bhotekoshi/Sunkoshi River in central Nepal was hit by a glacial lake outburst flood (GLOF) that caused substantial changes to the channel bed, banks, and adjacent hillslopes, causing at least 26 landslides and an average of 11 m of channel widening. The flood passed through a seismic and hydrological observatory installed along the river in June 2015, and we have used the resulting data to constrain the timing, duration, and bedload transport properties of the outburst flood. The impact of the flood on the river can be further observed with hourly time-lapse photographs, daily measurements of suspended sediment load, repeat lidar surveys, and satellite imagery. The outburst flood affected the river on several timescales. In the short term, it transported large amounts of coarse sediment and restructured the river bed during the hours of the flood pulse itself. Over intermediate timescales it resulted in elevated bedload and suspended load transport for several weeks following the flood. Over longer timescales the flood undercut and destabilized the river banks and hillslopes in a number of locations, leading to bank collapses, slumps, and landslides. Our data indicate that impacts of the GLOF far exceed those driven by the annual summer monsoon, likely due to extremely coarse sediment that armors much of the channel. The relatively frequent occurrence of GLOFs and the extremely high discharges relative to monsoon floods suggest that GLOFs may

Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

Science.gov (United States)

Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

2014-05-01

Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal), Class I

Energy Technology Data Exchange (ETDEWEB)

Bou-Mikael, Sami

2002-02-05

This project outlines a proposal to improve the recovery of light oil from waterflooded fluvial dominated deltaic (FDD) reservoir through a miscible carbon dioxide (CO2) flood. The site is the Port Neches Field in Orange County, Texas. The field is well explored and well exploited. The project area is 270 acres within the Port Neches Field.

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

Science.gov (United States)

Mahan, S.A.; Brown, D.J.

2007-01-01

There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

Late quaternary evolution of the Meuse fluvial system and its sediment composition : a reconstruction based on bulk sample geochemistry and forward modelling

NARCIS (Netherlands)

Tebbens, L.A.

1999-01-01

All fluvial systems ultimately drain into alluvial basins, where the weathering products of their upstream drainage areas accumulate over a time-span varying from 10 ⁰to 10 ⁶years. Most silted-up alluvial basins are low-gradient deltas that are

Valley-scale morphology drives differences in fluvial sediment budgets and incision rates during contrasting flow regimes

Science.gov (United States)

Weber, M. D.; Pasternack, G. B.

2017-07-01

High-resolution topographic surveys using LiDAR and multibeam sonar can be used to characterize and quantify fluvial change. This study used repeat surveys to explore how topographic change, fluvial processes, sediment budgets, and aggradation and incision rates vary across spatial scales and across two contrasting decadal flow regimes in a regulated gravel/cobble river. A novel method for quantifying digital elevation model uncertainty was developed and applied to a topographic change detection analysis from 2006/2008 to 2014. During this period, which had four modest 3-5 year floods, most sediment was laterally redistributed through bank erosion and channel migration. Erosion primarily occurred in the floodplain (97,000 m3), terraces (80,000 m3), and lateral bars (58,000 m3); while deposition occurred in the adjacent pools (73,000 m3), fast glides (48,000 m3), and runs (36,000 m3). In contrast, significantly higher magnitude and longer duration floods from 1999 to 2006/2008 caused sediment to be displaced longitudinally, with the upstream reaches exporting sediment and the downstream reaches aggrading. The river maintained floodplain connectivity during both periods, despite different processes dominating the type of connectivity. Larger floods promoted overbank scour and avulsion, while smaller floods promoted bank erosion and lateral migration. This study explores and illustrates how the geomorphic response to contrasting flood regimes in a nonuniform river is highly dependent on which landforms are controlling hydraulics.

Atractividad de diferentes cebos sobre Trógidos (Coleoptera en el Bosque Autóctono "El Espinal", Río Cuarto (Córdoba, Argentina

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Rodrigo S. GÓMEZ

2005-01-01

Full Text Available Se efectuó un estudio para determinar la atractividad de cebos sobre las especies de Trogidae presentes en el Bosque Autóctono "El Espinal" en la ciudad de Río Cuarto (Córdoba, Argentina. Se usaron trampas de caída cebadas con carne de vacuno (3, carne de porcino (3, menudo de pollo (3, excremento humano (3, excremento de perro (3 y trampas testigo (sin cebo (3 sumando un total de 18. Se recolectaron cuatro especies de Trogidae: Omorgus suberosus (Fabricius, Polynoncus aeger (Guérin – Meneville, Polynoncus gemmingeri (Harold y Polynoncus pilularius (Germar, que mostraron una preferencia hacia los menudos en descomposición de pollo y carne de cerdo seguido por excremento de perro; sugiriendo un comportamiento necrofágico – coprofágico con una tendencia a la necrofagia. Adicionalmente se utilizaron trampas de luz capturándose ejemplares de Omorgus ciliatus (Blanchard

Recuperación del paisaje con fines de ocio. Parque fluvial del Jarama. Comunidad de Madrid. España

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Pinedo, Alejandro

1990-10-01

Full Text Available This paper focuses on a rivershore reclamation scheme for an area of the Community of Madrid (Spain. Due to its location not far from the City of Madrid, recreational water based use was proposed as the final use for this disturbed river environment. The reclamation plan proposes the creation of the Jarama River Park (Parque Fluvial del Jarama that would be integrated into the Rivershore Reclamation Program of the Integral Water Plan of Madrid (Plan Integral del Agua en Madrid-PIAM. Several sets of actions are considered for the reclamation of the river and ponds system. Some of them are: — Reclamation of the old railway corridor located along the river. — Reclamation of the river bed and banks. — Reclamation of the Campillo Pond area.

El plan de recuperación de márgenes y riberas que se describe en el presente artículo, trata de salir al paso y aportar soluciones a los cada vez más frecuentes problemas de restauración y aprovechamiento de terrenos degradados que se plantean en los ámbitos urbanos y periurbano. El plan se localiza geográficamente en un área de la Comunidad de Madrid que posee un alto nivel de degradación y al mismo tiempo un gran potencial recreativo, se trata de el Parque Fluvial del Jarama, situado en el tramo del río Jarama comprendido entre la desembocadura del arroyo de la Vega y la del Manzanares; el Parque Fluvial del Jarama constituye la actuación más ambiciosa dentro del Programa de Recuperación de Márgenes del Plan Integral del Agua en Madrid (PIAM y en él se contemplan una serie de actuaciones que se pueden agrupar en los bloques siguientes: — Restauración de la explanación del ferrocarril. — Restauración y adecuación del cauce y márgenes. — Restauración de la Laguna del Campillo.

Efecto del corredor vial Buga-Buenaventura, ubicado en la reserva natural bosque de Yotoco (Valle del Cauca, Colombia en la comunidad de mamíferos y fundamento para una propuesta de corredores artificiales

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Wendy Francy López Meneses

2006-07-01

de movilidad de la fauna, por la carretera Buga-Buenaventura que pasa a través de la Reserva Natural Bosque de Yotoco, Valle del Cauca. La caracterización topográfica y fisionómica de la vegetación mostró un mosaico de diez ambientes asociados a la carretera los cuales se asociaron con los puntos captura, de observación y de atropellamiento. Se encontró que individuos de Melanomys caliginosus, Oryzomys talamancae, Rhipidomys mastacalis y Marmosa robinsoni, recapturados en más de tres ocasiones, tienden a moverse paralelamente a la carretera, sin ninguna evidencia de cruce. A pesar de que no hubo recapturas de individuos de las especies de mamíferos voladores Anoura cauddifer, Artibeus jamaicensis, Artibeus sp., Carollia brevicauda, Desmodus rotundus, Glosophaga Soricina, Sturnira luisi y Myotis riparius se puede afirmar que cruzan indiferentemente la carretera, viven en los desagues bajo esta y algunos forrajean en el borde. Particularmente Myotis riparius se ve atraída por los insectos que llegan por efecto de la luz vehicular. Los mamíferos medianos y grandes Cebus capucinus, Alouatta seniculus, Potos flavus, Aotus sp., Bradypus variegatus y Choloepus hoffmanni, forrajean en el día y en la noche cerca del borde, algunos individuos de Cebus capucinus y Alouatta seniculus fueron vistos cruzando la carretera del fragmento pequeño al grande. La fragmentación de hábitat ocasionada por dicha carretera es evidente y está ocasionando un aislamiento total en las especies de pequeños mamíferos y genera peligro de atropellamiento para algunas especies de murciélagos y monos que la cruzan. Ambientes hostiles como helechales, pastizales, cañaduzales y deslizamientos penetran cada vez más hacia el interior de cada fragmento, aislando las poblaciones y abriendo paso a fauna doméstica y a personas que se adentran a la reserva a cazar o a saquear recursos de supervivencia para la fauna nativa, al tiempo que introducen desechos, plagas (Rattus rattus

Regeneración de un bosque mixto de Nothofagus (Nothofagaceae después de una corta selectiva Regeneration of a Nothofagus (Nothofagaceae mixed forest after selective cutting

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ALEJANDRO DEZZOTTI

2003-12-01

Full Text Available El estudio de la ecología de la regeneración natural del bosque constituye una parte esencial de la silvicultura. El cerro Tren Tren (40°12' S, 71°26' O, 1.367 m, Reserva Mapuche Curruhuinca, Argentina está ocupado por un bosque cerrado compuesto por Nothofagus dombeyi, N. nervosa y N. obliqua. En 1994 se estimó la densidad de renovales (diámetro en la base del tallo Understanding forest regeneration is essential to develop sound, ecologically-based silvicultural practices. Mount Tren Tren (40°12' S, 71°26' W, 1,367 m, Reservation Mapuche Curruhuinca, Argentina is occupied by a closed stand of Nothofagus dombeyi, N. obliqua, and N. nervosa. In 1994, tree regeneration (root collar diameter < 10 cm was estimated to be 90 ind ha-1. After that, a group selection silvicultural system was implemented and the resulting 10 artificial gaps of between 1,587 and 4,322 m² were enclosed to prevent grazing by domestic livestock. Size and age structure of regeneration were analysed based on systematic and random samplings. All tree species became established simultaneously within the artificial gaps. However, the less light demanding N. nervosa exhibited a mean age slightly larger given its differential persistence as "advanced regeneration" previous to cutting treatment. Tree regeneration was estimated in 97,006 ind ha-1 (68 % of N. dombeyi, 20 % of N. obliqua, and 12 % of N. nervosa. Regeneration abundance and composition were unrelated to shape and size of regeneration gaps, nor to abundance of adult trees within the stand and along the gap boundaries. A significant positive effect of the enclosure on plant was observed. The 86 % of juvenile Nothofagus were present when understory height and cover were low to intermediate. The management plan is considered adequate if the abundance of regeneration is compared before and after its implementation, and encourages the use and conservation of this forest type under the current silvicultural system

A chemometric approach to the evaluation of atmospheric and fluvial pollutant inputs in aquatic systems: The Guadalquivir River estuary as a case study

International Nuclear Information System (INIS)

Lopez-Lopez, Jose A.; Garcia-Vargas, Manuel; Moreno, Carlos

2011-01-01

To establish the quality of waters it is necessary to identify both point and non-point pollution sources. In this work, we propose the combination of clean analytical methodologies and chemometric tools to study discrete and diffuse pollution caused in a river by tributaries and precipitations, respectively. During a two-year period, water samples were taken in the Guadalquivir river (selected as a case study) and its main tributaries before and after precipitations. Samples were characterized by analysing nutrients, pH, dissolved oxygen, total and volatile suspended solids, carbon species, and heavy metals. Results were used to estimate fluvial and atmospheric inputs and as tracers for anthropic activities. Multivariate analysis was used to estimate the background pollution, and to identify pollution inputs. Principal Component Analysis and Cluster Analysis were used as data exploratory tools, while box-whiskers plots and Linear Discriminant Analysis were used to analyse and distinguish the different types of water samples. - Highlights: → Atmospheric and fluvial inputs of pollutants in Guadalquivir River were identified. → Point (tributary rivers) and non-point sources (rains) were studied. → Nature and extension of anthropogenic pollution in the river were established. - By combining trace environmental analysis and selected chemometric tools atmospheric and fluvial inputs of pollutants in rivers may be identified. The extension of the pollution originated by each anthropic activity developed along the River may be established, as well as the identification of the pollution introduced into the river by the tributary rivers (point sources) and by rains (non-point sources).

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal - Appendix); FINAL

International Nuclear Information System (INIS)

Bou-Mikael, Sami

2002-01-01

The main objective of the Port Neches Project was to determine the feasibility and producibility of CO2 miscible flooding techniques enhanced with horizontal drilling applied to a Fluvial Dominated Deltaic reservoir. The second was to disseminate the knowledge gained through established Technology Transfer mechanisms to support DOE's programmatic objectives of increasing domestic oil production and reducing abandonment of oil fields

Environmental and ecological architects: Guidelines for the Chilean temperate rainforest management derived from the monito del monte (Dromiciops gliroides conservation Arquitectos ambientales y ecológicos: Pautas para la gestión ambiental del bosque templado lluvioso de Chile derivadas de la conservación del monito del monte (Dromiciops gliroides

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FRANCISCO E FONTÚRBEL

2011-06-01

Full Text Available Land use change is one of the main biodiversity threats. Due to this change, natural habitats such as the South American temperate rainforests have been rapidly degraded, fragmented, and lost. Consequently, the management and conservation of the remaining forest is a priority and having an appropriate environmental policy is mandatory for this purpose. Conservation actions in the temperate rainforest have been addressed from an individual species perspective, giving less attention to the ecosystem level conservation. Moreover, conservation-related information has not reflected yet on environmental policy development. We used the case study of the monito del monte (Dromiciops gliroides to illustrate how our current ecological and conservation knowledge of a species could be used to generate a new environmental policy. Dromiciops gliroides is a forest-dependent species with an important ecological role and quite unique evolutionary status. In order to guarantee the persistence of D. gliroides, we propose two habitat management components to be incorporated in management plans: structure and connectivity. Structure refers to spatial arrangement and key structural elements that determine habitat quality and connectivity refers to functional connectivity at the landscape level. The conservation of the monito del monte might also contribute to the conservation of many other forest-dependent species. By conserving such species it will be possible to conserve the ecological interactions and the eco-evolutionary processes, which ultimately determine the conservation of the temperate rainforest.El cambio de uso de la tierra es una de las principales amenazas a la biodiversidad. Hábitats naturales como el bosque templado lluvioso de Sudamérica han sido degradados, fragmentados y eliminados rápidamente. En consecuencia, es prioritario el manejo y conservación de los remanentes, para lo que es necesario contar con una política ambiental acorde. Las

Fluvial terrace formation in the northern Upper Rhine Graben during the last 20 000 years as a result of allogenic controls and autogenic evolution

NARCIS (Netherlands)

Erkens, G.; Dambeck, R.; Volleberg, K.P.; Bouman, M.I.T.J.; Bos, J.A.A.; Cohen, K.M.; Hoek, W.Z.

2009-01-01

The northern Upper Rhine Graben hosts a well-preserved Late Weichselian and Holocene fluvial terrace sequence. Terraces differ in elevation, morphology, and overbank sediment characteristics. The purpose of this study was to determine the relative importance of allogenic controlling factors versus

Inventario de las aves de un bosque altoandino: comparación de dos métodos

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Stiles Hurd Frank Galfierd

1998-06-01

Full Text Available Capturing birds with mist-nets has been the sole method used or proposed for making species inventories of several Neotropical forests, but this method has rarely been evaluated relative to the use of visual and auditory observations in these forests. This study compares the effectiveness and efficiency of these two methods in the elaboration of the list of bird species on a 15 ha study plot of forest and subparamo vegetation in the Eastern Andes of Colombia. Over ten months we made 11 visits of 4-6 days each, observing and running nets along ca. 3 km of study trails. Of 102 total species recorded, 101 were observed and 50 captured; 52 were observed but not captured vs. only one that was only recorded with the nets. The observations were more efficient in accumulating species, with a mean of 68.4 per visit vs. 17.1 species captured. More than half of the species observed had been recorded after a single visit, and over 90% in six visits; the corresponding figures for mist-net captures were four and nine visits. Compared with the totallist, the mist net sample was biased towards small species « 50 g; some diet groups or foraging guilds were over- or underrepresented in this sample. We conclude that visual and auditory observations are more effective and efficient for making inventories of birds in these forests. Mist nets are a useful supplement to these observations, but not a substitute; their greatest utility lies in obtaining other sorts of data.La captura con redes de niebla ha sido utilizada o propuesta como método único para realizar inventarios de aves en varios bosques neotropicales, pero pocas veces ha sido evaluado en este medio en relación a otros métodos como el de las observaciones visuales y auditivas. Este estudio compara la efectividad y eficiencia de estos dos métodos en la elaboración de la lista de las especies de aves de una parcela de 15 ha de bosque altoandino y subpáramo en la Cordillera Oriental de Colombia

Preliminary technical and economic viability for the implantation of fluvial transport of CNG (Compressed Natural Gas) for barges in Amazon Region; Avaliacao preliminar de viabilidade tecnico-economica para implantacao de transporte fluvial de GNC (Gas Natual Comprimido) por barcacas na Regiao Amazonica

Energy Technology Data Exchange (ETDEWEB)

Araujo, Marcos C.C. de; Porto, Paulo L. Lemgruber [Interocean Engenharia e Ship Management, Rio de janeiro, RJ (Brazil); Cunha, Rafael H. da [Metro Rio, RJ (Brazil); Garcia, Rafael M. [Pic Brasil (Brazil); Almeida, Marco A.R. de [Universidade Gama Filho (UGF), Rio de Janeiro, RJ (Brazil)

2004-07-01

The isolated regions of the Amazon present difficulties for integration with the electrical system which is creating some economic problems due to the consequent costs of electric generation of subsidies as a function of the fossil fuel use as oils diesel and fuel. A viable option is the use of Natural Gas - NG that is Also available in the region. Its modal of transport possible in the Region North they are for gas-lines or barges. The Compressed Natural Gas transport is distinguished that - CNG for barges was still not tested operationally in Brazil. Soon, to develop a Preliminary Study of Viability Technician - Economic - SVTE for the implantation of fluvial transport of CNG between the cities of Coari and Manaus is basic, therefore it is created strategical alternative for the electric generation in this region. The electric sector, the characteristics of the NG and the transport in this region had been analyzed to support to the work. The gas line and the fluvial transport of CNG for barges in this region are not conflicting, and they in a complementary form can act. The SVTE presented a Liquid Present Value and Internal Tax of very attractive Return justifying its implantation. (author)

Sediment Budget in the Taiwan Strait with High Fluvial Sediment Inputs from Mountainous Rivers: New Observations and Synthesis

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Shuh-Ji Kao

2008-01-01

Full Text Available The shallow Taiwan Strait at the southern opening of the East China Sea (ECS receives abundant sediments from turbid mountainous rivers in Taiwan. The volume of sediment is among the highest sediment yields on the global surface. This large amount of sediment discharged from modern Taiwan (range: 175 - 380 Mt y-1 based on 50-yr data is comparable to that discharged from Changjaing (500 Mt y-1-decreasing in recent decades, underscoring the importance of sediment budget in the Taiwan Strait and sediment flux from Taiwan into the ECS.We documented fluvial mud and sand concentrations during flash flooding with our observations indicating that fluvial materials in Taiwan¡¦s rivers are chiefly composed of mud (> 70 and up to 98 . By contrast, sand fraction dominates (> 85 for most stations surface sediments in the Taiwan Strait. Super typhoon Herb alone delivered 130 Mt of sediments from Choshui, the largest river in Taiwan, yet only insignificant amounts of mud were found at the river mouth six months later. The actions of waves, tides, and currents apparently prevent the deposition of fine grained sediments. Assuming sand occupied 30 (the maximum of the 60 Mt y-1 total sediment input from major western Taiwanese rivers, our annual budget estimate shows that the amount of sand input (18 5 Mt y-1 is comparable to the burial output of sand (12 10 Mt y-1. However, mud burial (6 5 Mt y-1 in the strait is far below the estimated mud input (42 11 Mt y-1, resulting in a significant shortfall. Hydrodynamic conditions were synthesized to explain the distribution pattern of limited mud patches in the strait and to reveal potential pathways by which fine-grain sediment transportation takes place in the seas surrounding Taiwan. A significant shortfall in the mud budget in the Taiwan Strait suggests that ~85 of the fluvial mud left the strait. Alternatively, the 50-year modern sediment flux data used in this study reflects exacerbated sediment flux due to human

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal), Class I; FINAL

International Nuclear Information System (INIS)

Bou-Mikael, Sami

2002-01-01

This project outlines a proposal to improve the recovery of light oil from waterflooded fluvial dominated deltaic (FDD) reservoir through a miscible carbon dioxide (CO2) flood. The site is the Port Neches Field in Orange County, Texas. The field is well explored and well exploited. The project area is 270 acres within the Port Neches Field

CAMBIOS A CORTO PLAZO EN LOS PATRONES DE DISTRIBUCIÓN ESPACIAL DE NUEVE ESPECIES DE PLANTAS COMUNES EN UN BOSQUE NUBLADO AL SUR-OCCIDENTE DE COLOMBIA

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Vallejo Martha

2009-06-01

Full Text Available Se analizaron los cambios en los patrones de distribución espacial de nueve especies de plantas comunes en un bosque pluvial premontano, entre dos censos realizados en una parcela permanente de 25 ha. Durante el primer censo efectuado en 1997 se marcaron, se midieron y se ubicaron en un mapa, todos los tallos leñosos con un DAP ≥ 1 cm; transcurridos cinco años se realizó un segundo censo y se incluyeron datos de mortalidad y reclutamiento. Mediante pruebas de estadística espacial usando la función K(t de Ripley, se detectaron los patrones de distribución de las especies estudiadas y las relaciones de dependencia de dos tipos de eventos: árboles grandes (DAP ≥ 10cm vs. árboles pequeños (DAP

Quaternary Morphodynamics of Fluvial Dispersal Systems Revealed: The Fly River, PNG, and the Sunda Shelf, SE Asia, simulated with the Massively Parallel GPU-based Model 'GULLEM'

Science.gov (United States)

Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Best, J.; Dietrich, W. E.

2015-12-01

During glacial-marine transgressions vast volumes of sediment are deposited due to the infilling of lowland fluvial systems and shallow shelves, material that is removed during ensuing regressions. Modelling these processes would illuminate system morphodynamics, fluxes, and 'complexity' in response to base level change, yet such problems are computationally formidable. Environmental systems are characterized by strong interconnectivity, yet traditional supercomputers have slow inter-node communication -- whereas rapidly advancing Graphics Processing Unit (GPU) technology offers vastly higher (>100x) bandwidths. GULLEM (GpU-accelerated Lowland Landscape Evolution Model) employs massively parallel code to simulate coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. GULLEM models the accommodation space carved/infilled by representing a range of geomorphic processes, including: river & tributary incision within a multi-directional flow regime, non-linear diffusion, glacial-isostatic flexure, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, and full 3D tracking of all resulting stratigraphy. Model results concur with the Holocene dynamics of the Fly River, PNG -- as documented with dated cores, sonar imaging of floodbasin stratigraphy, and the observations of topographic remnants from LGM conditions. Other supporting research was conducted along the Mekong River, the largest fluvial system of the Sunda Shelf. These and other field data provide tantalizing empirical glimpses into the lowland landscapes of large rivers during glacial-interglacial transitions, observations that can be explored with this powerful numerical model. GULLEM affords estimates for the timing and flux budgets within the Fly and Sunda Systems, illustrating complex internal system responses to the external forcing of sea level and climate. Furthermore, GULLEM can be applied to most ANY fluvial system to

Paleogeographic and Depositional Model for the Neogene fluvial succession, Pishin Belt Northwest Pakistan

DEFF Research Database (Denmark)

Kasi, Aimal Khan; Kassi, Akhtar Muhammad; Umar, Muhammad

2017-01-01

Miocene subaerial sedimentation started after the final closure of Katawaz Remnant Ocean. Based on detailed field data twelve facies were recognized in Neogene successions exposed in Pishin Belt. These facies were further organized into four facies associations i.e. channels, crevasse splay, natural levee...... and floodplain facies associations. Facies associations and variations provided ample evidences to recognize number of fluvial architectural components in the succession e.g., low-sinuosity sandy braided river, mixed-load meandering, high-sinuosity meandering channels, single-story sandstone and/or conglomerate...... channels, lateral accretion surfaces (point bars) and alluvial fans. Neogene sedimentation in the Pishin Belt was mainly controlled by active tectonism and thrusting in response to oblique collision of the Indian Plate with Afghan Block of the Eurasian Plate along the Chaman-Nushki Fault. Post Miocene...

Inputs and Fluvial Transport of Pharmaceutical Chemicals in An Urban Watershed

Science.gov (United States)

Foster, G. D.; Shala, L.

2006-05-01

Pharmaceuticals and personal care products (PPCPs) are classes of emerging chemical contaminants thought to enter the aquatic environment primarily through wastewater treatment plant (WTP) discharges. As the use of drugs is expected to rise with the aging demographics of the human population and with more river water being diverted to meet potable water demands, the presence of PPCPs in surface water is becoming an issue of public concern. The intent of our study was to quantify potential WTP inputs of PPCPs to rivers in the Wasington, DC (USA) region, and to investigate the fluvial transport of PPCPs in the Anacostia River (AR), the mainstem of a highly contaminated urban watershed in Washington, DC. The approach was to sample WTP water at various stages of treatment, and to measure seasonal concentrations of PPCPs in fluvial transport in the AR. Surface water from the AR was collected through the use of automated samplers during normal flow and storm flow regimes near the head of tide of the AR, just upstream from the confluence of the Northeast (NE) and Northwest (NW) Branches, the two prominent drainages in the watershed. The water samples were filtered to separate river particles from water, and the filtered water was extracted using solid phase extraction (SPE) cartridges. The filters were extracted by sonication in methanol. The SPE and filter extracts were analyzed for a group of widely distributed PPCPs as trimethylsilyl derivatives by using gas chromatography/mass spectrometry. The most frequently detected PPCPs at WTPs included ibuprofen, caffeine, naproxen and triclosan, which ranged from 45 μg/L (caffeine) to 5 μg/L (triclosan) in WTP influent and from 0.08 μg/L (triclosan) to 0.02 μg/L (ibuprofen) in effluent water. Similar PPCPs were detected in both the NE and NW Branches of the AR, but higher concentrations on average were observed in the NE Branch, which receives WTP effluent upstream from the sampling point. The incidence of PPCPs correlated

Which DEM is best for analyzing fluvial landscape development in mountainous terrains?

Science.gov (United States)

Boulton, Sarah J.; Stokes, Martin

2018-06-01

Regional studies of fluvial landforms and long-term (Quaternary) landscape development in remote mountain landscapes routinely use satellite-derived DEM data sets. The SRTM and ASTER DEMs are the most commonly utilised because of their longer availability, free cost, and ease of access. However, rapid technological developments mean that newer and higher resolution DEM data sets such as ALOS World 3D (AW3D) and TanDEM-X are being released to the scientific community. Geomorphologists are thus faced with an increasingly problematic challenge of selecting an appropriate DEM for their landscape analyses. Here, we test the application of four medium resolution DEM products (30 m = SRTM, ASTER, AW3D; 12 m = TanDEM-X) for qualitative and quantitative analysis of a fluvial mountain landscape using the Dades River catchment (High Atlas Mountains, Morocco). This landscape comprises significant DEM remote sensing challenges, notably a high mountain relief, steep slopes, and a deeply incised high sinuosity drainage network with narrow canyon/gorge reaches. Our goal was to see which DEM produced the most representative best fit drainage network and meaningful quantification. To achieve this, we used ArcGIS and Stream Profiler platforms to generate catchment hillshade and slope rasters and to extract drainage network, channel long profile and channel slope, and area data. TanDEM-X produces the clearest landscape representation but with channel routing errors in localised high relief areas. Thirty-metre DEMs are smoother and less detailed, but the AW3D shows the closest fit to the real drainage network configuration. The TanDEM-X elevation values are the closest to field-derived GPS measurements. Long profiles exhibit similar shapes but with minor differences in length, elevation, and the degree of noise/smoothing, with AW3D producing the best representation. Slope-area plots display similarly positioned slope-break knickpoints with modest differences in steepness and concavity

Contrasting styles of aeolian, fluvial and marine interaction in the Cutler Group of the Paradox Basin, SE Utah, USA

OpenAIRE

Wakefield, Oliver; Mountney, Nigel

2017-01-01

The Permian-Pennsylvanian Cutler Group of the Paradox foreland basin of southeast Utah is characterised by a variety of styles of interaction between coeval aeolian, fluvial and marine environments that have resulted in the generation and preservation of a complex suite of stratal architectures. Detailed 3D architectural element analysis has enabled the nature of these interactions to be interpreted in order to constrain both the spatial and temporal scale over which competing ...

Plántulas de algunas especies leñosas nativas y connaturalizadas del bosque subandino Silvania- Cundinamarca- Colombia

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Barrera Torres Eduardo

1992-06-01

Full Text Available Con el propósito de identificar, en el medio natural, los primeros estadios de crecimiento de algunas especies de árboles y arbustos representativps de la franja inferior del Bosque Subandino, se describen las plántulas de 45 taxa de Dicotiledóneas, obtenidas mediante la germinación de semillas en condiciones de vivero semidescubierto. Entre otros caracteres observados, útiles para el reconocimiento taxonómico, se cuentan las modalidades de germinación, la estructuración y organización de los cotiledones, del hipocotilo y el epicotilo, complementados con la determinación de la filotaxis y la diferenciación foliar. Las familias con mayor número de especies estudiadas corresponden a los ordenes Fabales y Myrtales , con 13 y 6 especies, respectivamente.In order to identify in the natural medium the first growth sta tes of some trees and ahrubs represented on the inferiorfringe of the andino woods, 45 taxa of Dicotyledons seedlings are described, obtained through germination of seeds under semigreenhouse conditions. Among other characters observed which are used for taxonomic identification are: The germination, structure and organization of the Cotyledons, hypocotyl, andepicotyl coupled with the determination of the filotaxis and leaf diferentiation. The familias of the higher species studied
correspond to the orders: Fabales and Myrtales, whith 13 and 6 species respectively.