WorldWideScience

Sample records for surface subsidence due

  1. Assessment, management rehabilitation of surface water losses due to longwall coal mining subsidence

    Energy Technology Data Exchange (ETDEWEB)

    Dawkins, A.P. [Coffey Geosciences Pty. Ltd., Sydney, NSW (Australia)

    1999-07-01

    Subsidence due to longwall coal mining has generated notable effects on surface water and groundwater above numerous longwall coal mines in Queensland and NSW. This paper deals with the methods which can be used to assess, predict and rehabilitate the effects of longwall surface subsidence on surface water bodies. Aspects discussed cover the subsidence model, hydrological and hydrogeological assessment, hydrogeochemical changes and subsidence rehabilitation issues. The paper concludes that longwall surface subsidence can significantly affect the mine's local environment. However, with sufficient baseline data and a thorough assessment of site specific issues, longwalls can be planned to account for subsidence effects on surface water, and possible deleterious effects can be mitigated. 20 refs., 4 figs.

  2. Time-dependent inversion of surface subsidence due to dynamic reservoir compaction

    NARCIS (Netherlands)

    Muntendam-Bos, A.G.; Kroon, I.C.; Fokker, P.A.

    2008-01-01

    We introduce a novel, time-dependent inversion scheme for resolving temporal reservoir pressure drop from surface subsidence observations (from leveling or GPS data, InSAR, tiltmeter monitoring) in a single procedure. The theory is able to accommodate both the absence of surface subsidence estimates

  3. Failure of man-made cavities in salt and surface subsidence due to sulfur mining

    Energy Technology Data Exchange (ETDEWEB)

    Coates, G.K.; Lee, C.A.; McClain, W.C.; Senseny, P.E.

    1981-01-01

    An engineering data base relevant to subsidence due to sulfur mining and to structural failure of cavities in salt is established, evaluated and documented. Nineteen failure events are discussed. Based on these documented failure events, capabilities of and inputs to a mathematical model of cavity failure are determined. Two failure events are adequately documented for use in model verification studies. A conclusion of this study that is pertinent to the Strategic Petroleum Reserve is that cavity failures in dome salt are fairly rare, but that as the number of large cavities (especially those having large roof spans) increases, failures will probably be more common unless stability and failure mechanisms of cavities are better understood.

  4. Subsidence due to geothermal fluid withdrawal

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, T. N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Univ. of California, Berkeley, CA (United States); Goyal, K. P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Univ. of California, Berkeley, CA (United States)

    1984-12-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the United States, and elsewhere. Vertical ground displacements of up to 4.5 m and horizontal ground displacements of up to 0.5 m have been observed at Wairakei, New Zealand, that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy, and Cerro Prieto, Mexico. In this paper, observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence, and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant thermal mechanisms. Finally, although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  5. Subsidence due to geothermal fluid withdrawal

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, T.N.; Goyal, K.P.

    1982-10-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the U.S. and elsewhere. Vertical ground displacements of upto 4.5 m and horizontal ground displacements of up t o 0.5 m have been observed at Wairakei, New Zealand that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy and Cerro Prieto, Mexico. Observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant therma mechanisms. Although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  6. Coastal Flooding Hazards due to storm surges and subsidence

    DEFF Research Database (Denmark)

    Sørensen, Carlo; Knudsen, Per; Andersen, Ole B.

    Flooding hazard and risk mapping are major topics in low-lying coastal areas before even considering the adverse effects of sea level rise (SLR) due to climate change. While permanent inundation may be a prevalent issue, more often floods related to extreme events (storm surges) have the largest...... damage potential.Challenges are amplified in some areas due to subsidence from natural and/or anthropogenic causes. Subsidence of even a few mm/y may over time greatly impair the safety against flooding of coastal communities and must be accounted for in order to accomplish the economically most viable...

  7. Linking oil production to surface subsidence from satellite radar interferometry

    Science.gov (United States)

    Xu, Haibin; Dvorkin, Jack; Nur, Amos

    Land subsidence over the Belridge and Lost Hills oil fields, Southern California, was measured using spaceborne interferometric synthetic aperture radar (InSAR). During the 105-day period between 11/5/95 and 2/17/96, the subsidence in the center of the Lost Hills field reached 15 cm. We assume that this surface subsidence resulted from the vertical shrinkage of the reservoir, which in turn was due to oil production and the resulting pore pressure drop. We model this mechanical effect using an elastic deformation theoretical solution with input constants taken from relevant experiments. The modeled surface deformation matches the InSAR measured values. This result indicates that it is possible, in principle, to monitor hydrocarbon production using satellite-based measurements of earth deformation.

  8. Genetic Programming Approach for Predicting Surface Subsidence Induced by Mining

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The surface subsidence induced by mining is a complex problem, which is related with many complex and uncertain factors.Genetic programming (GP) has a good ability to deal with complex and nonlinear problems, therefore genetic programming approach is proposed to predict mining induced surface subsidence in this article.First genetic programming technique is introduced, second, surface subsidence genetic programming model is set up by selecting its main affective factors and training relating to practical engineering data, and finally, predictions are made by the testing of data, whose results show that the relative error is approximately less than 10%, which can meet the engineering needs, and therefore, this proposed approach is valid and applicable in predicting mining induced surface subsidence.The model offers a novel method to predict surface subsidence in mining.

  9. Subsidence due to Excessive Groundwater Withdrawal in the San Joaquin Valley, California

    Science.gov (United States)

    Corbett, F.; Harter, T.; Sneed, M.

    2011-12-01

    Francis Corbett1, Thomas Harter1 and Michelle Sneed2 1Department of Land Air and Water Resources, University of California, Davis. 2U.S. Geological Survey Western Remote Sensing and Visualization Center, Sacramento. Abstract: Groundwater development within the Central Valley of California began approximately a century ago. Water was needed to supplement limited surface water supplies for the burgeoning population and agricultural industries, especially within the arid but fertile San Joaquin Valley. Groundwater levels have recovered only partially during wet years from drought-induced lows creating long-term groundwater storage overdraft. Surface water deliveries from Federal and State sources led to a partial alleviation of these pressure head declines from the late 1960s. However, in recent decades, surface water deliveries have declined owing to increasing environmental pressures, whilst water demands have remained steady. Today, a large portion of the San Joaquin Valley population, and especially agriculture, rely upon groundwater. Groundwater levels are again rapidly declining except in wet years. There is significant concern that subsidence due to groundwater withdrawal, first observed at a large scale in the middle 20th century, will resume as groundwater resources continue to be depleted. Previous subsidence has led to problems such as infrastructure damage and flooding. To provide a support tool for groundwater management on a naval air station in the southern San Joaquin Valley (Tulare Lake Basin), a one-dimensional MODFLOW subsidence model covering the period 1925 to 2010 was developed incorporating extensive reconstruction of historical subsidence and water level data from various sources. The stratigraphy used for model input was interpreted from geophysical logs and well completion reports. Gaining good quality data proved problematic, and often values needed to be estimated. In part, this was due to the historical lack of awareness/understanding of

  10. Areas of ground subsidence due to geofluid withdrawal

    Energy Technology Data Exchange (ETDEWEB)

    Grimsrud, G.P.; Turner, B.L.; Frame, P.A.

    1978-08-01

    Detailed information is provided on four geothermal areas with histories of subsidence. These were selected on the basis of: physical relevance of subsidence areas to high priority US geothermal sites in terms of withdrawn geofluid type, reservoir depth, reservoir geology and rock characteristics, and overburden characteristics; and data completeness, quality, and availability. The four areas are: Chocolate Bayou, Raft River Valley, Wairakei, and the Geysers. (MHR)

  11. Modeling Surface Subsidence from Hydrocarbon Production and Induced Fault Slip in the Louisiana Coastal Zone

    Science.gov (United States)

    Mallman, E. P.; Zoback, M. D.

    2005-12-01

    Coastal wetland loss in southern Louisiana poses a great threat to the ecological and economic stability of the region. In the region of interest, wetland loss is a combination of land subsidence along with eustatic sea level rise, sediment accumulation, erosion, filling and drainage. More than half of the land loss in coastal Louisiana between 1932 and 1990 was related to subsidence due to the complicated interaction of multiple natural and anthropogenic processes, including compaction of Holocene sediments in the Mississippi River delta, lithospheric flexure as a response to sediment loading, and natural episodic movement along regional growth faults. In addition to these mechanisms, it has recently been suggested that subsurface oil and gas production may be a large contributing factor to surface subsidence in the Louisiana Coastal Zone. We model the effect of fluid withdrawal from oil and gas fields in the Barataria Bay region of the Louisiana Coastal Zone on surface subsidence and its potential role in inducing fault slip on the region's growth faults. Along the western edge of Barataria Basin is a first-order leveling line to constrain our model of land subsidence. The rates for this leveling line show numerous locations of increased subsidence rate over the surrounding area, which tend to be located over the large oil and gas fields in the region. However, also located in the regions of high subsidence rate and oil and gas fields are the regional normal faults. Slip on these growth faults is important in two contexts: Regional subsidence would be expected along these faults as a natural consequence of naturally-occurring slip over time. In addition, slip along the faults can be exacerbated by production such that surface subsidence would be localized near the oil and gas fields. Using pressure data from wells in the Valentine, Golden Meadow, and Leeville oil and gas fields we estimate the amount of compaction of the various reservoirs, the resulting surface

  12. Surface subsidence induced by the Crandall Mine (Utah) collapse: InSAR observations and anelastic modeling

    Science.gov (United States)

    Plattner, C.; Wdowinski, S.; Dixon, T. H.; Govers, R. M.

    2009-12-01

    The Crandall Mine collapsed in August 2007 and resulted in the death of 6 miners. The collapse induced surface subsidence visible by satellite geodesy. We processed data from ALOS satellite acquired before and after the collapse to quantify the subsidence and infer the deformation at depth. Our InSAR results show a localized oval shaped (1000 x 500 m2) pattern of subsidence with a maximum vertical displacement of 29 cm. Profiles across the subsided area show a steep V-shaped pattern. We first model the collapse using an elastic halfspace model. However, we find poor agreement between the elastic model solution and the InSAR observations, mainly because the elastic solution is characterized by a broad subsidence pattern, as elasticity does not explain localized strain. To overcome this limitation, we investigated analytical models that consider strain localization due to material failure. Here, we apply a model predicting surface settlement from tunneling (Loganathan and Poulos, 1998). This model uses the internal friction angle to define the maximum width of the subsidence area. To account for the flat shape of the collapse strata, we modify the model by changing its geometry from circular shape to elliptical (500 x 2.4 m). Our results show a very good fit in terms of the subsidence pattern, in particular the localization of the subsidence. We found that the surface subsidence was caused by a 7.7% collapse of the mine elliptical shaped mine. Although our simple model does not explain all the observed features, we find it more suitable than elastic halfspace models to explain the localized deformation pattern.

  13. Analysis of elastoplasticity and rheology due to mining subsidence

    Institute of Scientific and Technical Information of China (English)

    WU Xiong; WANG XiaoGang; DUAN QingWei; JIA ZhiXin; XU NengXiong; SUN YanDong

    2008-01-01

    At present, as the easily mining resources are being increasingly depleted, the exploitation of coal under buildings, water-bodies and railways is imminent for the sustainable production. Probability in-tegral method is a general method for mining subsidence in the coal system. Because of poor under-standing of mining subsidence for other sections, the authors suggest probability integral method for the study of coal mining under buildings, water-bodies and railways. Moreover, the calculation result of probability integral method should be corrected by numerical simulation method. Based on practical projects, the impact has been evaluated on the security of Xifeihe left embankment under coal mining. Combining with the results of probability integral method, we propose that the 600 m far from em-bankment is a good rationality. This article provides the basis for the rational exploitation of coal re-source which is a major practical problem under the premise of Water Infrastructure Security. Fur-thermore, it also can be served as a reference for the similar projects, such as mining Xiaolangdi res-ervoir area, mining Yuecheng reservoir and mining the major channels of Middle Route South to North Water Transfer.

  14. Numerical analysis of surface subsidence in asymmetric parallel highway tunnels

    Directory of Open Access Journals (Sweden)

    Ratan Das

    2017-02-01

    Full Text Available Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, Kainchi-mod Nerchowck twin tunnels (Himachal Pradesh, India are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and in-equidimensional noncircular tunnel.

  15. Monitoring on subsidence due to repeated excavation with DInSAR technology

    Institute of Scientific and Technical Information of China (English)

    Liu Zhenguo; Bian Zhengfu; Lü Fuxiang; Dong Baoquan

    2013-01-01

    DInSAR technology was used to monitor subsidence caused by underground coal mining activities in mountainous area,with multi source SAR data,including 8 EnviSAT C-band and 4 ALOS L-band,and 4 programmed TerraSAR-X dataset.The results revealed that 2-pass DInSAR technique sometimes failed to retrieve the mining-caused subsidence due to spatial and/or temporal de-correlation.We also noticed that there existed residual topographic phase after the compensation with SRTM DEM,which could almost overwhelm the subsidence information when the perpendicular baseline was relatively large.Based on the mining materials,analysis was made on the shape of subsidence area.For the well geocoded results from TerraSAR-X,confirmed by GPS surveying results of corner reflectors,we tried to extract the advance distance of influence besides the subsidence area.Due to the big deformation gradient over stopingfaces,the X-band SAR data could not capture the maximum value subsidence revealed by GPS survey in our preliminary results,the same as C-band EnviSAT data.This will turn to be our research subject in the next few months.

  16. On Assessment and Estimation of Potential Losses due to Land Subsidence in Urban Areas of Indonesia

    Science.gov (United States)

    Abidin, Hasanuddin Z.; Andreas, Heri; Gumilar, Irwan; Sidiq, Teguh P.

    2016-04-01

    Land subsidence is natural-anthropogenic hazard affecting several large urban areas in Indonesia, i.e. Jakarta, Bandung and Semarang. Geodetic based results from various techniques (e.g. Leveling, GPS and InSAR) show that land subsidence rates in all three cities generally have spatial and temporal variations, and their magnitude is in average about 5-10 cm/year. The impacts of subsidence in those cities can be seen in the field in various forms such as cracking of permanent constructions and roads, tilting of houses and buildings, 'sinking' of houses and buildings, changes in river canal and drain flow systems, wider expansion of coastal and/or inland flooding areas, and increased inland sea water intrusion. These impacts can be categorized into infrastructure, environmental, economic, and social impacts. The potential losses due to land subsidence in urban areas are actually quite significant. Related infrastructural, social and environmental costs due to direct and indirect impacts of land subsidence are economically quite significant, and can not be underestimated in sustainable urban development. The planning, development and maintenance costs of building and infrastructures in the affected areas are usually much higher than the normal situation. The collateral impact of coastal subsidence in Jakarta and Semarang, in the form of coastal flooding during high tides is also quite damaging. This repeated coastal flooding in several areas along the coast will deteriorate the structure and function of building and infrastructures, badly influences the quality of the living environment and life (e.g. health and sanitation condition), and also disrupts economic and social activities in the affected areas. As in the case of Bandung, inland subsidence also has a quite significant impact on inland flooding phenomena, since it will theoretically lead to expanded coverage and deeper water depth of flooded (inundated) areas. Since the direct and indirect impacts of

  17. Computer program for predicting surface subsidence resulting from pressure depletion in geopressured wells: subsidence prediction for the DOW test well No. 1, Parcperdue, Louisiana

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, J.C.; Carver, D.R.; Bebout, D.G.; Bachman, A.L. (eds.)

    1981-01-01

    The nucleus-of-strain concept is used to construct a computer program for predicting surface subsidence due to pressure reduction in geopressured reservoirs. Numerical integration allows one to compute the vertical displacement of the ground surface directly above and beyond the aquifer boundaries which results from the pressure reduction in each of the small finite volumes into which the aquifer is partitioned. The program treats depth (measured from the surface to the mean thickness of the aquifer) as a constant. Variation in aquifer thickness is accounted for by linear interpolation from one boundary to its opposite. In this simple model, subsidence is proportional to the pressure reduction (considered constant in this presentation) and to but one physical parameter, Cm(1-..nu..), in which Cm is its coefficient of uniaxial compaction, and ..nu.. is Poisson's ratio.

  18. Research on the surface subsidence monitoring technology based on fiber Bragg grating sensing

    Science.gov (United States)

    Wang, Jinyu; Jiang, Long; Sun, Zengrong; Hu, Binxin; Zhang, Faxiang; Song, Guangdong; Liu, Tongyu; Qi, Junfeng; Zhang, Longping

    2017-03-01

    In order to monitor the process of surface subsidence caused by mining in real time, we reported two types of fiber Bragg grating (FBG) based sensors. The principles of the FBG-based displacement sensor and the FBG-based micro-seismic sensor were described. The surface subsidence monitoring system based on the FBG sensing technology was designed. Some factual application of using these FBG-based sensors for subsidence monitoring in iron mines was presented.

  19. Subsidence due to fluid withdrawal: a survey of analytical capabilities. [1225 citations

    Energy Technology Data Exchange (ETDEWEB)

    Engi, D.

    1985-08-01

    An extensive review of the literature was conducted in the area of land subsidence due to the withdrawal of fluids. A method of categorizing the citations was developed to facilitate identification of references relating to specific fields of interest. A brief review of the materials represented by the bibliography indicates the state-of-the-art within this area. The bibliography (containing 1225 citations) is presented in its categorized form. 5 figs., 3 tabs.

  20. Reactivation of subsidence zones due to coal-mine closure in Donbass

    Energy Technology Data Exchange (ETDEWEB)

    Yermakov, V.N. [Ministry of Coal Industry, Donetsk (Ukraine)

    2000-12-01

    Many mines in the Ukraine are in the process of being closed as part of the coal industry restructuring programme. The termination of pumping operations results in the flooding of abandoned mine workings. This causes changes in the hydrogeological characteristics and geomechanical stability of the rock mass. There is no reliable method for predicting the effect of these processes. In the Central Donbass Basin, if only one mine horizon is flooded, surface subsidence of up to 500 mm can occur when the mine is abandoned. The period required for the stabilization of areas liable to subsidence after the mines are closed can be as long as 10 years. The mechanical properties of caved rock can change significantly during the long-term operation of coal mines in the Central Regions of Donbass. The mechanical properties of the rock can also change during flooding. It is therefore necessary to study the physical-mechanical properties of the caved strata when they are saturated during the flooding of abandoned workings. Research into methods of estimating the amount of additional surface subsidence caused by the reactivation of the geomechanical caving processes during flooding is reported.

  1. Subsidence due to gas production in the Wadden Sea: How to ensure no harm will be done to nature

    NARCIS (Netherlands)

    Thienen-Visser, K. van; Breunese, J.N.; Muntendam-Bos, A.G.

    2015-01-01

    The Wadden Sea is a shallow tidal sea in the north of the Netherlands where gas production is ongoing since 1986. Due to the sensitive nature of this area, gas extraction induced subsidence must remain within the "effective subsidence capacity" for the two tidal basins (Pinkegat and Zoutkamperlaag)

  2. Assessment of radar interferometry performance for ground subsidence monitoring due to underground mining

    Energy Technology Data Exchange (ETDEWEB)

    Ng, A.H.M.; Chang, H.C.; Ge, L.L.; Rizos, C.; Omura, M. [Cooperative Research Centre for Spatial Information, Carlton, Vic. (Australia)

    2009-07-01

    This paper describes the results from the recently launched SAR satellites for the purpose of subsidence monitoring over underground coal mine sites in the state of New South Wales, Australia, using differential interferometric synthetic aperture radar (DInSAR) technique. The quality of the mine subsidence monitoring results is mainly constrained by noise due to the spatial and temporal decorrelation between the interferometric pair and the phase discontinuities in the interferogram. This paper reports oil the analysis of the impact of these two factors on the performance of DInSAR for monitoring ground deformation. Simulations were carried out prior to real data analyses. SAR data acquired using different operating frequencies, for example, X-, C- and L-band, from the TerraSAR-X, ERS-1/2, ENVISAT, JERS-1 and ALOS satellite missions, were examined. The simulation results showed that the new satellites ALOS, TerraSAR-X and COSMO-SkyMed perform much better than the satellites launched before 2006. ALOS and ENVISAT satellite SAR images with similar temporal coverage were searched for the test site. The ALOS PALSAR DInSAR results have been compared to DInSAR results obtained from ENVISAT ASAR data to investigate the performance of both satellites for ground subsidence monitoring. Strong phase discontinuities and decorrelation have been observed in almost all ENVISAT interferograms and hence it is not possible to generate the displacement maps without errors. However these problems are minimal in ALOS PALSAR interferograms due to its spatial resolution and longer wavelength. Hence ALOS PALSAR is preferred for ground subsidence monitoring in areas covered by vegetation and where there is a high rate ground deformation.

  3. STUDY OF THE PIEZOMETRIC SURFACE AND HYDROCOMPACTION AT CONFINED AQUIFER CAUSED THE LAND SUBSIDENCE IN SEMARANG

    Directory of Open Access Journals (Sweden)

    Fahrudin Fahrudin

    2012-02-01

    Full Text Available Semarang city has experienced of the land subsidence that be caused by intake groundwater in confined aquiferabundant. The land subsidence happened during range of time 20 years, it’s critical boundary so that result theenvironmental damage. Hence needed a study of cause of the land subsidence. This study aim to know theposition of piezometric surface and also explain the mechanism hydrogeology when happened the landsubsidence. The study of spreading aquifer has been done by the analysis of secondary data which is in the formof drilling log data, piezometric surface and soil mechanics test obtained from PLG (Environmental Center ofGeology Bandung. Later then, between the land subsidence and piezometric surface be overlay becamezonation. From the data made a analysis of cause of the land subsidence. This aquifer has the land subsidence.The land subsidence explainable with the experienced phenomenon fact for example degradation of piezometricsurface at confined aquifer and process of hydrocompaction. That process influenced by two factors that areassess the pore number (e and specific gravity (Gs. The degradation of piezometric surface formed the trapezeof water table until 20 m from sea level with the mean 0.7 - 1.1 m/year. Hydrocompaction cause the degradationof number of mean pore 0.145 - 0.5 and specific gravity 0.009 - 0.073 . The degradation of piezometric surfaceand process the hydrocompaction cause the fast of land subsidence around 0.5 - 1.75 cm/year.

  4. Time function of surface subsidence based on Harris model in mined-out area

    Institute of Scientific and Technical Information of China (English)

    Liu Xinrong; Wang Junbao; Guo Jianqiang; Yuan Hong; Li Peng

    2013-01-01

    The surface subsidence is a common environmental hazard in mined-out area.Based on careful analysis of the regularity of surface subsidence in mined-out area,we proposed a new time function based on Harris curve model in consideration of the shortage of current surface subsidence time functions.By analyzing the characteristics of the new time function,we found that it could meet the dynamic process,the velocity change process and the acceleration change process during surface subsidence.Then its rationality had been verified through project cases.The results show that the proposed time function model can give a good reflection of the regularity of surface subsidence in mined-out area and can accurately predict surface subsidence.And the prediction data of the model are a little greater than measured data on condition of proper measured data quantity,which is safety in the engineering.This model provides a new method for the analysis of surface subsidence in mined-out area and reference for future prediction,and it is valuable to engineering application.

  5. Anelastic modeling of surface subsidence induced by the Crandall Mine (Utah) collapse

    Science.gov (United States)

    Plattner, Christina; Wdowinski, Shimon; Dixon, Tim

    2010-05-01

    The Crandall Mine collapsed in August 2007 and resulted in the death of 6 miners. The collapse induced surface subsidence visible by satellite geodesy. We processed data from ALOS satellite acquired before and after the collapse to quantify the subsidence and infer the deformation at depth. Our InSAR results show a localized oval shaped (1000 x 500 m2) pattern of subsidence with a maximum vertical displacement of 29 cm. Profiles across the subsided area show a steep V-shaped pattern. We first model the collapse using an elastic halfspace model. However, we find poor agreement between the elastic model solution and the InSAR observations, mainly because the elastic solution is characterized by a broad subsidence pattern. To improve this fit, we apply a model predicting surface settlement from tunneling (Loganathan and Poulos, 1998), where the internal friction angle is considered in the solution. To account for the flat shape of the collapse strata, we modify the model by changing its geometry from circular shape to elliptical (500 x 2.4 m). Our results show a very good fit in terms of the subsidence pattern, in particular the localization of the subsidence. We found that the surface subsidence was caused by a 7.7% collapse of the mine elliptical shaped mine. Although our simple model does not explain all the observed features, we find it more suitable than elastic halfspace models to explain the localized deformation pattern.

  6. Numerical modeling of land subsidence due to groundwater withdrawal in Aguascalientes Valley using regional coefficients of deformation determined by InSAR analysis.

    Science.gov (United States)

    Pacheco, J.; Cabral, E.; Wdowinski, S.; Hernandez-Marin, M.; Ortíz, J. Á.; Solano Rojas, D. E.; Oliver-Cabrera, T.

    2014-12-01

    Land subsidence due to groundwater over-exploitation is a deformation process affecting many cities around the world. This type of subsidence develops gradual vertical deformations reaching only a few centimeters per year, but can affect large areas. Consequently, inhabitants of subsiding areas are not aware of the process until others effects are observed, such as ground surface faulting, damage to building, or changes in the natural superficial drain. In order to mitigate and forecast subsidence consequences, it is useful to conduct numerical modeling of the subsidence process. Modeling the subsidence includes the following three basic tasks: a) Delimitation of the shape of the deforming body; b) Determination of the forces that are causing the deformations; and c) Determination of the mechanical properties of the deforming body according with an accepted rheological model. In the case of a land subsidence process, the deforming body is the aquifer system that is being drained. Usually, stratigraphic information from pumping wells, and other geophysical data are used to define the boundaries and shape of the aquifer system. The deformation governing forces, or stresses, can be calculated using the theory of "effective stress". Mechanical properties are usually determined with laboratory testing of samples from shallow strata, because the determination of these properties in samples from the deepest strata is economically or technically unviable. Consequently, the results of the numerical modeling do not necessarily match the observed subsidence evolution and ground faulting. We present in this work numerical simulation results of the land subsiding of the Valley of Aguascalientes, Mexico. Two analyses for the same subsiding area are presented. In the first of them, we used the mechanical properties of only the shallow strata, whereas in the second analysis we used "macroscopic" mechanical properties data determined for the whole aquifer system using In

  7. CHARACTERISTICS OF MOVEMENT OF SURFACE POINT IN DYNAMIC SUBSIDENCE BASIN AND ITS DEFORMATION CALCULATION

    Institute of Scientific and Technical Information of China (English)

    WANGShidao; HUANGPeizhu

    1995-01-01

    Along with underground mining, movement and deformation of overburden gradually extends in all directions and up to the ground surface and finally forms a surface subsidence basin. The surface movement progressively stabilizes until coal mining is completed and forms a stable movement basin. Two types of basins, i.e. static and dynamic subsidence basins are distinguished in the paper, a classification of the basins and a description of their characteristics are presented. Based on the analysis of measured data by Yanzhou Coal Mining Bureau, during mining operation, the movement characteristics of surface point, subsidence equation, subsidence rate equation and the law of distribution of movement parameters of surface point relative to principal section of movement basin are addressed in this paper. Moreover the calculating formula of the movement parameters for an arbitrary surface point and the expression for calculating the maximum subsidence rate are also proposed. On the basis of the findings, the movement deformation formula for an arbitrary surface point in any directions during mining operation is highlighted.

  8. Combination of poroelasticity theory and constant strain rate test in modelling land subsidence due to groundwater extraction

    Science.gov (United States)

    Pham, Tien Hung; Rühaak, Wolfram; Sass, Ingo

    2017-04-01

    Extensive groundwater extraction leads to a drawdown of the ground water table. Consequently, soil effective stress increases and can cause land subsidence. Analysis of land subsidence generally requires a numerical model based on poroelasticity theory, which was first proposed by Biot (1941). In the review of regional land subsidence accompanying groundwater extraction, Galloway and Burbey (2011) stated that more research and application is needed in coupling of stress-dependent land subsidence process. In geotechnical field, the constant rate of strain tests (CRS) was first introduced in 1969 (Smith and Wahls 1969) and was standardized in 1982 through the designation D4186-82 by American Society for Testing and Materials. From the reading values of CRS tests, the stress-dependent parameters of poroelasticity model can be calculated. So far, there is no research to link poroelasticity theory with CRS tests in modelling land subsidence due to groundwater extraction. One dimensional CRS tests using conventional compression cell and three dimension CRS tests using Rowe cell were performed. The tests were also modelled by using finite element method with mixed elements. Back analysis technique is used to find the suitable values of hydraulic conductivity and bulk modulus that depend on the stress or void ratio. Finally, the obtained results are used in land subsidence models. Biot, M. A. (1941). "General theory of three-dimensional consolidation." Journal of applied physics 12(2): 155-164. Galloway, D. L. and T. J. Burbey (2011). "Review: Regional land subsidence accompanying groundwater extraction." Hydrogeology Journal 19(8): 1459-1486. Smith, R. E. and H. E. Wahls (1969). "Consolidation under constant rates of strain." Journal of Soil Mechanics & Foundations Div.

  9. Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing

    Directory of Open Access Journals (Sweden)

    Jiming Guo

    2016-09-01

    Full Text Available The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR technique, which can simultaneously detect point-like stable reflectors (PSs and distributed scatterers (DSs, was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined.

  10. Systematic approach to assess and mitigate longwall subsidence influences on surface structures

    Institute of Scientific and Technical Information of China (English)

    LUO Yi

    2008-01-01

    The surface subsidence process associated with Iongwall mining operations isoften capable of causing disturbances to various surface structures. Inadequate consid-erations of the subsidence influences could result in poor public relation with local resi-dents and regulatory agencies, uneconomic operations, hazardous conditions, etc. A sys-tematic approach to assess and mitigate influences caused by Iongwall subsidence hadbeen developed and adopted to minimize the severity of these potential problems. Theapproach included accurate prediction of final and dynamic surface movements and de-formations, assessment of the severities and locations of the potential disturbances, anddesign and implementation of proper mitigation measures. The approach had been suc-cessfully applied at many Iongwall mining companies on numerous and various residential,farming, public and industrial structures. As a matter of fact, the state of Pennsylvania, thestate with largest number of Iongwall mines and highest Iongwall production in U.S., wouldlike to use such approach as the standards in dealing with Iongwall subsidence cases.

  11. Land subsidence due to groundwater withdrawal detected by InSAR time-series in Tazerbo well field, Libya

    Science.gov (United States)

    Tufekci, Nesrin; Schoups, Gerrit; Mahapatra, Pooja; van de Giesen, Nick; Hanssen, Ramon F.

    2014-05-01

    The Tazerbo well field is one of the well fields designed within the Great Man-Made River Project (GMMRP), which aims to deliver water to the eastern coast of Libya through an underground pipe network. It consists of 108 wells in three rows, where the wells are separated 1.3 km in longitude and 10 km in latitude. The planned total groundwater withdrawal from all wells is 1 million m3/day. The water is pumped from the deep sandstone aquifer (Nubian sandstone), which is overlaid by a thick mudstone-siltstone aquitard. Being heavily pumped, the aquifer and fine-grained sediments of the aquitard are expected to compact in time resulting in land subsidence. In order to investigate the surface deformation caused by groundwater pumping in the Tazerbo well field, Interferometric Synthetic Aperture Radar (InSAR) technique was utilized. InSAR is widely used for monitoring land subsidence and can provide sub-cm scale deformation information over large areas. Using the Persistent Scatterer method, SAR time series of 20 Envisat images, spanning from 2004 to 2010, are employed to analyze spatial and temporal distribution of land subsidence induced by groundwater withdrawal. The results are in a good agreement with simulated subsidence. In addition, the spatial distribution of InSAR observations seems to be promising in terms of detecting spatial heterogeneity of aquifer material.

  12. Monitoring ground subsidence due to underground mining using integrated space geodetic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Linlin Ge; Michael Hsing-Chung Chang; Chris Rizos [University of NSW, NSW (Australia)

    2004-04-01

    Differential radar interferometry (DInSAR) can deliver {approximately} 1cm height change resolution. The combination of regular radar beam scanning and movement of the satellites carrying the radar sensor enables imaging of the mining region in seconds, from which subtle ground movements can be detected. Quantitative validation comparing the DInSAR-derived subsidence profile against ground truth shows a best RMS error of 1.4cm. A methodology has been developed to use GPS (the Global Positioning System) observations to measure atmospheric disturbances so that the DInSAR results can be corrected. A Geographic Information System (GIS) has been used to post-process InSAR results throughout this project. GIS can be used to present the final results in various formats, for example, profiles for validating with ground truth, subsidence contour maps, and three-dimensional views. Professional looking thematic maps can be generated based on these analyses, lining up with the practice within the mining industry to deliver drawings/maps in a GIS format. Multi-temporal DInSAR results can be analysed using GIS, and the final results compiled into an animation, showing the subsidence region moving as time passes. A virtual reality image has been generated in the GIS, combining DEM, aerial photography, and DInSAR subsidence results. The UNSW InSAR-GPS-GIS Integration Software has been developed to support the seamless flow of data among the three technologies, DInSAR, GPS, and GIS. Several radar satellite missions, some especially designed for InSAR, are scheduled for launch in the near future. Therefore radar data of global coverage with weekly or even daily revisit will be made available at multiple radar bands. With atmospheric disturbances properly accounted for, DInSAR will be a cost-effective, reliable, and operational tool that complements traditional ground survey methods.

  13. Experimental Study on the Microstructure Evolution of Mixed Disposal Paste in Surface Subsidence Areas

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2016-05-01

    Full Text Available The integrated disposal of surface subsidence pits and surface solid waste can be realized by backfilling a surface subsidence area with a paste made from the solid wastes of mines, such as tailings and waste rock. The microstructures of these wastes determine the macroscopic properties of a paste backfill. This paper presents an experimental study on the internal structure evolution of pasty fluid mixed with different waste rock concentrations (10%, 30%, and 50% and cement dosages (1% and 2% under damage. To this end, a real-time computed tomography (CT scan is conducted using medical CT and a small loading device. Results show that UCS (uniaxial compressive strength increases when the amount of cement increases. Given a constant amount of cement, UCS increases first and then decreases as waste rock content increases. UCS is maximized at 551 kPa when the waste rock content is 30%. The paste body is a typical medium used to investigate initial damage, which mainly consists of microholes, pores, and microcracks. The initial damages also exhibit a high degree of random inhomogeneity. After loading, cracks are initiated and expand gradually from the original damage location until the overall damages are generated. The mesostructure evolution model of the paste body is divided into six categories, and this mesostructure is reasonable when the waste rock content is 30%.

  14. Dynamic subsidence prediction of ground surface above salt cavern gas storage considering the creep of rock salt

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A new model is proposed to predict the dynamic subsidence of ground surface above salt cavern gas storage during the leaching and storage, which takes into account the creep of rock salt. In the model, the extended form of Gaussian curve is adopted to figure out the shape of subsidence areas. The corresponding theoretical formulas are derived. In addition, parameters are studied to investigate the surface subsidence as a function of the salt ejection rate, internal pressure, buried depth, diameter, height, running time, etc. Through an example, the subsidence of the salt cavern gas storage located at Jiangsu of China obtained by the new model was compared with those by Peter A F formula, Schober & Sroka formula and FLAC3D through simulation. The results showed the proposed model is precise and correct, and can meet the actual engineering demands. The surface subsidence is equidirectional with the increase of salt ejection rate, depth, diameter, height, and running time, but reverse to the increase of internal pressure. The depth, diameter, running time and internal pressure have great effects on the subsidence, whereas the salt ejection rate and height have little influences on it.

  15. STRATA AND SURFACE SUBSIDENCE CONTROL IN STRIP-PARTIAL MINING UNDER BUILDINGS

    Institute of Scientific and Technical Information of China (English)

    吴立新; 王金庄; 赵学胜; 李邦三

    1994-01-01

    This paper systematically expounds the history and present situation of the research & application of strip-partial mining at home and abroad. The prospect of using strip-partial mining mcthod to mine under buildings (structures) at the present situation of market economy is also expounded here. Strata & surface subsldcnce mechanism of strip-partiai mining, the optimization of the width of unit goal & coal pillar as weal as the calculation method of surface subsidenoc pridiction based on Holding-Plate Control Theory and Coal Pillar Long-term Stability, which are our research achivements in recent years about strata & surface subsidence control in strip-partial mining, are the main points introduced here.

  16. Multi-scale modelling for the assessment of water quality and land subsidence due to salt layers dissolution

    Science.gov (United States)

    Gourdier, Sébastien; Bazargan-Sabet, Behrooz; Quang Vong, Chan

    2016-04-01

    Long term evolution of salt mine depends on mechanical behavior of the material but also on specific conditions like the intrusion of water into working areas. Such phenomenon has been observed in the Nancy Basin (East of France) where brine percolates through access shafts accompanied by significant subsidence at the surface level, bringing about growing societal concerns. In order to understand the mechanisms and kinetics of dissolution of salt inducing the phenom-enon of subsidence, a numerical model is implemented. The circulation of water between the salt layer and the impervious layer induces the creation of dissolution channels. In active disso-lution zones, the channel network constantly evolves: new channels appear with new dissolution zones while others collapse because of their too important dimensions. The model simulates the phenomenon of dissolution at the channel scale first, then at the basin scale. Dissolution channels modeling has been realized using COMSOL Multiphysics® with Darcy's Law and Solute Transport interfaces. At the channel scale, realistic parameters used as input data gave raise to output results con-sistent with the expected range of values for numerical assessment of the transient period and mass fluxes. At the basin scale, initial porosity and hydraulic conductivity fields, related to each other by a cubic law, are assumed to follow a Weibull distribution. From this initial state, the transient model calculates the evolution of porosity with time, taking into account Darcy's velocity as it was formulated by Yao et al. (2014). Progress in dissolution and transport gives rise to the creation of dissolution channels. Channels mechanical behavior is investigated through extending 2D model into 3D one. The calculations show that open channels collapse when they reach a width of approximatively one meter. The results of these investigations are consistent with the in situ measurements, notably with the estimation of the subsidence rate

  17. Geomechanical modeling of reservoir compaction, surface subsidence, and casing damage at the Belridge diatomite field

    Energy Technology Data Exchange (ETDEWEB)

    FREDRICH,JOANNE T.; DEITRICK,G.L.; ARGUELLO JR.,JOSE G.; DEROUFFIGNAC,E.P.

    2000-05-01

    Geologic, and historical well failure, production, and injection data were analyzed to guide development of three-dimensional geomechanical models of the Belridge diatomite field, California. The central premise of the numerical simulations is that spatial gradients in pore pressure induced by production and injection in a low permeability reservoir may perturb the local stresses and cause subsurface deformation sufficient to result in well failure. Time-dependent reservoir pressure fields that were calculated from three-dimensional black oil reservoir simulations were coupled uni-directionally to three-dimensional non-linear finite element geomechanical simulations. The reservoir models included nearly 100,000 gridblocks (100--200 wells), and covered nearly 20 years of production and injection. The geomechanical models were meshed from structure maps and contained more than 300,000 nodal points. Shear strain localization along weak bedding planes that causes casing dog-legs in the field was accommodated in the model by contact surfaces located immediately above the reservoir and at two locations in the overburden. The geomechanical simulations are validated by comparison of the predicted surface subsidence with field measurements, and by comparison of predicted deformation with observed casing damage. Additionally, simulations performed for two independently developed areas at South Belridge, Sections 33 and 29, corroborate their different well failure histories. The simulations suggest the three types of casing damage observed, and show that although water injection has mitigated surface subsidence, it can, under some circumstances, increase the lateral gradients in effective stress, that in turn can accelerate subsurface horizontal motions. Geomechanical simulation is an important reservoir management tool that can be used to identify optimal operating policies to mitigate casing damage for existing field developments, and applied to incorporate the effect of

  18. Increase in groundwater vulnerability due to land subsidence and earth fissures

    Science.gov (United States)

    Paredes, J.; Expósito, J. L.; Esteller, M. V.; Cervantes, M.; Mastachi-Loza, C. A.

    2013-05-01

    The vulnerability of an aquifer can be modified by structural phenomena such as cracks, which often occur in some aquifers linked to processes of intensive exploitation. These cracks may, under certain circumstances, permit the direct flow of pollutants into groundwater, even in areas of low vulnerability previously scheduled. Faced with this problem, this research aims to assess the vulnerability of the Toluca Valley aquifer, taking into account the cracks that have formed and include their characteristics as a factor that modifies some of the parameters for assessing the vulnerability. The vulnerability was determined using the method SINTACS, a GIS tool was used to develop appropriate mapping. In addition, fieldwork was carried out to characterize the existing cracks in the aquifer, which included infiltration rate tests. The characteristics of the cracking allowed defining changes in the scores of the parameters N (self-cleansing effect of the unsaturated zone) and T (soil type) so that these scores were increased after SINTACS map generated, in by doing so, we obtain a modified map SINTACS ,which considers cracking. In the final map we were able to see the vulnerability of the area where these cracks are located and changed from Medium to High-index; if one considers the entire surface of the aquifer, it can be seen in the map SINTACS, 23% of surface High-grade was moved to 26% on the map SINTACS modified. It should be noted that the increase in the area of high vulnerability corresponds to the urban sprawl of the city of Toluca, a factor that may affect the risk of contamination.

  19. Regional subsidence modelling in Murcia city (SE Spain using 1-D vertical finite element analysis and 2-D interpolation of ground surface displacements

    Directory of Open Access Journals (Sweden)

    S. Tessitore

    2015-11-01

    Full Text Available Subsidence is a hazard that may have natural or anthropogenic origin causing important economic losses. The area of Murcia city (SE Spain has been affected by subsidence due to groundwater overexploitation since the year 1992. The main observed historical piezometric level declines occurred in the periods 1982–1984, 1992–1995 and 2004–2008 and showed a close correlation with the temporal evolution of ground displacements. Since 2008, the pressure recovery in the aquifer has led to an uplift of the ground surface that has been detected by the extensometers. In the present work an elastic hydro-mechanical finite element code has been used to compute the subsidence time series for 24 geotechnical boreholes, prescribing the measured groundwater table evolution. The achieved results have been compared with the displacements estimated through an advanced DInSAR technique and measured by the extensometers. These spatio-temporal comparisons have showed that, in spite of the limited geomechanical data available, the model has turned out to satisfactorily reproduce the subsidence phenomenon affecting Murcia City. The model will allow the prediction of future induced deformations and the consequences of any piezometric level variation in the study area.

  20. Effect of the overconsolidation ratio of soils in surface settlements due to tunneling

    Institute of Scientific and Technical Information of China (English)

    Ludmila Strokova

    2013-01-01

    Construction of urban tunnels requires the control of surface subsidence to minimize any disturbance to nearby buildings and services. Past study of surface subsidence has been limited to mainly empirical solutions based on field studies, and very few analytical studies have been carried out. The available analytical solutions are not sufficient to include complex ground conditions;hence, a comprehensive analytical solution coupled with numerical modeling is necessary to model the effect of surface subsidence due to tunneling. This paper presents the results of modeling of surface settlements due to tunneling using the finite element method. The effect of the overconsolidation ratio of soils expressed in terms of the co-efficient of earth pressure at rest (K0) on surface subsidence due to tunneling is investigated. It is demonstrated that surface settlements appear to be sensitive to K0 values, and for geotechnical calculations pertaining to overconsolidated sand and clay soil, K0 values of 0.6 and 0.8, respectively, are proposed.

  1. Hydrogeology and simulation of groundwater flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system, Texas, 1891-2009

    Science.gov (United States)

    Kasmarek, Mark C.

    2012-01-01

    In cooperation with the Harris–Galveston Subsidence District, Fort Bend Subsidence District, and Lone Star Groundwater Conservation District, the U.S. Geological Survey developed and calibrated the Houston Area Groundwater Model (HAGM), which simulates groundwater flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system in Texas from predevelopment (before 1891) through 2009. Withdrawal of groundwater since development of the aquifer system has resulted in potentiometric surface (hydraulic head, or head) declines in the Gulf Coast aquifer system and land-surface subsidence (primarily in the Houston area) from depressurization and compaction of clay layers interbedded in the aquifer sediments.

  2. Subsidence in the holocene delta of The Netherlands

    NARCIS (Netherlands)

    Vonhögen, L.M.; Doornenbal, P.J.; Lange, G. de; Fokker, P.A.; Gunnink, J.L.

    2010-01-01

    The low-lying part of The Netherlands is very vulnerable in terms of surface subsidence due to peat oxidation and peat/clay compaction. To gain knowledge about this kind of subsidence and the factors driving it, a study was performed in which as many surface elevation data were collected as possible

  3. InSAR time-series analysis of land subsidence due to groundwater overexploitation in groundwater basins of central and northeast Iran

    Science.gov (United States)

    Sharifi, M.; Motagh, M.; Aipour, S.; Akbari, V.; Walter, T.; Rajabi, M.; Samadzadegan, F.; Djamour, Y.; Sedighi, M.

    2008-12-01

    We use Interferometric Synthetic Aperture (InSAR) observations acquired by the Envisat satellite during 2002-2008 to study land subsidence caused by groundwater over-exploitation in groundwater basins of central and northeast Iran. Earlier studies in these regions using a few interferograms showed rapid subsidence in the order of several centimetres per year. Here we use additional ENVISAT data and perform a time-series analysis using the small-baseline concept to better determine the temporal and spatial evolution of surface deformation.

  4. Surface subsidence induced by the Crandall Canyon Mine (Utah) collapse: InSAR observations and elasto-plastic modelling

    Science.gov (United States)

    Plattner, C.; Wdowinski, S.; Dixon, T. H.; Biggs, J.

    2010-12-01

    The Crandall Canyon Mine, Utah, collapse in 2007 August resulted in a total of nine fatalities. We processed data from the ALOS satellite acquired before and after the collapse to quantify surface subsidence associated with the collapse to better understand the collapse process. The deformation shows a steep V-shaped pattern of subsidence with slight asymmetry. We compare the fit of four different models that simulate the subsidence pattern. The first two models use elastic half-space rheology. We find that collapse alone cannot explain the observations, and a component of normal faulting is required to fit the data. The second set of models simulates collapse in elasto-plastic media. Only a small component of normal faulting is required in these models. We suggest that considering elasto-plastic material behaviour is particularly important for shallow deformation modelling, where microfractures and other non-elastic rheology are common. Disregarding this material behaviour can lead to biased model parameter estimates.

  5. Land subsidence in the Saga plane due to water shortage in 1994; Saga heiya ni okeru 1994 nen ijo kassui to jiban chinka

    Energy Technology Data Exchange (ETDEWEB)

    Hachiya, Y.; Kitajima, J. [Saga Prefectural Government Office, Saga (Japan); Jinno, K. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1996-08-21

    This paper reports land subsidence in Saga Plane during the abnormal drought in 1994. Saga Plane is arranged with a table land with a height of 20 m or lower above sea level, an alluvial fan, an inundation plane, and a delta in that order, with a reclaimed land spreading in front thereof. Groundwater is utilized mainly for industrial use in the Saga district, with consumption of 12 million m{sup 3} per year in around 1975 and 3.5 million m{sup 3} per year in recent years. The Shiraishi district uses groundwater mainly for tap water supply and agriculture, with normal consumption of 600 to 900 m{sup 3} per year having risen to 2000 m{sup 3} per year in 1994 when the abnormal drought has been experienced. The Saga prefectural government has been conducting groundwater collection amount survey, groundwater level measurement and level survey every year. As a result of observations, annual maximum subsidence has stopped at 3.3 cm and subsidence volume of 1280 m{sup 3} as a result of reduced groundwater collection in the Saga area. The Shiraishi area had ground water collection greatly increased due to drought, with the annual maximum subsidence having reached 16.0 cm and the subsidence volume of 5.9 million m{sup 3}. 7 refs., 11 figs., 2 tabs.

  6. Wave-planation surfaces in the East Sea back-arc basin: an indicator of back-arc subsidence history

    Science.gov (United States)

    Kim, G.; Yoon, S.; Kwon, Y.; Chough, S.

    2011-12-01

    This study focuses on delineating seismic characteristics and geomorphic features of wave-planation surfaces recognized in the southwestern East Sea, an extended back-arc area, based on the multi-channel seismic reflection data. The wave-planation surfaces are regarded to have originated from the co-occurrence of shallow-marine wave-induced abrasion on the bed rock and constructive sedimentation in forms of prograding clinoform and infilling of topographic depressions. The restricted shallow-marine wave-induced erosional and depositional processes are necessarily associated with regional-scale crustal subsidence caused by tectonic extension, thermal contraction, or sedimentary loading, in order to form such extensive and continuous wave-planation surfaces. The surfaces are classified into three types based on their present depths, possible initiation timings of subsidence, and the origins of underlain substrates, and each type of which reflects specific tectonic, volcanic, and sedimentary evolution histories. The WPS-1 occurs on the top of acoustic basement of rifted continental fragments in the SKP and continental margin terraces along the EKCM, which might have formed on the rifted continental crust undergoing subsequent thermal subsidence. The WPS-2 occurs on the top of flat-topped volcanic seamounts such as Kiminu Seamount (KS), Dok Is. (DI), Shimheungtaek Tablemount (ST), and Isabu Tablemount (IT), which most likely originated from initial subaerial volcanic eruption and following subsidence by loading effect of the volcanic edifices and minor thermal subsidence. The WPS-3 occurs on the top of the shelf-margin bank comprising the uplifted Tertiary sedimentary units. These surfaces might have originated from the subaerial exposure of existing syn-rift sedimentary units by tectonic inversion of the East Sea. In the Early Miocene (ca. 23 Ma) initial continental rifting occurred in subaerial environment, which resulted in rapid tectonic subsidence of SKP and EKCM

  7. Prediction of delayed subsidence

    Science.gov (United States)

    Burns, K.

    A predictive model of delayed subsidence is discussed. A numerical implementation is tested on one of the best-described study areas, Allegheny County in Pennsylvania. In planning insurance of restitution measures, a predictive model is of value in estimating the magnitude of the problem and the size of long-term budgetary commitments. Contrary to active subsidence, which occurs concurrently with mining operations, or is completed within a few days following coal extraction, delayed subsidence may take many years to appear at the surface after coal mines are abandoned. There are two principal morphological types of delayed subsidence: troughs, which are shallow depressions, and sinks, which are steep-sided crown pits. Both types are damaging to surface structures, and a variety of methods were introduced to deal with the problem, ranging from subsidence insurance to site restitution.

  8. Double trouble: subsidence and CO2 respiration due to 1,000 years of Dutch coastal peatlands cultivation

    Science.gov (United States)

    Erkens, Gilles; van der Meulen, Michiel J.; Middelkoop, Hans

    2016-05-01

    Coastal plains are amongst the most densely populated areas in the world. Many coastal peatlands are drained to create arable land. This is not without consequences; physical compaction of peat and its degradation by oxidation lead to subsidence, and oxidation also leads to emissions of carbon dioxide (CO2). This study complements existing studies by quantifying total land subsidence and associated CO2 respiration over the past millennium in the Dutch coastal peatlands, to gain insight into the consequences of cultivating coastal peatlands over longer timescales. Results show that the peat volume loss was 19.8 km3, which lowered the Dutch coastal plain by 1.9 m on average, bringing most of it below sea level. At least 66 % of the volume reduction is the result of drainage, and 34 % was caused by the excavation and subsequent combustion of peat. The associated CO2 respiration is equivalent to a global atmospheric CO2 concentration increase of ~0.39 ppmv. Cultivation of coastal peatlands can turn a carbon sink into a carbon source. If the path taken by the Dutch would be followed worldwide, there will be double trouble: globally significant carbon emissions and increased flood risk in a globally important human habitat. The effects would be larger than the historic ones because most of the cumulative Dutch subsidence and peat loss was accomplished with much less efficient techniques than those available now.

  9. Mechanisms, Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation (M3EF3): A UNESCO-IGCP project in partnership with the UNESCO-IHP Working Group on Land Subsidence

    Science.gov (United States)

    Teatini, P.; Carreon-Freyre, D.; Galloway, D. L.; Ye, S.

    2015-12-01

    Land subsidence due to groundwater extraction was recently mentioned as one of the most urgent threats to sustainable development in the latest UNESCO IHP-VIII (2014-2020) strategic plan. Although advances have been made in understanding, monitoring, and predicting subsidence, the influence of differential vertical compaction, horizontal displacements, and hydrostratigraphic and structural features in groundwater systems on localized near-surface ground ruptures is still poorly understood. The nature of ground failure may range from fissuring, i.e., formation of an open crack, to faulting, i.e., differential offset of the opposite sides of the failure plane. Ground ruptures associated with differential subsidence have been reported from many alluvial basins in semiarid and arid regions, e.g. China, India, Iran, Mexico, Saudi Arabia, Spain, and the United States. These ground ruptures strongly impact urban, industrial, and agricultural infrastructures, and affect socio-economic and cultural development. Leveraging previous collaborations, this year the UNESCO Working Group on Land Subsidence began the scientific cooperative project M3EF3 in collaboration with the UNESCO International Geosciences Programme (IGCP n.641; www.igcp641.org) to improve understanding of the processes involved in ground rupturing associated with the exploitation of subsurface fluids, and to facilitate the transfer of knowledge regarding sustainable groundwater management practices in vulnerable aquifer systems. The project is developing effective tools to help manage geologic risks associated with these types of hazards, and formulating recommendations pertaining to the sustainable use of subsurface fluid resources for urban and agricultural development in susceptible areas. The partnership between the UNESCO IHP and IGCP is ensuring that multiple scientific competencies required to optimally investigate earth fissuring and faulting caused by groundwater withdrawals are being employed.

  10. 3D numerical analyses for the quantitative risk assessment of subsidence and water flood due to the partial collapse of an abandoned gypsum mine.

    Science.gov (United States)

    Castellanza, R.; Orlandi, G. M.; di Prisco, C.; Frigerio, G.; Flessati, L.; Fernandez Merodo, J. A.; Agliardi, F.; Grisi, S.; Crosta, G. B.

    2015-09-01

    After the abandonment occurred in the '70s, the mining system (rooms and pillars) located in S. Lazzaro di Savena (BO, Italy), grown on three levels with the method rooms and pillars, has been progressively more and more affected by degradation processes due to water infiltration. The mine is located underneath a residential area causing significant concern to the local municipality. On the basis of in situ surveys, laboratory and in situ geomechanical tests, some critical scenarios were adopted in the analyses to simulate the progressive collapse of pillars and of roofs in the most critical sectors of the mine. A first set of numerical analyses using 3D geotechnical FEM codes were performed to predict the extension of the subsidence area and its interaction with buildings. Secondly 3D CFD analyses were used to evaluated the amount of water that could be eventually ejected outside the mine and eventually flooding the downstream village. The predicted extension of the subsidence area together with the predicted amount of the ejected water have been used to design possible remedial measurements.

  11. Experiences of the measurement of the extent of surface subsidence in the area of the Thorez Opencast mine

    Energy Technology Data Exchange (ETDEWEB)

    Erdelyi, L.

    1987-01-01

    Experiences gained in the course of subsidence measurement in the environs of the Thorez opencast mine (North Hungary) and the results of recent subsidence measurements are summarized. The direction, size, extension and temporal variation of surficial movements caused by draining of formation water are dealt with. Two cases are dealt with in detail which were not caused by surficial movements and the real causes were revealed just by the subsidence measurements.

  12. The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence

    Science.gov (United States)

    Barnett-Moore, Nicholas; Hassan, Rakib; Flament, Nicolas; Müller, Dietmar

    2017-02-01

    The present-day seismic structure of the mantle under the North Atlantic Ocean indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic domain during the Palaeocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, we use palaeogeographically constrained global mantle flow models to investigate the evolution of deep Earth flow beneath the North Atlantic since the Jurassic. The models show that over the last ˜ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. We extract model dynamic topography representative of a plume beneath the North Atlantic region since eruption at ˜ 60 Ma to present day and compare its evolution to available offshore geological and geophysical observations across the region. This comparison confirms that a widespread episode of Palaeocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ˜ 2500 km in diameter, arriving beneath central eastern Greenland during the Palaeocene. The location of the model plume eruption beneath eastern Greenland is compatible with several previous models. The predicted dynamic topography is within a few hundred metres of Palaeocene anomalous subsidence derived from well data. This is to be expected given the current limitations involved in modelling the evolution of Earth's mantle flow in 3-D, particularly its interactions with the base of a heterogeneous lithosphere as well as short-wavelength advective upper mantle flow, not captured in the presented global models.

  13. Model experimental research on deformation and subsidence characteristics of ground and wall rock due to mining under thick overlying terrane

    Energy Technology Data Exchange (ETDEWEB)

    Weizhong Ren; Chengmai Guo; Ziqiang Peng; Yonggang Wang [Chinese Academy of Sciences, Wuhan (China). Institute of Rock and Soil Mechanics

    2010-06-15

    Based on the prototype of a mine, a physical simulation test is conducted. The characteristics of the deformation and failure of the ground surface and the wall rock around a goaf, as well as the creep behavior of the wall rock deformation and the failure mechanism, are analyzed. The simulation test has greatly improved our understanding on the wall rock's deformation and failure characteristics. For the first time, digital close-range photogrammetry was used to measure the displacements in a sectional model test. The measurements by this technique agreed very well with those obtained by other methods, such as using dial gauges.

  14. Inverting subsidence data to detect possible compartmentalization in a gas reservoir in The Netherlands

    NARCIS (Netherlands)

    Visser, K.; Muntendam-Bos, A.G.; Kunakbayeva, G.; Leeuwenburgh, O.; Peters, E.; Fokker, P.A.

    2010-01-01

    Subsidence can be induced by hydrocarbon production, due to the decrease in pore pressure in the reservoir which causes the reservoir to compact. The subsidence at any point on the surface is a result of the compaction over a large area of the reservoir. The properties of the reservoir and thus the

  15. Inversion of surface subsidence data to quantify reservoir compartmentalization: A field study

    NARCIS (Netherlands)

    Fokker, P.A.; Visser, K.; Peters, E.; Kunakbayeva, G.; Muntendam-Bos, A.G.

    2010-01-01

    The Roswinkel gas field in the northeastern part of the Netherlands has been in production between 1980 and 2005. Located at about 2100 m depth, it is a severely faulted anticlinal structure, constituting up to 30 reservoir compartments. Due to the complicated nature of this field, there are large u

  16. Detecting and monitoring UCG subsidence with InSAR

    Energy Technology Data Exchange (ETDEWEB)

    Mellors, R J; Foxall, W; Yang, X

    2012-03-23

    The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidence related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool to image UCG related subsidence. Data from newer satellites and improved algorithms will improve effectiveness.

  17. Climatic change due to land surface alterations

    Energy Technology Data Exchange (ETDEWEB)

    Franchito, S.H.; Rao, V.B.

    1992-01-01

    A primitive equations global zonally averaged climate model is developed. The model includes biofeedback mechanisms. For the Northern Hemisphere the parameterization of biofeedback mechanisms is similar to that used by Gutman et al. For the Southern Hemisphere new parameterizations are derived. The model simulates reasonably well the mean annual zonally averaged climate and geobotanic zones. Deforestation, desertification, and irrigation experiments are performed. In the case of deforestation and desertification there is a reduction in the surface net radiation, evaporation, and precipitation and an increase in the surface temperature. In the case of irrigation experiment opposite changes occurred. In all the cases considered the changes in evapotranspiration overcome the effect of surface albedo modification. In all the experiments changes are smaller in the Southern Hemisphere.

  18. How to deal with subsidence in the Dutch delta?

    Science.gov (United States)

    Stouthamer, Esther; Erkens, Gilles

    2017-04-01

    In many deltas worldwide subsidence still is an underestimated problem, while the threat posed by land subsidence to low-lying urbanizing and urbanized deltas exceeds the threat of sea-level rise induced by climate change. Human-induced subsidence is driven by the extraction of hydrocarbons and groundwater, drainage of phreatic groundwater, and loading by buildings and infrastructure. The consequences of subsidence are increased flood risk and flood water depth, rising groundwater levels relative to the land surface, land loss, damage to buildings and infrastructure, and salinization of ground and surface water.. The Netherlands has a long history of subsidence. Large-scale drainage of the extensive peatlands in the western and northern parts of the Netherlands started approximately 1000 years ago as a result of rapid population growth. Subsidence is still ongoing due to (1) continuous drainage of the former peatland, which is now mainly in use as agricultural land and built-up area, (2) expansion of the built-up area and the infrastructural network, (3) salt mining and the extraction of gas in the northern Netherlands. Mitigating subsidence and its negative impacts requires understanding of the relative contribution of the drivers contributing to total subsidence, accurate predictions of land subsidence under different management scenarios, and its impacts. Such understanding enables the development of effective and sustainable management strategies. In the Netherlands, a lot of effort is put into water management aiming at amongst others the protection against floods and the ensuring agricultural activities, but a specific policy focusing on subsidence is lacking. The development of strategies to cope with subsidence is very challenging, because (1) the exact contribution of different drivers of subsidence to total subsidence is spatially different within the Netherlands, (2) there is no single problem owner, which makes it difficult to recognize this a common

  19. Insulator Surface Flashover Due to UV Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Javedani, J B; Houck, T L; Lahowe, D A; Vogtlin, G E; Goerz, D A

    2009-07-27

    The surface of an insulator under vacuum and under electrical charge will flashover when illuminated by a critical dose of ultra-violet (UV) radiation - depending on the insulator size and material, insulator cone angle, the applied voltage and insulator shot-history. A testbed comprised of an excimer laser (KrF, 248 nm, {approx}16 MW, 30 ns FWHM,), a vacuum chamber, and a negative polarity dc high voltage power supply ({le} -60 kV) were assembled to test 1.0 cm thick angled insulators for surface-flashover. Several candidate insulator materials, e.g. High Density Polyethylene (HDPE), Rexolite{reg_sign} 1400, Macor{trademark} and Mycalex, of varying cone angles were tested against UV illumination. Commercial energy meters were used to measure the UV fluence of the pulsed laser beam. In-house designed and fabricated capacitive probes (D-dots, >12 GHz bandwidth) were embedded in the anode electrode underneath the insulator to determine the time of UV arrival and time of flashover. Of the tested insulators, the +45 degree Rexolite insulator showed more resistance to UV for surface flashover; at UV fluence level of less than 13 mJ/cm{sup 2}, it was not possible to induce a flashover for up to -60 kV of DC potential across the insulator's surface. The probes also permitted the electrical charge on the insulator before and after flashover to be inferred. Photon to electron conversion efficiency for the surface of Rexolite insulator was determined from charge-balance equation. In order to understand the physical mechanism leading to flashover, we further experimented with the +45 degree Rexolite insulator by masking portions of the UV beam to illuminate only a section of the insulator surface; (1) the half nearest the cathode and subsequently, (2) the half nearest the anode. The critical UV fluence and time to flashover were measured and the results in each case were then compared with the base case of full-beam illumination. It was discovered that the time for the

  20. Stem surface roughness alters creep induced subsidence and 'taper-lock' in a cemented femoral hip prosthesis.

    Science.gov (United States)

    Norman, T L; Thyagarajan, G; Saligrama, V C; Gruen, T A; Blaha, J D

    2001-10-01

    The clinical success of polished tapered stems has been widely reported in numerous long term studies. The mechanical environment that exists for polished tapered stems, however, is not fully understood. In this investigation, a collarless, tapered femoral total hip stem with an unsupported distal tip was evaluated using a 'physiological' three-dimensional (3D) finite element analysis. It was hypothesized that stem-cement interface friction, which alters the magnitude and orientation of the cement mantle stress, would subsequently influence stem 'taper-lock' and viscoelastic relaxation of bone cement stresses. The hypothesis that creep-induced subsidence would result in increases to stem-cement normal (radial) interface stresses was also examined. Utilizing a viscoelastic material model for the bone cement in the analysis, three different stem-cement interface conditions were considered: debonded stem with zero friction coefficient (mu=0) (frictionless), debonded stem with stem-cement interface friction (mu=0.22) ('smooth' or polished) and a completely bonded stem ('rough'). Stem roughness had a profound influence on cement mantle stress, stem subsidence and cement mantle stress relaxation over the 24-h test period. The frictionless and smooth tapered stems generated compressive normal stress at the stem-cement interface creating a mechanical environment indicative of 'taper-lock'. The normal stress increased with decreasing stem-cement interface friction but decreased proximally with time and stem subsidence. Stem subsidence also increased with decreasing stem-cement interface friction. We conclude that polished stems have a greater potential to develop 'taper-lock' fixation than do rough stems. However, subsidence is not an important determinant of the maintenance of 'taper-lock'. Rather subsidence is a function of stem-cement interface friction and bone cement creep.

  1. Deriving Spatio-Temporal Development of Ground Subsidence Due to Subway Construction and Operation in Delta Regions with PS-InSAR Data: A Case Study in Guangzhou, China

    Directory of Open Access Journals (Sweden)

    Huiqiang Wang

    2017-09-01

    Full Text Available Subways have been an important method for relieving traffic pressures in urban areas, but ground subsidence, during construction and operation, can be a serious problem as it may affect the safety of its operation and that of the surrounding buildings. Thus, conducting long-term ground deformation monitoring and modeling for subway networks are essential. Compared with traditional geodetic methods, the Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR technique offers wider coverage and denser measurements along subway lines. In this study, we mapped the surface deformation of the Guangzhou subway network with Advanced Synthetic Aperture Radar (ASAR and Phased Array Type L-band Synthetic Aperture Radar (PALSAR data using the Interferometric Point Target Analysis (IPTA technique. The results indicate that newly excavated tunnels have regional subsidence with an average rate of more than 8 mm/year, as found on Lines Two, Three, Six, and GuangFo (GF. Furthermore, we determined the spatio-temporal subsidence behavior of subways with PALSAR in delta areas using Peck’s formula and the logistic time model. We estimated the tunneling-related parameters in soft soil areas, which had not been previously explored. We examined a section of line GF, as an example, to estimate the ground settlement trough development. The results showed the maximum settlement increased from −5.2 mm to −23.6 mm and its ground loss ratio ranged from 1.5–8.7% between 13 July 2008 and 19 January 2011. In addition, we found that the tunnels in line GF will become stable after a period of about 2300 days in peak subsidence areas. The results show that the proposed approach can help explain the dynamic ground subsidence along a metro line. This study can provide references for urban subway projects in delta areas, and for the risk assessment of nearby buildings and underground pipelines along metro lines.

  2. Using radar interferometry and SBAS technique to detect surface subsidence relating to coal mining in Upper Silesia from 1993-2000 and 2003-2010

    Directory of Open Access Journals (Sweden)

    Nádudvari Ádám

    2016-03-01

    Full Text Available In the presented research ERS1-2 and Envisat ASAR archive data were used for the periods 1993 – 2000 and 2003 – 2010. The radar images were acquired over Upper Silesia in southern Poland. DinSAR (Differential InSAR and SBAS (Small Baseline Subset methods were applied for the detection of the most subsided areas. The DinSAR images were layer stacked for an image using 26 interferometry pairs of ERS1-2 SAR and 16 pairs from Envisat ASAR images in an ascending-descending orbit combination. The stacking of these images showed the most subsided parts of these cities even under low coherent areas, but the results are less precise. In the Upper Silesian Coal Basin, intensive underground coal exploitation has resulted in several surface deformations under Bytom (~8-17 km2, Piekary Śląskie (~9-15 km2, Ruda Śląska (~32-42 km2 and Katowice (~20-23 km2 with 25-40 cm of subsidence (in general in the studied time periods. The SBAS technique has also shown that coal mining caused subsidence in the cities of Bytom, Katowice, and Piekary Śląskie of 5-7 cm/yr. The presented SBAS method did not work for low coherent areas, e.g. dense forested areas. DInSAR data also pointed to several decreasingly less active mining areas, which relate to the mine closures in Bytom and Ruda Śląska, which is also verified by the time series analysis.

  3. Measurements of the Balance of Subsidence and Sedimentation in the Coastal Zone of Bangladesh

    Science.gov (United States)

    Steckler, M. S.; Mondal, D. R.; Akhter, S. H.; Davis, J. L.; Goodbred, S. L., Jr.; Wilson, C.; Bulbul, M. A.

    2015-12-01

    In the face of rising sea levels, the balance of land subsidence, sea level rise and sedimentation is critical for low-lying deltaic regions. Deltas commonly experience subsidence due to compaction of their thick sediment accumulations and other processes. Many are susceptible to growth faulting and seaward collapse of the sediment pile on detachment layers (salt and/or shales) leading to even greater subsidence. We present evidence for moderate subsidence rates and continuing active sedimentation at the Ganges-Brahmaputra Delta in Bangladesh. Subsidence rates are based on continuous GPS, including three new coastal stations established in 2012, hourly tide gauge data for 1977-2012 at 16 sites, two historical sites with ages of 300 years (salt-making kilns) and 400 years (Hindu temple), and sedimentation accumulation rates of near-sea-level deposits from hand-drilled tube wells. Results so far suggest that most sites are subsiding at 3-4 mm/y, although some higher rates are recorded. Updated estimates for subsidence will be presented. Two sets of vertical optical strainmeters record sediment compaction and inform its variation with depth. Sedimentation estimates based on sedimentation plots, marker horizons, and surface elevation tables (SETs) suggest that accumulation rates in natural areas near the coast currently compensate for relative subsidence, whereas human-modified areas farther inland receive insufficient sediment and are at risk. We hypothesize that the moderate subsidence rate of the delta is due to buttressing of the margin by the continental rise. The slope-rise break is shallow at 1 km water depth due to the high sediment supply feeding the Bengal Fan. Thus the thick wedge of continental rise sediments rise higher than the top of the weak overpressured sediments in the delta that could act as a décollement surface. This prevents the seaward collapse of the delta and associated higher rates of subsidence.

  4. Review: Advances in delta-subsidence research using satellite methods

    Science.gov (United States)

    Higgins, Stephanie A.

    2016-05-01

    Most of the world's major river deltas are sinking relative to local sea level. The effects of subsidence can include aquifer salinization, infrastructure damage, increased vulnerability to flooding and storm surges, and permanent inundation of low-lying land. Consequently, determining the relative importance of natural vs. anthropogenic pressures in driving delta subsidence is a topic of ongoing research. This article presents a review of knowledge with respect to delta surface-elevation loss. The field is rapidly advancing due to applications of space-based techniques: InSAR (interferometric synthetic aperture radar), GPS (global positioning system), and satellite ocean altimetry. These techniques have shed new light on a variety of subsidence processes, including tectonics, isostatic adjustment, and the spatial and temporal variability of sediment compaction. They also confirm that subsidence associated with fluid extraction can outpace sea-level rise by up to two orders of magnitude, resulting in effective sea-level rise that is one-hundred times faster than the global average rate. In coming years, space-based and airborne instruments will be critical in providing near-real-time monitoring to facilitate management decisions in sinking deltas. However, ground-based observations continue to be necessary for generating complete measurements of surface-elevation change. Numerical modeling should seek to simulate couplings between subsidence processes for greater predictive power.

  5. Subsidence Serves as an Indicator of Groundwater Arsenic Risk in the San Joaquin Valley, California

    Science.gov (United States)

    Smith, R.; Knight, R. J.; Fendorf, S. E.

    2016-12-01

    Groundwater arsenic concentrations dominantly result from anaerobic conditions. Within aquifers, clays are typically the major hosts of solid-phase arsenic, and clay layers often have restricted oxygen supply, resulting in anaerobic conditions and the concomitant relase of arsenic to groundwater. But it is not until water is drawn from the clay layers, through over-pumping of aquifers, that arsenic enters the water supply. Due to the mechanical properties of clays, the volume of groundwater withdrawn is effectively approximated by their vertical deformation, the sum of which is expressed at the surface as subsidence. As a result, subsidence can serve as an indicator, or "early warning system", of the presence of arsenic in the pumped groundwater. In the San Joaquin Valley of California, there has been significant subsidence due to groundwater extraction from clays for nearly a century. Historical subsidence in this area has been measured with leveling surveys, GPS and extensometers, and has been reproduced in groundwater models. More recent subsidence can be measured directly using Interferometric Synthetic Aperture Radar (InSAR). We use recent (post-2007) arsenic level data from the southern portion of the San Joaquin Valley to train a random forest model. Predictors in the model include historical (pre-2002) estimates of subsidence, more recent (2007-2011) InSAR estimates of subsidence, and other predictors representing additional mechanisms that could affect arsenic levels in groundwater, such as groundwater flow, redox potential and position in the basin. We find that recent subsidence is a strong predictor of arsenic levels; historical subsidence could have some impact but is less significant. These results indicate that avoiding over-pumping of the aquifer may improve water quality over a time period on the order of 10 years. Incorporating subsidence into arsenic prediction maps can improve our ability to identify and manage areas that have a higher risk of

  6. InSAR derived horizontal subsidence gradient as a tool for hazard assessment in urban areas.

    Science.gov (United States)

    Cabral-Cano, E.; Dixon, T.; Diaz-Molina, O.

    2007-05-01

    Mexico City's subsidence has been recognized for over a century, after the first well battery was drilled to supply water to the rapidly growing city at the end of the XIX century. Consequences of the subsidence process are costly but the economic consequences of subsidence in urban areas is hard to assess due to the fact that their costs are generally factored into yearly maintenance budgets rather than accounting for them as a unique natural disaster. It has thus become increasingly important to assess the extent and magnitude of damage due to ground subsidence in the Mexico City metropolitan area. Periodic InSAR and GPS measurements including data from an 8 site permanent GPS network in Mexico City has enabled us to derive an integrated composite displacement map for Mexico City. This image was used to calculate the horizontal subsidence gradient for areas smaller than 100x100m throughout the city by computing the observed displacement difference divided by the respective pixel to pixel horizontal distance and comparing similarly calculated values from all adjacent pixels in order to select the maximum gradient. Both empiric and analytical approaches can been used to correlate the potential for surface faulting in high horizontal subsidence gradient zones and show that the principal factor for constraining these areas can be successfully determined using a combined Differential InSAR and GPS approach. We present surface faulting risk maps for several cities in central Mexico derived from the horizontal subsidence gradient approach as an example of this technique.

  7. Traces of warping subsided tectonic blocks on Miranda, Enceladus, Titan

    Science.gov (United States)

    Kochemasov, G.

    2007-08-01

    Icy satellites of the outer Solar system have very large range of sizes - from kilometers to thousands of kilometers. Bodies less than 400-500 km across have normally irregular shapes , often presenting simple Plato's polyhedrons woven by standing inertiagravity waves (see an accompanying abstract of Kochemasov). Larger bodies with enhanced gravity normally are rounded off and have globular shapes but far from ideal spheres. This is due to warping action of inertia-gravity waves of various wavelengths origin of which is related to body movements in elliptical keplerian orbits with periodically changing accelerations (alternating accelerations cause periodically changing forces acting upon a body what means oscillations of its spheres in form of standing warping waves). The fundamental wave 1 and its first overtone wave 2 produce ubiquitous tectonic dichotomy - two segmental structure and tectonic sectoring superimposed on this dichotomy. Two kinds of tectonic blocks (segments and sectors) are formed: uplifted (+) and subsided (-). Uplifting means increasing planetary radius of blocks, subsiding - decreasing radius (as a sequence subsiding blocks diminishing their surfaces must be warped, folded, wrinkled; uplifting blocks increasing their surfaces tend to be deeply cracked, fallen apart). To level changing angular momenta of blocks subsided areas are filled with denser material than uplifted ones (one of the best examples is Earth with its oceanic basins filled with dense basalts and uplifted continents built of less dense on average andesitic material). Icy satellites follow the same rule. Their warped surfaces show differing chemistries or structures of constructive materials. Uplifted blocks are normally built with light (by color and density) water ice. Subsided blocks - depressions, "seas', "lakes", coronas - by somewhat denser material differing in color from water ice (very sharply - Iapetus, moderately - Europa, slightly - many saturnian satellites). A very

  8. D-InSAR技术地表沉降监测概述%The Principle of D-InSAR Technology Used in the Monitoring of Surface Subsidence

    Institute of Scientific and Technical Information of China (English)

    周荣; 顾爱辉; 钱小娟

    2012-01-01

      传统的地表沉降监测技术,如全球定位系统、精密水准测量和土工测量等,存在空间分辨率低、监测范围小和费用高的局限性。本文介绍了近几年迅速发展的监测地表沉降的合成孔径雷达差分干涉测量(D-InSAR)技术,主要对合成孔径雷达干涉测量(InSAR)技术的原理、D-InSAR 技术的原理和处理流程做了详细的阐述,并对 D-InSAR 技术中的不足作了说明。%  Traditional surface subsidence monitoring technologies, for example, Global Positioning System, Precise Leveling and Geotechnical Measurements, have the limitation of low spatial resolution, small coverage and high cost. D-InSAR, which was developed in recent years, is introduced to monitor the surface subsidence in this paper. The principle of InSAR and process of D-InSAR were described in detail. Moreover, the deficiencies of D-InSAR were described too.

  9. Spatial Analysis of Soil Subsidence in Peat Meadow Areas in Friesland in Relation to Land and Water Management, Climate Change, and Adaptation

    NARCIS (Netherlands)

    Brouns, Karlijn; Eikelboom, Tessa; Jansen, Peter C; Janssen, Ron; Kwakernaak, Cees; van den Akker, Jan J H; Verhoeven, Jos T A

    2015-01-01

    Dutch peatlands have been subsiding due to peat decomposition, shrinkage and compression, since their reclamation in the 11th century. Currently, subsidence amounts to 1-2 cm/year. Water management in these areas is complex and costly, greenhouse gases are being emitted, and surface water quality is

  10. Threat of land subsidence in and around Kolkata City and East Kolkata Wetlands, West Bengal, India

    Indian Academy of Sciences (India)

    P Sahu; P K Sikdar

    2011-06-01

    This paper attempts to estimate the possible rate of land subsidence of Kolkata City including Salt Lake City and the adjoining East Kolkata Wetlands located at the lower part of the deltaic alluvial plain of South Bengal basin. Demand of groundwater for drinking, agricultural and industrial purposes has increased due to rapid urbanization. The subsurface geology consists of Quaternary sediments comprising a succession of clay, silty clay and sand of various grades. Groundwater occurs mostly under confined condition except in those places where the top aquitard has been obliterated due to the scouring action of past channels. Currently, the piezometric head shows a falling trend and it may be accelerated due to further over-withdrawal of groundwater resulting in land subsidence. The estimated mean land subsidence rate is 13.53 mm/year and for 1 m drop in the piezometric head, the mean subsidence is 3.28 cm. The surface expression of the estimated land subsidence is however, cryptic because of a time lag between the settlement of the thick low-permeable aquitard at the top and its surface expression. Therefore, groundwater of the cities and wetland areas should be developed cautiously based on the groundwater potential to minimize the threat of land subsidence.

  11. Development mechanism of cavity damage under urban roads and its influence on road surface subsidence%城市道路地下空洞病害发展机理及对路面塌陷的影响

    Institute of Scientific and Technical Information of China (English)

    陶连金; 袁松; 安军海

    2015-01-01

    外界因素作用易引起城市道路地下空洞破坏,甚至向上发展至地面形成地层塌陷。基于离散元软件对城市道路路基下空洞的发展破坏进行数值模拟,分析空洞规模、埋深、施工振动、空洞周围土性对空洞稳定性的影响。结果表明:道路路面沉降随着空洞埋深的减小和尺寸的增大,均出现先急剧增加后趋于平缓的过程。该曲线的拐点为道路安全性预测的关键点。当空洞与扰动土层相距3 m以内时,必须考虑施工扰动的影响。沉降值随空洞所在土层的黏聚力和摩擦角均近似呈线性变化。该研究从颗粒细观角度揭示了地下空洞发展至路面塌陷的破坏机制,为地下病害研究提供了新方法。%This paper is concerned specifically with a deeper study addressing cavity disease—cavity damage more likely to occur under urban roads due to the external factors and even cause road surface subsidence. The study involves simulating the development and damage of cavity under urban road using distinct element software and analyzing the impact of the cavity size, buried depth, the vibration during construction, the property of soil around the cavity on the stability of the cavity. The study demonstrates that, as a result of the decrease of the cavity depth and the increase of size, the road surface is subjected to the typical subsidence tending to sharply increase, followed by a flat increase, suggesting that the point of inflexion holds the key to the road safety prediction; the occurrence of a 3-m-distance between cavity and disturbed soil necessitates the consideration of the influence of vibration during construction;and sur-face has subsidence value approximate to linear variation due to the cohesive force and the friction angle of soil to which the cavity is exposed. The study offers a new insight into failure mechanism behind the underground cavity and the resulting road surface subsidence thanks to

  12. Volcanic subsidence triggered by the 2011 Tohoku earthquake in Japan: Hot and weak material hypothesis

    Science.gov (United States)

    Takada, Youichiro; Fukushima, Yo

    2014-05-01

    With spaceborne interferometric synthetic aperture radar (InSAR) analysis, we found that the 2011 Mw 9.0 Tohoku earthquake in Japan (March 11, 2011) has triggered unprecedented subsidence of multiple volcanoes. Similar phenomenon has been reported for the 2010 Mw 8.8 Maule earthquake (Pritchard et al., 2013). We used SAR data acquired before and after the mainshock by ALOS (PALSAR). By removing long wave-length phase trend from InSAR images, we obtained the localized subsidence signals at five active volcanoes: Mt. Akitakoma, Mt. Kurikoma, Mt. Zao, Mt. Azuma, and Mt. Nasu. All of them belong to the volcanic front of Northeast Japan. The subsidence areas exhibit elliptic shape elongated in the North-South direction - perpendicular to the principal axis of the extensional stress change due to the Tohoku earthquake. Major axis of the ellipse reaches 15 - 20 km, and the amount of subsidence is up to 15 cm (Mt. Azuma). GPS data from two volcanoes also indicate surface subsidence consistent with the satellite radar observations. Furthermore, the GPS data show that the subsidence occurred immediately after the earthquake. A common feature of the five volcanoes is their high geothermal activity. The areas of high geothermal gradient and high thermal water temperature are in good agreement with the area of subsidence detected by InSAR. Also, the Late Cenozoic calderas cluster around the subsidence regions, which implies that hot plutonic bodies once intruded are still hot and highly deformable even now. According to numerical modelling, the observed subsidence can be explained by the co-seismic response of fluid-filled ellipsoid beneath each volcano. We confirmed that the surface subsidence is also caused by the ellipsoid filled with elastic body of low shear strength. We further checked that an ellipsoid is more effective to cause the subsidence than a sphere when the ellipsoid is elongated perpendicular to the tension axis of the imposed stress. References: Takada, Y. and

  13. AN ESTIMATION OF FUZZY RELIABILITY OF DISTINCT ELEMENT METHOD IN PREDICTION OF SURFACE SUBSIDENCE DUE TO COAL MINING

    Institute of Scientific and Technical Information of China (English)

    张玉卓

    1998-01-01

    The quantitative evaluation of errors involved in a particular numerical modelling is of prime importance for the effectiveness and reliability of the method. Errors in Distinct Element Modelling are generated mainly through three resources as simplification of physical model, determination of parameters and boundary conditions. A measure of errors which represent the degree of numerical solution 'close to true value' is proposed through fuzzy probability in this paper. The main objective of this paper is to estimate the reliability of Distinct Element Method in rock engineering practice by varying the parameters and boundary conditions. The accumulation laws of standard errors induced by improper determination of parameters and boundary conditions are discussed in delails. Furthermore, numerical experiments are given to illustrate the estimation of fuzzy reliability. Example shows that fuzzy reliability falls between 75%-98% when the relative standard errors of input data is under 10 %.

  14. Adhesion between silica surfaces due to hydrogen bonding

    Science.gov (United States)

    Bowen, James; Rossetto, Hebert L.; Kendall, Kevin

    2016-09-01

    The adhesion between surfaces can be enhanced significantly by the presence of hydrogen bonding. Confined water at the nanoscale can display behaviour remarkably different to bulk water due to the formation of hydrogen bonds between two surfaces. In this work we investigate the role of confined water on the interaction between hydrophilic surfaces, specifically the effect of organic contaminants in the aqueous phase, by measuring the peak adhesive force and the work of adhesion. Atomic force microscope cantilevers presenting hemispherical silica tips were interacted with planar single crystals of silica in the presence of dimethylformamide, ethanol, and formamide; solution compositions in the range 0-100 mol% water were investigated for each molecule. Each molecule was chosen for its ability to hydrogen bond with water molecules, with increasing concentrations likely to disrupt the structure of surface-bound water layers. With the exception of aqueous solutions containing low concentrations of ethanol, all molecules decreased the ability of confined water to enhance the adhesion between the silica surfaces in excess of the predicted theoretical adhesion due to van der Waals forces. The conclusion was that adhesion depends strongly on the formation of a hydrogen-bonding network within the water layers confined between the silica surfaces.

  15. Land Subsidence International Symposium held in Venice

    Science.gov (United States)

    The Third International Symposium on Land Subsidence was held March 18-25, 1984, in Venice, Italy. Sponsors were the Ground-Water Commission of the International Association of Hydrological Sciences (IAHS), the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the Italian National Research Council (CNR), the Italian Regions of Veneto and Emilia-Romagna, the Italian Municipalities of Venice, Ravenna, and Modena, the Venice Province, and the European Research Office. Cosponsors included the International Association of Hydrogeologists (IAH), the International Society for Soil Mechanics and Foundation Engineering (ISSMFE), and the Association of Geoscientists for International Development (AGID).Organized within the framework of UNESCO's International Hydrological Program, the symposium brought together over 200 international interdisciplinary specialists in the problems of land subsidence due to fluid and mineral withdrawal. Because man's continuing heavy development of groundwater, gas, oil, and minerals is changing the natural regime and thus causing more and more subsiding areas in the world, there had been sufficient new land subsidence occurrence, problems, research, and remedial measures since the 1976 Second International Symposium held in Anaheim, California, to develop a most interesting program of nearly 100 papers from about 30 countries. The program consisted of papers covering case histories of fluid and mineral withdrawal, engineering theory and analysis, karst “sink-hole”-type subsidence, subsidence due to dewatering of organic deposits or due to application of water (hydrocompaction), instrumentation, legal, socioeconomic, and environmental effects of land subsidence, and remedial works.

  16. The help of Advanced Satellite Interferometry in assessing the effect of human-induced surface deformation in naturally subsiding areas. Methodological approach and applications

    Science.gov (United States)

    Tamburini, Andrea; Giannico, Chiara; Del Conte, Sara; Teatini, Pietro

    2014-05-01

    Underground water extraction, natural gas storage either in depleted hydrocarbon reservoirs or in aquifers, and excavations for civil works (e.g. underground passageways, car parks, etc.) in flat areas are responsible for surface deformation that can damage pre-existing structures and modify drainage pathways. Deformation patterns associated to different underground show in many cases typical patterns. Their recognition can help in disentangling different processes when occurring in areas already affected by natural subsidence, such as coastal areas and inner sedimentary plains. Moreover, assessing the extent of human-induced deformation can help in identifying causes, modelling phenomena, predicting their evolution and adopting proper remedial measures. Advanced Satellite Interferometry provides a synoptic view of surface displacements over large areas and long time-spans and has become a standard in several Italian regions where underground fluid injection and withdrawal is going on. The integration of interferometric measurements with ground (leveling, GPS) and underground (borehole extensometers, piezometers, micro-seismic) monitoring networks can provide an exhaustive framework of the effect induced at surface level by underground human activities at local and regional scale. Documented case studies demonstrating the effectiveness of the above approach will be presented.

  17. Integration of InSAR and GIS in the Study of Surface Faults Caused by Subsidence-Creep-Fault Processes in Celaya, Guanajuato, Mexico

    Science.gov (United States)

    Avila-Olivera, Jorge A.; Farina, Paolo; Garduño-Monroy, Victor H.

    2008-05-01

    In Celaya city, Subsidence-Creep-Fault Processes (SCFP) began to become visible at the beginning of the 1980s with the sprouting of the crackings that gave rise to the surface faults "Oriente" and "Poniente". At the present time, the city is being affected by five surface faults that display a preferential NNW-SSE direction, parallel to the regional faulting system "Taxco-San Miguel de Allende". In order to study the SCFP in the city, the first step was to obtain a map of surface faults, by integrating in a GIS field survey and an urban city plan. The following step was to create a map of the current phreatic level decline in city with the information of deep wells and using the "kriging" method in order to obtain a continuous surface. Finally the interferograms maps resulted of an InSAR analysis of 9 SAR images covering the time interval between July 12 of 2003 and May 27 of 2006 were integrated to a GIS. All the maps generated, show how the surface faults divide the city from North to South, in two zones that behave in a different way. The difference of the phreatic level decline between these two zones is 60 m; and the InSAR study revealed that the Western zone practically remains stable, while sinkings between the surface faults "Oriente" and "Universidad Pedagógica" are present, as well as in portions NE and SE of the city, all of these sinkings between 7 and 10 cm/year.

  18. Investigation of differential surface removal due to electropolishing at JLab

    Energy Technology Data Exchange (ETDEWEB)

    Marhauser, Frank [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Folkie, James [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Reece, Charles [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal, however, is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.

  19. Measurement of Subsidence in the Yangbajain Geothermal Fields from TerraSAR-X

    Science.gov (United States)

    Li, Yongsheng; Zhang, Jingfa; Li, Zhenhong

    2016-08-01

    Yangbajain contains the largest geothermal energy power station in China. Geothermal explorations in Yangbajain first started in 1976, and two plants were subsequently built in 1981 and 1986. A large amount of geothermal fluids have been extracted since then, leading to considerable surface subsidence around the geothermal fields. In this paper, InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images. Due to its high resolution and short repeat cycle, TerraSAR-X provides detailed surface deformation information at the Yangbajain geothermal fields.

  20. Satellite signal shows storage-unloading subsidence in North China

    Science.gov (United States)

    Moiwo, J. P.; Tao, F.

    2015-06-01

    Worsening water storage depletion (WSD) contributes to environmental degradation, land subsidence and earthquake and could disrupt food production/security and social stability. There is need for efficient water use strategies in North China, a pivotal agrarian, industrial and political base in China with a widespread WSD. This study integrates satellite, model and field data products to investigate WSD and land subsidence in North China. In the first step, GRACE (Gravity Recovery and Climate Experiment) mass rates are used to show WSD in the region. Next, GRACE total water storage (TWS) is corrected for soil water storage (SWS) to derive groundwater storage (GWS) using GLDAS (Global Land Data Assimilation System) data products. The derived GWS is compared with GWS obtained from field-measured groundwater level to show land subsidence in the study area. Then GPS (Global Positioning System) data of relative land surface change (LSC) are used to confirm the subsidence due to WSD. A total of ~ 96 near-consecutive months (January 2002 through December 2009) of datasets are used in the study. Based on GRACE mass rates, TWS depletion is 23.76 ± 1.74 mm yr-1 or 13.73 ± 1.01 km3 yr-1 in the 578 000 km2 study area. This is ~ 31 % of the slated 45 km3 yr-1 water delivery in 2050 via the South-North Water Diversion Project. Analysis of relative LSC shows subsidence of 7.29 ± 0.35 mm yr-1 in Beijing and 2.74 ± 0.16 mm yr-1 in North China. About 11.53 % (2.74 ± 0.18 mm or 1.58 ± 0.12 km3) of the TWS and 8.37 % (1.52 ± 0.70 mm or 0.88 ± 0.03 km3) of the GWS are attributed to storage reductions accompanying subsidence in the region. Although interpretations of the findings require caution due to the short temporal and large spatial coverage, the concurrence of WSD and land subsidence could have adverse implications for the study area. It is critical that the relevant stakeholders embark on resource-efficient measures to ensure water availability, food security, ecological

  1. Boussinesq modeling of surface waves due to underwater landslides

    Directory of Open Access Journals (Sweden)

    D. Dutykh

    2013-05-01

    Full Text Available Consideration is given to the influence of an underwater landslide on waves at the surface of a shallow body of fluid. The equations of motion that govern the evolution of the barycenter of the landslide mass include various dissipative effects due to bottom friction, internal energy dissipation, and viscous drag. The surface waves are studied in the Boussinesq scaling, with time-dependent bathymetry. A numerical model for the Boussinesq equations is introduced that is able to handle time-dependent bottom topography, and the equations of motion for the landslide and surface waves are solved simultaneously. The numerical solver for the Boussinesq equations can also be restricted to implement a shallow-water solver, and the shallow-water and Boussinesq configurations are compared. A particular bathymetry is chosen to illustrate the general method, and it is found that the Boussinesq system predicts larger wave run-up than the shallow-water theory in the example treated in this paper. It is also found that the finite fluid domain has a significant impact on the behavior of the wave run-up.

  2. Boussinesq modeling of surface waves due to underwater landslides

    CERN Document Server

    Dutykh, Denys

    2013-01-01

    Consideration is given to the influence of an underwater landslide on waves at the surface of a shallow body of fluid. The equations of motion which govern the evolution of the barycenter of the landslide mass include various dissipative effects due to bottom friction, internal energy dissipation, and viscous drag. The surface waves are studied in the Boussinesq scaling, with time-dependent bathymetry. A numerical model for the Boussinesq equations is introduced which is able to handle time-dependent bottom topography, and the equations of motion for the landslide and surface waves are solved simultaneously. The numerical solver for the Boussinesq equations can also be restricted to implement a shallow-water solver, and the shallow-water and Boussinesq configurations are compared. A particular bathymetry is chosen to illustrate the general method, and it is found that the Boussinesq system predicts larger wave run-up than the shallow-water theory in the example treated in this paper. It also found that the fi...

  3. Water availability and land subsidence in the Central Valley, California, USA

    Science.gov (United States)

    Faunt, Claudia; Sneed, Michelle; Traum, Jonathan A.; Brandt, Justin

    2016-01-01

    The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

  4. Water availability and land subsidence in the Central Valley, California, USA

    Science.gov (United States)

    Faunt, Claudia C.; Sneed, Michelle; Traum, Jon; Brandt, Justin T.

    2016-05-01

    The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007-2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

  5. Integrating interferometric SAR data with levelling measurements of land subsidence using geostatistics

    NARCIS (Netherlands)

    Zhou, Y.; Stein, A.; Molenaar, M.

    2003-01-01

    Differential Synthetic Aperture Radar (SAR) interferometric (D-InSAR) data of ground surface deformation are affected by several error sources associated with image acquisitions and data processing. In this paper, we study the use of D-InSAR for quantifying land subsidence due to groundwater extract

  6. Research of the refilling use in order to reduce the subsidence effects in the surface; Investigacion del Empleo de Relleno Consolidado para Reducir los Efectos de la Subsidencia en Superficie

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The development of the research has been performed with a practical immediate purpose in the works of the Company Coto Minero de Narcea, S. A., a producer of anthracite in Asturias West Bassin. This is due to the fact that the work mining of the 2, 3 and 6 seams, essential to continue the production activities, is at present almost in vertical coincidence with surface installations of the mine making it necessary to use a filling material specially selected and layed in the works to minimize the subsidence effects. The prediction of these effects in order to reduce them to admissible bounds has been made through the application of the computer program SUBSIMCO, developed on the basis of the empirical calculation methods and the experience collected by the VNIMI Institute of Leningrad. The results controlled up to now, through accurate measuring, show a satisfactory coincidence with the predictions of theoretical calculations, proving at the same time the effectiveness of the filling process designed and the correct adaptation of the calculus method.

  7. Effectiveness of submerged drains in reducing subsidence of peat soils in agricultural use, and their effects on water management and nutrient loading of surface water: modelling of a case study in the western peat soil area of The Netherlands

    Science.gov (United States)

    Hendriks, Rob F. A.; van den Akker, Jan J. A.

    2017-04-01

    Effectiveness of submerged drains in reducing subsidence of peat soils in agricultural use, and their effects on water management and nutrient loading of surface water: modelling of a case study in the western peat soil area of The Netherlands In the Netherlands, about 8% of the area is covered by peat soils. Most of these soils are in use for dairy farming and, consequently, are drained. Drainage causes decomposition of peat by oxidation and accordingly leads to surface subsidence and greenhouse gas emission. Submerged drains that enhance submerged infiltration of water from ditches during the dry and warm summer half year were, and are still, studied in The Netherlands as a promising tool for reducing peat decomposition by raising groundwater levels. For this purpose, several pilot field studies in the Western part of the Dutch peat area were conducted. Besides the effectiveness of submerged drains in reducing peat decomposition and subsidence by raising groundwater tables, some other relevant or expected effects of these drains were studied. Most important of these are water management and loading of surface water with nutrients nitrogen, phosphorus and sulphate. Because most of these parameters are not easy to assess and all of them are strongly depending on the meteorological conditions during the field studies some of these studies were modelled. The SWAP model was used for evaluating the hydrological results on groundwater table and water discharge and recharge. Effects of submerged drains were assessed by comparing the results of fields with and without drains. An empirical relation between deepest groundwater table and subsidence was used to convert effects on groundwater table to effects on subsidence. With the SWAP-ANIMO model nutrient loading of surface water was modelled on the basis of field results on nutrient concentrations . Calibrated models were used to assess effects in the present situation, as thirty-year averages, under extreme weather

  8. Geomechanics of subsidence above single and multi-seam coal mining

    Institute of Scientific and Technical Information of China (English)

    A.M. Suchowerska Iwanec; J.P. Carter; J.P. Hambleton

    2016-01-01

    Accurate prediction of surface subsidence due to the extraction of underground coal seams is a significant challenge in geotechnical engineering. This task is further compounded by the growing trend for coal to be extracted from seams either above or below previously extracted coal seams, a practice known as multi-seam mining. In order to accurately predict the subsidence above single and multi-seam longwall panels using numerical methods, constitutive laws need to appropriately represent the mechanical behaviour of coal measure strata. The choice of the most appropriate model is not always straightforward. This paper compares predictions of surface subsidence obtained using the finite element method, considering a range of well-known constitutive models. The results show that more sophisticated and numerically taxing constitutive laws do not necessarily lead to more accurate predictions of subsidence when compared to field measurements. The advantages and limitations of using each particular constitutive law are discussed. A comparison of the numerical predictions and field measurements of surface subsidence is also provided.

  9. Geomechanics of subsidence above single and multi-seam coal mining

    Directory of Open Access Journals (Sweden)

    A.M. Suchowerska Iwanec

    2016-06-01

    Full Text Available Accurate prediction of surface subsidence due to the extraction of underground coal seams is a significant challenge in geotechnical engineering. This task is further compounded by the growing trend for coal to be extracted from seams either above or below previously extracted coal seams, a practice known as multi-seam mining. In order to accurately predict the subsidence above single and multi-seam longwall panels using numerical methods, constitutive laws need to appropriately represent the mechanical behaviour of coal measure strata. The choice of the most appropriate model is not always straightforward. This paper compares predictions of surface subsidence obtained using the finite element method, considering a range of well-known constitutive models. The results show that more sophisticated and numerically taxing constitutive laws do not necessarily lead to more accurate predictions of subsidence when compared to field measurements. The advantages and limitations of using each particular constitutive law are discussed. A comparison of the numerical predictions and field measurements of surface subsidence is also provided.

  10. Sinkhole formation and subsidence along the Dead Sea coast, Israel

    Science.gov (United States)

    Yechieli, Yoseph; Abelson, Meir; Baer, Gideon

    2016-05-01

    More than 4,000 sinkholes have formed since the 1980s within a 60-km-long and 1-km-wide strip along the western coast of the Dead Sea (DS) in Israel. Their formation rate accelerated in recent years to >400 sinkholes per year. They cluster mostly in specific sites up to 1,000 m long and 200 m wide, which align parallel to the general direction of the fault systems associated with the DS Rift. The abrupt appearance of the sinkholes reflects changes to the groundwater regime around the shrinking DS. The eastward retreat of the shoreline and the lake-level drop (1 m/year in recent years) cause an eastward and downward migration of the fresh/saline groundwater interface. Consequently, a subsurface salt layer, which was previously enveloped by saline groundwater, is gradually being invaded and submerged by relatively fresh groundwater, and cavities form due to the rapid dissolution of the salt. Collapse of the overlying sediments into these cavities results in sinkholes at the surface. An association between sinkhole sites and land subsidence is revealed by interferometric synthetic aperture radar (InSAR) measurements. On a broad scale (hundreds of meters), subsidence occurs due to compaction of fine-grained sediments as groundwater levels decline along the retreating DS shoreline. At smaller scales (tens of meters), subsidence appears above subsurface cavities in association with the sinkholes, serving in many cases as sinkhole precursors, a few weeks to more than a year before their actual appearance at the surface. This paper overviews the processes of sinkhole formation and their relation to land subsidence.

  11. Detecting, mapping and monitoring of land subsidence in Jharia Coalfield, Jharkhand, India by spaceborne differential interferometric SAR, GPS and precision levelling techniques

    Indian Academy of Sciences (India)

    R S Chatterjee; Shailaja Thapa; K B Singh; G Varunakumar; E V R Raju

    2015-08-01

    The study aims at detection, mapping and monitoring of land subsidence in Jharia Coalfield, Jharkhand, India by spaceborne DInSAR, GPS and precision levelling techniques. Using multi-frequency C- and L-band DInSAR, both slowly and rapidly subsiding areas were identified and DInSAR-based subsidence maps were prepared. C-band DInSAR was found useful for detection of slowly subsiding areas whereas L-band DInSAR for rapidly subsiding and/or adverse land cover areas. Due to dynamic nature of mining and adverse land cover, temporal decorrelation poses a serious problem particularly in C-band DInSAR. Specially designed InSAR coherence guided adaptive filtering was found useful to highlight the deformation fringes. Collateral GPS and levelling observations were conducted in three test sites to validate DInSAR measurements and to determine the net displacement vectors. We observed an appreciable horizontal displacement component of land subsidence in all the test sites. For comparison of results, we calculated InSAR coherence weighted LOS displacement rates from the unwrapped differential interferograms of smaller spatial subsets and LOS projected ground-based displacement rates in three test sites. We found good agreement between DInSAR and ground-based measurements except for C-band observation in Dobari test site primarily due to large difference in observation periods and temporally inconsistent land subsidence. Collateral spaceborne and ground-based observations were also found useful for characterization of subsidence phenomena to determine net displacement vector and horizontal displacement component. In coal mining areas with spatially scattered and temporally irregular land subsidence phenomena, the adopted methodology can be used successfully for detection, mapping and monitoring of the subsiding areas vulnerable to future collapse. This will facilitate efficient planning and designing of surface infrastructures and other developmental structures in the mining

  12. A new soil mechanics approach to quantify and predict land subsidence by peat compression

    Science.gov (United States)

    Koster, Kay; Erkens, Gilles; Zwanenburg, Cor

    2016-10-01

    Land subsidence threatens many coastal areas. Quantifying current and predicting future subsidence are essential to sustain the viability of these areas with respect to rising sea levels. Despite its scale and severity, methods to quantify subsidence are scarce. In peat-rich subsidence hot spots, subsidence is often caused by peat compression. We introduce the standard Cone Penetration Test (CPT) as a technique to quantify subsidence due to compression of peat. In a test in the Holland coastal plain, the Netherlands, we found a strong relationship between thickness reduction of peat and cone resistance, due to an increase in peat stiffness after compression. We use these results to quantify subsidence of peat in subsiding areas of Sacramento-San Joaquin delta and Kalimantan, and found values corresponding with previously made observations. These results open the door for CPT as a new method to document past and predict future subsidence due to peat compression over large areas.

  13. SHAPE BIFURCATION OF AN ELASTIC WAFER DUE TO SURFACE STRESS

    Institute of Scientific and Technical Information of China (English)

    闫琨; 何陵辉; 刘人怀

    2003-01-01

    A geometrically nonlinear analysis was proposed for the deformation of a freestanding elastically isotropic wafer caused by the surface stress change on one surface. Thelink between the curvature and the change in surface stress was obtained analytically fromenergetic consideration. In contrast to the existing linear analysis, a remarkableconsequence is that, when the wafer is very thin or the surface stress difference between thetwo major surfaces is large enough, the shape of the wafer will bifurcate.

  14. Integrated geophysical survey in defining subsidence features on a golf course

    Science.gov (United States)

    Xia, Jianghai; Miller, Richard D.

    2007-12-01

    Subsidence was observed at several places on the Salina Municipal Golf Course in areas known to be built over a landfill in Salina, Kansas. High-resolution magnetic survey (~5400 m2), multi-channel electrical resistivity profiling (three 154 m lines) and microgravity profiling (23 gravity-station values) were performed on a subsidence site (Green 16) to aid in determining boundaries and density deficiency of the landfill in the vicinity of the subsidence. Horizontal boundaries of the landfill were confidently defined by both magnetic anomalies and the pseudo-vertical gradient of total field magnetic anomalies. Furthermore, the pseudo-vertical gradient of magnetic anomalies presented a unique anomaly at Green 16, which provided a criterion for predicting other spots with subsidence potential using the same gradient property. Results of multi-channel electrical resistivity profiling (ERP) suggested the bottom limit of the landfill at Green 16 was around 21 m below the ground surface based on the vertical gradient of electric resistivity and a priori information on the depth of the landfill. ERP results also outlined several possible landfill bodies based on their low resistivity values. Microgravity results suggested a -0.14 g cm-3 density deficiency at Green 16 that could equate to future surface subsidence of as much as 1.5 m due to gradual compaction.

  15. Integrated geophysical survey in defining subsidence features on a golf course

    Science.gov (United States)

    Xia, J.; Miller, R.D.

    2007-01-01

    Subsidence was observed at several places on the Salina Municipal Golf Course in areas known to be built over a landfill in Salina, Kansas. High-resolution magnetic survey (???5400 m2), multi-channel electrical resistivity profiling (three 154 m lines) and microgravity profiling (23 gravity-station values) were performed on a subsidence site (Green 16) to aid in determining boundaries and density deficiency of the landfill in the vicinity of the subsidence. Horizontal boundaries of the landfill were confidently defined by both magnetic anomalies and the pseudo-vertical gradient of total field magnetic anomalies. Furthermore, the pseudo-vertical gradient of magnetic anomalies presented a unique anomaly at Green 16, which provided a criterion for predicting other spots with subsidence potential using the same gradient property. Results of multi-channel electrical resistivity profiling (ERP) suggested the bottom limit of the landfill at Green 16 was around 21 m below the ground surface based on the vertical gradient of electric resistivity and a priori information on the depth of the landfill. ERP results also outlined several possible landfill bodies based on their low resistivity values. Microgravity results suggested a -0.14 g cm-3 density deficiency at Green 16 that could equate to future surface subsidence of as much as 1.5 m due to gradual compaction. ?? 2007 Nanjing Institute of Geophysical Prospecting.

  16. Analysis of long-term land subsidence near Mexico City: Field investigations and predictive modeling

    Science.gov (United States)

    Ortega-Guerrero, Adrian; Rudolph, David L.; Cherry, John A.

    1999-11-01

    The Mexico City region has several flat plains formed on exceptionally porous (60-90%) lacustrine deposits overlying a highly productive regional aquifer. Severe land subsidence due to consolidation of the lacustrine aquitard caused by aquifer exploitation has resulted in restrictions on pumping in the core of Mexico City. This has led to large increases in aquifer pumping in the outlying lacustrine plains where satellite communities are rapidly expanding. The Chalco Basin is one of these lacustrine areas where pumping began in the 1950s and greatly increased in the 1980s. The lacustrine sequence in the Chalco area is significantly thicker than anywhere else in the Basin of Mexico averaging 100 m and reaching a maximum thickness of 300 m. Consequently, this area is susceptible to the highest potential land subsidence effects as a result of groundwater extraction of anywhere in the basin. Land subsidence in the central part of the Chalco Basin has increased to 0.4 m/yr since 1984 and by 1991 total subsidence had reached 8 m. The rapid land subsidence in this area is causing the accumulation of meteoric waters during the rainy season resulting in extensive flooding of farmland. This study first demonstrates a methodology for combining hydraulic data from a network of monitoring wells, geotechnical data from core samples, and a compilation of historical information on land surface elevation to quantify groundwater flow and land subsidence phenomena within the rapidly subsiding Chalco Basin. Then a one-dimensional mathematical model is employed to develop predictions of future land subsidence under a range of pumping conditions. The model permits the hydraulic properties of the aquitard to vary as transient functions of hydraulic head and porosity. Simulations suggest that under current pumping rates, total land subsidence in the area of thickest lacustrine sediment will reach 15 m by the year 2010. If pumping is reduced to the extent that further decline in the

  17. Application of Kalman filtering in monitoring of surface subsidence by the observation station%Kalman滤波在地表移动观测站沉降监测中的应用研究

    Institute of Scientific and Technical Information of China (English)

    吕伟才; 秦永洋; 孙兴平; 郭红星

    2011-01-01

    According to Kalman filtering theory and the needs of mining subsidence monitoring, the standard Kalman filtering model and predicting model of the surface subsidence are advanced which is monitored by the surface displacement observation station. These models are tested by the data from the 1117(1) First Exploiting Face Observation Station in Guqiao Mine, and meet the requirement for mining subsidence management engineering.%文章根据Kalman滤波理论,结合矿区开采沉陷监测的需要,建立了对地表移动观测站沉降监测进行动态处理的标准Kalman滤波模型和预测预报模型;利用顾桥矿1117(1)首采面观测站的实测资料,对所建立的滤波模型和预测预报模型进行了检核,结果表明所建模型基本能满足开采沉陷工程治理的要求.

  18. Analysis of Subsidence Data for the Big Hill Site, Texas

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Stephen J.

    1999-06-01

    The elevation change data measured at the Big Hill SPR site over the last 10 years has been studied and a model utilized to project elevation changes into the future. The subsidence rate at Big Hill is low in comparison with other Strategic Petroleum Reserve sites and has decreased with time due to the maintenance of higher operating pressures and the normal decrease in creep closure rate of caverns with time. However, the subsidence at the site is projected to continue. A model was developed to project subsidence values 20 years into the future; no subsidence related issues are apparent from these projections.

  19. Consideration on the restoring plan in the subsidence prone areas through the development of ground stability assessment techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.S.; Kim, I.H.; Cho, W.J.; Song, W.K.; Synn, J.H.; Choi, S.O.; Yoon, C.H.; Hong, K.P.; Park, C. [Korea Institute of Geology Mining and Materials, Taejon (Korea)

    1998-12-01

    The ground stability assessment technique of the subsidence prone area and its restoring plan need to be developed to obtain the ground stability around the mines at rest or closed since 1980's. Up to the present, the assessment of the subsidence risk has been conducted only after the statements of residents or the observation of symptom on the subsidence. Generally, the assessment process at first stage is carried on through the analysis of surface and mining map, the geological survey and the interviews to the residents. Drilling survey, rock property test, geotechnical rock and ground survey, and numerical analyses belong to the second stage. After the completion of the procedure the stability of buildings and the strength of subsidence are determined. The acquisition of the accurate in-situ data, the estimation of mechanical property of rock mass, and the analysis of basic mechanism may affect in the great extent on the assessment of the subsidence risk. In this study, the development of the subsidence risk assessment method was incorporated with the GIS technique which will be used to make the risk information map on the subsidence. The numerical analysis in 2D and 3D using PFC and FLAC has been conducted to estimate the ground stability of Moo-Geuk Mine area. The displacement behavior of the ground and the development of the failed zone due to the cavity were studied from the numerical modelling. The result of the ground stability assessment for the area in question shows that the risk to the subsidence is relatively small. It is, however, necessary to fill the cavity with some suitable materials when considering the new construction of buildings or roads in plan. Finally, the measures to prevent the subsidence and some case studies were presented, in particular the case study on the measurement of the ground movement in a mine were described in detail. (author). 27 refs., 27 tabs., 62 figs.

  20. Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

    KAUST Repository

    Keiding, Marie

    2010-07-01

    We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

  1. Using temporarily coherent point interferometric synthetic aperture radar for land subsidence monitoring in a mining region of western China

    Science.gov (United States)

    Fan, Hongdong; Xu, Qiang; Hu, Zhongbo; Du, Sen

    2017-04-01

    Yuyang mine is located in the semiarid western region of China where, due to serious land subsidence caused by underground coal exploitation, the local ecological environment has become more fragile. An advanced interferometric synthetic aperture radar (InSAR) technique, temporarily coherent point InSAR, is applied to measure surface movements caused by different mining conditions. Fifteen high-resolution TerraSAR-X images acquired between October 2, 2012, and March 27, 2013, were processed to generate time-series data for ground deformation. The results show that the maximum accumulated values of subsidence and velocity were 86 mm and 162 mm/year, respectively; these measurements were taken above the fully mechanized longwall caving faces. Based on the dynamic land subsidence caused by the exploitation of one working face, the land subsidence range was deduced to have increased 38 m in the mining direction with 11 days' coal extraction. Although some mining faces were ceased in 2009, they could also have contributed to a small residual deformation of overlying strata. Surface subsidence of the backfill mining region was quite small, the maximum only 21 mm, so backfill exploitation is an effective method for reducing the land subsidence while coal is mined.

  2. Accumulation of Microswimmers due to Their Collisions with a Surface

    CERN Document Server

    Li, Guanglai

    2008-01-01

    In this letter we propose a kinematic model to show how collisions with a surface and rotational Brownian motion give rise to the accumulation of micro-swimmers near a surface. In this model, an elongated microswimmer invariably travels parallel to the surface after hitting it from any incident angle. It then swims away from the surface after some time, facilitated by rotational Brownian motion. Simulations based on this model reproduce the density distributions measured for the small bacteria E. coli and Caulobacter crescentus, as well as for the much larger bull spermatozoa swimming in confinement.

  3. 基于短基线集技术的矿区开采沉陷监测研究%Monitoring the Surface Subsidence of Mining Areas Based on SBAS Method

    Institute of Scientific and Technical Information of China (English)

    李国华; 薛继群

    2013-01-01

    The surface subsidence monitoring of mining areas becomes increasingly important because of the large - scale exploitation of coal resources. As an important branch of Differential Interferometry Synthetic Aperture Radar (D - InSAR) , Small Baseline Subset (SBAS) method has been presented as an effective way to monitor the urban surface deformation theoretically, which is based on the use of a large number of SAR acquisitions distributed in small baseline subsets and singular value decomposition ( SVD) method, but has not been used to monitor mine subsidence. In this paper, an experiment based on the SBAS method was performed to monitor mine subsidence using 12 ERS - 1/2 SAR images of mining area in Jiangsu. Experimental results show that this method can effectively monitor the mine surface subsidence to a certain extent, but at present stage, the result of SBAS method can not achieve the desired application standard. According to the experimental result, we summarized two factors which restrict SBAS technique applied to monitor mining subsidence.%随着矿产资源的开采规模、范围不断增加,监测矿区开采沉陷显得越来越重要.作为差分干涉测量技术(D-InSAR)的重要分支,短基线技术(Small Baseline Subset,SBAS)理论上能有效地监测城市沉降,但未应用于监测矿区的开采沉陷.它是将多幅SAR影像组合成若干个基线距较短的干涉对并利用奇异值分解(SVD)方法获取形变.本文利用12幅ERS-1/2 SAR影像(1995.4-1998.8)组成20组干涉对,采用短基线技术对江苏某矿区的开采沉陷进行监测.实验表明,短基线技术能较为有效地监测矿区的开采沉陷,但在现阶段尚不能应用于生产工作中.根据本次实验结果,总结出限制短基线技术应用于监测矿区开采沉陷的两大因素.

  4. Planetary plains: subsidence and warping

    Science.gov (United States)

    Kochemasov, G.

    A common feature of all celestial bodies is their tectonic dichotomy best studied, naturally, at Earth [1]. Here there is an opposition of the eastern continental hemisphere and the western oceanic one. The first one is uplifted and cracked, the second one subsided, squeezed and warped. The next excellent example of dichotomy is at Mars where the subsided northern hemisphere is opposed by the highly uplifted southern one. The enigmatic two-face Iapetus now with help of Cassini SC presents a more clear picture: the leading dark hemisphere is opposed by the trailing light one. The light hemisphere is built mainly of water ice, the dark one of some more dense material. Bean-shaped asteroids with one convex and another concave hemispheres are best exemplified by Ida. Examples of dichotomic asteroids, satellites, planets and stars could be extended. Ubiquity of this phenomenon was expressed as the 1st theorem of the planetary wave tectonics [2 & others]: "Celestial bodies are dichotomic". A reason of this phenomenon is in action of inertia-gravity waves occurring in any celestial body because of its movement in non-round but elliptical (parabolic) orbit with periodically changing accelerations. The inertia-gravity standing waves warp rotating bodies (but all bodies rotate !) in 4 ortho- and diagonal interfering directions and in several harmonic wave-lengths. The fundamental wave1 produces ubiquitous tectonic dichotomy (2πR-structure): an opposition of two hemispheres with different planetary radii. To keep angular momenta of two hemispheres equal (otherwise a body will fall apart) the lower subsiding one is constructed of denser material than the higher one. Normally in terrestrial planets lowlands are filled with dense basalts, highlands are built by lighter lithologies. A subsidence means diminishing radius, otherwise, the larger surface must be fit into a smaller space. It is possible only if an original infilling is warped. At Earth cosmic altimetry shows complex

  5. Time series prediction of mining subsidence based on a SVM

    Institute of Scientific and Technical Information of China (English)

    Li Peixian; Tan Zhixiang; Yah Lili; Deng Kazhong

    2011-01-01

    In order to study dynamic laws of surface movements over coal mines due to mining activities,a dynamic prediction model of surface movements was established,based on the theory of support vector machines (SVM) and times-series analysis.An engineering application was used to verify the correctness of the model.Measurements from observation stations were analyzed and processed to obtain equal-time interval surface movement data and subjected to tests of stationary,zero means and normality.Then the data were used to train the SVM model.A time series model was established to predict mining subsidence by rational choices of embedding dimensions and SVM parameters.MAPE and WIA were used asindicators to evaluate the accuracy of the model and for generalization performance.In the end,the model was used to predict future surface movements.Data from observation stations in Huaibei coal mining area were used as an example.The results show that the maximum absolute error of subsidence is 9 mm,the maximum relative error 1.5%.the maximum absolute error of displacement 7 mm and the maximum relative error 1.8%.The accuracy and reliability of the model meet the requirements of on-site engineering.The results of the study provide a new approach to investigate the dynamics of surface movements.

  6. Development of a complex groundwater model to assess the relation among groundwater resource exploitation, seawater intrusion and land subsidence

    Science.gov (United States)

    Hsi Ting, Fang; Yih Chi, Tan; Chen, Jhong Bing

    2016-04-01

    The land subsidence, which is usually irreversible, in Taiwan Pintung Plain occurred due to groundwater overexploitation. Many of the land subsidence areas in Taiwan are located in coastal area. It could not only result in homeland loss, but also vulnerability to flooding because the function of drainage system and sea wall are weakened for the lowered ground surface. Groundwater salinization and seawater intrusion could happen more easily as well. This research focuses on grasping the trend of environmental change due to the damage and impact from inappropriate development of aquaculture in the last decades. The main task is developing the artificial neural networks (ANNs) and complex numerical model for conjunctive use of surface and groundwater which is composed of a few modules such as land use, land subsidence, contamination transportation and etc. An approach based on self-organizing map (SOM) is proposed to delineate groundwater recharge zones. Several topics will be studied such as coupling of surface water and groundwater modeling, assessing the benefit of improving groundwater resources by recharge, identifying the improper usage of groundwater resources, and investigating the effect of over-pumping on land subsidence in different depth. In addition, a complete plan for managing both the flooding and water resources will be instituted by scheming non-engineering adaptation strategies for homeland planning, ex. controlling pumping behavior in area vulnerable to land subsidence and increasing groundwater recharge.

  7. Enhanced diffusion due to active swimmers at a solid surface

    CERN Document Server

    Miño, Gaston; Darnige, Thierry; Hoyos, Mauricio; Dauchet, Jeremy; Dunstan, Jocelyn; Soto, Rodrigo; Wang, Yang; Rousselet, Annie; Clement, Eric

    2010-01-01

    We consider two systems of active swimmers moving close to a solid surface, one being a living population of wild-type \\textit{E. coli} and the other being an assembly of self-propelled Au-Pt rods. In both situations, we have identified two different types of motion at the surface and evaluated the fraction of the population that displayed ballistic trajectories (active swimmers) with respect to those showing random-like behavior. We studied the effect of this complex swimming activity on the diffusivity of passive tracers also present at the surface. We found that the tracer diffusivity is enhanced with respect to standard Brownian motion and increases linearly with the activity of the fluid, defined as the product of the fraction of active swimmers and their mean velocity. This result can be understood in terms of series of elementary encounters between the active swimmers and the tracers.

  8. Land subsidence in the Santa Clara Valley, California as of 1980

    Science.gov (United States)

    Poland, J.F.; Ireland, R.L.

    1984-01-01

    From 1916 to 1966 in the San Jose area of Santa Clara Valley, California, deficient rainfall and runoff was accompanied by a fourfold increase in groundwater withdrawals. In response the artesian head declined 180-240 ft. The land surface subsided 12.7 ft in San Jose, due to compaction of the fine-grained compressible beds. The subsidence resulted in flooding of lands, and the compaction of the sediments caused compressional failure of many well casings. From 1967 to 1975, the artesian head recovered 70 to 100 feet due to a fivefold increase in surface water imports, favorable local water supply, decreased withdrawal, and increased recharge. In 1960, the Geological Survey installed extensometers in core holes 1,000 ft deep in San Jose and Sunnyvale. Measurements of compaction of the confined aquifer system obtained from these extensometers demonstrate the marked decrease in rate of compaction in response to the major head recovery since 1967. In San Jose the rate decreased from about 1 ft/yr in 1961 to 0.1 ft/yr in 1973. The subsidence has been stopped by raising the artesian head in the aquifers until it equaled or exceeded the maximum pore pressures in the fine-grained beds. However, the subsidence will recommence if the artesian head is drawn down appreciably below the levels of 1971-73. (USGS)

  9. Safety appraisement on building natural gas pipeline over coal mining subsidence area

    Institute of Scientific and Technical Information of China (English)

    GUO Wei-jia; LIU Jin-xiao; WEN Xing-lin

    2007-01-01

    The target of the text is to scientifically appraise dynamic development of surface deformation in subsidence area and its influence on groundwork stability of natural pipe and then adopt some technological measures to ensure safe circulation of natural pipeline. Analysed the influence on natural pipeline from coal mining subsidence in the way of pipeline grade variation, vertical curve variation, transverse deformation, horizontal pull and compression deformation and pipe stress variation etc., and described detailed surface subsidence product and its used time among initial phase, active phase and decline phase in the course of surface movement deformation time. In the context of considering surface subsidence that doesn't reach basic latter end and residual subsidence quantity, the text confirmed the calculation method of residual deformation in surface subsidence area, and gave the technological measures about building natural gas pipeline in subsidence area finally.

  10. Vertical Crustal Displacements Due to Surface Fluid Changes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shiyu; ZHONG Min

    2007-01-01

    Using the model data for surface mass changes of the atmosphere, ocean, soil moisture and snow depth, the vertical crustal displacements of 25 ficual stations in China were calculated according to the loading theory. From the spectral analysis of the results, we can see that the periods of displacements are 12 months and the semi-periods are 6 months. The results also show that the maximum seasonal displacements can reach 20 mm and even larger. The covariance analyses and significance tests show that the coefficients of 96 percent of the stations are significant at the 0.1 significance level. The results show that one of the reasons of the vertical crustal displacements is the changing surface fluid loads.

  11. Measurement of Mode Interaction Due to Waveguide Surface Roughness.

    Science.gov (United States)

    1984-12-01

    Speed of Mode 1 over Wedge Roughness at 7813 Hz Due to Cycle Error q. 104 q cprI (mis) Cr r 100M% -2 335.33 6.94 -1 346.16 3.93 0 357.73 0.72 1370.07...4.4 Mode 2 Energy Attenuation Freq (Hz) Smooth (dB/m) Rough (dB/m) 7750 2.0 4.8 15750 2.8 10.5 23500 3.5 12.2 31250 4.3 10.1 110 c -c q CprI (m/s) .pr... cprI x 100(%)C pr -1 377.30 1.86 0 398.58 -3.68 Table 35. Change in Phase Speed of Mode I over Random Roughness at 7750 Hz Due to Cycle Error q. 124

  12. Groundwater Resources and Land Subsidence investigations in the Toluca Valley, Mexico

    Science.gov (United States)

    Calderhead, A. I.; Martel, R.; Rivera, A.; Garfias, J.; Therrien, R.

    2007-05-01

    The sustained growth in population in the Toluca Valley and neighboring Mexico City has primarily depended on the continuous development of both local and regional water resources for industrial, agricultural and domestic uses. The Toluca Valley Basin, covering an area of approximately 2000 Km2, is the focus of this study. Currently, there is a significant net loss of water within the basin primarily due to groundwater pumping, and the loss is increasing with time. These stresses on the aquifer have caused significant changes on the water flow patterns, a reversal in the direction of hydraulic gradients, the disappearance of artesian springs and wetlands and noticeable land subsidence within the basin. Neighboring Mexico City's land subsidence problems have been well documented, however, no comprehensive studies exist for the Toluca Basin. This study is divided into two parts: 1) investigation of groundwater depletion in the Toluca Valley; and 2) assessment of land subsidence in the Toluca Valley. We examine various changes in regional flow patterns, and groundwater levels decline throughout the valley and 3D numerical flow simulations are run to predict the ever decreasing level of the piezometric surface. Currently there is a net loss (recharge - extraction) of 142 Mm3 per year of groundwater within the Toluca Basin aquifers. We have documented a decrease in groundwater levels with a rate of up to 1.4 m/year between 1970 and 2006 in the central part of the valley. At the current rate of consumption, groundwater resources will not be sustainable for the population of the valley. Directly related to the drawdown in groundwater levels is the occurrence of land subsidence throughout the valley. Neighboring Mexico City, where total subsidence of up to 9 meters has been observed, has a similar geology as the one in the Toluca valley. We have documented several sites in the Toluca Valley where land subsidence is occurring. Ongoing work includes the mapping of regional

  13. Ground Subsidence in Areas of Loose Porous Aquifers

    Institute of Scientific and Technical Information of China (English)

    LI Yixiang; GAO Guanhua

    2004-01-01

    Groundwater is one of the important water resources in northern China's plain areas. Many severe geological hazards have occurred in these areas due to ground subsidence which is caused by over exploitation of groundwater. This paper introduces and analyses the ground subsidence caused by groundwater exploitation and its mechanism in the northern China's plains. A ground subsidence prediction model has been developed based on the consolidation theory. The authors have tested this model in a case study of Fuyang City, Anhui Province, where ground subsidence is a severe environmental problem. In the case study, the model results match very well with those of the actual measurement. Two schemes of groundwater exploitation are assessed. The conclusion from the study could be used in the long-term water and economical management planning. The strategies for the control of ground subsidence are discussed.

  14. Seismic reflection characteristics of naturally-induced subsidence affecting transportation

    Science.gov (United States)

    Miller, R.D.; Xia, J.; Steeples, D.W.

    2009-01-01

    High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipelines can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure. ?? China University of Geosciences (Wuhan) and Springer-Verlag GmbH 2009.

  15. Seismic Reflection Characteristics of Naturally-Induced Subsidence Affecting Transportation

    Institute of Scientific and Technical Information of China (English)

    Richard D Miller; Jianghai Xia; Don W Steeples

    2009-01-01

    High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipeliues can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure.

  16. Subsidence Modeling of the Over-exploited Granular Aquifer System in Aguascalientes, Mexico

    Science.gov (United States)

    Solano Rojas, D. E.; Wdowinski, S.; Minderhoud, P. P. S.; Pacheco, J.; Cabral, E.

    2016-12-01

    The valley of Aguascalientes in central Mexico experiences subsidence rates of up to 100 [mm/yr] due to overexploitation of its aquifer system, as revealed from satellite-based geodetic observations. The spatial pattern of the subsidence over the valley is inhomogeneous and affected by shallow faulting. The understanding of the subsoil mechanics is still limited. A better understanding of the subsidence process in Aguascalientes is needed to provide insights for future subsidence in the valley. We present here a displacement-constrained finite-element subsidence model using Deltares iMOD (interactive MODeling), based on the USGS MODFLOW software. The construction of our model relies on 3 main inputs: (1) groundwater level time series obtained from extraction wells' hydrographs, (2) subsurface lithostratigraphy interpreted from well drilling logs, and (3) hydrogeological parameters obtained from field pumping tests. The groundwater level measurements were converted to pore pressure in our model's layers, and used in Terzaghi's equation for calculating effective stress. We then used the effective stresse along with the displacement obtained from geodetic observations to constrain and optimize five geo-mechanical parameters: compression ratio, reloading ratio, secondary compression index, over consolidation ratio, and consolidation coefficient. Finally, we use the NEN-Bjerrum linear stress model formulation for settlements to determine elastic and visco-plastic strain, accounting for the aquifer system units' aging effect. Preliminary results show higher compaction response in clay-saturated intervals (i.e. aquitards) of the aquifer system, as reflected in the spatial pattern of the surface deformation. The forecasted subsidence for our proposed scenarios show a much more pronounced deformation when we consider higher groundwater extraction regimes.

  17. The UNESCO-IHP Working Group on Land Subsidence: Four Decades of International Contributions to Hydrogeological Related Subsidence Research and Knowledge Exchange

    Science.gov (United States)

    Galloway, D. L.; Carreon-Freyre, D.; Teatini, P.; Ye, S.

    2015-12-01

    Subsidence is globally prevalent and because much of it is related to hydrological processes affected by human development of local land and water resources, "Land Subsidence" was included in the UNESCO programme of the International Hydrological Decade (IHD), 1965-1974 and an ad hoc working group on land subsidence was formed. In 1975 subsidence was retained under the framework of the UNESCO IHP (subproject 8.4: "Investigation of Land Subsidence due to Groundwater Exploitation"), and UNESCO IHP formerly codified the Working Group on Land Subsidence (WGLS). In 1984 the WGLS produced a comprehensive guidebook to serve scientists and engineers, confronting land subsidence problems, particularly in developing countries (http://unesdoc.unesco.org/$other/unesdoc/pdf/065167eo.pdf). During the IHD, UNESCO IHP convened the 1st International Symposium on Land Subsidence in 1969 in Tokyo, Japan. In collaboration with UNESCO IHP, IAHS, and other scientific organizations, the WGLS has convened eight more International Symposia on Land Subsidence in different countries in Asia, Europe and North America. The 9 published symposia proceedings constitute an important source of global subsidence research and case studies during the past 45 years, covering both anthropogenic and natural subsidence processes. Currently, the WGLS comprising 20 subsidence experts from 9 countries promotes and facilitates the international exchange of information regarding the design, implementation and evaluation of risk assessments and mitigation measures, the definition of water and land resource-management strategies that support sustainable development in areas vulnerable to subsidence (http://landsubsidence-unesco.org), and the assessment of related geological risks such as earth fissuring and fault activation (www.igcp641.org). The WGLS has become an important global leader in promoting subsidence awareness, scientific research and its application to subsidence monitoring, analysis and management.

  18. Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

    NARCIS (Netherlands)

    Marketos, G.; Spiers, C.J.; Govers, R.

    2016-01-01

    Accurate forward modeling of surface subsidence above producing hydrocarbons reservoirs requires an understanding of the mechanisms determining how ground deformation and subsidence evolve. Here we focus entirely on rock salt, which overlies a large number of reservoirs worldwide, and specifically

  19. Detecting and Measuring Land Subsidence in Houston-Galveston, Texas using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System Data, 2012-2016

    Science.gov (United States)

    Reed, A.; Baker, S.

    2016-12-01

    Several cities in the Houston-Galveston (HG) region in Texas have subsided up to 13 feet over several decades due to natural and anthropogenic processes [Yu et al. 2014]. Land subsidence, a gradual sinking of the Earth's surface, is an often human-induced hazard and a major environmental problem expedited by activities such as mining, oil and gas extraction, urbanization and excessive groundwater pumping. We are able to detect and measure subsidence in HG using interferometric synthetic aperture radar (InSAR) and global positioning systems (GPS). Qu et al. [2015] used ERS, Envisat, and ALOS-1 to characterize subsidence in HG from 1995 to 2011, but a five-year gap in InSAR measurements exists due to a lack of freely available SAR data. We build upon the previous study by comparing subsidence patterns detected by Sentinel-1 data starting in July 2015. We used GMT5SAR to generate a stack of interferograms with perpendicular baselines less than 100 meters and temporal baselines less than 100 days to minimize temporal and spatial decorrelation. We applied the short baseline subset (SBAS) time series processing using GIAnT and compared our results with GPS measurements. The implications of this work will strengthen land subsidence monitoring systems in HG and broadly aid in the development of effective water resource management policies and strategies.

  20. Satellite SAR interferometric observations of displacements associated with urban subsidence in Suzhou, Eastern China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    SAR interferometry (InSAR) has a high potential for surface displacement mapping in the range from millimeter to meter. In this paper the potential of ERS-1/2 SAR interferometry for mapping subtle land subsidence has been investigated. A time series of ERS-1/2 SAR data from February 1993 to February 2000 is collected from measurements taken in Suzhou city, Jiangsu Province, China, eight ERS-1/2 SAR images are used to create seven interferograms, and three differential interferograms are produced using the three-pass method, which clearly show the spatial extent of land subsidence. The deformation maps are validated by leveling surveys, the correlation coefficient and standard deviation between them are 0.943 and 0.1706 respectively. Based on seven benchmarks, the subsidence rates are estimated, the overall trends are in close agreement with InSAR results. The results of study show that for the mapping of land subsidence in urban environments InSAR has a strong potential due to its cost-saving, high resolution and accuracy.

  1. Land subsidence induced by groundwater extraction and building damage level assessment-a case study of Datun,China

    Institute of Scientific and Technical Information of China (English)

    FENG Qi-yan; LIU Gang-jun; MENG Lei; FU Er-jiang; ZHANG Hai-rong; ZHANG Ke-fei

    2008-01-01

    As in many parts of the world, long-term excessive extraction of groundwater has caused significant land-surface subsidence in the residential areas of Datun coal mining district in East China. The recorded maximum level of subsidence in the area since 1976 to 2006 is 863 mm, and the area with an accumulative subsidence more than 200 mm has reached 33.1 km2 by the end of 2006. Over ten cases of building crack due to ground subsidence have already been observed. Spatial variation in ground subsidence often leads to a corresponding pattern of ground deformation. Buildings and underground infrastructures have been under a higher risk of damage in locations with greater differential ground deformation. Governmental guideline in China classifies building damages into four different levels, based on the observable measures such as the width of wall crack, the degree of door and window deformation, the degree of wall inclination and the degree of structural destruction. Building damage level (BDL) is estimated by means of ground deformation analysis in terms of variations in slope gradient and curvature. Ground deformation analysis in terms of variations in slope gradient has shown that the areas of BDL Ⅲ and BDL Ⅱ sites account for about 0.013 km2 and 0.284km2 respectively in 2006, and the predicted areas of BDL (define this first) Ⅲ and Ⅱ sites will be about 0.029 km2 and 0.423 km2respectively by 2010. The situation is getting worse as subsidence continues. That calls for effective strategies for subsidence mitigation and damage reduction, in terms of sustainable groundwater extraction, enhanced monitoring and the establishment of early warning systems.

  2. Surface water waves due to an oscillatory wavemaker in the presence of surface tension

    Directory of Open Access Journals (Sweden)

    B. N. Mandal

    1992-01-01

    Full Text Available The initial value problem of generation of surface water waves by a harmonically oscillating plane vertical wavemaker in an infinite incompressible fluid under the action of gravity and surface tension is investigated. In the asymptotic evaluation of the free surface depression for large time and distance, the contribution to the integral by stationary phase method gives rise to transient component of the free surface depression while the contribution from the poles give rise to steady state component. It is observed that the presence of surface tension sometimes changes the qualitative nature of the transient component of free surface depression.

  3. Subsidence and Deforestation: Implications for Flooding in Delta’s Southeast and East Asia

    Directory of Open Access Journals (Sweden)

    . Nurhamidah

    2011-01-01

    Full Text Available Delta is a low-lying area which can be found at the mouth of a river. Nowadays, concentration of flooding occurs in many deltaic areas due to combination of several factors. Meanwhile, a big number of people live on flood plain of main rivers and river deltas which will be threatened by flooding.  Land subsidence and deforestation are two phenomena which had been occurring very high until recently in SEE Asia region. Increasing of population strongly influences the natural hydrological processes. Due to pressure for land, substantial areas of peat swamps in SEE Asia have been presently are being reclaimed for agriculture or for other land use. In natural conditions swamp areas functioned as a retention area by adsorbing flood water, thereby preventing or mitigation flooding in downstream areas. But unfortunately, large areas of the original forests in large peat swamp forests have disappeared due to human activities such as illegal logging and fires. In other side increasing population, industries, agricultures and plantations will increase water demand. Activities of ground water extraction will be increasing as well. It can cause land subsidence and furthermore tide can easily propagate into deltaic areas moreover compounded by lowering of land surface due to land subsidence. Since flooding is an issue has been identified then these two phenomena need to be identified as well.

  4. Monitoring Land Subsidence over Mining Areas with Sentinel-1 Differential SAR Interferometry

    Science.gov (United States)

    Mirek, Katarzna

    2016-08-01

    This paper presents possibilities for monitoring man- made surface deformation on example of two areas (Fig. 1): Upper Silesian Coal Basin and Lubelskie Coal Basin (Poland). Synthetic Aperture Radar (SAR) images acquired by Sentinel-1A satellite are utilized in subsidence studies. Satellite radar interferometry technique (InSAR) was used to detecting and monitoring subsidence. There are clearly visible on obtained interferograms subsidence troughs as a distinctive concentric fringes. This study is a part of initiated the SSUMMO project (Surface Subsidence Multidisciplinary Monitoring). The project will provide multidisciplinary monitoring of mining areas and it will prepare the methodology and research software for continuous observation of the impact of exploitation on surface.

  5. U.S. Geological Survey Subsidence Interest Group conference, Edwards Air Force Base, Antelope Valley, California, November 18-19, 1992; abstracts and summary

    Science.gov (United States)

    Prince, Keith R.; Galloway, Devin L.; Leake, Stanley A.

    1995-01-01

    Land subsidence, the loss of surface elevation as a result of the removal of subsurface support, affects every state in the United States. More than 17,000 mi2 of land in the United States has been lowered by the various processes that produce land subsidence with annual costs from resulting flooding and structural damage that exceed $125 million. It is estimated that an additional $400 million is spent nationwide in attempts to control subsidence. Common causes of land subsidence include the removal of oil, gas, and water from underground reservoirs; dissolution of limestone aquifers (sinkholes); underground mining activities; drainage of organic soils; and hydrocompaction (the initial wetting of dry soils). Overdrafting of aquifers is the major cause of areally extensive land subsidence, and as ground-water pumping increases, land subsidence also will increase. Land subsidence and its effects on engineering structures have been recognized for centuries, but it was not until this century that the processes that produce land subsidence were identified and understood. In 1928, while working with field data from a test of the Dakota Sandstone aquifer, O.E. Meinzer of the U.S. Geological Survey recognized the compressibility of aquifers. Around the same time, Karl Terzaghi, a soil scientist working at Harvard University, developed the one-dimensional consolidation theory that provided a quantitative means of predicting soil compaction resulting from the drainage of compressible soils. Thus, with the recognition of the compressibility of aquifers (Meinzer), and the development of a quantitative means of predicting soil compaction as a consequence of the reduction of intergranular pore pressure (Terzaghi), the theory of aquifer-system compaction was formed. With the widespread availa- bility of electric power in rural areas, and the advent of the deep turbine pump, ground-water withdrawals increased dramatically throughout the country in the 1940's and 1950's. Along

  6. Subsidence crack closure: rate, magnitude and sequence

    Energy Technology Data Exchange (ETDEWEB)

    De Graff, J.V.; Romesburg, H.C.

    1981-06-01

    Tension cracks are a major surface disturbance resulting from subsidence and differential settlement above underground coal mines. Recent engineering studies of subsidence indicate that cracks may close where tensile stresses causing the cracks are reduced or relaxed. This stress reduction occurs as mining in the area is completed. Crack closure was confirmed by a study in the Wasatch Plateau coal field of central Utah. Cracks occurred in both exposed bedrock and regolith in an area with maximum subsidence of 3 m. Mean closure rate was 0.3 cm per week with individual crack closure rates between 0.2 cm and 1.0 cm per week. The mean crack closure magnitude was 80% with closure magnitudes varying between 31% and 100%. Actual magnitude values ranged from 0.6 cm to 6.5 cm with a mean value of 3.8 cm. Statistical analysis compared width change status among cracks over time. It was found that: 1) a 41% probability existed that a crack would exhibit decreasing width per weekly measurement, 2) closure state sequences seem random over time, and 3) real differences in closure state sequence existed among different cracks. (6 refs.) (In English)

  7. Instruments for subsurface monitoring of geothermal subsidence

    Energy Technology Data Exchange (ETDEWEB)

    O' Rourke, J.E.; Ranson, B.B.

    1979-07-01

    The requirements for a subsurface geothermal subsidence instrument were reviewed. Available instruments for monitoring subsurface displacements, both vertical and horizontal, were studied and the most capable instruments identified. Techniques and materials for improving existing or developing new instruments were evaluated. Elements of sensor and signal technology with potential for high temperature monitoring of subsidence were identified. Drawing from these studies, methods to adapt production wells for monitoring were proposed and several new instrumentation systems were conceptually designed. Finally, four instrumentation systems were selected for future development. These systems are: triple sensor induction sensor probe (with casing collar markers); triple sensor gamma ray detector probe (with radioactive markers); triple sensor reed switch probe (with magnet markers); and triple sensor oscillator-type magnet detector probe (with magnet markers). All are designed for use in well casing incorporating slip couplings or bellows sections, although the gamma ray detector probe may also be used in unlined holes. These systems all measure vertical moement. Instruments to measure horizontal displacement due to geothermal subsidence were studied and the required instrument performance was judged to be beyond the state-of-the-art. Thus, no conceptual designs for instruments to monitor horizontal movement are included.

  8. Spatial Analysis of Soil Subsidence in Peat Meadow Areas in Friesland in Relation to Land and Water Management, Climate Change, and Adaptation

    Science.gov (United States)

    Brouns, Karlijn; Eikelboom, Tessa; Jansen, Peter C.; Janssen, Ron; Kwakernaak, Cees; van den Akker, Jan J. H.; Verhoeven, Jos T. A.

    2015-02-01

    Dutch peatlands have been subsiding due to peat decomposition, shrinkage and compression, since their reclamation in the 11th century. Currently, subsidence amounts to 1-2 cm/year. Water management in these areas is complex and costly, greenhouse gases are being emitted, and surface water quality is relatively poor. Regional and local authorities and landowners responsible for peatland management have recognized these problems. In addition, the Netherlands Royal Meteorological Institute predicts higher temperatures and drier summers, which both are expected to enhance peat decomposition. Stakeholder workshops have been organized in three case study areas in the province of Friesland to exchange knowledge on subsidence and explore future subsidence rates and the effects of land use and management changes on subsidence rates. Subsidence rates were up to 3 cm/year in deeply drained parcels and increased when we included climate change in the modeling exercises. This means that the relatively thin peat layers in this province (ca 1 m) would shrink or even disappear by the end of the century when current practices continue. Adaptation measures were explored, such as extensive dairy farming and the production of new crops in wetter conditions, but little experience has been gained on best practices. The workshops have resulted in useful exchange of ideas on possible measures and their consequences for land use and water management in the three case study areas. The province and the regional water board will use the results to develop land use and water management policies for the next decades.

  9. Spatial analysis of soil subsidence in peat meadow areas in Friesland in relation to land and water management, climate change, and adaptation.

    Science.gov (United States)

    Brouns, Karlijn; Eikelboom, Tessa; Jansen, Peter C; Janssen, Ron; Kwakernaak, Cees; van den Akker, Jan J H; Verhoeven, Jos T A

    2015-02-01

    Dutch peatlands have been subsiding due to peat decomposition, shrinkage and compression, since their reclamation in the 11th century. Currently, subsidence amounts to 1-2 cm/year. Water management in these areas is complex and costly, greenhouse gases are being emitted, and surface water quality is relatively poor. Regional and local authorities and landowners responsible for peatland management have recognized these problems. In addition, the Netherlands Royal Meteorological Institute predicts higher temperatures and drier summers, which both are expected to enhance peat decomposition. Stakeholder workshops have been organized in three case study areas in the province of Friesland to exchange knowledge on subsidence and explore future subsidence rates and the effects of land use and management changes on subsidence rates. Subsidence rates were up to 3 cm/year in deeply drained parcels and increased when we included climate change in the modeling exercises. This means that the relatively thin peat layers in this province (ca 1 m) would shrink or even disappear by the end of the century when current practices continue. Adaptation measures were explored, such as extensive dairy farming and the production of new crops in wetter conditions, but little experience has been gained on best practices. The workshops have resulted in useful exchange of ideas on possible measures and their consequences for land use and water management in the three case study areas. The province and the regional water board will use the results to develop land use and water management policies for the next decades.

  10. How a Curvilinear Continental Margin Influences Its Subsidence History

    Science.gov (United States)

    Sacek, V.; Ussami, N.

    2012-12-01

    Current one-dimensional (1D) and two-dimensional (2D) thermo-mechanical models successfully explain the first-order vertical motions of sedimentary basins created by lithospheric extension. However, the modeling of second-order effects such as extra-subsidence, non-monotonic-subsidence or protracted-subsidence still remains controversial. One aspect that has not been fully considered in the current models is that the rifting direction leading to the continental break-up does not always follow a straight line, which demands a three-dimensional (3D) approach. The aim of this work is to demonstrate the importance of using a 3D model that takes into account the curvature of rifting along the margin and theoretically predicts some of the second-order subsidence observations. Our results indicate that concave oceanward margins tend to subside faster than convex ones. This differential subsidence of the margin is a result of the combined effect of lateral thermal conduction, small-scale mantle (or edge driven) convection and the curvature of the rifting. We have used the finite element code CITCOM (Moresi & Gurnis, 1996; Zhong et al., 2000) to construct 3D numerical models of the mantle convection and its effect on the surface evolution. We observed that the differential subsidence along a curved margin is dependent on the viscosity structure of the mantle: for an asthenospheric viscosity of 5×1020 Pa.s the differential subsidence can reach more than 700 m assuming a sediment filled basin; however, for low asthenospheric viscosity (geometry. As an application of this 3D conceptual model for curved margin, we analysed the stratigraphic evolution of the Santos Basin, offshore Southeastern Brazil, and we propose that the variations in the subsidence history along the margin can be explained by its 3D geometry and the dynamical evolution of the mantle. We conclude that the incorporation of the third dimension in the study of the subsidence history of divergent margins may

  11. Damping of an ion acoustic surface wave due to surface currents

    CERN Document Server

    Lee, H J

    1999-01-01

    The well-known linear dispersion relation for an ion acoustic surface wave has been obtained by including the linear surface current density J sub z parallel to the interface and by neglecting the linear surface current density J sub x perpendicular to the interface. The neglect of J sub x is questionable although it leads to the popular boundary condition that the tangential electric field is continuous. In this work, linear dispersion relation for an ion acoustic surface wave is worked out by including both components of the linear current density J . When that is done, the ion acoustic wave turns out to be heavily damped. If the electron mass is taken to be zero (electrons are Bolzmann-distributed), the perpendicular component of the surface current density vanishes, and we have the well-known ion acoustic surface wave eigenmode. We conclude that an ion acoustic surface wave propagates as an eigenmode only when its phase velocity is much smaller than the electron thermal velocity.

  12. Effect of the surface geology on strong ground motions due to the 2016 Central Tottori Earthquake, Japan

    Science.gov (United States)

    Kagawa, Takao; Noguchi, Tatsuya; Yoshida, Shohei; Yamamoto, Shinji

    2017-08-01

    On October 21, 2016, an earthquake with Japan Meteorological Agency (JMA) magnitude 6.6 hit the central part of Tottori Prefecture, Japan. This paper demonstrates two notable effects of the surface geology on strong ground motions due to the earthquake. One is a predominant period issue observed over a large area. A seismic intensity of 6 lower on the JMA scale was registered at three sites in the disaster area. However, the peak ground acceleration ranged from 0.3 to 1.4 G at the three sites because of the varying peak periods of observed strong ground motions. The spectral properties of the observations also reflect the damage around the sites. Three-component microtremors were observed in the area; the predominant ground period distributions based on horizontal to vertical spectral ratios were provided by the authors. The peak periods of the strong motion records agree well with predominant periods estimated from microtremor observations at a rather hard site; however, the predominant periods of the microtremors are slightly shorter than those of the main shock at the other two soft sites. We checked the nonlinear effect at the sites by comparing the site responses to small events and the main shock. The peak periods of the main shock were longer than those of the weak motions at the sites. This phenomenon indicates a nonlinear site effect due to large ground motions caused by the main shock. A horizontal component of the accelerogram showed rather pulsating swings that indicate cyclic mobility behavior, especially at a site close to a pond shore; ground subsidence of 20 cm was observed around the site. The peak periods of weak motions agree well with those of the microtremor observations. This implies an important issue that the predominant periods estimated by microtremors are not sufficient to estimate the effect of surface geology for disaster mitigation. We have to estimate the predominant periods under large ground motions considering the nonlinear site

  13. Modeling of time dependent subsidence for coal and ore deposits

    Institute of Scientific and Technical Information of China (English)

    Ryszard Hejmanowski

    2015-01-01

    Coal and ore underground mining generates subsidence and deformation of the land surface. Those defor-mations may cause damage to buildings and infrastructures. The environmental impact of subsidence will not be accepted in the future by the society in many countries. Especially there, where the mining regions are densely urbanized, the acceptance of the ground deformations decreases every year. The only solution is to limit the subsidence or its impact on the infrastructure. The first is not rentable for the mining industry, the second depends on the precise subsidence prediction and good preventing management involved in the mining areas. The precision of the subsidence prediction depends strictly on the mathematical model of the deformation phenomenon and on the uncertainty of the input data. The subsidence prediction in the geological conditions of the raw materials used to be made on the basis of numerical modeling or the stochastic models. A modified solution of the stochastic model by Knothe will be presented in the paper. The author focuses on the precise description of the deposit shape and on the time dependent displacements of the rock mass. A two parameters’ time function has been introduced in the algorithm.

  14. Cone Penetration Testing, a new approach to quantify coastal-deltaic land subsidence by peat consolidation

    Science.gov (United States)

    Koster, Kay; Erkens, Gilles; Zwanenburg, Cor

    2016-04-01

    It is undisputed that land subsidence threatens coastal-deltaic lowlands all over the world. Any loss of elevation (on top of sea level rise) increases flood risk in these lowlands, and differential subsidence may cause damage to infrastructure and constructions. Many of these settings embed substantial amounts of peat, which is, due to its mechanically weak organic composition, one of the main drivers of subsidence. Peat is very susceptible to volume reduction by loading and drainage induced consolidation, which dissipates pore water, resulting in a tighter packing of the organic components. Often, the current state of consolidation of peat embedded within coastal-deltaic subsidence hotspots (e.g. Venice lagoon, Mississippi delta, San Joaquin delta, Kalimantan peatlands), is somewhere between its initial (natural) and maximum compressed stage. Quantifying the current state regarding peat volume loss, is of utmost importance to predict potential (near) future subsidence when draining or loading an area. The processes of subsidence often afflict large areas (>103 km2), thus demanding large datasets to assess the current state of the subsurface. In contrast to data describing the vertical motions of the actual surface (geodesy, satellite imagery), subsurface information applicable for subsidence analysis are often lacking in subsiding deltas. This calls for new initiatives to bridge that gap. Here we introduce Cone Penetration Testing (CPT) to quantify the amount of volume loss peat layers embedded within the Holland coastal plain (the Netherlands) experienced. CPT measures soil mechanical strength, and hundreds of thousands of CPTs are conducted each year on all continents. We analyzed 28 coupled CPT-borehole observations, and found strong empirical relations between volume loss and increased peat mechanical strength. The peat lost between ~20 - 95% of its initial thickness by dissipation of excess pore water. An increase in 0.1 - 0.4 MPa of peat strength is

  15. Land subsidence along the Delta-Mendota Canal in the northern part of the San Joaquin Valley, California, 2003-10

    Science.gov (United States)

    Sneed, Michelle; Brandt, Justin; Solt, Mike

    2013-01-01

    ; even during record-setting precipitation years, such as 2010–11, water deliveries have fallen short of requests and groundwater pumping was required to meet the irrigation demand. Due to the expected continued demand for irrigation supply water and the limitations and uncertainty of surface-water supplies, groundwater pumping and associated land subsidence is likely to continue in the future. Spatially detailed information on land subsidence is needed to facilitate minimization of future subsidence-related damages to the Delta-Mendota Canal and other infrastructure in the San Joaquin Valley. The integration of subsidence, deformation, and water-level measurements—particularly continuous measurements—enables the analysis of aquifer-system response to increased groundwater pumping, which in turn, enables identification of the preconsolidation head and calculation of aquifer-system storage properties. This information can be used to improve numerical model simulations of groundwater flow and aquifer-system compaction and allow for consideration of land subsidence in the evaluation of water-resource management alternatives.

  16. Subsidence prediction in Estonia's oil shale mines

    Energy Technology Data Exchange (ETDEWEB)

    Pastarus, J.R. [Tallinn Technical University, Tallinn (Estonia); Toomik, A. [Institute of Ecology, Johvi (Estonia)

    2000-07-01

    This paper analysis the stability of the mining blocks in Estonian oil shale mines, where the room-and-pillar mining system is used. The pillars are arranged in a singular grid. The oil shale bed is embedded at the depth of 40-75 m. The processes in overburden rocks and pillars have caused the subsidence of the ground surface. The conditional thickness and sliding rectangle methods performed calculations. The results are presented by conditional thickness contours. Error does not exceed 4%. Model allows determining the parameters of spontaneous collapse of the pillars and surface subsidence. The surface subsidence parameters will be determined by conventional calculation scheme. Proposed method suits for stability analysis, failure prognosis and monitoring. 8 refs.

  17. Development of TDR distributed sensors for land subsidence measurement

    Science.gov (United States)

    Chung, Chih-Chung; Lin, Chih-Ping

    2016-04-01

    The influences subjected by land subsidence and notably inundation are raising in Taiwan recently. To efficiently access the problems, historical trends and the instant field measurement data (at least by days), including multi-depth subsidence leveling and water leveling, are essential and urgent. However, current multi-depth subsidence leveling with magnetic rings conducted by manual operating, for example, lacks high temporal and spatial resolution data, which cannot evaluate the consistency between the subsidence leveling and the limited underground water levels in the same aquifer layer appropriately. To improve the field measurements, this study is carried out based on the core technology of Time Domain Reflectometry (TDR). In the preliminary idea, TDR distributed sensors, as magnetic rings for land subsidence measurements in a borehole, are developed with the underground water level sensors embedded. The prototypes of TDR distributed sensors indicates the feasibility of measuring, but the influence of signal dissipating due to the long transmission line (>100 m) need to be brought attention to, as well as the corresponding measurement accuracy. Therefore, a laboratorial physical modeling is suggested for further evaluation, and this modeling is constructed now. All the measurement data are expected to be employed and fed back as the calibrators and indicators to propose the defense strategy for land subsidence and inundation.

  18. Monitoring subsidence with InSAR and inference of groundwater change

    Science.gov (United States)

    Farr, T. G.

    2014-12-01

    Groundwater use is increasing in many parts of the world due to population pressure and reduced availability of surface water and rainfall. California's Central Valley and southern Arizona in particular have experienced subsidence in many groundwater basins in recent years due to groundwater overdraft. In order to make informed decisions for adaptation, water resource managers need to know the extent of groundwater depletion, both spatially and volumetrically, and to be able to monitor it over long periods. Water wells provide one solution, but owing to remoteness, funding limitations, a lack of wells, and the difficulty of mandating government monitoring of private wells, less direct methods are necessary. Mapping and monitoring subsidence and rebound from orbit with interferometric synthetic aperture radar (InSAR) may provide important indicators of groundwater state and dynamics for water resource managers as well as warnings of potential damage to infrastructure. We are working with water resource managers at the California Department of Water Resources to produce and update maps of subsidence 'hot-spots' where subsidence threatens to cause irreversible aquifer compaction and loss of groundwater storage capacity. In the future, Germany's TerraSAR-X, Italy's Cosmo SkyMed, Japan's PALSAR-2, Europe's Sentinels, and NASA's NISAR offer the promise of extending the time series of observations and expanding this capability to regions of the world with no effective means to monitor the state of their groundwater. This would provide societal benefits to large segments of the global population dependent on groundwater to bridge gaps in surface and rain water supply. As Earth's climate changes, monitoring of this critical resource will help reduce conflicts over water. * Work performed under contract to NASA

  19. Land subsidence and problems affecting land use at Edwards Air Force Base and vicinity, California, 1990

    Science.gov (United States)

    Blodgett, James C.; Williams, J. S.

    Land subsidence in Antelope Valley, which includes Edwards Air Force Base, was first reported in the 1950's; by 1967, about 200 square miles of Antelope Valley were affected by as much as 2 feet of subsidence. The purpose of the report is to present the results to date of recent studies done by the U.S. Geological Survey, in cooperation with the U.S. Department of the Air Force, to determine the cause and areal extent of land subsidence and surface deformation on Rogers Lakebed and vicinity, and the effects of surface deformation on runways used for aircraft landings at Edwards AFB in southern California. Because of the time-related effects of land subsidence, several years of data collection will be needed to establish subsidence trends and evaluate those factors causing land subsidence.

  20. Quality factor due to roughness scattering of shear horizontal surface acoustic waves in nanoresonators

    NARCIS (Netherlands)

    Palasantzas, G.

    2008-01-01

    In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to late

  1. Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

    Directory of Open Access Journals (Sweden)

    Jesús Pacheco-Martínez

    2015-12-01

    Full Text Available In this work we present an application of InSAR and gravimetric surveys for risk management related to land subsidence and surface ground faulting generation. A subsidence velocity map derived from the 2007–2011 ALOS SAR imagery and a sediment thicknesses map obtained from the inversion of gravimetric data were integrated with a surface fault map to produce a subsidence hazard zoning in the city of Aguascalientes, Mexico. The resulting zoning is presented together with specific recommendations about geotechnical studies needed for further evaluation of surface faulting in these hazard zones. The derived zoning map consists in four zones including null hazard (stable terrain without subsidence, low hazard (areas prone to subsidence, medium hazard (zones with subsidence and high hazard (zones with surface faulting. InSAR results displayed subsidence LOS velocities up to 10 cm/year and two subsidence areas unknown before this study. Gravimetric results revealed that the thicker sediment sequence is located toward north of Aguascalientes City reaching up to 600 m in thickness, which correspond to a high subsidence LOS velocity zone (up to 6 cm/year.

  2. Monitoring delta subsidence with Interferometric Synthetic Aperture Radar (InSAR)

    Science.gov (United States)

    Higgins, S.; Overeem, I.; Syvitski, J. P.

    2014-12-01

    Can subsidence in river deltas be monitored in near real-time at the spatial and temporal resolution needed for informing critical management decisions? Interferometric Synthetic Radar Aperture (InSAR) is a satellite-based technique that can map ground deformation with millimeter-scale vertical resolution over thousands of square kilometers. InSAR has enormous potential to shed light on the dynamics of actively subsiding deltas, but the technique is not commonly applied outside of major cities due to the difficulty of performing InSAR in wet, vegetated settings. Given these limitations, how can InSAR best serve the global effort to monitor sinking deltas? Here, an overview of InSAR processing is provided that addresses delta-specific challenges, including frequent cloud-cover in tropical areas; noisy signals in wetlands and flooded fields; dense forests that interact unpredictably with different radar wavelengths; flat landscapes that hinder image stacking algorithms; rapid urban development that can render Digital Elevation Models (DEMs) inaccurate; and a lack of in situ GPS (Global Positioning System) receivers for InSAR calibration. InSAR has unique value for monitoring subsidence in deltas, and some natural and anthropogenic drivers of subsidence can be resolved by InSAR. High-resolution InSAR measurements from the Ganges-Brahmaputra Delta (GBD) are then presented and validated against GPS data. Surface motion is shown to reflect subsurface stratigraphy, and sediment compaction is shown to be the most important factor in this delta on short (non-tectonic) timescales. Average compaction rates throughout the eastern delta range from 0 to > 18 mm/y, varying by more than an order of magnitude depending on the ages and grain sizes of surface and subsurface sediment layers. Fastest subsidence is observed in Holocene organic-rich mud, and slowest subsidence is observed along the Meghna River and in areas with surface or subsurface sand deposits. Although groundwater

  3. Hurricane Katrina sediment slowed elevation loss in subsiding brackish marshes of the Mississippi River delta

    Science.gov (United States)

    McKee, K.L.; Cherry, J.A.

    2009-01-01

    Although hurricanes can damage or destroy coastal wetlands, they may play a beneficial role in reinvigorating marshes by delivering sediments that raise soil elevations and stimulate organic matter production. Hurricane Katrina altered elevation dynamics of two subsiding brackish marshes in the Mississippi River deltaic plain by adding 3 to 8 cm of sediment to the soil surface in August 2005. Soil elevations at both sites subsequently declined due to continued subsidence, but net elevation gain was still positive at both Pearl River (+1.7 cm) and Big Branch (+0.7 cm) marshes two years after the hurricane. At Big Branch where storm sediments had higher organic matter and water contents, post-storm elevation loss was more rapid due to initial compaction of the storm layer in combination with root-zone collapse. In contrast, elevation loss was slower at Pearl River where the storm deposit (high sand content) did not compact and the root zone did not collapse. Vegetation at both sites fully recovered within one year, and accumulation of root matter at Big Branch increased 10-fold from 2005 to 2006, suggesting that the hurricane stimulated belowground productivity. Results of this study imply that hurricane sediment may benefit subsiding marshes by slowing elevation loss. However, long-term effects of hurricane sediment on elevation dynamics will depend not only on the amount of sediment deposited, but on sediment texture and resistance to compaction as well as on changes in organic matter accumulation in the years following the hurricane.

  4. Environmental Investigation and Evaluation of Land Subsidence in the Datong Coalfield Based on InSAR Technology

    Institute of Scientific and Technical Information of China (English)

    JIA Xiuming; MA Chao; ZHAO Anyuan

    2008-01-01

    Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak.Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR (synthetic aperture radar interferometry) and D-InSAR(differential synthetic aperture radar interferometry), supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmentai background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made: (1) the multi-temporal SAR magnitude images were used to interpret the geological structure, vegetation, micro-geomorphology and drainage system; (2) the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and (3) the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas (sites). In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas (sites) were obtained, belonging to those in 1993-1996, 1996-1997, 1997-1998,1998-2001, 1998--2002 and 2001-2003 respectively. Of the

  5. Measuring Spatiotemporal Features of Land Subsidence, Groundwater Drawdown, and Compressible Layer Thickness in Beijing Plain, China

    Directory of Open Access Journals (Sweden)

    Yongyong Li

    2017-01-01

    Full Text Available Beijing is located on multiple alluvial-pluvial fans with thick Quaternary unconsolidated sediments. It has suffered serious groundwater drawdown and land subsidence due to groundwater exploitation. This study aimed to introduce geographical distribution measure methods into land subsidence research characterizing, geographically, land subsidence, groundwater drawdown, and compressible layer thickness. Therefore, we used gravity center analysis and standard deviational ellipse (SDE methods in GIS to statistically analyze their concentration tendency, principle orientation, dispersion trend, and distribution differences in 1995 (1999, 2007, 2009, 2011, and 2013. Results show that they were all concentrated in Chaoyang District of Urban Beijing. The concentration trend of land subsidence was consistent with that of groundwater drawdown. The principle orientation of land subsidence was SW–NE, which was more similar with that of the static spatial distribution of the compressible layer. The dispersion tendency of land subsidence got closer to that of the compressible layer with its increasing intensity. The spatial distribution difference between land subsidence and groundwater drawdown was about 0.2, and that between land subsidence and compressible layer thickness it decreased from 0.22 to 0.07, reflecting that the spatial distribution pattern of land subsidence was increasingly close to that of the compressible layer. Results of this study are useful for assessing the distribution of land subsidence development and managing groundwater resources.

  6. A Picture of Subsidized Households 2009

    Data.gov (United States)

    Department of Housing and Urban Development — Picture of Subsidized Households describes the nearly 5 million households living in HUD-subsidized housing in the United States for the year 2009. Picture 2009...

  7. A Picture of Subsidized Housholds 2008

    Data.gov (United States)

    Department of Housing and Urban Development — Picture of Subsidized Households describes the nearly 5 million households living in HUD-subsidized housing in the United States for the year 2008. Picture 2008...

  8. Comparison of water-level, extensometric, DInSAR and simulation data for quantification of subsidence in Murcia City (SE Spain)

    Science.gov (United States)

    Tessitore, S.; Fernández-Merodo, J. A.; Herrera, G.; Tomás, R.; Ramondini, M.; Sanabria, M.; Duro, J.; Mulas, J.; Calcaterra, D.

    2016-05-01

    Subsidence due to groundwater overexploitation has been recognized in the metropolitan area of Murcia (25 km2) in south-eastern Spain since the early 1990s. Previous published works have focused their attention on land subsidence that occurred during the drought period between 1995 and 2008. This work first analyzes the groundwater recovery that has occurred since 2008 and then determines the kind of associated ground deformation detected by the new extensometric data. Subsequently, subsidence time series are computed on 24 geotechnical boreholes scattered throughout the study area by means of a hydro-mechanical finite element code and a linear-elastic constitutive law. A spatio-temporal interpolation of the numerically modeled surface displacements is performed over the whole domain and compared with extensometers and DInSAR-derived displacement maps in two different periods: the drought period from 2004 to 2008, and the recovery period from 2008 to 2012. In spite of the limited information on the geomechanical parameters characterizing the modelled geological formations, the proposed approach is able to discriminate areas where the soils have an elastic behavior (small differences in the comparisons) or an elasto-plastic behavior (large differences in the comparisons). This zonation enhances the understanding of the subsidence phenomenon in Murcia City and could prevent, from a quantitatively point of view, future severe subsidence due to aquifer overexploitation.

  9. INTERNAL STRUCTURE OF ASTEROIDS HAVING SURFACE SHEDDING DUE TO ROTATIONAL INSTABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Hirabayashi, Masatoshi [Research Associate, Colorado Center for Astrodynamics Research, Aerospace Engineering Sciences, University of Colorado Boulder (United States); Sánchez, Diego Paul [Senior Research Associate, Colorado Center for Astrodynamics Research, Aerospace Engineering Sciences, University of Colorado Boulder (United States); Scheeres, Daniel J., E-mail: masatoshi.hirabayashi@colorado.edu [Richard Seebass Chair, Professor, Colorado Center for Astrodynamics Research, Aerospace Engineering Sciences, University of Colorado Boulder (United States)

    2015-07-20

    Surface shedding of an asteroid is a failure mode where surface materials fly off due to strong centrifugal forces beyond the critical spin period, while the internal structure does not deform significantly. This paper proposes a possible structure of an asteroid interior that leads to surface shedding due to rapid rotation rates. A rubble pile asteroid is modeled as a spheroid composed of a surface shell and a concentric internal core, the entire assembly called the test body. The test body is assumed to be uniformly rotating around a constant rotation axis. We also assume that while the bulk density and the friction angle are constant, the cohesion of the surface shell is different from that of the internal core. First, developing an analytical model based on limit analysis, we provide the upper and lower bounds for the actual surface shedding condition. Second, we use a Soft-sphere Discrete Element Method (SSDEM) to study dynamical deformation of the test body due to a quasi-static spin-up. In this paper we show the consistency of both approaches. Additionally, the SSDEM simulations show that the initial failure always occurs locally and not globally. In addition, as the core becomes larger, the size of lofted components becomes smaller. These results imply that if there is a strong core in a progenitor body, surface shedding is the most likely failure mode.

  10. Investigating the Impacts of Surface Temperature Anomalies Due to Wildfires in Northern Sub-Saharan Africa

    Science.gov (United States)

    Gabbert, T.; Ichoku, C. M.; Matsui, T.; Capehart, W. J.

    2014-12-01

    The northern Sub-Saharan African region (NSSA) is an area of intense study due to the recent severe droughts that have dire consequences on the population, which relies mostly on rainfed agriculture for its food supply. This region's weather and hydrologic cycle are very complex and are dependent on the West African Monsoon. Different regional processes affect the West African Monsoon cycle and variability. One of the areas of current investigation is the water cycle response to the variability of land surface characteristics. Land surface characteristics are often altered in NSSA due to agricultural practices, grazing, and the fires that occur during the dry season. To better understand the effects of biomass burning on the hydrologic cycle of the sub-Saharan environment, an interdisciplinary team sponsored by NASA is analyzing potential feedback mechanisms due to the fires. As part of this research, this study focuses on the effects of land surface changes, particularly albedo and skin temperature, that are influenced by biomass burning. Surface temperature anomalies can influence the initiation of convective rainfall and surface albedo is linked to the absorption of solar radiation. To capture the effects of fire perturbations on the land surface, NASA's Unified Weather and Research Forecasting (NU-WRF) model coupled with NASA's Land Information System (LIS) is being used to simulate some of the fire-induced surface temperature anomalies and other environmental processes. In this presentation, we will report the strategy for these simulations, and show some preliminary results.

  11. Variation in surface fractal of graphite due to the adsorption of polyoxyethylene sorbitan monooleate

    Energy Technology Data Exchange (ETDEWEB)

    Hou Qingfeng [Research Center of Surface and Interface Chemical Engineering Technology, Nanjing University, 22 Hankou Road, Nanjing 210093 (China); Lu Xiancai [State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093 (China); Liu Xiandong [State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093 (China); Hu Baixing [Research Center of Surface and Interface Chemical Engineering Technology, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)]. E-mail: houqingfeng@nju.org.cn; Lu Zhijun [State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093 (China); Shen Jian [Research Center of Surface and Interface Chemical Engineering Technology, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)

    2005-02-15

    The fractal analysis is carried out to study the influence of adsorption of polyoxyethylene sorbitan monooleate (Tween 80) on the surface properties of graphite. The surface fractal dimension (dSF), BET surface area (SBET) and pore size distribution (PSD) are calculated from low temperature nitrogen adsorption isotherms. The decline in the dSF of graphite surface is found as the adsorption amount of Tween 80 increases, which suggests that the adsorbed Tween 80 smoothes the graphite surface. Additionally, the observation of atomic force microscopy (AFM) proves that the original slit pores in pure graphite are blocked up and the step defect sites are screened by Tween 80, which may result in the reduction of graphite roughness. The PSD pattern of graphite changes after the adsorption due to the pore blocking effect. SBET of the graphite decreases as the adsorption amount of Tween 80 increases, which is attributed to both pore blocking effect and surface screening effect.

  12. Surface and Internal Waves due to a Moving Load on a Very Large Floating Structure

    Directory of Open Access Journals (Sweden)

    Taro Kakinuma

    2012-01-01

    Full Text Available Interaction of surface/internal water waves with a floating platform is discussed with nonlinearity of fluid motion and flexibility of oscillating structure. The set of governing equations based on a variational principle is applied to a one- or two-layer fluid interacting with a horizontally very large and elastic thin plate floating on the water surface. Calculation results of surface displacements are compared with the existing experimental data, where a tsunami, in terms of a solitary wave, propagates across one-layer water with a floating thin plate. We also simulate surface and internal waves due to a point load, such as an airplane, moving on a very large floating structure in shallow water. The wave height of the surface or internal mode is amplified when the velocity of moving point load is equal to the surface- or internal-mode celerity, respectively.

  13. NUMERICAL ANALYSIS OF SATURATED-UNSATURATED SEEPAGE FLOW IN FRACTURED ROCK MASS DUE TO SURFACE INFILTRATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Seepage flow in fractured rock mass due to surface infiltration is a saturated-unsaturated seepage process. Aimed at rock mass with large fracture density, which can be equivalent to continuum, a mathematical model for saturated-unsaturated seepage flow in fractured rock mass due to surface infiltration was established in this paper. The Galerkin finite element method was used in numerical simulation and a finite element program used to calculate saturated-unsaturated seepage flow due to surface infiltration was worked out. A model experiment was employed examine the reasonableness of the program. The results show that the proposed model and program are reasonable. The application of the analysis method in this paper in an engineering project shows that the method is reliable and feasible.

  14. Land subsidence of coastal areas of Jiangsu Province, China: historical review and present situation

    Directory of Open Access Journals (Sweden)

    J. Q. Zhu

    2015-11-01

    Full Text Available Surface faults related to land subsidence have been observed in coastal cities, such as Nantong, Yancheng, and Lian Yungang, in Jiangsu Province (CAJS since the early 1970s. Nowadays, increases flooding and rising sea levels are attributed to subsidence caused by groundwater pumping. In this work we present a brief description of land subsidence in CAJS, we examine the mechanisms of land subsidence induced mainly by groundwater pumping and its evolution and economic implications as well as the implemented measures by the local government to prevent new damage.

  15. Land subsidence risk assessment and protection in mined-out regions

    Directory of Open Access Journals (Sweden)

    A. Zhao

    2015-11-01

    Full Text Available Land subsidence due to underground mining is an important hazard that causes large damages and threatens to social and economic activities. The China government has started a national project to estimate the risk of land subsidence in the main coal production provinces, such as Heilongjiang, Anhui and Shanxi Provinces. Herein, the investigation methods for land subsidence identification were reported, some types of land settlement are summarized, and some successful engineering measures to mitigate the subsidence are discussed. A Geographical Information System (GIS for land subsidence risk assessment is developed and is based on site investigations and numerrical simulation of the subsidence process. In this system, maps of mining intensity and risk ranks are developed.

  16. Internal Structure of Asteroids Having Surface Shedding due to Rotational Instability

    CERN Document Server

    Hirabayashi, Masatoshi; Scheeres, Daniel J

    2015-01-01

    Surface shedding of an asteroid is a failure mode where surface materials fly off due to strong centrifugal forces beyond the critical spin period, while the internal structure does not deform significantly. This paper proposes a possible structure of an asteroid interior that leads to such surface shedding due to rapid rotation rates. A rubble pile asteroid is modeled as a spheroid composed of a surface shell and a concentric internal core, the entire assembly called the test body. The test body is assumed to be uniformly rotating around a constant rotation axis. We also assume that while the bulk density and the friction angle are constant, the cohesion of the surface shell is different from that of the internal core. First, developing an analytical model based on limit analysis, we provide the upper and lower bounds for the actual surface shedding condition. Second, we use a Soft-Sphere Discrete Element Method (SSDEM) to study dynamical deformation of the test body due to a quasi-static spin-up. In this pa...

  17. 浅埋暗挖地铁隧道施工地表沉降规律分析%Analysis of surface subsidence rule of shallow subway tunnel construction

    Institute of Scientific and Technical Information of China (English)

    李金奎; 王飞飞; 白会人

    2012-01-01

    为了研究大连地铁202标段促进路站—春光街站暗挖区间人工素填土地段单双线隧道施工地表沉降规律,通过现场实测和数据分析整理的方法,在地铁隧道开挖期间建立了地表沉降监控量测测站,运用精密水准仪进行3个月的监测,监测结果表明浅埋暗挖隧道在开挖期间地表沉降最大位置处于隧道中心线的正上方,沉降量约为25.66~31.82 mm.提出了距跨比β的概念,距跨比β的有效工程取值范围-4<β<4,地表沉降与距跨比β密切相关,其中-2<β<2地表沉降剧烈阶段,约占整体变形的67.5~77.6%,沉降速率约达0.84~0.93 mm/d.建议应加强监测频率,增加现场巡视.现场测试结果与文克尔地表沉降计算模型相吻合,监测成果对大连地铁及类似的浅埋暗挖隧道建设有借鉴作用.%To study the Dalian Metro section 202 ' s (Cujin Road station-Chunguang Street station, which is shallowly buried and covered with plain fill ) ground surface settlement, the monitoring measuring station was built during the construction. After 3 months' measuring by precision level, the data shows that the maximum point is in the center line of the tunnel of the upper part, the settlement is about 25. 66 — 31.82 mm. We put forward the concept of the distance span ratio β, β effective value range was - 4 <β< 4, surface subsidence was closely related with β, severe surface subsidence stage was —2 <(3< 2, which accounted for 67. 5 — 77. 6% of the whole deformation ,and settlement rate was about 0. 84 — 0. 93 mm/d. So the monitoring frequency and site tour should be strengthened. The result of field test is consistent with that of the ground surface settlement calculation model . The monitoring results have reference for Dalian subway and the similar shallow depth excavation tunnel construction.

  18. Do hospitals cross-subsidize?

    Science.gov (United States)

    David, Guy; Lindrooth, Richard C; Helmchen, Lorens A; Burns, Lawton R

    2014-09-01

    Despite its salience as a regulatory tool to ensure the delivery of unprofitable medical services, cross-subsidization of services within hospital systems has been notoriously difficult to detect and quantify. We use repeated shocks to a profitable service in the market for hospital-based medical care to test for cross-subsidization of unprofitable services. Using patient-level data from general short-term hospitals in Arizona and Colorado before and after entry by cardiac specialty hospitals, we study how incumbent hospitals adjusted their provision of three uncontested services that are widely considered to be unprofitable. We estimate that the hospitals most exposed to entry reduced their provision of psychiatric, substance-abuse, and trauma care services at a rate of about one uncontested-service admission for every four cardiac admissions they stood to lose. Although entry by single-specialty hospitals may adversely affect the provision of unprofitable uncontested services, these findings warrant further evaluation of service-line cross-subsidization as a means to finance them.

  19. An analysis on the relationship between land subsidence and floods at the Kujukuri Plain in Chiba Prefecture, Japan

    Science.gov (United States)

    Ito, Y.; Chen, H.; Sawamukai, M.; Su, T.; Tokunaga, T.

    2015-11-01

    Surface environments at the Kujukuri Plain in Chiba Prefecture, Japan, in 1970, 2004, and 2013, were analyzed and compared to discuss the possible impact of land subsidence on the occurrence of floods. The study area has been suffered from land subsidence due to ground deformation from paleo-earthquakes, tectonic activities, and human-induced subsidence by groundwater exploitation. Meteorological data, geomorphological data including DEM obtained from the airborne laser scanning (1-m spatial resolution), leveling data, and the result of our assessment map (Chen et al., 2015) were used in this study. Clear relationship between floods and land subsidence was not recognized, while geomorphological setting, urbanization, and change of precipitation pattern were found to contribute to the floods. The flood prone-area is distributed on the characteristic geomorphological setting such as floodplain and back swamp. It was revealed that the urban area has been expanded on these geomorphological setting in recent years. The frequency of hourly precipitation was also shown to be increased in the past ca. 40 years, and this could induce rapid freshet and overflow of small- and medium-sized rivers and sewerage lines. The distribution of depression areas was increased from 2004 to 2013. This change could be associated with the ground deformation after the Tohoku earthquake (Mw = 9.0) in 2011.

  20. Limitations of Heat Conductivity in Cryogenic Sensors Due to Surface Roughness

    NARCIS (Netherlands)

    Moktadir, Z.; Bruijn, M.P.; Wiegerink, Remco J.; Elwenspoek, Michael Curt; Ridder, M.; Mels, W.A.

    2002-01-01

    The limitation of heat conductivity in cryogenic sensors due to surface roughness was discussed. It was found that at macroscopic scale and high temperatures, the transport coefficients were characteristic properties of the material and were independent of the shape and size of specimen. An

  1. Dynamic subsidence basins in coal mines based on rock mass theological theory

    Institute of Scientific and Technical Information of China (English)

    Yang Yu; Gong Zhiqiang; Liang Bing

    2011-01-01

    In order to investigate the surface deformation caused by coal mining and to reduce environmental damage,more accurate information of dynamic subsidence basins,caused by coal mining,is needed.Based on rheological theory,we discuss surface deformation mechanism of dynamic subsidence on the assumption that both the roof and the coal seam are visco-elastic media,put forward the idea that the principle of surface deformation is similar to that of roofs,except for their parameters.Therefore,a surface deformation equation can be obtained,given the equation of the roof deformation derived.from using a HM rheological model.In the end,we apply the equation of surface deformation as a practical subsidence prediction in a coal mine.Given the rheologic properties of a rock mass,the results of our research of a dynamic subsidence basin can predict the development of surface deformation as a function of time.which is more important than the ultimate subsidence itself.The results indicate that using rheological theory to calculate the deformation of a dynamic subsidence basin is suitable and provides some reference for surface deformation of dynamic subsidence basins.

  2. Mapping Land Subsidence Related to Underground Coal Fires in the Wuda Coalfield (Northern China Using a Small Stack of ALOS PALSAR Differential Interferograms

    Directory of Open Access Journals (Sweden)

    Delu Pan

    2013-03-01

    Full Text Available Coal fires have been found to be a serious problem worldwide in coal mining reserves. Coal fires burn valuable coal reserves and lead to severe environmental degradation of the region. Moreover, coal fires can result in massive surface displacements due to the reduction in volume of the burning coal and can cause thermal effects in the adjacent rock mass particularly cracks and fissures. The Wuda coalfield in Northern China is known for being an exclusive storehouse of prime coking coal as well as for being the site of occurrence of the maximum number of known coal fires among all the coalfields in China and worldwide, and is chosen as our study area. In this study, we have investigated the capabilities and limitations of ALOS PALSAR data for monitoring the land subsidence that accompanies coal fires by means of satellite differential interferometric synthetic aperture radar (DInSAR observations. An approach to map the large and highly non-linear subsidence based on a small number of SAR images was applied to the Wuda coalfield to reveal the spatial and temporal signals of land subsidence in areas affected by coal fires. The DInSAR results agree well with coal fire data obtained from field investigations and thermal anomaly information, which demonstrates that the capability of ALOS PALSAR data and the proposed approach have remarkable potential to detect this land subsidence of interest. In addition, our results also provide a spatial extent and temporal evolution of the land subsidence behavior accompanying the coal fires, which indicated that several coal fire zones suffer accelerated ongoing land subsidence, whilst other coal fire zones are newly subsiding areas arising from coal fires in the period of development.

  3. MECHANISM OF WATER-SOIL COUPLED ACTION DURING MINING SUBSIDENCE

    Institute of Scientific and Technical Information of China (English)

    狄乾生; 黄山民

    1991-01-01

    This paper,on the basis ot the scientific research of engineering geological exploration in a mining area ,systematically studies the reasons and influence factors of consolidation and deformation of the saturated soil included in the thick loose water-bearing overburden due to mining subsidence ,and analyses the dissipation of hyperstatic pore water pressure during the change of original stress and strain state of, the soil. Again,by means of the coupled model based on Cambridge model and Biot's three-dimensional consolidation theory,adopting a great many physico-mechanical parameters measured in various soil layers,the paper analyses the consolidation and deformation of saturated soil affected by mining subsidence with elasto-plastic finite element method. Thus ,the research not only reveals the regulation of stress ,straln,displacement and hyperstatic pore water pressure dissipation in overlying soil mass,but also opens up a new direction and way for the research of mining subsidence.

  4. Image current heating on a metal surface due to charged bunches

    Directory of Open Access Journals (Sweden)

    Xintian E. Lin

    2000-10-01

    Full Text Available When charged particles pass through a metal pipe, they are accompanied by an image current on the metal surface. With intense short bunches passing near or even into the metal surface, the peak image current density can be very high. This current may result in substantial temperature rise on the surface, especially in high peak current, multibunch operation. In this paper, we derive an explicit formula for the surface temperature rise due to this previously unrecognized pulsed heating effect and show that this effect dominates the proposed linear coherent light source collimator spoiler and wire scanner heating. Without proper account, it can result in component and instrument failures. The result also applies to optical transition radiation screens, profile screens, wire scanners, exit windows, and targets, which the beam crosses.

  5. Imaging Land Subsidence Induced by Groundwater Extraction in Beijing (China Using Satellite Radar Interferometry

    Directory of Open Access Journals (Sweden)

    Mi Chen

    2016-06-01

    Full Text Available Beijing is one of the most water-stressed cities in the world. Due to over-exploitation of groundwater, the Beijing region has been suffering from land subsidence since 1935. In this study, the Small Baseline InSAR technique has been employed to process Envisat ASAR images acquired between 2003 and 2010 and TerraSAR-X stripmap images collected from 2010 to 2011 to investigate land subsidence in the Beijing region. The maximum subsidence is seen in the eastern part of Beijing with a rate greater than 100 mm/year. Comparisons between InSAR and GPS derived subsidence rates show an RMS difference of 2.94 mm/year with a mean of 2.41 ± 1.84 mm/year. In addition, a high correlation was observed between InSAR subsidence rate maps derived from two different datasets (i.e., Envisat and TerraSAR-X. These demonstrate once again that InSAR is a powerful tool for monitoring land subsidence. InSAR derived subsidence rate maps have allowed for a comprehensive spatio-temporal analysis to identify the main triggering factors of land subsidence. Some interesting relationships in terms of land subsidence were found with groundwater level, active faults, accumulated soft soil thickness and different aquifer types. Furthermore, a relationship with the distances to pumping wells was also recognized in this work.

  6. Accumulation of microswimmers near surface due to steric confinement and rotational Brownian motion

    Science.gov (United States)

    Li, Guanglai; Tang, Jay

    2009-03-01

    Microscopic swimmers display some intriguing features dictated by Brownian motion, low Reynolds number fluid mechanics, and boundary confinement. We re-examine the reported accumulation of swimming bacteria or bull spermatozoa near the boundaries of a fluid chamber, and propose a kinematic model to explain how collision with surface, confinement and rotational Brownian motion give rise to the accumulation of micro-swimmers near a surface. In this model, an elongated microswimmer invariably travels parallel to the surface after hitting it from any incident angle. It then takes off and swims away from the surface after some time due to rotational Brownian motion. Based on this analysis, we obtain through computer simulation steady state density distributions that reproduce the ones measured for the small bacteria E coli and Caulobacter crescentus, as well as for the much larger bull spermatozoa swimming near surfaces. These results suggest strongly that Brownian dynamics and surface confinement are the dominant factors for the accumulation of microswimmers near a surface.

  7. Surface damage of metallic implants due to mechanical loading and chemical reactions

    Science.gov (United States)

    Ryu, Jaejoong

    The present study investigates interfacial damage mechanism of modular implants due to synergetic action of mechanical contact loading and corrosion. Modular implants are manufactured such that surfaces have a characteristic degree of roughness determined by tool tip size and motion of tool path or feeding speed. The central hypothesis for this work is that during contact loading of metallic implants, mechanisms of damage and dissolution are determined by contact loads, plastic deformation, residual stresses and environmental conditions at the nanoscale surface asperities; while during subsequent rest periods, mechanism of metallic dissolution is determined by the environmental conditions and residual stress field induced due to long range elastic interactions of the plastically deformed asperities. First part of the thesis is focused on investigating the mechanisms underlying surface roughness evolution due to stress-assisted dissolution during the rest period. The latter part is focused on investigating material removal mechanisms during single asperity contact of implant surfaces. Experimental study was performed to elucidate the roughness evolution mechanism by combined effect of multi-asperity contact and environmental corrosion. Cobalt-chromium-molybdenum specimen was subjected to either contact loading alone or alternating contact loading and exposure to reactive environment. Roughness of the specimen surface was monitored by optical profilometry and Fast Fourier Transform (FFT) calculation was used to characterize the evolving behavior of roughness modes. Finite element analysis (FEA) was employed to identify influences of surface morphological configurations and contact pressures on the residual stress development. Analytical model of multi-asperity contact has been developed for prediction of residual stress field for different roughness configurations during varying magnitude of contact loads based on elastic inclusion theory. Experimental results

  8. Impact of halite dissolution subsidence on Quaternary fluvial terrace development: Case study of the Huerva River, Ebro Basin, NE Spain

    Science.gov (United States)

    Guerrero, Jesús; Gutiérrez, Francisco; Lucha, Pedro

    2008-08-01

    calibre of the channel gravels) indicate a change in the channel pattern from braided to meandering due to the lowering of the valley slope in the reach affected by subsidence. Some of the anomalous features of the lower terraces (T8 to T12) attributable to dissolution subsidence include: (1) steepening of the T8 terrace profile; (2) change of the T10 terrace from degradational to aggradational downstream Cuarte; and (3) thickening recorded beneath the T11 terrace surface.

  9. Tectonic subsidence of the Sirte Basin, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Gumati, Y.D.; Nairn, A.E.M. (South Carolina Univ., Columbia, SC (US). Earth Sciences and Resources Inst.)

    1991-01-01

    The Sirte Basin of Libya has a history of faulting and differential subsidence brought about by lithospheric extension during a 25 MM (million) year period beginning in the Late Cretaceous. The first phase of extension and initial subsidence, with faulting and graben formation, occurred from Cenomanian to Campanian times. Following extension, there occurred widespread thermally-driven subsidence from Maastrichtian through Eocene and Oligocene times, accounting for about half of the total subsidence. Details of basin subsidence, sediment accumulation rates and facies variations have been reconstructed for the northern Sirte Basin from a suite of approximately 100 completion well logs and numerous seismic lines. These show that at various times in the late Cretaceous and Paleocene-Eocene, renewed differential subsidence followed fault reactivation. Tectonic subsidence maps show a systematic SE to NW shift in the loci of maximum and minimum subsidence, which parallels the structural trend of the basin. The greatest subsidence observed in the Sirte Trough is 2,085 meters, whereas subsidence of the horsts is generally less than 1,000 meters. The stretching factor ({beta}: in the range of 1.1 to 1.75), corresponds to an extension of 10-75%, with an average of less than 50%. The greatest stretching is associated with the central graben. (Author).

  10. Reliability Based assessment of buildings under earthquakes due to gas extraction

    NARCIS (Netherlands)

    Steenbergen, R.D.J.M.; Vrouwenvelder, A.C.W.M.

    2014-01-01

    In the northern part of the Netherlands over de last decades shallow earthquakes are induced due to large scale gas extraction from the Groningen gas field. Earthquakes occur due to the compaction of the reservoir rock, which leads to subsidence at surface and strain build-up in the reservoir rock

  11. Reliability Based assessment of buildings under earthquakes due to gas extraction

    NARCIS (Netherlands)

    Steenbergen, R.D.J.M.; Vrouwenvelder, A.C.W.M.

    2014-01-01

    In the northern part of the Netherlands over de last decades shallow earthquakes are induced due to large scale gas extraction from the Groningen gas field. Earthquakes occur due to the compaction of the reservoir rock, which leads to subsidence at surface and strain build-up in the reservoir rock a

  12. Analysis of surface degradation of high density polyethylene (HDPE) insulation material due to tracking

    Indian Academy of Sciences (India)

    R Sarathi; S Chandrasekar; V Sabari Giri; C Venkataseshaiah; R Velmurugan

    2004-06-01

    In the present work, tracking phenomena has been studied with HDPE material under a.c. voltage, with ammonium chloride as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The diffusion coefficient of the material was obtained. The thermal and chemical stability of the material were identified by carrying out a methodical experimental study. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), were carried out and it was concluded that the mechanism of tracking process is due to the surface degradation. The surface condition of the insulation structure was characterized for any surface discharges or tracking, using the leakage current measurement, utilizing the wavelet concepts.

  13. Flooding hazards from sea extremes and subsidence

    DEFF Research Database (Denmark)

    Sørensen, Carlo; Vognsen, Karsten; Broge, Niels

    2015-01-01

    If we do not understand the effects of climate change and sea level rise (SLR) we cannot live in low-lying coastal areas in the future. Permanent inundation may become a prevalent issue but more often floods related to extreme events have the largest damage potential, and the management of flooding...... hazards needs to integrate the water loading from various sources. Furthermore, local subsidence must be accounted for in order to evaluate current and future flooding hazards and management options. We present the methodology (Figure) and preliminary results from the research project “Coastal Flooding...... Hazards due to Storm Surges and Subsidence” (2014-2017) with the objective to develop and test a practice oriented methodology for combining extreme water level statistics and land movement in coastal flooding hazard mapping and in climate change adaptation schemes in Denmark. From extreme value analysis...

  14. September 2016 Bayou Choctaw Subsidence Report

    Energy Technology Data Exchange (ETDEWEB)

    Moriarty, Dylan Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lord, Anna C. Snider [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Subsidence monitoring is a crucial component to understanding cavern integrity of salt storage caverns. This report looks at historical and current data at the Bayou Choctaw Strategic Petroleum Reserve Site. Data from the most recent land-based annual surveys, GPS, and tiltmeter indicate the subsidence rates across the site are approximately 0.0 ft./yr. Because of this, there is no evidence from the subsidence survey to suggest any of the DOE caverns have been structurally compromised.

  15. Land Subsidence Monitoring Using PS-InSAR Technique for L-Band SAR Data

    Science.gov (United States)

    Thapa, S.; Chatterjee, R. S.; Singh, K. B.; Kumar, D.

    2016-10-01

    Differential SAR-Interferometry (D-InSAR) is one of the potential source to measure land surface motion induced due to underground coal mining. However, this technique has many limitation such as atmospheric in homogeneities, spatial de-correlation, and temporal decorrelation. Persistent Scatterer Interferometry synthetic aperture radar (PS-InSAR) belongs to a family of time series InSAR technique, which utilizes the properties of some of the stable natural and anthropogenic targets which remain coherent over long time period. In this study PS-InSAR technique has been used to monitor land subsidence over selected location of Jharia Coal field which has been correlated with the ground levelling measurement. This time series deformation observed using PS InSAR helped us to understand the nature of the ground surface deformation due to underground mining activity.

  16. Prediction of land subsidence caused by groundwater exploitation in Hanoi, Vietnam, using multifactorial correlation analysis

    Institute of Scientific and Technical Information of China (English)

    Thinh Hong Phi; Ludmila Aleksandrovna Strokova

    2013-01-01

    Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation. This article introduces and applies the method to establish the function of the surface settlement rate (Vs) and the function of the time-dependent surface settlement (St) caused by groundwater exploitation, based on data acquired at three land subsidence monitoring stations in the Hanoi area of Vietnam. Comparison with actual monitoring data indicates that the prediction results are relatively close to the monitoring data. From this, we conclude that multifactorial correlation analysis is a reliable method and can be used to predict future land subsidence caused by groundwater exploitation in Hanoi.

  17. Groundwater Regulation in the Houston-Galveston Region to Control Subsidence - Balancing Total Water Demand, Available Alternative Water Supplies, and Groundwater Withdrawal

    Science.gov (United States)

    Turco, M. J.

    2014-12-01

    In 1975, as a result of area residents and local governments becoming increasingly alarmed by the continued impact of subsidence on economic growth and quality of life in the region, the Harris-Galveston Coastal Subsidence District was created by the 64th Texas Legislature as an underground water conservation district. The primary mission of what is now the Harris-Galveston Subsidence District, is to provide for the regulation of the withdrawal of groundwater to control subsidence. Subsidence has been a concern in the Houston, TX area throughout most of recent history. Since 1906, over 10 feet of subsidence has occurred, with a broad area of 6 feet of subsidence throughout most of the Houston Area.Over its nearly forty years of existence, the District has developed substantial data sets providing the foundation for its regulatory plan. Annual water-level measurements, a network of deep extensometers, over 80 subsidence GPS monitors, and updated numerical and analytical models have been utilized. Periodically, the District utilizes U.S. Census data to predict the future magnitude and location of population and water demand. In 2013, all of these data sets were combined producing an updated regulatory plan outlining the timelines of conversion to alternative sources of water and defining the maximum percentage groundwater can contribute to a user's total water demand.The management of the groundwater resources within the District has involved significant coordination with regional ground and surface water suppliers; ongoing interaction with other state and local regulatory bodies; analysis of accurate and up to date predictions on water usage; the enforcement of real disincentives to those who rely too heavily on groundwater and a commitment to practicing and promoting water conservation.Water supplies in the region are projected to continue to be stressed in the future due to rapid population increases in the region. Future District efforts will be focused on

  18. Land Subsidence and Groundwater Resources Investigations with the Use of D-InSAR, Numerical Modeling, and Field Data in the Toluca Valley, Mexico

    Science.gov (United States)

    Calderhead, A. I.; Martel, R.; Rivera, A.; Garfias, J.; Therrien, R.

    2008-12-01

    In the Toluca Valley, Mexico, urban and industrial growth have resulted in groundwater pumping exceeding recharge. Currently, there is a significant water budget deficit within the basin primarily due to groundwater pumping, and the loss is increasing with time. The stresses on the aquifer have caused significant changes on the water flow patterns, a reversal in the direction of hydraulic gradients, the disappearance of artesian springs and wetlands and noticeable land subsidence within the basin. The focus of this study is the investigation of water resources and land subsidence with the use of Differential Synthetic Aperture Radar Interferometry (D-InSAR), numerical modeling, and field data. The study is divided into two parts: 1) investigation of groundwater depletion in the Toluca Valley; and 2) assessment of land subsidence in the Toluca Valley. A spatially variable recharge model based on the Hydrologic Evaluation of Landfill Performance (HELP) numerical model examines the recharge; pumping estimates are based on a recent census and differences in piezometric surfaces. Currently there is a net loss (recharge - pumping) of over 150 million cubic meters per year of groundwater within the Toluca Basin aquifers. We examine various changes in regional flow patterns, and groundwater levels decline throughout the valley. At the current rate of consumption, groundwater resources are not sustainable for the population of the valley. Directly related to the decrease in groundwater levels is the occurrence of land subsidence. Regional land subsidence of the Toluca Valley is observed with the use of SAR images obtained from the European Space agency's ERS-1, ERS-2 and ENVISAT Satellites and the Canadian Space Agency's RADARSAT-1 satellite. Data from years 1996 to 2008 are used to locate and quantify the subsidence; with subsidence rates reaching more than 15 cm/year. Results from the different sensors are also compared. The findings are verified with in

  19. Unsteady Free-surface Waves Due to a Submerged Body in Two-dimensional Oseen Flows

    Institute of Scientific and Technical Information of China (English)

    LUDong-qiang; AllenT.CHWANG

    2004-01-01

    The two-dimensional unsteady free-surface waves due to a submerged body moving in an incompressible viscous fluid of infinite depth is considered.The disturbed flow is governed by the unsteadyOseen equations with the kinematic and dynamic boundary conditions linearized for the free-surface waves.Accordingly, the body is mathematically simulated by an Oseenlet with a periodically oscillating strength.By means of Fourier transforms,the exact solution for the free-surface waves is expressed by an integral with a complex dispersion function, which explicitly shows that the wave dynamics is characterized by a Reynolds number and a Strouhal number.By applying Lighthill's theorem, asymptotic representations are derived for the far-field waves with a sub-critical and a super-critical Strouhal number. It is found that the generated waves due to the oscillating Oseenlet consist of the steady-state and transient responses. For the viscous flow with a sub-critical Strouhal number, there exist four waves: three propagate downstream while one propagates upstream.However, for the viscous flow with a super-critical Strouhal number, there exist two waves only,which propagate downstream.

  20. Recent land subsidence caused by the rapid urban development in the Hanoi urban region (Vietnam using ALOS InSAR data

    Directory of Open Access Journals (Sweden)

    V. K. Dang

    2013-11-01

    Full Text Available Since the 1990s the land subsidence due to the rapid urbanization has been considered a severely destructive hazard in the center of Hanoi City. Although previous studies and measurements have quantified the subsiding deformation in Hanoi center, no data exist for the newly established districts in the south and the west, where construction development has been most significant and where groundwater pumping has been very intensive over the last decade. With a multi-temporal InSAR approach, we quantify the spatial distribution of the land subsidence in the whole Hanoi urban region using ALOS images over the 2007–2011 period. The map of the mean subsidence velocity reveals that the northern bank of the Red River appears stable, whereas some areas in southern bank are subsiding with a mean vertical rate up to 68 mm yr−1, especially within the three new urban districts of Hoang Mai, Ha Dong and Hoai Duc. We interpret the spatial distribution of the surface deformation as the combination of the nature of the unsaturated layer, the lowering of groundwater in the aquifers due to pumping withdrawal capacity, the increase of built-up surfaces and the type of building foundation. The time evolution deduced from the InSAR time series is consistent with previous leveling data and shows that the lowering rate of the surface slightly decreases till 2008. Then, a seasonal variation suggests that the deformation became non-stationary, with upward and downward transient displacements related to the charge and discharge of the aquifer following the changes between rainy and dry seasons.

  1. Land subsidence in major cities of Central Mexico: Interpreting InSAR-derived land subsidence mapping with hydrogeological data

    Science.gov (United States)

    Castellazzi, Pascal; Arroyo-Domínguez, Norma; Martel, Richard; Calderhead, Angus I.; Normand, Jonathan C. L.; Gárfias, Jaime; Rivera, Alfonso

    2016-05-01

    Significant structural damages to urban infrastructures caused by compaction of over-exploited aquifers are an important problem in Central Mexico. While the case of Mexico City has been well-documented, insight into land subsidence problems in other cities of Central Mexico is still limited. Among the cities concerned, we present and discuss the cases of five of them, located within the Trans-Mexican Volcanic Belt (TMVB): Toluca, Celaya, Aguascalientes, Morelia, and Queretaro. Applying the SBAS-InSAR method to C-Band RADARSAT-2 data, five high resolution ground motion time-series were produced to monitor the spatio-temporal variations of displacements and fracturing from 2012 to 2014. The study presents recent changes of land subsidence rates along with concordant geological and water data. It aims to provide suggestions to mitigate future damages to infrastructure and to assist in groundwater resources management. Aguascalientes, Celaya, Morelia and Queretaro (respectively in order of decreasing subsidence rates) are typical cases of fault-limited land subsidence of Central Mexico. It occurs as a result of groundwater over-exploitation in lacustrine and alluvial deposits covering highly variable bedrock topography, typical of horst-graben geological settings. Aguascalientes and Toluca show high rates of land subsidence (up to 10 cm/yr), while Celaya and Morelia show lower rates (from 2 to 5 cm/yr). Comparing these results with previous studies, it is inferred that the spatial patterns of land subsidence have changed in the city of Toluca. This change appears to be mainly controlled by the spatial heterogeneity of compressible sediments since no noticeable change occurred in groundwater extraction and related drawdown rates. While land subsidence of up to 8 cm/yr has been reported in the Queretaro Valley before 2011, rates inferior to 1 cm/yr are measured in 2013-2014. The subsidence has been almost entirely mitigated by major changes in the water management

  2. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China.

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C K; Galloway, Devin L; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-06-21

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992-2015 show time-varying trends with respect to displacement over time in California's San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr(-1) with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr(-1). Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr(-1) and cumulative subsidence as much as 155 cm.

  3. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C.K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-01-01

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and ice sheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm/yr with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm/yr. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm/yr and cumulative subsidence as much as 155 cm.

  4. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-06-01

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr‑1 with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr‑1. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr‑1 and cumulative subsidence as much as 155 cm.

  5. Increased dose near the skin due to electromagnetic surface beacon transponder.

    Science.gov (United States)

    Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

    2015-05-08

    The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women.

  6. UNSTEADY WAVES DUE TO AN IMPULSIVE OSEENLET BENEATH THE CAPILLARY SURFACE OF A VISCOUS FLUID

    Institute of Scientific and Technical Information of China (English)

    LU Dong-qiang; CHEN Xiao-bo

    2008-01-01

    The two-dimensional free-surface waves due to a point force steadily moving beneath the capillary surface of an incompressible viscous fluid of infinite depth were analytically investigated. The unsteady Oseen equations were taken as the governing equations for the viscous flows. The kinematic and dynamic conditions including the combined effects of surface tension and viscosity were linearized for small-amplitude waves on the free-surface. The point force is modeled as an impulsive Oseenlet. The complex dispersion relation for the capillary-gravity waves shows that the wave patterns are characterized by the Weber number and the Reynolds number. The asymptotic expansions for the wave profiles were explicitly derived by means of Lighthill's theorem for the Fourier transform of a function with a finite number of singularities. Furthermore, it is found that the unsteady wave system consists of four families, that is, the steady-state gravity wave, the steady-state capillary wave, the transient gravity wave, and the transient capillary wave. The effect of viscosity on the capillary-gravity was analytically expressed.

  7. Spontaneous Emulsification of a Metal Drop Immersed in Slag Due to Dephosphorization: Surface Area Quantification

    Science.gov (United States)

    Assis, Andre N.; Warnett, Jason; Spooner, Stephen; Fruehan, Richard J.; Williams, Mark A.; Sridhar, Seetharaman

    2015-04-01

    When a chemical reaction occurs between two immiscible liquids, mass transfer is continuously taking place at the liquid-liquid interface. Several studies have shown that if the species being exchanged between the two liquids are surface-active, a very pronounced decrease in interfacial tension can occur which can lead to a phenomenon called spontaneous emulsification. In steelmaking, this behavior has been observed for several reactions that involve the transfer of impurities from molten steel to a molten-oxide slag but little quantification has been made. This work focuses on spontaneous emulsification due to the dephosphorization of a Fe-P drop immersed in a basic oxygen furnace type slag. An Au-image furnace attached to a confocal scanning laser microscope was used to rapidly heat and cool the samples at different times, and X-ray computerized tomography was used to perform the surface area calculations of the samples where the slag/steel reaction was allowed to occur for distinct times. The results show that the surface area of the metal drop rapidly increases by over one order of magnitude during the first 60 seconds of the reaction while the chemical reaction is occurring at a fast rate. Once the reaction slows down, approximately after 60 seconds, the droplets start to coalesce back together minimizing the surface area and returning to a geometry close to its equilibrium shape.

  8. Land subsidence and hydrodynamic compaction of sedimentary basins

    Directory of Open Access Journals (Sweden)

    H. Kooi

    1998-01-01

    Full Text Available A one-dimensional model is used to investigate the relationship between land subsidence and compaction of basin sediments in response to sediment loading. Analysis of the model equations and numerical experiments demonstrate quasi-linear systems behaviour and show that rates of land subsidence due to compaction: (i can attain a significant fraction (>40% of the long-term sedimentation rate; (ii are hydrodynamically delayed with respect to sediment loading. The delay is controlled by a compaction response time τc that can reach values of 10-5-107 yr for thick shale sequences. Both the behaviour of single sediment layers and multiple-layer systems are analysed. Subsequently the model is applied to the coastal area of the Netherlands to illustrate that lateral variability in compaction-derived land subsidence in sedimentary basins largely reflects the spatial variability in both sediment loading and compaction response time. Typical rates of compaction-derived subsidence predicted by the model are of the order of 0.1 mm/yr but may reach values in excess of 1 mm/yr under favourable conditions.

  9. Subsidence characterization and modeling for engineered facilities in Arizona, USA

    Science.gov (United States)

    Rucker, M. L.; Fergason, K. C.; Panda, B. B.

    2015-11-01

    Several engineered facilities located on deep alluvial basins in southern Arizona, including flood retention structures (FRS) and a coal ash disposal facility, have been impacted by up to as much as 1.8 m of differential land subsidence and associated earth fissuring. Compressible basin alluvium depths are as deep as about 300 m, and historic groundwater level declines due to pumping range from 60 to more than 100 m at these facilities. Addressing earth fissure-inducing ground strain has required alluvium modulus characterization to support finite element modeling. The authors have developed Percolation Theory-based methodologies to use effective stress and generalized geo-material types to estimate alluvium modulus as a function of alluvium lithology, depth and groundwater level. Alluvial material modulus behavior may be characterized as high modulus gravel-dominated, low modulus sand-dominated, or very low modulus fines-dominated (silts and clays) alluvium. Applied at specific aquifer stress points, such as significant pumping wells, this parameter characterization and quantification facilitates subsidence magnitude modeling at its' sources. Modeled subsidence is then propagated over time across the basin from the source(s) using a time delay exponential decay function similar to the soil mechanics consolidation coefficient, only applied laterally. This approach has expanded subsidence modeling capabilities on scales of engineered facilities of less than 2 to more than 15 km.

  10. 30 CFR 817.121 - Subsidence control.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage...

  11. Variation in diffusion of gases through PDMS due to plasma surface treatment and storage conditions.

    Science.gov (United States)

    Markov, Dmitry A; Lillie, Elizabeth M; Garbett, Shawn P; McCawley, Lisa J

    2014-02-01

    Polydimethylsiloxane (PDMS) is a commonly used polymer in the fabrication of microfluidic devices due to such features as transparency, gas permeability, and ease of patterning with soft lithography. The surface characteristics of PDMS can also be easily changed with oxygen or low pressure air plasma converting it from a hydrophobic to a hydrophilic state. As part of such a transformation, surface methyl groups are removed and replaced with hydroxyl groups making the exposed surface to resemble silica, a gas impermeable substance. We have utilized Platinum(II)-tetrakis(pentaflourophenyl)porphyrin immobilized within a thin (~1.5 um thick) polystyrene matrix as an oxygen sensor, Stern-Volmer relationship, and Fick's Law of simple diffusion to measure the effects of PDMS composition, treatment, and storage on oxygen diffusion through PDMS. Results indicate that freshly oxidized PDMS showed a significantly smaller diffusion coefficient, indicating that the SiO2 layer formed on the PDMS surface created an impeding barrier. This barrier disappeared after a 3-day storage in air, but remained significant for up to 3 weeks if PDMS was maintained in contact with water. Additionally, higher density PDMS formulation (5:1 ratio) showed similar diffusion characteristics as normal (10:1 ratio) formulation, but showed 60 % smaller diffusion coefficient after plasma treatment that never recovered to pre-treatment levels even after a 3-week storage in air. Understanding how plasma surface treatments contribute to oxygen diffusion will be useful in exploiting the gas permeability of PDMS to establish defined normoxic and hypoxic oxygen conditions within microfluidic bioreactor systems.

  12. Coastal subsidence and relative sea level rise

    Science.gov (United States)

    Ingebritsen, Steven E.; Galloway, Devin L.

    2014-01-01

    Subsurface fluid-pressure declines caused by pumping of groundwater or hydrocarbons can lead to aquifer-system compaction and consequent land subsidence. This subsidence can be rapid, as much as 30 cm per year in some instances, and large, totaling more than 13 m in extreme examples. Thus anthropogenic subsidence may be the dominant contributor to relative sea-level rise in coastal environments where subsurface fluids are heavily exploited. Maximum observed rates of human-induced subsidence greatly exceed the rates of natural subsidence of unconsolidated sediments (~0.1–1 cm yr−1) and the estimated rates of ongoing global sea-level rise (~0.3 cm yr−1).

  13. Ground Surface Deformation around Tehran due to Groundwater Recharge: InSAR Monitoring.

    Science.gov (United States)

    Gourmelen, N.; Peyret, M.; Fritz, J. F.; Cherry, J.

    2003-04-01

    Tehran is located on an active tectonic and seismic zone. The surface deformation monitoring provides a powerful tool for getting a better understanding of faults kinematics and mechanisms. Used in conjunction with GPS networks, InSAR (Interferometric Synthetic Aperture Radar) provides dense and precise deformation measurements which are essential for mapping complex heterogeneous deformation fields. Moreover, urban and arid areas preserve interferometric phase coherence. The archived acquisitions of ERS that span 9 months between September 1998 and June 1999 reveal wide areas of surface uplift (by as much as 9 cm). This vertical deformation (gradual in time) has probably no tectonic meaning but is rather the ground response to ground water recharge. These zones are all located dowstream of large alluvial fans like the one of Karaj. The variation of effective stress caused by intersticial water draining could explain such surface deformation. It can also be noticed that some faults act as boundary for these deformation zones and fluid motion. The understanding of this deformation is relevant for groundwater monitoring and urban developement management. It is also necessary for discriminating it from tectonic deformation that also occurs on this zone. Due to the lack of attitude control of satellite ERS-2 since February 2001, the last images acquired could not be combined with the former acquisitions. Nevertheless, we expect to be able to enrich our set of images in order to map tectonic deformation on a longer period and to monitor in a more continuous way the deformation due to groundwater evolution. This would allow to quantify the permanent and reversible part of this signal.

  14. On the use of InSAR technology to assess land subsidence in Jakarta coastal flood plain

    Science.gov (United States)

    Koudogbo, Fifame; Duro, Javier; Garcia Robles, Javier; Arnaud, Alain; Abidin, Hasanuddin Z.

    2014-05-01

    Jakarta is the capital of Indonesia and is home to approximately 10 million people on the coast of the Java Sea. It is situated on the northern coastal alluvial plane of Java which shares boundaries with West Java Province in the south and in the east, and with Banten Province in the west. The Capital District of Jakarta (DKI) sits in the lowest lying areas of the basin. Its topography varies, with the northern part just meters above current sea level and lying on a flood plain. Subsequently, this portion of the city frequently floods. The southern part of the city is hilly. Thirteen major rivers flow through Jakarta to the Java Sea. The Ciliwung River is the most significant river and divides the city West to East. In the last three decades, urban growing of Jakarta has been very fast in sectors as industry, trade, transportation, real estate, among others. This exponential development has caused several environmental issues; land subsidence is one of them. Subsidence in Jakarta has been known since the early part of the 20th century. It is mainly due to groundwater extraction, the fast development (construction load), soil natural consolidation and tectonics. Evidence of land subsidence exists through monitoring with GPS, level surveys and InSAR investigations. InSAR states for "Interferometric Synthetic Aperture Radar". Its principle is based on comparing the distance between the satellite and the ground in consecutive satellite passes over the same area on the Earth's surface. Radar satellites images record, with very high precision, the distance travelled by the radar signal that is emitted by the satellite is registered. When this distance is compared through time, InSAR technology can provide highly accurate ground deformation measurements. ALTAMIRA INFORMATION, company specialized in ground motion monitoring, has developed GlobalSARTM, which combines several processing techniques and algorithms based on InSAR technology, to achieve ground motion

  15. Robust Design Optimization Method for Centrifugal Impellers under Surface Roughness Uncertainties Due to Blade Fouling

    Institute of Scientific and Technical Information of China (English)

    JU Yaping; ZHANG Chuhua

    2016-01-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  16. Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling

    Science.gov (United States)

    Ju, Yaping; Zhang, Chuhua

    2016-03-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  17. Structural Changes in the Surface Layer of Deep Rolled Samples Due to Thermal Loads

    Directory of Open Access Journals (Sweden)

    Strunk, R

    2017-01-01

    Full Text Available Deep rolling processes initiate plastic deformations in the surface layer. The local characteristics of deformation are dependent on the induced stress expressed by the local stress tensor. Equivalent stresses above yield strength cause plastic deformation. Additionally the intrinsic energy, e. g. the dislocation density, is enhanced and the residual stress state is changed. The effects to a deep rolled surface from an increase in temperature are mainly dependent on the material, the microstructure, the initial residual stress state, the inclusion density, the distribution of soluted alloying elements and the plastic deformation. In the described experiments the interactions between deformation and temperature of the steel grade AISI 4140 (42 CrMo 4 used for all further experiments in a transregional Collaborative Research Center (CRC were to be examined. The most simple investigation methods were chosen deliberately to allow a better statistical support of correlations between introduced strains and material reactions for a wide variation of process parameters. Since the visual effects by light microscopy in AISI 4140 were very small, the experiments were repeated with german grade 18 CrNiMo 7-6 (comparable to AISI 4820. This paper focuses on the micro structural changes in defined deep rolled surface regions due to an increase in temperature. The work described is part of the Collaborative Research Center “Process Signatures”, collaboration between Bremen University, Technical University Aachen, Germany and Oklahoma State University Stillwater, USA.

  18. Errors of five-day mean surface wind and temperature conditions due to inadequate sampling

    Science.gov (United States)

    Legler, David M.

    1991-01-01

    Surface meteorological reports of wind components, wind speed, air temperature, and sea-surface temperature from buoys located in equatorial and midlatitude regions are used in a simulation of random sampling to determine errors of the calculated means due to inadequate sampling. Subsampling the data with several different sample sizes leads to estimates of the accuracy of the subsampled means. The number N of random observations needed to compute mean winds with chosen accuracies of 0.5 (N sub 0.5) and 1.0 (N sub 1,0) m/s and mean air and sea surface temperatures with chosen accuracies of 0.1 (N sub 0.1) and 0.2 (N sub 0.2) C were calculated for each 5-day and 30-day period in the buoy datasets. Mean values of N for the various accuracies and datasets are given. A second-order polynomial relation is established between N and the variability of the data record. This relationship demonstrates that for the same accuracy, N increases as the variability of the data record increases. The relationship is also independent of the data source. Volunteer-observing ship data do not satisfy the recommended minimum number of observations for obtaining 0.5 m/s and 0.2 C accuracy for most locations. The effect of having remotely sensed data is discussed.

  19. Subsidence in the Parícutin lava field: Causes and implications for interpretation of deformation fields at volcanoes

    Science.gov (United States)

    Chaussard, Estelle

    2016-06-01

    Assessment of volcanic hazards includes interpretation of ground deformation signal, which, at polygenetic volcanoes often results from the superposition of deformation due to pressure changes in the magmatic system and due to surficial processes such as cooling of emplaced lava. The deformation signal associated with emplaced lava is sometimes considered negligible if fields are decades old, but if the lava thickness is great, deformation may still be occurring, possibly leading to misinterpretation of the observed deformation. Here I evaluate the 2007-2011 ground motion of the 1943-1952 lava field of the Parícutin monogenetic cinder cone, Mexico. Interferometric Synthetic Aperture Radar (InSAR) time series reveal patchy subsidence restricted to the lava field and following linear rates up to 5.5 cm/year. There is a clear correlation between subsidence rates and topography suggesting a causal relationship with deposits or lava thickness. I estimate these thicknesses in the subsiding areas using pre- and post-eruption topographic maps and show that they reach up to 200 m. A numerical model for lava flow cooling was developed considering radiation and convection from the surface, conductive transfer inside the flow and to the ground, and vesiculation and latent heat generation at the top and bottom of the flow. The model shows that compaction induced by cooling of the thick deposits emplaced ~ 60 years ago explains the observed subsidence when conductive transfer to the ground is considered. These results demonstrate that thick deposits can keep deforming significantly even decades after their emplacement, emphasizing the importance of considering cooling processes when interpreting deformation fields at polygenetic volcanoes producing massive lava fields.

  20. MHD Homogeneous-Heterogeneous Reactions in a Nanofluid due to a Permeable Shrinking Surface

    Directory of Open Access Journals (Sweden)

    Syahira Mansur

    2016-01-01

    Full Text Available The MHD homogeneous-heterogeneous reaction in a nanofluid flow due to a permeable shrinking surface is studied. The bvp4c program in MATLAB is used to obtain the numerical solutions for several values of parameters such as suction parameter, magnetic parameter, nanoparticle volume fraction, heterogeneous reaction and homogeneous reaction rates. The results show that dual solutions exist and the magnetic parameter and the nanoparticle volume fraction widen the range of the solution domain. Suction parameter, magnetic parameter and nanoparticle volume fraction cause the skin friction coefficient to increase and the velocity to decrease. The concentration increases as the nanoparticle volume fraction increases but decrease as the homogeneous reaction rate and heterogeneous reaction rate increase.

  1. Changes in extreme regional sea surface height due to an abrupt weakening of the Atlantic MOC

    Directory of Open Access Journals (Sweden)

    S.-E. Brunnabend

    2014-04-01

    Full Text Available As an extreme scenario of dynamical sea level changes, regional sea surface height (SSH changes that occur in the North Atlantic due to an abrupt weakening of the Atlantic Meridional Overturning Circulation (AMOC are simulated. Two versions of the same ocean-only model are used to study the effect of ocean model resolution on these SSH changes: a high-resolution (HR strongly eddying version and a low-resolution (LR version in which the effect of eddies are parameterized. The weakening of the AMOC is induced in both model versions by applying strong freshwater perturbations around Greenland. A rapid decrease of the AMOC in the HR version induces much shorter return times of several specific regional and coastal extremes in North Atlantic SSH than in the LR version. This effect is caused by a change in main eddy pathways associated with a change in separation latitude of the Gulf Stream.

  2. ANALYSIS OF HIGH FIELD NON-LINEAR LOSSES ON SRF SURFACES DUE TO SPECIFIC TOPOGRAPHIC ROUGHNESS

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xu,Charles Reece,Michael Kelley

    2012-07-01

    The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it is Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If such sites are small enough, they may produce thermally stabilized normal-conducting regions which contribute non-linear losses when viewed from the macro resonant field perspective, and thus produce degradation in Q0. We have undertaken a calculation of local surface magnetic field enhancement from specific fine topographic structure by conformal mapping method and numerically. A solution of the resulting normal conducting volume has been derived and the corresponding RF Ohmic loss simulated.

  3. Sea Level Rise and Subsidence in the Gulf of Thailand

    Science.gov (United States)

    Niemnil, Sommart

    In the Thailand -EC GEO2TECDI-SONG Project we investigate the sea level change and vertical land motion in Thailand. First, Bangkok is situated in river delta and average height is closed to sea level. Second, it is subsiding due to ground water extraction. Third, it is experiencing post-seismic motion due to nearby mega thrust earthquakes and fourth, it suffers from rising of sea levels due to global climate change. This poses a serious threat on Thai society and economy. Before mitigation methods can be devised we aim at charting, qualifying and quantifying all contributing effects by the use of satellite altimetry, GNSS, InSAR techniques and combining results with the in situ observations like tide gauge and with geophysical modeling. Adding GPS based vertical land motion to the tide gauge sea level registration reveals the absolute sea level change, which is nicely confirmed by altimetry. We find an average absolute rise of 3.5 mm/yr + 0.7, but nears mouth of Chao Praya River (Bangkok) and the Mekong delta (Ho Chi Min City), this mounts to 4 to 5 mm/yr, faster than global average. This is reinforced when accounting for the tectonic subsidence that resulted from 2004 9.1Mw Sumatra/Andaman earthquake; from 2005 onwards we find downfall in the order of 10 mm/yr. RADARSAT InSAR analyses show subsidence rates up to 25 mm/yr at many places along coastal Bangkok.

  4. Offshore gravimetric and subsidence monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Stenvold, Torkjell

    2008-06-15

    The introduction (Chapter 1) is complemented by the introductions given in Chapters 2 to 8. I am the first author of the articles in chapter 2 and 8. For the 5 articles in between I am a coauthor, and the sum of my contributions to those articles (as quantified by the respective first authors) represents about one article. Chapter 2 contains the article 'High-precision relative depth and subsidence mapping from seafloor water-pressure measurements' by Stenvold et al. (2006), published in the SPE Journal. It was submitted in March 2005, and a revised version that also contained results from the Troll 2005 survey (August) was submitted in February 2006. The method of obtaining high-precision relative depth measurements by the use of mobile pressure gauges is presented. Intra-survey and inter-survey depth repeatabilities from six surveys are presented, and the individual contributing errors are discussed and estimated. Average reservoir compressibility for the Troll field between 2002 and 2005 is obtained by matching measured subsidence with modeled subsidence. Chapter 3 contains the article 'A new seafloor gravimeter' by Sasagawa et al. (2003), published in Geophysics. It was submitted in September 2001, and a revised version was submitted in August 2002. This article describes the ROVDOG (Remotely operated Vehicledeployed Deep-Ocean Gravimeter) in detail. Gravity and pressure repeatability results from the two first Troll surveys in 1998 and 2000 are presented. Data reduction, instrumental and environmental corrections are also presented. Chapter 4 contains the article 'Precision of seafloor gravity and pressure measurements for reservoir monitoring' by Zumberge et al., and was submitted 29 February 2008 to Geophysics. This builds on the article by Sasagawa et al. (Chapter 3). Improvements and upto date intra- and inter survey repeatability results are presented. The emphasis is on gravity results since the relative depth measurements

  5. Temperature dependent surface modification of molybdenum due to low energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu [Center for Materials Under Extreme Environment (CMUXE), School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907 (United States); Novakowski, T.J.; Joseph, G. [Center for Materials Under Extreme Environment (CMUXE), School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907 (United States); Linke, J. [Forschungszentrum Jülich GmbH, EURATOM Association, Jülich D-52425 (Germany); Hassanein, A. [Center for Materials Under Extreme Environment (CMUXE), School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2015-09-15

    In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He{sup +} ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 10{sup 24} ions m{sup −2} (with a flux of 7.2 × 10{sup 20} ions m{sup −2} s{sup −1}). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823–1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO{sub 3} 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth.

  6. Subsidence Detected by Multi-Pass Differential SAR Interferometry in the Cassino Plain (Central Italy: Joint Effect of Geological and Anthropogenic Factors?

    Directory of Open Access Journals (Sweden)

    Marco Polcari

    2014-10-01

    Full Text Available In the present work, the Differential SAR Interferometry (DInSAR technique has been applied to study the surface movements affecting the sedimentary basin of Cassino municipality. Two datasets of SAR images, provided by ERS 1-2 and Envisat missions, have been acquired from 1992 to 2010. Such datasets have been processed independently each other and with different techniques nevertheless providing compatible results. DInSAR data show a subsidence rate mostly located in the northeast side of the city, with a subsidence rate decreasing from about 5–6 mm/yr in the period 1992–2000 to about 1–2 mm/yr between 2004 and 2010, highlighting a progressive reduction of the phenomenon. Based on interferometric results and geological/geotechnical observations, the explanation of the detected movements allows to confirm the anthropogenic (surface effect due to building construction and geological causes (thickness and characteristics of the compressible stratum.

  7. Wind flow modulation due to variations of the water surface roughness

    Science.gov (United States)

    Shomina, Olga; Ermakov, Stanislav; Kapustin, Ivan; Lazareva, Tatiana

    2016-04-01

    Air-ocean interaction is a classical problem in atmosphere and ocean physics, which has important geophysical applications related to calculation of vertical and horizontal humidity, aerosol and gas fluxes, development of global climate models and weather forecasts. The structure of wind flow over fixed underlying surfaces, such as forestry, buildings, mountains, is well described, while the interaction between a rough water surface and turbulent wind is far more complicated because of the presence of wind waves with different wavelength and amplitudes and propagating with different velocities and directions. The aim of this study was to investigate experimentally the variability of the wind profile structure due to variations of wave characteristics. The surface roughness variations were produced using a) surfactant films (oleic acid) spread on the water surface and b) mechanically generated waves superimposed on wind waves. The first case is related to oil slicks on sea surface, the second one - to the sea swell, which propagates into zones with lower wind velocities and interacts with wind flow. Laboratory experiments were conducted in the Oval Wind Wave Tank (OWWT) at the Institute of Applied Physics, cross-section of the wind channel is 30 cm x30 cm. Wave amplitude and the spectrum of surface waves were measured by a wire wave gauge, the wind speed was measured using a hot-wire anemometer DISA and a Pitot tube. In the experiments with surfactants, two frequencies of dripping of the oleic acid were studied, so that low concentration films with the elasticity parameters of about 19 mN/m and the high concentration ("thick") films with the elasticity of 34 mN/m were formed. In the experiments with mechanically generated waves (MGW) different regimes were studied with MGW amplitude of 3.4 mm and of 4.4 mm, and with MGW frequencies of 3.3 Hz and 3.7 Hz. It was shown, that: a) the mean velocity of the wind flow in the presence of surfactant and MGW can be described

  8. DInSAR technique: basis and applications to terrain subsidence monitoring in construction works

    OpenAIRE

    Sillerico, E.; Marchamalo, M.; Rejas, J. G.; MARTíNEZ, R

    2010-01-01

    Subsidences are defined as slow and gradual movements of the terrain or built surface. These may affect all types of terrains, and are caused by tension-induced changes for many reasons, such as lowering water tables (groundwater extraction), underground mining (minerals, coal, salt), excavation of tunnels, extraction of oil or gas, slow processes of dissolution and lixiviation of materials, consolidation of soft soils, organic soils,... The measurement and monitoring of land subsidences are ...

  9. Global sea-level rise is recognised, but flooding from anthropogenic land subsidence is ignored around northern Manila Bay, Philippines.

    Science.gov (United States)

    Rodolfo, Kelvin S; Siringan, Fernando P

    2006-03-01

    Land subsidence resulting from excessive extraction of groundwater is particularly acute in East Asian countries. Some Philippine government sectors have begun to recognise that the sea-level rise of one to three millimetres per year due to global warming is a cause of worsening floods around Manila Bay, but are oblivious to, or ignore, the principal reason: excessive groundwater extraction is lowering the land surface by several centimetres to more than a decimetre per year. Such ignorance allows the government to treat flooding as a lesser problem that can be mitigated through large infrastructural projects that are both ineffective and vulnerable to corruption. Money would be better spent on preventing the subsidence by reducing groundwater pumping and moderating population growth and land use, but these approaches are politically and psychologically unacceptable. Even if groundwater use is greatly reduced and enlightened land-use practices are initiated, natural deltaic subsidence and global sea-level rise will continue to aggravate flooding, although at substantially lower rates.

  10. Study of "3-Step Mining" Subsidence Control in Coal Mining Under Buildings

    Institute of Scientific and Technical Information of China (English)

    GUO Guang-li; ZHA Jian-feng; WU Bin; JIA Xin-guo

    2007-01-01

    Mining subsidence damage is the main factor of restricting coal mining under buildings. To control or ease effectively the degree of mining subsidence and deformation is essential to resolve this problem. Through analyzing both advantages and disadvantages of some technologies such as mining with stowing, partial extraction and grouting in separated beds of overburden, we used the principle of load replacement and propose a "3-step mining" method, a new pattern of controlling mining subsidence, which consists of: strip mining, i.e. grouting to fill and consolidate the caving zone and retained strip pillar mining. The mechanism of controlling mining subsidence by using the "3-step mining" pattern is analyzed. The effect of the control is numerically simulated. The preliminary analysis shows that the "3-step mining" can effectively control ground subsidence and deformation. By using this method, the ground subsidence factor can be controlled to a value of about 0.25. Coal recovery can reach 80%-90%. Coal mining without removing surface buildings can be realized and the economic loss resulting from ground subsidence can be greatly reduced.

  11. Study on Land Subsidence Incangzhou Area Basedon SENTINEL-1A/B Data

    Science.gov (United States)

    Zhou, H.; Wang, Y.; Yan, S.

    2017-09-01

    This paper, obtaining 39scenesof images of the Sentinel-1 A/B, monitored the Cangzhou area subsidence from Mar. 2015 to Dec. 2016 basing on using PS-InSAR technique. The annual average subsidence rate and accumulative subsidence were obtained. The results showed that the ground surface of Xian County,Cang County, Cangzhou urban area had a rebound trend; Qing County, the east of Cang County ,the west of Nanpi County and Dongguang County appeared obvious subsidence, and the accumulated subsidence in Hezhuang village of Dongguang County reached 47 mm. And from that the main reason leading to these obvious subsidence was over-exploitation of ground-water. At last, it analyzed the settlement of the High-Speed Railway (HR) which was north from the Machang town of QingCounty and south to the Lian town of Dongguang County in Cangzhou.The relative deformation of the HR between the two sections which was Lierzhuang village of Cang County and Chenxin village of Nanpi County arrived at 30 mm. Moreover, this paper discussed the application of Sentinel-1 A/B SAR images in monitoring urban land subsidence and the results provided important basic data for the relevant departments.

  12. STUDY ON LAND SUBSIDENCE INCANGZHOU AREA BASEDON SENTINEL-1A/B DATA

    Directory of Open Access Journals (Sweden)

    H. Zhou

    2017-09-01

    Full Text Available This paper, obtaining 39scenesof images of the Sentinel-1 A/B, monitored the Cangzhou area subsidence from Mar. 2015 to Dec. 2016 basing on using PS-InSAR technique. The annual average subsidence rate and accumulative subsidence were obtained. The results showed that the ground surface of Xian County,Cang County, Cangzhou urban area had a rebound trend; Qing County, the east of Cang County ,the west of Nanpi County and Dongguang County appeared obvious subsidence, and the accumulated subsidence in Hezhuang village of Dongguang County reached 47 mm. And from that the main reason leading to these obvious subsidence was over-exploitation of ground-water. At last, it analyzed the settlement of the High-Speed Railway (HR which was north from the Machang town of QingCounty and south to the Lian town of Dongguang County in Cangzhou.The relative deformation of the HR between the two sections which was Lierzhuang village of Cang County and Chenxin village of Nanpi County arrived at 30 mm. Moreover, this paper discussed the application of Sentinel-1 A/B SAR images in monitoring urban land subsidence and the results provided important basic data for the relevant departments.

  13. Simulating the hydrologic cycle in coal mining subsidence areas with a distributed hydrologic model

    Science.gov (United States)

    Wang, Jianhua; Lu, Chuiyu; Sun, Qingyan; Xiao, Weihua; Cao, Guoliang; Li, Hui; Yan, Lingjia; Zhang, Bo

    2017-01-01

    Large-scale ground subsidence caused by coal mining and subsequent water-filling leads to serious environmental problems and economic losses, especially in plains with a high phreatic water level. Clarifying the hydrologic cycle in subsidence areas has important practical value for environmental remediation, and provides a scientific basis for water resource development and utilisation of the subsidence areas. Here we present a simulation approach to describe interactions between subsidence area water (SW) and several hydrologic factors from the River-Subsidence-Groundwater Model (RSGM), which is developed based on the distributed hydrologic model. Analysis of water balance shows that the recharge of SW from groundwater only accounts for a small fraction of the total water source, due to weak groundwater flow in the plain. The interaction between SW and groundwater has an obvious annual cycle. The SW basically performs as a net source of groundwater in the wet season, and a net sink for groundwater in the dry season. The results show there is an average 905.34 million m3 per year of water available through the Huainan coal mining subsidence areas (HCMSs). If these subsidence areas can be integrated into water resource planning, the increasingly precarious water supply infrastructure will be strengthened. PMID:28106048

  14. Simulating the hydrologic cycle in coal mining subsidence areas with a distributed hydrologic model

    Science.gov (United States)

    Wang, Jianhua; Lu, Chuiyu; Sun, Qingyan; Xiao, Weihua; Cao, Guoliang; Li, Hui; Yan, Lingjia; Zhang, Bo

    2017-01-01

    Large-scale ground subsidence caused by coal mining and subsequent water-filling leads to serious environmental problems and economic losses, especially in plains with a high phreatic water level. Clarifying the hydrologic cycle in subsidence areas has important practical value for environmental remediation, and provides a scientific basis for water resource development and utilisation of the subsidence areas. Here we present a simulation approach to describe interactions between subsidence area water (SW) and several hydrologic factors from the River-Subsidence-Groundwater Model (RSGM), which is developed based on the distributed hydrologic model. Analysis of water balance shows that the recharge of SW from groundwater only accounts for a small fraction of the total water source, due to weak groundwater flow in the plain. The interaction between SW and groundwater has an obvious annual cycle. The SW basically performs as a net source of groundwater in the wet season, and a net sink for groundwater in the dry season. The results show there is an average 905.34 million m3 per year of water available through the Huainan coal mining subsidence areas (HCMSs). If these subsidence areas can be integrated into water resource planning, the increasingly precarious water supply infrastructure will be strengthened.

  15. Offshore gravimetric and subsidence monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Stenvold, Torkjell

    2008-06-15

    The introduction (Chapter 1) is complemented by the introductions given in Chapters 2 to 8. I am the first author of the articles in chapter 2 and 8. For the 5 articles in between I am a coauthor, and the sum of my contributions to those articles (as quantified by the respective first authors) represents about one article. Chapter 2 contains the article 'High-precision relative depth and subsidence mapping from seafloor water-pressure measurements' by Stenvold et al. (2006), published in the SPE Journal. It was submitted in March 2005, and a revised version that also contained results from the Troll 2005 survey (August) was submitted in February 2006. The method of obtaining high-precision relative depth measurements by the use of mobile pressure gauges is presented. Intra-survey and inter-survey depth repeatabilities from six surveys are presented, and the individual contributing errors are discussed and estimated. Average reservoir compressibility for the Troll field between 2002 and 2005 is obtained by matching measured subsidence with modeled subsidence. Chapter 3 contains the article 'A new seafloor gravimeter' by Sasagawa et al. (2003), published in Geophysics. It was submitted in September 2001, and a revised version was submitted in August 2002. This article describes the ROVDOG (Remotely operated Vehicledeployed Deep-Ocean Gravimeter) in detail. Gravity and pressure repeatability results from the two first Troll surveys in 1998 and 2000 are presented. Data reduction, instrumental and environmental corrections are also presented. Chapter 4 contains the article 'Precision of seafloor gravity and pressure measurements for reservoir monitoring' by Zumberge et al., and was submitted 29 February 2008 to Geophysics. This builds on the article by Sasagawa et al. (Chapter 3). Improvements and upto date intra- and inter survey repeatability results are presented. The emphasis is on gravity results since the relative depth measurements

  16. Polyphase basin evolution of the Vienna Basin inferred from 3D visualization of sedimentation setting and quantitative subsidence

    Science.gov (United States)

    Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

    2016-04-01

    This study analyzed and visualized data from 210 wells using a MATLAB-based program (BasinVis 1.0) for 3D visualization of sediment distribution, thickness, and quantitative subsidence of the northern and central Vienna Basin. The sedimentation settings for selected horizons were visualized to 3D sediment distribution maps, isopach maps, and cross-sections. Subsidence of the study area resulted in 3D subsidence depth and rate maps of basement and tectonic subsidences. Due to the special position of the Vienna Basin, the basin evolution was influenced by the regional tectonics of surrounding units. The 2D/3D maps provided insights into the polyphase evolution of the Vienna Basin, which is closely related to changes in the changing regional stress field and the paleoenvironmental setting. In the Early Miocene, the sedimentation and subsidence were shallow and E-W/NE-SW trending, indicating the development of piggy-back basins. During the late Early Miocene, maps show wider sedimentation and abruptly increasing subsidence by sinistral strike-slip faults, which initiated the Vienna pull-apart basin system. The sediments of the Early Miocene were supplied through a small deltaic system entering from the south. After thin sedimentation and shallow subsidence of the early Middle Miocene, the development of the Vienna Basin was controlled and accelerated mainly by NE-SW trending synsedimentary normal faults, especially the Steinberg fault. From the Middle Miocene, the subsidence was decreasing overall, however the tectonic subsidence show regionally different patterns. This study suggests that a major tensional regime change, from transtension to E-W extension, caused laterally varying subsidence across the Vienna Basin. The Late Miocene was characterized by the slowing down of basement and tectonic subsidence. From the middle Middle to Late Miocene, enormous amount of sediments supplied by a broad paleo-Danube delta complex on the western flank of the basin. The latest

  17. Study of Subsidence and Earthquake Swarms in the Western Pakistan

    Directory of Open Access Journals (Sweden)

    Jingqiu Huang

    2016-11-01

    Full Text Available In recent years, the Quetta Valley and surrounding areas have experienced unprecedented levels of subsidence, which has been attributed mainly to groundwater withdrawal. However, this region is also tectonically active and is home to several regional strike-slip faults, including the north–south striking left-lateral Chaman Fault System. Several large earthquakes have occurred recently in this area, including one deadly Mw 6.4 earthquake that struck on 28 October 2008. This study integrated Interferometric Synthetic Aperture Radar (InSAR results with GPS, gravity, seismic reflection profiles, and earthquake centroid-moment-tensor (CMT data to identify the impact of tectonic and anthropogenic processes on subsidence and earthquake patterns in this region. To detect and map the spatial-temporal features of the processes that led to the surface deformation, this study used two Synthetic Aperture Radar (SAR time series, i.e., 15 Phased Array L-band Synthetic Aperture Radar (PALSAR images acquired by an Advanced Land Observing Satellite (ALOS from 2006–2011 and 40 Environmental Satellite (ENVISAT Advanced Synthetic Aperture Radar (ASAR images spanning 2003–2010. A Small Baseline Subset (SBAS technique was used to investigate surface deformation. Five seismic lines totaling ~60 km, acquired in 2003, were used to map the blind thrust faults beneath a Quaternary alluvium layer. The median filtered SBAS-InSAR average velocity profile supports groundwater withdrawal as the dominant source of subsidence, with some contribution from tectonic subsidence in the Quetta Valley. Results of SBAS-InSAR multi-temporal analysis provide a better explanation for the pre-, co-, and post-seismic displacement pattern caused by the 2008 earthquake swarms across two strike-slip faults.

  18. Review: Regional land subsidence accompanying groundwater extraction

    Science.gov (United States)

    Galloway, Devin L.; Burbey, Thomas J.

    2011-01-01

    The extraction of groundwater can generate land subsidence by causing the compaction of susceptible aquifer systems, typically unconsolidated alluvial or basin-fill aquifer systems comprising aquifers and aquitards. Various ground-based and remotely sensed methods are used to measure and map subsidence. Many areas of subsidence caused by groundwater pumping have been identified and monitored, and corrective measures to slow or halt subsidence have been devised. Two principal means are used to mitigate subsidence caused by groundwater withdrawal—reduction of groundwater withdrawal, and artificial recharge. Analysis and simulation of aquifer-system compaction follow from the basic relations between head, stress, compressibility, and groundwater flow and are addressed primarily using two approaches—one based on conventional groundwater flow theory and one based on linear poroelasticity theory. Research and development to improve the assessment and analysis of aquifer-system compaction, the accompanying subsidence and potential ground ruptures are needed in the topic areas of the hydromechanical behavior of aquitards, the role of horizontal deformation, the application of differential synthetic aperture radar interferometry, and the regional-scale simulation of coupled groundwater flow and aquifer-system deformation to support resource management and hazard mitigation measures.

  19. Microstructural changes due to laser surface melting of an AISI 304 stainless steel

    Directory of Open Access Journals (Sweden)

    d?Oliveira A.S.C.M.

    2001-01-01

    Full Text Available Several techniques can be used to improve surface properties. These can involve changes on the surface chemical composition (such as alloying and surface welding processes or on the surface microstructure, such as hardening and melting. In the present work surface melting with a 3kW CO2 cw laser was done to alter surface features of an AISI 304 stainless steel. Microstructure characterisation was done by optical and scanning electron microscopy. Vickers and Knoop microhardness tests evaluated mechanical features after surface melting. Phase transformation during rapid solidification is analysed and discussed.

  20. Spatial-temporal heterogeneity of land subsidence evolution in Beijing based on InSAR and cluster analysis

    Science.gov (United States)

    Ke, Y.; Li, Y.; Gong, H.; Pan, Y.; Zhu, L.; Chen, B.

    2015-12-01

    Land subsidence is a common natural hazard occurring in extensive areas in the world. In Beijing, the capital city of China, there has been serious land subsidence due to overexploitation of ground water during the recent decades. Five major subsidence tunnels have formed. Across the Beijing plain area, the ground is sinking at the rate of 30-100mm/year. Uneven subsidence leads to ground fissure and building destruction, and has caused great economical and property loss. To better characterize and understand regional land subsidence evolution, it is critical to monitor the time-series dynamics of subsidence, and capture the spatial-temporal heterogeneity of the subsidence evolution. Interferometric SAR technique, as it provides high spatial resolution and wide range of observation, have been successfully used to monitor regional ground deformation. The objective of this study is to derive time-series regional land subsidence dynamics in Beijing, and based on which, analyze and assess the spatial-temporal heterogeneity of the evolution using cluster analysis. First, ENVISAT ASAR (2003-2009 years, 28 scenes, track number: 218) datasets during 2003-2010 covering Beijing plain area were utilized to obtain time-series subsidence rate using Persistent Scatter InSAR (PS-InSAR) technique provided in SARProz software. Second, time-series subsidence characteristics of the PS points were analyzed and the PS points were clustered based on Self-Organization feature Maps (SOM) algorithm considering environmental factors such as groundwater level and lithologic characters. This study demonstrates that based on InSAR measurements and SOMs algorithm, the spatial-temporal heterogeneity of land subsidence evolution can be captured. Each cluster shows unique spatial-temporal evolution pattern. The results of this study will facilitate further land subsidence modeling and prediction at regional spatial scale.

  1. Geocenter motion due to surface mass transport from GRACE satellite data

    Science.gov (United States)

    Riva, R. E. M.; van der Wal, W.; Lavallée, D. A.; Hashemi Farahani, H.; Ditmar, P.

    2012-04-01

    Measurements of mass redistribution from satellite gravimetry are insensitive to geocenter motions. However, geocenter motions can be constrained by satellite gravity data alone if we partition mass changes between land and oceans, under the assumption that the ocean is passive (i.e., in gravitational equilibrium with the land load and the solid earth). Here, we make use of 8 years (2003-2010) of optimally filtered monthly GRACE-based solutions produced at TU Delft to determine changes in the land load and the corresponding geocenter motion, through an iterative procedure. We pay particular attention to correcting for signal leakage caused by the limited spatial resolution of GRACE. We also investigate how the choice of a model of glacial isostatic adjustment (GIA) affects the estimated geocenter motion trend due to present-day surface mass transport. Finally, we separate the contribution of ice masses from that of land hydrology and show how they have a different sensitivity to the chosen GIA model and observational time-span.

  2. GPS geodetic measurements of subsidence from groundwater drawdown in central Arkansas

    Science.gov (United States)

    Jansma, P.; Mattioli, G.; Marshall, A.; Czarnecki, J.

    2005-05-01

    The state of Arkansas ranks fifth in the nation in ground water consumption, largely fueled by its robust rice and manufacturing industries. The region centered on Lonoke, Arkansas, Jefferson and Monroe counties in the center of the state has seen dramatic drawdown of its ground-water resources and development of significant cones of depression. Subsidence of 1.5 meters over a few decades was postulated for portions of Arkansas county on the basis of elevation changes of benchmarks. These results were preliminary and measurements were not made with geodetic grade equipment. Validation of these results is the primary goal of our on-going work. We are developing an extensive network of suitable benchmarks throughout central and eastern Arkansas, whose vertical position can be monitored using high-precision Global Positioning System geodesy. Campaign GPS measurements were first obtained in summer 2003. Second epoch observations were acquired throughout 2004. Although errors are high due to the limited temporal dataset, preliminary GPS geodetic results are consistent with subsidence of the ground surface above the cones of depression on the order of tens of millimeters per year.

  3. Regional subsidence history and 3D visualization with MATLAB of the Vienna Basin, central Europe

    Science.gov (United States)

    Lee, E.; Novotny, J.; Wagreich, M.

    2013-12-01

    This study reconstructed the subsidence history by the backstripping and 3D visualization techniques, to understand tectonic evolution of the Neogene Vienna Basin. The backstripping removes the compaction effect of sediment loading and quantifies the tectonic subsidence. The amount of decompaction was calculated by porosity-depth relationships evaluated from seismic velocity data acquired from two boreholes. About 100 wells have been investigated to quantify the subsidence history of the Vienna Basin. The wells have been sorted into 10 groups; N1-4 in the northern part, C1-4 in the central part and L1-2 in the northernmost and easternmost parts, based on their position within the same block bordered by major faults. To visualize 3D subsidence maps, the wells were arranged to a set of 3D points based on their map location (x, y) and depths (z1, z2, z3 ...). The division of the stratigraphic column and age range was arranged based on the Central Paratethys regional Stages. In this study, MATLAB, a numerical computing environment, was used to calculate the TPS interpolation function. The Thin-Plate Spline (TPS) can be employed to reconstruct a smooth surface from a set of 3D points. The basic physical model of the TPS is based on the bending behavior of a thin metal sheet that is constrained only by a sparse set of fixed points. In the Lower Miocene, 3D subsidence maps show strong evidence that the pre-Neogene basement of the Vienna Basin was subsiding along borders of the Alpine-Carpathian nappes. This subsidence event is represented by a piggy-back basin developed on top of the NW-ward moving thrust sheets. In the late Lower Miocene, Group C and N display a typical subsidence pattern for the pull-apart basin with a very high subsidence event (0.2 - 1.0 km/Ma). After the event, Group N shows remarkably decreasing subsidence, following the thin-skinned extension which was regarded as the extension model of the Vienna Basin in the literature. But the subsidence in

  4. Long Wall Mining Subsidence and Fluvial Stream Changes: an Ecological Perspective

    Science.gov (United States)

    Spear, R.; Proch, T.

    2005-05-01

    Long wall mining is a high efficiency underground coal extraction technique that removes large panels of coal and causes immediate subsidence of the overburden. Surface subsidence may vary between 0.3 meters and 2 meters depending on the depth of the coal seam. Fractures in the overburden allow perched water tables to drain to greater depths and dries up their associated springs. Base flow in headwater streams is often eliminated. Subsidence also changes the physical characteristics of streams. Typical riffle pool sequences are replaced with long pools and glides. Benthic invertebrate and fish community assemblages reflect the physical habitat changes. EPT invertebrate taxa are replaced with Odonates and Diptera larvae associated with glide/pool habitat. Fish community diversity is negatively impacted. Diverse riffle dwelling assemblages are replaced and dominated by increasingly homogenous pool dwelling fish communities. Stream subsidence effectively increases the stream order without increasing its size or flow regime.

  5. The Land Subsidence and Relative Sea Level Rise in Chinese Delta Areas

    Institute of Scientific and Technical Information of China (English)

    YeYincan; LiuDujuan

    2004-01-01

    Based on some experts' research effort, the problems of land subsidence and relative sea level rise in three Chinese delta areas(Huanghe, Changjiang and Zhujiang Delta) are analyzed and discussed in this paper. The authors' opinion is that the land subsidence is mainly induced by human activity and has made the greater contributions to the relative sea level rise and become one of the geological hazards in these areas. In Tianjin and Shanghai areas where had ever existed serious land subsidence problem, due to the positive and effective control methods, the ratio of man-induced land subsidence to relative sea level rise decreased from 80% - 90% in 1960s - 1970s to less than 60% at present. But it is estimated that in the next tens of years this ratio will still be considerable. So human being must keep its eyes on this phenomenon and take more positive countermeasures to control the land subsidenee.

  6. Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA

    Science.gov (United States)

    Deverel, Steven J.; Ingrum, Timothy; Leighton, David

    2016-05-01

    Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr-1. Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr-1 where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from 1.8 cm yr-1. The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr-1. These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr-1.

  7. Catastrophic subsidence: An environmental hazard, shelby county, Alabama

    Science.gov (United States)

    Lamoreaux, Philip E.; Newton, J. G.

    1986-03-01

    Induced sinkholes (catastrophic subsidence) are those caused or accelerated by human activities These sinkholes commonly result from a water level decline due to pumpage Construction activities in a cone of depression greatly increases the likelihood of sinkhole occurrence Almost all occur where cavities develop in unconsolidated deposits overlying solution openings in carbonate rocks. Triggering mechanisms resulting from water level declines are (1) loss of buoyant support of the water, (2) increased gradient and water velocity, (3) water-level fluctuations, and (4) induced recharge Construction activities triggering sinkhole development include ditching, removing overburden, drilling, movement of heavy equipment, blasting and the diversion and impoundment of drainage Triggering mechanisms include piping, saturation, and loading Induced sinkholes resulting from human water development/management activities are most predictable in a youthful karst area impacted by groundwater withdrawals Shape, depth, and timing of catastrophic subsidence can be predicted in general terms Remote sensing techniques are used in prediction of locations of catastrophic subsidence. This provides a basis for design and relocation of structures such as a gas pipeline, dam, or building Utilization of techniques and a case history of the relocation of a pipeline are described

  8. Surface deformation due to slow slip source considering a non-elastic medium

    Science.gov (United States)

    Voss, N. K.; Malservisi, R.; Dixon, T. H.; Protti, M.

    2016-12-01

    Slow slip events (SSEs) are now recognized as a feature common in many subduction zones. They have been recognized in both the shallow part of subduction interface as well as deeper, beneath the seismogenic zone. While shallow events are difficult to image due to lack of resolution with onshore instrumentation, deep events appear to correlate well with seismic phenomena including tremor and low frequency events. However, uncertainty regarding source properties of the events and their surrounding medium remains high at these depths. Deep slow slip appears to be located between 60 and 25 km depth at many locations worldwide (Schwartz and Rokosky , 2007). This places the events at depths at or near the mantle wedge corner. Serpentinization of the mantle wedge is thought to be one source of fluids commonly attributed as the source of SSEs and tremor (Wada et al., 2008) but also leads to drastic changes in rheology of the down going slab and near by mantle. Traditionally, measured geodetic transients are inverted for slip distributions using a simple elastic "Okada" type models. Often the shape of these transients is attributed to variance in slip rate on the fault. Here we explore the response of the surrounding lithosphere to the transient stress propagation induced by SSE and the effects on observed surface deformation using varying rheologies within a finite element model. Understanding these effects allows a better estimation of the uncertainty in the geodetically derived slip distributions thus is important to consider when evaluating SSEs role in earthquake hazard as well as deciphering the relationship between tremor and slip.

  9. Coastal city subsidence in Shenzhen (China), monitored using multi-frequency radar interferometry time-series techniques

    Science.gov (United States)

    Liu, Peng; Li, Yongsheng; Singleton, Andrew; Li, Qingquan; Zhang, Jingfa; Li, Zhenhong

    2014-05-01

    In just 26 years, the coastal city of Shenzhen (Southern China) has been transformed from a small fishing village to a modern city with a population exceeding 8.5 million people. Following its designation as a Special Economic Zone in the 1980s, the city became a test bed for China's economic reforms and currently leads many new practices in urban planning. The rapid economic development was matched by a sharp increase in the demand for usable land and consequently, extensive coastal reclamation has been undertaken by piling rock fragments from nearby hills onto the seabed. However, it has recently been reported that new apartments, offices and transport networks built on the reclaimed land have become unusable due to ground subsidence. The additional threat of coastal inundation from sea-level rise also requires serious consideration. InSAR time-series techniques (such as Persistent Scatterer and Small Baseline InSAR) are capable of detecting sub-centimetre elevation changes of the Earth's surface over large areas and at a density far exceeding the capabilities of a GPS network - particularly for such an urban environment as Shenzhen. This study uses numerous independent tracks of SAR data (two ENVISAT C-band tracks and two ALOS L-band tracks) to determine the surface movements between 2004 and 2013. Quantitative comparative analyses are carried out in the overlapping area between two adjacent tracks, and thus no ground data is required to validate InSAR results. The results show greatest subsidence in coastal areas with the areas of reclaimed land also predominantly undergoing subsidence. The combination of different ascending and descending tracks allows 2D velocity fields to be estimated and it will be important to determine whether the subsidence from the recently reclaimed land is consolidation or part of a longer-term trend. This ability to provide accurate measurements of ground stability for the city of Shenzhen will help focus investigations into areas of

  10. Integrating wireless sensor network for monitoring subsidence phenomena

    Science.gov (United States)

    Marturià, Jordi; Lopez, Ferran; Gigli, Giovanni; Intrieri, Emanuele; Mucchi, Lorenzo; Fornaciai, Alessandro

    2016-04-01

    An innovative wireless sensor network (WSN) for the 3D superficial monitoring of deformations (such as landslides and subsidence) is being developed in the frame of the Wi-GIM project (Wireless sensor network for Ground Instability Monitoring - LIFE12 ENV/IT/001033). The surface movement is detected acquiring the position (x, y and z) by integrating large bandwidth technology able to detect the 3D coordinates of the sensor with a sub-meter error, with continuous wave radar, which allows decreasing the error down to sub-cm. The Estació neighborhood in Sallent is located over the old potassium mine Enrique. This zone has been affected by a subsidence process over more than twenty years. The implementation of a wide network for ground auscultation has allowed monitoring the process of subsidence since 1997. This network consists of: i) a high-precision topographic leveling network to control the subsidence in surface; ii) a rod extensometers network to monitor subsurface deformation; iii) an automatic Leica TCA Total Station to monitor building movements; iv) an inclinometers network to measure the horizontal displacements on subsurface and v) a piezometer to measure the water level. Those networks were implemented within an alert system for an organized an efficient response of the civil protection authorities in case of an emergency. On 23rd December 2008, an acceleration of subsoil movements (of approx. 12-18 cm/year) provoked the activation of the emergency plan by the Catalan Civil Protection. This implied the preventive and scheduled evacuation of the neighbours (January 2009) located in the area with a higher risk of collapse: around 120 residents of 43 homes. As a consequence, the administration implemented a compensation plan for the evacuation of the whole neighbourhood residents and the demolition of 405 properties. In this work, the adaptation and integration process of Wi-GIM system with those conventional monitoring network are presented for its testing

  11. Subsidence of ash-flow calderas: Relation to caldera size and magma-chamber geometry

    Science.gov (United States)

    Lipman, P.W.

    1997-01-01

    Diverse subsidence geometries and collapse processes for ash-flow calderas are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary calderas, a continuum of geometries and subsidence styles is inferred to exist, in both island-arc and continental settings, between small funnel calderas and larger plate (piston) subsidences bounded by arcuate faults. Within most ring-fault calderas, the subsided block is variably disrupted, due to differential movement during ash-flow eruptions and postcollapse magmatism, but highly chaotic piecemeal subsidence appears to be uncommon for large-diameter calderas. Small-scale downsag structures and accompanying extensional fractures develop along margins of most calderas during early stages of subsidence, but downsag is dominant only at calderas that have not subsided deeply. Calderas that are loci for multicyclic ash-flow eruption and subsidence cycles have the most complex internal structures. Large calderas have flared inner topographic walls due to landsliding of unstable slopes, and the resulting slide debris can constitute large proportions of caldera fill. Because the slide debris is concentrated near caldera walls, models from geophysical data can suggest a funnel geometry, even for large plate-subsidence calderas bounded by ring faults. Simple geometric models indicate that many large calderas have subsided 3-5 km, greater than the depth of most naturally exposed sections of intracaldera deposits. Many ring-fault platesubsidence calderas and intrusive ring complexes have been recognized in the western U.S., Japan, and elsewhere, but no well-documented examples of exposed eroded calderas have large-scale funnel geometry or chaotically disrupted caldera floors. Reported ignimbrite "shields" in the central Andes, where large-volume ash-flows are inferred to

  12. Features of electromagnetic waves in a complex plasma due to surface plasmon resonances on macroparticles

    CERN Document Server

    Vladimirov, S V

    2015-01-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations significantly modifies plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The results are discussed in the context of dusty plasma experiments.

  13. Hydrogel Inverse Replicas of Breath Figures Exhibit Superoleophobicity Due to Patterned Surface Roughness.

    Science.gov (United States)

    Arora, Jaspreet Singh; Cremaldi, Joseph C; Holleran, Mary Kathleen; Ponnusamy, Thiruselvam; He, Jibao; Pesika, Noshir S; John, Vijay T

    2016-02-02

    The wetting behavior of a surface depends on both its surface chemistry and the characteristics of surface morphology and topography. Adding structure to a flat hydrophobic or oleophobic surface increases the effective contact angle and thus the hydrophobicity or oleophobicity of the surface, as exemplified by the lotus leaf analogy. We describe a simple strategy to introduce micropatterned roughness on surfaces of soft materials, utilizing the template of hexagonally packed pores of breath figures as molds. The generated inverse replicas represent micron scale patterned beadlike protrusions on hydrogel surfaces. This added roughness imparts superoleophobic properties (contact angle of the order of 150° and greater) to an inherently oleophobic flat hydrogel surface, when submerged. The introduced pattern on the hydrogel surface changes morphology as it swells in water to resemble morphologies remarkably analogous to the compound eye. Analysis of the wetting behavior using the Cassie-Baxter approximation leads to estimation of the contact angle in the superoleophobic regime and in agreement with the experimental value.

  14. Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

    Science.gov (United States)

    Marketos, G.; Spiers, C. J.; Govers, R.

    2016-06-01

    Accurate forward modeling of surface subsidence above producing hydrocarbons reservoirs requires an understanding of the mechanisms determining how ground deformation and subsidence evolve. Here we focus entirely on rock salt, which overlies a large number of reservoirs worldwide, and specifically on the role of creep of rock salt caprocks in response to production-induced differential stresses. We start by discussing available rock salt creep flow laws. We then present the subsidence evolution above an axisymmetric finite element representation of a generic reservoir that extends over a few kilometers and explore the effects of rock salt flow law choice on the subsidence response. We find that if rock salt creep is linear, as appropriate for steady state flow by pressure solution, the subsidence response to any pressure reduction history contains two distinct components, one that leads to the subsidence bowl becoming narrower and deeper and one that leads to subsidence rebound and becomes dominant at later stages. This subsidence rebound becomes inhibited if rock salt deforms purely through steady state power law creep at low stresses. We also show that an approximate representation of transient creep leads to relatively small differences in subsidence predictions. Most importantly, the results confirm that rock salt flow must be modeled accurately if good subsidence predictions are required. However, in practice, large uncertainties exist in the creep behavior of rock salt, especially at low stresses. These are a consequence of the spatial variability of rock salt physical properties, which is practically impossible to constrain. A conclusion therefore is that modelers can only resort to calculating bounds for the subsidence evolution above producing rock salt-capped reservoirs.

  15. November 2016 West Hackberry Subsidence Report

    Energy Technology Data Exchange (ETDEWEB)

    Moriarty, Dylan Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lord, Anna C. Snider [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    Subsidence monitoring is a critical component to understanding the cavern integrity of salt storage caverns. This report looks at historical and recent data from two of the three West Hackberry dome cavern operators. DOE SPR and LA Storage are coordinating subsidence surveys to create a comprehensive understanding of ground movement above the dome. Data from annual level and rod surveys, GPS, and tiltmeter data show the sites are experiencing typical ground movement. The highest subsidence rate is seen in the middle of the DOE SPR site at just under one inch per year with less ground movement around the edge of the site. A GPS and tiltmeter instrument in the northeast areas of the DOE SPR site has not seen any trend change since the devices were installed in 2013. Comparison between recent ground movement data and historical trends suggest that there is no reason to believe that any DOE SPR or LA Storage caverns have been structurally compromised.

  16. Robust processing of mining subsidence monitoring data

    Energy Technology Data Exchange (ETDEWEB)

    Wang Mingzhong; Huang Guogang [Pingdingshan Mining Bureau (China); Wang Yunjia; Guogangli [China Univ. of Mining and Technology, Xuzhou (China)

    1996-12-31

    Since China began to do research on mining subsidence in 1950s, more than one thousand lines have been observed. Yet, monitoring data sometimes contain quite a lot of outliers because of the limit of observation and geological mining conditions. In China, nowdays, the method of processing mining subsidence monitoring data is based on the principle of the least square method. It is possible to produce lower accuracy, less reliability, or even errors. For reason given above, the authors, according to Chinese actual situation, have done some research work on the robust processing of mining subsidence monitoring data in respect of how to get prediction parameters. The authors have derived related formulas, designed some computational programmes, done a great quantity of actual calculation and simulation, and achieved good results. (orig.)

  17. Subsidence and collapse sinkholes in soluble rock: a numerical perspective

    Science.gov (United States)

    Kaufmann, Georg; Romanov, Douchko; Hiller, Thomas

    2016-04-01

    Soluble rocks such as limestone, gypsum, anhydrite, and salt are prone to subsidence and the sudden creation of collapse sinkholes. The reason for this behaviour stems from the solubility of the rock: Water percolating through fissures and bedding partings can remove material from the rock walls and thus increase the permeability of the host rock by orders of magnitudes. This process occurs on time scales of 1,000-100,000 years, resulting in enlarged fractures, voids and cavities, which then carry flow efficiently through the rock. The enlargement of sub-surface voids to the meter-size within such short times creates mechanical conditions prone to collapse. The collapse initiates at depth, but then propagates to the surface. By means of numerical modelling, we discuss the long-term evolution of secondary porosity in gypsum rocks, resulting in zones of sub-surface voids, which then become mechanically unstable and collapse. We study two real-world case scenarios, in which we can relate field observations to our numerical model: (i) A dam-site scenario, where flow around the dam caused widespread dissolution of gypsum and subsequent subsidence of the dam and a nearby highway. (ii) A natural collapse sinkhole forming as a result of freshwater inflow into a shallow anhydrite formation with rapid evolution of voids in the sub-surface.

  18. Monitoring subsidence rates along road network by persistent scatterer SAR interferometry with high-resolution TerraSAR-X imagery

    Institute of Scientific and Technical Information of China (English)

    Bing Yu; Guoxiang Liu; Rui Zhang; Hongguo Jia; Tao Li; Xiaowen Wang; Keren Dai; Deying Ma

    2013-01-01

    Ground subsidence is one of the key factors damaging transportation facilities, e.g., road networks consisting of highways and railways. In this paper, we propose to apply the persistent scatterer synthetic aperture radar interferometry (PS-InSAR) approach that uses high-resolution TerraSAR-X (TSX) imagery to extract the regional scale subsidence rates (i.e., average annual sub-sidence in mm/year) along road networks. The primary procedures involve interferometric pair selection, interfer-ogram generation, persistent scatterer (PS) detection, PS networking, phase parameterization, and subsidence rate estimation. The Xiqing District in southwest Tianjin (China) is selected as the study area. This district contains one railway line and several highway lines. A total of 15 TSX images covering this area between April 2009 and June 2010 are utilized to obtain the subsidence rates by using the PS-InSAR (PSI) approach. The subsidence rates derived from PSI range from -68.7 to -1.3 mm/year. These findings show a significantly uneven subsidence pattern along the road network. Comparison between the PSI-derived subsidence rates and the leveling data obtained along the highways shows that the mean and standard deviation (SD) of the discrepancies between the two types of subsidence rates are 0.1 and ±3.2 mm/year, respec-tively. The results indicate that the high-resolution TSX PSI is capable of providing comprehensive and detailed subsidence information regarding road networks with millimeter-level accuracy. Further inspections under geo-logical conditions and land-use categories in the study area indicate that the observed subsidence is highly related to aquifer compression due to groundwater pumping. There-fore, measures should be taken to mitigate groundwater extraction for the study area.

  19. Anatomy of Subsidence in Tianjin from Time Series InSAR

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2016-03-01

    Full Text Available Groundwater is a major source of fresh water in Tianjin Municipality, China. The average rate of groundwater extraction in this area for the last 20 years fluctuates between 0.6 and 0.8 billion cubic meters per year. As a result, significant subsidence has been observed in Tianjin. In this study, C-band Envisat (Environmental Satellite ASAR (Advanced Synthetic Aperture Radar images and L-band ALOS (Advanced Land Observing Satellite PALSAR (Phased Array type L-band Synthetic Aperture Radar data were employed to recover the Earth’s surface evolution during the period between 2007 and 2009 using InSAR time series techniques. Similar subsidence patterns can be observed in the overlapping area of the ASAR and PALSAR mean velocity maps with a maximum radar line of sight rate of ~170 mm·year−1. The west subsidence is modeled for ground water volume change using Mogi source array. Geological control by major faults on the east subsidence is analyzed. Storage coefficient of the east subsidence is estimated by InSAR displacements and temporal pattern of water level changes. InSAR has proven a useful tool for subsidence monitoring and displacement interpretation associated with underground water usage.

  20. Evaluating Land Subsidence Rates and Their Implications for Land Loss in the Lower Mississippi River Basin

    Directory of Open Access Journals (Sweden)

    Lei Zou

    2015-12-01

    Full Text Available High subsidence rates, along with eustatic sea-level change, sediment accumulation and shoreline erosion have led to widespread land loss and the deterioration of ecosystem health around the Lower Mississippi River Basin (LMRB. A proper evaluation of the spatial pattern of subsidence rates in the LMRB is the key to understanding the mechanisms of the submergence, estimating its potential impacts on land loss and the long-term sustainability of the region. Based on the subsidence rate data derived from benchmark surveys from 1922 to 1995, this paper constructed a subsidence rate surface for the region through the empirical Bayesian kriging (EBK interpolation method. The results show that the subsidence rates in the region ranged from 1.7 to 29 mm/year, with an average rate of 9.4 mm/year. Subsidence rates increased from north to south as the outcome of both regional geophysical conditions and anthropogenic activities. Four areas of high subsidence rates were found, and they are located in Orleans, Jefferson, Terrebonne and Plaquemines parishes. A projection of future landscape loss using the interpolated subsidence rates reveals that areas below zero elevation in the LMRB will increase from 3.86% in 2004 to 19.79% in 2030 and 30.88% in 2050. This translates to a growing increase of areas that are vulnerable to land loss from 44.3 km2/year to 240.7 km2/year from 2011 to 2050. Under the same scenario, Lafourche, Plaquemines and Terrebonne parishes will experience serious loss of wetlands, whereas Orleans and Jefferson parishes will lose significant developed land, and Lafourche parish will endure severe loss of agriculture land.

  1. Subsidence and capillary effects in chalks

    CERN Document Server

    Delage, Pierre; Cui, Yu Jun

    2008-01-01

    Based on the concepts of the mechanics of unsaturated soils where capillary phenomena arise between the wetting fluid (water) and the non-wetting one (air), the subsidence of chalks containing oil (non-wetting fluid) during water injection (wetting fluid) is analysed. It is shown that the collapse phenomenon of unsaturated soils under wetting provides a physical explanation and a satisfactory prediction of the order of magnitude of the subsidence of the chalk. The use of a well established constitutive model for unsaturated soils allows a description of the hydro-mechanical history of the chalk, from its deposition to the oil exploitation.

  2. Six years of land subsidence in shanghai revealed by JERS-1 SAR data

    Science.gov (United States)

    Damoah-Afari, P.; Ding, X.-L.; Li, Z.; Lu, Zhiming; Omura, M.

    2008-01-01

    Differential interferometric synthetic aperture radar (SAR) (DInSAR) has proven to be very useful in mapping and monitoring land subsidence in many regions of the world. Shanghai, China's largest city, is one of such areas suffering from land subsidence as a result of severe withdrawal of groundwater for different usages. DInSAR application in Shanghai with the C-band European Remote Sensing 1 & 2 (ERS-1/2) SAR data has been difficult mainly due to the problem of decorrelation of InSAR pairs with temporal baselines larger than 10 months. To overcome the coherence loss of C-band InSAR data, we used eight L-band Japanese Earth Resource Satellite (JERS-1) SAR data acquired during 2 October 1992 to 15 July 1998 to study land subsidence phenomenon in Shanghai. Three of the images were used to produce two separate digital elevation models (DEMs) of the study area to remove topographic fringes from the interferograms used for subsidence mapping. Six interferograms were used to generate 2 different time series of deformation maps over Shanghai. The cumulative subsidence map generated from each of the time series is in agreement with the land subsidence measurements of Shanghai city from 1990-1998, produced from other survey methods. ?? 2007 IEEE.

  3. Land subsidence in the San Joaquin Valley, California, USA, 2007-2014

    Science.gov (United States)

    Sneed, M.; Brandt, J. T.

    2015-11-01

    Rapid land subsidence was recently measured using multiple methods in two areas of the San Joaquin Valley (SJV): between Merced and Fresno (El Nido), and between Fresno and Bakersfield (Pixley). Recent land-use changes and diminished surface-water availability have led to increased groundwater pumping, groundwater-level declines, and land subsidence. Differential land subsidence has reduced the flow capacity of water-conveyance systems in these areas, exacerbating flood hazards and affecting the delivery of irrigation water. Vertical land-surface changes during 2007-2014 were determined by using Interferometric Synthetic Aperture Radar (InSAR), Continuous Global Positioning System (CGPS), and extensometer data. Results of the InSAR analysis indicate that about 7600 km2 subsided 50-540 mm during 2008-2010; CGPS and extensometer data indicate that these rates continued or accelerated through December 2014. The maximum InSAR-measured rate of 270 mm yr-1 occurred in the El Nido area, and is among the largest rates ever measured in the SJV. In the Pixley area, the maximum InSAR-measured rate during 2008-2010 was 90 mm yr-1. Groundwater was an important part of the water supply in both areas, and pumping increased when land use changed or when surface water was less available. This increased pumping caused groundwater-level declines to near or below historical lows during the drought periods 2007-2009 and 2012-present. Long-term groundwater-level and land-subsidence monitoring in the SJV is critical for understanding the interconnection of land use, groundwater levels, and subsidence, and evaluating management strategies that help mitigate subsidence hazards to infrastructure while optimizing water supplies.

  4. Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Evan; Sheng, Chunyang; Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Shimamura, Kohei; Shimojo, Fuyuki [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan)

    2015-02-07

    Power conversion efficiency of gallium arsenide (GaAs) nanowire (NW) solar cells is severely limited by enhanced charge recombination (CR) at sidewall surfaces, but its atomistic mechanisms are not well understood. In addition, GaAs NWs usually contain a high density of twin defects that form a twin superlattice, but its effects on CR dynamics are largely unknown. Here, quantum molecular dynamics (QMD) simulations reveal the existence of an intrinsic type-II heterostructure at the (110) GaAs surface. Nonadiabatic quantum molecular dynamics (NAQMD) simulations show that the resulting staggered band alignment causes a photoexcited electron in the bulk to rapidly transfer to the surface. We have found orders-of-magnitude enhancement of the CR rate at the surface compared with the bulk value. Furthermore, QMD and NAQMD simulations show unique surface electronic states at alternating (111)A and (111)B sidewall surfaces of a twinned [111]-oriented GaAs NW, which act as effective CR centers. The calculated large surface recombination velocity quantitatively explains recent experimental observations and provides microscopic understanding of the underlying CR processes.

  5. Using Self-Similarity to Simulate Meniscus Evolution Around TMV Due to Surface Diffusion

    Science.gov (United States)

    Potter, Richard; Zhang, Yue; Fakhraai, Zahra

    It has been hypothesized that enhanced surface diffusion allows the formation of stable molecular glasses during physical vapor deposition. The improved properties of these glasses, such as increased density and kinetic stability can help improve material properties in pioneering fields of technology such as organic electronics and pharmaceutical drug delivery. While surface diffusion has been measured previously on the surfaces of organic glasses, direct measurements on the surface of vapor-deposited stable glasses has proven more challenging. This research focuses on a straightforward method for measuring the surface diffusion coefficients of molecular glasses through the use of tobacco mosaic virus (TMV) nanorods as probe particles. In conjunction, mathematical models based on the thin film equation were used to simulate fast meniscus formation around the nanorods on the glassy surface. The evolution of the meniscus is self-similar, which allows quick quantification of the diffusion coefficient, by solving the time evolution for a single experiment. Experimental data were compared and fit to these simulations to derive a quantity for the surface diffusion coefficient, Ds. Nsf-CAREER DMR-1350044.

  6. Subsidence history and forming mechanism of anomalous tectonic subsidence in the Bozhong depression, Bohaiwan basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Bozhong depression of the Bohaiwan basin belongs to a family of extensional basins in East China, but is quite different from other parts of the basin. The Cenozoic subsidence of the depression is controlled by a combination of lithospheric thinning and polycyclic strike-slip movements. Three episodic rifts have been identified, i.e. Paleocence-early Eocene, middle-late Eocene and Oligocene age. The depression underwent syn-rift and post-rift stages, but two episodic dextral movement events of the strike-slip faults modify the subsidence of the Bozhong depression since the Oligocene. The early dextral movement of the Tan-Lu fault associated with crustal extension resulted in accelerated subsidence during the time of deposition of the Dongying Formation with a maximum thickness of 4000 m. A late reactivation of dextral movement of the Tan-Lu fault began in late Miocene (about 12 Ma), which resulted in the intense subsidence of Minghuazhen Formation and Quaternary. In addition, dynamic mantle convection-driven topography also accelerated the post-rift anomalous subsidence since the Miocene (24.6 Ma). Our results indicate that the primary control on rapid subsidence both during the rift and post-rift stages in the Bozhong depression originates from a combination of multiple episodic crustal extension and polycyclic dextral movements of strike-slip faults, and dynamic topography. tectonic subsidence, strike-slip, dynamic topography, Bozhong depression, Bohaiwan basin

  7. Preliminary results of land subsidence monitoring project in Konya Closed Basin between 2006–2009 by means of GNSS observations

    OpenAIRE

    2010-01-01

    One of the potential dangers that might arise as a result of bringing excessive amounts of groundwater to the surface of the Earth is land subsidence. Such surface deformations – these velocities may vary from a few millimetres to a few metres per year – do the greatest damage to infrastructure facilities and buildings in residential units. Agricultural lands, in which excessive irrigation is performed, and densely populated cities are more likely to suffer from land subsidence. Konya Closed ...

  8. Investigating the Impacts of Surface Temperature Anomalies due to Burned Area Albedo in Northern sub-Saharan Africa

    Science.gov (United States)

    Gabbert, T.; Matsui, T.; Capehart, W. J.; Ichoku, C. M.; Gatebe, C. K.

    2015-12-01

    The northern Sub-Saharan African region (NSSA) is an area of intense focus due to periodic severe droughts that have dire consequences on the growing population, which relies mostly on rain fed agriculture for its food supply. This region's weather and hydrologic cycle are very complex and are dependent on the West African Monsoon. Different regional processes affect the West African Monsoon cycle and variability. One of the areas of current investigation is the water cycle response to the variability of land surface characteristics. Land surface characteristics are often altered in NSSA due to agricultural practices, grazing, and the fires that occur during the dry season. To better understand the effects of biomass burning on the hydrologic cycle of the sub-Saharan environment, an interdisciplinary team sponsored by NASA is analyzing potential feedback mechanisms due to the fires. As part of this research, this study focuses on the effects of land surface changes, particularly albedo and skin temperature, that are influenced by biomass burning. Surface temperature anomalies can influence the initiation of convective rainfall and surface albedo is linked to the absorption of solar radiation. To capture the effects of fire perturbations on the land surface, NASA's Unified Weather and Research Forecasting (NU-WRF) model coupled with NASA's Land Information System (LIS) is being used to simulate burned area surface albedo inducing surface temperature anomalies and other potential effects to environmental processes. Preliminary sensitivity results suggest an altered surface radiation budget, regional warming of the surface temperature, slight increase in average rainfall, and a change in precipitation locations.

  9. Experimental studies of the streaming flow due to the adsorption of particles at a liquid surface

    Science.gov (United States)

    Singh, Pushpendra; Musunuri, Naga; Fischer, Ian

    2016-11-01

    The particle image velocimetry (PIV) technique is used to study the streaming flow that is induced when particles are adsorbed at a liquid surface. The flow develops within a fraction of second after the adsorption of the particle and persists for several seconds. The fluid directly below the particle rises upward, and near the surface, it moves away from the particle. The flow causes powders sprinkled on a liquid surface to disperse on the surface. The flow strength, and the volume over which it extends, decreases with decreasing particle size. The streaming flow induced by the adsorption of two or more particles is a combination of the flows which they induce individually. The work was supported by National Science Foundation.

  10. Numerical study on cavitating flow due to a hydrofoil near a free surface

    Directory of Open Access Journals (Sweden)

    Ping-Chen Wu

    2016-09-01

    Full Text Available A numerical strategy is proposed for a viscous uniform flow past a 2-D partially cavitating hydrofoil placed at a finite depth from the free surface. The flow was modeled by the Reynolds-averaged Navier–Stokes (RANS equations. A finite-volume method with the SIMPLE scheme and k-ε turbulence model were employed for computations. The “full cavitation model,” which included the effects of vaporization, noncondensible gases and compressibility, was incorporated in the computation of cavitating flow. The cavity shape and free surface were updated iteratively till a reasonable convergence was reached. As for the determination of the free surface, the VOF approach was adopted. The test cases show the accuracy and stability of our procedure to capture the cavitating flow near the free surface.

  11. Oxidation of the Martian surface - Constraints due to chemical processes in the atmosphere

    Science.gov (United States)

    Mcelroy, M. B.; Kong, T. Y.

    1976-01-01

    Dissociation of water in the Martian atmosphere may supply oxygen to the surface and may result in the formation of minerals such as goethite, as proposed by Huguenin. The supply rate is limited by chemical processes in the atmosphere which regulate the abundance of O2. The net surface sink for atmospheric oxygen can be as large as 33 million atoms per sq cm per sec which compares to the escape rate of 60 million atoms per sq cm per sec.

  12. Cost-effective monitoring of land subsidence in developing countries using semipermanent GPS stations: a test study over Houston, Texas

    Science.gov (United States)

    Kim, Donghwan; Lee, Hyongki; Okeowo, Modurodoluwa A.; Basnayake, Senaka; Jayasinghe, Susantha

    2017-04-01

    We present a cost-effective method for monitoring land subsidence in developing countries using measurements from semipermanent global positioning system (GPS) stations and interferometric synthetic aperture radar (InSAR) observations. The cost of maintaining a network of permanent GPS stations to monitor subsidence in developing countries might be implausible due to the high cost of maintenance. Hence, semipermanent GPS stations could be an alternative method, which densifies a GPS network with relatively inexpensive costs. We used three statistical methods to estimate the subsidence. We investigated the optimum time intervals for semipermanent GPS measurements based on the similarities of subsidence magnitudes and curve patterns with the permanent GPS measurements. In addition, we assessed the open source GPS processing tools based on the data quality of different session durations. Among the three models, the smoothing spline model showed the best estimation of subsidence. Among the different time interval data, 10- or 30-day time interval data were optimum for semipermanent GPS stations. Finally, we compared the GPS results to the InSAR-derived subsidence result, and both methods show that the northwestern Houston area subsides by about 1.5 to 2.0 cm/year. We anticipate that our method can be applied to other cities experiencing subsidence in developing countries.

  13. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng

    2017-03-28

    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  14. Semi-analytic modelling of subsidence

    NARCIS (Netherlands)

    Fokker, P.A.; Orlic, B.

    2006-01-01

    This paper presents a forward model for subsidence prediction caused by extraction of hydrocarbons. The model uses combinations of analytic solutions to the visco-elastic equations, which approximate the boundary conditions. There are only a few unknown parameters to be estimated, and, consequently,

  15. Computational simulation of surface waviness in graphite/epoxy woven composites due to initial curing

    Science.gov (United States)

    Sanfeliz, Jose G.; Murthy, Pappu L. N.; Chamis, Christos C.

    1992-01-01

    Several models simulating plain weave, graphite/epoxy woven composites are presented, along with the effects that the simultaneous application of pressure and thermal loads have on their surfaces. The surface effects created by moisture absorption are also examined. The computational simulation consisted of using a two-dimensional finite element model for the composite. The properties of the finite element (FE) model are calculated by using the in-house composite mechanics computer code ICAN (Integrated Composite ANalyzer). MSC/NASTRAN is used for the FE analysis which yields the composite's top surface normalized displacements. These results demonstrate the importance of parameters such as the cure temperature (T sub o) and the resin content in the curing process of polymer-matrix composites. The modification of these parameters will help tailor the composite system to the desired requirements and applications.

  16. Frequency shifts of resonant modes of the Sun due to near-surface convective scattering

    CERN Document Server

    Bhattacharya, Jishnu; Antia, H M

    2015-01-01

    Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modeled frequencies, a phenomenon referred to as the "surface term." The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modeling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelengths (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun....

  17. Nanocrystals in compression: unexpected structural phase transition and amorphization due to surface impurities

    Science.gov (United States)

    Liu, Gang; Kong, Lingping; Yan, Jinyuan; Liu, Zhenxian; Zhang, Hengzhong; Lei, Pei; Xu, Tao; Mao, Ho-Kwang; Chen, Bin

    2016-06-01

    We report an unprecedented surface doping-driven anomaly in the compression behaviors of nanocrystals demonstrating that the change of surface chemistry can lead to an interior bulk structure change in nanoparticles. In the synchrotron-based X-ray diffraction experiments, titania nanocrystals with low concentration yttrium dopants at the surface are found to be less compressible than undoped titania nanocrystals. More surprisingly, an unexpected TiO2(ii) phase (α-PbO2 type) is induced and obvious anisotropy is observed in the compression of yttrium-doped TiO2, in sharp contrast to the compression behavior of undoped TiO2. In addition, the undoped brookite nanocrystals remain with the same structure up to 30 GPa, whereas the yttrium-doped brookite amorphizes above 20 GPa. The abnormal structural evolution observed in yttrium-doped TiO2 does not agree with the reported phase stability of nano titania polymorphs, thus suggesting that the physical properties of the interior of nanocrystals can be controlled by the surface, providing an unconventional and new degree of freedom in search for nanocrystals with novel tunable properties that can trigger applications in multiple areas of industry and provoke more related basic science research.We report an unprecedented surface doping-driven anomaly in the compression behaviors of nanocrystals demonstrating that the change of surface chemistry can lead to an interior bulk structure change in nanoparticles. In the synchrotron-based X-ray diffraction experiments, titania nanocrystals with low concentration yttrium dopants at the surface are found to be less compressible than undoped titania nanocrystals. More surprisingly, an unexpected TiO2(ii) phase (α-PbO2 type) is induced and obvious anisotropy is observed in the compression of yttrium-doped TiO2, in sharp contrast to the compression behavior of undoped TiO2. In addition, the undoped brookite nanocrystals remain with the same structure up to 30 GPa, whereas the yttrium

  18. Subsidence and soil CO2 efflux in tropical peatland in southern Thailand under various water table and management conditions

    Directory of Open Access Journals (Sweden)

    T. Nagano

    2013-12-01

    Full Text Available At the Bacho peatland in southern Thailand, peat subsidence was measured at four locations on abandoned agricultural land (degraded peat swamp forest and at one location in a conservation zone, at monthly intervals over a period of more than 20 years. Average peat subsidence rates during the observation period were 3.1–5.2 cm y−1 on the degraded peatland, reducing to 1.8–2.6 cm y−1 when peat loss due to field fires was discounted, and 1.0 cm y−1 reducing to 0.7 cm y-1 in the conservation zone. Due to martial law restrictions on access to the Bacho site, measurements of the peat soil respiration rate under various water table conditions were made mostly at other sites in Thailand with similar climate. During these measurements the position of the water table ranged from 0.92 m above the peat surface to more than one metre below it, and daily mean respiration rates ranged from 0.57 to 8.20 μmol CO2 m−2 s−1. The CO2 efflux attributed to peat respiration was 13.7–18.9 Mg ha−1 y−1 on the degraded peatland but only 7.5 Mg ha−1 y−1 in the conservation zone. To simulate the CO2 efflux resulting from soil respiration at Bacho on the basis of data collected elsewhere, we developed an empirical three-stage model (NAIS Peat Model that treats the position of the water table as a proxy variable. The observed values of peat subsidence were in good agreement with simulated values of CO2 efflux in two tests. The implications for peatland management are considered.

  19. Coral reef evolution on rapidly subsiding margins

    Science.gov (United States)

    Webster, J.M.; Braga, J.C.; Clague, D.A.; Gallup, C.; Hein, J.R.; Potts, D.C.; Renema, W.; Riding, R.; Riker-Coleman, K.; Silver, E.; Wallace, L.M.

    2009-01-01

    A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2-6??m/ka) over the last 500??ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20??ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500??ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate

  20. Experimental Determination of Drag Modifications Due to Elastic Compliant Surfaces Using Quantitative Visual Techniques.

    Science.gov (United States)

    1988-04-27

    developed in the 5.49 mn by 0.4572 m by 0.1524 m test section of a recirculating liquid flow facility, in which deodorized kerosene was used as the...pulses. The aluminum and gelatin surfaces were reflective enough to result in a sharp reflection of the photochromic time line. The point at which the

  1. Investigation of reasons for small changes in energy of UCN due to their interaction with surface

    CERN Document Server

    Lychagin, E V; Nekhaev, G V; Strelkov, A V; Kartashov, D G; Nesvizhevsky, V V

    2002-01-01

    The nature of the phenomenon of small changes in energy of ultracold neutrons (UCN) has been investigated. This phenomenon occurs during collisions of UCN with a surface, which increase the UCN energy by approx 10 sup - sup 7 eV with a probability of 10 sup - sup 8 -10 sup - sup 5 per collision. Such neutrons are named VUCN. It was observed that the preliminary warming up of samples at 500-600 K leads to an increase of the small heating probability P sub V sub U sub C sub N by at least a factor of 100 for a surface of stainless steel and by a factor of 10 for a copper surface. Extremely intensive UCN small heating by a diamond nanopowder has been observed for the first time. The spectrum of these VUCN and the temperature dependence of their heating probability P sub V sub U sub C sub N are similar to those measured earlier for stainless steel, beryllium, and copper. It is not observed small UCN heating, nor nanoparticles on a monocrystalline sapphire surface. That leads to the conclusion that VUCN are produce...

  2. Assessment of Cold Welding Between Separable Contact Surfaces Due to Impact and Fretting under Vacuum

    Science.gov (United States)

    Merstallinger, A.; Sales, M.; Semerad, E.; Dunn, B. D.

    2009-11-01

    A common failure mode seen during the testing and operation of spacecraft is termed "cold welding". European laboratories refer to this as "adhesion", "sticking" or "stiction". This publication is intended to provide the space community with the most recent understanding of the phenomenon of "cold welding" in relation to spacecraft mechanisms with separable contact surfaces. It presents some basic theory and describes a test method and the required equipment. Cold welding between two contacting surfaces can occur under conditions of impact or fretting. These surfaces may be bare metals, or inorganically or organically coated metals and their alloys. Standard procedures for quantifying the propensity of material surface pairs to cold weld to each other are proposed. Of particular interest will be the contact data of different materials, which are presented in numerical form and as tables summarising contacts between materials that can be either recommended or considered unsuitable for use under vacuum. The data have been compiled in a database that can be accessed online.

  3. Subsidence Contours for South Louisiana; UTM 15N NAD83; LRA (2005); [subsidence_contours

    Data.gov (United States)

    Louisiana Geographic Information Center — The GIS data shapefile represents average subsidence contour intervals (0.02 cm/year over 10,000 years) for Coastal LA derived from the following: Kulp, M.A., 2000,...

  4. Quantification of the advected CO2 concentration due to upstream surface fluxes in aircraft vertical profiles

    Science.gov (United States)

    Font, A.; Morguí, J.-A.; Curcoll, R.; Rodó, X.

    2009-04-01

    A model framework which couples the Lagrangian Particle Dispersion Model FLEXPART (LPDM) with the new global surface flux inversion CarbonTracker from NOAA-ESRL (2007B release) is used to quantify the advected CO2 concentration from outbound surface fluxes to measured vertical profiles carried out during different seasons in 2006 at La Muela site in Spain (LMU; 41.60°N, 1.1°W). The Lagrangian Particle Dispersion Model FLEXPART (LPDM) calculates the influence of surface CO2 fluxes upwind of the study area, allowing us to identify those sources or sink areas that strongly modify the CO2 content of air masses that arrives at different altitudes of measured profiles. CarbonTracker is a new assimilation system that informs of global carbon fluxes at 1°x1° at 3 hours resolution. Coupling LPDM results with surface fluxes allows assessing the net CO2 contribution of identified areas to measured concentrations along the profiles above a reference or background concentration. Furthermore, it allows the quantification of the percentage of each component flux (biospheric, anthropogenic and oceanic) to each vertical layer. At LMU, biospheric fluxes account ~70% of total CO2 advection; fossil fuel ~25%; and ~5% is attributed to the oceanic ones. By far, late spring and summer profiles are largely influence by the biospheric component (~90%). Finally, the CO2 concentration above the background value of profiles measured on 22nd February, 13th October and 30th November 2006 are well explained by the advection of upstream surface fluxes. In other profiles examined, the variation of CO2 along the profile is partially explained by the advection of CO2 outbound fluxes.

  5. Electromagnetic fields due to a horizontal electric dipole antenna laid on the surface of a two-layer medium

    Science.gov (United States)

    Tsang, L.; Kong, J. A.

    1974-01-01

    With applications to geophysical subsurface probings, electromagnetic fields due to a horizontal electric dipole laid on the surface of a two-layer medium are solved by a combination of analytic and numerical methods. Interference patterns are calculated for various layer thickness. The results are interpreted in terms of normal modes, and the accuracies of the methods are discussed.

  6. Evidence of regional subsidence and associated interior wetland loss induced by hydrocarbon production, Gulf Coast region, USA

    Science.gov (United States)

    Morton, Robert A.; Bernier, Julie C.; Barras, John A.

    2006-05-01

    Analysis of remote images, elevation surveys, stratigraphic cross-sections, and hydrocarbon production data demonstrates that extensive areas of wetland loss in the northern Gulf Coast region of the United States were associated with large-volume fluid production from mature petroleum fields. Interior wetland losses at many sites in coastal Louisiana and Texas are attributed largely to accelerated land subsidence and fault reactivation induced by decreased reservoir pressures as a result of rapid or prolonged extraction of gas, oil, and associated brines. Evidence that moderately-deep hydrocarbon production has induced land-surface subsidence and reactivated faults that intersect the surface include: (1) close temporal and spatial correlation of fluid production with surficial changes including rapid subsidence of wetland sediments near producing fields, (2) measurable offsets of shallow strata across the zones of wetland loss, (3) large reductions in subsurface pressures where subsidence rates are high, (4) coincidence of orientation and direction of displacement between surface fault traces and faults that bound the reservoirs, and (5) accelerated subsidence rates near producing fields compared to subsidence rates in surrounding areas or compared to geological rates of subsidence. Based on historical trends, subsidence rates in the Gulf Coast region near producing fields most likely will decrease in the future because most petroleum fields are nearly depleted. Alternatively, continued extraction of conventional energy resources as well as potential production of alternative energy resources (geopressured-geothermal fluids) in the Gulf Coast region could increase subsidence and land losses and also contribute to inundation of areas of higher elevation.

  7. A spectral formalism for computing three-dimensional deformations due to surface loads. 1: Theory

    Science.gov (United States)

    Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.

    1994-01-01

    We outline a complete spectral formalism for computing high spatial resolution three-dimensional deformations arising from the surface mass loading of a spherically symmetric planet. The main advantages of the formalism are that all surface mass loads are always described using a consistent mathematical representation and that calculations of deformation fields for various spatial resolutions can be performed by simpley altering the spherical harmonic degree truncation level of the procedure. The latter may be important when incorporating improved observational constraints on a particular surface mass load, when considering potential errors in the computed field associated with mass loading having a spatial scale unresolved by the observational constraints, or when treating a number of global surface mass loads constrained with different spatial resolutions. The advantages do not extend to traditional 'Green's function' approaches which involve surface element discretizations of the global mass loads. Another advantage of the spectral formalism, over the Green's function approach, is that a posteriori analyses of the computed deformation fields are easily performed. In developing the spectral formalism, we consider specific cases where the Earth's mantle is assumed to respond as an elastic, slightly anelastic, or linear viscoelastic medium. In the case of an elastic or slightly anelastic mantle rheology the spectral response equations incorporate frequency dependent Love numbers. The formalism can therefore be used, for example, to compute the potentially resonant deformational response associated with the free core nutation and Chandler wobble eigenfunctions. For completeness, the spectral response equations include both body forces, as arise from the gravitational attraction of the Sun and the Moon, and surface mass loads. In either case, and for both elastic and anelastic mantle rheologies, we outline a pseudo-spectral technique for computing the ocean

  8. Land subsidence in the southwestern Mojave Desert, California, 1992–2009

    Science.gov (United States)

    Brandt, Justin; Sneed, Michelle

    2017-07-19

    Groundwater has been the primary source of domestic, agricultural, and municipal water supplies in the southwestern Mojave Desert, California, since the early 1900s. Increased demands on water supplies have caused groundwater-level declines of more than 100 feet (ft) in some areas of this desert between the 1950s and the 1990s (Stamos and others, 2001; Sneed and others, 2003). These water-level declines have caused the aquifer system to compact, resulting in land subsidence. Differential land subsidence (subsidence occurring at different rates across the landscape) can alter surface drainage routes and damage surface and subsurface infrastructure. For example, fissuring across State Route 247 at Lucerne Lake has required repairs as has pipeline infrastructure near Troy Lake.Land subsidence within the Mojave River and Morongo Groundwater Basins of the southwestern Mojave Desert has been evaluated using InSAR, ground-based measurements, geology, and analyses of water levels between 1992 and 2009 (years in which InSAR data were collected). The results of the analyses were published in three USGS reports— Sneed and others (2003), Stamos and others (2007), and Solt and Sneed (2014). Results from the latter two reports were integrated with results from other USGS/ MWA cooperative groundwater studies into the broader scoped USGS Mojave Groundwater Resources Web site (http://ca.water.usgs.gov/ mojave/). This fact sheet combines the detailed analyses from the three subsidence reports, distills them into a longer-term context, and provides an assessment of options for future monitoring.

  9. Characteristics of spatio-temporal evolution in Beijing land subsidence, 2003-2009, using PS-InSAR technology

    Science.gov (United States)

    Gu, Z.; Gong, H.; Lu, X.; Zhang, Y.; Chen, B.; Liu, H.; Wang, S.

    2013-12-01

    Two thirds of water supply in Beijing city has come from groundwater, surveyed by Beijing Institute of Hydrogeology and Engineering Geology. During the past several years, Beijing city has suffers severe groundwater decline and land subsidence, induced by continuous over-exploitation of groundwater for nearly 60 years. The maximum of subsidence has reached up to 1096mm since 60 decades, and the rates in these subsidence bowls is between 10 mm/yr to 20 mm/yr, and The cumulative subsidence greater than 300mm is up to 1300km2, which pose a great challenge to public infrastructure and mitigate hazard in Beijing municipal. Permanent Scatterers Synthetic Aperture Radar Interferometry (PS-InSAR) can quickly obtain surface deformation details with high resolution, compared to traditional leveling and extensometer techniques. In this paper we use PS-InSAR technique and 29 acquisitions by Envisat between 2003 and 2009 to monitor recent land subsidence in Beijing plain area. we studied the characteristics of spatio-temporal evolution of Beijing subsidence. The results suggests subsidence bowls have been bounded together in Beijing plain area, which covers Chaoyang, Changping, Shunyi, Tongzhou area, and the range of subsidence has a eastward trend. With conventional of emergency water resource in Changping, Huairou, Pinggu, the rates have increased from more than 10-20mm/yr to about 20-30mm/yr, 50 percent increase in subsidence bowls. What's more, the spatial and temporal distribution of deformation is not only controlled by tectonic but influenced by stress-strain behavior (elastic - plastic - viscoelastic) of aquifer systems. Keywords: Land Subsidence; PS-InSAR; Beijing; Ground fissure; Stress-strain analysis

  10. Decay of the Greenland Ice Sheet due to surface-meltwater-induced acceleration of basal sliding

    CERN Document Server

    Greve, Ralf

    2009-01-01

    Simulations of the Greenland Ice Sheet are carried out with a high-resolution version of the ice-sheet model SICOPOLIS for several global-warming scenarios for the period 1990-2350. In particular, the impact of surface-meltwater-induced acceleration of basal sliding on the stability of the ice sheet is investigated. A parameterization for the acceleration effect is developed for which modelled and measured mass losses of the ice sheet in the early 21st century agree well. The main findings of the simulations are: (i) the ice sheet is generally very susceptible to global warming on time-scales of centuries, (ii) surface-meltwater-induced acceleration of basal sliding leads to a pronounced speed-up of ice streams and outlet glaciers, and (iii) this ice-dynamical effect accelerates the decay of the Greenland Ice Sheet as a whole significantly, but not catastrophically, in the 21st century and beyond.

  11. Surface uplift and time-dependent seismic hazard due to fluid-injection in eastern Texas

    Science.gov (United States)

    Shirzaei, M.; Ellsworth, W. L.; Tiampo, K. F.; González, P. J.; Manga, M.

    2015-12-01

    US states such as Texas and Oklahoma that produce high-volumes of unconventional oil and gas, are facing a sharp increase in seismicity. Observations of the associated surface deformation and accompanying physical models that unequivocally link the seismicity and waste water injection are scarce. Here, we find that the waste water injection in eastern Texas causes uplift, detectable using radar interferometric data. Combining the uplift and injection data through a poroelastic model allows for the resolution of a complex crustal distribution of hydraulic conductivity and pore pressure. We find that the ~5 years pore pressure increase is capable of triggering the 17 May 2012, Mw 4.8 earthquake, the largest event recorded in east Texas. This study shows that surface deformation data are vital in order to constrain the spatiotemporal variations of the stress field in the vicinity of injection sites.

  12. FREQUENCY SHIFTS OF RESONANT MODES OF THE SUN DUE TO NEAR-SURFACE CONVECTIVE SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, J.; Hanasoge, S.; Antia, H. M. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai-400005 (India)

    2015-06-20

    Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modeled frequencies, a phenomenon referred to as the “surface term.” The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modeling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelengths (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun. We show that the full oscillation equations, in the presence of temporally stationary three-dimensional (3D) flows, can be reduced to an effective “quiet-Sun” wave equation with altered sound speed, Brünt–Väisäla frequency, and Lamb frequency. We derive the modified equation and relations for the appropriate averaging of 3D flows and thermal quantities to obtain the properties of this effective medium. Using flows obtained from 3D numerical simulations of near-surface convection, we quantify their effect on solar oscillation frequencies and find that they are shifted systematically and substantially. We argue therefore that consistent interpretations of resonant frequencies must include modifications to the wave equation that effectively capture the impact of vigorous hydrodynamic convection.

  13. Femoral prosthesis subsidence in asymptomatic patients. A stereophotogrammetric assessment.

    Science.gov (United States)

    Chafetz, N; Baumrind, S; Murray, W R; Genant, H K

    1984-01-01

    A radiographic stereophotogrammetric technique (SPG) was used to evaluate quantitatively the presence of early femoral prosthesis subsidence after total hip arthroplasty (THA). This paper focuses on the measurement of subsidence in 12 patients who remained asymptomatic during the first two years after surgery. Only one of these had SPG estimated subsidence in excess of one millimeter at any timepoint. These findings are consistent with the conclusion that early postoperative subsidence is not a common finding among asymptomatic THA patients.

  14. Pengaruh Land Subsidence terhadap Genangan Banjir dan Rob di Semarang Timur

    Directory of Open Access Journals (Sweden)

    ratih Pujiastuti

    2016-06-01

    Full Text Available Inundation of flood and rob (flood due to high tides in Semarang City is increase wtithin area and depth. It be more seroius condition because of land subsisdence that happened in coastal area of Semarang City. This research is foccused on prediction and mapping of inundation flood and rob due to land subsidence effect in East Semarang, especially Tenggang Watershed and Sringin Watershed. On this research, data analysis including analysis of land subsidence, analysis of hydrological data, analysis of flood discharge with HEC-HMS, hydraulics analysis with HEC-RAS and then mapping the results of the flood inundation with Arc GIS. The inundation will be create with overlay the DEM of flood water level and DEM of topographic. According to the results of analysis is known that minimum land subsidence is 0 cm/year that happened in south area of Semarang and more higher ini north area with maximum land subsidence is 5.58 cm/year. On periode   2014-2031, the contribute of land subsidence to increase the inundation of flood and rob is 1.39%/year.

  15. Convection due to surface-tension gradients. [in reduced gravity spacecraft environments

    Science.gov (United States)

    Ostrach, S.

    1978-01-01

    The use of dimensionless parameters to study fluid motions that could occur in a reduced-gravity environment is discussed. The significance of the Marangoni instability is considered, and the use of dimensionless parameters to investigate problems such as thermo and diffusocapillary flows is described. Characteristics of fluid flow in space are described, and the relation and interaction of motions due to capillarity and buoyancy is examined.

  16. THE THREE DIMENSIONAL MODELS AND THEIR IDENTIFICATION MINING SUBSIDENCE

    Institute of Scientific and Technical Information of China (English)

    WUGe; SHENGuanghan; JIXiaoming; WANGQuanke

    1995-01-01

    The theory and method for selecting the three dimensional prediction models of mining subsidence are studied in this paper. Namely, based on system identification and statistics theory, an optimum mining subsidence prediction model can be selected. The method proved by a typical case has a good prospect for determining the physical model of rock mass for mining subsidence prediction.

  17. Flooding and subsidence in the Thames Gateway: impact on insurance loss potential

    Science.gov (United States)

    Royse, Katherine; Horn, Diane; Eldridge, Jillian; Barker, Karen

    2010-05-01

    In the UK, household buildings insurance generally covers loss and damage to the insured property from a range of natural and human perils, including windstorm, flood, subsidence, theft, accidental fire and winter freeze. Consequently, insurers require a reasoned view on the likely scale of losses that they may face to assist in strategic planning, reinsurance structuring, regulatory returns and general risk management. The UK summer 2007 flood events not only provided a clear indication of the scale of potential losses that the industry could face from an individual event, with £3 billion in claims, but also identified a need for insurers and reinsurers to better understand how events may correlate in time and space, and how to most effectively use the computational models of extreme events that are commonly applied to reflect these correlations. In addition to the potential for temporal clustering of events such as windstorms and floods, there is a possibility that seemingly uncorrelated natural perils, such as floods and subsidence, may impact an insurer's portfolio. Where aggregations of large numbers of new properties are planned, such as in the Thames Gateway, consideration of the potential future risk of aggregate losses due to the combination of perils such as subsidence and flood is increasingly important within the insurance company's strategic risk management process. Whilst perils such as subsidence and flooding are generally considered independent within risk modelling, the potential for one event to influence the magnitude and likelihood of the other should be taken into account when determining risk level. In addition, the impact of correlated, but distinctive, loss causing events on particular property types may be significant, particularly if a specific property is designed to protect against one peril but is potentially susceptible to another. We suggest that flood events can lead to increased subsidence risk due to the weight of additional water

  18. Rotating flow of a nanofluid due to an exponentially stretching surface with suction

    Science.gov (United States)

    Salleh, Siti Nur Alwani; Bachok, Norfifah; Arifin, Norihan Md

    2017-08-01

    An analysis of the rotating nanofluid flow past an exponentially stretched surface with the presence of suction is studied in this work. Three different types of nanoparticles, namely, copper, titania and alumina are considered. The system of ordinary differential equations is computed numerically using a shooting method in Maple software after being transformed from the partial differential equations. This transformation has considered the similarity transformations in exponential form. The physical effect of the rotation, suction and nanoparticle volume fraction parameters on the rotating flow and heat transfer phenomena is investigated and has been described in detail through graphs. The dual solutions are found to appear when the governing parameters reach a certain range.

  19. Surface roughness due to residual ice in the use of low power deicing systems

    Science.gov (United States)

    Shin, Jaiwon; Bond, Thomas H.

    1993-01-01

    Thicknesses of residual ice are presented to provide information on surface contamination and associated roughness during deicing events. Data was obtained from low power ice protection systems tests conducted in the Icing Research Tunnel at NASA Lewis Research Center (LeRC) with nine different deicing systems. Results show that roughness associated with residual ice is not characterized by uniformly distributed roughness. Results also show that deicing systems require a critical mass of ice to generate a sufficient expelling force to remove the ice.

  20. Decay of the Greenland Ice Sheet due to surface-meltwater-induced acceleration of basal sliding

    OpenAIRE

    Greve, Ralf; SUGIYAMA, SHIN

    2009-01-01

    Simulations of the Greenland Ice Sheet are carried out with a high-resolution version of the ice-sheet model SICOPOLIS for several global-warming scenarios for the period 1990-2350. In particular, the impact of surface-meltwater-induced acceleration of basal sliding on the stability of the ice sheet is investigated. A parameterization for the acceleration effect is developed for which modelled and measured mass losses of the ice sheet in the early 21st century agree well. The main findings of...

  1. A NUMERICAL SIMULATION OF THE EFFECT ON CHINESE REGIONAL CLIMATE DUE TO SEASONAL VARIATION OF LAND SURFACE PARAMETERS (PART I)

    Institute of Scientific and Technical Information of China (English)

    孙健; 李维亮; 周秀骥

    2001-01-01

    Sensitivity experiment is an important method to study the effect on regional climate due to seasonal variation of land surface parameters. Using China Regional Climate Model (CRCM)nested in CCM1, we first simulate Chinese regional climate, then two numerical sensitivity experiments on the effect of vegetation and roughness length are made. The results show that:(1) If the vegetation is replaced with the monthly data of 1997, precipitation and land-surface temperature are both changed clearly, precipitation decreases and land surface temperature increases, but there is no regional correspondence between these changes. And the results are much better than the results when climate average vegetation was used in the CRCM. (2) If the roughness length is replaced with the monthly data of 1997, there is significant change on land surface temperature, and there is very good regional correspondence between these changes. But the effect on precipitation is very small.

  2. Large apparent electric size of solid-state nanopores due to spatially extended surface conduction.

    Science.gov (United States)

    Lee, Choongyeop; Joly, Laurent; Siria, Alessandro; Biance, Anne-Laure; Fulcrand, Rémy; Bocquet, Lydéric

    2012-08-08

    Ion transport through nanopores drilled in thin membranes is central to numerous applications, including biosensing and ion selective membranes. This paper reports experiments, numerical calculations, and theoretical predictions demonstrating an unexpectedly large ionic conduction in solid-state nanopores, taking its origin in anomalous entrance effects. In contrast to naive expectations based on analogies with electric circuits, the surface conductance inside the nanopore is shown to perturb the three-dimensional electric current streamlines far outside the nanopore in order to meet charge conservation at the pore entrance. This unexpected contribution to the ionic conductance can be interpreted in terms of an apparent electric size of the solid-state nanopore, which is much larger than its geometric counterpart whenever the number of charges carried by the nanopore surface exceeds its bulk counterpart. This apparent electric size, which can reach hundreds of nanometers, can have a major impact on the electrical detection of translocation events through nanopores, as well as for ionic transport in biological nanopores.

  3. Hydromechanical Simulations of Surface Uplift due to CO2 Injection at In Salah (Invited)

    Science.gov (United States)

    Morris, J. P.; Hao, Y.; Foxall, W.; McNab, W. W.

    2009-12-01

    We present recent simulations of the hydromechanical response of the reservoir and overburden associated with CO2 injection at In Salah. Using the best available field data for the reservoir and fault network properties, we are able to demonstrate excellent agreement between simulation and observation. These results are providing new insight into the fate of the CO2 about one of the injectors where intriguing morphology was observed in surface uplift. Additionally, this work is helping to better establish the advantages and limitations of interpreting surface displacements to guide our understanding of fluid fate. The In Salah Project (a joint venture of BP, StatoilHydro and Sonatrach) includes a CO2 sequestration effort that has successfully injected millions of tons of CO2 into a deep saline formation close to a producing gas field in Algeria. We have been funded by the Joint Industry Project (A consortium consisting of BP, StatoilHydro and Sonatrach, hereafter the JIP) and the U.S. Department of Energy to investigate the role of injection induced mechanical deformation and geochemical alteration at the In Salah CO2 storage project. Here we focus upon the hydromechanical portion of the study. We have performed detailed simulations of the hydromechanical response in the vicinity of the KB-502 CO2 injector specifically because the morphology of the observed surface deformation differed from that above the other injectors at the field. First we performed a geomechanical analysis to predict which faults are flow conduits and which are flow barriers. NUFT simulations were performed based upon this information using permeability fields for the reservoir provided by the JIP. These results indicate that the presence of faults in the vicinity of the KB-502 injector may be responsible for the early breakthrough of CO2 observed at a nearby well, KB-5. We have simulated the mm-scale uplift of the overburden and compared the results with observed deformation using InSAR data

  4. Current Land Subsidence in Tianjin, China Recorded by Three Continuous GPS stations (2010-2014)

    Science.gov (United States)

    Jia, X.; Jing, Q.; Yan, B.; Yu, J.; Gan, W.; Wang, G.

    2014-12-01

    In the past two decades, Global Positioning System (GPS) technologies have been frequently applied to urban subsidence studies, both as a complement, and an alternative to conventional surveying methods. These studies have demonstrated that high-accuracy GPS techniques are an efficient tool in tracking long-term land subsidence. A great number of Continuously Operating Reference GPS Stations (CORS) have been installed in China during the past five years. Considerable land subsidence has been observed from CORS stations installed in several large cities. This study investigated GPS time series observed at three CORS in Tianjin: TJBD (2010-2014), TJBH (2010-2014), and TJWQ (2010-2014). Tianjin is one of the largest cities that is experiencing severe land subsidence problems in China. The observations at the three GPS sites indicate different subsidence rates. The average subsidence rate over four years are 0.2 cm/year at TJBD, 2 cm/year at TJBH, and 4.4 cm/year at TJWQ. The GPS station TJBD is located at Baodi, Tianjin. This area is the least economically developed and have the smallest population compared to the other two areas. Over 80% of water usage in Baodi is for agriculture and only less than 15% is from groundwater. The rapid subsidence at TJBH and TJWQ were caused by huge groundwater withdrawals associate with rapid urban and industrial developments in Binhai and Wuqing. Wuqing district, with a unique location advantage called "Corridor of Beijing and Tianjin", has been experiencing major urbanization. The population has reached 1,053,300 and the water usage has reached 350 million cubic meters in 2012. Over 25% of water usage is from groundwater. Significant annual and half-annual seasonal ground surface fluctuation has been observed from all three GPS stations. The peak-to-peak amplitude of the annual signal is 1.5 cm.

  5. Growth and subsidence of carbonate platforms: numerical modelling and application to the Dolomites, Italy

    Directory of Open Access Journals (Sweden)

    A. Bosellini

    2004-06-01

    Full Text Available The phenomenon of subsidence induced by the growth of carbonate platforms has been investigated with the aid of numerical modelling. The research aimed to quantify the relative contribution of this process in the creation of the accommodation space required to pile up thick neritic bodies. We analysed two end-member deformation styles, namely the elastic behaviour of the lithosphere when locally loaded and the plastic-like reaction of a sedimentary succession underlying a growing carbonate buildup. The former process, analysed using a modified flexural model, generates a regional subsidence. In contrast, the latter process, simulated by considering the compaction occurring in soft sediments, generates a local subsidence. We attempted to quantify the amount and distribution of subsidence occurring below and surrounding an isolated platform and in the adjacent basin. The major parameters playing a role in the process are discussed in detail. The model is then applied to the Late Anisian-Early Ladinian generation of carbonate platforms of the Dolomites, Northern Italy, where they are spectacularly exposed. Taking also into account the Tertiary shortening that occurred in the area, both local and regional subsidence contributions of major platform bodies have been calculated aimed at a reconstruction of the map of the induced subsidence. A major outcome of this study is that the accommodation space, that allowed the accumulation of very thick shallow-water carbonate successions in the Dolomites, was only partially due to lithospheric stretching while the contribution given by the 'local' overload is as high as 20-40% of the total subsidence. Our results also shed some light on the water-depth problem of the Triassic basins as well as on the basin-depth to platform-thickness relationships.

  6. Numerical modelling of ground-borne noise and vibration in buildings due to surface rail traffic

    Science.gov (United States)

    Fiala, P.; Degrande, G.; Augusztinovicz, F.

    2007-04-01

    This paper deals with the numerical computation of the structural and acoustic response of a building to an incoming wave field generated by high-speed surface railway traffic. The source model consists of a moving vehicle on a longitudinally invariant track, coupled to a layered ground modelled with a boundary element formulation. The receiver model is based on a substructuring formulation and consists of a boundary element model of the soil and a finite element model of the structure. The acoustic response of the building's rooms is computed by means of a spectral finite element formulation. The paper investigates the structural and acoustic response of a multi-story portal frame office building up to a frequency of 150 Hz to the passage of a Thalys high-speed train at constant velocity. The isolation performance of three different vibration countermeasures: a floating-floor, a room-in-room, and base-isolation, are examined.

  7. Second-Order Nonlinearity in Triangular Lattice Perforated Gold Film due to Surface Plasmas Resonance

    Directory of Open Access Journals (Sweden)

    Renlong Zhou

    2014-01-01

    Full Text Available We have studied the excitation second-order nonlinearity through a triangular lattice perforated gold film instead of square lattice in many papers. Under the excitation of surface plasmas resonance effect, the second order nonlinearity exists in the noncentrosymmetric split-ring resonators arrays. Reflection of fundamental frequency wave through a triangular lattice perforated gold film is obtained. We also described the second harmonic conversion efficiencies in the second order nonlinear optical process with the spectra. Moreover, the electric field distributions of fundamental frequency above the gold film region are calculated. The light propagation through the holes results in the enhancement of the second order nonlinearity including second harmonic generation as well as the sum (difference frequency generation.

  8. 高层建筑物荷载与地下水开采叠加作用下的地面沉降特征%CHARACTERISTICS OF LAND SUBSIDENCE DUE TO BOTH HIGH-RISE BUILDING AND EXPLOITATION OF GROUNDWATER IN URBAN AREA

    Institute of Scientific and Technical Information of China (English)

    丁德民; 马凤山; 张亚民; 王杰; 郭捷

    2011-01-01

    在地下水开采和高层建筑荷载叠加作用下,城市地面沉降分布愈加复杂.以天津塘沽地区为例,考虑到土体在固结沉降中的平衡条件、弹性本构条件、变形协调条件和水流连续条件,以比奥固结理论为基础,建立了高层建筑荷载和地下水开采叠加作用下三维地面沉降模型,采用有限元方法进行了数值计算.结果表明,高层建筑物的附加荷载作用在其建成后的3~4a内将产生可观的地面沉降量;抽水和高层建筑荷载叠加作用下的地面沉降存在耦合效应,叠加作用下的地面沉降值小于可比条件下单独抽水和单独荷载作用下地面沉降值之和.%The distribution of land subsidence caused by both high-rise building loading and exploitation of groundwater is increasingly complex in urban area. This paper examines the land subsidence in Tanggu area. It considers the equilibrium condition, the elastic constitutive condition, the deformation compatibility condition of solid, and the continuity condition of water flow in soil consolidation. It then develops a three-dimensional land subsidence model for Tanggu area. The model is also based on the Biot's consolidation theory and takes into account both high-rise building loading and exploitation of groundwater. The finite element method is applied to the numerical calculation of the ground subsidence. The results indicate that there will be a considerable ground settlement in 3 ~ 4 years after construction of high-rise building. The settlement under the condition of both high-rise building loading and the exploitation of groundwater is lower than the sum settlement under he two single conditions. The model has a good convergence property and its computing results conform to actual data well.

  9. Subsidizing purchase of apartments and residential construction

    Directory of Open Access Journals (Sweden)

    Baturan Luka

    2012-01-01

    Full Text Available During last few years, Republic of Serbia has been allowing significant resources for subsidizing purchase of apartments and residential construction. Explanation for this is desire to help construction sector to overcome consequences of economic crisis, as well as social categories to solve housing issue. The paper analyzes economic consequences, benefits and costs of conducting this economic policy, as well as reasons leading to its establishment.

  10. Regional Sea Level Variation: California Coastal Subsidence (Invited)

    Science.gov (United States)

    Blewitt, G.; Hammond, W. C.; Nerem, R.

    2013-12-01

    Satellite altimetry over the last two decades has measured variations in geocentric sea level (GSL), relative to the Earth system center of mass, providing valuable data to test models of physical oceanography and the effects of global climate change. The societal impacts of sea level change however relate to variations in local sea level (LSL), relative to the land at the coast. Therefore, assessing the impacts of sea level change requires coastal measurements of vertical land motion (VLM). Indeed, ΔLSL = ΔGSL - ΔVLM, with subsidence mapping 1:1 into LSL. Measurements of secular coastal VLM also allow tide-gauge data to test models of GSL over the last century in some locations, which cannot be provided by satellite data. Here we use GPS geodetic data within 15 km of the US west coast to infer regional, secular VLM. A total of 89 GPS stations met the criteria that time series span >4.5 yr, and do not have obvious non-linear variation, as may be caused by local instability. VLM rates for the GPS stations are derived in the secular reference frame ITRF2008, which aligns with the Earth system center of mass to ×0.5 mm/yr. We find that regional VLM has different behavior north and south of the Mendocino Triple Junction (MTJ). The California coast has a coherent regional pattern of subsidence averaging 0.5 mm/yr, with an increasing trend to the north. This trend generally matches GIA model predictions. Around San Francisco Bay, the observed coastal subsidence of 1.0 mm/yr coherently decreases moving away from the Pacific Ocean to very small subsidence on the east shores of the bay. This gradient is likely caused by San Andreas-Hayward Fault tectonics, and possibly by differential surface loading across the bay and Sacramento-San Joachim River Delta. Thus in addition to the trend in subsidence from GIA going northward along the California coast, tectonics may also play a role where the plate boundary fault system approaches the coast. In contrast, we find that VLM

  11. Oral Morbidity in the Subsidized Population of Manizales Served through the TeachingService Model at a University Clinic

    OpenAIRE

    de la Rosa-Marrugo, Eola; Avilés-Franco, Paula; Rodríguez-Lezama, Didier

    2014-01-01

    Introduction: the purpose of this research was to determine oral morbidity in the subsidized population of Manizales served through the teaching-service model at a university clinic. Materials and methods: the descriptive study looked at a study population of 122 patients of all ages affiliated with the subsidized system. Sociodemographic, systemic precedents and oral alterations were analyzed, such as changes in the dental, gingival and periodontal surfaces, occlusion, pulp, periapical bones...

  12. Neotectonic of subsiding basins : case of studies from Marañon and Beni basins, Peru and Bolivia

    OpenAIRE

    Dumont, Jean-Francois

    1994-01-01

    Climatic conditions make the fluvial processes very sensitive in the extended flood plain of subandean basins, giving typical morphostructures. Because of high subsidence rate, these basins are case for the understanding of neotectonics in subsiding basins. Recent anciente fluvial traces are used in combination with sub surface structures, neotectonic and seismotectonic data to study the neotectonic evolution of the Peruvian and Bolivian active foreland basins. These basins, the Marañon Basin...

  13. Subsidence Induced Faulting Hazard Zonation Using Persistent Scatterer Interferometry and Horizontal Gradient Mapping in Mexican Urban Areas

    Science.gov (United States)

    Cabral-Cano, E.; Cigna, F.; Osmanoglu, B.; Dixon, T.; Wdowinski, S.

    2011-12-01

    Subsidence and faulting have affected Mexico city for more than a century and the process is becoming widespread throughout larger urban areas in central Mexico. This process causes substantial damages to the urban infrastructure and housing structures and will certainly become a major factor to be considered when planning urban development, land use zoning and hazard mitigation strategies in the next decades. Subsidence is usually associated with aggressive groundwater extraction rates and a general decrease of aquifer static level that promotes soil consolidation, deformation and ultimately, surface faulting. However, local stratigraphic and structural conditions also play an important role in the development and extension of faults. In all studied cases stratigraphy of the uppermost sediment strata and the structure of the underlying volcanic rocks impose a much different subsidence pattern which is most suitable for imaging through satellite geodetic techniques. We present examples from several cities in central Mexico: a) Mexico-Chalco. Very high rates of subsidence, up to 370 mm/yr are observed within this lacustrine environment surrounded by Pliocene-Quaternary volcanic structures. b) Aguascalientes where rates up to 90 mm/yr in the past decade are observed, is controlled by a stair stepped N-S trending graben that induces nucleation of faults along the edges of contrasting sediment package thicknesses. c) Morelia presents subsidence rates as high as 80 mm/yr. Differential deformation is observed across major basin-bounding E-W trending faults and with higher subsidence rates on their hanging walls, where the thickest sequences of compressible Quaternary sediments crop out. Our subsidence and faulting study in urban areas of central Mexico is based on a horizontal gradient analysis using displacement maps from Persistent Scatterer InSAR that allows definition of areas with high vulnerability to surface faulting. Correlation of the surface subsidence pattern

  14. Using Persistent Scatterers Interferometry to create a subsidence map of the Nile Delta in Egypt

    Science.gov (United States)

    Bouali, E. Y.; Sultan, M.; Becker, R.; Cherif, O.

    2013-12-01

    Inhabitants of the Nile Delta in Egypt, especially those who live around the coast, are threatened by two perpetual hazards: (1) sea level rise and encroachment from the Mediterranean Sea and (2) land subsidence that is inherent in deltaic environments. With cities like Alexandria and Port Said currently only one meter above sea level, it is important to understand the nature of the sea level rise and land subsidence, both spatially and temporally, and to be able to quantify these hazards. The magnitude of sea level rise has been actively monitored in stations across the Mediterranean Sea; the subsidence of the Nile Delta, as a whole system however, has not been adequately quantified. We have employed the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique known as Persistent Scatterers Interferometry (PSI) across the entire northern parts of the Nile Delta. A dataset of 106 ENVISAT single look complex (SLC) scenes (four descending tracks: 164, 207, 436, and 479) acquired throughout the time period 2003 to 2010 were obtained from the European Space Agency and utilized for radar interferometric purposes. Multiple combinations of these scenes - used for output optimization and validation - were processed. Due to the nature of the PSI technique, subsidence rates calculated using this technique are values measured from cities and urban areas - where PSI works well. The methodology of choice is to calculate the subsidence rates on a city-by-city basis by: (1) choosing an urban area and cutting the SLC scene stack down to a small area (25 - 200 km2); (2) processing this area multiple times using difference scene and parameter combinations in order to best optimize persistent scatterer (PS) abundance and ground displacement measurements; (3) calibrating the relative ground motion measured by PSI to known locations of minimal subsidence rates. The final result is a spatial representation of the subsidence rates across the Nile Delta in Egypt. Measured

  15. Monitoring land subsidence process in the urban area of Ho Chi Minh city, Vietnam using multi-temporal SAR Interferometry

    Science.gov (United States)

    Nguyen, Xuan; Chang, Chung-Pai; Le, Tuan

    2016-04-01

    Land subsidence has become the most common hazard in urban area that could led to cracking buildings and infrastructures, extending the flooding area or even change the river path. Despite deriving precise information, conventional subsidence monitoring techniques are considered as costly, man-power consuming and lack of comprehensive information. Recently, SAR Interferometry (InSAR) has become a widely used geodetic technique for monitoring the deformation of the Earth's surface, especially methods based on the use of a multi-temporal dataset. In this study, we use a stack of 18 SAR images acquired from L-band PALSAR sensor onboard the ALOS satellite to derive the subsidence information of Ho Chi Minh city, Vietnam over the period of December 2006 to December 2010. The Stanford Method for Persistent Scatterers (StaMPS) Multi-Temporal Interferometry (MTI) approach is chosen to take advantages of both the persistent scatterers and the distributed scatterers, which could be used as monitoring points to measure the subsidence process. Assume the subsidence in this area mostly corresponds to vertical components, we found subsidence patterns along Saigon river and in the South of the city. Maximum subsidence rate reaches up to -66 mm/year in vertical direction. Finally, InSAR derived result and previous levelling data are taken into comparison to find the correlation between the two results.

  16. BasinVis 1.0: A MATLAB®-based program for sedimentary basin subsidence analysis and visualization

    Science.gov (United States)

    Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

    2016-06-01

    Stratigraphic and structural mapping is important to understand the internal structure of sedimentary basins. Subsidence analysis provides significant insights for basin evolution. We designed a new software package to process and visualize stratigraphic setting and subsidence evolution of sedimentary basins from well data. BasinVis 1.0 is implemented in MATLAB®, a multi-paradigm numerical computing environment, and employs two numerical methods: interpolation and subsidence analysis. Five different interpolation methods (linear, natural, cubic spline, Kriging, and thin-plate spline) are provided in this program for surface modeling. The subsidence analysis consists of decompaction and backstripping techniques. BasinVis 1.0 incorporates five main processing steps; (1) setup (study area and stratigraphic units), (2) loading well data, (3) stratigraphic setting visualization, (4) subsidence parameter input, and (5) subsidence analysis and visualization. For in-depth analysis, our software provides cross-section and dip-slip fault backstripping tools. The graphical user interface guides users through the workflow and provides tools to analyze and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the results using the full range of available plot options in MATLAB. We demonstrate all functions in a case study of Miocene sediment in the central Vienna Basin.

  17. Magnitude and extent of land subsidence in central Mexico revealed by regional InSAR ALOS time-series survey

    Science.gov (United States)

    Chaussard, E.; Wdowinski, S.; Amelung, F.; Cabral-Cano, E.

    2013-05-01

    Massive groundwater extraction is very common in Mexico and is well known to result in land subsidence. However, most surveys dedicated to land subsidence focus on one single city, mainly Mexico City, and thus fail to provide a comprehensive picture of the problem. Here we use a space-based radar remote sensing technique, known as Interferometric Synthetic Aperture Radar (InSAR) to detect land subsidence in the entire central Mexico area. We used data from the Japanese satellite ALOS, processed over 600 SAR images acquired between 2007-2011 and produced over 3000 interferograms to cover and area of 200,000 km2 in central Mexico. We identify land subsidence in twenty-one areas, including seventeen cities, namely from east to west, Puebla, Mexico city, Toluca de Lerdo, Queretaro, San Luis de la Paz, south of San Luis de la Paz, Celaya, south of Villa de Reyes, San Luis Potosi, west of Villa de Arista, Morelia, Salamanca, Irapuato, Silao, Leon, Aguascalientes, north of Aguascalientes, Zamora de Hidalgo, Guadalajara, Ahuacatlan, and Tepic. Subsidence rates of 30 cm/yr are observed in Mexico City, while in the other locations typical rates of 5-10 cm/yr are noticed. Regional surveys of this type are necessary for the development of hazard mitigation plans and efficient use of ground-based monitoring. We additionally correlate subsidence with land use, surface geology, and faults distribution and suggest that groundwater extraction for agricultural, urban, and industrial uses are the main causes of land subsidence. We also reveal that the limits of the subsiding areas often correlate with existing faults, motion on these faults being driven by water extraction rather than by tectonic activity. In all the subsiding locations we observe high ground velocity gradients emphasizing the significant risks associated with land subsidence in central Mexico. Averaged 2007-2011 ground velocity map from ALOS InSAR time-series in central Mexico, revealing land subsidence in 21

  18. Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960-2014

    Science.gov (United States)

    Kuipers Munneke, P.; Ligtenberg, S. R. M.; Noël, B. P. Y.; Howat, I. M.; Box, J. E.; Mosley-Thompson, E.; McConnell, J. R.; Steffen, K.; Harper, J. T.; Das, S. B.; van den Broeke, M. R.

    2015-11-01

    Observed changes in the surface elevation of the Greenland Ice Sheet are caused by ice dynamics, basal elevation change, basal melt, surface mass balance (SMB) variability, and by compaction of the overlying firn. The last two contributions are quantified here using a firn model that includes compaction, meltwater percolation, and refreezing. The model is forced with surface mass fluxes and temperature from a regional climate model for the period 1960-2014. The model results agree with observations of surface density, density profiles from 62 firn cores, and altimetric observations from regions where ice-dynamical surface height changes are likely small. In areas with strong surface melt, the firn model overestimates density. We find that the firn layer in the high interior is generally thickening slowly (1-5 cm yr-1). In the percolation and ablation areas, firn and SMB processes account for a surface elevation lowering of up to 20-50 cm yr-1. Most of this firn-induced marginal thinning is caused by an increase in melt since the mid-1990s and partly compensated by an increase in the accumulation of fresh snow around most of the ice sheet. The total firn and ice volume change between 1980 and 2014 is estimated at -3295 ± 1030 km3 due to firn and SMB changes, corresponding to an ice-sheet average thinning of 1.96 ± 0.61 m. Most of this volume decrease occurred after 1995. The computed changes in surface elevation can be used to partition altimetrically observed volume change into surface mass balance and ice-dynamically related mass changes.

  19. Instrumentation plan for characterization of subsidence over longwall mining panels at Allen Mine, Weston, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    O' Rourke, J.

    1980-01-01

    The program includes surface, subsurface, and mine-level instrumentation to monitor subsidence characteristics over two adjacent longwall mining panels, situated in mountainous topography in southern Colorado. An installation plan has been detailed to show numbers and arrangements of instruments in and over the panels, and includes pertinent installation details. The appendix contains technical descriptions of standard features of some of the instrument systems, though in certain cases standard instruments will be modified by Woodward-Clyde Consultants (WCC) or the manufacturer to suit site specific installation requirements detailed on attached drawings. Technical discussions on the application of the instrument arrangements and data monitored to subsidence modeling are given in the report.

  20. Application of synthetic aperture radar interferometry for mine subsidence monitoring in the western United States

    Science.gov (United States)

    Wempen, Jessica Michelle

    Differential Interferometric Synthetic Aperture Radar (DInSAR), a satellite-based remote sensing technique, is a practical method for measuring deformation of the earth's surface. In this investigation, the application of DInSAR for monitoring mine subsidence was evaluated for active underground mining regions in the Green River Basin in southwest Wyoming and the Wasatch Plateau in central Utah. Interferograms were generated using X-band (3-cm wavelength) Synthetic Aperture Radar data from the TerraSAR-X mission and L-band (24-cm wavelength) Synthetic Aperture Radar data from the Advanced Land Observing Satellite. In general, the DInSAR data have high spatial and temporal resolutions and show gradual, progressive subsidence. In the Green River Basin, displacements were estimated using both L-band and X-band data. In the Wasatch Plateau, displacements were only estimated using L-band data; areas affected by subsidence are identifiable in the X-band data, but precisely quantifying subsidence magnitudes is difficult as a result of significant phase noise. In the Green River Basin, the maximum subsidence magnitude was 150 cm over 690 days, estimated using L-band DInSAR. In the Wasatch Plateau, the maximum subsidence magnitude was 180 cm over 414 days. In both regions, as a result of low coherence in the areas with large displacements, the maximum displacements may be underestimated by tens of centimeters. Additionally, relationships between surface deformations measured by DInSAR and mining-induced seismicity (MIS) in the Green River Basin and the Wasatch Plateau were explored. Both regions exhibit large magnitude, relatively rapid subsidence, but the characteristics (rates and magnitudes) of MIS in the Wasatch Plateau study region and the Green River Basin are significantly different. In the Wasatch Plateau study region, surface displacements tend to precede seismicity, event rates tend to be high, and event magnitudes tend to be relatively low. In the Green River

  1. New information on regional subsidence and soil fracturing in Mexico City Valley

    Science.gov (United States)

    Auvinet, G.; Méndez-Sánchez, E.; Juárez-Camarena, M.

    2015-11-01

    In this paper, updated information about regional subsidence in Mexico City downtown area is presented. Data obtained by R. Gayol in 1891, are compared with information obtained recently from surveys using the reference points of Sistema de Aguas de la Ciudad de México (2008) and on the elevation of a cloud of points on the ground surface determined using Light Detection and Ranging (LiDAR) technology. In addition, this paper provides an overview of recent data obtained from systematic studies focused on understanding soil fracturing associated with regional land subsidence and mapping of areas susceptible to cracking in Mexico City Valley.

  2. Enhanced spin Seebeck effect signal due to spin-momentum locked topological surface states

    Science.gov (United States)

    Jiang, Zilong; Chang, Cui-Zu; Masir, Massoud Ramezani; Tang, Chi; Xu, Yadong; Moodera, Jagadeesh S.; MacDonald, Allan H.; Shi, Jing

    2016-05-01

    Spin-momentum locking in protected surface states enables efficient electrical detection of magnon decay at a magnetic-insulator/topological-insulator heterojunction. Here we demonstrate this property using the spin Seebeck effect (SSE), that is, measuring the transverse thermoelectric response to a temperature gradient across a thin film of yttrium iron garnet, an insulating ferrimagnet, and forming a heterojunction with (BixSb1-x)2Te3, a topological insulator. The non-equilibrium magnon population established at the interface can decay in part by interactions of magnons with electrons near the Fermi energy of the topological insulator. When this decay channel is made active by tuning (BixSb1-x)2Te3 into a bulk insulator, a large electromotive force emerges in the direction perpendicular to the in-plane magnetization of yttrium iron garnet. The enhanced, tunable SSE which occurs when the Fermi level lies in the bulk gap offers unique advantages over the usual SSE in metals and therefore opens up exciting possibilities in spintronics.

  3. Modeling nonlinear errors in surface electromyography due to baseline noise: a new methodology.

    Science.gov (United States)

    Law, Laura Frey; Krishnan, Chandramouli; Avin, Keith

    2011-01-01

    The surface electromyographic (EMG) signal is often contaminated by some degree of baseline noise. It is customary for scientists to subtract baseline noise from the measured EMG signal prior to further analyses based on the assumption that baseline noise adds linearly to the observed EMG signal. The stochastic nature of both the baseline and EMG signal, however, may invalidate this assumption. Alternately, "true" EMG signals may be either minimally or nonlinearly affected by baseline noise. This information is particularly relevant at low contraction intensities when signal-to-noise ratios (SNR) may be lowest. Thus, the purpose of this simulation study was to investigate the influence of varying levels of baseline noise (approximately 2-40% maximum EMG amplitude) on mean EMG burst amplitude and to assess the best means to account for signal noise. The simulations indicated baseline noise had minimal effects on mean EMG activity for maximum contractions, but increased nonlinearly with increasing noise levels and decreasing signal amplitudes. Thus, the simple baseline noise subtraction resulted in substantial error when estimating mean activity during low intensity EMG bursts. Conversely, correcting EMG signal as a nonlinear function of both baseline and measured signal amplitude provided highly accurate estimates of EMG amplitude. This novel nonlinear error modeling approach has potential implications for EMG signal processing, particularly when assessing co-activation of antagonist muscles or small amplitude contractions where the SNR can be low.

  4. The change in mutagenicity:study on surface water of Qiantang River due to tide

    Institute of Scientific and Technical Information of China (English)

    WuNX; YangYM

    2002-01-01

    The Qiangtang River lies in Zhejiang Province of China.In this study,the genotoxicity of surface water samples from five sites along the river were detected using Ames test(TA98,TA100±S9),comet(SCGE) test and cytokinesis-block micronucleus(CBMN) tesdt(-S9) in the human peripheral lymphocytes in vitro.The results indicated that in upstream samples (first site) during falling-tide was found slight mutagenicity in TA98 strain with S9 and without S9.The mutagenicity of samples from the second to the fifth site was gradually stronger.Except the first site sample,the micronucleated cell rates of the other four samples during falling-tide significantly increased in CBMN test,and the extent of migration of DNA fragments of the four samples was found to be significantly different from control group.In the upstream(first site) samples during flow-tide were found no mutagen by three short-term tests.But the other four samples were found more stronger mutagenicity in TA98 strain with S9 than that during falling-tide.The micronucleated cell rates and the extent of migration of DNA fragments of the samples were sdignificantly high than that during falling-tide too.

  5. Colour and chemical changes of the lime wood surface due to CO2 laser thermal modification

    Science.gov (United States)

    Kubovský, Ivan; Kačík, František

    2014-12-01

    We studied colour and main wood components changes of lime wood caused by CO2 laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO2 laser beam (wavelength of 10.6 μm) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm-2) lightness (ΔL*) decrease and increase of the total colour difference (ΔE*) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

  6. Assessment of pot-hole subsidence risk for Indian coal mines

    Institute of Scientific and Technical Information of China (English)

    Lokhande D. Ritesh; Murthy Vemavarapu M.S.R.; Vellanky Venkateswarlu; Singh B. Kalendra

    2015-01-01

    Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence. Pot-hole subsidence is extremely hazardous and does not give any prior indication before its occurrence. In India, several pot-holes have occurred in the coal mines of South Eastern Coalfields Limited triggering the need for in-depth studies. In line with the requirement, literature review and field investigations were conducted to develop an in-depth under-standing of various parameters influencing the occurrence of pot-holes. The critical parameters identified were rock to soil ratio, depth to height of extraction ratio, brittleness index of rock and rock density. Risk assessment of pot-hole subsidence has been done by developing an empirical rating approach named as pot-hole subsidence rating (PHSR), involving the critical parameters with suitable corrections for certain structural and mining conditions to obtain corrected PHSR (CPHSR). CPHSR was then applied for all the 34 pot-holes studied and it was found that all the pot-holes fall under Class I and Class II category of risk representing a very high to high risk class. An effort was made for the estimation of pot-hole depth uti-lizing the developed CPHSR in both the development and depillaring cases. The developed approach was found to yield consistent results in pot-hole depth prediction.

  7. Modeling viscoelastic deformation of the earth due to surface loading by commercial finite element package - ABAQUS

    Science.gov (United States)

    Kit Wong, Ching; Wu, Patrick

    2017-04-01

    Wu (2004) developed a transformation scheme to model viscoelatic deformation due to glacial loading by commercial finite element package - ABAQUS. Benchmark tests confirmed that this method works extremely well on incompressible earth model. Bangtsson & Lund (2008),however, showed that the transformation scheme would lead to incorrect results if compressible material parameters are used. Their study implies that Wu's method of stress transformation is inadequate to model the load induced deformation of a compressible earth under the framework of ABAQUS. In light of this, numerical experiments are carried out to find if there exist other methods that serve this purpose. All the tested methods are not satisfying as the results failed to converge through iterations, except at the elastic limit. Those tested methods will be outlined and the results will be presented. Possible reasons of failure will also be discussed. Bängtsson, E., & Lund, B. (2008). A comparison between two solution techniques to solve the equations of glacially induced deformation of an elastic Earth. International journal for numerical methods in engineering, 75(4), 479-502. Wu, P. (2004). Using commercial finite element packages for the study of earth deformations, sea levels and the state of stress. Geophysical Journal International, 158(2), 401-408.

  8. Contribution of Sediment Compaction/Loading to the Ganges-Bangladesh Delta Subsidence

    Science.gov (United States)

    Karpytchev, Mikhail; Krien, Yann; Ballu, Valerie; Becker, Melanie; Calmant, Stephane; Spada, Giorgio; Guo, Junyi; Khan, Zahirul; Shum, Ck

    2016-04-01

    A pronounced spatial variability characterizes the subsidence/uplift rates in the Ganges-Bangladesh delta estimated from both sediment cores and modern geodetic techniques. The large variability of the subsidence rates suggests an interplay of different natural and anthropogenic processes including tectonics, sediment loading and sediment compaction, groundwater extaction among many others drivers of the delta vertical land movements.In this study, we focus on estimating the subsidence rates due to the sediments transported by the Ganges-Brahmaputra since the last 18 000 years. The delta subsidence induced by the sediment loading and the resulting sea level changes are modelled by the TABOO and SELEN software (Spada, 2003; Stocchi and Spada, 2007) in the framework of a gravitationally self-consistent Earth model. The loading history was obtained from available sediment cores and from the isopach map of Goodbread and Kuehl (2000). The results demonstrate that the delta loading enhanced by the Holocene sedimention can be responsable for a regular subsidence across the Ganges-Brahmaputra delta with an amplitude of 1-5 mm/yr along the Bengal coast. These estimates demonstrate that the contribution of the Holocene as well as modern sediment loading should be taken into account in climate change mitigation politicy for Bangladesh.

  9. Effects of Active Subsidence Vs. Existing Basin Geometry on Fluviodeltaic Channels and Stratal Architecture

    Science.gov (United States)

    Liang, M.; Kim, W.; Passalacqua, P.

    2015-12-01

    Tectonic subsidence and basin topography, both determining the accommodation, are fundamental controls on the basin filling processes. Their effects on the fluvial organization and the resultant subsurface patterns remain difficult to predict due to the lack of understanding about interaction between internal dynamics and external controls. Despite the intensive studies on tectonic steering effects on alluvial architecture, how the self-organization of deltaic channels, especially the distributary channel network, respond to tectonics and basin geometry is mostly unknown. Recently physical experiments and field studies have hinted dramatic differences in fluviodeltaic evolution between ones associated with active differential subsidence and existing basin depth. In this work we designed a series of numerical experiments using a reduced-complexity channel-resolving model for delta formation, and tested over a range of localized subsidence rates and topographic depression in basin geometry. We also used a set of robust delta metrics to analyze: i) shoreline planform asymmetry, ii) channel and lobe geometry, iii) channel network pattern, iv) autogenic timescales, and v) subsurface structure. The modeling results show that given a similar final thickness, active subsidence enhances channel branching with smaller channel sand bodies that are both laterally and vertically connected, whereas existing topographic depression causes more large-scale channel avulsions with larger channel sand bodies. In general, both subsidence and existing basin geometry could steer channels and/or lock channels in place but develop distinct channel patterns and thus stratal architecture.

  10. Subsidence Detection Using InSAR and Geodetic Measurements in the North-West of Iran

    Science.gov (United States)

    Sedighi, Morteza

    2010-05-01

    The subsidence of the Earth surface is a phenomenon that occurs in some places in the world which overuse underground sources of water. As Iran has semi-arid and arid climate and the rate of rainfall is lower than the mean rate in the world then nowadays we are encountered by over-exploitation of groundwater in agricultural areas and also for extending the cities and industrial areas. Geodetic measurements i.e., repeated leveling measurements of first order leveling network of Iran and continuous GPS measurements of Iranian Permanent GPS Network of Iran (IPGN), showed that there are subsidence areas in the north-west of Iran. In this paper we try to find the area and rate of subsidence in the north-west of Iran using InSAR and geodetic techniques. The result of InSAR technique shows a better understanding on this phenomenon in these areas and has a good consistency with accurate geodetic measurements.

  11. Numerical Modeling of Surface Deformation due to Magma Chamber Inflation/Deflation in a Heterogeneous Viscoelastic Half-space

    Science.gov (United States)

    Dichter, M.; Roy, M.

    2015-12-01

    Interpreting surface deformation patterns in terms of deeper processes in regions of active magmatism is challenging and inherently non-unique. This study focuses on interpreting the unusual sombrero-shaped pattern of surface deformation in the Altiplano Puna region of South America, which has previously been modeled as the effect of an upwelling diapir of material in the lower crust. Our goal is to investigate other possible interpretations of the surface deformation feature using a suite of viscoelastic models with varying material heterogeneity. We use the finite-element code PyLith to study surface deformation due to a buried time-varying (periodic) overpressure source, a magma body, at depth within a viscoelastic half-space. In our models, the magma-body is a penny-shaped crack, with a cylindrical region above the crack that is weak relative to the surrounding material. We initially consider a magma body within a homogeneous viscoelastic half-space to determine the effect of the free surface upon deformation above and beneath the source region. We observe a complex depth-dependent phase relationship between stress and strain for elements that fall between the ground surface and the roof of the magma body. Next, we consider a volume of weak material (faster relaxation time relative to background) that is distributed with varying geometry around the magma body. We investigate how surface deformation is governed by the spatial distribution of the weak material and its rheologic parameters. We are able to reproduce a "sombrero" pattern of surface velocities for a range of models with material heterogeneity. The wavelength of the sombrero pattern is primarily controlled by the extent of the heterogeneous region, modulated by flexural effects. Our results also suggest an "optimum overpressure forcing frequency" where the lifetime of the sombrero pattern (a transient phenomenon due to the periodic nature of the overpressure forcing) reaches a maximum. Through further

  12. Chesapeake Bay subsidence monitored as wetlands loss continues

    Science.gov (United States)

    Nerem, R. S.; van Dam, T. M.; Schenewerk, M. S.

    Fragile wetland ecosystems, which support an abundance of wildlife, are being lost around the Chesapeake Bay at an alarming rate due to an increase in sea level. For example, one third of the total area of the Blackwater National Wildlife Refuge (Figure 1) (approximately 20 km2) was lost between 1938 and 1979 [Leatherman, 1992]. Approximately 4,100 km2 of the perimeter of the Chesapeake Bay are covered by wetlands of which 58% forested wetlands and 28% are salt marshes. It is likely that many factors are responsible for the wetlands loss, some that have global implications, and some that reflect local phenomena.Understanding the mechanisms responsible for wetlands deterioration and loss, however, has been impeded by the lack of adequate data including quantitative monitoring of the types and distribution of flora, Tthe boundaries of specific habitat types, and data on the spatial variations in sea level and land subsidence. This article focuses on the latter problem, which is to determine the relative roles of sea level rise and land subsidence in the region. Over the past four years, a small network of Global Positioning System (GPS) receivers have been installed near tide gauges in the Chesapeake Bay to help determine the cause of relative sea level rise in this region. These receivers are just beginning to yield results.

  13. Residual subsidence analysis after the end of coal mine work. Example from Lorraine Colliery, France

    Energy Technology Data Exchange (ETDEWEB)

    Al Heib, M. [INERIS LAEGO - Ecole Nationale Superieure des Mines de Nancy, 54 - Nancy (France); Nicolas, M.; Noirel, J.F. [Charbonnage de France, 57 - Freyming-Merlebach (France); Wojtkowiak, F

    2005-07-01

    This paper describes the residual movements associated with the deep coal mines. The studied case relates to works located into Lorraine coal basin. The paper is divided into two sections. The first one describes subsidence phenomena, especially the residual phase in terms of amplitude, duration and localization. The second one focus on Morsbach case: the total and residual subsidence measurements will be analyzed and compared to the state of the art as well as the currant knowledge. The results of the analysis show that the duration of residual movements does not exceed 24 months and their amplitude is about 5% of total subsidence. We analyze also the declarations of the mining damage during and after the mining period. Damages occur, after this period are probably due to late observations. (authors)

  14. Elevation change of the Greenland ice sheet due to surface mass balance and firn processes, 1960-2013

    Science.gov (United States)

    Kuipers Munneke, P.; Ligtenberg, S. R. M.; Noël, B. P. Y.; Howat, I. M.; Box, J. E.; Mosley-Thompson, E.; McConnell, J. R.; Steffen, K.; Harper, J. T.; Das, S. B.; van den Broeke, M. R.

    2015-06-01

    Observed changes in the surface elevation of the Greenland ice sheet are caused by ice dynamics, basal elevation change, surface mass balance (SMB) variability, and by compaction of the overlying firn. The latter two contributions are quantified here using a firn model that includes compaction, meltwater percolation, and refreezing. The model is forced with surface mass fluxes and temperature from a regional climate model for the period 1960-2013. The model results agree with observations of surface density, density profiles from 62 firn cores, and altimetric observations from regions where ice-dynamical surface height changes are likely small. We find that the firn layer in the high interior is generally thickening slowly (1-5 cm yr-1). In the percolation and ablation areas, firn and SMB processes account for a surface elevation lowering of up to 20-50 cm yr-1. Most of this firn-induced marginal thinning is caused by an increase in melt since the mid-1990s, and partly compensated by an increase in the accumulation of fresh snow around most of the ice sheet. The total firn and ice volume change between 1980 and 2013 is estimated at -3900 ± 1030 km3 due to firn and SMB, corresponding to an ice-sheet average thinning of 2.32 ± 0.61 m. Most of this volume decrease occurred after 1995. The computed changes in surface elevation can be used to partition altimetrically observed volume change into surface mass balance and ice-dynamically related mass changes.

  15. Detecting land subsidence near metro lines in the Baoshan district of Shanghai with multi-temporal interferometric synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    Tao Li; Guoxiang Liu; Hui Lin; Rui Zhang; Hongguo Jia; Bing Yu

    2014-01-01

    Land subsidence is a major factor that affects metro line (ML) stability. In this study, an improved multi-temporal interferometric synthetic aperture radar (InSAR) (MTI) method to detect land subsidence near MLs is pre-sented. In particular, our multi-temporal InSAR method provides surface subsidence measurements with high observation density. The MTI method tracks both point-like targets and distributed targets with temporal radar back-scattering steadiness. First, subsidence rates at the point targets with low-amplitude dispersion index (ADI) values are extracted by applying a least-squared estimator on an optimized freely connected network. Second, to reduce error propagation, the pixels with high-ADI values are classified into several groups according to ADI intervals and processed using a Pearson correlation coefficient and hierarchical analysis strategy to obtain the distributed targets. Then, nonlinear subsidence components at all point-like and dis-tributed targets are estimated using phase unwrapping and spatiotemporal filtering on the phase residuals. The proposed MTI method was applied to detect land subsidence near MLs of No. 1 and 3 in the Baoshan district of Shanghai using 18 TerraSAR-X images acquired between April 21, 2008 and October 30, 2010. The results show that the mean subsidence rates of the stations distributed along the two MLs are -12.9 and -14.0 mm/year. Furthermore, three subsidence funnels near the MLs are discovered through the hierarchical analysis. The testing results demonstrate the satisfactory capacity of the proposed MTI method in pro-viding detailed subsidence information near MLs.

  16. Polyphase tectonic subsidence evolution of the Vienna Basin inferred from quantitative subsidence analysis of the northern and central parts

    Science.gov (United States)

    Lee, Eun Young; Wagreich, Michael

    2016-04-01

    The Vienna Basin is a tectonically complex Neogene basin situated at the Alpine-Carpathian transition. This study analyzes a detailed quantification of subsidence in the northern and central parts of the Vienna Basin to understand its tectonic subsidence evolution. About 200 wells were used to arrange stratigraphic setting, and wells reaching the pre-Neogene basement were analyzed for subsidence. To enhance the understanding of the regional subsidences, the wells were sorted into ten groups based on their position on major fault blocks. In the Early Miocene, subsidence was slow and along E-W to NE-SW trending axis, indicating the development of thrust-controlled piggyback basins. During the late Early Miocene data show abruptly increasing subsidence, making the initiation of the Vienna pull-apart basin system. From the Middle Miocene, the tectonic subsidence curves show regionally different patterns. The tectonic subsidence during the Middle Miocene varies laterally across the Vienna Basin, and the differential subsidence can be related to the changing tensional regime of weakening transtension and strengthening extension toward the late Middle Miocene. From the late Middle Miocene to the Late Miocene, the tectonic subsidence occurred dominantly along the regional active faults, and corresponds to the axis of E-W trending extension of the western parts of the Pannonian Basin system. In the Quaternary the Vienna Basin has been reactivated, and resulted in subsidence along the NE-SW trending Vienna Basin transfer fault system.

  17. Investigation of correlation of the variations in land subsidence (detected by continuous GPS measurements and methodological data in the surrounding areas of Lake Urmia

    Directory of Open Access Journals (Sweden)

    K. Moghtased-Azar

    2012-11-01

    Full Text Available Lake Urmia, a salt lake in the north-west of Iran, plays a valuable role in the environment, wildlife and economy of Iran and the region, but now faces great challenges for survival. The Lake is in immediate and great danger and is rapidly going to become barren desert. As a result, the increasing demands upon groundwater resources due to expanding metropolitan and agricultural areas are a serious challenge in the surrounding regions of Lake Urmia. The continuous GPS measurements around the lake illustrate significant subsidence rate between 2005 and 2009. The objective of this study was to detect and specify the non-linear correlation of land subsidence and temperature activities in the region from 2005 to 2009. For this purpose, the cross wavelet transform (XWT was carried out between the two types of time series, namely vertical components of GPS measurements and daily temperature time series. The significant common patterns are illustrated in the high period bands from 180–218 days band (~6–7 months from September 2007 to February 2009. Consequently, the satellite altimetry data confirmed that the maximum rate of linear trend of water variation in the lake from 2005 to 2009, is associated with time interval from September 2007 to February 2009. This event was detected by XWT as a critical interval to be holding the strong correlation between the land subsidence phenomena and surface temperature. Eventually the analysis can be used for modeling and prediction purposes and probably stave off the damage from subsidence phenomena.

  18. Effects of anthropogenic land-subsidence on inundation dynamics: the case study of Ravenna, Italy

    Science.gov (United States)

    Carisi, Francesca; Domeneghetti, Alessio; Castellarin, Attilio

    2016-05-01

    Can differential land-subsidence significantly alter river flooding dynamics, and thus flood risk in flood prone areas? Many studies show how the lowering of the coastal areas is closely related to an increase in the flood-hazard due to more important tidal flooding and see level rise. The literature on the relationship between differential land-subsidence and possible alterations to riverine flood-hazard of inland areas is still sparse, although several geographical areas characterized by significant land-subsidence rates during the last 50 years experienced intensification in both inundation magnitude and frequency. We investigate the possible impact of a significant differential ground lowering on flood hazard over a 77 km2 area around the city of Ravenna, in Italy. The rate of land-subsidence in the study area, naturally in the order of a few mm year-1, dramatically increased up to 110 mm year-1 after World War II, primarily due to groundwater pumping and gas production platforms. The result was a cumulative drop that locally exceeds 1.5 m. Using a recent digital elevation model (res. 5 m) and literature data on land-subsidence, we constructed a ground elevation model over the study area in 1897 and we characterized either the current and the historical DEM with or without road embankments and land-reclamation channels in their current configuration. We then considered these four different topographic models and a two-dimensional hydrodynamic model to simulate and compare the inundation dynamics associated with a levee failure scenario along embankment system of the river Montone, which flows eastward in the southern portion of the study area. For each topographic model, we quantified the flood hazard in terms of maximum water depth (h) and we compared the actual effects on flood-hazard dynamics of differential land-subsidence relative to those associated with other man-made topographic alterations, which resulted to be much more significant.

  19. Unmasking Sinkings Zones Caused by Subsidence-Creep Processes in Morelia, MICHOACÁN, Using Insar and GIS

    Science.gov (United States)

    Alejandro, Avila-Olivera Jorge; Paolo, Farina; Hugo, Garduño-Monroy Victor

    2008-05-01

    In Morelia City since the beginning of the 1980s, problems of differential sinkings, crackings and superficial faults affecting natural and anthropogenic structures have been observed. At the present time the city is being affected by nine faults, eight of which are related to Subsidence-Creep-Fault Processes (SCFP) and display a preferential direction ENE-WSW, identical to the Tula-Chapala regional faulting system. As part of the SCFP studies, GDPS and InSAR monitoring have been carried out; both showed that the maximum sinkings (3. 5 cm/year, summer 2003-summer 2007) are located in the NW part of the city, considered stable (in the past) due to the coverage of Pleistocene-Holocene basaltic-andesitic materials of Quinceo volcano. In order to resolve the enigma, all the available information related to the SCFP in the city have been integrated in a GIS; as well as two analysis of lithology columns were carried out to obtain a surface of the spatial distribution of the thickness of compressible materials in the city. The first analysis just increased the doubts, but the second one showed that the subsoil in the NW portion of Morelia consists of an interleave between basaltic-andesitic products of Quinceo volcano and lacustrine and/or fluviolacustrine sediments able to suffer deformations induced by groundwater withdrawal, which have been masked by the superficial volcanic products, that in addition are responsible of accelerating the process of land subsidence (sinkings) in function of weight these represent.

  20. Multi-temporal SAR data analysis for landcover, water-level changes, and subsidence studies in Southeastern Louisiana

    Science.gov (United States)

    Kwoun, O.; Lu, Z.

    2006-12-01

    We used multi-temporal European Remote Sensing Satellites 1 and 2 (ERS-1/2), Environment Satellite (ENVISAT), and Canadian RADARSAT-1 Synthetic Aperture Radar (SAR) images for ecological, hydrological, and geological studies of the Southeastern Louisiana coastal flood zone. First, we present a distinctive correlation among the seasonal changes in SAR backscatter, interferometric coherence, and land cover types with the associated normalized difference vegetation indices. Second, we demonstrate the use of C-band SAR images to measure changes in the water-level beneath moderately dense swamp forests, at a vertical accuracy and spatial resolution that is not possible with the current gauge-based measurements. Finally, we apply the conventional SAR interferometry (InSAR) and the Permanent Scatterer InSAR techniques to map land surface subsidence in New Orleans and the surrounding area; the comparison of measured subsidence patterns shows certain discrepancies that are probably due to atmospheric delays in this humid area. Our study demonstrates the importance of SAR data for understanding this coastal flood zone and the associated ecological, hydrological, and geological processes.

  1. Large networks of artificial radar reflectors to monitor land subsidence in natural lowlying coastal areas

    Science.gov (United States)

    Tosi, Luigi; Strozzi, Tazio; Teatini, Pietro

    2014-05-01

    Deltas, lagoons, estuaries are generally much prone to land subsidence. They are also very sensitive to land lowering due to their small elevation with respect to the mean sea level, also in view of the expected eustatic sea rise due to climate changes. Land subsidence can be presently monitored with an impressive accuracy by Persistent Scatterer Interferometry (PSI) on the large megacities that are often located on lowlying coastlands, e.g., Shanghai (China) on the Yangtze River delta, Dhaka (Bangladesh) on the Gange River delta, New Orleans (Louisiana) on the Mississippi river delta. Conversely, the land movements of the portions of these transitional coastlands where natural environments still persist are very challenging to be measured. The lack of anthropogenic structures strongly limits the use of PSI and the difficult accessibility caused by the presence of marshlands, tidal marshes, channels, and ponds yield traditional methodologies, such as levelling and GPS, both time-consuming and costly. In this contribution we present a unique experimental study aimed at using a large network of artificial radar reflectors to measure land subsidence in natural coastal areas. The test site is the 60-km long, 10-15 km wide lagoon of Venice, Italy, where previous PSI investigations revealed the lack of radar reflectors in large portions of the northern and southern lagoon basins (e.g., Teatini et al., 2011). A network of 57 trihedral corner reflectors (TCRs) were established between the end of 2006 and the beginning of 2007 and monitored by ENVISAT ASAR and TerraSAR-X acquisitions covering the time period from 2007 to 2011 (Strozzi et al., 2012). The application has provided general important insights on the possibility of controlling land subsidence using this approach. For example: (i) relatively small-size (from 0.5 to 1.0 m edge length) and cheap (few hundred euros) TCRs suffice to be clearly detectable from the radar sensors because of the low backscattering

  2. Preliminary results of land subsidence monitoring project in Konya Closed Basin between 2006–2009 by means of GNSS observations

    Directory of Open Access Journals (Sweden)

    A. Ustun

    2010-06-01

    Full Text Available One of the potential dangers that might arise as a result of bringing excessive amounts of groundwater to the surface of the Earth is land subsidence. Such surface deformations – these velocities may vary from a few millimetres to a few metres per year – do the greatest damage to infrastructure facilities and buildings in residential units. Agricultural lands, in which excessive irrigation is performed, and densely populated cities are more likely to suffer from land subsidence. Konya Closed Basin (KCB, where a rapid groundwater withdrawal has been observed during the last 30–40 years, is faced with such a threat. In this study, the possibility of the occurrence of land subsidence, related to groundwater withdrawal for the KCB, is assessed and the geodetic studies conducted up to now, with the intention of identifying land subsidence, are introduced. The vertical displacements of between -12 and -52 mm/year have been detected through GNSS observations collected on the 6-point test network. The land subsidence phenomenon has been developing in the areas where the groundwater is extensively used for irrigation and daily life. The results support the findings derived from the historical leveling records and point out the need of an extended study based on both GNSS and InSAR techniques for spatial and temporal mapping of land subsidence in the KCB.

  3. Preliminary results of land subsidence monitoring project in Konya Closed Basin between 2006-2009 by means of GNSS observations

    Science.gov (United States)

    Ustun, A.; Tusat, E.; Yalvac, S.

    2010-06-01

    One of the potential dangers that might arise as a result of bringing excessive amounts of groundwater to the surface of the Earth is land subsidence. Such surface deformations - these velocities may vary from a few millimetres to a few metres per year - do the greatest damage to infrastructure facilities and buildings in residential units. Agricultural lands, in which excessive irrigation is performed, and densely populated cities are more likely to suffer from land subsidence. Konya Closed Basin (KCB), where a rapid groundwater withdrawal has been observed during the last 30-40 years, is faced with such a threat. In this study, the possibility of the occurrence of land subsidence, related to groundwater withdrawal for the KCB, is assessed and the geodetic studies conducted up to now, with the intention of identifying land subsidence, are introduced. The vertical displacements of between -12 and -52 mm/year have been detected through GNSS observations collected on the 6-point test network. The land subsidence phenomenon has been developing in the areas where the groundwater is extensively used for irrigation and daily life. The results support the findings derived from the historical leveling records and point out the need of an extended study based on both GNSS and InSAR techniques for spatial and temporal mapping of land subsidence in the KCB.

  4. Groundwater-Mining-Induced Subsidence and Earth Fissures in Cedar Valley, Southwestern Utah

    Science.gov (United States)

    Knudsen, T. R.; Inkenbrandt, P.; Lund, W. R.; Lowe, M.; Bowman, S. D.

    2014-12-01

    Groundwater pumping in excess of recharge (groundwater mining) has lowered the potentiometric surface in Cedar Valley, southwestern Utah, by as much as 114 feet since 1939. Lowering the potentiometric surface (head decline) has caused permanent compaction of fine-grained sediments of the Cedar Valley aquifer. Recently acquired interferometric synthetic aperture radar (InSAR) imagery shows that land subsidence is occurring over an ~100 square-mile area, including two pronounced subsidence bowls in the northeastern (Enoch graben) and southwestern (Quichapa Lake area) parts of the valley. A lack of accurate historical benchmark elevation data over much of the valley prevents detailed long-term quantification of subsidence. In response to the land subsidence, earth fissures have formed along the margins of the Enoch graben and north and west of Quichapa Lake. Our initial inventory of Cedar Valley fissures, which relied on aerial-photography analysis, identified 3.9 miles of fissures in 2009. With newly acquired light detection and ranging (LiDAR) coverage in 2011, we more than doubled the total length of mapped fissures to 8.3 miles. Fissures on the west side of the Enoch graben exhibit ongoing vertical surface displacement with rates as high as 1.7 inches/year. The largest Enoch-graben-west fissure has displaced street surfaces, curb and gutter, and sidewalks, and has reversed the flow direction of a sewer line in a partially developed subdivision. Several Cedar Valley fissures are closely associated with, and in some places coincident with, mapped Quaternary faults. While the majority of Cedar Valley fissures are mapped in agricultural areas, continued groundwater mining and resultant subsidence will likely cause existing fissures to lengthen and new fissures to form that may eventually impact other developed areas of the valley.

  5. Using high resolution data to reveal depth-dependent mechanisms that drive land subsidence: The Venice coast, Italy

    Science.gov (United States)

    Tosi, L.; Teatini, P.; Carbognin, L.; Brancolini, G.

    2009-09-01

    Recent research has provided a high-resolution map that depicts the effect of land subsidence on the Venice coastal plain of Italy. The map, which covers the decade of 1992 to 2002, was obtained by an innovative "Subsidence Integrated Monitoring System" (SIMS), which efficiently merges the different displacement measurements obtained by high precision-leveling, differential and continuous Global Positing System data (GPS), and Synthetic Aperture Radar (SAR)-based interferometry. The displacement rates exhibit significant spatial variability, ranging from a slight 1 to 2 mm/yr uplift, to a serious subsidence of more than 10 mm/yr. This paper aims to describe the many natural and anthropogenic mechanisms that drive the pattern of the ground displacement. The movement sources are presented based on their depth of occurrence. Deep causes act at depths generally greater than 400 m below m.s.l. (mean sea level), and are recognizable in the movement of the pre-Quaternary basement. Medium causes act at depths between 400 and 50 m below m.s.l., and include geological features, such as a major presence of compressible clay layers in the southern and northern portions of the study area and groundwater withdrawals, mainly in the north-eastern coastland and western mainland. Shallow causes, i.e. those occurring from a depth of 50 m up to the ground surface, are related to the architecture and geomechanical properties of the Pleistocene and Holocene deposits, which are more thick and compressible approaching the littoral belt; geochemical compaction, due to the increasing salt concentration in the clayey sediments; and oxidation of the outcropping organic soils drained by land reclamation. These two latter factors primarily involve the southern portion of the Venice coast. The building loads in newly developed areas also cause local compaction of shallow deposits. We conclude that the consolidation of Holocene deposits and anthropogenic activities (groundwater withdrawal, land

  6. Late Carboniferous tectonic subsidence in South Wales: implications for Variscan basin evolution and tectonic history in SW Britain

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, P.M.; Gayer, R.A. [University of Cardiff, Cardiff (United Kingdom). Dept. of Earth Sciences

    2000-01-01

    Detailed stratigraphic data were used to backstrip seven sections from the Carboniferous South Wales coal basin. Resulting tectonic subsidence curves for the interval 319-305 Ma (Namurian-Westphalian D) are convex-up, indicating increasing subsidence rate with time, with rates between 130 and 250 m Ma{sup -1} suggesting a foreland basin setting. Forward modelling of subsidence due to flexural loading in front of a propagating orogenic wedge shows that an orogenic load migrating in a north-northeasterly direction across SW England between 319 and 305 Ma could have generated the backstripped subsidence patterns. Sensitivity tests show that while many of the forward model parameters are poorly constrained, and the model results non-unique, backstripped subsidence patterns allow reasonable constraint on the different model cases, so that model predictions can be treated as one possibility in a limited range. The predicted load evolution is consistent with current knowledge of tectonic and stratigraphic features of SW England. These results suggest that subsidence in other Late Carboniferous UK basins may also have been influenced by flexure due to a propagating orogenic load.

  7. A simple model for the assessment of indoor radionuclide Pb-210 surface contamination due to the presence of radon

    Directory of Open Access Journals (Sweden)

    Mrđa Dušan S.

    2013-01-01

    Full Text Available The presented, very simplified model provides a possibility for estimation of surface Pb-210 activity, depending on the changes of Rn-222 concentration during the long-term radon presence inside the closed room. This can be useful for retrospective assessment of the average indoor radon concentration for certain historical period, based on the surface contamination by the radionuclide Pb-210 in a closed or poorly ventilated room over a long period of time. However, the surface Pb-210 contamination depends on the pattern of radon concentration changes, and in this model is supposed that the change of indoor radon concentration, which periodically enters the room, is affected only by the radioactive decay and the inserted amount of radon in each entry. So, each radon entry can be comprehended as a “net amount” of radon, or excess which remains inside the room due to radon’s periodical in-out flow. It is shown, that under the conditions of the model, the achieved average value of radon concentration of 275 Bq/m3, implies that the saturated surface contamination by the Pb-210 of 160 Bq/m2 after approximately 150 years. [Projekat Ministarstva nauke Republike Srbije, br. 171002: Nuclear Methods Investigations of Rare Processes and Cosmic Rays i br. 43002: Biosensing Technologies and Global System for Continuous Research and Integrated Management of ecosystems

  8. Large enhancement of nonlinear Goos-Hänchen shifts and optical bistability due to surface plasmon excitations

    Science.gov (United States)

    Kim, Kihong

    2015-12-01

    The Goos-Hänchen shift of p wave beams incident on a metal-nonlinear dielectric bilayer in the Kretschmann configuration is studied theoretically. The reflectance, the phase of the reflection coefficient and the Goos-Hänchen shift are calculated in a numerically precise manner by using the invariant imbedding method. The Goos-Hänchen shift has been found to be able to take both extremely large positive and negative values due to surface plasmon excitations and very strong bistability and unique hysteresis phenomena appear. In addition, several previous results on the intensity dependence of the Goos-Hänchen shift are pointed out to be erroneous.

  9. Subsidence and associated shallow faulting hazard assessment in central Mexico using InSAR and GPS

    Science.gov (United States)

    Cabral-Cano, E.; Solano Rojas, D. E.; Oliver-Cabrera, T.; Salazar-Tlaczani, L.; Wdowinski, S.; DeMets, C.; Pacheco, J.

    2014-12-01

    While subsidence has affected Mexico City for over a century, other cities in central Mexico have been subjected to subsidence since the '80, as a result of their large urban expansion, population increase and aggressive groundwater extraction rates. The continuous subsidence results in severe damage to urban infrastructure and civil structures. Unfortunately the damage cost assessment and vulnerability are difficult to evaluate, because of the variable geographic extent and the continuous nature of the process, which have different characteristics than localized, short duration hazards, as earthquakes or flood events.We have monitored land subsidence in 17 cities in central Mexico using both InSAR and GPS observations. InSAR provides an unsurpassed synoptic view of the earth's dynamic surface. However, different satellite sensors and sometimes widely spaced data availability make it difficult to derive long-term time series, rapid changes or nonlinear variations of subsidence velocities. To alleviate this situation, higher temporal resolution subsidence observations of associated fault motion has been pursued using continuously operating GPS stations. We have developed a GPS network that covers 6 urban centers to detect short duration variations using different processing schemes that include both real-time solutions using RTNet as well as daily solution using Gipsy-Oasis.Cartographic products based on these techniques have been merged with other population, hydrology and meteorology data sets. This approach allows a better hazard assessment and provides information for other purposes, such as vulnerability for shallow faulting, land use zonations, and other decision elements for water resource management agencies. We will provide examples of these hazard assessments for several cities, including Mexico City, Aguascalientes, Morelia, Irapuato and Celaya and the challenges encountered to integrate these results with other data sets from federal and state

  10. Differences in coastal subsidence in southern Oregon (USA) during at least six prehistoric megathrust earthquakes

    Science.gov (United States)

    Milker, Yvonne; Nelson, Alan R.; Horton, Benjamin P.; Engelhart, Simon E.; Bradley, Lee-Ann; Witter, Robert C.

    2016-06-01

    Stratigraphic, sedimentologic (including CT 3D X-ray tomography scans), foraminiferal, and radiocarbon analyses show that at least six of seven abrupt peat-to-mud contacts in cores from a tidal marsh at Talbot Creek (South Slough, Coos Bay), record sudden subsidence (relative sea-level rise) during great megathrust earthquakes at the Cascadia subduction zone. Data for one contact are insufficient to infer whether or not it records a great earthquake-it may also have formed through local, non-seismic, hydrographic processes. To estimate the amount of subsidence marked by each contact, we expanded a previous regional modern foraminiferal dataset to 174 samples from six Oregon estuaries. Using a transfer function derived from the new dataset, estimates of coseismic subsidence across the six earthquake contacts vary from 0.31 m to 0.75 m. Comparison of subsidence estimates for three contacts in adjacent cores shows within-site differences of ≤0.10 m, about half the ±0.22 m error, although some estimates may be minimums due to uncertain ecological preferences for Balticammina pseudomacrescens in brackish environments and almost monospecific assemblages of Miliammina fusca on tidal flats. We also account for the influence of taphonomic processes, such as infiltration of mud with mixed foraminiferal assemblages into peat, on subsidence estimates. Comparisons of our subsidence estimates with values for correlative contacts at other Oregon sites suggest that some of our estimates are minimums and that Cascadia's megathrust earthquake ruptures have been heterogeneous over the past 3500 years.

  11. Model tests on interaction between soil and geosynthetics subjected to localized subsidence in landfills

    Institute of Scientific and Technical Information of China (English)

    Bin ZHU; Deng GAO; Jun-chao LI; Yun-min CHEN

    2012-01-01

    In a landfill,excessive tensile strains or failure of the liner system due to localized subsidence underneath the geosynthetic liner,is a concern in design and operation of the landfill.The localized subsidence can be commonly withstood by reinforcements such as geogrids.A total of nine model tests were carried out to study the influence of soil arching in overburden sandy soil on the geosynthetics and the interaction between the soil and the geosynthetics.The localized subsidence was modeled by a strip trapdoor under the geosynthetic reinforcements.The reinforcement includes several layers of polyvinylchlorid (PVC) membrane or both PVC membrane and a compacted clay layer.Test results show that the vertical soil pressure acting on the geosynthetics within the subsidence zone is strongly related to the deflection of the geosynthetics.The soil pressure acting on the deflected geosynthetics will decrease to a minimum value with respect to its deflection if the final deflection is large enough,and this minimum value is almost independent of the overburden height.Otherwise,the deflection of geosynthetics cannot result in a full degree of soil arching,and the soil pressure within the subsidence zone increases with the increase of overburden height.Deflections and strains of the geosynthetics obviously decrease with the increase of their tensile stiffness.The presence of a compacted clay layer buffer can therefore reduce both deflections and strains of the geosynthetics.Finally,a composite liner structure is recommended for landfills to withstand the localized subsidences.

  12. Subsidence and Stress Change in the Cerro Prieto Geothermal Field, B. C., Mexico

    Science.gov (United States)

    Glowacka, E.; Sarychikhina, O.; Nava, F. A.

    2005-11-01

    Previous works have shown that ground deformation and seismicity in the Cerro Prieto geothermal field (CPGF) are due to both tectonics and field exploitation. Here, we use information about current tectonics and data from precision leveling surveys, to model tectonic and anthropogenic subsidence. Our results show that tectonic subsidence constitutes only ˜4% of the measured subsidence. Anthropogenic subsidence was evaluated using a model of rectangular tensional cracks, based on the hydrological model of the field, together with the Coulomb 2.0 program. From the resulting values of the fissure parameters and from extraction and injection data, we calculate that the volume changes caused by closure of the geothermal and cold water reservoirs account for only ˜3% and ˜7%, respectively, of the volume change which should occur due to extraction. Since 18% of the extracted fluids are reinjected, external recharge must compensate for about 72% of the expected volume reduction. An analysis of the changes in Coulomb stress caused by exploitation of the geothermal field suggest that even though the anthropogenic stresses account for only a fraction of tectonic stresses, they are large enough to trigger seismicity.

  13. Evolution of long-term land subsidence near Mexico City: Review, field investigations, and predictive simulations

    Science.gov (United States)

    Ortiz-Zamora, Dalia; Ortega-Guerrero, Adrian

    2010-01-01

    Aquitard consolidation in the Chalco Plain is the most recent of a series of major land subsidence problems near Mexico City caused by leaky-aquifer pumping and involving a complex distribution of basalt flows within a lacustrine sequence. This study first conducted a ground magnetic survey combined with lithologic logs to map the extension of basalts. Then it assessed the evolution of ground surface elevations and updated hydraulic heads in the aquifer and aquitard in order to verify the accuracy of previous simulations and develop new predictions on land subsidence employing a one-dimensional, nonlinear, groundwater flow-consolidation model. Results show the presence of shallow basalts that extend from Sierra Santa Catarina into the Chalco Plain, causing a differential consolidation that controls both the distribution of large-scale fractures in the aquitard and the shape of a new lake. Cumulative land subsidence in the center of the Chalco Plain reached 13 m in 2006, thus closely matching previous numerical estimations. Since 1985, the ground surface decline has continued at a rate of ˜0.40 m/yr, while the potentiometric surface decline in the aquifer proceeds at an average rate of ˜1.5 m/yr, indicating that the flow system has not yet reached steady-state conditions. Numerical predictions show that under current pumping rates, where the aquitard is 300 m, total land subsidence will reach ˜19 m by the year 2020; while where the aquitard is 140 m thick, total land subsidence will reach ˜12 m, and increase the risk of flooding and aquitard fracturing for nearby urban centers.

  14. Feedback of land subsidence on the movement and conjunctive use of water resources

    Science.gov (United States)

    Hanson, R. T.; Schmid, W.; Hughes, J. D.

    2014-12-01

    The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent flows that also depend on aquifer head and other flow terms. In a test example, flows most affected were stream seepage and evapotranspiration from groundwater (ETgw). Deformation feedback also had an indirect effect on conjunctive surface- and groundwater use components: Changed stream seepage and streamflows influenced surface-water deliveries and returnflows. Changed ETgw impacted on irrigation demand, which jointly with altered surface-water supplies resulted in changed supplemental groundwater requirements and pumping and changed return runoff. This modeling feature will improve the impact assessment of dewatering-induced land subsidence/uplift (following irrigation pumping or coal-seam gas extraction) on surface receptors, inter-basin transfers, and surface-infrastructure integrity. A hypothetical example and the Central Valley are used to demonstrate the utility and importance of the new subsidence model linkages for conjunctive use.

  15. Polymer bilayer formation due to specific interactions between beta-cyclodextrin and adamantane: a surface force study.

    Science.gov (United States)

    Blomberg, Eva; Kumpulainen, Atte; David, Christelle; Amiel, Catherine

    2004-11-23

    The purposes of this study are to utilize the interactions between an adamantane end-capped poly(ethylene oxide) (PEO) and a cationic polymer of beta-cyclodextrin to build polymer bilayers on negatively charged surfaces, and to investigate the interactions between such layers. The association of this system in solution has been studied by rheology, light scattering, and fluorescence measurements. It was found that the adamantane-terminated PEO (PEO-Ad) mixed with the beta-cyclodextrin polymer gives complexes where the interpolymer links are formed by specific inclusion of the adamantane groups in the beta-cyclodextrin cavities. This results in a higher viscosity of the solution and growth of intermolecular clusters. The interactions between surfaces coated with a cationized beta-cyclodextrin polymer across a water solution containing PEO-Ad polymers were studied by employing the interferometric surface force apparatus (SFA). In the first step, the interaction between mica surfaces coated with the cationized beta-cyclodextrin polymer in pure water was investigated. It was found that the beta-cyclodextrin polymer adsorbs onto mica and almost neutralizes the surface charge. The adsorbed layers of the beta-cyclodextrin polymer are rather compact, with a layer thickness of about 60 A (30 A per surface). Upon separation, a very weak attractive force is observed. The beta-cyclodextrin solution was then diluted by pure water by a factor of 3000 and a PEO-Ad polymer was introduced into the solution. Two different architectures of the PEO-Ad polymer were investigated: a four-arm structure and a linear structure. After the adsorption of the PEO polymer onto the beta-cyclodextrin layer reached equilibrium, the forces were measured again. It was found that the weak repulsive long-range force had disappeared and an attractive force caused the surfaces to jump into contact, and that the compressed layer thickness had increased. The attractive force is interpreted as being due to

  16. An Updated Estimation of Radiative Forcing due to CO2 and Its Effect on Global Surface Temperature Change

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; ZHANG Ruoyu; SHI Guangyu

    2013-01-01

    New estimations of radiative forcing due to CO2 were calculated using updated concentration data of CO2 and a high-resolution radiative transfer model.The stratospheric adjusted radiative forcing (ARF)due to CO2 from the year 1750 to the updated year of 2010 was found to have increased to 1.95 W m-2,which was 17% larger than that of the IPCC's 4th Assessment Report because of the rapid increase in CO2 concentrations since 2005.A new formula is proposed to accurately describe the relationship between the ARF of CO2 and its concentration.Furthermore,according to the relationship between the ARF and surface temperature change,possible changes in equilibrium surface temperature were estimated under the scenarios that the concentration of CO2 increases to 1.5,2,2.5,3,3.5 and 4 times that of the concentration in the year 2008.The result was values of +2.2℃,+3.8℃,+5.1℃,+6.2℃,+7.1℃ and +8.0℃ respectively,based on a middle-level climate sensitivity parameter of 0.8 K (W m-2)-1.Non-equilibrium surface temperature changes over the next 500 years were also calculated under two kinds of emission scenarios (pulsed and sustained emissions) as a comparison,according to the Absolute Global Temperature change Potential (AGTP) of CO2.Results showed that CO2 will likely continue to contribute to global warming if no emission controls are imposed,and the effect on the Earth-atmosphere system will be difficult to restore to its original level.

  17. Alteration of the carbon and nitrogen isotopic composition in the Martian surface rocks due to cosmic ray exposure

    Science.gov (United States)

    Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.

    2014-06-01

    13C/12C and 15N/14N isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce 13C and 15N isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both 13C and 15N due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is Mars can explain its high-temperature heavy nitrogen isotopic composition (15N/14N). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

  18. Alteration of the Carbon and Nitrogen Isotopic Composition in the Martian Surface Rocks Due to Cosmic Ray Exposure

    Science.gov (United States)

    Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.

    2014-01-01

    C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

  19. Temperature rise in objects due to optical focused beam through atmospheric turbulence near ground and ocean surface

    Science.gov (United States)

    Stoneback, Matthew; Ishimaru, Akira; Reinhardt, Colin; Kuga, Yasuo

    2013-03-01

    We consider an optical beam propagated through the atmosphere and incident on an object causing a temperature rise. In clear air, the physical characteristics of the optical beam transmitted to the object surface are influenced primarily by the effect of atmospheric turbulence, which can be significant near the ground or ocean surface. We use a statistical model to quantify the expected power transfer through turbulent atmosphere and provide guidance toward the threshold of thermal blooming for the considered scenarios. The bulk thermal characteristics of the materials considered are used in a thermal diffusion model to determine the net temperature rise at the object surface due to the incident optical beam. These results of the study are presented in graphical form and are of particular interest to operators of high power laser systems operating over large distances through the atmosphere. Numerical examples include a CO2 laser (λ=10.6 μm) with: aperture size of 5 cm, varied pulse duration, and propagation distance of 0.5 km incident on 0.1-mm copper, 10-mm polyimide, 1-mm water, and 10-mm glass/resin composite targets. To assess the effect of near ground/ocean laser propagation, we compare turbulent (of varying degrees) and nonturbulent atmosphere.

  20. Integration of MODIS data and Short Baseline Subset (SBAS) technique for land subsidence monitoring in Datong, China

    Science.gov (United States)

    Zhao, Chao-ying; Zhang, Qin; Yang, Chengsheng; Zou, Weibao

    2011-07-01

    Datong is located in the north of Shanxi Province, which is famous for its old-fashioned coal-mining preservation in China. Some serious issues such as land subsidence, ground fissures, mining collapse, and earthquake hazards have occurred over this area for a long time resulting in significant damages to buildings and roads. In order to monitor and mitigate these natural man-made hazards, Short Baseline Subsets (SBAS) InSAR technique with ten Envisat ASAR data is applied to detect the surface deformation over an area of thousands of square kilometers. Then, five MODIS data are used to check the atmospheric effects on InSAR interferograms. Finally, nine nonlinear land subsidence cumulative results during September 2004 and February 2008 are obtained. Based on the deformation data, three kinds of land subsidence are clearly detected, caused by mine extraction, underground water withdrawal and construction of new economic zones, respectively. The annual mean velocity of subsidence can reach 1 to 4 cm/year in different subsidence areas. A newly designed high-speed railway (HSR) with speeds of 350 km/h will cross through the Datong hi-tech zone. Special measures should be taken for the long run of this project. In addition, another two subsidence regions need further investigation to mitigate such hazards.

  1. Integration of MODIS data and short baseline subset (SBAS) technique for land subsidence monitoring in Datong, China

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, C.Y.; Zhang, Q.; Yang, C.S.; Zou, W.B. [Changan University, Xian (China)

    2011-07-15

    Datong is located in the north of Shanxi Province, which is famous for its old-fashioned coal-mining preservation in China. Some serious issues such as land subsidence, ground fissures, mining collapse, and earthquake hazards have occurred over this area for a long time resulting in significant damages to buildings and roads. In order to monitor and mitigate these natural man-made hazards, Short Baseline Subsets (SBAS) InSAR technique with ten Envisat ASAR data is applied to detect the surface deformation over an area of thousands of square kilometers. Then, five MODIS data are used to check the atmospheric effects on InSAR interferograms. Finally, nine nonlinear land subsidence cumulative results during September 2004 and February 2008 are obtained. Based on the deformation data, three kinds of land subsidence are clearly detected, caused by mine extraction, underground water withdrawal and construction of new economic zones, respectively. The annual mean velocity of subsidence can reach 1 to 4 cm/year in different subsidence areas. A newly designed high-speed railway (HSR) with speeds of 350 km/h will cross through the Datong hi-tech zone. Special measures should be taken for the long run of this project. In addition, another two subsidence regions need further investigation to mitigate such hazards.

  2. Effects of groundwater regulation on aquifer-system compaction and subsidence in the Houston-Galveston Region, Texas, USA

    Science.gov (United States)

    Turco, M. J.; Petrov, A.

    2015-11-01

    Subsidence has been a primary concern in the Houston area for many years. Since 1906, about 4 m of subsidence has occurred in the coastal areas, with a broad area of about 2 m of subsidence existing today throughout most of the Houston Area. In 1975, as a result of area residents and local governments becoming increasingly alarmed by the continued impact of subsidence on economic growth and quality of life in the region, the Harris-Galveston Subsidence District was created by the 64th Texas Legislature as an underground water conservation district with the mission to provide for the regulation of the withdrawal of groundwater to control subsidence. Over its nearly 40 years of existence, the District has developed substantial data sets providing the foundation for its regulatory plan. The District's regulatory plan allows groundwater users an amount of annual groundwater based on a percentage of an individual permitee's total water demand. The management of the groundwater resources within the District has involved significant coordination with regional ground and surface water suppliers; ongoing interaction with other state and local regulatory bodies; analysis of accurate and up to date predictions on water usage; the enforcement of disincentives to those who rely too heavily on groundwater and a commitment to practicing and promoting water conservation. Areas nearest the Gulf of Mexico coast have completed the conversion to alternative (other than groundwater) water sources, consequently the effective stress on the aquifer has decreased and subsidence rates have been reduced. Areas within the District further inland are currently proceeding through the conversion process, and subsidence has continued in those areas as development of the groundwater resources has continued.

  3. Differential substrate subsidence of the EnviHUT project pitched extensive green roof

    Directory of Open Access Journals (Sweden)

    Nečadová Klára

    2017-01-01

    Full Text Available In primary phase of testing building physical characteristics of the EnviHUT project extensive and semi-intensive roofs with 30° inclination occurred exceptional substrate subsidence. An extensive testing field with retaining geocell-system evinced differential subsidence of individual sectors after six months. Measured subsidence of installed substrate reached 40 % subsidence compared to originally designed height (intended layer thickness. Subsequent deformation of geocell-system additionally caused partial slide of substrate to drip edge area. These slides also influenced initial development of stonecrop plants on its surface. Except functional shortages the aesthetical function of the whole construction is influenced by the mentioned problem. The stated paper solves mentioned issues in view of installation method optimization, selection and modification of used roof substrate and in view of modification of geometric and building installed elements retaining system arrangement. Careful adjustment of roof system geometry and enrichment of original substrate fraction allow full functionality from pitched extensive green roof setting up. The modification scheme and its substantiation is a part of this technical study output.

  4. Is There a Tectonic Component On The Subsidence Process In Morelia, Mexico?

    Science.gov (United States)

    Cabral-Cano, E.; Arciniega-Ceballos, A.; Diaz-Molina, O.; Garduno-Monroy, V.; Avila-Olivera, J.; Hernández-Madrigal, V.; Hernández-Quintero, E.

    2009-12-01

    Subsidence and faulting have affected cities in central Mexico for decades. This process causes substantial damages to the urban infrastructure, housing and large buildings, and is an important factor to be consider when planning urban development, land use zoning and hazard mitigation strategies. In Mexico, studies using InSAR and GPS based observations have shown that high subsidence areas are usually associated with the presence of thick lacustrine and fluvial deposits. In most cases the subsidence is closely associated with intense groundwater extraction that results in sediment consolidation. However, recent studies in the colonial city of Morelia in central Mexico show a different scenario, where groundwater extraction cannot solely explain the observed surface deformation. Our results indicate that a more complex interplay between sediment consolidation and tectonic forces is responsible for the subsidence and fault distribution within the city. The city of Morelia has experienced fault development recognized since the 80’s. This situation has led to the recognition of 9 NE-SW trending faults that cover most of its urbanized area. Displacement maps derived from differential InSAR analysis show that the La Colina fault is the highest subsiding area in Morelia with maximum annual rates over -35 mm/yr. However, lithological mapping and field reconnaissance clearly show basalts outcropping this area of high surface deformation. The subsurface characterization of the La Colina fault was carried out along 27 Ground Penetrating Radar (GPR) sections and 6 seismic tomography profiles. Assuming a constant, linear past behavior of the subsidence as observed by InSAR techniques, and based on the interpretation of the fault dislocation imaged by the shallow GPR and seismic tomography, it is suggested that the La Colina fault may have been active for the past 220-340 years and clearly pre-dates the intense water well extraction from the past century. These conditions

  5. Dependence of implantation sequence on surface blistering characteristics due to H and He ions co-implanted in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liang, J.H. [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Hsieh, H.Y.; Wu, C.W. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Lin, C.M. [Department of Applied Science, National Hsinchu University of Education, Hsinchu 300, Taiwan, ROC (China)

    2015-12-15

    This study investigated surface blistering characteristics due to H and He ions co-implanted in silicon at room temperature. The H and He ion energies were 40 and 50 keV, respectively, so that their depth profiles were similar. The total implantation fluence for the H and He ions was 5 × 10{sup 16} cm{sup −2} under various fluence fractions in the H ions. The implantation sequences under investigation were He + H and H + He. Dynamic optical microscopy (DOM) was employed in order to dynamically analyze surface blistering characteristics. This study used DOM data to construct so-called time–temperature–transformation (T–T–T) curves to easily predict blistering and crater transformation at specific annealing times and temperatures. The results revealed that the curves of blister initialization, crater initialization, and crater completion in the He + H implant occurred at a lower annealing temperature but with a longer annealing time compared to those in the H + He implant. Furthermore, the threshold annealing temperatures for blister and crater formation in the He + H implant were lower than they were in the H + He implant. The size distributions of the blisters and craters in the He + H implant extended wider than those in the H + He implant. In addition, the He + H implant exhibited larger blisters and craters compared to the ones in the H + He implant. Since the former has a higher percentage of exfoliation area than the latter, it is regarded as the more optimal implantation sequence.

  6. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  7. Global crop yield reductions due to surface ozone exposure: 1. Year 2000 crop production losses and economic damage

    Science.gov (United States)

    Avnery, Shiri; Mauzerall, Denise L.; Liu, Junfeng; Horowitz, Larry W.

    2011-04-01

    Exposure to elevated concentrations of surface ozone (O 3) causes substantial reductions in the agricultural yields of many crops. As emissions of O 3 precursors rise in many parts of the world over the next few decades, yield reductions from O 3 exposure appear likely to increase the challenges of feeding a global population projected to grow from 6 to 9 billion between 2000 and 2050. This study estimates year 2000 global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure using hourly O 3 concentrations simulated by the Model for Ozone and Related Chemical Tracers version 2.4 (MOZART-2). We calculate crop losses according to two metrics of ozone exposure - seasonal daytime (08:00-19:59) mean O 3 (M12) and accumulated O 3 above a threshold of 40 ppbv (AOT40) - and predict crop yield losses using crop-specific O 3 concentration:response functions established by field studies. Our results indicate that year 2000 O 3-induced global yield reductions ranged, depending on the metric used, from 8.5-14% for soybean, 3.9-15% for wheat, and 2.2-5.5% for maize. Global crop production losses totaled 79-121 million metric tons, worth $11-18 billion annually (USD 2000). Our calculated yield reductions agree well with previous estimates, providing further evidence that yields of major crops across the globe are already being substantially reduced by exposure to surface ozone - a risk that will grow unless O 3-precursor emissions are curbed in the future or crop cultivars are developed and utilized that are resistant to O 3.

  8. MODELING THE ANOMALY OF SURFACE NUMBER DENSITIES OF GALAXIES ON THE GALACTIC EXTINCTION MAP DUE TO THEIR FIR EMISSION CONTAMINATION

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, Toshiya; Suto, Yasushi; Taruya, Atsushi; Yahata, Kazuhiro [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Kayo, Issha [Department of Physics, Toho University, Funabashi, Chiba 274-8510 (Japan); Nishimichi, Takahiro, E-mail: kashiwagi@utap.phys.s.u-tokyo.ac.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan)

    2015-02-01

    The most widely used Galactic extinction map is constructed assuming that the observed far-infrared (FIR) fluxes come entirely from Galactic dust. According to the earlier suggestion by Yahata et al., we consider how FIR emission of galaxies affects the SFD map. We first compute the surface number density of Sloan Digital Sky Survey (SDSS) DR7 galaxies as a function of the r-band extinction, A {sub r,} {sub SFD}. We confirm that the surface densities of those galaxies positively correlate with A {sub r,} {sub SFD} for A {sub r,} {sub SFD} < 0.1, as first discovered by Yahata et al. for SDSS DR4 galaxies. Next we construct an analytical model to compute the surface density of galaxies, taking into account the contamination of their FIR emission. We adopt a log-normal probability distribution for the ratio of 100 μm and r-band luminosities of each galaxy, y ≡ (νL){sub 100} {sub μm}/(νL) {sub r}. Then we search for the mean and rms values of y that fit the observed anomaly, using the analytical model. The required values to reproduce the anomaly are roughly consistent with those measured from the stacking analysis of SDSS galaxies. Due to the limitation of our statistical modeling, we are not yet able to remove the FIR contamination of galaxies from the extinction map. Nevertheless, the agreement with the model prediction suggests that the FIR emission of galaxies is mainly responsible for the observed anomaly. Whereas the corresponding systematic error in the Galactic extinction map is 0.1-1 mmag, it is directly correlated with galaxy clustering and thus needs to be carefully examined in precision cosmology.

  9. An Integrated Assessment Framework for land subsidence in Delta cities

    Science.gov (United States)

    Bucx, T.; van Ruiten, K.; Erkens, G.

    2013-12-01

    In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten. Without change, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other delta (and coastal) cities will sink below sea level. Increased flooding and also other wide¬spread impacts of land subsidence result already in damage of billions of dollars per year to roads, embankments, subsurface infrastructure and housing. Moreover the potential damage caused by increased flood risk is around the same amount of money. A major cause for severe land subsidence is excessive groundwater extraction related to rapid urbanization and population growth. A major rethink is needed to resolve the ';hidden' but urgent threat of subsidence in a multi-sectoral perspective. A comprehensive approach is presented to address land subsidence for more sustainable and resilient urban development. Land subsidence is an issue that involves many policy fields, complex technical aspects and governance. There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies and measures that are effective and efficient on both the short and long term. Urban (ground)water management, adaptive flood risk management and related spatial planning strategies should be taken into account. This presentation will introduce and illustrate an Integrated Assessment Framework (IAF) for land subsidence that has been developed in the European FP7 project Subcoast. This framework is based on an integrated (multi-sectoral) approach and can be used to gain insight in the complex aspects of subsidence, to raise awareness and to support decision making on appropriate adaptation strategies and measures. The IAF is addressing all aspects of subsidence: from primary causes, vulnerability, impacts and risks towards responses and solutions. It will also take into account the three spatial layers (Occupation, Network and Base layer), governance aspects and several scenarios (economic

  10. Coal mining GPS subsidence monitoring technology and its application

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Peng Xiangguo; Xu Chang hui

    2011-01-01

    We proved theoretically that geodetic height,measured with Global Positioning System (GPS),can be applied directly to monitor coal mine subsidence.Based on a Support Vector Machine (SVM) model,we built a regional geoid model with a Gaussian Radial Basis Function (RBF) and the technical scheme for GPS coal mine subsidence monitoring is presented to provide subsidence information for updating the regional Digital Elevation Model (DEM).The theory proposed was applied to monitor mining subsidence in an Inner Mongolia coal mine in China.The scheme established an accurate GPS reference network and a comprehensive leveling conjunction provided the normal height of all GPS control points.According to the case study,the SVM model to establish geoid-model is better than a polynomial fit or a Genetic Algorithm based Back Propagation (GA-BP) neural network.GPS-RTK measurements of coal mine subsidence information can be quickly acquired for updating the DEM.

  11. 中国高潜水位沉陷区采煤废弃物复垦农田的土壤特征%Soil properties in reclaimed farmland by filling subsidence basin due to underground coal mining with mineral wastes in China

    Institute of Scientific and Technical Information of China (English)

    程伟; 卞正富; 董霁红; 雷少刚

    2014-01-01

    为了研究充填介质对中国东部高潜水位采煤塌陷区复垦土壤特征的影响,对采用煤矸石或粉煤灰作为充填介质形成的复垦土壤化学和微生物指标进行分析。结果表明,充填介质粉煤灰的存在能显著提高复垦土壤中pH值和含水率;在0~10 cm、10~20 cm、20~50 cm土壤层,采用粉煤灰形成的复垦土壤 MBC、MBN、MBC/TOC的比率高于采用煤矸石形成的复垦土壤;采用煤矸石作为充填介质形成的复垦土壤中,重金属As和Cr含量、土壤微生物碳氮比、呼吸熵等高于对照土壤和粉煤灰充填形成的复垦土壤;主成分分析表明,充填土壤中重金属含量、土壤微生物量和土壤酶活性能代表大部分复垦土壤特征。%Reclaimed mining-induced subsidence area soils (RMSs) could restore soil quality and crop productivity in coal mining area. This study was conducted to evaluate the effects of mineral-processing wastes (fly ash vs coal gangue) as backfill substrates on soil chemical and microbial properties in mining-induced subsidence area. A general higher water holding capacity (WHC) and pH had been observed in fly ash than coal gangue reconstructed soil. Soil microbial biomass C (MBC) and N (MBN), MBC/TOC (total organic carbon) ratio (qmic) were higher under the influence of the fly ash, while contents of As, Cr, C/Nbio, the basal respiration per unit of microbial biomass (QCO2) were higher under the coal gangue reconstructed mode in 0-10, 10-20, 20-50 cm layers. The microbial basal respiration was higher in 0-10, 10-20, 0-50 cm layers, while was lower in 20-50 cm layer under fly ash than that of coal gangue reconstructed mode. The lower QCO2 of fly ash mine soil suggested the lower maintenance energy requirement of the microbial community. Moreover, the contents of metals may possibly have negative implications for soil microbial and enzyme activities in reconstructed soil.

  12. Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico)

    Science.gov (United States)

    Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.

    2013-12-01

    This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

  13. Physical experiments of land subsidence within a maar crater: insights for porosity variations and fracture localization

    Science.gov (United States)

    Cerca, M.; Rocha, L.; Carreón-Freyre, D.; Aranda, J.

    2015-11-01

    We present the results of a series of physical models aiming to reproduce rapid subsidence (at least 25 m in 30 years) observed in the sediments of a maar crater caused by extraction of groundwater in the interconnected adjacent aquifer. The model considered plausible variations in the geometry of the crater basement and the measured rate of groundwater extraction (1 m per year in the time interval from 2005 to 2011) in 15 wells located around the structure. The experiments were built within a rigid plastic bowl in which the sediments and rocks of the maar sequence were modeled using different materials: (a) plasticine for the rigid country rock, (b) gravel for the fractured country rock forming the diatreme fill and, (c) water saturated hollow glass microbeads for the lacustrine sedimentary fill of the crater. Water table was maintained initially at the surface of the sediments and then was allowed to flow through a hole made at the base of the rigid bowl. Water extraction provoked a sequence of gentle deformation, fracturing, and faulting of the surface in all the experiments. Vertical as well as lateral displacements were observed in the surface of the experiments. We discuss the results of 2 representative models. The model results reproduced the main geometry of the ring faults affecting the crater sediments and helps to explain the diversity of structures observed in relation with the diatreme geometry. The surface of the models was monitored continuously with an optical interferometric technique called structured light projection. Images collected at nearly constant time intervals were analyzed using the ZEBRA software and the obtained interferometric pairs permitted to analyze the full field subsidence in the model (submilimetric vertical displacements). The experiments were conducted at a continuous flow rate extraction and show a also a linear subsidence rate. Comparison among the results of the physical models and the fault system associated to

  14. Morphology, genesis and distribution of subsidence features in Dinaric karst in Slovenia

    Science.gov (United States)

    Mihevc, Andrej

    2016-04-01

    Dinaric karst is built mostly of Mesozoic limestones and dolomites. Because of large uninterrupted areas of karst, long geomorphic evolution and pure karst rocks there is not much sediment cover over karst. In spite of that the appearing of subsidence are very common. They are connected to parts of karst with specific geomorphic evolution, mostly contact karst and karst poljes where thick clastic sediments are deposited. Contact karst is the karst that developed under the impact of allogenic streams. As the contact of surface and underground flow is sensitive in some past climatic conditions these areas were often zones of sedimentation. At present washing of sediments into karst prevails sedimentation causing subsidence in ponor zones of blind valleys or border depressions very frequent. Karst poljes are the areas of karst where karst water table is close to the surface. This means low vertical gradient in karst and sedimentation or good sediment preservation. However, because of regular seasonal oscillations of water level, part of the year these sediments are in conditions where piping and subsidence can occur. In both areas collapses occur after the floods or after drop of the level of karst water below surface, mostly close to ponors or estavelles. On other geomorphic settings where collapses occur like relict poljes, dry valleys or on levelled surfaces they occur after heavy rains, often connected with thawing of snow. Collapse features are mostly cylindrical or steep-sided, usually a few metres to tens of metres in diameter. With time they transform to shallow depressions or funnel like dolines. From the point of view of geohazard the main zones of subsidence are well known and respected by locals. Even land use in endangered zones is usual less intensive and the damage caused by them is relatively small. However with loosing traditional knowledge, disobeying recommendations and growth of settlements and infrastructure the likelihood of damage increases.

  15. FINITE ELEMENT NUMERICAL SIMULATION OF LAND SUBSIDENCE AND GROUNDWATER EXPLOITATION BASED ON VISCO-ELASTIC PLASTIC BLOT'S CONSOLIDATION THEORY

    Institute of Scientific and Technical Information of China (English)

    LUO Zu-jiang; ZENG Feng

    2011-01-01

    The land subsidence due to groundwater exploitation has an obvious hysteretic nature with respect to the decrease of the under groundwater level,and the uneven settlement often causes ground fissures.To study these important features,a visco-elastic plastic constitutive relationship with consideration of the coupling of seepage and soil deformation is proposed,and a finite element model with variable coefficients based on the Biot's consolidation theory is built.With the groundwater exploitation and the land subsidence control in Cangzhou City,Hebei Province as an example,the variations of the under groundwater level and the development of the land subsidence due to the groundwater exploitation are simulated and ground fissures are predicted by the horizontaldisplacement calculation.The results show that the lag time between the land subsidence and the under groundwater level descent is about a month,and the simulated results of fissures agree well with the observed data.The model can well reveal the characterization of the interaction between the land subsidence and the groundwater exploitation.

  16. The Use of Numerical Modeling to Address Surface and Subsurface Water Contamination due to Fracwater Spills in Larry's Creek, Pennsylvania

    Science.gov (United States)

    Simon, C. A.; Arjmand, S.; Abad, J. D.

    2012-12-01

    Because of its relatively low carbon dioxide emissions, natural gas is considered to be more efficient and environmentally friendly than other non-renewable fuels. As a result of this, among other factors, in recent years natural gas has become one of the world's primary energy sources. In the United States, drilling to extract natural gas has substantially increased over the past few years. In the Marcellus Shale, unconventional gas is currently extracted by using two new techniques: horizontal drilling and hydraulic fracturing. Today, fracking fluids which have been applied as part of the hydraulic fracturing process to fracture the shale rock and release the gas, pose a major environmental concern. These fluids are highly contaminated with radionuclides and toxic metals and any exposure of this highly polluted water to surface water or soil could heavily contaminate the media. The area selected for the current study is the Larry's Creek, located in Lycoming County in Pennsylvania. Larry's Creek Watershed was adversely affected by coal and iron mines activities in the 19th century. Though, the water quality in this creek was considered to be good as of 2006. Recently, oil and gas drilling activities have raised concerns about the creek's water quality again. A major environmental hazard is the freshwater contamination by frac/flowback water. Drilling companies are using impoundments on site to keep fracwater, and to store and evaporate flowback water. However, these ponds may fail or leak due to construction problems and/or accidents. Close to Saladasburg, Larry's Creek's stream was observed running rich with clay in October 19, 2011. Historical measurements show very high turbidity during this period which has raised questions about water contamination by the gas industry activities in the upper stream of the watershed. An interstate watershed agency has reported spills in Wolf Run in different drilling sites in the Larry's Creek basin. The focus of this study

  17. The crystal structure of Haloferax volcanii proliferating cell nuclear antigen reveals unique surface charge characteristics due to halophilic adaptation

    Directory of Open Access Journals (Sweden)

    Morroll Shaun

    2009-08-01

    Full Text Available Abstract Background The high intracellular salt concentration required to maintain a halophilic lifestyle poses challenges to haloarchaeal proteins that must stay soluble, stable and functional in this extreme environment. Proliferating cell nuclear antigen (PCNA is a fundamental protein involved in maintaining genome integrity, with roles in both DNA replication and repair. To investigate the halophilic adaptation of such a key protein we have crystallised and solved the structure of Haloferax volcanii PCNA (HvPCNA to a resolution of 2.0 Å. Results The overall architecture of HvPCNA is very similar to other known PCNAs, which are highly structurally conserved. Three commonly observed adaptations in halophilic proteins are higher surface acidity, bound ions and increased numbers of intermolecular ion pairs (in oligomeric proteins. HvPCNA possesses the former two adaptations but not the latter, despite functioning as a homotrimer. Strikingly, the positive surface charge considered key to PCNA's role as a sliding clamp is dramatically reduced in the halophilic protein. Instead, bound cations within the solvation shell of HvPCNA may permit sliding along negatively charged DNA by reducing electrostatic repulsion effects. Conclusion The extent to which individual proteins adapt to halophilic conditions varies, presumably due to their diverse characteristics and roles within the cell. The number of ion pairs observed in the HvPCNA monomer-monomer interface was unexpectedly low. This may reflect the fact that the trimer is intrinsically stable over a wide range of salt concentrations and therefore additional modifications for trimer maintenance in high salt conditions are not required. Halophilic proteins frequently bind anions and cations and in HvPCNA cation binding may compensate for the remarkable reduction in positive charge in the pore region, to facilitate functional interactions with DNA. In this way, HvPCNA may harness its environment as

  18. Uncertainties in surface mass and energy flux estimates due to different eddy covariance sensors and technical set-up

    Science.gov (United States)

    Arriga, Nicola; Fratini, Gerardo; Forgione, Antonio; Tomassucci, Michele; Papale, Dario

    2010-05-01

    Eddy covariance is a well established and widely used methodology for the measurement of turbulent fluxes of mass and energy in the atmospheric boundary layer, in particular to estimate CO2/H2O and heat exchange above ecologically relevant surfaces (Aubinet 2000, Baldocchi 2003). Despite its long term application and theoretical studies, many issues are still open about the effect of different experimental set-up on final flux estimates. Open issues are the evaluation of the performances of different kind of sensors (e.g. open path vs closed path infra-red gas analysers, vertical vs horizontal mounting ultrasonic anemometers), the quantification of the impact of corresponding physical corrections to be applied to get robust flux estimates taking in account all processes concurring to the measurement (e.g. the so-called WPL term, signal attenuation due to air sampling system for closed path analyser, relative position of analyser and anemometer) and the differences between several data transmission protocols used (analogue, digital RS-232, SDM). A field experiment was designed to study these issues using several instruments among those most used within the Fluxnet community and to compare their performances under conditions supposed to be critical: rainy and cold weather conditions for open-path analysers (Burba 2008), water transport and absorption at high air relative humidity conditions for closed-path systems (Ibrom, 2007), frequency sampling limits and recorded data robustness due to different transmission protocols (RS232, SDM, USB, Ethernet) and finally the effect of the displacement between anemometer and analyser using at least two identical analysers placed at different horizontal and vertical distances from the anemometer. Aim of this experiment is to quantify the effect of several technical solutions on the final estimates of fluxes measured at a point in the space and if they represent a significant source of uncertainty for mass and energy cycle

  19. An integrated assessment framework for land subsidence in delta cities

    Directory of Open Access Journals (Sweden)

    T. H. M. Bucx

    2015-11-01

    Full Text Available In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten by excessive groundwater extraction related to rapid urbanization and population growth. Without change, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other delta (and coastal cities will sink below sea level. Increased flooding and also other widespread impacts of land subsidence result already in damage of billions of dollars per year. In order to gain insight in the complex, multi-sectoral aspects of subsidence, to raise awareness and to support decision making on appropriate adaptation strategies and measures, an Integrated Assessment Framework (IAF for subsidence is introduced, illustrated by several (delta case studies. Based on that a list of 10 generic key issues and possible solutions is presented in order to further develop and support a (generic approach how to deal with subsidence in current and future subsidence-prone areas. For exchange of experiences and knowledge development.on subsidence in deltas the Delta Alliance, a knowledge network of deltas worldwide, can be supportive.

  20. The interaction between land subsidence and urban development in China

    Science.gov (United States)

    Yang, Y.; Wang, R.; Zhou, Y.; Jiang, Y.; Wang, X.

    2015-11-01

    The Yangtze River Delta and North China Plain are experiencing serious land subsidence development and are also the areas that have undergone the fastest urbanization. Rapid urban development inevitably requires more water resources. However, China is a country with small per capita water resources, nonuniform distribution of water resources, and over-exploitation of groundwater - all of which are critical factors contributing to the potential for a land subsidence disaster. In addition, land subsidence has brought about elevation loss, damaged buildings, decreased safety of rail transit projects, lowered land value, and other huge economic losses and potential safety hazards in China. In this paper, Beijing, a typical northern Chinese city deficient in water, is taken as an example to explore (a) the problems of urban development, utilization of water resources, and land subsidence development; (b) the harm and influence of land subsidence hazards on urban construction; and (c) the relationship between urban development and land subsidence. Based on the results, the author has predicted the trend of urban development and land subsidence in Beijing and puts forward her viewpoints and suggestions.

  1. An integrated assessment framework for land subsidence in delta cities

    Science.gov (United States)

    Bucx, T. H. M.; van Ruiten, C. J. M.; Erkens, G.; de Lange, G.

    2015-11-01

    In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten by excessive groundwater extraction related to rapid urbanization and population growth. Without change, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other delta (and coastal) cities will sink below sea level. Increased flooding and also other widespread impacts of land subsidence result already in damage of billions of dollars per year. In order to gain insight in the complex, multi-sectoral aspects of subsidence, to raise awareness and to support decision making on appropriate adaptation strategies and measures, an Integrated Assessment Framework (IAF) for subsidence is introduced, illustrated by several (delta) case studies. Based on that a list of 10 generic key issues and possible solutions is presented in order to further develop and support a (generic) approach how to deal with subsidence in current and future subsidence-prone areas. For exchange of experiences and knowledge development.on subsidence in deltas the Delta Alliance, a knowledge network of deltas worldwide, can be supportive.

  2. Benzene on Cu(111): II. Molecular assembly due to Lateral van der Waals and Surface-State-Mediated Indirect Interactions

    Science.gov (United States)

    Hyldgaard, Per; Berland, Kristian; Einstein, T. L.

    2010-03-01

    Experiments show that benzene condenses into two different structural phases: a compact and a sparse phase, both of approximately hexagonal symmetry. The vdW-DF calculations demonstrate that the denser benzene-overlayer phase, with lattice constant 6.74 ,s due to direct benzene-benzene vdW attraction. The structure of the second, sparser phase, with lattice spacing 10.24 ,s attributed to the indirect electronic interactions mediated by the well-known metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbatively the asymptotic form of this indirect interaction. Our extended vdW-DF scheme---which combines calculations of molecular physisorption, of direct intermolecular vdW coupling, and of indirect electronic interactions between the molecular adsorbates---accounts well for the structural phases of benzene on Cu(111). Our preliminary vdW-DF study of acene and quinone interactions provides building blocks for modeling of anthraquinone assembly on Cu(111).footnotetextG. Pawin, , L. Bartels, Science 313 (2006) 961

  3. Structural, chemical surface and transport modifications of regenerated cellulose dense membranes due to low-dose {gamma}-radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.I. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain); Heredia-Guerrero, J.A., E-mail: jose.alejandro@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-Universidad de Sevilla, Avda, Americo Vespuccio 49, 41092 Sevilla (Spain); Galan, P. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain); Benitez, J.J. [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-Universidad de Sevilla, Avda, Americo Vespuccio 49, 41092 Sevilla (Spain); Benavente, J. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain)

    2011-04-15

    Research highlights: {yields} Low dose {gamma}-radiation causes slight structural, chemical and morphological changes on regenerated cellulose films. {yields} Induced structural changes increase the fragility of irradiated films. {yields} Structural modifications reduce ion permeability of films. - Abstract: Modifications caused in commercial dense regenerated cellulose (RC) flat membranes by low-dose {gamma}-irradiation (average photons energy of 1.23 MeV) are studied. Slight structural, chemical and morphological surface changes due to irradiation in three films with different RC content were determined by ATR-FTIR, XRD, XPS and AFM. Also, the alteration of their mechanical elasticity has been studied. Modification of membrane performance was determined from solute diffusion coefficient and effective membrane fixed charge concentration obtained from NaCl diffusion measurements. Induced structural changes defining new and effective fracture propagation directions are considered to be responsible for the increase of fragility of irradiated RC membranes. The same structural changes are proposed to explain the reduction of the membrane ion permeability through a mechanism involving either ion pathways elongation and/or blocking.

  4. Spatial and Temporal Analysis of Mexico City Subsidence by Means of Interferometric Techniques

    Science.gov (United States)

    Lopez-Quiroz, P.; Tupin, F.; Briole, P.; Doin, M.; Nicolas, J.

    2007-05-01

    In Mexico city, water over-consumption leads to subsidence. Before the Spanish conquest, the southern part of the Mexico Valley, an endoreic basin surrounded by mountains, was filled by a large lake. Flooding problems oblige conquerors to dry the lakes, which by now have almost completely disappeared and have been replaced by buildings. The simplified hydrogeologic structure of Mexico Valley includes a superficial 50 to 300 m thick lacustrine aquitard overlying a thicker aquifer made of alluvial deposits. The aquitard layer plays a crucial role in the subsidence process due to the very high compressibility of its clay deposits separated by a less compressible sand layer where the biggest buildings are anchored. The aquifer over-exploitation leads to a depression of its piezometric level, inducing water downwards flow in the clays, yielding compaction and subsidence (Rivera, 1990). In order to quantitatively link subsidence to water pumping, the Mexico city subsidence needs to be mapped and analyzed through space and time. It will help identify possible variations related with seasonal recharge, anchored and non anchored buildings, old and new pumping areas with varying clay compressibility through time due to consolidation (Rivera, 1990, Ortega-Guerrero et al., 1999). Radar interferometry (InSAR, Interferometric Synthetic Aperture Radar) has been successfully applied to map subsidence caused by water pumping (e. g., Amelung et al., 2000). It uses two repeated SAR acquisitions to obtain distance measurements. After geometrical corrections, the interferometric phase contains deformation information as well as residual orbital and topographic errors and atmospheric delays. A previous work using levelling, interferometry and GPS techniques over Mexico city showed that the location of the maximum subsidence rates (about 400 mm/yr) has changed and moved from the downtown area to the east of the city over a 50 years interval (Cabral-Cano et al., 2006). In this previous

  5. Time series analysis of Mexico City subsidence constrained by radar interferometry

    Science.gov (United States)

    Doin, Marie-Pierre; Lopez-Quiroz, Penelope; Yan, Yajing; Bascou, Pascale; Pinel, Virginie

    2010-05-01

    In Mexico City, subsidence rates reach up to 40 cm/yr mainly due to soil compaction led by the over exploitation of the Mexico Basin aquifer. The Mexico Valley, an endoreic basin surrounded by mountains, was in the past covered by large lakes. After the Spanish conquest, the lakes have almost completely disappeared, being progressively replaced by buildings of the current Mexican capital. The simplified hydrogeologic structure includes a superficial 50 to 300 m thick lacustrine aquitard overlying a thicker aquifer made of alluvial deposits. The aquitard layer plays a crucial role in the subsidence process due to the extremely high compressibility of its clay deposits separated by a less compressible sand layer where the biggest buildings of the city are anchored. The aquifer over-exploitation leads to a large scale 30m depression of its piezometric level, inducing water downwards flow in the clays, yielding compaction and subsidence. In order to quantitatively link subsidence to water pumping, the Mexico city subsidence needs to be mapped and analyzed through space and time. We map its spatial and temporal patterns by differential radar interferometry, using 38 ENVISAT images acquired between end of 2002 and beginning of 2007. We employ both a Permanent Scatterer (PS) and a small baseline (SBAS) approach. The main difficulty consists in the severe unwrapping problems mostly due to the high deformation rate. We develop a specific SBAS approach based on 71 differential interferograms with a perpendicular baseline smaller than 500 m and a temporal baseline smaller than 9 months, forming a redundant network linking all images: (1) To help the unwrapping step, we use the fact that the deformation shape is stable for similar time intervals during the studied period. As a result, a stack of the five best interferograms can be used to reduce the number of fringes in wrapped interferograms. (2) Based on the redundancy of the interferometric data base, we quantify the

  6. Subsidence history of the city of Morelia, Mexico based on InSAR images processed as time series

    Science.gov (United States)

    Jaramillo, S. H.; Suárez, G.; López-Quiroz, P.

    2012-04-01

    The city of Morelia in central Mexico sits on lacustrine and fluvio-lacustrine deposits. Subsidence due to the extraction of water from the subsoil is evidenced by the presence of differential soil compaction, causing faulting and cracking of the ground and adjacent constructions. In order to study the subsidence history of the past nine years, twenty-eight ENVISAT Synthetic Aperture Radar (SAR) images acquired between May 2003 and September 2010 were processed using ROI_PAC. All scenes are descending orbit images. The resulting interferograms were filtered using an adaptive filter and, in order to increase coherence and signal-to-noise ratio, they were unwrapped using the "branch-cut" algorithm. A subset of the resulting interferograms was selected based on the following criteria. Only interferograms with spatial baseline of less than 400 m and a temporal baseline of less than 420 days were considered. The primary objective of our work was to determine the temporal evolution of the subsidence in different parts of the city. To this end, selected pixels are inverted in an independent manner from neighbouring pixels using a time series analysis. Preliminary results suggest that the central part of the basin, near the fault known as the "Central Camionera", the subsidence is almost constant with a value of 3 to 4 cm/yr until 2008. From this date on, the subsidence rates increase to values with an average of 7 to 8 cm/yr. This increase in the subsidence rate is clearly appreciated in the appearance of two clearly visible circular patterns from 2008 to 2010. Currently, an inversion is being conducted to obtain the overall subsidence history of the basin.

  7. 试论湖相高频旋回水下间断面的成因:揭示湖盆短期沉降过程的突破口%Brief discussion about formation cause of underwater discontinuity surface in lacustrine high-frequency cycle: Breakthrough of revealing the short-term subsidence of lake basin

    Institute of Scientific and Technical Information of China (English)

    王冠民; 吴智平; 陈清华

    2012-01-01

    High-frequency cycle of upward-shallowing often develops in lake facies.Underwater discontinuity surface,located at the bottom of cycle,above that paleobathymetry rapidly increases.In continental sequence stratigraphy study,this kind of discontinuity surface is usually directly attributed to ancient lake flooding caused by climate change and underwater non-depositional surface formed by source back.However,this understanding is still difficult to get a satisfactory explanation,and it seems more reasonable if it is classified as results of the basin's short-cycle intermittent tectonic subsidence.The research of underwater discontinuity surface's formation cause in lacustrine high-frequency cycle,not only further explore the basin's short-period tectonic activity patterns and its influence on lake sedimentation in the high-frequency cycle,but provide research base for better application of Milankovitch cycle theory in lake facies.%在湖相条件下,常发育沉积水体单一向上变浅的高频旋回,旋回底部为水下间断面,间断面之上的古水深迅速增大。在陆相层序地层学研究中,常将这类间断面直接归为古气候变化引起湖泛和物源后退形成的水下无沉积作用面。但这种认识目前还难以得到圆满的解释,而如果将其归为盆地短周期的间歇性构造沉降成因似乎显得更为合理。针对湖相高频旋回水下间断面的成因研究,不仅可以进一步探讨盆地短周期的构造活动方式及其对湖相高频旋回沉积过程的影响,也为在湖相条件下更好地应用米兰柯维奇旋回理论提供研究基础。

  8. Land Subsidence and Aquifer-System Compaction in the Tucson Active Management Area, South-Central Arizona, 1987-2005

    Science.gov (United States)

    Carruth, Rob; Flynn, Pool; Donald, R.; Anderson, Carl E.

    2007-01-01

    The U.S. Geological Survey monitors land subsidence and aquifer-system compaction caused by ground-water depletion in Tucson Basin and Avra Valley - two of the three alluvial basins within the Tucson Active Management Area. In spring 1987, the Global Positioning System was used to measure horizontal and vertical positions for bench marks at 43 sites to establish a network for monitoring land subsidence in Tucson Basin and Avra Valley. Between 1987 and 2005, the original number of subsidence monitoring stations was gradually increased to more than 100 stations to meet the need for information in the growing metropolitan area. Data from approximately 60 stations common to the Global Positioning System surveys done after an initial survey in 1987 are used to document land subsidence. For the periods of comparison, average land-surface deformation generally is less than the maximum subsidence at an individual station and takes into account land-surface recovery from elastic aquifer-system compaction. Between 1987 and 1998, as much as 3.2 inches of subsidence occurred in Tucson Basin and as much as 4 inches of subsidence occurred in Avra Valley. For the 31 stations that are common to both the 1987 and 1998 Global Positioning System surveys, the average subsidence during the 11-year period was about 0.5 inch in Tucson Basin and about 1.2 inches in Avra Valley. For the approximately 60 stations that are common to both the 1998 and 2002 Global Positioning System surveys, the data indicate that as much as 3.5 inches of subsidence occurred in Tucson Basin and as much as 1.1 inches of subsidence occurred in Avra Valley. The average subsidence for the 4-year period is about 0.4 inch in Tucson Basin and 0.6 inch in Avra Valley. Between the 2002 and the 2005 Global Positioning System surveys, the data indicate that as much as 0.2 inch of subsidence occurred in Tucson Basin and as much as 2.2 inches of subsidence occurred in Avra Valley. The average subsidence for the 3-year

  9. Shallow Faulting in Morelia, Mexico, Based on Seismic Tomography and Geodetically Detected Land Subsidence

    Science.gov (United States)

    Cabral-Cano, E.; Arciniega-Ceballos, A.; Vergara-Huerta, F.; Chaussard, E.; Wdowinski, S.; DeMets, C.; Salazar-Tlaczani, L.

    2013-12-01

    Subsidence has been a common occurrence in several cities in central Mexico for the past three decades. This process causes substantial damage to the urban infrastructure and housing in several cities and it is a major factor to be considered when planning urban development, land-use zoning and hazard mitigation strategies. Since the early 1980's the city of Morelia in Central Mexico has experienced subsidence associated with groundwater extraction in excess of natural recharge from rainfall. Previous works have focused on the detection and temporal evolution of the subsidence spatial distribution. The most recent InSAR analysis confirms the permanence of previously detected rapidly subsiding areas such as the Rio Grande Meander area and also defines 2 subsidence patches previously undetected in the newly developed suburban sectors west of Morelia at the Fraccionamiento Del Bosque along, south of Hwy. 15 and another patch located north of Morelia along Gabino Castañeda del Rio Ave. Because subsidence-induced, shallow faulting develops at high horizontal strain localization, newly developed a subsidence areas are particularly prone to faulting and fissuring. Shallow faulting increases groundwater vulnerability because it disrupts discharge hydraulic infrastructure and creates a direct path for transport of surface pollutants into the underlying aquifer. Other sectors in Morelia that have been experiencing subsidence for longer time have already developed well defined faults such as La Colina, Central Camionera, Torremolinos and La Paloma faults. Local construction codes in the vicinity of these faults define a very narrow swath along which housing construction is not allowed. In order to better characterize these fault systems and provide better criteria for future municipal construction codes we have surveyed the La Colina and Torremolinos fault systems in the western sector of Morelia using seismic tomographic techniques. Our results indicate that La Colina Fault

  10. InSAR Used for Subsidence Monitoring of Mining Area OKR, Czech Republic

    Science.gov (United States)

    Lazecky, Milan

    2010-03-01

    The abilities of InSAR processing techniques to detect and monitor subsidence of mining areas were already proved in several works, e.g. of Dr. Perski that used them in Poland. As an ESA project of VSB-TU Ostrava using data from ERS 1,2 and Envisat ASAR, the InSAR has been applied also for the Northern Moravian OKR region in Czech Republic, a region with a long black coal mining history. Mining activities in this area have caused damages and destructions of many buildings, tramlines etc. The problem is still actual, even that only 4 mines are active, since 2007. Via the InSAR processing, an evolution of subsidence during last 10 years is monitored using the Doris software. Due to highly decorrelated interferograms created from newer data (since 2001), the actual state is hardly interpretable though. The critical subsiding objects were detected by pointwise multitemporal InSAR techniques (MT- InSAR) - the permanent scatterers and small baselines methods using the StaMPS software. The results were compared with the in-situ levelling revealing that the estimated rate of subsidence was underestimated. Only the ERS-2 data from period 1999-2000 were successfully used in these advanced InSAR techniques to achieve some reasonable results. Because of gyroscopes failure of ERS-2, the data since January 2001 couldn't be processed successfully by StaMPS due to big differences in the Doppler centroid frequencies of each images - an abortive result of a small baselines method attempt can be presented. Because of used long- wall mining method, that evokes spatial movement of subsidence epicenters in time, a longer time period of dataset usable in MT-InSAR would decrease the processing merit (the character of subsidence in the area is not pointwise in longer time period). This project will continue with a processing of newer datasets to achieve a complete overview of terrain changes in the mining area during the last decade.

  11. Effects of anthropogenic land-subsidence on inundation dynamics: the case study of Ravenna, Italy

    Directory of Open Access Journals (Sweden)

    F. Carisi

    2016-05-01

    Full Text Available Can differential land-subsidence significantly alter river flooding dynamics, and thus flood risk in flood prone areas? Many studies show how the lowering of the coastal areas is closely related to an increase in the flood-hazard due to more important tidal flooding and see level rise. The literature on the relationship between differential land-subsidence and possible alterations to riverine flood-hazard of inland areas is still sparse, although several geographical areas characterized by significant land-subsidence rates during the last 50 years experienced intensification in both inundation magnitude and frequency. We investigate the possible impact of a significant differential ground lowering on flood hazard over a 77 km2 area around the city of Ravenna, in Italy. The rate of land-subsidence in the study area, naturally in the order of a few mm year−1, dramatically increased up to 110 mm year−1 after World War II, primarily due to groundwater pumping and gas production platforms. The result was a cumulative drop that locally exceeds 1.5 m. Using a recent digital elevation model (res. 5 m and literature data on land-subsidence, we constructed a ground elevation model over the study area in 1897 and we characterized either the current and the historical DEM with or without road embankments and land-reclamation channels in their current configuration. We then considered these four different topographic models and a two-dimensional hydrodynamic model to simulate and compare the inundation dynamics associated with a levee failure scenario along embankment system of the river Montone, which flows eastward in the southern portion of the study area. For each topographic model, we quantified the flood hazard in terms of maximum water depth (h and we compared the actual effects on flood-hazard dynamics of differential land-subsidence relative to those associated with other man-made topographic alterations, which resulted to be much

  12. Equivalent materials simulation experimental study on bed separations developing and mining subsidence in constant humidity and constant temperature conditions

    Institute of Scientific and Technical Information of China (English)

    FU Zhi-liang; WANG Su-hua; GAO Yan-fa

    2008-01-01

    A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advancing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing; the maximum value of bed separations is 0.31~0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.

  13. Equivalent materials simulation experimental study on bed separations developing and mining subsidence in constant humidity and constant temperature conditions

    Institute of Scientific and Technical Information of China (English)

    FU Zhi-liang; WANG Su-hua; GAO Yan-fa

    2008-01-01

    A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation. The overburden deformation and the developing of bed separations with working face advanc-ing was simulated by a new model. The results show that the maximum value of bed separations moved forward gradually along with the working face advancing; the maxi-mum value of bed separations is 0.31 ~0.50 times of mining thickness. The key strata have a great influence upon surface subsidence during the overburden movement process. The mechanics parameters of new experiment are fitted with results in fields perfectly.

  14. Challenges related to flotation cleaning of oil shales. Issues due to compositional and surface features and post-grinding surface behavior

    Directory of Open Access Journals (Sweden)

    Altun N. Emre

    2016-01-01

    Full Text Available Oil shale is an important energy resource alternative. Despite its recognition as an unconventional oil source, oil shale is also considered as an important solid fossil fuel alternative to coal and lignites due to the solid form and remarkable extent of organic content. Utilization possibilites, similar to coal and lignites, have been considered in the past decades and direct use of oil shales in thermal power production has been possible in countries like Estonia and China. In the perspective of utilization of oil shales in a similar manner to coal and lignites, problems and restrictions related to the inorganic ash-making and potentially pollutant constituents are applied. In this respect, cleaning of this important energy source through mineral processing methods, particularly by flotation, is an outstanding option. However, on the basis of unique features and distinctive characteristics, treatment of oil shales like a type of coal is a big perception and may be highly misleading. This paper discusses specific challenges regarding flotation behavior of oil shales with reference to the surface characteristics and behavior of oil shale entities – probably the most important aspect that determines the efficiency and success of the flotation based cleaning process.

  15. The influences of the tectonic subsidence and the siltation on the situation of preventing flood disasters in the Dongting Lake area

    Institute of Scientific and Technical Information of China (English)

    LAIHongzhou; MODuowen

    2004-01-01

    With the long-term data of the geodetic sea level measurements undertaken in the Dongting Basin and the recent sediment data of Dongting Lake, we analyze the tectonic subsidence rate of the Dongting Basin and the sedimentary rate of Dongting Lake. From the point of view of geomorphology and hydrogeology, we distinguish the two different spatial concepts between "the basin of Dongting Lake" and "the Dongting Basin". Then, we discuss the influences of the tectonic subsidence and the siltation on the levees and the space of storing flood. The better quality of levees is required due to the tectonic subsidence and the siltation, and the difficulties of preventing flood disasters are increasing.The space of storing flood is not affected by the tectonic subsidence, but by the siltation. At present,the sedimentary rate of Dongting Lake is higher than the tectonic subsidence rate of the Dongting Basin. The tectonic subsidence capacity of the Dongting Basin counteracts a part of sedimentary capacity, and the shrinking tendency of Dongting Lake is restrained to a certain extent, but the tectonic subsidence is harmful to the situation of preventing flood disasters in the Dongting Lake area.

  16. Land subsidence in Tianjin for 2015 to 2016 revealed by the analysis of Sentinel-1A with SBAS-InSAR

    Science.gov (United States)

    Guo, Jiming; Hu, Jiyuan; Li, Bing; Zhou, Lv; Wang, Wei

    2017-04-01

    It has been suggested that Tianjin, China, has significant land subsidence due to excessive extraction of water. Although it is presently under control, the land subsidence around Tianjin suburbs in recent years should not be ignored. However, existing research work on land subsidence is based on traditional synthetic aperture radar satellite images in which the research time spans are mainly before 2012. An advanced time-series method, namely small baselines subset (SBAS) technique, is applied to a total of 27 Sentinel-1A images over Tianjin acquired between May 31, 2015, and May 13, 2016, to derive the subsidence magnitude and distribution of Tianjin. Furthermore, the overall and quantitative validations of SBAS-derived results are implemented. First, the overall subsidence distribution derived by SBAS is compared with the annual report of land subsidence in Tianjin 2015, which shows the same subsidence trend and distribution. Then, 44 benchmarks and 2 continuously operating reference station datasets, i.e., CH01 and XQYY, are processed to provide a specific validation of SBAS-derived results of Sentinel-1A. Finally, through investigation, an interpretation from two aspects of groundwater extraction and geological structures of the surrounding Wangqingtuo settlement funnel area is given.

  17. Evaluation of Subterranean Subsidence at Seal Beach National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this study was to determine the amount of subsurface subsidence at Naval Weapons Station Seal Beach (NWSSB) areas which include Seal Beach National...

  18. Subsidence of the femoral prosthesis. A stereophotogrammetric evaluation.

    Science.gov (United States)

    Chafetz, N; Baumrind, S; Murray, W R; Genant, H K; Korn, E L

    1985-12-01

    A quantitative three-dimensional measurement method, radiographic stereophotogrammetry (SPG), was employed to assess the relation between early subsidence of the femoral prosthesis after total hip arthroplasty (THA) and subsequent clinical course. The SPG technique and the authors' error control mechanisms are described in 15 patients in the early postoperative period, and the findings are correlated with those of follow-up clinical examinations. Among the 12 patients who remained clinically asymptomatic with respect to pain, only one had an SPG estimate of subsidence in excess of 1 mm at any point in time. Each of the three patients who later became symptomatic had SPG estimates of subsidence in excess of 1.75 mm within six months of the operation. Thus far, the patient with the largest estimate of subsidence is the only one who required surgical revision.

  19. Water quality variation of mining-subsidence lake during the initial stage: cases study of Zhangji and Guqiao Mines

    Institute of Scientific and Technical Information of China (English)

    FAN Tina-yu; YAN Jia-ping; WANG Shun; ZHANG Bing; RUAN Shu-xian; ZHANG Mei-li; LI Shou-qin; CHEN Yong-chun; LIU Jin

    2012-01-01

    Four quarters' water collecting and monitoring samples were done in the mining subsidence lakes of different water storing periods (2 to 7 years),considering the water storing time and pollution sources state of the subsidence lakes.The following indexes were discussed such as organic indexes (TOC,CODMn,BOD,COD),nutrient salts (TN,NH4+,NO3-,NO2-,Kjeldahl Nitrogen,TP,PO43-),etc.It is shown that water quality of the mining subsidence lake during the initial stage (2 years to 7 years) can stay relatively stable with a fluctuation during different quarters in a year,which can reach class Ⅲ or Ⅳ of the Surface Water Environmental Quality Standard.

  20. Numerical and experimental study of strata behavior and land subsidence in an underground coal gasification project

    Science.gov (United States)

    Sirdesai, N. N.; Singh, R.; Singh, T. N.; Ranjith, P. G.

    2015-11-01

    Underground Coal Gasification, with enhanced knowledge of hydrogeological, geomechanical and environmental aspects, can be an alternative technique to exploit the existing unmineable reserves of coal. During the gasification process, petro-physical and geomechanical properties undergo a drastic change due to heating to elevated temperatures. These changes, caused due to the thermal anisotropy of various minerals, result in the generation of thermal stresses; thereby developing new fracture pattern. These fractures cause the overhead rock strata to cave and fill the gasification chamber thereby causing subsidence. The degree of subsidence, change in fluid transport and geomechanical properties of the rock strata, in and around the subsidence zone, can affect the groundwater flow. This study aims to predict the thermo-geomechanical response of the strata during UCG. Petro-physical and geomechanical properties are incorporated in the numerical modelling software COMSOL Multiphysics and an analytical strength model is developed to validate and further study the mechanical response and heat conduction of the host rock around the gasification chamber. Once the problems are investigated and solved, the enhanced efficiency and the economic exploitation of gasification process would help meet country's energy demand.

  1. Changes in albumin/platelet interaction with an artificial surface--due to a antibiotics, pyridoxal phosphate, and lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chandy, T.; Sharma, C.P.

    1988-04-01

    Protein adsorption and platelet adhesion are two important biological processes arising at the blood prosthetic interface. The effect of certain antibiotics, namely, neomycin, gentamicin, ampicillin, penicillin-G, and streptomycin to modulate the albumin polycarbonate surface interaction was investigated using /sup 125/I albumin from a protein mixture in the presence and absence of isolated calf lymphocytes. This study also demonstrated the changes in platelet-surface adhesion with these antibiotics. The effect of pyridoxal phosphate to modulate the red blood cell-mediated platelet-surface attachment was also attempted. It appears from pyridoxal phosphate studies that pyridoxal 5'-phosphate (PLP) could modify the surface-platelet attachment. It also inhibited the fibrinogen-induced platelet adhesion. It seems, the addition of antibiotics to the polymerprotein system increased the level of surface-bound albumin variably whereas lymphocytes incubated in the medium did not affect the surface-albumin concentration with time course. These antibiotics also inhibited the surface-induced platelet adhesion to variable degrees. Our earlier studies have indicated that certain antibiotics or antiplatelet drugs can inhibit the fibrinogen binding to an artificial surface. Therefore, it may be possible that the enhanced albumin-surface concentration or reduced fibrinogen-surface binding, in the presence of these antibiotics, may itself be one of the parameter for a reduced platelet-surface attachment, which may also improve the blood compatibility of the substrate. A better understanding of the mechanism of antibiotics is needed in in vivo conditions to correlate these findings.

  2. Application of InSAR and gravimetric surveys for developing construction codes in zones of land subsidence induced by groundwater extraction: case study of Aguascalientes, Mexico

    Science.gov (United States)

    Pacheco-Martínez, J.; Wdowinski, S.; Cabral-Cano, E.; Hernández-Marín, M.; Ortiz-Lozano, J. A.; Oliver-Cabrera, T.; Solano-Rojas, D.; Havazli, E.

    2015-11-01

    Interferometric Synthetic Aperture Radar (InSAR) has become a valuable tool for surface deformation monitoring, including land subsidence associated with groundwater extraction. Another useful tools for studying Earth's surface processes are geophysical methods such as Gravimetry. In this work we present the application of InSAR analysis and gravimetric surveying to generate valuable information for risk management related to land subsidence and surface faulting. Subsidence of the city of Aguascalientes, Mexico is presented as study case. Aguascalientes local governments have addressed land subsidence issues by including new requirements for new constructions projects in the State Urban Construction Code. Nevertheless, the resulting zoning proposed in the code is still subjective and not clearly defined. Our work based on gravimetric and InSAR surveys is aimed for improving the subsidence hazard zoning proposed in the State Urban Code in a more comprehensive way. The study includes a 2007-2011 ALOS InSAR time-series analysis of the Aguascalientes valley, an interpretation of the compete Bouguer gravimetric anomaly of the Aguascalientes urban area, and the application of time series and gravimetric anomaly maps for improve the subsidence hazard zoning of Aguascalientes City.

  3. Subsidence history and forming mechanism of anomalous tectonic subsidence in the Bozhong depression, Bohaiwan basin

    Institute of Scientific and Technical Information of China (English)

    XIE; XiNong

    2007-01-01

    [1]Li D S.Tectonic framework of the Bohai Gulf and coastal basins.Mar Sci,1982,1:82-93[2]Li S T.Basin geodynamics background of formation of huge petroleum systems (in Chinese).Earth Sci-J China Univ Geosci,2004,29(5):505-512[3]Allen M B,Macdonald D I M,Zhao X,et al.Early Cenozoic two-phase extension and late Cenozoic thermal subsidence and inversion of the Bohai basin,northern China.Mar Petrol Geol,1997,14(7/8):951-972[4]Gong Z S,Wang G C.Neotectonism and late hydrocarbon accumulation in Bohai Sea.Acta Pet Sin (in Chinese),2001,22(2):1-8[5]Hu S B,O'Sullivan P B,Raza A,et al.Thermal history and tectonic subsidence of the Bohai Basin,northern China:a Cenozoic rifted and local pull-apart basin.Phys Earth Planet Int,2001,126:221-235[6]Ren J Y,Tamaki K,Li S T,et al.Late Mesozoic and Cenozoic rifting and its dynamic setting in Eastern China and adjacent areas.Tectonophysics,2002,344:175-205[7]Li D S.Tectonics of Petroliferous Basins in China (in Chinese).Beijing:Petroleum Industry Press,2002.674[8]Xu J,Ma Z J,Deng Q D,et al.Regional tectonic conditions for intensive subsidence of the middle Bohai Sea since Oligocene.Acta Pet Sin (in Chinese),2004,25(5):11-16[9]Sclater J G,Christie P A F.Continental stretching:an explanation of the post Mid-Cretaceous subsidence of the central North Sea basin.J Geophys Res,1980,85:3711-3739[10]Xie X N,Müller R D,Li S T,et al.Origin of anomalous tectonic subsidence along the northern South China Sea Margin and its relationship to dynamic topography.Mar Pet Geol,2006,23(7):745-765[11]White N.Recovery of strain-rate variation from inversion of subsidence data.Nature,1993,366(6454):449-452[12]White N.An inverse method for determining lithosphere strain rate variation on geological time scales.Earth Planet Sci Lett,1994,122:351-371[13]Xie X N,Bethke C M,Li S T,et al.Overpressure and Petroleum generation and accumulation in the Dongying Depression of the Bohaiwan Basin,China.Geofluids,2001,1(4):257-271[14]Hall R.Reconstructing Cenozoic SE

  4. The investigation of dangerous geological processes resulting in land subsidence while designing the main gas pipeline in South Yakutia

    Science.gov (United States)

    Strokova, L. A.; Ermolaeva, A. V.; Golubeva, V. V.

    2016-09-01

    The number of gas main accidents has increased recently due to dangerous geological processes in underdeveloped areas located in difficult geological conditions. The paper analyses land subsidence caused by karst and thermokarst processes in the right of way, reveals the assessment criteria for geological hazards and creates zoning schemes considering the levels of karst and thermorkarst hazards.

  5. Adaptation and mitigation of land subsidence in Semarang

    Science.gov (United States)

    Andreas, Heri; Abidin, Hasanuddin Z.; Gumilar, Irwan; Sidiq, Teguh Purnama; Yuwono, Bambang

    2017-07-01

    Land subsidence is not a new phenomenon for Semarang. Some report said the subsidence in Semarang probably is occurring for more than 100 years. Based on the leveling surveys conducted by the Centre of Environmental Geology from 1999 to 2003 it was found that relatively large subsidence was detected around Semarang Harbor, Pondok Hasanuddin, Bandar Harjo and around Semarang Tawang Railway station, with the rates ranging from 1 to 17 cm/year. Results derived from GPS show that land subsidence in Semarang has spatial and temporal variations. In general, subsidence rates in Semarang have an average rate of about 6 to 7 cm/year, with maximum rates that can go up to 14-19 cm/year at certain locations. The impact of land subsidence in Semarang can be seen in several forms, such as the wider expansion of (coastal) flooding areas "rob", cracking of buildings and infrastructure, and increased inland sea water intrusion. It also badly influences the quality and amenity of the living environment and life (e.g. health and sanitation condition) in the affected areas. In the case of Semarang, adaptation and mitigation are considered very important. We have been done some investigations to this area by field observations (mapping the flooded area, mapping the infrastructure problems, interviewing people and seeing the adaptations, conduct GPS measurement to see deformation, etc.), gather information from Government, from digital media, etc., and we noticed people increased their house, and the local goverment elevated the road and the bridge, etc. regulary over less decade periode as part of adaptation. We also noticed the Central Goverment built the dyke and pumping station. Our conclusions said that the adaptation only made temporaly since significant land subsidence keep coming and worsening by the sea level which is keep rising. Another conclusion, so far we have seen lack of mitigation program, monitoring or even inevective mitigation in Semarang related to this subsidence

  6. Characterizing land subsidence mechanisms as a function of urban basin geohazards using space geodesy

    Science.gov (United States)

    Bawden, G. W.

    2016-12-01

    Land subsidence in urban basins will likely become a more significant geohazard in many of the global sedimentary basins as population growth, resource availability, and climate change compound natural and anthropogenic contributors that influence basin elevation. Coastal basins are at the greatest risk where land subsidence is additive to sea level rise, thereby increasing the rate of exposure to coastal populations. Land surface elevation change is a function of many different parameters, including: elastic and inelastic surface response to managed and natural groundwater levels; anthropogenic activities (hydrocarbon extraction, wastewater injection, fracking, geothermal production, and mass redistribution); local tectonic deformation and regional tectonic drivers (such as repeated uplift and subsidence cycles above subduction zones); climate change (influencing the timing, magnitude, nature and duration of seasonal/annual precipitation and permafrost extent); material properties of the basin sediments (influencing susceptibility to soil compaction, oxidization, and dissolution); post glacial rebound; isostatic flexure associated with sea-level and local mass changes; and large scale gravitational processes (such as growth faults and landslides). Geodetic measurements, such as InSAR and GPS, help track spatial and temporal changes in both relative and absolute basin elevation thereby helping to characterize the mechanism(s) driving the geohazards. In addition to a number of commercial radar satellites, European Space Agency's Sentinel-1a/b satellites are beginning to provide a wealth of data over many basin targets with C-band (5.5 cm wavelength). The NISAR (NASA-ISRO Synthetic Aperture Radar) L-band (24 cm wavelength) mission (anticipated 2021 launch) will image nearly every basin globally every 12 days and data from the mission will help characterize land subsidence and many other solid-Earth and hydrologic geohazards that impact urban basins.

  7. Land subsidence monitoring by D-InSAR technique

    Institute of Scientific and Technical Information of China (English)

    Fan Hongdong; Deng Kazhong; Ju Chengyu; Zhu Chuanguang; Xue Jiqun

    2011-01-01

    Nowadays,the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) technique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values,but the analysis of subsidence process and mechanism are insufficient.In order to resolve these problems,6 scenes of ERS1/2 images captured during 1995 and 2000 in a certain place of Jiangsu province were selected to obtain the subsidence and velocities in three time segments by “two-pass” DInSAR method.Then the relationships among distributions of pumping wells,exploitation quantity of groundwater,and confined water levels were studied and the subsidence mechanism was systematically analyzed.The results show that using D-InSAR technique to monitor the deformation of large area can obtain high accuracies,the disadvantages of classical observation methods can be remedied and there is a linear relationship among the velocities of land subsidence,the water level and the exploitation quantity.

  8. Comparison of P-Wave and S-Wave Reflection Surveying Effectiveness for Detection of Mine-Related Subsidence Activity Beneath a Heavily Traveled Roadway

    Science.gov (United States)

    Guy, E. D.; Daniels, J. J.

    2002-12-01

    We acquired high-resolution multicomponent seismic reflection data along an undermined 2200 ft (671 m) section of Interstate highway 70 (I-70) in eastern Ohio, in order to identify areas of active subsidence or soil piping into subsurface collapse features. This paper presents results from research conducted: 1) to investigate potential advantages and disadvantages associated with near-surface P- and S-wave reflection surveys, and 2) to determine the subsidence detection potential of common-mode P- and S-wave data components acquired in the study area. P-wave data have traditionally been acquired during shallow reflection surveys, however, the number of reports concerning shallow S-wave surveys is relatively small, and very few reports concerning the concurrent acquisition and analysis of P- and S-wave reflection data exist. Although S-wave reflections from the top-of-bedrock (located above the coal mine and targeted for subsidence detection purposes) were consistently observed in both XX component (inline-inline, SV-SV) and YY component (crossline-crossline, SH-SH) data, surface wave noise resulted in the optimum reflection window of XX data being relatively narrow. Stacks produced using YY data had a higher signal-to-noise ratio and better imaged the target horizon than those produced using XX data. Whereas S-waves were relatively insensitive to changes in overburden moisture content, P-wave reflections from the top-of-saturated-overburden (located above bedrock) were recorded in ZZ component (vertical-vertical, P-P) data. The arrival times of P-wave reflections and the characteristics of the recorded noise modes made it difficult to process and use P-wave reflections from this interface. P-wave events from deeper impedance contrasts were not observed in field data due to several factors: surface wave and air wave noise, a high P-wave reflection coefficient at the top-of-saturated-overburden, low P-wave reflection coefficients at deeper interfaces, and

  9. Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960–2014

    OpenAIRE

    2015-01-01

    Observed changes in the surface elevation of the Greenland Ice Sheet are caused by ice dynamics, basal elevation change, basal melt, surface mass balance (SMB) variability, and by compaction of the overlying firn. The last two contributions are quantified here using a firn model that includes compaction, meltwater percolation, and refreezing. The model is forced with surface mass fluxes and temperature from a regional climate model for the period 1960–2014. The model results...

  10. Analysis of spatial correlation between the phenomenon land subsidence and rob (tidal inundation) using sentinel-1 SAR, GPS and geological data in Semarang city-Indonesia

    Science.gov (United States)

    Prasetyo, Yudo; Fahrudin, Islam, Lukman Juhdi Fahri

    2017-07-01

    widespread rob due to the increasing value of land subsidence in Semarang.

  11. Feedback of land subsidence on the movement and conjunctive use of water resources

    Science.gov (United States)

    Schmid, Wolfgang; Hanson, Randall T; Leake, Stanley A; Hughes, Joseph D; Niswonger, Richard G.

    2014-01-01

    The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent flows that also depend on aquifer head and other flow terms. In a test example, flows most affected were stream seepage and evapotranspiration from groundwater (ETgw). Deformation feedback also had an indirect effect on conjunctive surface- and groundwater use components: Changed stream seepage and streamflows influenced surface-water deliveries and returnflows. Changed ETgw affected irrigation demand, which jointly with altered surface-water supplies resulted in changed supplemental groundwater requirements and pumping and changed return runoff. This modeling feature will improve the impact assessment of dewatering-induced land subsidence/uplift (following irrigation pumping or coal-seam gas extraction) on surface receptors, inter-basin transfers, and surface-infrastructure integrity.

  12. Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960-2014

    NARCIS (Netherlands)

    Kuipers Munneke, P.; Ligtenberg, S. R M; Noël, B. P Y; Howat, I. M.; Box, J. E.; Mosley-Thompson, E.; McConnell, J. R.; Steffen, K.; Harper, J. T.; Das, S. B.; Van Den Broeke, M. R.

    2015-01-01

    Observed changes in the surface elevation of the Greenland Ice Sheet are caused by ice dynamics, basal elevation change, basal melt, surface mass balance (SMB) variability, and by compaction of the overlying firn. The last two contributions are quantified here using a firn model that includes compac

  13. Water-gas dynamics and coastal land subsidence over Chioggia Mare field, northern Adriatic Sea

    Science.gov (United States)

    Teatini, Pietro; Baú, Domenico; Gambolati, Giuseppe

    2000-09-01

    A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company. One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth of 1000-1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing a rebound of 0.6-0.7 cm. Résumé. Un important programme de développement portant sur 15 gisements de gaz du nord de l'Adriatique a été récemment soumis au Comité VIA pour l'évaluation de l'impact sur l'environnement du Ministère de l'Environnement, par la société ENI-Agip, la compagnie nationale pétrolière italienne. L'un des plus importants réservoirs est celui de Chioggia Mare, situé à environ 10 km au large du littoral vénitien, à une profondeur de 1000 à 1400 m. La production de gaz prévue pour ce gisement laisse envisager un impact sur la stabilité du trait de côte, avec une

  14. Differential subsidence and its effect on subsurface infrastructure: predicting probability of pipeline failure (STOOP project)

    Science.gov (United States)

    de Bruijn, Renée; Dabekaussen, Willem; Hijma, Marc; Wiersma, Ane; Abspoel-Bukman, Linda; Boeije, Remco; Courage, Wim; van der Geest, Johan; Hamburg, Marc; Harmsma, Edwin; Helmholt, Kristian; van den Heuvel, Frank; Kruse, Henk; Langius, Erik; Lazovik, Elena

    2017-04-01

    Due to heterogeneity of the subsurface in the delta environment of the Netherlands, differential subsidence over short distances results in tension and subsequent wear of subsurface infrastructure, such as water and gas pipelines. Due to uncertainties in the build-up of the subsurface, however, it is unknown where this problem is the most prominent. This is a problem for asset managers deciding when a pipeline needs replacement: damaged pipelines endanger security of supply and pose a significant threat to safety, yet premature replacement raises needless expenses. In both cases, costs - financial or other - are high. Therefore, an interdisciplinary research team of geotechnicians, geologists and Big Data engineers from research institutes TNO, Deltares and SkyGeo developed a stochastic model to predict differential subsidence and the probability of consequent pipeline failure on a (sub-)street level. In this project pipeline data from company databases is combined with a stochastic geological model and information on (historical) groundwater levels and overburden material. Probability of pipeline failure is modelled by a coupling with a subsidence model and two separate models on pipeline behaviour under stress, using a probabilistic approach. The total length of pipelines (approx. 200.000 km operational in the Netherlands) and the complexity of the model chain that is needed to calculate a chance of failure, results in large computational challenges, as it requires massive evaluation of possible scenarios to reach the required level of confidence. To cope with this, a scalable computational infrastructure has been developed, composing a model workflow in which components have a heterogeneous technological basis. Three pilot areas covering an urban, a rural and a mixed environment, characterised by different groundwater-management strategies and different overburden histories, are used to evaluate the differences in subsidence and uncertainties that come with

  15. Subsidence rates at the southern Salton Sea consistent with reservoir depletion

    Science.gov (United States)

    Barbour, Andrew; Evans, Eileen; Hickman, Stephen H.; Eneva, Mariana

    2016-01-01

    Space geodetic measurements from the Envisat satellite between 2003 and 2010 show that subsidence rates near the southeastern shoreline of the Salton Sea in Southern California are up to 52mmyr−1 greater than the far-field background rate. By comparing these measurements with model predictions, we find that this subsidence appears to be dominated by poroelastic contraction associated with ongoing geothermal fluid production, rather than the purely fault-related subsidence proposed previously. Using a simple point source model, we suggest that the source of this proposed volumetric strain is at depths between 1.0 km and 2.4 km (95% confidence interval), comparable to generalized boundaries of the Salton Sea geothermal reservoir. We find that fault slip on two previously imaged tectonic structures, which are part of a larger system of faults in the Brawley Seismic Zone, is not an adequate predictor of surface velocity fields because the magnitudes of the best fitting slip rates are often greater than the full plate boundary rate and at least 2 times greater than characteristic sedimentation rates in this region. Large-scale residual velocity anomalies indicate that spatial patterns predicted by fault slip are incompatible with the observations.

  16. Constraints on the mechanism of long-term, steady subsidence at Medicine Lake volcano, northern California, from GPS, leveling, and InSAR

    Science.gov (United States)

    Poland, Michael P.; Burgmann, Roland; Dzurisin, Daniel; Lisowski, Michael; Masterlark, Timothy; Owen, Susan; Fink, Jonathan

    2006-01-01

    with comparatively smaller horizontal displacements. Thermoelastic contraction of a column of hot rock beneath the volcano cannot reproduce the observed ratio of vertical to horizontal surface displacements. Models that determine deformation due to loading by the volcano and dense intrusions can be made to fit the pattern of vertical displacements by assuming a weak upper crust beneath MLV, though the subsidence rates due to surface loading must be lower than the observed displacements. Tectonic extension is almost certainly occurring based on fault orientations and focal mechanisms, but does not appear to be a major contributor to the observed deformation. We favor a model that includes a combination of sources, including extension and loading of a hot weak crust with thermal contraction of a cooling mass of rock beneath MLV, which are processes that are probably occurring at MLV. Future microgravity surveys and the planned deployment of an array of continuous GPS stations as part of a Plate Boundary Observatory volcano cluster will help to refine this model.

  17. Simulation of regional land subsidence in the southern Yangtze Delta

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Investigation of the deformation characteristics of individual hydrostratigraphic units is the key to construct a regional land subsidence model. All of 12 hydrostratigraphic units in the study area were discussed throughout. On the basis of the measured data of groundwater level, five kinds of changing patterns of groundwater level were deduced and the relationship between the deformation characteris-tics of aquifer units and the corresponding changing patterns of groundwater level was discussed. The study area is 1.7×104 km2, where the geological condition is complex. The changing patterns of groundwater level the hydrostratigraphic units have experienced vary from site to site and from time to time. Consequently, the deformation characteristics of units are sophisticated. An identical hydros-tratigraphic unit may exhibit different deformation characteristics, such as elasticity, elasto-plasticity, visco-elasticity, and visco-elasto-plasticity, at different sites or during different periods, not to mention the different units. The existing models are difficult to describe the complex visco-elasto-plastic con-stitutive law under the condition of land subsidence. So the Merchant’s model was modified to depict the visco-elasto-plastic behavior of units. Then a three-dimensional flow model with variable parame-ters and a vertical one-dimensional subsidence model were constructed and coupled. The coupled model was applied in simulating land subsidence in the southern Yangtze Delta and a satisfactory re-sult was obtained. The simulation results show that the new coupled model can depict the complex geological conditions and describe the developing process of land subsidence very well in the south-ern Yangtze Delta. The new model can surely be used to predict land subsidence in the future, which is very helpful to taking measurements to control land subsidence.

  18. Seismic fragility formulations for segmented buried pipeline systems including the impact of differential ground subsidence

    Energy Technology Data Exchange (ETDEWEB)

    Pineda Porras, Omar Andrey [Los Alamos National Laboratory; Ordaz, Mario [UNAM, MEXICO CITY

    2009-01-01

    Though Differential Ground Subsidence (DGS) impacts the seismic response of segmented buried pipelines augmenting their vulnerability, fragility formulations to estimate repair rates under such condition are not available in the literature. Physical models to estimate pipeline seismic damage considering other cases of permanent ground subsidence (e.g. faulting, tectonic uplift, liquefaction, and landslides) have been extensively reported, not being the case of DGS. The refinement of the study of two important phenomena in Mexico City - the 1985 Michoacan earthquake scenario and the sinking of the city due to ground subsidence - has contributed to the analysis of the interrelation of pipeline damage, ground motion intensity, and DGS; from the analysis of the 48-inch pipeline network of the Mexico City's Water System, fragility formulations for segmented buried pipeline systems for two DGS levels are proposed. The novel parameter PGV{sup 2}/PGA, being PGV peak ground velocity and PGA peak ground acceleration, has been used as seismic parameter in these formulations, since it has shown better correlation to pipeline damage than PGV alone according to previous studies. By comparing the proposed fragilities, it is concluded that a change in the DGS level (from Low-Medium to High) could increase the pipeline repair rates (number of repairs per kilometer) by factors ranging from 1.3 to 2.0; being the higher the seismic intensity the lower the factor.

  19. Southern Perú coseismic subsidence: 23 June 2001 8.4-Mw earthquake

    Directory of Open Access Journals (Sweden)

    L. Ocola

    2008-01-01

    Full Text Available The 23-June-2001 8.4-Mw magnitude earthquake partially filled the 1868-seismic-gap in southern Perú. This earthquake produced a thrust faulting dislocation with a rupture that started at about ~200 km SE from the 1996's Nazca earthquake epicenter, and stopped near Ilo, at about 300 km from the epicenter, near a positive gravity anomaly offshore Ilo. The 23-June-2001-earthquake dislocation zone is under the Arequipa sedimentary Basin. Pre- and post-seismic GPS measurements at Camaná and Ilo at SIRGAS-GPS points (SIRGAS: Sistema de Referencia Geocéntrico para América del Sur and the average sea level pre- and post-seismic event at Mollendo tide gauge provide evidence of a regional subsidence of southern Perú, with 84 cm at Camaná, 16 cm at Ilo, and 15 cm at Mollendo. Field surveys post earthquake document significant subsidence in Camaná resort beaches. Results of a simple dislocation modelling of 23-June-2001 earthquake agree reasonably well with the observed data. However, the coseismic subsidence of southern Perú is at variance with the regional uplift of southern Perú based on Neotectonic studies. This fact, suggests that, in recent geological times, the magnitude of the secular uplift due to tectonic plate converge has been larger than the coseismic deformation recovery.

  20. Simulation of rock salt dissolution and its impact on land subsidence

    Directory of Open Access Journals (Sweden)

    A. Zidane

    2013-10-01

    Full Text Available Extensive land subsidence can occur due to subsurface dissolution of evaporites such as halite and gypsum. This paper explores techniques to simulate the salt dissolution forming an intrastratal karst, which is embedded in a sequence of carbonates, marls, anhydrite and gypsum. A numerical model is developed to simulate laminar flow in reactive fractures. The numerical model is based on the laminar steady state Stokes flow equation, and the advection dispersion transport equation coupled with the dissolution equation. The flow equation is solved using the nonconforming Crouzeix–Raviart (CR finite element approximation for the Stokes equation. For the transport equation, a combination between Discontinuous Galerkin Method and Multipoint Flux Approximation Method is proposed. The numerical effect of the dissolution is considered by using a dynamic mesh variation that increases the size of the mesh based on the amount of dissolved salt. The numerical method is applied to a 2-D geological cross section representing a Horst and Graben structure in the Tabular Jura of north-western Switzerland. It simulates salt dissolution within the geological section and predicts the amount of vertical dissolution as an indicator of subsidence that could occur. Simulation results showed that the highest dissolution amount is observed near the normal fault zones, and therefore the highest subsidence rates are expected above fault zones.

  1. Southern Perú coseismic subsidence: 23 June 2001 8.4-Mw earthquake

    Science.gov (United States)

    Ocola, L.

    2008-01-01

    The 23-June-2001 8.4-Mw magnitude earthquake partially filled the 1868-seismic-gap in southern Perú. This earthquake produced a thrust faulting dislocation with a rupture that started at about ~200 km SE from the 1996's Nazca earthquake epicenter, and stopped near Ilo, at about 300 km from the epicenter, near a positive gravity anomaly offshore Ilo. The 23-June-2001-earthquake dislocation zone is under the Arequipa sedimentary Basin. Pre- and post-seismic GPS measurements at Camaná and Ilo at SIRGAS-GPS points (SIRGAS: Sistema de Referencia Geocéntrico para América del Sur) and the average sea level pre- and post-seismic event at Mollendo tide gauge provide evidence of a regional subsidence of southern Perú, with 84 cm at Camaná, 16 cm at Ilo, and 15 cm at Mollendo. Field surveys post earthquake document significant subsidence in Camaná resort beaches. Results of a simple dislocation modelling of 23-June-2001 earthquake agree reasonably well with the observed data. However, the coseismic subsidence of southern Perú is at variance with the regional uplift of southern Perú based on Neotectonic studies. This fact, suggests that, in recent geological times, the magnitude of the secular uplift due to tectonic plate converge has been larger than the coseismic deformation recovery.

  2. Study of the Material Transfer Characteristics and Surface Morphology Due to Arc Erosion of PtIr Contact Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Saibei; XIE Ming; YANG Youcai; ZHANG Jiming; CHEN Yongtai; LIU Manmen; YANG Yunfeng; HU Jieqiong; CUI Hao

    2012-01-01

    By means of breaking tests on PtIr contact materials via a JF04C contact material testing machine,it was attempted to elucidate the characterstics of the various surface morphology and material transfer after the arc erosion process caused by break arc.The material transfer characteristics appeared in the experiments were concluded and analyzed.Meanwhile,the morphology of the anode and cathode surface were observed and analyzed by SEM.

  3. Abandoned deep mine subsidence investigation and remedial design, Interstate 70, Guernsey County, Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, A.G.; Clark, D.M.; Bechtel, T.D.

    1999-07-01

    A two thousand linear foot, undermined section of Interstate 70 in Guernsey County, Ohio experienced settlements due to pothole type subsidence events within the travel lanes, shoulders and adjacent right-of-way areas. Potholes measured approximately ten feet in depth and width. The subsidence occurred after the dewatering of the abandoned deep mine during auger mining operations west of the site. A two-phase emergency investigation was undertaken by the Ohio Department of Transportation (ODOT) and Gannett Fleming Cord dry and Carpenter (GF). The purpose of the investigation was to assess the immediate danger of potholes occurring in the traveled lanes and paved shoulders, to identify the subsidence mechanisms, and to design a remediation program. Phase one investigations involved the review of existing subsurface data, the advancement of shallow borings and the performance of multiple geophysical surveys including ground penetrating radar, seismic refraction and electromagnetic terrain conductivity. The Phase one investigations did not reveal the presence of subsidence voids. Phase two investigations included borings to the mine level and videotaping of mine conditions. The mine was found to be completely flooded. Based upon the collected data, two mechanisms of failure, localized roof fall and piping of overburden soils into the mine void, were identified. Two remedial alternatives, (1) the filling of the mine void, and (2) the reinforcement of the highway using geotextiles, were evaluated, Filling of the mined interval and grouting of overburden bedrock fractures and voids, within a limited area, were selected. Construction plans, specifications and cost estimates were prepared for bidding and award. During the bidding process, a catastrophic, pothole type failure of the I-70 travel lanes occurred. The interstate was closed and the planned remediation activities were performed as an emergency project. The mine interval was grouted and portions of the highway

  4. Land Subsidence in and around Bangkok area using ALOS/PALSAR data

    Science.gov (United States)

    Tanaka, A.; Mio, A.; Saito, Y.

    2012-12-01

    The metropolitan area of Bangkok, Thailand, has been subsided during the past decades. To effectively monitor, assess, and manage this ground deformation on various time scales and over broad areas, understanding these processes is of critical importance. This ground deformation has been monitored using leveling surveys since 1978 and InSAR (Interferometric Synthetic Aperture Radar) analysis. These results show that the Bangkok metropolitan city is subsiding with a rate of -20 mm/year in recent years, due to the law limiting groundwater pumping since the late 1980s, although in 1981 the highest subsidence rate up to 120 mm/year had been recorded in the eastern area [Phien-wej et al., 2006]. However, these studies were focused in the Bangkok metropolitan city using C-band satellites images. In this study, we applied the method of measuring long-term land subsidence by Differential InSAR and InSAR time series analysis using ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired between 2007 and 2010 to investigate ground deformation in and around Bangkok area. The ground deformation were detected both near the Chao Phraya river and the Tha Chin river, which is a distributary of the Chao Phraya river and flows westerly from the Chao Phraya through the central plains of Thailand until it mouths into the Gulf of Thailand. We compared our results with previous leveling and InSAR studies to find an overall consistency in the deformation estimates. The deformation rates have been monitored, with velocity a maximum rate of about -20 mm/year, and showed consistent with previous studies (e.g., Aobpaet et al., 2009). These results verify the validity of the method and data used.

  5. Heterogeneous rupture in the great Cascadia earthquake of 1700 inferred from coastal subsidence estimates

    Science.gov (United States)

    Wang, Pei-Ling; Engelhart, Simon E.; Wang, Kelin; Hawkes, Andrea D.; Horton, Benjamin P.; Nelson, Alan R.; Witter, Robert C.

    2013-01-01

    Past earthquake rupture models used to explain paleoseismic estimates of coastal subsidence during the great A.D. 1700 Cascadia earthquake have assumed a uniform slip distribution along the megathrust. Here we infer heterogeneous slip for the Cascadia margin in A.D. 1700 that is analogous to slip distributions during instrumentally recorded great subduction earthquakes worldwide. The assumption of uniform distribution in previous rupture models was due partly to the large uncertainties of then available paleoseismic data used to constrain the models. In this work, we use more precise estimates of subsidence in 1700 from detailed tidal microfossil studies. We develop a 3-D elastic dislocation model that allows the slip to vary both along strike and in the dip direction. Despite uncertainties in the updip and downdip slip extensions, the more precise subsidence estimates are best explained by a model with along-strike slip heterogeneity, with multiple patches of high-moment release separated by areas of low-moment release. For example, in A.D. 1700, there was very little slip near Alsea Bay, Oregon (~44.4°N), an area that coincides with a segment boundary previously suggested on the basis of gravity anomalies. A probable subducting seamount in this area may be responsible for impeding rupture during great earthquakes. Our results highlight the need for more precise, high-quality estimates of subsidence or uplift during prehistoric earthquakes from the coasts of southern British Columbia, northern Washington (north of 47°N), southernmost Oregon, and northern California (south of 43°N), where slip distributions of prehistoric earthquakes are poorly constrained.

  6. Direct measurements of the energy flux due to chemical reactions at the surface of a silicon sample interacting with a SF6 plasma

    CERN Document Server

    Dussart, Remi; Pichon, Laurianne E; Bedra, Larbi; Semmar, Nadjib; Lefaucheux, Philippe; Mathias, Jacky; Tessier, Yves; 10.1063/1.2995988

    2008-01-01

    Energy exchanges due to chemical reactions between a silicon surface and a SF6 plasma were directly measured using a heat flux microsensor (HFM). The energy flux evolution was compared with those obtained when only few reactions occur at the surface to show the part of chemical reactions. At 800 W, the measured energy flux due to chemical reactions is estimated at about 7 W.cm\\^{-2} against 0.4 W.cm\\^{-2} for ion bombardment and other contributions. Time evolution of the HFM signal is also studied. The molar enthalpy of the reaction giving SiF4 molecules was evaluated and is consistent with values given in literature.

  7. Extremely large non-saturating magnetoresistance and ultrahigh mobility due to topological surface states in metallic Bi2Te3 topological insulator

    OpenAIRE

    Shrestha, K; Chou, M; Graf, D.; Yang, H. D.; Lorenz, B.; Chu, C. W.

    2017-01-01

    Weak antilocalization (WAL) effects in Bi2Te3 single crystals have been investigated at high and low bulk charge carrier concentrations. At low charge carrier density the WAL curves scale with the normal component of the magnetic field, demonstrating the dominance of topological surface states in magnetoconductivity. At high charge carrier density the WAL curves scale with neither the applied field nor its normal component, implying a mixture of bulk and surface conduction. WAL due to topolog...

  8. Analyses of surface deformation with SBAR InSAR method and its relationship with aquifer occurrence in Surabaya City, East Java, Indonesia

    Science.gov (United States)

    Mochammad, Mushoddaq; Saepuloh, Asep

    2017-06-01

    Rapid development of Surabaya City requires space for industry and settlement. The city development is followed by increasing of water demand for various purposes. Large amount of groundwater extraction may cause ground subsidence. According to groundwater extraction, we tried to delineate the possibility of aquifer potential based on ground surface deformation using Interferometric Synthetic Aperture Radar (InSAR) and Electrical Resistivity methods. The InSAR is a method to estimate surface deformation in millimeter scale based on different phase of SAR data between acquisition times. In this paper, surface deformation combined with ground resistivity was used to analyse the potential of aquifer related to subsidence at Surabaya City, East Java, Indonesia. The Small Based Subset (SBAS) method was used to reduce phase delayed in the interferogram due to atmospheric condition. Based on the SBAS InSAR the deformation was detected at Surabaya City in January 2007 to February 2008. The largest and lowest deformation about 40 mm/year and about 0-10 mm/year were located in North to Southeastern and Western part of the city, respectively. The geodetic Global Positioning System (GPS) campaign in Surabaya confirmed that the detected deformation correlated with the ground subsidence with correlation coefficient about 0.96. To obtain the subsurface structures at subsidence zones, the Electrical Resistivity survey with Schlumberger configuration was performed in Surabaya city. According to the SBAS InSAR and subsurface resistivity, the subsidence around Pabeancantikan, Kenjeran, Simokerto and Tenggilismejoyo sub-districts agreed to high resistivity about 7-18 Ωm. The Sandstone of Kabuh and Pucangan formations in this area served as ground water aquifer which used by more than 200 wells. Ground water extraction probably triggered the subsidence at ground surface. The high resistivity at subsidence zones originated from high porosity of rocks served as aquifer with high

  9. Measurements of Land Subsidence Rates on the North-western Portion of the Nile Delta Using Radar Interferometry Techniques

    Science.gov (United States)

    Fugate, Joseph M.

    The Nile Delta is home to around 75 million people and most of Egypt's farmland and agricultural production. This area is currently threatened by Mediterranean Sea waters due to factors such as sediment starvation, climate change, and sea level fluctuations as well as subsidence. The low elevation and relief of the Nile Delta exposes many coastal communities, including the city of Alexandria, to potential inundation. This situation has become a concern for the area's residents but a better understanding of the processes occurring there can aid in deciding a suitable response. Recent studies have documented Holocene subsidence rates in the northeast part of the Nile Delta that average up to 8mm/year. In this study, PS-InSAR techniques are used to measure modern land subsidence rates on the north-central and north-western Nile Delta. Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques were applied to 23 ESA radar scenes from 2 orbital tracks spanning from 1992 to 2000 in the north-central and north-west portions of the Nile Delta. The area includes the cities of Alexandria, Greater Mahala, and Mansoura as well as the Rosetta promontory and lake Burullus, Idku Lagoon, and Maryut Lagoon. Results indicate that modern average-vertical ground motion velocities for the north-western and north-central Nile Delta range from emergent to subsidence of 8.5 mm/yr. The range of velocities measured are spatially varied in a complex way across the study area. Patterns of subsidence correlate closely to areas of most recent sediment deposition such as along coastlines and rivers, as well as in lagoons and lakes. Average subsidence velocities are also lower across the western sections of the Nile Delta than in the northeastern delta.

  10. Raising surface water levels in peat areas with dairy farming upscaling hydrological, agronomical and economic effects from farm-scale to local scale.

    NARCIS (Netherlands)

    Vos, de J.A.; Bakel, van P.J.T.; Hoving, I.E.; Smidt, R.A.

    2010-01-01

    Raising surface water levels in peat areas is a measure to reduce soil subsidence, to prevent decay of wooden foundations and to stimulate wet nature restoration and reduce greenhouse gas emissions. However, in these areas dairy farms are present and farming at wetter soils is difficult due to lower

  11. Subsidence and carbon loss in drained tropical peatlands

    Directory of Open Access Journals (Sweden)

    A. Hooijer

    2012-03-01

    Full Text Available Conversion of tropical peatlands to agriculture leads to a release of carbon from previously stable, long-term storage, resulting in land subsidence that can be a surrogate measure of CO2 emissions to the atmosphere. We present an analysis of recent large-scale subsidence monitoring studies in Acacia and oil palm plantations on peatland in SE Asia, and compare the findings with previous studies. Subsidence in the first 5 yr after drainage was found to be 142 cm, of which 75 cm occurred in the first year. After 5 yr, the subsidence rate in both plantation types, at average water table depths of 0.7 m, remained constant at around 5 cm yr−1. The results confirm that primary consolidation contributed substantially to total subsidence only in the first year after drainage, that secondary consolidation was negligible, and that the amount of compaction was also much reduced within 5 yr. Over 5 yr after drainage, 75 % of cumulative subsidence was caused by peat oxidation, and after 18 yr this was 92 %. The average rate of carbon loss over the first 5 yr was 178 t CO2eq ha−1 yr−1, which reduced to 73 t CO2eq ha−1 yr−1 over subsequent years, potentially resulting in an average loss of 100 t CO2eq ha−1 yr−1 over 25 yr. Part of the observed range in subsidence and carbon loss values is explained by differences in water table depth, but vegetation cover and other factors such as addition of fertilizers also influence peat oxidation. A relationship with groundwater table depth shows that subsidence and carbon loss are still considerable even at the highest water levels theoretically possible in plantations. This implies that improved plantation water management will reduce these impacts by 20 % at most, relative to current conditions, and that high rates of carbon loss and land subsidence are

  12. Preliminary results of land subsidence monitoring project in Konya Closed Basin between 2006–2009 by means of GNSS observations

    OpenAIRE

    2010-01-01

    One of the potential dangers that might arise as a result of bringing excessive amounts of groundwater to the surface of the Earth is land subsidence. Such surface deformations – these velocities may vary from a few millimetres to a few metres per year – do the greatest damage to infrastructure facilities and buildings in residential units. Agricultural lands, in which excessive irrigation is performed, and densely populated cities are more likely to suffer from land subs...

  13. What’s the Score? Walkable Environments and Subsidized Households

    Directory of Open Access Journals (Sweden)

    Young-Jae Kim

    2016-04-01

    Full Text Available Neighborhood walkability can influence individual health, social interactions, and environmental quality, but the relationships between subsidized households and their walkable environment have not been sufficiently examined in previous empirical studies. Focusing on two types of subsidized housing developments (Low-Income Housing Tax Credit (LIHTC and Public Housing (PH in Austin, Texas, this study evaluates the neighborhood walkability of place-based subsidized households, utilizing objectively measured Walk Score and walking-related built environment data. We also used U.S. Census block group data to account for the socio-demographic covariates. Based on various data, we employed bivariate and multivariate analyses to specify the relationships between subsidized households and their neighborhood walkable environment. The results of our bivariate analyses show that LIHTC households tend to be located in car-dependent neighborhoods and have more undesirable walking-related built environment conditions compared with non-LIHTC neighborhoods. Our regression results also represent that LIHTC households are more likely to be exposed to neighborhoods with low Walk Score, less sidewalk coverage, and more highways and major roads, while there are no significant associations for PH households. These findings imply that more attention and effort toward reducing the inequitable distributions of walkable neighborhood features supporting rather than hindering healthy lifestyles must be provided to subsidized households.

  14. Electromyographic Activities of Trunk Muscles Due to Different Exercise Intensities during Pulley-based Shoulder Exercises on an Unstable Surface.

    Science.gov (United States)

    Cha, Jae Yun; Shin, Doo Chul; Shin, Seung Ho; Lee, Myung Mo; Lee, Kyoung Jin; Song, Chang Ho

    2014-05-01

    [Purpose] This study examined the relationship between core stability and exercise intensity during a pulley-based shoulder exercise (PBSE) on an unstable support surface. [Subjects] Twenty healthy college students enrolled in this study. [Methods] Surface EMG was carried out in twenty healthy adult men. The electromyographic activities of the rectus abdominis (RA), erector spinae (ES), exercises with 14 kg or 26 kg of resistance and external oblique (EO) muscles during pulley-based shoulder on an unstable support surface (USS) were compared. [Results] The EMG signals of the RA, ES, and EO did not increase with increasing exercise resistance. [Conclusion] Increasing the exercise intensity to increase the core stability during PBSE on a USS may be ineffective.

  15. Free surface due to a flow driven by a rotating disk inside a vertical cylindrical tank: Axisymmetric configuration

    Science.gov (United States)

    Kahouadji, L.; Witkowski, L. Martin

    2014-07-01

    The flow driven by a rotating disk at the bottom of an open fixed cylindrical cavity is studied numerically and experimentally. The steady axisymmetric Navier-Stokes equations projected onto a curvilinear coordinate system are solved by a Newton-Raphson algorithm. The free surface shape is computed by an iterative process in order to satisfy a zero normal stress balance at the interface. In previous studies, regarding the free surface deflection, there is a significant disagreement between a first-order approximation [M. Piva and E. Meiburg, "Steady axisymmetric flow in an open cylindrical container with a partially rotating bottom wall," Phys. Fluids 17, 063603 (2005)] and a full numerical simulation [R. Bouffanais and D. Lo Jacono, "Unsteady transitional swirling flow in the presence of a moving free surface," Phys. Fluids 21, 064107 (2009)]. For a small deflection, the first-order approximation matches with our numerical simulation and for a large deflection a good agreement is found with experimental measurements.

  16. Faraday Rotation Due to Surface States in the Topological Insulator (Bi1-xSbx)2Te3.

    Science.gov (United States)

    Shao, Yinming; Post, Kirk W; Wu, Jhih-Sheng; Dai, Siyuan; Frenzel, Alex J; Richardella, Anthony R; Lee, Joon Sue; Samarth, Nitin; Fogler, Michael M; Balatsky, Alexander V; Kharzeev, Dmitri E; Basov, D N

    2017-02-08

    Using magneto-infrared spectroscopy, we have explored the charge dynamics of (Bi,Sb)2Te3 thin films on InP substrates. From the magneto-transmission data we extracted three distinct cyclotron resonance (CR) energies that are all apparent in the broad band Faraday rotation (FR) spectra. This comprehensive FR-CR data set has allowed us to isolate the response of the bulk states from the intrinsic surface states associated with both the top and bottom surfaces of the film. The FR data uncovered that electron- and hole-type Dirac Fermions reside on opposite surfaces of our films, which paves the way for observing many exotic quantum phenomena in topological insulators.

  17. Strengthened nonlinearity in liquid crystal panel with ZnSe aligning layers due to surface charge accumulation

    Science.gov (United States)

    Zhao, Hua; Xue, Tingyu; Fu, Jiayin; Zhang, Jingwen

    2015-09-01

    With ZnSe thin films as aligning layers in fabricating liquid crystal (LC) panel with pentylcyanobiphenyl doped with C60, the response time in writing holograms was shortened to milliseconds. When two laser beams were overlapped in an LC panel, 2D diffraction patterns were observed, along with exponential gain coefficient highly LC and ZnSe thickness dependent. In addition, energy transferring in subwavelength scale through surface grating was evident. By using a hybrid LC panel, it was found the energy transferring direction was voltage polarity and thickness dependent. Electrostatic modification based surface plasmon polariton excitation was proposed to explain all the findings

  18. Mardels, natural subsidence basins or abandoned quarries?

    Science.gov (United States)

    van Mourik, Jan; Slotboom, Ruud

    2015-04-01

    Coversands (chemical poor Late-glacial aeolian sand deposits) dominate the surface geology of an extensive area in northwestern Europe. Plaggic Anthrosols occur in cultural landscapes, developed on coversands. They are the characteristic soils that developed on ancient fertilized arable fields. Plaggic Anthrosols have a complex genesis. They are records of aspects environmental and agricultural history. In previous studies information of the soil records was unlocked by application of pollen analysis, 14C and OSL dating. In this study we applied biomarker analysis to unlock additional information about the applied organic sources in the production of plaggic manure. Radiocarbon dating suggested the start of sedentary agriculture (after a period, characterized by shifting cultivation and Celtic fields) between 3000 and 2000 BP. In previous studies is assumed that farmers applied organic sods, dug on forest soils and heath to produce organic stable manure to fertilize the fields. The mineral fraction of the sods was supposed to be responsible for the development of the plaggic horizon and the raise of the land surface. Optically stimulated Luminescence dating however suggested that plaggic deposition on the fields started relatively late, in the 18th century. The use of ectorganic matter from the forest soils must have been ended in the 10th-12th century, due to commercial forest clear cuttings as recorded in archived documents. These deforestations resulted in the first extension of sand drifting and famers had to protect the valuable heath against this 'environmental catastrophe'. The use of heath for sheep grazing and other purposes as honey production could continue till the 18th century, as recorded in archived documents. In the course of the 18th century, the population growth resulted in increasing demand for food. The deep stable economy was introduced and the booming demand for manure resulted in intensive sod digging on the heath. This caused heath

  19. Reduction of protein adsorption on silica and polystyrene surfaces due to coating with Complex Coacervate Core Micelles

    NARCIS (Netherlands)

    Brzozowska, A. M.; Hofs, B.; de Keizer, A.; Fokkink, R.; Stuart, Martien A. Cohen; Norde, W.

    2009-01-01

    The reduction of protein adsorption by a polymer brush formed upon adsorption of Complex Coacervate Core Micelles (C3Ms), consisting of a charged copolymer containing a neutral block and an oppositely charged homopolymer, on silica and polystyrene surfaces has been studied in situ using fixed angle

  20. Nonlinear Goos-Haenchen shifts due to surface polariton resonance in Kretschmann configuration with a Kerr-type substrate

    Energy Technology Data Exchange (ETDEWEB)

    Xu Guoding, E-mail: guodingxu@163.co [Department of Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Zang Taocheng; Mao Hongmin; Pan Tao [Department of Physics, Suzhou University of Science and Technology, Suzhou 215009 (China)

    2010-07-26

    As the surface polaritons are excited in Kretschmann configuration with a Kerr-type substrate, the nonlinear Goos-Haenchen (GH) shifts exhibit the optically hysteretic response to the intensity of incident light. For thicker metal films, the GH shifts become very sensitive to the intensity of incident light and the angle of incidence.

  1. Investigation and characterization of mining subsidence in Kaiyang Phosphorus Mine

    Institute of Scientific and Technical Information of China (English)

    DENG Jian; BIAN Li

    2007-01-01

    In Kaiyang Phosphorus Mine, serious environmental and safety problems are caused by large scale mining activities in the past 40 years. These problems include mining subsidence, low recovery ratio, too much dead ore in pillars, and pollution of phosphorus gypsum. Mining subsidence falls into four categories: curved ground and mesa, ground cracks and collapse hole, spalling and eboulement, slope slide and creeping. Measures to treat the mining subsidence were put forward: finding out and managing abandoned stopes, optimizing mining method (cut and fill mining method), selecting proper backfilling materials (phosphogypsum mixtures), avoiding disorder mining operation, and treating highway slopes. These investigations and engineering treatment methods are believed to be able to contribute to the safety extraction of ore and sustainable development in Kaiyang Phosphorus Mine.

  2. Study on neural network model for calculating subsidence factor

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-bing; ZHANG Jie

    2007-01-01

    The major factors influencing subsidence factor were comprehensively analyzed. Then the artificial neural network model for calculating subsidence factor was set up with the theory of artificial neural network (ANN). A large amount of data from observation stations in China was collected and used as learning and training samples to train and test the artificial neural network model. The calculated results of the ANN model and the observed values were compared and analyzed in this paper. The results demonstrate that many factors can be considered in this model and the result is more precise and closer to observed values to calculate the subsidence factor by the ANN model. It can satisfy the need of engineering.

  3. Ground Subsidence in the Beijing-Tianjin-Hebei Region from 1992 to 2014 Revealed by Multiple SAR Stacks

    Directory of Open Access Journals (Sweden)

    Yonghong Zhang

    2016-08-01

    Full Text Available The coordinated development of the Beijing-Tianjin-Hebei has become a national strategy with Beijing and Tianjin as twin engines driving the regional development. However, the Beijing-Tianjin-Hebei region has suffered dramatic ground subsidence during last two to three decades, mainly due to long-term groundwater withdrawal. Although, annual spirit leveling has been conducted routinely in some parts of Beijing and Tianjin, and InSAR technique has also been used to monitor ground subsidence in some local areas of the region, there is a lack of a complete survey of ground subsidence over the whole region. In this paper, we report a research on mapping ground subsidence in the Beijing-Tianjin-Hebei region over a long time span from 1992 to 2014. Three SAR datasets from four satellites are used: ERS-1/2 SAR images from 1992 to 2000, ENVISAT ASAR images from 2003 to 2010, and RADARSAT-2 images from 2012 to 2014. An improved multi-temporal InSAR method, namely “Multiple-master Coherent Target Small-Baseline InSAR” (MCTSB-InSAR, has been developed to process the datasets. A unique feature of MCTSB-InSAR is the adjustment process useful for wide area monitoring which provides an integrated solution for both calibration of InSAR-derived deformation and the harmonization of the deformation estimates from overlapping SAR frames. Three maps of the subsidence rate corresponding to the three periods over the wide Beijing-Tianjin-Hebei region are generated, with respective accuracy of 8.7 mm/year (1992–2000, 4.7 mm/year (2003–2010, and 5.4 mm/year (2012–2014 validated by more than 120 leveling measurements. The spatial-temporal characteristics of the development of ground subsidence in Beijing and Tianjin are analyzed. This research represents a first-ever effort on mapping ground subsidence over very large area and over long time span in China. The result is of significance to serve the decision-making on ground subsidence mitigation in the Beijing

  4. New experimental results on the interference of the states of the hydrogen atom due to long-range interaction with the metal surface

    NARCIS (Netherlands)

    Kucheryaev, YA; Pal'chikov, VG; Pchelin, YA; Sokolov, YL; Yakovlev, VP

    2005-01-01

    The interference of the 2P state of the hydrogen atom due to unknown long-range interaction with the metal surface (Sokolov effect) has been studied by an atomic interferometer. In contrast to previous experiments, where an atomic beam passed through slits in metal plates, a beam in the presented ex

  5. Volume changes of Vatnajökull ice cap, Iceland, due to surface mass balance, ice flow, and subglacial melting at geothermal areas

    DEFF Research Database (Denmark)

    Magnússon, Eyjólfur; Björnson, Helgi; Dall, Jørgen

    2005-01-01

    We present observed changes in the geometry of western Vatnajökull over a period of about ten years which are caused by the surface mass balance, ice flow (both during surges and quiescent periods), and basal melting due to geothermal and volcanic activity. Comparison of two digital elevation...

  6. Land Subsidence Caused by Groundwater Exploitation in Quetta Valley, Pakistan

    Directory of Open Access Journals (Sweden)

    Najeebullah Kakar

    2016-12-01

    Full Text Available Land subsidence is affecting several metropolitan cities in developing as well as developed countries around the world such as Nagoya (Japan, Shanghai (China, Venice (Italy and San Joaquin valley (United States. This phenomenon is attributed to natural as well as anthropogenic activities that include extensive groundwater withdrawals. Quetta is the largest city of Balochistan province in Pakistan. This valley is mostly dry and ground water is the major source for domestic and agricultural consumption. The unplanned use of ground water resources has led to the deterioration of water quality and quantity in the Quetta valley. Water shortage in the region was further aggravated by the drought during (1998-2004 that hit the area forcing people to migrate from rural to urban areas. Refugees from the war torn neighboring Afghanistan also contributed to rapid increase in population of Quetta valley that has increased from 0.26 million in 1975 to 3.0 million in 2016. The objective of this study was to measure the land subsidence in Quetta valley and identify the effects of groundwater withdrawals on land subsidence. To achieve this goal, data from five Global Positioning System (GPS stations were acquired and processed. Furthermore the groundwater decline data from 41 observation wells during 2010 to 2015 were calculated and compared with the land deformation. The results of this study revealed that the land of Quetta valley is subsiding from 30mm/y on the flanks to 120 mm/y in the central part. 1.5-5.0 m/y of groundwater level drop was recorded in the area where the rate of subsidence is highest. So the extensive groundwater withdrawals in Quetta valley is considered to be the driving force behind land subsidence.

  7. Experimental Study of the Subsidence Characteristics of Clayey Loess

    Institute of Scientific and Technical Information of China (English)

    Li Lan; Wang Lanmin

    2007-01-01

    Presented in this paper are the results of experimental study and analysis of the subsidence characteristics obtained from soil samples with different contents of clay particles though laboratory dynamic triaxial test, Laser particle size analysis, chemical analysis and electronic microscope scanning. By comparison of the obtained data, the following conclusions are drawn out: (1)The stability of the loess varies with different content of clay; (2) The relation between the dynamic shear strength and the clay particles is not monotonous, but parabolic; (3) In the same consolidation ratio, the clayey loess is the weakest subsidence-resistant when the clay particle content is between 16% ~ 17%.

  8. A study on subsidization of private schools in China

    OpenAIRE

    高, 暁楠

    2013-01-01

    The purpose of this Paper is to analyze the policies of subsidization of private schools in China, mainly base on the Law of the People’s Republic of China on Promotion of Privately-run Schools and the Regulations for the implementation of this standardization law, which have been promulgated recently. But for the particularity of private schools in China, the general view of the private schools in China, includes the concept of private school and the idea of subsidization of private schools,...

  9. Instabilities and bifurcations due to buoyancy in a cylindrical container heated from below with and without a free surface

    Science.gov (United States)

    El Gallaf, Anas; Touihri, Ridha; Henry, Daniel; Ben Hadid, Hamda

    2009-11-01

    Three-dimensional simulations of the buoyant convection in a cylindrical container heated from below are presented. Both the thresholds for the onset of the convection and the nonlinear evolution of this convection are calculated. The simulations concern two configurations: a cavity with a rigid upper surface (Rigid-Rigid case) and a cavity with a non-constrained free surface (Rigid-Free case). The results show a similar variation of the primary thresholds with the aspect ratio for the two configurations. In contrast, the nonlinear evolution of the convection is much changed between the two configurations. In particular, subcritical secondary branches with a very large subcriticity are obtained in the R-F case. To cite this article: A. El Gallaf et al., C. R. Mecanique 337 (2009).

  10. External magnetic field dependent shift of superparamagnetic blocking temperature due to core/surface disordered spin interactions

    Science.gov (United States)

    Lee, Kwan; Jang, Jung-tak; Nakano, Hiroshi; Nakagawa, Shigeki; Paek, Sun Ha; Bae, Seongtae

    2017-02-01

    Although the blocking temperature of superparamagnetic nanoparticles (SPNPs) is crucial for various spintronics and biomedical applications, the precise determination of the blocking temperature is still not clear. Here, we present ‘intrinsic’ and ‘extrinsic’ characteristics of the blocking temperature in SPNP systems. In zero-field-cooled/field-cooled (ZFC-FC) curves, there was no shift of ‘intrinsic blocking temperature’ at different applied external (excitation) magnetic fields. However, ‘extrinsic blocking temperature’ shift is clearly dependent on the external (excitation) magnetic field. According to our newly proposed physical model, the ‘intermediate spin layer’ located between the core and surface disordered spin layers is primarily responsible for the physical nature of the shift of extrinsic blocking temperature. Our new findings offer possibilities for characterizing the thermally induced physical properties of SPNPs. Furthermore, these findings provide a new empirical approach to indirectly estimate the qualitative degree of the disordered surface spin status in SPNPs.

  11. Investigations of surface characterization of silicone rubber due to tracking phenomena under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    Uma Maheswar Rao; S S M S Abdul Majeed; C Venkataseshaiah; R Sarathi

    2002-11-01

    In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies. The tracking time was different for a.c. and d.c. voltages.

  12. Temperature-dependent surface modification of Ta due to high-flux, low-energy He+ ion irradiation

    Science.gov (United States)

    Novakowski, T. J.; Tripathi, J. K.; Hassanein, A.

    2015-12-01

    This work examines the response of Tantalum (Ta) as a potential candidate for plasma-facing components (PFCs) in future nuclear fusion reactors. Tantalum samples were exposed to high-flux, low-energy He+ ion irradiation at different temperatures in the range of 823-1223 K. The samples were irradiated at normal incidence with 100 eV He+ ions at constant flux of 1.2 × 1021 ions m-2 s-1 to a total fluence of 4.3 × 1024 ions m-2. An additional Ta sample was also irradiated at 1023 K using a higher ion fluence of 1.7 × 1025 ions m-2 (at the same flux of 1.2 × 1021 ions m-2 s-1), to confirm the possibility of fuzz formation at higher fluence. This higher fluence was chosen to roughly correspond to the lower fluence threshold of fuzz formation in Tungsten (W). Surface morphology was characterized with a combination of field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). These results demonstrate that the main mode of surface damage is pinholes with an average size of ∼70 nm2 for all temperatures. However, significantly larger pinholes are observed at elevated temperatures (1123 and 1223 K) resulting from the agglomeration of smaller pinholes. Ex situ X-ray photoelectron spectroscopy (XPS) provides information about the oxidation characteristics of irradiated surfaces, showing minimal exfoliation of the irradiated Ta surface. Additionally, optical reflectivity measurements are performed to further characterize radiation damage on Ta samples, showing gradual reductions in the optical reflectivity as a function of temperature.

  13. Quantum critical point due to nested Fermi surface: damping of quasi-particles, resistivity and Hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Schlottmann, P. [Department of Physics, Florida State University, MC 4350-309 Keene Building, Tallahassee, FL 32306 (United States)]. E-mail: schlottm@martech.fsu.edu

    2004-12-31

    The nesting of the Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q and the interaction between electrons gives rise to spin- and charge-density waves. The order can gradually be suppressed by mismatching the nesting and a quantum critical point is obtained as the critical temperature tends to zero. We calculate the quasi-particle damping close to the quantum critical point and discuss its consequences on the resistivity and Hall effect.

  14. Nanostructures on GaAs surfaces due to 60 keV Ar{sup +}-ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Venugopal, V., E-mail: vinay.venu@gmail.com [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Division of Physics, School of Advanced Sciences, VIT University, Chennai Campus, Chennai 600 048 (India); Garg, Sandeep Kumar; Basu, Tanmoy [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Sinha, Om Prakash [Amity Institute of Nanotechnology, Amity University, Noida 201 303 (India); Kanjilal, D. [Inter-Univeristy Accelerator Center, Aruna Asaf Ali Marg, Delhi 110 067 (India); Bhattacharyya, S.R. [Saha Institute of Nuclear Physics, Kolkata 700 064 (India); Som, T. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)

    2012-02-15

    The effect of 60 keV Ar{sup +}-ion beam sputtering on the surface topography of p-type GaAs(1 0 0) was investigated by varying angle of incidence of the ion (060 Degree-Sign ) with respect to substrate normal and the ion fluence (2 Multiplication-Sign 10{sup 17}3 Multiplication-Sign 10{sup 18} ions/cm{sup 2}) at an ion flux of 3.75 Multiplication-Sign 10{sup 13} ions/cm{sup 2}-s. For normal incidence and at a fluence of 2 Multiplication-Sign 10{sup 17} ions/cm{sup 2}, holes and islands are observed with the former having an average size and density of 31 nm and 4.9 Multiplication-Sign 10{sup 9} holes/cm{sup 2}, respectively. For 30 Degree-Sign and 45 Degree-Sign off-normal incidence, in general, a smooth surface appears which is unaffected by increase of fluence. At 60 Degree-Sign off-normal incidence dots are observed while for the highest fluence of 3 Multiplication-Sign 10{sup 18} ions/cm{sup 2} early stage of ripple formation along with dots is observed with amplitude of 4 nm. The applicability and limitations of the existing theories of ion induced pattern formation to account for the observed surface topographies are discussed.

  15. Comparison of pulse height spectra on CsI(T1)/PIN photodiode radiation detector due to surface encapsulant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Soo; Ha, Jang Ho; Jeong, Man Hee; Kim, Young Soo; Kim, Dong Jin; Cho, Woo Jin; Choi, Hyo Jeong [Korea Atomic Energy Research Institute, Seoul (Korea, Republic of); Cho, Seung Yeon [Environmental Health Center, Yonsei University, Seoul (Korea, Republic of)

    2014-04-15

    Scintillation crystal converts the energy deposited by an X-ray or gamma ray to light. Usually this scintillation light is collected, converted to electrons and amplified by an photomultiplier tube (PMT). The PMT has the drawbacks of being bulky and requiring a high voltage (HV) to operate it. This scinitllation light can also be collected in a solid state photo-detector, such as a silicon PIN photodiode and an avanlanche photodiode. PIN photodiode, which have 10 mm X 10 mm{sup 2} active area, were fabricated with anti-reflective coating and match with CsI(Tl) scintillator. In this study, radiation reasonabilities were compared with and without surface encapsulant epoxy. Silicon PIN Photodiodes were fabricated with AR coating. To match with CsI(Tl) scintillator, surface encapsulant was applied on the PIN photodiodes. Leakage currents for all the PIN photodiodes show several nA up to 100 V. The pulse height spectra and comparison of the CsI(Tl)PIN photodiode in case of surface encapsulation on PIN photodiode will be presented at the conference.

  16. Error in Radar-Derived Soil Moisture due to Roughness Parameterization: An Analysis Based on Synthetical Surface Profiles

    Directory of Open Access Journals (Sweden)

    Bernard De Baets

    2009-02-01

    Full Text Available In the past decades, many studies on soil moisture retrieval from SAR demonstrated a poor correlation between the top layer soil moisture content and observed backscatter coefficients, which mainly has been attributed to difficulties involved in the parameterization of surface roughness. The present paper describes a theoretical study, performed on synthetical surface profiles, which investigates how errors on roughness parameters are introduced by standard measurement techniques, and how they will propagate through the commonly used Integral Equation Model (IEM into a corresponding soil moisture retrieval error for some of the currently most used SAR configurations. Key aspects influencing the error on the roughness parameterization and consequently on soil moisture retrieval are: the length of the surface profile, the number of profile measurements, the horizontal and vertical accuracy of profile measurements and the removal of trends along profiles. Moreover, it is found that soil moisture retrieval with C-band configuration generally is less sensitive to inaccuracies in roughness parameterization than retrieval with L-band configuration.

  17. Charged plate in asymmetric electrolytes: One-loop renormalization of surface charge density and Debye length due to ionic correlations

    Science.gov (United States)

    Ding, Mingnan; Lu, Bing-Sui; Xing, Xiangjun

    2016-10-01

    Self-consistent field theory (SCFT) is used to study the mean potential near a charged plate inside a m :-n electrolyte. A perturbation series is developed in terms of g =4 π κ b , where b a n d 1 /κ are Bjerrum length and bare Debye length, respectively. To the zeroth order, we obtain the nonlinear Poisson-Boltzmann theory. For asymmetric electrolytes (m ≠n ), the first order (one-loop) correction to mean potential contains a secular term, which indicates the breakdown of the regular perturbation method. Using a renormalizaton group transformation, we remove the secular term and obtain a globally well-behaved one-loop approximation with a renormalized Debye length and a renormalized surface charge density. Furthermore, we find that if the counterions are multivalent, the surface charge density is renormalized substantially downwards and may undergo a change of sign, if the bare surface charge density is sufficiently large. Our results agrees with large MC simulation even when the density of electrolytes is relatively high.

  18. Land subsidence in the Yangtze River Delta, China revealed from multi-frequency SAR Interferometry

    Science.gov (United States)

    Li, Zhenhong; Motagh, Mahdi; Yu, Jun; Gong, Xulong; Wu, Jianqiang; Zhu, Yefei; Chen, Huogen; Zhang, Dengming; Xu, Yulin

    2014-05-01

    Land subsidence is a major worldwide hazard, and its principal causes are subsurface fluid withdrawal, drainage of organic soils, sinkholes, underground mining, hydrocompaction, thawing permafrost, and natural consolidation. Land subsidence causes many problems including: damage to public facilities such as bridges, roads, railroads, electric power lines, underground pipes; damage to private and public buildings; and in some cases of low-lying land, can increase the risk of coastal flooding from storm surges and rising sea-levels. In China, approximately 48600 km2 of land, an area roughly 30 times of the size of the Greater London, has subsided (nearly 50 cities across 16 provinces), and the annual direct economic loss is estimated to be more than RMB 100 million (~12 million). It is believed that the Suzhou-Wuxi-Changzhou region within the Yangtze River Delta is the most severely affected area for subsidence hazards in China. With its global coverage and all-weather imaging capability, Interferometric SAR (InSAR) is revolutionizing our ability to image the Earth's surface and the evolution of its shape over time. In this paper, an advanced InSAR time series technique, InSAR TS + AEM, has been employed to analysed ERS (C-band), Envisat (C-band) and TerraSAR-X (X-band) data collected over the Suzhou-Wuxi-Changzhou region during the period from 1992 to 2013. Validation with precise levelling and GPS data suggest: (1) the accuracy of the InSAR-derived mean velocity measurements is 1-3 mm/yr; (2) InSAR-derived displacements agreed with precise levelling with root mean square errors around 5 mm. It is evident that InSAR TS + AEM can be used to image the evolution of deformation patterns in the Suzhou-Wuxi-Changzhou region over time: the maximum mean velocity decreased from ~12 cm/yr during the period of 1992-1993 to ~2 cm/yr in 2003-2013. This is believed to be a result of the prohibition of groundwater use carried out by Jiangsu provincial government. The combination

  19. Land subsidence and caprock dolines caused by subsurface gypsum dissolution and the effect of subsidence on the fluvial system in the Upper Tigris Basin (between Bismil Batman, Turkey)

    Science.gov (United States)

    Doğan, Uğur

    2005-11-01

    Karstification-based land subsidence was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land subsidence, where there are secondary and tertiary subsidence developments, reaches 140 km 2. Subsidence depth ranges between 40 and 70 m. The subsidence was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a subsidence with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of subsidence and formation of caprock dolines on loosely textured Upper Miocene-Pliocene cover formations. The Tigris River runs through the subsidence area between Batman and Bismil. There are four terrace levels as T1 (40 m), T2 (30 m), T3 (10 m) and T4 (4-5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by subsidence. The subsidence developed gradually throughout the Quaternary; however no terrace was formed purely because of subsidence.

  20. Changes in Temperature and Fate of Soil Organic Matter in an Andisol due to Soil Surface Burning

    Science.gov (United States)

    Obuchi, Atsuko; Nishimura, Taku; Mizoguchi, Masaru; Imoto, Hiromi; Miyazaki, Tsuyoshi

    This is a print of a camera-ready Japanese manuscript for the Transactions of JSIDRE. This will provide an example and directions for the layout and font size/style to be used. Please refer to this when preparing the headings, figures/table and text of your manuscript. The manuscript should be submitted on A4 size. Changes in temperature, soil moisture, and carbon and nitrogen contents were measured in Andisol under soil surface burning. Soil samples were packed into an unglazed cylinder of 15 cm inner diameter and 30 cm high. Charcoal was burned for 6 hours on the surface of the soil column. During the burning soil surface temperature rose to between 600-700°C. In initially wet soil, rise in soil temperature was retarded for a while at around 95-100°C. On the other hand, in initially dry Toyoura sand showed more rapid temperature increase without retardation. The temperature retardation in the wet soil could be caused by consumption of latent heat by vaporization of soil water. Rate of proceeding of the 100°C front was proportional to square root of the burning time. This indicates that higher the initial volumetric water content, shallower the depth affected by burning. Soil samples suffered temperature above 500°C still had total carbon and nitrogen contents of over 20 and 1 g kg-1, respectively, whereas the soil that was heated up to over 500°C by muffle furnace contained less than 0.4 and 0.1 g kg-1 of the carbon and nitrogen.

  1. Thermophoresis and Brownian effects on the Blasius flow of a nanofluid due to a curved surface with thermal radiation

    Science.gov (United States)

    Naveed, M.; Abbas, Z.; Sajid, M.

    2016-06-01

    In this analysis, we have discussed the Blasius flow of a nanofluid over a curved surface coiled in a circle of radius R . The physical situation is formulated in a mathematical model using a curvilinear coordinates system. The model is considered for the nanofluid including the effects of Brownian motion and thermophoresis in the presence of thermal radiation. A similarity solution of the developed ordinary differential equations is obtained numerically using the shooting method. The influence of the various involved parameters on the flow phenomena are analyzed through graphs and tables.

  2. Craters in concrete slabs due to detonation – drawbacks of material models with a Mohr-Coulomb yield surface

    Directory of Open Access Journals (Sweden)

    Conrad Markus

    2015-01-01

    Full Text Available Numerical simulations have been performed with a commercial distributed explicit FE-solver and the results have been compared with experiments. High explosive was placed in front of different concrete slabs with the dimension 100 × 100 × 16 cm. Some of the results of the simulations, in particular the profile of the craters, are not in agreement with the test results. Therefore the key characteristics of the constitutive equation based on Mohr-Coulomb yield surfaces and a damage evolution linked to the plastic strain has been reviewed.

  3. HerMES: A DEFICIT IN THE SURFACE BRIGHTNESS OF THE COSMIC INFRARED BACKGROUND DUE TO GALAXY CLUSTER GRAVITATIONAL LENSING

    Energy Technology Data Exchange (ETDEWEB)

    Zemcov, M.; Cooray, A.; Bock, J.; Dowell, C. D.; Nguyen, H. T. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Blain, A. [Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Bethermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A.; Glenn, J. [Center for Astrophysics and Space Astronomy 389-UCB, University of Colorado, Boulder, CO 80309 (United States); Conversi, L. [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, E-28691 Madrid (Spain); Farrah, D.; Oliver, S. J.; Roseboom, I. G. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Griffin, M. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Halpern, M.; Marsden, G. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Jullo, E.; Kneib, J.-P. [Aix-Marseille Universite, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR7326, F-13388 Marseille (France); Richard, J., E-mail: zemcov@caltech.edu [Centre de Recherche Astronomique de Lyon, Universite Lyon 1, 9 avenue Charles Andre, F-69230 Saint-Genis Laval (France); and others

    2013-06-01

    We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after removing detected sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitude of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I{sub 250{mu}m}>0.69{sub -0.03}{sup +0.03}(stat.){sub -0.06}{sup +0.11}(sys.) MJy sr{sup -1}, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe this effect in existing high angular resolution data at other wavelengths where the CIB is bright, which would allow tests of models of the faint source component of the CIB.

  4. HerMES: A Deficit in the Surface Brightness of the Cosmic Infrared Background Due to Galaxy Cluster Gravitational Lensing

    CERN Document Server

    Zemcov, M; Cooray, A; Bethermin, M; Bock, J; Clements, D L; Conley, A; Conversi, L; Dowell, C D; Farrah, D; Glenn, J; Griffin, M; Halpern, M; Jullo, E; Kneib, J -P; Marsden, G; Nguyen, H T; Richard, S J Oliver J; Roseboom, I G; Schulz, B; Scott, Douglas; Shupe, D L; Smith, A J; Valtchanov, I; Viero, M; Wang, L; Wardlow, J

    2013-01-01

    We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after subtracting sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitude of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I(250 microns) > 0.69_(-0.03)^(+0.03) (stat.)_(-0.06)^(+0.11) (sys.) MJy/sr, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe th...

  5. In situ surface-enhanced Raman spectroscopy effect in zeolite due to Ag2Se quantum dots

    Science.gov (United States)

    Martinez-Nuñez, C. E.; Cortez-Valadez, M.; Delgado-Beleño, Y.; Flores-López, N. S.; Román-Zamorano, J. F.; Flores-Valenzuela, J.; Flores-Acosta, M.

    2017-02-01

    This study shows the presence of surface-enhanced Raman spectroscopy (SERS) effect caused by Ag2Se quantum dots embedded in the zeolite matrix. The quantum dots that were synthesised and stabilised in the matrix of F9-NaX zeolite show a size of 5 nm and a quasi-spherical morphology. The calculated interplanar distances confirm the presence of quantum dots in cubic phase Im-m. We suppose that the in situ SERS effect in the material is caused by chemical-enhancement mechanism (CEM). The density functional theory (DFT) is undertaken to corroborate our hypothesis. The structure H8Si8Al8O12 represents the zeolite cavity unit, and small clusters of (Ag2Se) n represent the quantum dots. Both structures interact in the cavity to obtain the local minimum of the potential energy surface, leading to new molecular orbitals. After the analysis of the predicted Raman spectrum, the Raman bands increase significantly, agreeing with the experimental results at low wavenumbers in F9-NaX zeolite.

  6. Laser-induced damage characteristics in fused silica surface due to mechanical and chemical defects during manufacturing processes

    Science.gov (United States)

    Li, Yaguo; Yuan, Zhigang; Wang, Jian; Xu, Qiao

    2017-06-01

    Mechanical and chemical defects incurred by grinding and polishing as well as post-processing have been recognized as the most influential culprits that hamper the elevation of laser power/energy in high peak power/energy laser systems. In order to find out the causes for limiting the operational power of laser systems, the effects of these defects on laser damage and removal and mitigation of the defects were investigated in detail in the article. Cracks and scratches were created, annealed, etched and damaged so as to reveal the likely effects of mechanical defects on damage and potential techniques to reduce their influence. The results show that HF-based etching can open and smooth cracks/scratches, improving laser-induced damage threshold (LIDT) at scratches by up to >250%. Thermal annealing did heal, to some extent, cracks but the LIDT is little improved. Both HF-etching and leaching proves to be effective in removing metallic contamination during polishing process and handling of optics, which can "contribute" to damage/damage density in fused silica. However, HF-based etching may degrade surface roughness, from 20 nm under some conditions when >20 μm material was etched away while the surface roughness was perceptibly altered by leaching (30 J/cm2 (355 nm @3 ns, beam diameter 400 μm @1/e2), a significant progress.

  7. Subsidence monitoring in coal area using time-series InSAR combining persistent scatterers and distributed scatterers

    Science.gov (United States)

    Zhang, Zhengjia; Wang, Chao; Tang, Yixian; Fu, Qiaoyan; Zhang, Hong

    2015-07-01

    In coal mining areas, ground subsidence persistently happens, which produces serious environmental issues and affects the development of cities. To monitor the ground deformation due to coal mining, a modified time-series InSAR technique combining persistent scatterers (PSs) and distributed scatterers (DSs) is presented in this paper. In particular, DSs are efficiently identified using classified information and statistical characteristics. Furthermore, a two-scale network is introduced into traditional PSI to deal with PSs and DSs in a multi-layer framework by taking the advantage of the robust of PSs and the widely distribution of DSs. The proposed method is performed to investigate the subsidence of Huainan City, Anhui province (China), during 2012-2013 using 14 scenes of Radarsat-2 images. Experimental results show that the proposed method can ease the estimation complexity and significantly increase the spatial density of measurement points, which can provide more detailed deformation information. Result shows that there are obvious subsidence areas detected in the test site with subsidence velocity larger than 5 cm/year. The proposed method brings practical applications for non-urban area deformation monitoring.

  8. At Whose Service? Subsidizing Services and the Skill Premium

    NARCIS (Netherlands)

    van Groezen, B.J.A.M.; Meijdam, A.C.

    2010-01-01

    In this paper we investigate the effects of subsidizing low-skilled, labourintensive services hired by high-skilled individuals in the presence of labour income taxation. Whether such a subsidy can be Paretoimproving depends crucially on the degree of substitutability of both types of labour in the

  9. Subsidence of residual soils in a karst terrain

    Energy Technology Data Exchange (ETDEWEB)

    Drumm, E.C.; Kane, W.F.; Ben-Hassine, J.; Scarborough, J.A. (Tennessee Univ., Knoxville, TN (USA)); Ketelle, R.H. (Oak Ridge National Lab., TN (USA))

    1990-06-01

    Siting and operating landfills for solid waste disposal in eastern Tennessee that can operate with minimum impact on groundwater is problematic. The operational requirement of thick, excavational soils and the regulatory requirement of a buffer between disposal units and an aquifer result in siting most operating East Tennessee landfills in outcrop areas of the Knox Group. However, the common occurrence of karst terrain and sinkholes in the Knox Group indicates the vulnerability of such sites to rapid groundwater recharge and flow and the potential for subsidence or collapse of soil into bedrock cavities. To address the potential for subsidence or collapse of soils at the East Chestnut Ridge site on the Department of Energy's (DOE) Oak Ridge Reservation (ORR), the following activities and analyses were completed: The locations of karst features on the site were determined by field reconnaissance; several sinkholes were selected for detailed examination; soil boring, sampling, and physical testing were performed in soils located within, adjacent to, and outside of sinkholes to characterize soil strength at various depths; detailed plane surveys were made for 11 sinkholes to measure accurately their dimension and shape for use in determining profile functions for subsidence basins at the site; The stress-deformation response of a typical soil profile overlying a hypothetical bedrock cavity was analyzed numerically for a range of soil thickness and a range of cavity radii. A consistent estimate of the relationship between subsidence basin dimension, soil thickness, and cavity radius has been derived. 30 refs., 41 figs., 7 tabs.

  10. IMPACT OF OIL ON THE MECHANICAL PROPERTIES OF SOIL SUBSIDENCE

    Directory of Open Access Journals (Sweden)

    Алексей Алексеевич Бурцев

    2016-08-01

    Full Text Available The paper studied the effect of oil content on the mechanical properties of soil subsidence - Ek modulus and compressibility factor m0, obtained in the laboratory with the help of artificial impregnation oil soil samples. A comparison of the above parameters with samples of the same soil in the natural and water-saturated conditions has been perfomed.

  11. Tectonics and subsidence evolution of the Sirt Basin, Libya

    NARCIS (Netherlands)

    Abadi, A.M.; Wees, J.D. van; Dijk, P.M. van; Cloetingh, S.A.P.L.

    2005-01-01

    Backstripping analysis of 225 wells located within the Sirt Basin (Fig. 1) provide new constraints on the Sirt Basin development. Four coherent tectonic phases from Late Jurassic to present. The presentation of contour maps of subsidence and crustal stretching allows to visualize spatial and tempora

  12. How large-scale subsidence affects stratocumulus transitions (discussion paper)

    NARCIS (Netherlands)

    Van der Dussen, J.J.; De Roode, S.R.; Siebesma, A.P.

    2015-01-01

    Some climate modeling results suggest that the Hadley circulation might weaken in a future climate, causing a subsequent reduction in the large-scale subsidence velocity in the subtropics. In this study we analyze the cloud liquid water path (LWP) budget from large-eddy simulation (LES) results of

  13. Subsidized Housing, Public Housing, and Adolescent Violence and Substance Use

    Science.gov (United States)

    Leech, Tamara G. J.

    2012-01-01

    This study examines the separate relationships of public housing residence and subsidized housing residence to adolescent health risk behavior. Data include 2,530 adolescents aged 14 to 19 who were children of the National the Longitudinal Study of Youth. The author used stratified propensity methods to compare the behaviors of each…

  14. The Opportunity Illusion: Subsidized Housing and Failing Schools in California

    Science.gov (United States)

    Pfeiffer, Deirdre

    2009-01-01

    Since the late 1980s, the Low-Income Housing Tax Credit (LIHTC) program has funded the bulk of subsidized development nationwide, enabling the construction of over 100,000 units targeted to lower income households in California alone (California Tax Credit Allocation Committee 2009c). Yet, by not encouraging the siting of projects in racially…

  15. Collaboration and Subsidized Early Care and Education Programs in Illinois

    Science.gov (United States)

    Spielberger, Julie; Zanoni, Wladimir; Barisik, Elizabeth

    2013-01-01

    As a result of policy changes following welfare reform in 1996 and the costs associated with providing high-quality early care and education for children of low-income working families, agency collaboration in the state of Illinois has become an increasingly salient feature of subsidized early care and education programs (SECE). The authors…

  16. Challenges related to flotation cleaning of oil shales. Issues due to compositional and surface features and post-grinding surface behavior

    OpenAIRE

    Altun N. Emre

    2016-01-01

    Oil shale is an important energy resource alternative. Despite its recognition as an unconventional oil source, oil shale is also considered as an important solid fossil fuel alternative to coal and lignites due to the solid form and remarkable extent of organic content. Utilization possibilites, similar to coal and lignites, have been considered in the past decades and direct use of oil shales in thermal power production has been possible in countries like Estonia and China. In the perspecti...

  17. Protein overexport in a Saccharomyces cerevisiae mutant is not due to facilitated release of cell-surface proteins.

    Science.gov (United States)

    Alexieva, K I; Venkov, P V

    2000-01-01

    Saccharomyces cerevisiae strain MW11 is a temperature-sensitive mutant which exports twenty times more proteins at 37 degrees C than parental or wild-type strains do. To understand the mechanism underlying the protein overexport in the mutant the possibility of an altered cell-wall structure leading to facilitated release of cell-surface proteins was studied. Data on calcofluor white and zymolyase sensitivities, resistance to killer 1 toxin and determination of exported acid phosphatase and invertase did not provide evidence for alterations in the cell-wall structure that could explain the protein overexport phenotype. The results were obtained in experiments when transcription of mutated gene was discontinued which permits the full expression of the protein overexport phenotype.

  18. Salt Marsh Response and Recovery to Coseismic Subsidence

    Science.gov (United States)

    Aranda, A. N.; Carlin, J. A.; Rhodes, B. P.; Kirby, M.; Leeper, R. J.; Smith, R. W.

    2016-12-01

    Salt marshes worldwide are under increasing stress from eustatic sea level rise. Along the tectonically active west coast of North America, some salt marshes are also vulnerable to abrupt increases in relative sea level rise (RSLR) resulting from coseismic subsidence. Elevation zonation of sub-environments within a marsh provides the opportunity to interpret the sedimentary record in marshes to infer past earthquakes, which may improve understanding of regional seismic hazards and ecosystem response to increases in sea level. Our study area is the Seal Beach Wetlands (SBW), an 3 km2 salt marsh straddling the seismically active Newport-Inglewood fault zone in southern California. A previous study of the SBW identified sedimentary evidence of three coseismic subsidence events. Here, our goals were to identify coseismic subsidence events preserved in SBW stratigraphy and to quantify marsh recovery following an earthquake to assess marsh resiliency to rapid RSLR. To do this, we focused on one core collected near the fringe of the SBW and applied a suite of sedimentary and geochemical analyses. Our results indicated that the SBW may preserve sedimentary evidence of four potential coseismic subsidence events. Events were distinguished in the stratigraphy by a sharp upper contact interpreted as an abrupt shift in marsh depositional sub-environments, from a vegetated marsh, to an intertidal mudflat or a subtidal environment. This stratigraphy suggests that the marsh rapidly subsided, preserving the evidence of the vegetated marsh as a peat deposit overlain by a low-organic mud or muddy-sand layer. A typical marsh accretion facies succession occurred above each earthquake event in the core, suggesting full marsh recovery. From the core data, we also observed that the net average rate of marsh recovery, i.e., marsh accretion, was consistent. Estimated recovery rates between 0.6 and 1.1 mm/yr were comparable to the overall accretion rate and regional late Holocene RSLR rate

  19. Spherical MoS{sub 2} micro particles and their surface dispersion due to addition of cobalt promoters

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, M. A.; Flores, S.; Farias M, J. R. [Universidad Autonoma de Ciudad Juarez, Instituto de Ingenieria y Tecnologia, Av. del Charro No. 610, 32310 Ciudad Juarez, Chihuahua (Mexico); Correa, V. [Metropolitan University, Chemistry Department, San Juan (Puerto Rico); Torres, B.; Chianelli, R. R., E-mail: manuel.ramos@uacj.m [Materials Research and Technology Institute, 500 W. University Av. Burges Hall No. 303, El Paso 79902, Texas (United States)

    2011-07-01

    We present here a hydrothermal synthesis on spherical shape molybdenum di-sulfide (MoS{sub 2}) micro particles using thio molybdate salts and sodium silicate as reducing agent. To understand the role of cobalt promoters on this particular MoS{sub 2} spherical shape a second reaction was carried out using same precursors plus addition of Co following same pressure and temperature conditions. Both products (before and after Co promoter) were characterized using scanning electron and transmission electron microscopy analysis. From Sem measurements a spherical average size diameter of {approx} 2.855 {mu}m on pure MoS{sub 2} is observed and disperse surface once cobalt is incorporated into the reaction. From Tem observation and interlayer average distance of {approx} 0.63 nm is obtained for MoS{sub 2}-MoS{sub 2} slabs on samples with Co content. X-ray diffraction indicated principal crystallographic planes to be (002), (100), (101), (102), (103), (006), (105), and (110) for both MoS{sub 2} and MoS{sub 2}/Co samples. (Author)

  20. Zonal surface wind jets across the Red Sea due to mountain gap forcing along both sides of the Red Sea

    KAUST Repository

    Jiang, Houshuo

    2009-01-01

    [1] Mesoscale atmospheric modeling over the Red Sea, validated by in-situ meteorological buoy data, identifies two types of coastal mountain gap wind jets that frequently blow across the longitudinal axis of the Red Sea: (1) an eastward-blowing summer daily wind jet originating from the Tokar Gap on the Sudanese Red Sea coast, and (2) wintertime westward-blowing wind-jet bands along the northwestern Saudi Arabian coast, which occur every 10-20 days and can last for several days when occurring. Both wind jets can attain wind speeds over 15 m s-1 and contribute significantly to monthly mean surface wind stress, especially in the cross-axis components, which could be of importance to ocean eddy formation in the Red Sea. The wintertime wind jets can cause significant evaporation and ocean heat loss along the northeastern Red Sea coast and may potentially drive deep convection in that region. An initial characterization of these wind jets is presented. Copyright 2009 by the American Geophysical Union.

  1. Near-surface seismic velocity changes in a salt-dominated environment due to shaking and thermal stressing

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-05-01

    We report on results from a seismic station of the Integrated Plate Boundary Observatory Chile (IPOC) showing a superior sensitivity of seismic velocity changes in the surrounding medium to shaking and temperature. 5 years of daily autocorrelations of the IPOC network are analyzed with passive image interferometry. Due to the particular geological conditions we observe a high sensitivity of the medium around the station near Patache (PATCX) resulting in annual periodic velocity variations and temporary velocity reductions induced by ground shaking. We observe a linear relationship between the amplitude of the velocity reductions and the peak ground acceleration (PGA) of nearby earthquakes at station PATCX. Although velocity reductions are also observed at other stations of the IPOC array for the Mw 7.7 Tocopilla earthquake a clear relationship between the PGA of this earthquake and the induced velocity reductions at the different stations is not visible. Furthermore, we observe velocity variations with an annual and daily period. We present different arguments that these periodic changes are caused by variations of the atmospheric temperature. In this context we construct a model that starts at observed temperature variations and evaluates thermal stresses induced by the temperature gradients. Using radiative transfer based sensitivity kernels and third order elastic constants we relate the distribution of thermal stress in the subsurface to observable time shifts of coda waves. The model is able to reproduce the major features confirming that stress changes in the subsurface can be detected with noise based monitoring.

  2. Volume changes of Vatnajökull ice cap, Iceland, due to surface mass balance, ice flow, and subglacial melting at geothermal areas

    DEFF Research Database (Denmark)

    Magnússon, Eyjólfur; Björnson, Helgi; Dall, Jørgen

    2005-01-01

    We present observed changes in the geometry of western Vatnajökull over a period of about ten years which are caused by the surface mass balance, ice flow (both during surges and quiescent periods), and basal melting due to geothermal and volcanic activity. Comparison of two digital elevation...... models shows that from 1985 to 1998 the outlet glaciers have lost 14 ± 5 km3, on the average 1 m/yr...

  3. Impacts of 25 years of groundwater extraction on subsidence in the Mekong delta, Vietnam

    Science.gov (United States)

    Many major river deltas in the world are subsiding and consequently become increasingly vulnerable to flooding and storm surges, salinization and permanent inundation. For the Mekong Delta, annual subsidence rates up to several centimetres have been reported. Excessive groundwate...

  4. Impact of fire on global land surface air temperature and energy budget for the 20th century due to changes within ecosystems

    Science.gov (United States)

    Li, Fang; Lawrence, David M.; Bond-Lamberty, Ben

    2017-04-01

    Fire is a global phenomenon and tightly interacts with the biosphere and climate. This study provides the first quantitative assessment and understanding of fire’s influence on the global annual land surface air temperature and energy budget through its impact on terrestrial ecosystems. Fire impacts are quantified by comparing fire-on and fire-off simulations with the Community Earth System Model (CESM). Results show that, for the 20th century average, fire-induced changes in terrestrial ecosystems significantly increase global land annual mean surface air temperature by 0.18 °C, decrease surface net radiation and latent heat flux by 1.08 W m-2 and 0.99 W m-2, respectively, and have limited influence on sensible heat flux (-0.11 W m-2) and ground heat flux (+0.02 W m-2). Fire impacts are most clearly seen in the tropical savannas. Our analyses suggest that fire increases surface air temperature predominantly by reducing latent heat flux, mainly due to fire-induced damage to the vegetation canopy, and decreases net radiation primarily because fire-induced surface warming significantly increases upward surface longwave radiation. This study provides an integrated estimate of fire and induced changes in ecosystems, climate, and energy budget at a global scale, and emphasizes the importance of a consistent and integrated understanding of fire effects.

  5. A spectral formalism for computing three-dimensional deformations due to surface loads. 2: Present-day glacial isostatic adjustment

    Science.gov (United States)

    Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.

    1994-01-01

    Using a spherically symmetric, self-gravitating, linear viscoelastic Earth model, we predict present-day three-dimensional surface deformation rates and baseline evolutions arising as a consequence of the late Pleistocene glacial cycles. In general, we use realistic models for the space-time geometry of the final late Pleistocene deglaciation event and incorporate a gravitationally self-consistent ocean meltwater redistribution. The predictions of horizontal velocity presented differ significantly, in both their amplitude and their spatial variation, from those presented in earlier analysis of others which adopted simplified models of both the late Pleistocene ice history and the Earth rheology. An important characteristic of our predicted velocity fields is that the melting of the Laurentide ice sheet over Canada is capable of contributing appreciably to the adjustment in Europe. The sensitivity of the predictions to variations in mantle rheology is investigated by considering a number of different Earth models, and by computing appropriate Frechet kernels. These calculations suggest that the sensitivity of the deformations to the Earth's rheology is significant and strongly dependent on the location of the site relative to the ancient ice sheet. The effects on the predictions of three-dimensional deformation rates of altering the ice history or adopting approximate models for the ocean meltwater redistribution have also been considered and found to be important (the former especially so). Finally, for a suite of Earth models we provide predictions of the velocity of a number of baselines in North America and Europe. We find that, in general, both radial and tangential motions contribute significantly to baseline length changes, and that these contributions are a strong function of the Earth model. We have, furthermore, found a set of Earth models which, together with the ICE-3G deglaciation chronology, produce predictions of baseline length changes that are

  6. Fault Length Vs Fault Displacement Evaluation In The Case Of Cerro Prieto Pull-Apart Basin (Baja California, Mexico) Subsidence

    Science.gov (United States)

    Glowacka, E.; Sarychikhina, O.; Nava Pichardo, F. A.; Farfan, F.; Garcia Arthur, M. A.; Orozco, L.; Brassea, J.

    2013-05-01

    The Cerro Prieto pull-apart basin is located in the southern part of San Andreas Fault system, and is characterized by high seismicity, recent volcanism, tectonic deformation and hydrothermal activity (Lomnitz et al, 1970; Elders et al., 1984; Suárez-Vidal et al., 2008). Since the Cerro Prieto geothermal field production started, in 1973, significant subsidence increase was observed (Glowacka and Nava, 1996, Glowacka et al., 1999), and a relation between fluid extraction rate and subsidence rate has been suggested (op. cit.). Analysis of existing deformation data (Glowacka et al., 1999, 2005, Sarychikhina 2011) points to the fact that, although the extraction changes influence the subsidence rate, the tectonic faults control the spatial extent of the observed subsidence. Tectonic faults act as water barriers in the direction perpendicular to the fault, and/or separate regions with different compaction, and as effect the significant part of the subsidence is released as vertical displacement on the ground surface along fault rupture. These faults ruptures cause damages to roads and irrigation canals and water leakage. Since 1996, a network of geotechnical instruments has operated in the Mexicali Valley, for continuous recording of deformation phenomena. To date, the network (REDECVAM: Mexicali Valley Crustal Strain Measurement Array) includes two crackmeters and eight tiltmeters installed on, or very close to, the main faults; all instruments have sampling intervals in the 1 to 20 minutes range. Additionally, there are benchmarks for measuring vertical fault displacements for which readings are recorded every 3 months. Since the crackmeter measures vertical displacement on the fault at one place only, the question appears: can we use the crackmeter data to evaluate how long is the lenth of the fractured fault, and how quickly it grows, so we can know where we can expect fractures in the canals or roads? We used the Wells and Coppersmith (1994) relations between

  7. Investigation of subsidence in the Manfredonia Gulf (Southern Italy) through multitemporal DInSAR techniques

    Science.gov (United States)

    Triggiani, M.; Refice, A.; Capolongo, D.; Bovenga, F.; Caldara, M.

    2009-04-01

    We present results of an experiment aimed at detecting possible displacements due to subsidence in the coastal area of the Tavoliere plain, Puglia Region, in Southern Italy, through analysis of remotely sensed data. The Tavoliere is the second largest Italian plain. Its coastal area, between the urban centers of Manfredonia and Barletta, is composed of a 50 km long sandy beach (Manfredonia gulf), linking the Gargano massif at north with the Murge plateau in the south-east. Both areas belong to the carbonate Mesozoic Apulian platform. The current configuration of the Gulf was reached recently, as a consequence of the Holocene sea level rise. During the Neolithic age the plain was occupied by an elongated lagoon (Salpi Lagoon) [1]. During the 2nd century B.C., alluvial deposition caused the lagoon to be separated into two basins: the so-called Salpi lake at south and the Salso lake at north. To cope with the increasing demand of arable lands and with the necessity to make unhealthy areas accessible to humans, some reclaims were accomplished by diverting and channelling the rivers crossing the Tavoliere plain, and by levelling dune belts. At present, the beach is separated by low artificial dunes from the areas already reclaimed and intensely cultivated or exploited as evaporation basin for salt production. In the last decades, the coastal area has been retreating due to a reduction in sediment input necessary for coastal equilibrium. The levelling of dunes and the decrease of fluvial turbid discharge due to dam constructions a