WorldWideScience

Sample records for sahel

  1. Sahel Medical Journal

    African Journals Online (AJOL)

    ... Journal is a quarterly international Journal devoted solely to (1) dissemination of information about medical sciences in Nigeria, particularly the Sahel zone, Africa and the rest of the world, (2) to provide a medium where national and international medical and health organizations may relay information to medical scientists ...

  2. Security in the Sahel

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi

    In Niger, building more border offices has proven insufficient to tackle the spread of smuggling, drug trade and circulation of jihadists in the Sahel. Instead, everyday petty corruption makes border control ineffective and, while apparently benign, this has severe consequences in contexts...

  3. Sahel Journal of Veterinary Sciences

    African Journals Online (AJOL)

    The Sahel Journal of Veterinary Sciences is the official journal of the Faculty of Veterinary Medicine, University of Maiduguri, Maiduguri, Nigeria. The journal welcomes original research articles, short communications and reviews on all aspects of veterinary sciences and related disciplines.

  4. Environmental change in the Sahel

    DEFF Research Database (Denmark)

    Rasmussen, Kjeld; D'haen, Sarah Ann Lise; Fensholt, Rasmus

    2016-01-01

    The Sahel has been the object of intensive international research since the drought of the early 1970s. A considerable part of the research has focused on environmental change in general and land degradation, land cover change and climate change in particular. Rich and diverse insights from many...... different scientific disciplines about these three domains have been put forward. One intriguing feature is that an agreement on the overall trends of environmental change does not appear to emerge: questions such as whether the Sahel is greening, cropland is encroaching on rangelands, drought persists...... and choice of indicators, (2) biases, for example, related to selection of study sites, methodological choices, measurement accuracy, perceptions among interlocutors, and selection of temporal and spatial scales of analysis. The analysis of the root causes for different interpretations suggests...

  5. Migrations and nutritional status in the sahel.

    Science.gov (United States)

    Autier, P; D'Altilia, J P; Callewaert, B; Tamboura, B; Delamalle, J P; Vercruysse, V

    1989-09-01

    In the Sahel, migration is of considerable importance. It permits the peasants to adjust to variable food conditions. In areas affected by food shortages, cluster sample studies of villages showed that, as the number of recently abandoned houses in a cluster increased, the prevalence of malnutrition decreased, and this linear trend was significant (p nutritional surveillance. The article provides also a brief description of the current migration patterns in the Sahel and underlines the effects droughts have had on them.

  6. Terrorism, ethnicity and Islamic extremism in Sahel

    OpenAIRE

    Galito, Maria Sousa

    2012-01-01

    Terrorism is a threat in the Sahel region, where peoples and rulers seem to be losing control of the situation. Yet, the true origins of the instability are questionable. Ethnical conflicts and the religious differences, especially those related with the spreading of Islamic extremism among the local population, are two of the main reasons. This research paper analyzes different theories so as to attain some answers to these issues.

  7. Terrorism, ethnicity and Islamic extremism in Sahel

    Directory of Open Access Journals (Sweden)

    Maria Sousa Galito

    2012-01-01

    Full Text Available Terrorism is a threat in the Sahel region, where peoples and rulers seem to be losing control of the situation. Yet, the true origins of the instability are questionable. Ethnical conflicts and the religious differences, especially those related with the spreading of Islamic extremism among the local population, are two of the main reasons. This research paper analyzes different theories so as to attain some answers to these issues.

  8. Heavy Metal Concentrations In A West African Sahel Reservoir ...

    African Journals Online (AJOL)

    ... mean concentrations varied significantly between stations (P<0.05). The concentrations of heavy metals were below contamination levels and fall within the limits reported for other West African small sahel reservoirs. Keywords: Heavy metals, Pollutants, Environment, Alau reservoir, Sahel, Enrichment Animal Research ...

  9. [Sexuality of adolescents in the Sahel].

    Science.gov (United States)

    1997-01-01

    The major results are presented of a study of adolescent sexuality in five Sahel countries: Burkina Faso, Gambia, Mali, Niger, and Senegal. Because of strong taboos on discussing sexuality, most studies of reproductive health in the region have paid little attention to adolescents, who constitute over one-fifth of reproductive-age women. Awareness of problems in adolescent reproductive health is limited. Marriage age in the five countries is among the lowest in the world. In urban areas marriage age is increasing, but premarital sex is becoming more common. 51% of uneducated rural girls in Niger are married by age 15, as are 26% who are educated. But at age 20, 38% in Ouagadougou, 52% in Niamey, and 71% in Dakar are still single. Early marriage in the Sahel is usually followed rapidly by a pregnancy in an immature adolescent. The medical consequences of early pregnancy are a public health problem: spontaneous abortion, premature or difficult deliveries, high cesarean rates, infections, fistulas, trauma to the newborn, and low birth weight. Premarital sexual activity carries the same risks of early pregnancy, with the additional social and economic consequences inherent in non-marital fertility. Unwanted pregnancy, illegal abortion, or even infanticide may occur. The proportion of single mothers under age 20 varies from 9% to 18% in the large cities of the Sahel. Adolescents appear to be especially vulnerable to sexually transmitted diseases and HIV infection in case of unprotected sex, possibly because of their physical immaturity. Knowledge of sexually transmitted diseases is limited among girls, and most do not know that seemingly healthy persons can be HIV seropositive. Friends and the media are the most common sources of information about sex, and health agents, family members, and teachers are among the least frequent sources. Most older respondents agreed that premarital sexual activity has increased. Various explanations including later marriage and economic

  10. The Sahel: drought, desertification and famine.

    Science.gov (United States)

    Timberlake, L

    1985-09-01

    Between the end of Sahel's 1968-73 drought and the early 1980s, the production of the drought-resistant sorghum and millet was increasing at about 1% a year, but simultaneously the population was growing by about 2.5% a year. A 1982 UN study of the developing world's carrying capacity found that given the current low levels of agricultural technology used, about half the Sahelian countries could not be expected to feed themselves. The Sahel's demographic picture is complicated by the way different populations fill the various rainfall zones. The Sahelo-Saharan zone, the land of the nomad herders, can support a human density of only 0.3 people per square kilometer, but the density is actually 2 per square kilometer. The zone to the south, where herders and settled farmers mix, can support 15 people per square kilometer, yet it actually supports 20. the Sudano-Guinean zone at the far south may be able to support a larger population, but it has not been settled in part becuase it has spawned the tsetse fly and black fly. The region's rapidly growing population requires increased food production, yet the Sahelian countries have opted to encourage the cultivation of cash crops, especially cotton and peanuts, at the expense of food crops. Governments now are caught in the trap of depending on commodities, which are delcining in price, to pay rising debts. Extension advice, fertilizer, equipment, and marketing services are in short supply. In response to urban population pressure, Sahelian governments have kept food prices artificially low. With cities growing at an average annual rate of between 4-9%, national leaders fear social disruption and political instability if basic food needs at low prices are not met in the large cities. This policy inadvertently discourages food production. Meanwhile, the food situation for the region as a whole deteriorates to a calamity situation. The pressures of population growth and the emphasis on cash crops have forced families to try

  11. Breastfeeding and popular aetiology in the Sahel.

    Science.gov (United States)

    van de Walle, E; van de Walle, F

    1991-04-01

    Two views about breastfeeding and the resumption of intercourse after a birth are found to prevail in Bamako and Bobo-Dioulasso, two cities of the Sahel region of Africa: that sexual relations may spoil the milk; and that a child should be weaned when the woman is pregnant again. Both beliefs provide a rationale to abstain, but the postpartum taboo has been greatly reduced in the area, and the second belief is the most important. 'Bad milk' serves as an explanation for many of the diarrhoeas and diseases of nutritional origin that affect infants and children. Traditional medical treatments of diarrhoea and protein calorie malnutrition are consistent with the popular aetiology. The acceptance of modern techniques of infant care in this area may well be predicated on the diffusion of an alternative model of disease causation.

  12. Exploring land use change in the Sahel

    DEFF Research Database (Denmark)

    Rasmussen, Laura Vang

    the last decades and how local people’s land use decisions are influenced by various factors such as crop prices, off-farm job opportunities and rainfall variability. This is done by applying four complementary perspectives that represent different temporal and spatial scales as well as some influential...... theoretical lines of thought within the Land Change Science community. The four perspectives are system dynamics, resilience theory, a rationality perspective, and a multifunctional agriculture perspective. The thesis shows how the previous tendency to field expansion in the Sahel has been replaced by a very...... fluctuating cultivated area despite continued population growth. Instead, land use changes can be attributed to driving forces such as the possibilities of buying food crops at low prices in the local villages, and the engagement in non-agricultural activities such as migration and gold-digging. But recent...

  13. Damaging Rainfall and Flooding. The Other Sahel Hazards

    Energy Technology Data Exchange (ETDEWEB)

    Tarhule, A. [Department of Geography, University of Oklahoma, 100 East Boyd Street, Norman, OK, 73079 (United States)

    2005-10-01

    Damaging rainfall and rain-induced flooding occur from time to time in the drought-prone Sahel savannah zone of Niger in West Africa but official records of these events and their socioeconomic impacts do not exist. This paper utilized newspaper accounts between 1970 and 2000 to survey and illustrate the range of these flood hazards in the Sahel. During the study interval, 53 newspaper articles reported 79 damaging rainfall and flood events in 47 different communities in the Sahel of Niger. Collectively, these events destroyed 5,580 houses and rendered 27,289 people homeless. Cash losses and damage to infrastructure in only three events exceeded $4 million. Sahel residents attribute these floods to five major causes including both natural and anthropogenic, but they view the flood problem as driven primarily by land use patterns. Despite such awareness, traditional coping strategies appear inadequate for dealing with the problems in part because of significant climatic variability. Analysis of several rainfall measures indicates that the cumulative rainfall in the days prior to a heavy rain event is an important factor influencing whether or not heavy rainfall results in flooding. Thus, despite some limitations, newspaper accounts of historical flooding are largely consistent with measured climatic variables. The study demonstrates that concerted effort is needed to improve the status of knowledge concerning flood impacts and indeed other natural and human hazards in the Sahel.

  14. Impact of internal variability on projections of Sahel precipitation change

    Science.gov (United States)

    Monerie, Paul-Arthur; Sanchez-Gomez, Emilia; Pohl, Benjamin; Robson, Jon; Dong, Buwen

    2017-11-01

    The impact of the increase of greenhouse gases on Sahelian precipitation is very uncertain in both its spatial pattern and magnitude. In particular, the relative importance of internal variability versus external forcings depends on the time horizon considered in the climate projection. In this study we address the respective roles of the internal climate variability versus external forcings on Sahelian precipitation by using the data from the CESM Large Ensemble Project, which consists of a 40 member ensemble performed with the CESM1-CAM5 coupled model for the period 1920–2100. We show that CESM1-CAM5 is able to simulate the mean and interannual variability of Sahel precipitation, and is representative of a CMIP5 ensemble of simulations (i.e. it simulates the same pattern of precipitation change along with equivalent magnitude and seasonal cycle changes as the CMIP5 ensemble mean). However, CESM1-CAM5 underestimates the long-term decadal variability in Sahel precipitation. For short-term (2010–2049) and mid-term (2030–2069) projections the simulated internal variability component is able to obscure the projected impact of the external forcing. For long-term (2060–2099) projections external forcing induced change becomes stronger than simulated internal variability. Precipitation changes are found to be more robust over the central Sahel than over the western Sahel, where climate change effects struggle to emerge. Ten (thirty) members are needed to separate the 10 year averaged forced response from climate internal variability response in the western Sahel for a long-term (short-term) horizon. Over the central Sahel two members (ten members) are needed for a long-term (short-term) horizon.

  15. Life on the edge: vulnerability in the Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, Vanessa [Africa Hunger Advisor, Care International UK (United Kingdom)

    2007-07-15

    Locusts, drought, crops crumbling into dust: in 2005, the Sahel was hit by a catastrophic food crisis. Eight million people were affected. Two years on, drought has eased in this arid strip south of the Sahara, but its people still live in the grip of extreme vulnerability. Their condition is a crisis in itself and a near-guarantee of more humanitarian disasters in the region, whatever the force or frequency of future shocks. Aid donors need to recognise this vulnerability as the root cause of the Sahel's rolling crises.

  16. Aspects of the Hematology and Serum Biochemistry of Sahel and ...

    African Journals Online (AJOL)

    This study was conducted to investigate effects of year, age, season and breeds on aspects of the hematology and serum biochemical indices of Sahel and Sokoto red bucks in Mubi, Adamawa state, Nigeria. Blood and serum samples were used to determine PCV, Hb, RBC and WBC, and while serum protein (BSP) and ...

  17. Vegetation improvement and soil biological quality in the Sahel of ...

    African Journals Online (AJOL)

    ... processes have not significantly improved soil biological quality. It is concluded that vegetation improvement might be at the beginning stage in the Sahel, especially in croplands, and clear change of soil biological quality is not perceptible but may be tangible in the future. Keywords: Macro-fauna, ecosystem, soil quality, ...

  18. Agriculture, livelihoods and climate change in the West African Sahel

    NARCIS (Netherlands)

    Sissoko, K.; Keulen, van H.; Verhagen, A.; Tekken, V.; Battaglini, A.

    2011-01-01

    The West African Sahel is a harsh environment stressed by a fast-growing population and increasing pressure on the scarce natural resources. Agriculture is the main source of livelihood of the majority of the people living in the area. Increases in temperature and/or modifications in rainfall

  19. Phenotypic drift in osmotic fragility of Sahel goat erythrocytes ...

    African Journals Online (AJOL)

    Abstract. A typical mammalian erythrocyte fragility phenotype (EFP) exhibits a sigmoidal curve of the dependence of fragilities (% haemolysis) on hypotonic saline concentrations, but the goat EFP tends to be hyperbolic. Physiological variation in median erythrocyte fragility (MEF) and the associated EFP of Sahel goats was ...

  20. Tropical SST and Sahel rainfall: A non-stationary relationship

    Science.gov (United States)

    Losada, T.; Rodriguez-Fonseca, B.; Mohino, E.; Bader, J.; Janicot, S.; Mechoso, C. R.

    2012-06-01

    Sea surface temperature (SST) anomalies in the tropical Atlantic have been associated with precipitation anomalies in West Africa that form a dipole pattern with centers over the Sahel and the Gulf of Guinea. Whilst this was clear before the 1970's, the dipole pattern almost disappeared after that date, as the anti-correlation between rainfall anomalies in the Sahel and Guinea dropped abruptly. Simultaneously, the anti-correlations between Sahel rainfall and tropical Pacific SSTs strengthened. It has been posited that these changes after the 1970's developed as rainfall over West Africa started to co-vary with SSTs in the global tropics. In this co-variability, enhanced summer rainfall over West Africa with a monopole pattern corresponds to warmer SSTs in the tropical Atlantic and Maritime Continent, and colder SSTs in the tropical Pacific and western Indian Oceans. The present paper describes the hitherto unexplored seasonal evolution of this co-variability and the physical mechanisms at work. Sensitivity experiments with two atmospheric general circulation models demonstrate that, after the 1970's, the impacts of SST anomalies in the Indo-Pacific counteract those in the Atlantic in terms of generating rainfall anomalies over the Sahel, and that this superposition of effects is primarily linear. Therefore, at interannual timescales, the change in the patterns of co-variability between West African rainfall and tropical SSTs can explain the non-stationary relationship between the anomalies in these two fields.

  1. Extensive Admixture and Selective Pressure Across the Sahel Belt

    Czech Academy of Sciences Publication Activity Database

    Triska, P.; Soares, P.; Patin, E.; Fernandes, V.; Černý, Viktor; Pereira, L.

    2015-01-01

    Roč. 7, č. 12 (2015), s. 3484-3495 ISSN 1759-6653 R&D Projects: GA ČR GA13-37998S Institutional support: RVO:67985912 Keywords : genome-wide diversity * admixture * selection * Sahel Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 4.098, year: 2015 http://gbe.oxfordjournals.org/content/7/12/3484.full.pdf+html

  2. The Logistics Of The War In The Sahel

    Directory of Open Access Journals (Sweden)

    Gary K Busch

    2013-06-01

    Full Text Available There are both positive and negative aspects of waging a counter-insurgency war in the Sahel. The impediments are easy to see. The terrain of the Sahel does not lend itself to conventional warfare. There are broad expanses of sand and dunes, broken up by small villages and, occasionally, a town or city. There are no petrol stations, wells, repair shops, water stores, food stocks or fuel reserves in most of the region. Trucks and buses, as well as conventional armour, are difficult to transport in such a terrain. Air bases are usually suited only to small aircraft and lack the fuel and equipment which allow the free flow of cargo. African insurgents are bands and groups of often, irregular soldiers. On the positive side, the lack of ground cover and a tree canopy in the region enables a strategy of using the most modern weapons, the Unmanned Aerial Vehicles (UAV which can seek out, observe and destroy small and mobile enemy forces. This has meant that the logistic demands of the war in the Sahel has generated a strategy of high-tech weaponry deployed by Western forces combined with African troops on the ground as garrison forces for towns and cities.

  3. Characterization of Heat Waves in the Sahel and associated mechanisms

    Science.gov (United States)

    Oueslati, Boutheina; Pohl, Benjamin; Moron, Vincent; Rome, Sandra

    2016-04-01

    Large efforts are made to investigate the heat waves (HW) in developed countries because of their devastating impacts on society, economy and environment. This interest increased after the intense event over Europe during summer 2003. However, HWs are still understudied over developing countries. This is particularly true in West Africa, and especially in the Sahel, where temperatures recurrently reach critical values, such as during the 2010 HW event. Understanding the Sahelian HWs and associated health risks constitute the main objective of ACASIS, a 4-year project funded by the French Agence Nationale de la Recherche. Our work contributes to this project and aims at characterizing the Sahelian HWs and understanding the mechanisms associated with such extreme events. There is no universal definition of a HW event, since it is highly dependent on the sector (human health, agriculture, transport...) and region of interest. In our case, a HW is defined when the heat index of the day and of the night exceeds the 90th percentile for at least 3 consecutive days (Rome et al. 2016, in preparation). This index combines temperature and relative humidity in order to determine the human-perceived equivalent temperature (definition adapted from Steadman, 1979). Intrinsic properties of Sahelian HW are analyzed from the Global Summary of the Day (GSOD) synoptic observations and ERA-interim reanalyses over 1979-2014 during boreal spring seasons (April-May-June), the warmest period of the year in the Central Sahel. ERA-interim captures well the observed interannual variability and seasonal cycle at the regional scale, as well as the 1979-2014 increasing linear trend of springtime HW occurrences in the Sahel. Reanalyses, however, overestimate the duration, spatial extent of HW, and underestimate their intensity. For both GSOD and ERA-interim, we show that, over the last three decades, Sahelian HWs tend to become more frequent, last longer, cover larger areas and reach higher

  4. Women's Right to Water for Agricultural Use in the Sahel (Mauritanie ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Women's Right to Water for Agricultural Use in the Sahel (Mauritanie, Niger, Sénégal). Rural women in the Sahel are dynamic and important actors in the subsistence of their communities, especially in a context of male migration and the exploitation of hydro development for agriculture. This grant will allow the Réseau ...

  5. The local impacts of climate change in the Ferlo, Western Sahel

    NARCIS (Netherlands)

    Hein, L.G.; Metzger, M.J.; Leemans, R.

    2009-01-01

    Recent increases in the accuracy of climate models have enhanced the possibilities for analyzing the impacts of climate change on society. This paper explores how the local, economic impacts of climate change can be modeled for a specific eco-region, the Western Sahel. The people in the Sahel are

  6. Evaporation, sensible heat and canopy conductance of fallow savannah and patterned woodland in the Sahel

    NARCIS (Netherlands)

    Kabat, P.; Dolman, A.J.; Elbers, J.A.

    1997-01-01

    The behaviour of evaporation, sensible heat and canopy conductance of fallow savannah and patterned woodland in the Sahel is studied for the HAPEX-Sahel Intensive Observation Period. Both fallow savannah and patterned woodland reach evaporation rates of 4–5 mm day−1 during the rainy part of the IOP

  7. Decadal prediction of Sahel rainfall using dynamics-based indices

    Science.gov (United States)

    Otero, Noelia; Mohino, Elsa; Gaetani, Marco

    2016-12-01

    At decadal time scales, the capability of state-of-the-art atmosphere-ocean coupled climate models in predicting the precipitation in Sahel is assessed. A set of 14 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) is selected and two experiments are analysed, namely initialized decadal hindcasts and forced historical simulations. Considering the strong linkage of the atmospheric circulation signatures over West Africa with the rainfall variability, this study aims to investigate the potential of using wind fields for decadal predictions. Namely, a West African monsoon index (WAMI) is defined, based on the coherence of low (925 hPa) and high (200 hPa) troposphere wind fields, which accounts for the intensity of the monsoonal circulation. A combined empirical orthogonal functions analysis is applied to explore the wind fields' covariance modes, and a set of indices is defined on the basis of the identified patterns. The WAMI predictive skill is assessed by comparing WAMI from coupled models with WAMI from reanalysis products and with a standardized precipitation index (SPI) from observations. Results suggest that the predictive skill is highly model dependent and it is strongly related to the WAMI definition. In addition, hindcasts are more skilful than historical simulations in both deterministic and probability forecasts, which suggests an added value of initialization for decadal predictability. Moreover, coupled models are more skilful in predicting the observed SPI than the WAMI obtained from reanalysis. WAMI performance is also compared with decadal predictions from CMIP5 models based on a Sahelian precipitation index, and an improvement in predictive skill is observed in some models when WAMI is used. Therefore, we conclude that dynamics-based indices are potentially more effective for decadal prediction of precipitation in Sahel than precipitation-based indices for those models in which Sahel rainfall variability is not well

  8. Wars and conflicts in the Sahara-Sahel

    DEFF Research Database (Denmark)

    Walther, Olivier

    the traditional lines between what is local and global, military and civilian, domestic and international, politics and identity. The purpose of this paper is to analyse these patterns of violence. The first section presents the geographic distribution and development over time of the main sources of violence...... in North and West Africa before examining the events behind the increase in political violence in the Sahel and the Sahara. The second section analyses the patterns of violence, and focuses on the geographic scales thereof and the strategies of the warring parties. In its conclusion, the paper highlights...

  9. Using Relative Humidity Forecasts to Manage Meningitis in the Sahel

    Science.gov (United States)

    Pandya, R. E.; Adams-Forgor, A.; Akweogno, P.; Awine, T.; Dalaba, M.; Dukic, V.; Dumont, A.; Hayden, M.; Hodgson, A.; Hopson, T. M.; Hugonnet, S.; Yoksas, T. C.

    2012-12-01

    Meningitis epidemics in the Sahel occur quasi-regularly and with devastating impact. In 2008, for example, eighty-eight thousand people contracted meningitis and over five thousand died. Until very recently, the protection provided by the only available vaccine was so limited and short-lived that the only practical strategy for vaccination was reactive: waiting until an epidemic occurred in the region and then vaccinating in that region to prevent the epidemic's further growth. Even with that strategy, there were still times when demand outpaced available vaccine. While a new vaccine has recently been developed that is effective and inexpensive enough to be used more broadly and proactively, it is only effective against the strain of bacteria that causes the most common kind of bacterial meningitis. As a result, there will likely be continued need for reactive vaccination strategies. It is widely known that meningitis epidemics in the Sahel occur only in the dry season. Our project investigated this relationship, and several independent lines of evidence demonstrate a robust relationship between the onset of the rainy season, as marked by weekly average relative humidity above 40%, and the end of meningitis epidemics. These lines of evidence include statistical analysis of two years of weekly meningitis and weather data across the Sahel, cross-correlation of ten years of meningitis and weather data in the Upper East region of northern Ghana, and high-resolution weather simulations of past meningitis seasons to interpolate available weather data. We also adapted two techniques that have been successfully used in public health studies: generalized additive models, which have been used to relate air quality and health, and a linearized version of the compartmental epidemics model that has been used to understand MRSA. Based on these multiple lines of evidence, average weekly relative humidity forecast two weeks in advance appears consistently and strongly related to

  10. Tree Density and Species Decline in the African Sahel Attributable to Climate

    Science.gov (United States)

    Gonzalez, Patrick; Tucker, Compton J.; Sy, H.

    2012-01-01

    Increased aridity and human population have reduced tree cover in parts of the African Sahel and degraded resources for local people. Yet, tree cover trends and the relative importance of climate and population remain unresolved. From field measurements, aerial photos, and Ikonos satellite images, we detected significant 1954-2002 tree density declines in the western Sahel of 18 +/- 14% (P = 0.014, n = 204) and 17 +/- 13% (P = 0.0009, n = 187). From field observations, we detected a significant 1960-2000 species richness decline of 21 +/- 11% (P = 0.0028, n = 14) across the Sahel and a southward shift of the Sahel, Sudan, and Guinea zones. Multivariate analyses of climate, soil, and population showed that temperature most significantly (P < 0.001) explained tree cover changes. Multivariate and bivariate tests and field observations indicated the dominance of temperature and precipitation, supporting attribution of tree cover changes to climate variability. Climate change forcing of Sahel climate variability, particularly the significant (P < 0.05) 1901-2002 temperature increases and precipitation decreases in the research areas, connects Sahel tree cover changes to global climate change. This suggests roles for global action and local adaptation to address ecological change in the Sahel.

  11. Uncertain soil moisture feedbacks in model projections of Sahel precipitation

    Science.gov (United States)

    Berg, Alexis; Lintner, Benjamin R.; Findell, Kirsten; Giannini, Alessandra

    2017-06-01

    Given the uncertainties in climate model projections of Sahel precipitation, at the northern edge of the West African Monsoon, understanding the factors governing projected precipitation changes in this semiarid region is crucial. This study investigates how long-term soil moisture changes projected under climate change may feedback on projected changes of Sahel rainfall, using simulations with and without soil moisture change from five climate models participating in the Global Land Atmosphere Coupling Experiment-Coupled Model Intercomparison Project phase 5 experiment. In four out of five models analyzed, soil moisture feedbacks significantly influence the projected West African precipitation response to warming; however, the sign of these feedbacks differs across the models. These results demonstrate that reducing uncertainties across model projections of the West African Monsoon requires, among other factors, improved mechanistic understanding and constraint of simulated land-atmosphere feedbacks, even at the large spatial scales considered here.Plain Language SummaryClimate model projections of Sahel rainfall remain notoriously uncertain; understanding the physical processes responsible for this uncertainty is thus crucial. Our study focuses on analyzing the feedbacks of soil moisture changes on model projections of the West African Monsoon under global warming. Soil moisture-atmosphere interactions have been shown in prior studies to play an important role in this region, but the potential feedbacks of long-term soil moisture changes on projected precipitation changes have not been investigated specifically. To isolate these feedbacks, we use targeted simulations from five climate models, with and without soil moisture change. Importantly, we find that climate models exhibit soil moisture-precipitation feedbacks of different sign in this region: in some models soil moisture changes amplify precipitation changes (positive feedback), in others they dampen them

  12. The influence of seasonal rainfall upon Sahel vegetation

    DEFF Research Database (Denmark)

    Proud, Simon Richard; Rasmussen, Laura Vang

    2011-01-01

    Throughout the Sahelian region of Africa, vegetation growth displays substantial inter-annual variation, causing widespread concern in the region as rain-fed agriculture and pastoralism are a means of sustenance for the predominantly rural population. Previously proposed factors behind variations...... include changes in total yearly rainfall, land-use change and migration. But these factors are not fully explanatory. This study addresses other possible factors for variation in vegetation patterns through the analysis of the Normalized Difference Vegetation Index (NDVI) produced by satellite sensors. We...... that if the start of the growing season, or the period in which the peak growth of vegetation occurs, is especially dry then plant growth may be stunted throughout the remainder of the season. These results enable better understanding of climate dynamics in the Sahel and allow more accurate forecasting of crop...

  13. Non-linear intensification of Sahel rainfall as a possible dynamic response to future warming

    Science.gov (United States)

    Schewe, Jacob; Levermann, Anders

    2017-07-01

    Projections of the response of Sahel rainfall to future global warming diverge significantly. Meanwhile, paleoclimatic records suggest that Sahel rainfall is capable of abrupt transitions in response to gradual forcing. Here we present climate modeling evidence for the possibility of an abrupt intensification of Sahel rainfall under future climate change. Analyzing 30 coupled global climate model simulations, we identify seven models where central Sahel rainfall increases by 40 to 300 % over the 21st century, owing to a northward expansion of the West African monsoon domain. Rainfall in these models is non-linearly related to sea surface temperature (SST) in the tropical Atlantic and Mediterranean moisture source regions, intensifying abruptly beyond a certain SST warming level. We argue that this behavior is consistent with a self-amplifying dynamic-thermodynamical feedback, implying that the gradual increase in oceanic moisture availability under warming could trigger a sudden intensification of monsoon rainfall far inland of today's core monsoon region.

  14. Location and Permanency of Water Bodies in the African Sahel Region from 2003-2011

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides an estimate of the spatial and temporal extent of surface water at 250-m resolution over nine years (2003-2011) for the African Sahel region...

  15. Observed Change in Sahel Rainfall, Circulations, African Easterly Waves, and Atlantic Hurricanes Since 1979

    OpenAIRE

    Shih-Yu Wang; Gillies, Robert R.

    2011-01-01

    Here, we examine the dynamic properties associated with the recent increase in the Sahel rainfall using an ensemble of five global reanalysis datasets (1979–2010). The rainfall that has been observed to be increasing over the Sahel is accounted for by enhancements in both the tropical easterly jet and the African easterly jet, both of which are known to induce wet anomalies. Moreover, positional shifts in the African easterly jet and African easterly waves (AEWs) accompanied the northward m...

  16. Desertification and a shift of forest species in the West African Sahel

    Science.gov (United States)

    Gonzalez, Patrick

    2001-01-01

    Original field data show that forest species richness and tree density in the West African Sahel declined in the last half of the 20th century. Average forest species richness of areas of 4 km2 in Northwest Senegal fell from 64 ?? 2 species ca 1945 to 43 ?? 2 species in 1993, a decrease significant at p desertification in the West African Sahel. These documented impacts of desertification foreshadow possible future effects of climate change.

  17. The hydrogeological conditions in Sahel Hasheesh, Eastern Desert, Eg

    Directory of Open Access Journals (Sweden)

    Mohamed A. Abdalla

    2016-06-01

    Full Text Available The groundwater development in Egypt in the present time is of a vital importance than in past few years. A comprehensive plan for new land reclamation projects has been recently established. To achieve these plans new sources of water must be available. This has been done by conducting a number of VES’S where interpreted by a comparison with the existing drilled borehole soil samples. The optimum resistivity model is obtained by matching method using “IPI2Win” Moscow State University 2000 software computer programs for resistivity interpretation. The results of the quantitative interpretation of the resistivity curves has been represented as geoelectric sections, showing the thickness and true electric resistivity values of the different geoelectric layers. The results of quantitative interpretation of the vertical electrical soundings show subsurface five geoelectric units and the aquifer system belongs to lower Miocene and the total salinity of 2451.2 ppm. The depth to water surface is 88.05 m and the total dissolved solids are 2451.2 ppm (Mekhemer well. The salt assemblages in Sahel Hasheesh are NaCl, MgCl2, MgSO4, CaSO4, Ca(HCO32. This marine water is of brackish sodium chloride water type (NaCl.

  18. Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales

    Science.gov (United States)

    Sheen, K. L.; Smith, D. M.; Dunstone, N. J.; Eade, R.; Rowell, D. P.; Vellinga, M.

    2017-05-01

    Summer rainfall in the Sahel region of Africa exhibits one of the largest signals of climatic variability and with a population reliant on agricultural productivity, the Sahel is particularly vulnerable to major droughts such as occurred in the 1970s and 1980s. Rainfall levels have subsequently recovered, but future projections remain uncertain. Here we show that Sahel rainfall is skilfully predicted on inter-annual and multi-year (that is, >5 years) timescales and use these predictions to better understand the driving mechanisms. Moisture budget analysis indicates that on multi-year timescales, a warmer north Atlantic and Mediterranean enhance Sahel rainfall through increased meridional convergence of low-level, externally sourced moisture. In contrast, year-to-year rainfall levels are largely determined by the recycling rate of local moisture, regulated by planetary circulation patterns associated with the El Niño-Southern Oscillation. Our findings aid improved understanding and forecasting of Sahel drought, paramount for successful adaptation strategies in a changing climate.

  19. Observed Change in Sahel Rainfall, Circulations, African Easterly Waves, and Atlantic Hurricanes Since 1979

    Directory of Open Access Journals (Sweden)

    Shih-Yu Wang

    2011-01-01

    Full Text Available Here, we examine the dynamic properties associated with the recent increase in the Sahel rainfall using an ensemble of five global reanalysis datasets (1979–2010. The rainfall that has been observed to be increasing over the Sahel is accounted for by enhancements in both the tropical easterly jet and the African easterly jet, both of which are known to induce wet anomalies. Moreover, positional shifts in the African easterly jet and African easterly waves (AEWs accompanied the northward migration of the Sahel rainband. Change in the African easterly jet and AEWs are coupled to a northward shift and amplification of convective activity; this signals an increased potential for the occurrence of flash floods along the northern Sahel. In addition, the result from a wave tracking analysis suggests that the change in AEWs is closely linked to increased activity of intense hurricanes in the North Atlantic. The synoptic concurrence of AEWs in driving the dynamics of the Sahel greening and the increase in tropical cyclogeneses over the North Atlantic is an important aspect in the evaluation of climate model projections.

  20. U.S. Army Civil Affairs Forces in the Sahel: Developing an Approach to Building Relevant Partner Capacity in Support of U.S. Africa Command

    Science.gov (United States)

    2015-06-12

    Sahel is necessary. The Sahel is a semi - arid region in North Africa stretching from Senegal to Sudan. The name Sahel derives from the Arabic word sāḥil......growing instability with the potential to affect security in other parts of the globe. Climate change, ethnic tensions, crushing poverty, and

  1. Ground-and satellite-based evidence of the biophysical mechanisms behind the greening Sahel

    DEFF Research Database (Denmark)

    Brandt, Martin Stefan; Mbow, Cheikh; Diouf, Abdoul A.

    2015-01-01

    remain speculative. Our aim is to bridge these gaps and give specifics on the biophysical background factors of the re-greening Sahel. Therefore, a trend analysis was applied on long time series (1987-2013) of satellite-based vegetation and rainfall data, as well as on ground-observations of leaf biomass...... of woody species, herb biomass, and woody species abundance in different ecosystems located in the Sahel zone of Senegal. We found that the positive trend observed in satellite vegetation time series (+36%) is caused by an increment of in situ measured biomass (+34%), which is highly controlled...... conclude that the observed greening in the Senegalese Sahel is primarily related to an increasing tree cover that caused satellite-driven vegetation indices to increase with rainfall reversal. Copyright...

  2. The blurred boundaries of political violence in the Sahel-Sahara

    DEFF Research Database (Denmark)

    Walther, Olivier

    2017-01-01

    The Sahel and the Sahara are faced with exceptional political instability involving a combination of rebellions, jihadist insurgencies, coups d’état, protest movements and illegal trafficking. Analysis of the outbreaks of violence reveals that the region is not just the victim of an escalation...... of wars and conflicts that marked the 20th century. The Sahel-Sahara has also become the setting of a globalised security environment, in which boundaries between what is local and global, domestic and international, military and civilian, politics and identity are blurred....

  3. Climate and Food Production: Understanding Vulnerability from Past Trends in Africa’s Sudan-Sahel

    Directory of Open Access Journals (Sweden)

    Genesis T. Yengoh

    2012-12-01

    Full Text Available Just how influential is rainfall on agricultural production in the Sudan-Sahel of Africa? And, is there evidence that support for small-scale farming can reduce the vulnerability of crop yields to rainfall in these sensitive agro-ecological zones? These questions are explored based on a case study from Cameroon’s Sudan-Sahel region. Climate data for 20 years and crop production data for six major food crops for the same years are used to find patterns of correlation over this time period. Results show a distinction of three periods of climatic influence of agriculture: one period before 1989, another between 1990 and 1999 and the last from 2000 to 2004. The analysis reveals that, while important in setting the enabling biophysical environment for food crop cultivation, the influence of rainfall in agriculture can be diluted by proactive policies that support food production. Proactive policies also reduce the impact of agriculturally relevant climatic shocks, such as droughts on food crop yields over the time-series. These findings emphasize the extent of vulnerability of food crop production to rainfall variations among small-holder farmers in these agro-ecological zones and reinforce the call for the proactive engagement of relevant institutions and support services in assisting the efforts of small-scale food producers in Africa’s Sudan-Sahel. The implications of climate variability on agriculture are discussed within the context of food security with particular reference to Africa’s Sudan-Sahel.

  4. Mercy or Wrath: The Competing Ideologies of Sufism and Wahhabism in North Africa and the Sahel

    Science.gov (United States)

    2013-06-10

    Association Pennsylvania State University. State College, Pennsylvania " Le Sahel: Les vulnerability et les nouveaux facteurs de l’insecurite...With Youssef Sawani. Al-Maaref. (Beirut) Book in Production (to be published August 2013) Revolution, Revolt, and Reform in North Africa: The

  5. Regime shifts in the Sahara and Sahel: interactions between ecological and climatic systems in northern Africa

    NARCIS (Netherlands)

    Foley, J.A.; Coe, M.T.; Scheffer, M.; Wang, G.L.

    2003-01-01

    The Sahara and Sahel regions of northern Africa have complex environmental histories punctuated by sudden and dramatic "regime shifts" in climate and ecological conditions. Here we review the current understanding of the causes and consequences of two environmental regime shifts in the Sahara and

  6. A model of tree-crop competition for windbreaks systems in the Sahel : description and evaluation

    NARCIS (Netherlands)

    Mayus, M.; Keulen, van H.; Stroosnijder, L.

    1999-01-01

    A model was developed to simulate the effects of competition for soil water and radiation between windbreaks and pearl millet crops in the Sahel. These effects on millet (Pennisetum glaucum (L.) R. Br.) growth were simultaneously simulated for each millet row parallel to the windbreak with small

  7. Revisiting the coupling between NDVI trends and cropland changes in the Sahel drylands

    DEFF Research Database (Denmark)

    Tong, Xiaoye; Brandt, Martin Stefan; Hiernaux, Pierre

    2017-01-01

    The impact of human activities via land use/cover changes on NDVI trends is critical for an improved understanding of satellite-observed changes in vegetation productivity in drylands. The dominance of positive NDVI trends in the Sahel, the so-called re-greening, is sometimes interpreted as a com...

  8. Dynamics of Poverty and Land Degradation in the Sahel (West Africa)

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project will attempt to breach this knowledge gap. Researchers in Burkina Faso and Niger will endeavor to understand the dynamics of poverty and land degradation, identify promising options for reducing poverty and land degradation, and promote pathways suited to different development contexts in the Sahel.

  9. An Advanced Review of the Relationships between Sahel Precipitation and Climate Indices: A Wavelet Approach

    Directory of Open Access Journals (Sweden)

    Churchill Okonkwo

    2014-01-01

    Full Text Available The interannual and decadal to multidecadal variability of precipitation in western Sahel region was examined using wavelet transform and coherency analysis. The aim was to identify the major climate index that has a robust relationship with Sahel precipitation (drought. The results show that ENSO, North Atlantic Oscillation (NAO, Atlantic Multidecadal Oscillation (AMO, and Indian Ocean Dipole (IOD all have some relationship with precipitation at different time scales which is in agreement with recent studies. There is an antiphase relationship between Sahel precipitation and ENSO at the 3-4-year band localized around 1982/83 El Niño episode. This indicates a cause and effect relationship between the droughts of 1983 and 1982/83 El Niño. In addition, wavelet transform coherence analysis also revealed a relatively antiphase relationship between AMO and precipitation signifying cause and effect. The wavelet analyses indicate that IOD control on rainfall variability in Sahel is limited to the east (15°E–35°E. Advancing this understanding of variability in rainfall and climate forcing could improve the accuracy of rainfall forecast.

  10. Termites and agricultural production in the Sahel: from enemy to friend?

    NARCIS (Netherlands)

    Mando, A.; Rheenen, van T.

    1998-01-01

    Termites are an important component of agroecosystems, particularly in developing countries where they are an alternative to high priced inputs. Given the major problems in the Sahel of soil crusting and nutrient depletion, this paper shows that termites associated with proper management techniques

  11. Disentangling the effects of climate and people on Sahel vegetation dynamics

    Directory of Open Access Journals (Sweden)

    J. W. Seaquist

    2009-03-01

    Full Text Available The Sahel belt of Africa has been the focus of intensive scientific research since the 1960s, spurred on by the chronic vulnerability of its population to recurring drought and the threat of long-term land degradation. But satellite sensors have recently shown that much of the region has experienced significant increases in photosynthetic activity since the early 1980s, thus re-energizing long-standing debates about the role that people play in shaping land surface status, and thus climate at regional scales. In this paper, we test the hypothesis that people have had a measurable impact on vegetation dynamics in the Sahel for the period 1982–2002. We compare potential natural vegetation dynamics predicted by a process-based ecosystem model with satellite-derived greenness observations, and map the agreement between the two across a geographic grid at a spatial resolution of 0.5°. As aggregated data-model agreement is very good, any local differences between the two could be due to human impact. We then relate this agreement metric to state-of-the-art data sets on demographics, pasture, and cropping. Our findings suggest that demographic and agricultural pressures in the Sahel are unable to account for differences between simulated and observed vegetation dynamics, even for the most densely populated areas. But we do identify a weak, positive correlation between data-model agreement and pasture intensity at the Sahel-wide level. This indicates that herding or grazing does not appreciably affect vegetation dynamics in the region. Either people have not had a significant impact on vegetation dynamics in the Sahel or the identification of a human "footprint" is precluded by inconsistent or subtle vegetation response to complex socio-environmental interactions, and/or limitations in the data used for this study. We do not exclude the possibility of a greater human influence on vegetation dynamics over the coming decades with changing land use.

  12. Desertification, resilience, and re-greening in the African Sahel - a matter of the observation period?

    Science.gov (United States)

    Kusserow, Hannelore

    2017-12-01

    Since the turn of the millennium various scientific publications have been discussing a re-greening of the Sahel after the 1980s drought mainly based on coarse-resolution satellite data. However, the author's own field studies suggest that the situation is far more complex and that both paradigms, the encroaching Sahara and the re-greening Sahel, need to be questioned.This paper discusses the concepts of desertification, resilience, and re-greening by addressing four main aspects: (i) the relevance of edaphic factors for a vegetation re-greening, (ii-iii) the importance of the selected observation period in the debate on Sahel greening or browning, and (iv) modifications in the vegetation pattern as possible indicators of ecosystem changes (shift from originally diffuse to contracted vegetation patterns).The data referred to in this paper cover a time period of more than 150 years and include the author's own research results from the early 1980s until today. A special emphasis, apart from fieldwork data and remote sensing data, is laid on the historical documents.The key findings summarised at the end show the following: (i) vegetation recovery predominantly depends on soil types; (ii) when discussing Sahel greening vs. Sahel browning, the majority of research papers only focus on post-drought conditions. Taking pre-drought conditions (before the 1980s) into account, however, is essential to fully understand the situation. Botanical investigations and remote-sensing-based time series clearly show a substantial decline in woody species diversity and cover density compared to pre-drought conditions; (iii) the self-organised patchiness of vegetation is considered to be an important indicator of ecosystem changes.

  13. Trends and Variability in Pastoral Resources in the West African Sahel

    Science.gov (United States)

    Hanan, N. P.

    2014-12-01

    The geography of water and nutrients in the savannas of West Africa has shaped the development of a system of migratory cattle movements ("transhumance") in which herds travel north during the rainy season to graze the nutritious grasslands of the Sahel and return south in the dry season to graze in fallow lands and on agricultural residue. Cattle in this system gain most of their body mass while grazing in the Sahel and frequently lose mass on their dry season range. The Sahel is, therefore, at the heart of extensive livestock production systems in West Africa. However, there is increasing concern regarding how climate change will impact the region, while human population growth and economic development require increased agricultural and livestock production. The future for pastoral production systems in West Africa is, therefore, uncertain. This presentation combines remote sensing of vegetation structure and phenology with a watershed-scale tree-grass ecohydrology model, to explore how key resources for Sahelian pastoralist communities (forage and surface water for livestock, woody biomass for fuel) respond to climate variability and extreme events, conditioned by human management of grazing, fire and fuel-wood harvest. Mortality of woody species and loss of herbaceous cover during the Sahelian droughts of the 1970's and 1980's significantly perturbed vegetation dynamics and ecohydrological interactions, perturbations from which the region is still recovering. The re-greening and reforestation of the Sahel reported by many authors is, in part, an expression of this recovery. Future trajectories of change in pastoral resources in the Sahel, in particular forage availability and drinking water, are explored using climate change ensembles.

  14. Towards a parameterization of convective wind gusts in Sahel

    Science.gov (United States)

    Largeron, Yann; Guichard, Françoise; Bouniol, Dominique; Couvreux, Fleur; Birch, Cathryn; Beucher, Florent

    2014-05-01

    ] who focused on the wet tropical Pacific region, and linked wind gusts to convective precipitation rates alone, here, we also analyse the subgrid wind distribution during convective events, and quantify the statistical moments (variance, skewness and kurtosis) in terms of mean wind speed and convective indexes such as DCAPE. Next step of the work will be to formulate a parameterization of the cold pool convective gust from those probability density functions and analytical formulaes obtained from basic energy budget models. References : [Carslaw et al., 2010] A review of natural aerosol interactions and feedbacks within the earth system. Atmospheric Chemistry and Physics, 10(4):1701{1737. [Engelstaedter et al., 2006] North african dust emissions and transport. Earth-Science Reviews, 79(1):73{100. [Knippertz and Todd, 2012] Mineral dust aerosols over the sahara: Meteorological controls on emission and transport and implications for modeling. Reviews of Geophysics, 50(1). [Marsham et al., 2011] The importance of the representation of deep convection for modeled dust-generating winds over west africa during summer.Geophysical Research Letters, 38(16). [Marticorena and Bergametti, 1995] Modeling the atmospheric dust cycle: 1. design of a soil-derived dust emission scheme. Journal of Geophysical Research, 100(D8):16415{16. [Menut, 2008] Sensitivity of hourly saharan dust emissions to ncep and ecmwf modeled wind speed. Journal of Geophysical Research: Atmospheres (1984{2012), 113(D16). [Pierre et al., 2012] Impact of vegetation and soil moisture seasonal dynamics on dust emissions over the sahel. Journal of Geophysical Research: Atmospheres (1984{2012), 117(D6). [Redelsperger et al., 2000] A parameterization of mesoscale enhancement of surface fluxes for large-scale models. Journal of climate, 13(2):402{421.

  15. Migration internationale et dynamiques socio-spatiales dans le Sahel tunisien : le cas de la ville de Sayada

    National Research Council Canada - National Science Library

    Mandhouj, Makrem

    2008-01-01

    Known as being one of the most important migratory homes (centers) in the central Tunisian Sahel, the town of Sayada is a space of numerous socio-spatial dynamics, increasingly influenced by the effects of the international migration...

  16. Impact of vegetation removal and soil aridation on diurnal temperature range in a semiarid region: Application to the Sahel

    OpenAIRE

    Zhou, Liming; Robert E. Dickinson; Tian, Yuhong; Vose, Russell S.; Dai, YongJiu

    2007-01-01

    Increased clouds and precipitation normally decrease the diurnal temperature range (DTR) and thus have commonly been offered as explanation for the trend of reduced DTR observed for many land areas over the last several decades. Observations show, however, that the DTR was reduced most in dry regions and especially in the West African Sahel during a period of unprecedented drought. Furthermore, the negative trend of DTR in the Sahel appears to have stopped and may have reversed after the rain...

  17. Maladies fongiques des cucurbitacées dans le Sahel tunisien : inventaire, importance et conséquences agronomiques

    Directory of Open Access Journals (Sweden)

    Romdhani, MS.

    1984-01-01

    Full Text Available Fungal diseases of cucurbits in the Tunisian Sahel inventory, importance and agronomical consequences. An inventory of the mycoflora of the cultivated cucurbits in the Tunisian Sahel region is drawn up and the fungi are classified with regard to their importance. This is done in the nursery as well as in the crop grown under plastic houses. Control measures against the principal diseases are discussed.

  18. Unravelling biodiversity, evolution and threats to conservation in the Sahara-Sahel.

    Science.gov (United States)

    Brito, José C; Godinho, Raquel; Martínez-Freiría, Fernando; Pleguezuelos, Juan M; Rebelo, Hugo; Santos, Xavier; Vale, Cândida G; Velo-Antón, Guillermo; Boratyński, Zbyszek; Carvalho, Sílvia B; Ferreira, Sónia; Gonçalves, Duarte V; Silva, Teresa L; Tarroso, Pedro; Campos, João C; Leite, João V; Nogueira, Joana; Alvares, Francisco; Sillero, Neftalí; Sow, Andack S; Fahd, Soumia; Crochet, Pierre-André; Carranza, Salvador

    2014-02-01

    Deserts and arid regions are generally perceived as bare and rather homogeneous areas of low diversity. The Sahara is the largest warm desert in the world and together with the arid Sahel displays high topographical and climatic heterogeneity, and has experienced recent and strong climatic oscillations that have greatly shifted biodiversity distribution and community composition. The large size, remoteness and long-term political instability of the Sahara-Sahel, have limited knowledge on its biodiversity. However, over the last decade, there have been an increasing number of published scientific studies based on modern geomatic and molecular tools, and broad sampling of taxa of these regions. This review tracks trends in knowledge about biodiversity patterns, processes and threats across the Sahara-Sahel, and anticipates needs for biodiversity research and conservation. Recent studies are changing completely the perception of regional biodiversity patterns. Instead of relatively low species diversity with distribution covering most of the region, studies now suggest a high rate of endemism and larger number of species, with much narrower and fragmented ranges, frequently limited to micro-hotspots of biodiversity. Molecular-based studies are also unravelling cryptic diversity associated with mountains, which together with recent distribution atlases, allows identifying integrative biogeographic patterns in biodiversity distribution. Mapping of multivariate environmental variation (at 1 km × 1 km resolution) of the region illustrates main biogeographical features of the Sahara-Sahel and supports recently hypothesised dispersal corridors and refugia. Micro-scale water-features present mostly in mountains have been associated with local biodiversity hotspots. However, the distribution of available data on vertebrates highlights current knowledge gaps that still apply to a large proportion of the Sahara-Sahel. Current research is providing insights into key

  19. Understanding Pacific Ocean influence on interannual precipitation variability in the Sahel

    Science.gov (United States)

    Pomposi, Catherine; Giannini, Alessandra; Kushnir, Yochanan; Lee, Dong Eun

    2016-09-01

    Moisture budget decomposition is performed for the Sahel (10°-20°N and 20°W-40°E) in order to understand the processes that govern regional hydroclimate variability on interannual time scales and frame them in the context of their primary ocean driver. Results show that warm conditions in the Eastern Tropical Pacific remotely force anomalously dry conditions primarily through affecting the low-troposphere mass divergence field. This behavior is related to increased subsidence over the tropical Atlantic and into the Sahel and an anomalous westward flow of moisture from the continent, both resulting in a coherent drying pattern. Understanding the physical processes relating remote sea surface temperature anomalies to atmospheric circulation changes and the resulting complex local convergence patterns is important for advancing seasonal prediction of precipitation over West Africa.

  20. What four decades of earth observation tell us about land degradation in the Sahel?

    DEFF Research Database (Denmark)

    Mbow, Cheikh; Brandt, Martin Stefan; Ouedraogo, Issa

    2015-01-01

    in the Sahel. The large number of EO datasets and methods associated with the complex interactions among biophysical and social drivers of ecosystem changes make it difficult to apply aggregated EO indices for these non-linear processes. Hence, while many studies stress that the Sahel is greening, others...... indicate no trend or browning. The different generations of sensors, the granularity of studies, the study period, the applied indices and the assumptions and/or computational methods impact these trends. Consequently, many uncertainties exist in regression models between rainfall, biomass and various...... and assumptions, (6) set up a denser network of long-term field-surveys and (7) consider local perceptions and social dynamics. To allow multiple perspectives and avoid erroneous interpretations, we underline that EO results should not be interpreted without contextual knowledge....

  1. Genetic structure of pastoral and farmer populations in the African Sahel.

    Science.gov (United States)

    Černý, Viktor; Pereira, Luísa; Musilová, Eliška; Kujanová, Martina; Vašíková, Alžběta; Blasi, Paola; Garofalo, Luisa; Soares, Pedro; Diallo, Issa; Brdička, Radim; Novelletto, Andrea

    2011-09-01

    Traditional pastoralists survive in few places in the world. They can still be encountered in the African Sahel, where annual alternations of dry and wet seasons force them to continual mobility. Little is known about the genetic structure of these populations. We present here the population distribution of 312 hypervariable segment I mitochondrial DNA (mtDNA) and 364 Y-short tandem repeat haplotypes in both farmer and pastoralist groups from the Lake Chad Basin and the West African Sahel. We show that the majority of pastoral populations (represented in the African Sahel by the Fulani nomads) fail to show significant departure from neutrality for mtDNA as evidenced by Fu's Fs statistics and exhibit lower levels of intrapopulation diversity measures for mtDNA when contrasted with farmers. These differences were not observed for the Y chromosome. Furthermore, analyses of molecular variance and population distributions of the mtDNA haplotypes show more heterogeneity in the sedentary groups than in the pastoralists. On the other hand, pastoralists retain a signature of a wide phylogenetic distance contributing to their male gene pool, whereas in at least some of the farmer populations, a founder effect and/or drift might have led to the presence of a single major lineage. Interestingly, these observations are in contrast with those recorded in Central Asia, where similar comparisons of farmer and pastoral groups have recently been carried out. We can conclude that in Africa, there have been no substantial mating exchanges between the Fulani pastoralists coming to the Lake Chad Basin from the West African Sahel and their farmer neighbors. At the same time, we suggest that the emergence of pastoralism might be an earlier and/or a demographically more important event than the introduction of sedentary agriculture, at least in this part of Africa.

  2. Political Reform, Socio-Religious Change, and Stability in the African Sahel

    Science.gov (United States)

    2016-12-08

    climate change. KEYNOTE LECTURE I: Jean- Pierre Olivier de Sardan The Construction of States & Societies in the Sahel Beyond the colonial legacy...Comparatively surveying several “literary fields” in the sense of Bourdieu , this chapter examines the impact and the outcomes of the first set of...Linguistics. Jean- Pierre Olivier de Sardan is Professor of Anthropology at the Ecole des Hautes Etudes en Sciences Sociales, and Emeritus

  3. Hacia un nuevo y diferente “Flanco Sur” en el Gran Magreb-Sahel

    Directory of Open Access Journals (Sweden)

    Raquel Barras

    2015-10-01

    Full Text Available La unión de espacios subgobernados, la corrupción, el crimen organizado y terrorismo es la amenaza a la que se enfrenta la UE y sus estados miembros en el Gran Magreb, el cual está recreando un nuevo y diferente Flanco Sur al que existía durante la Guerra Fría. El aumento de la actividad extremista en la región del Sahel-Sáhara a partir de 2005 ha ido en paralelo con el crecimiento de las redes de crimen organizado transnacional a través del área. Aunque hay un intenso debate sobre su relación, intensidad e impacto, es una dinámica innegable en el área. La UE no tiene realmente una política unificada Magreb-Sahel y en términos de crimen organizado y terrorismo, el Sahel no se puede separar del Magreb. Hay una comprensión limitada y parcial del problema tanto en términos de amenazas como en soluciones viables, ampliado irremediablemente por la acción de Boko Haram y desbordando la visión, proyección y estrategia de la UE. A pesar del "Sahel Regional Action Plan 2015-2020", las medidas tomadas son reducidas, muy recientes y probablemente insuficientes y tardías desde el punto de vista de la dinámica y sinergia entre terrorismo-crimen organizado en un contexto de corrupción. La UE sigue manteniendo un enfoque seguridad-desarrollo, básicamente en una concepción de seguridad humana, a pesar de que este enfoque es altamente discutible para enfrentarse a este tipo de amenazas.

  4. Seasonal variation in metabolic rate, flight activity and body size of Anopheles gambiae in the Sahel.

    Science.gov (United States)

    Huestis, Diana L; Yaro, Alpha S; Traoré, Adama I; Dieter, Kathryne L; Nwagbara, Juliette I; Bowie, Aleah C; Adamou, Abdoulaye; Kassogué, Yaya; Diallo, Moussa; Timbiné, Seydou; Dao, Adama; Lehmann, Tovi

    2012-06-15

    Malaria in Africa is vectored primarily by the Anopheles gambiae complex. Although the mechanisms of population persistence during the dry season are not yet known, targeting dry season mosquitoes could provide opportunities for vector control. In the Sahel, it appears likely that M-form A. gambiae survive by aestivation (entering a dormant state). To assess the role of eco-physiological changes associated with dry season survival, we measured body size, flight activity and metabolic rate of wild-caught mosquitoes throughout 1 year in a Sahelian locality, far from permanent water sources, and at a riparian location adjacent to the Niger River. We found significant seasonal variation in body size at both the Sahelian and riparian sites, although the magnitude of the variation was greater in the Sahel. For flight activity, significant seasonality was only observed in the Sahel, with increased flight activity in the wet season when compared with that just prior to and throughout the dry season. Whole-organism metabolic rate was affected by numerous biotic and abiotic factors, and a significant seasonal component was found at both locations. However, assay temperature accounted completely for seasonality at the riparian location, while significant seasonal variation remained after accounting for all measured variables in the Sahel. Interestingly, we did not find that mean metabolic rate was lowest during the dry season at either location, contrary to our expectation that mosquitoes would conserve energy and increase longevity by reducing metabolism during this time. These results indicate that mosquitoes may use mechanisms besides reduced metabolic rate to enable survival during the Sahelian dry season.

  5. Astronomical forcing of an exceptionally long Sahel wet phase during Marine Isotope Stage 11c

    Science.gov (United States)

    Prange, Matthias; Rachmayani, Rima; Schulz, Michael

    2016-04-01

    Increased rainfall and expanded vegetation over North Africa during the early-to-mid Holocene was related to an intensified West African monsoon and a northward displacement of the monsoon trough triggered by astronomical forcing. Similar wet phases are evidenced for earlier interglacials including Marine Isotope Stage (MIS) 11c (ca. 425-395 ka before present). We performed a series of time slice simulations using the comprehensive coupled climate model CCSM3 including a dynamic vegetation module in order to examine the dynamics of the MIS 11c humid period. Proxy records from a marine sediment core site off Northwest Africa suggest an extremely long Sahel/Sahara wet phase during MIS 11c between ca. 420 and 405 ka ago, revealing that North African rainfall changes did not simply follow local summer insolation. Instead, the climate model simulations suggest an important role of the obliquity-driven intra-hemispheric insolation gradient in forcing Sahelian rainfall changes. The specific phasing between precession and obliquity during the MIS 11c interglacial resulted in the exceptionally long wet phase in the Sahel region. The early part of this wet phase was primarily induced by northern-hemispheric differential warming in response to maximum obliquity around 416 ka before present. As such, this interval may well serve as an analog for potential future Sahel rainfall increase induced by strong northern hemisphere extratropical warming.

  6. The Re-Greening of the Sahel: Natural Cyclicity or Human-Induced Change?

    Directory of Open Access Journals (Sweden)

    Issa Ouedraogo

    2014-09-01

    Full Text Available The Sahel has been the focus of scientific interest in environmental-human dynamics and interactions. The objective of the present study is to contribute to the recent debate on the re-greening of Sahel. The paper examines the dynamics of barren land in the Sahel of Burkina Faso through analysis of remotely-sensed and rainfall data from 1975–2011. Discussions with farmers and land management staff have helped to understand the anthropogenic efforts toward soil restoration to enable the subsistence farming agriculture. Results showed that area of barren land has been fluctuating during the study period with approximately 10-year cyclicity. Similarly, rainfall, both at national and local levels has followed the same trends. The trends of the area of barren land and rainfall variability suggest that when rainfall increases, the area of barren land decreases and barren land increases when rainfall decreases. This implies that rainfall is one of the main factors driving the change in area of barren land. In addition, humans have contributed positively and negatively to the change by restoring barren lands for agriculture using locally known techniques and by accelerating land degradation through intensive and inappropriate land use practices.

  7. Surface temperature and soil moisture retrieval in the Sahel from airborne multifrequency microwave radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Calvet, J.C. [Meteo-France/CNRM, Toulouse (France); Chanzy, A.; Wigneron, J.P. [Inst. National de la Recherche Agronomique, Avignon (France)

    1996-03-01

    Bipolarized microwave brightness temperatures of Sahel semiarid landscapes are analyzed at two frequencies: 5.05 and 36.5 GHz. These measurements were performed in Niger, West Africa, by the radiometer PORTOS in the framework of the Hydrologic Atmospheric Pilot Experiment in the Sahel (HAPEX-Sahel), during the end of the rainy season (August--September 1992). The airborne microwave data were collected simultaneously with radiosoundings of the atmosphere, and ground measurements of surface temperature, soil moisture, and biomass of several vegetation types. After estimating the soil roughness parameters, it is shown that two kinds of vegetation canopies must be considered: sparse canopies and patchy canopies including bare soil strips. The mixed soil vegetation microwave emission is analyzed using a random continuous approach. The sparse canopy emission is efficiently described by considering the vegetation layer as homogeneous. Conversely, a simple soil-vegetation mixing equation must be used for the patchy canopies. The problem with retrieving the canopy temperature and the near-surface soil moisture is addressed. For every canopy, soil moisture retrieval is possible. Soil moisture maps are proposed. The canopy temperature can also be retrieved with good accuracy provided both vertical (v) and horizontal (h) polarizations are available. It is shown that the retrieved variables can be used to separate landscape units through a classification procedure.

  8. Is there a clear relationship between the Tropical Easterly Jet and Sahel rainfall?

    Science.gov (United States)

    Lemburg, Alexander; Bader, Jürgen; Claussen, Martin

    2017-04-01

    The West African Monsoon (WAM) is of great importance for many regions in sub-Saharan West Africa. The WAM is characterized by a pronounced seasonal wind shift initiated by thermodynamic contrasts between the land and ocean and is associated with precipitation changes. One feature of the WAM system is the Tropical Easterly Jet (TEJ), which is a summer-time upper-tropospheric (100-200hPa) easterly wind between 5° and 20°N. It originates in the South Asian Monsoon system over Bay of Bengal, extends westwards to Africa and decays over the tropical Atlantic. Previous studies found a positive correlation between Sahel rainfall and the strength of the West-African TEJ in the seasonal mean. It was suggested that a strong TEJ can enhance rainfall by increased upper-level divergence. However, it is also possible that a TEJ anomaly is a consequence of increased rainfall or that both are governed by an external quantity. A detailed study of possible physical mechanisms is still missing. In this study, we want to review the relationship between the TEJ and Sahel rainfall by a more in-depth statistical analysis. In contrast to previous studies, we include also high temporal resolution observations and reanalysis data which is necessary to better understand whether the jet is mainly forcing the rainfall or vice versa. Another focus of our analysis is whether a second independent/regional jet is developing over west Africa indicated by a second local maximum in the TEJ? Our results show substantial correlations between Sahel rainfall and TEJ strength on decadal time scales. On shorter time scales, the correlations become weaker and the relationship between the TEJ and Sahel rainfall is less clear. On intraseasonal time scales, it seems more that convection anomalies are leading changes in the TEJ by one or two days. The West African and the South Asian parts of the TEJ appear to be mainly independent on intraseasonal time scales. Pronounced wet years in the Sahel often show a

  9. Spatial distribution and temporal variability of Harmattan dust haze in sub-Sahel West Africa

    Science.gov (United States)

    Anuforom, Anthony C.

    The distributions of frequency of occurrence (FOO) of 'thick dust haze' (TDH) and of 'light dust haze' (LDH) with respect to latitude, longitude, elevation and distance from source during Harmattan season (from November to February) are investigated, using 30-year visibility data collected from 27 synoptic stations located in Nigeria between the West African Sahel and the coasts of Gulf of Guinea. This region lies along the Harmattan season trajectory of Saharan dust. Also investigated is the temporal variability of TDH and LDH on intra-seasonal and inter-annual timescales spanning three decades from 1971 to 2000. Dust haze distribution over the region is found to correlate with the four geographical variables to different extents, with latitude, distance from source and elevation showing strong correlations with both TDH and LDH. The investigation also shows that while FOO of TDH days increases with latitude (correlation coefficient, rlat,FOO_TDH=0.88), FOO of LDH days decreases with latitude over the region (correlation coefficient, rlat,FOO_LDH=-0.74). The correlation coefficients with longitude over the region are rlon,FOO_TDH=0.44 and rlon,FOO_LDH=-0.25, respectively, indicating weaker dependence of TDH and LDH on longitude. The average number of TDH days per month during the Harmattan season in the region ranges from about 0.5 in the humid coastal zone near the Gulf of Guinea in the south, to approximately 6 in the dry semi-arid zone near the West African Sahel. An empirical equation which shows that FOO of TDH increases exponentially with latitude over the region is derived. The FOO of TDH is found to be most variable in or near the Sahel zone and decreases southwards towards the Gulf of Guinea. The average of the standard deviations is 1.13 for the six northernmost synoptic stations and decreases to 0.51 over the six coastal and southernmost locations. In contrast, the FOO of LDH is most variable in the south (with standard deviation of 2.11 (over the six

  10. Hydrodynamic behaviour of crusted soils in the Sahel: a possible cause for runoff increase?

    Science.gov (United States)

    Malam Abdou, M.; Vandervaere, J.-P.; Bouzou Moussa, I.; Descroix, L.

    2012-04-01

    Crusted soils are in extension in the Sahel. As rainfall has decreased over the past decades (it is now increasing again in the central Sahel) and no significant change was observed in rainfall intensity and in its time and space distribution, it is supposed that land use management is the main cause for crusts cover increase. Fallow shortening, lack of manure, and land overexploitation (wood harvesting, overgrazing) are frequently cited as main factors of soil degradation. Based on field measurements in some small catchments of Western Niger, the hydrodynamics behaviour of the newly crusted soils of this area is described, mostly constituted by erosion crusts. A strong fall in soil saturated conductivity and in the active porosity as well as a rise in bulk density all lead to a quick onset of runoff production. Results are shown from field experiments in sedimentary and basement areas leading to similar conclusions. In both contexts, runoff plot production was measured at the rain event scale from 10-m2 parcels as well as at the catchment outlet. Soil saturated conductivity was reduced by one order of magnitude when crusting occurs, leading to a sharp runoff coefficient increase, from 4% in a weeded millet field and 10% in an old fallow to more than 60% in a erosion-crusted topsoil at the plot scale. At the experimental catchment scale, runoff coefficient has doubled in less than 20 years. In pure Sahelian basins, this resulted in endorheism breaching, and in a widespread river discharge increase. For some right bank tributaries of the Niger River, discharge is three times higher now than before the drought years, in spite of the remaining rainfall deficit. On the other hand, a general increase in flooding hazard frequency is observed in the whole Sahelian stripe. The role of surface crusts in the Sahel is discussed leading to the implementation of new experiments in the future.

  11. Impact of soil-vegetation-atmosphere interactions on the spatial rainfall distribution in the Central Sahel

    Directory of Open Access Journals (Sweden)

    Marcus Breil

    2017-10-01

    Full Text Available In a Regional Climate Model (RCM the interactions between the land surface and the atmosphere are described by a Soil-Vegetation-Atmosphere-Transfer Model (SVAT. In the presented study two SVATs of different complexity (TERRA-ML and VEG3D are coupled to the RCM COSMO-CLM (CCLM to investigate the impact of different representations of soil-vegetation-atmosphere interactions on the West African Monsoon (WAM system. In contrast to TERRA-ML, VEG3D comprises a more detailed description of the land-atmosphere coupling by including a vegetation layer in its structural design, changing the treatment of radiation and turbulent fluxes. With these two different model systems (CCLM-TERRA-ML and CCLM-VEG3D climate simulations are performed for West Africa and analyzed. The study reveals that the simulated spatial distribution of rainfall in the Sahel region is substantially affected by the chosen SVAT. Compared to CCLM-TERRA-ML, the application of CCLM-VEG3D results in higher near surface temperatures in the Sahel region during the rainy season. This implies a southward expansion of the Saharian heat-low. Consequently, the mean position of the African Easterly Jet (AEJ is also shifted to the south, leading to a southward displacement of tracks for Mesoscale Convective Systems (MCS, developing in connection with the AEJ. As a result, less precipitation is produced in the Sahel region, increasing the agreement with observations. These analyses indicate that soil-vegetation-atmosphere interactions impact the West African Monsoon system and highlight the benefit of using a more complex SVAT to simulate its dynamics.

  12. Advances in monitoring vegetation and land use dynamics in the Sahel

    DEFF Research Database (Denmark)

    Mbow, Cheikh; Fensholt, Rasmus; Nielsen, Thomas Theis

    2014-01-01

    to pastoralists, agro-pastoralists and forest-users, all depend on the availability of vegetation resources and are affected by fluctuations in the available vegetation resource. Vegetation dynamics are controlled by both natural and human factors, including climate change and variability, increased concentration......Vegetation dynamics of the West African Sahel has attracted great scientific interest over the last 40 years because of the dramatic inter-decadal variability observed in the resource base of the region directly impacting on the livelihoods of the West African population. From farmers...

  13. Environmental and Anthropogenic Degradation of Vegetation in the Sahel from 1982 to 2006

    Directory of Open Access Journals (Sweden)

    Khaldoun Rishmawi

    2016-11-01

    Full Text Available There is a great deal of debate on the extent, causes, and even the reality of land degradation in the Sahel. Investigations carried out before approximately 2000 using remote sensing data suggest widespread reductions in biological productivity, while studies extending beyond 2000 consistently reveal a net increase in vegetation production, strongly related to the recovery of rainfall following the extreme droughts of the 1970s and 1980s, and thus challenging the notion of widespread, long-term, subcontinental-scale degradation. Yet, the spatial variations in the rates of vegetation recovery are not fully explained by rainfall trends. It is hypothesized that, in addition to rainfall, other meteorological variables and human land use have contributed to vegetation dynamics. Throughout most of the Sahel, the interannual variability in growing season ΣNDVIgs (measured from satellites, used as a proxy of vegetation productivity was strongly related to rainfall, humidity, and temperature (mean r2 = 0.67, but with rainfall alone was weaker (mean r2 = 0.41. The mean and upper 95th quantile (UQ rates of change in ΣNDVIgs in response to climate were used to predict potential ΣNDVIgs—that is, the ΣNDVIgs expected in response to climate variability alone, excluding any anthropogenic effects. The differences between predicted and observed ΣNDVIgs were regressed against time to detect any long-term (positive or negative trends in vegetation productivity. Over most of the Sahel, the trends did not significantly depart from what is expected from the trends in meteorological variables. However, substantial and spatially contiguous areas (~8% of the total area of the Sahel were characterized by negative, and, in some areas, positive trends. To explore whether the negative trends were human-induced, they were compared with the available data of population density, land use, and land biophysical properties that are known to affect the susceptibility of

  14. An investigation of surface albedo variations during the recent sahel drought. [ats 3 observations

    Science.gov (United States)

    Norton, C. C.; Mosher, F. R.; Hinton, B.

    1978-01-01

    Applications Technology Satellite 3 green sensor data were used to measure surface reflectance variations in the Sahara/Sahel during the recent drought period; 1967 to 1974. The magnitude of the seasonal reflectance change is shown to be as much as 80% for years of normal precipitation and less than 50% for drought years. Year to year comparisons during both wet and dry seasons reveal the existence of a surface reflectance cycle coincident with the drought intensity. The relationship between the green reflectance and solar albedo is examined and estimated to be about 0.6 times the reflectance change observed by the green channel.

  15. An investigation of surface albedo variations during the recent Sahel drought

    Science.gov (United States)

    Norton, C. C.; Mosher, F. R.; Hinton, B.

    1979-01-01

    Applications Technology Satellite (ATS) 3 green sensor data are used to measure surface reflectance variations in the Sahara/Sahel during the recent drought period 1967-74. The magnitude of the seasonal reflectance change is shown to be as much as 80% for years of normal precipitation and less than 50% for drought years. Year-to-year comparisons during both wet and dry seasons reveal the existence of a surface reflectance cycle coincident with the drought intensity. The relationship between the green reflectance and solar albedo is examined and estimated to be about 0.6 times the reflectance change observed by the green channel.

  16. Climatic information of Western Sahel (1535-1793 AD) in original documentary sources

    Science.gov (United States)

    Millán, V.; Rodrigo, F. S.

    2014-09-01

    The Sahel is the semi-arid transition zone between arid Sahara and humid tropical Africa, extending approximately 10-20° N from Mauritania in the West to Sudan in the East. The African continent, one of the most vulnerable regions to climate change, is subject to frequent droughts and famine. One climate challenge research is to isolate those aspects of climate variability that are natural from those that are related to human influences. Therefore, the study of climatic conditions before mid-19th century, when anthropogenic influence was of minor importance, is very interesting. In this work the frequency of extreme events, such as droughts and floods, in Western Sahel from the 16th to 18th centuries is investigated using documentary data. Original manuscripts with historical chronicles from Walata and Nema (Mauritania), Timbuktu and Arawan (Mali), and Agadez (Niger) have been analyzed. Information on droughts, intense rainfall, storms and floods, as well as socioeconomic aspects (famines, pests, scarcity, prosperity) has been codified in an ordinal scale ranging from -2 (drought and famines) to +2 (floods) to obtain a numerical index of the annual rainfall in the region. Results show wet conditions in the 17th century, as well as dry conditions in the 18th century (interrupted by a short wet period in the 1730s decade).

  17. The effect of irrigated rice cropping on the alkalinity of two alkaline rice soils in the Sahel

    NARCIS (Netherlands)

    Asten, van P.J.A.; Zelfde, van 't J.A.; Zee, van der S.E.A.T.M.; Hammecker, C.

    2004-01-01

    Irrigated rice cropping is practiced to reclaim alkaline-sodic soils in many parts of the world. This practice is in apparent contrast with earlier studies in the Sahel, which suggests that irrigated rice cropping may lead to the formation of alkaline-sodic soils. Soil column experiments were done

  18. Future supply and demand of net primary production in the Sahel

    Science.gov (United States)

    Sallaba, Florian; Olin, Stefan; Engström, Kerstin; Abdi, Abdulhakim M.; Boke-Olén, Niklas; Lehsten, Veiko; Ardö, Jonas; Seaquist, Jonathan W.

    2017-12-01

    In the 21st century, climate change in combination with increasing demand, mainly from population growth, will exert greater pressure on the ecosystems of the Sahel to supply food and feed resources. The balance between supply and demand, defined as the annual biomass required for human consumption, serves as a key metric for quantifying basic resource shortfalls over broad regions.Here we apply an exploratory modelling framework to analyse the variations in the timing and geography of different NPP (net primary production) supply-demand scenarios, with distinct assumptions determining supply and demand, for the 21st century Sahel. We achieve this by coupling a simple NPP supply model forced with projections from four representative concentration pathways with a global, reduced-complexity demand model driven by socio-economic data and assumptions derived from five shared socio-economic pathways.For the scenario that deviates least from current socio-economic and climate trends, we find that per capita NPP begins to outstrip supply in the 2040s, while by 2050 half the countries in the Sahel experience NPP shortfalls. We also find that despite variations in the timing of the onset of NPP shortfalls, demand cannot consistently be met across the majority of scenarios. Moreover, large between-country variations are shown across the scenarios, in which by the year 2050 some countries consistently experience shortage or surplus, while others shift from surplus to shortage. At the local level (i.e. grid cell), hotspots of total NPP shortfall consistently occur in the same locations across all scenarios but vary in size and magnitude. These hotspots are linked to population density and high demand. For all scenarios, total simulated NPP supply doubles by 2050 but is outpaced by increasing demand due to a combination of population growth and the adoption of diets rich in animal products. Finally, variations in the timing of the onset and end of supply shortfalls stem from

  19. Farmers´ perceptions of climate change and agricultural adaptation strategies in rural Sahel

    DEFF Research Database (Denmark)

    Mertz, Ole; Mbow, Cheikh; Reenberg, Anette

    2009-01-01

    Farmers in the Sahel have always been facing climatic variability at intra- and inter-annual and decadal time scales. While coping and adaptation strategies have traditionally included crop diversification, mobility, livelihood diversification, and migration, singling out climate as a direct driver...... and occasional excess rainfall as the most destructive climate factors. Households attribute poor livestock health, reduced crop yields and a range of other problems to climate factors, especially wind. However, when questions on land use and livelihood change are not asked directly in a climate context...... in land use and livelihood strategies is driven by adaptation to a range of factors of which climate appears not to be the most important. Implications for policy-making on agricultural and economic development will be to focus on providing flexible options rather than specific solutions to uncertain...

  20. Climate variability and environmental stress in the Sudan-Sahel zone of West Africa

    DEFF Research Database (Denmark)

    Mertz, Ole; D'haen, Sarah Ann Lise; Maiga, Abdou

    2012-01-01

    , vegetation, and fauna, but more so in the 500–900 mm zones. Adaptation measures to counter environmental degradation included use of manure, reforestation, soil and water conservation, and protection of fauna and vegetation. The results raise concerns for future environmental management in the region......Environmental change in the Sudan-Sahel region of West Africa (SSWA) has been much debated since the droughts of the 1970s. In this article we assess climate variability and environmental stress in the region. Households in Senegal, Mali, Burkina Faso, Niger, and Nigeria were asked about climatic...... to household perceptions, observed rainfall patterns showed an increasing trend over the past 20 years. However, August rainfall declined, and could therefore potentially explain the contrasting negative household perceptions of rainfall trends. Most households reported degradation of soils, water resources...

  1. Solar-powered drip irrigation enhances food security in the Sudano–Sahel

    Science.gov (United States)

    Burney, Jennifer; Woltering, Lennart; Burke, Marshall; Naylor, Rosamond; Pasternak, Dov

    2010-01-01

    Meeting the food needs of Africa’s growing population over the next half-century will require technologies that significantly improve rural livelihoods at minimal environmental cost. These technologies will likely be distinct from those of the Green Revolution, which had relatively little impact in sub-Saharan Africa; consequently, few such interventions have been rigorously evaluated. This paper analyzes solar-powered drip irrigation as a strategy for enhancing food security in the rural Sudano–Sahel region of West Africa. Using a matched-pair comparison of villages in northern Benin (two treatment villages, two comparison villages), and household survey and field-level data through the first year of harvest in those villages, we find that solar-powered drip irrigation significantly augments both household income and nutritional intake, particularly during the dry season, and is cost effective compared to alternative technologies. PMID:20080616

  2. Rebuilding Resilience in the Sahel: Regreening in the Maradi and Zinder Regions of Niger

    Directory of Open Access Journals (Sweden)

    Jan Sendzimir

    2011-09-01

    Full Text Available The societies and ecosystems of the Nigerien Sahel appeared increasingly vulnerable to climatic and economic uncertainty in the late twentieth century. Severe episodes of drought and famine drove massive livestock losses and human migration and mortality. Soil erosion and tree loss reduced a woodland to a scrub steppe and fed a myth of the Sahara desert relentlessly advancing southward. Over the past two decades this myth has been shattered by the dramatic reforestation of more than 5 million hectares in the Maradi and Zinder Regions of Niger. No single actor, policy, or practice appears behind this successful regreening of the Sahel. Multiple actors, institutions and processes operated at different levels, times, and scales to initiate and sustain this reforestation trend. We used systems analysis to examine the patterns of interaction as biophysical, livelihood, and governance indicators changed relative to one another during forest decline and rebound. It appears that forest decline was reversed when critical interventions helped to shift the direction of reinforcing feedbacks, e.g., vicious cycles changed to virtuous ones. Reversals toward de-forestation or reforestation were preceded by institutional changes in governance, then livelihoods and eventually in the biophysical environment. Biophysical change sustained change in the other two domains until interventions introduced new ideas and institutions that slowed and then reversed the pattern of feedbacks. However, while society seems better at coping with economic or climatic shock or stress, the resilience of society and nature in the Maradi/Zinder region to global sources of uncertainty remains a pressing question in a society with one of the highest population growth rates on Earth.

  3. Woody vegetation die off and regeneration in response to rainfall variability in the west African Sahel

    Science.gov (United States)

    Brandt, Martin; Tappan, G. Gray; Aziz Diouf, Abdoul; Beye, Gora; Mbow, Cheikh; Fensholt, Rasmus

    2017-01-01

    The greening in the Senegalese Sahel has been linked to an increase in net primary productivity, with significant long-term trends being closely related to the woody strata. This study investigates woody plant growth and mortality within greening areas in the pastoral areas of Senegal, and how these dynamics are linked to species diversity, climate, soil and human management. We analyse woody cover dynamics by means of multi-temporal and multi-scale Earth Observation, satellite based rainfall and in situ data sets covering the period 1994 to 2015. We find that favourable conditions (forest reserves, low human population density, sufficient rainfall) led to a rapid growth of Combretaceae and Balanites aegyptiaca between 2000 and 2013 with an average increase of 4% woody cover. However, the increasing dominance and low drought resistance of drought prone species bears the risk of substantial woody cover losses following drought years. This was observed in 2014–2015, with a die off of Guiera senegalensis in most places of the study area. We show that woody cover and woody cover trends are closely related to mean annual rainfall, but no clear relationship with rainfall trends was found over the entire study period. The observed spatial and temporal variation contrasts with the simplified labels of “greening” or “degradation”. While in principal a low woody plant diversity negatively impacts regional resilience, the Sahelian system is showing signs of resilience at decadal time scales through widespread increases in woody cover and high regeneration rates after periodic droughts. We have reaffirmed that the woody cover in Sahel responds to its inherent climatic variability and does not follow a linear trend.

  4. Woody Vegetation Die off and Regeneration in Response to Rainfall Variability in the West African Sahel

    Directory of Open Access Journals (Sweden)

    Martin Brandt

    2017-01-01

    Full Text Available The greening in the Senegalese Sahel has been linked to an increase in net primary productivity, with significant long-term trends being closely related to the woody strata. This study investigates woody plant growth and mortality within greening areas in the pastoral areas of Senegal, and how these dynamics are linked to species diversity, climate, soil and human management. We analyse woody cover dynamics by means of multi-temporal and multi-scale Earth Observation, satellite based rainfall and in situ data sets covering the period 1994 to 2015. We find that favourable conditions (forest reserves, low human population density, sufficient rainfall led to a rapid growth of Combretaceae and Balanites aegyptiaca between 2000 and 2013 with an average increase of 4% woody cover. However, the increasing dominance and low drought resistance of drought prone species bears the risk of substantial woody cover losses following drought years. This was observed in 2014–2015, with a die off of Guiera senegalensis in most places of the study area. We show that woody cover and woody cover trends are closely related to mean annual rainfall, but no clear relationship with rainfall trends was found over the entire study period. The observed spatial and temporal variation contrasts with the simplified labels of “greening” or “degradation”. While in principal a low woody plant diversity negatively impacts regional resilience, the Sahelian system is showing signs of resilience at decadal time scales through widespread increases in woody cover and high regeneration rates after periodic droughts. We have reaffirmed that the woody cover in Sahel responds to its inherent climatic variability and does not follow a linear trend.

  5. Monitoring project impact on biomass increase in the context of the Great Green Wall for the Sahara and Sahel Initiative in Senegal

    OpenAIRE

    SCHUCKNECHT ANNE; MERONI MICHELE; REMBOLD Felix

    2016-01-01

    Land degradation and desertification represent a major threat to the population and ecosystems of (semi)-arid regions like the Sahel and the Sahara. In 2007, the African Union launched a pan-African programme, the Great Green Wall for the Sahara and the Sahel Initiative (GGWSSI) to reverse land degradation and desertification in the region, improve food security and support local people to adapt to climate change. Within the GGWSSI different kinds of projects have been implemented. In order t...

  6. Analysis of teleconnections between AVHRR-based sea surface temperature and vegetation productivity in the semi-arid Sahel

    DEFF Research Database (Denmark)

    Huber Gharib, Silvia; Fensholt, Rasmus

    2011-01-01

    Vegetation productivity across the Sahel is known to be affected by a variety of global sea surface temperature (SST) patterns. Often climate indices are used to relate Sahelian vegetation variability to large-scale ocean–atmosphere phenomena. However, previous research findings reporting...... on the Sahelian vegetation response to climate indices have been inconsistent and contradictory, which could partly be caused by the variations in spatial extent/definitions of climate indices and size of the region studied. The aim of this study was to analyze the linkage between climate indices, pixel......-wise spatio-temporal patterns of global sea surface temperature and the Sahelian vegetation dynamics for 1982–2007. We stratified the Sahel into five subregions to account for the longitudinal variability in rainfall. We found significant correlations between climate indices and the Normalized Difference...

  7. Geochemical and mineralogical evidence for Sahara and Sahel dust additions to Quaternary soils on Lanzarote, eastern Canary Islands, Spain

    Science.gov (United States)

    Muhs, D.R.; Budahn, J.; Skipp, G.; Prospero, J.M.; Patterson, D.; Bettis, E. Arthur

    2010-01-01

    Africa is the most important source of dust in the world today, and dust storms are frequent on the nearby Canary Islands. Previous workers have inferred that the Sahara is the most important source of dust to Canary Islands soils, with little contribution from the Sahel region. Soils overlying a late Quaternary basalt flow on Lanzarote, Canary Islands, contain, in addition to volcanic minerals, quartz and mica, exotic to the island's bedrock. Kaolinite in the soils also likely has an exotic origin. Trace-element geochemistry shows that the soils are derived from varying proportions of locally derived basalt and African dust. Major-element geochemistry, clay mineralogy and interpretation of satellite imagery suggest that dust additions to the Canary Islands come not only from the Sahara Desert, but also from the Sahel region. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

  8. The Crop Risk Zones Monitoring System for resilience to drought in the Sahel

    Science.gov (United States)

    Vignaroli, Patrizio; Rocchi, Leandro; De Filippis, Tiziana; Tarchiani, Vieri; Bacci, Maurizio; Toscano, Piero; Pasqui, Massimiliano; Rapisardi, Elena

    2016-04-01

    Food security is still one of the major concerns that Sahelian populations have to face. In the Sahel, agriculture is primarily based on rainfed crops and it is often structurally inadequate to manage the climatic variability. The predominantly rainfed cropping system of Sahel region is dependent on season quality on a year-to-year basis, and susceptible to weather extremes of droughts and extreme temperatures. Low water-storage capacity and high dependence on rainfed agriculture leave the agriculture sector even more vulnerable to climate risks. Crop yields may suffer significantly with either a late onset or early cessation of the rainy season, as well as with a high frequency of damaging dry spells. Early rains at the beginning of the season are frequently followed by dry spells which may last a week or longer. As the amount of water stored in the soil at this time of the year is negligible, early planted crops can suffer water shortage stresses during a prolonged dry spell. Therefore, the choice of the sowing date is of fundamental importance for farmers. The ability to estimate effectively the onset of the season and potentially dangerous dry spells becomes therefore vital for planning rainfed agriculture practices aiming to minimize risks and maximize yields. In this context, advices to farmers are key drivers for prevention allowing a better adaptation of traditional crop calendar to climatic variability. In the Sahel, particularly in CILSS (Permanent Interstates Committee for Drought Control in the Sahel) countries, national Early Warning System (EWS) for food security are underpinned by Multidisciplinary Working Groups (MWGs) lead by National Meteorological Services (NMS). The EWSs are mainly based on tools and models utilizing numeric forecasts and satellite data to outlook and monitor the growing season. This approach is focused on the early identification of risks and on the production of information within the prescribed time period for decision

  9. LONG-TERM MONITORING OF WATER DYNAMICS IN THE SAHEL REGION USING THE MULTI-SAR-SYSTEM

    OpenAIRE

    A. Bertram; A. Wendleder; Schmitt, A.; Huber, M.

    2016-01-01

    Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is of great importance, especially with regard to the spatio-temporal extend of wetlands and drylands. It can predict future trends and facilitate the...

  10. HAPEX-Sahel: a large-scale study of land-atmosphere interactions in the semi-arid tropics

    Directory of Open Access Journals (Sweden)

    J.-P. Goutorbe

    Full Text Available The Hydrologic Atmospheric Pilot EXperiment in the Sahel (HAPEX-Sahel was carried out in Niger, West Africa, during 1991 - 1992, with an intensive observation period (IOP in August - October 1992. It aims at improving the parameterization of land surface atmosphere interactions at the Global Circulation Model (GCM gridbox scale. The experiment combines remote sensing and ground based measurements with hydrological and meteorological modelling to develop aggregation techniques for use in large scale estimates of the hydrological and meteorological behaviour of large areas in the Sahel. The experimental strategy consisted of a period of intensive measurements during the transition period of the rainy to the dry season, backed up by a series of long term measurements in a 1° by 1° square in Niger. Three "supersites" were instrumented with a variety of hydrological and (micro meteorological equipment to provide detailed information on the surface energy exchange at the local scale. Boundary layer measurements and aircraft measurements were used to provide information at scales of 100 - 500 km2. All relevant remote sensing images were obtained for this period. This programme of measurements is now being analyzed and an extensive modelling programme is under way to aggregate the information at all scales up to the GCM grid box scale. The experimental strategy and some preliminary results of the IOP are described.

  11. Impact of aerosols on solar energy production - Scenarios from the Sahel Zone

    Science.gov (United States)

    Neher, Ina; Meilinger, Stefanie; Crewell, Susanne

    2017-04-01

    Solar energy is one option to serve the rising global energy demand with low environmental impact. Building an energy system with a considerable share of solar power requires long-term investment and a careful investigation of potential sites. Therefore, understanding the impacts from varying regionally and locally determined meteorological conditions on solar energy production will influence energy yield projections. Aerosols reduce global solar radiation due to absorption and scattering and therewith solar energy yields. Depending on aerosol size distribution they reduce the direct component of the solar radiation and modify the direction of the diffuse component compared to standard atmospheric conditions without aerosols. The aerosol size distribution and composition in the atmosphere is highly variable due to meteorological and land surface conditions. A quantitative assessment of aerosol effects on solar power yields and its relation to land use change is of particular interest for developing countries countries when analyzing the potential of local power production. This study aims to identify the effect of atmospheric aerosols in three different land use regimes, namely desert, urban/polluted and maritime on the tilted plane of photovoltaic energy modules. Here we focus on the Sahel zone, i.e. Niamey, Niger (13.5 N;2.1 E), located at the edge of the Sahara where also detailed measurements of the atmospheric state are available over the year 2006. Guided by observations a model chain is used to determine power yields. The atmospheric aerosol composition will be defined by using the Optical Properties of Aerosols and Clouds (OPAC) library. Direct and diffuse radiation (up- and downward component) are then calculated by the radiative transfer model libRadtran which allows to calculate the diffuse component of the radiance from different azimuth and zenith angles. Then the diffuse radiance will be analytically transformed to an east, south and west facing

  12. Farmers' Perceptions of Climate Change and Agricultural Adaptation Strategies in Rural Sahel

    Science.gov (United States)

    Mertz, Ole; Mbow, Cheikh; Reenberg, Anette; Diouf, Awa

    2009-05-01

    Farmers in the Sahel have always been facing climatic variability at intra- and inter-annual and decadal time scales. While coping and adaptation strategies have traditionally included crop diversification, mobility, livelihood diversification, and migration, singling out climate as a direct driver of changes is not so simple. Using focus group interviews and a household survey, this study analyzes the perceptions of climate change and the strategies for coping and adaptation by sedentary farmers in the savanna zone of central Senegal. Households are aware of climate variability and identify wind and occasional excess rainfall as the most destructive climate factors. Households attribute poor livestock health, reduced crop yields and a range of other problems to climate factors, especially wind. However, when questions on land use and livelihood change are not asked directly in a climate context, households and groups assign economic, political, and social rather than climate factors as the main reasons for change. It is concluded that the communities studied have a high awareness of climate issues, but climatic narratives are likely to influence responses when questions mention climate. Change in land use and livelihood strategies is driven by adaptation to a range of factors of which climate appears not to be the most important. Implications for policy-making on agricultural and economic development will be to focus on providing flexible options rather than specific solutions to uncertain climate.

  13. Links Between Terrorism, Organized Crime and Crime: The Case of the Sahel Region

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    Erik Alda

    2014-09-01

    Full Text Available Many observers hold that terrorist groups and transnational criminal networks share many of the same characteristics, methods and tactics. There are many examples cited to demonstrate these observations are not coincidental, but indicative of a trend: a trend that is a growing threat to the security interests of many nations. We propose that the intersection of criminal networks and terrorist organizations can be broadly grouped into three categories – coexistence (they coincidentally occupy and operate in the same geographic space at the same time, cooperation (they decide that their mutual interests are both served, or at not least severely threatened, by temporarily working together and convergence (each begins to engage in behavior(s that is/are more commonly associated with the other. The activities of these types of organizations in the Sahel region of Africa provide examples of all three categories of interactions. This perceived threat has prompted action and policy choices by a number of actors in the sub-region. But this assessment might not be accurate and may, in fact, be an attempt to force an extra-regional, inappropriate paradigm upon a specific situation and set of circumstances where they do not apply.

  14. The influence of land surface properties on Sahel climate. Part 1: Desertification

    Science.gov (United States)

    Xue, Yongkang; Shukla, Jagadish

    1993-01-01

    This is a general circulation model sensitivity study of the physical mechanisms of the effects of desertification on the Sahel drought. The model vegetation types were changed in the prescribed desertification area, which led to changes in the surface characteristics. The model was integrated for three months (June, July, August) with climatological surface conditions (control) and desertification conditions (anomaly) to examine the summer season response to the changed surface conditions. The control and anomaly experiments consisted of five pairs of integrations with different initial conditions and/or sea surface temperature boundary conditions. In the desertification experiment, the moisture flux convergence and rainfall were reduced in the test area and increased to the immediate south of this area. The simulated anomaly dipole pattern was similar to the observed African drought patterns in which the axis of the maximum rainfall shifts to the south. The circulation changes in the desertification experiment were consistent with those observed during sub-Saharan dry years. The tropical easterly jet was weaker and the African easterly jet was stronger than normal. Further, in agreement with the observations, the easterly wave disturbances were reduced in intensity but not in number. Descending motion dominated the desertification area. The surface energy budget and hydrological cycle were also changed substantially in the anomaly experiment.

  15. Farmers' perceptions of climate change and agricultural adaptation strategies in rural Sahel.

    Science.gov (United States)

    Mertz, Ole; Mbow, Cheikh; Reenberg, Anette; Diouf, Awa

    2009-05-01

    Farmers in the Sahel have always been facing climatic variability at intra- and inter-annual and decadal time scales. While coping and adaptation strategies have traditionally included crop diversification, mobility, livelihood diversification, and migration, singling out climate as a direct driver of changes is not so simple. Using focus group interviews and a household survey, this study analyzes the perceptions of climate change and the strategies for coping and adaptation by sedentary farmers in the savanna zone of central Senegal. Households are aware of climate variability and identify wind and occasional excess rainfall as the most destructive climate factors. Households attribute poor livestock health, reduced crop yields and a range of other problems to climate factors, especially wind. However, when questions on land use and livelihood change are not asked directly in a climate context, households and groups assign economic, political, and social rather than climate factors as the main reasons for change. It is concluded that the communities studied have a high awareness of climate issues, but climatic narratives are likely to influence responses when questions mention climate. Change in land use and livelihood strategies is driven by adaptation to a range of factors of which climate appears not to be the most important. Implications for policy-making on agricultural and economic development will be to focus on providing flexible options rather than specific solutions to uncertain climate.

  16. Management of protected areas in Sahel savannah ecoregion of Nigeria under the threat of desertification

    Directory of Open Access Journals (Sweden)

    BOROKINI Temitope Israel

    2013-12-01

    Full Text Available This study was conducted to assess the challenges facing 8 selected protected areas in the Sahel Savannah ecoregion and proffer solutions to these challenges in order to ensure conservation and sustainability of Nigeria’s biodiversity. Primary data were collected from randomly-selected 120 staffs using questionnaire administration from 8 Forest Reserves within Borno and Yobe states of Nigeria. A high level of encroachment of all the studied protected areas was observed, which ranged from deforestation, overgrazing, poaching to converting protected areas into farmlands. Other notable challenges include poor staffing, inadequate equipment and funding. The respondents further reported that majority of the defaulters were farmers and local people in the area, involved in such practices for their survival in the wake of harsher climate and desert encroachment in the region. This paper calls for a revision of the Government Policy on Forestry in Nigeria to allow the people own and plant forests, implementation of community based forest resources management, provision of environment and user-friendly solar powered cooking stoves and sustainable farming systems such as crop rotation, intercropping, sustainable irrigation, organic farming and agroforestry. In addition, sources of income for the locals need to be diversified, such as honey bee production.

  17. Geochemical variations in aeolian mineral particles from the Sahara-Sahel Dust Corridor.

    Science.gov (United States)

    Moreno, Teresa; Querol, Xavier; Castillo, Sonia; Alastuey, Andrés; Cuevas, Emilio; Herrmann, Ludger; Mounkaila, Mohammed; Elvira, Josep; Gibbons, Wes

    2006-10-01

    The Sahara-Sahel Dust Corridor runs from Chad to Mauritania and expels huge amounts of mineral aerosols into the Atlantic Ocean. Data on samples collected from Algeria, Chad, Niger, and Western Sahara illustrate how corridor dust mineralogy and chemistry relate to geological source and weathering/transport history. Dusts sourced directly from igneous and metamorphic massifs are geochemically immature, retaining soluble cations (e.g., K, Na, Rb, Sr) and accessory minerals containing HFSE (e.g., Zr, Hf, U, Th) and REE. In contrast, silicate dust chemistry in desert basins (e.g., Bodélé Depression) is influenced by a longer history of transport, physical winnowing (e.g., loss of Zr, Hf, Th), chemical leaching (e.g., loss of Na, K, Rb), and mixing with intrabasinal materials such as diatoms and evaporitic salts. Mineral aerosols blown along the corridor by the winter Harmattan winds mix these basinal and basement materials. Dusts blown into the corridor from sub-Saharan Africa during the summer monsoon source from deeply chemically weathered terrains and are therefore likely to be more kaolinitic and stripped of mobile elements (e.g., Na, K, Mg, Ca, LILE), but retain immobile and resistant elements (e.g., Zr, Hf, REE). Finally, dusts blown southwestwards into the corridor from along the Atlantic Coastal Basin will be enriched in carbonate from Mesozoic-Cenozoic marine limestones, depleted in Th, Nb, and Ta, and locally contaminated by uranium-bearing phosphate deposits.

  18. Improvement of the detection of desert dust over the Sahel using METEOSAT IR imagery

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    G. Vergé-Dépré

    2006-09-01

    Full Text Available Desert dust over the arid regions of Africa is detected using the Infrared Difference Dust Index (IDDI derived from the thermal infrared (TIR channel of METEOSAT. However, the comparison with photometric aerosol optical thickness (AOT of this dust index reveals some discrepancies. Using an instrumented site in Sahel where aerosol properties and meteorological conditions were monitored daily during the dry season, we performed radiative transfer computations with the MODTRAN 4.1 code to develop a method to improve the IDDI usefulness. We found that discrepancies between AOT and IDDI variations mostly come from changes in the surface temperature (Ts, which is an important parameter for radiative transfer computations in the TIR. We show that this temperature varies from day to day with the surface wind speed and during the course of the season with the solar elevation, and that it is possible, for the site considered, to correct Ts from these combined effect using a simple parameterization. We also observe that the dust layer itself has an impact on Ts by reducing the amount of solar radiation at the surface, and that this phenomenon can also be accounted for by adding an AOT-dependence to the above parameterization of Ts. We show that this parameterization allows improving the agreement between the IDDI and the photometric AOT.

  19. Improvement of the detection of desert dust over the Sahel using METEOSAT IR imagery

    Directory of Open Access Journals (Sweden)

    G. Vergé-Dépré

    2006-09-01

    Full Text Available Desert dust over the arid regions of Africa is detected using the Infrared Difference Dust Index (IDDI derived from the thermal infrared (TIR channel of METEOSAT. However, the comparison with photometric aerosol optical thickness (AOT of this dust index reveals some discrepancies. Using an instrumented site in Sahel where aerosol properties and meteorological conditions were monitored daily during the dry season, we performed radiative transfer computations with the MODTRAN 4.1 code to develop a method to improve the IDDI usefulness. We found that discrepancies between AOT and IDDI variations mostly come from changes in the surface temperature (Ts, which is an important parameter for radiative transfer computations in the TIR. We show that this temperature varies from day to day with the surface wind speed and during the course of the season with the solar elevation, and that it is possible, for the site considered, to correct Ts from these combined effect using a simple parameterization. We also observe that the dust layer itself has an impact on Ts by reducing the amount of solar radiation at the surface, and that this phenomenon can also be accounted for by adding an AOT-dependence to the above parameterization of Ts. We show that this parameterization allows improving the agreement between the IDDI and the photometric AOT.

  20. Long-Term Monitoring of Water Dynamics in the Sahel Region Using the Multi-Sar

    Science.gov (United States)

    Bertram, A.; Wendleder, A.; Schmitt, A.; Huber, M.

    2016-06-01

    Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is of great importance, especially with regard to the spatio-temporal extend of wetlands and drylands. It can predict future trends and facilitate the development of adequate management strategies. Lake Tabalak, a Ramsar wetland of international importance, is one of the most significant ponds in Niger and a refuge for waterbirds. Nevertheless, human population growth increased the pressure on this ecosystem, which is now degrading for all uses. The main objective of the study is a long-term monitoring of the Lake Tabalak's water dynamics to delineate permanent and seasonal water bodies, using weather- and daytime-independent multi-sensor and multi-temporal Synthetic Aperture Radar (SAR) data available for the study area. Data of the following sensors from 1993 until 2016 are used: Sentinel-1A, TerraSARX, ALOS PALSAR-1/2, Envisat ASAR, RADARSAT-1/2, and ERS-1/2. All SAR data are processed with the Multi-SAR-System, unifying the different characteristics of all above mentioned sensors in terms of geometric, radiometric and polarimetric resolution to a consistent format. The polarimetric representation in Kennaugh elements allows fusing single-polarized data acquired by older sensors with multi-polarized data acquired by current sensors. The TANH-normalization guarantees a consistent and therefore comparable description in a closed data range in terms of radiometry. The geometric aspect is solved by projecting all images to an earth-fixed coordinate system correcting the brightness by the help of the incidence angle. The elevation model used in the geocoding step is the novel global model produced by the TanDEM-X satellite

  1. [Demography and development in the Sahel. The major challenges of the 21st century are already there].

    Science.gov (United States)

    Ignegongba, K

    1992-07-01

    In the early 1990s, Sahelian governments resolved to carry out direct demographic activities. Many issues essential for development and, in some cases, for the satisfaction of basic needs revolve around education, health, food, environment, employment, and urbanization. The total primary school attendance rate for the nine Sahelian countries is about 40%. The failure of the education system is translated into almost systematic unemployment of graduates and very great ineffectiveness. Education should be adapted to economic conditions and development so as to actually lead to production. For example, it should train persons for agricultural and livestock production. Governments should mobilize necessary resources to improve the quality of education. The current poor health indicators require Sahelian governments in the future to invest and underwrite much to keep up with the rising rate of population growth. Otherwise, young children will always pay the heaviest debt. The impact of AIDS on health resources will risk turning attention away from other fatal diseases. Soil degradation and reduced rainfall make the Sahel depend on the importation of food products. The Sahel must find ways to reduce this dependence or it will perish while waiting for international generosity. Agricultural and pastoral modes of production are expanding the desert. Sahelians must again find harmony between themselves and their milieu. Youth cannot find jobs. Governments and businesses cut staff to meet conditions of structural adjustment programs. When one worker supports more than 10 persons, the employment problem favors poverty and rising corruption. Soil degradation and low incomes in rural areas, which offer no hope of social promotion, are the chief causes of rural-urban migration in the Sahel. The capacity of Sahelian countries to support improvement in rural areas remains a key to many problems, including food self-sufficiency.

  2. Selection for earlier flowering crop associated with climatic variations in the Sahel.

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    Yves Vigouroux

    Full Text Available Climate changes will have an impact on food production and will require costly adaptive responses. Adapting to a changing environment will be particularly challenging in sub-Saharan Africa where climate change is expected to have a major impact. However, one important phenomenon that is often overlooked and is poorly documented is the ability of agro-systems to rapidly adapt to environmental variations. Such an adaptation could proceed by the adoption of new varieties or by the adaptation of varieties to a changing environment. In this study, we analyzed these two processes in one of the driest agro-ecosystems in Africa, the Sahel. We performed a detailed study in Niger where pearl millet is the main crop and covers 65% of the cultivated area. To assess how the agro-system is responding to recent recurrent drought, we analyzed samples of pearl millet landraces collected in the same villages in 1976 and 2003 throughout the entire cultivated area of Niger. We studied phenological and morphological differences in the 1976 and 2003 collections by comparing them over three cropping seasons in a common garden experiment. We found no major changes in the main cultivated varieties or in their genetic diversity. However, we observed a significant shift in adaptive traits. Compared to the 1976 samples, samples collected in 2003 displayed a shorter lifecycle, and a reduction in plant and spike size. We also found that an early flowering allele at the PHYC locus increased in frequency between 1976 and 2003. The increase exceeded the effect of drift and sampling, suggesting a direct effect of selection for earliness on this gene. We conclude that recurrent drought can lead to selection for earlier flowering in a major Sahelian crop. Surprisingly, these results suggest that diffusion of crop varieties is not the main driver of short term adaptation to climatic variation.

  3. Socioeconomic potential of carbon sequestration through agroforestry in the West African Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Alavalpati, J.R.R. [School of Forest Resources and Conservation, University of Florida, Gainesville, FL (United States); Nair, P.K.R. [School of Forest Resources and Conservation, University of Florida, Gainesville, FL (United States); Takimoto A. [School of Forest Resources and Conservation, University of Florida, Gainesville, FL (United States)

    2008-08-15

    The recognition of agroforestry as a greenhouse-gas mitigation strategy under the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) offers an opportunity to agroforestry practitioners to benefit from the global carbon (C) credit market. Our knowledge on this important topic from the semiarid regions such as the West African Sahel (WAS) is, however, very limited. In order to fill this gap, this study was undertaken in the Segou region of Mali (annual temperature, 29{sup o}C; annual rainfall, 300-700 mm in 60 to 90 days), focusing on two improved agroforestry systems (live fence and fodder bank) along with traditional parkland agroforestry systems of the region. A cost-benefit analysis was conducted to assess the economic profitability and risks associated with the systems considering them as 25-year projects and their potential for participation in C credit market. The traditional systems had high C stock in their biomass and soil, but little potential for sequestering additional C; on the other hand, the improved systems had low C stock, but high sequestration potential. For the standard size live fence (291 m) and fodder bank (0.25 ha) projects, the estimated net present values (NPV) were $96.0 and $158.8 without C credit sale, and $109.9 and $179.3 with C sale, respectively. From the C sale perspective, live fence seemed less risky and more profitable than fodder bank. Carbon credit sale is likely to contribute to economic development of the subsistence farmers in the WAS.

  4. Serum cortisol of Sahel goats following rumenotomy with assorted anaesthetics and sutures

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    Abubakar Mshelia Saidu

    2016-06-01

    Full Text Available The utmost need for pragmatic combination of surgical sutures and local anaesthetic that would evoke minimal post-surgical stress response and allow uncomplicated healing is essential for successful surgeries. Fifteen Sahel goats were randomly allocated into three groups A, B and C to quantitatively assay (ELISA serum cortisol profiles following rumenotomy, as markers of surgical stress. Diazepam at 0.2 mg/kg was administered intravenously to groups A and B with subsequent lidocaine HCl and bupivacaine inverted-L block respectively. Group C did not receive any treatment. Chromic catgut (CCG and polyglycolic acid (PGA sutures were used for rumen and abdominal muscles closure for groups A and B respectively and nylon for skin closure. Blood samples were taken at post anaesthetic induction (PAI and post-surgery at 0, 5, 8, 24, 48 and 72 h. The Group A goats expressed serum cortisol that was significantly high 52.76 ± 6.12 ng/mL at 5 h post-surgery. At 8 h post-surgery serum cortisol for both groups A (72.53 ± 3.79 ng/mL and B (61.59 ± 3.90 ng/mL were at their peak. Serum cortisol levels compared to the baseline data were significantly different (P  0.05. Cortisol responses unambiguously indicate that diazepam-bupivacaine induce less stress than Diazepam-lidocaine, hence a preferred anesthesia. Moreover, polyglycolic acid sutures are associated with less inflammatory reaction than chromic catgut.

  5. Climate or Land Use?—Attribution of Changes in River Flooding in the Sahel Zone

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    Valentin Aich

    2015-06-01

    Full Text Available This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950–2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood

  6. Land cover change and plants diversity in the Sahel: A case study from northern Burkina Faso

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    Abel Kadeba

    2015-04-01

    Full Text Available Understanding land cover degradation patterns and the effects of geomorphological units on phytodiversity is important for guiding management decisions and restoration strategies in the Sahelian vulnerables zones. This paper describes land cover degradation by combining Landsat TM image analysis and field data measurements in the Gourouol catchment of the Sahelian zone of Burkina Faso. Erdas Imagine 9.2 and Arc-GIS.10 were applied. The change patterns were obtained by superposing land cover maps for 1992 and 2010. The field data were collected by the mean of inventories according to the Braun-Blanquet phytosociological relevés methods. Plot sizes were 50 m x 20 m for woody species and 10 m x 10 m for herbaceous species. Six land cover types were identified and mapped: cultivated lands, bared lands, lowlands, which all spatially increased; and shrub-steppes, grasslands and water bodies, which all spatially decreased. The dynamic patterns based on the geomorphological units were non-degraded lowlands, stable sand dunes and degraded glacis. High plant diversity was found in lowlands, whereas low diversity occurred in glacis. A significant dissimilarity was observed between communities. The Shannon diversity indices in plant communities were approximately close to ln(species richness. The Pielou indices were close to 1, indicating a species fairly good distribution. Our results showed a variation of land cover over time and the effects of geomorphological units on phytodiversity. Furthermore, this variation helps oppose land degradation in the Sahel.

  7. Local knowledge and perception of biological soil crusts by land users in the Sahel (Niger)

    Science.gov (United States)

    J-M Ambouta, K.; Hassan Souley, B.; Malam Issa, O.; Rajot, J. L.; Mohamadou, A.

    2012-04-01

    Local knowledge, i.e. knowledge based on accumulation of observations is of great interest for many scientific fields as it can help for identification, evaluation and selection of relevant indicators and furthermore for progress through conservation goals. This study aimed at gathering and understanding the local knowledge and perception of biological soil crusts (BSC) by users of land, pastoralists that cross the Sahel and sedentary farmers. The methodological approach is based on a semi-direct surveys conducted on a north-south rainfall gradient (350 to 650 mm/year) including agricultural- and pastoral-dominated areas in western Niger. Denomination, formation processes, occurrence, distribution and role of biological soil crusts are among the major issues of the inquiry. The results of the surveys showed that BSC are mainly identified by the names of "Bankwado" and "Korobanda", respectively in hausa and zarma langages, what means "toad back". Other denominations varying according to region, ethnic groups and users are used. They are all related to the aspects, colors and behaviour of BSC with regard wetting and drying cycle. From the point of view of users depressed areas and land lied fallow are favourable places for the occurrence of BSC, while cultivation and observed changes in rainfall regimes represent negative factors. The formation processes of BSC are mainly related to the occurrence and the impact of rain and wind on soil surface. Their roles in protecting soil against degradation or as an indicator of soil fertility were recognised by at least 83% of farmers and breeders. This study reveals significant aspects of BSC already validated by scientific knowledge. Integrating the two forms of knowledge will help to define relevant indicators of soil surface dynamics and to perform practices to minimize farming and grazing impacts on BSCs.

  8. Deriving albedo maps for HAPEX-Sahel from ASAS data using kernel-driven BRDF models

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    P. Lewis

    1999-01-01

    Full Text Available This paper describes the application and testing of a method for deriving spatial estimates of albedo from multi-angle remote sensing data. Linear kernel-driven models of surface bi-directional reflectance have been inverted against high spatial resolution multi-angular, multi- spectral airborne data of the principal cover types within the HAPEX-Sahel study site in Niger, West Africa. The airborne data are obtained from the NASA Airborne Solid-state Imaging Spectrometer (ASAS instrument, flown in Niger in September and October 1992. The maps of model parameters produced are used to estimate integrated reflectance properties related to spectral albedo. Broadband albedo has been estimated from this by weighting the spectral albedo for each pixel within the map as a function of the appropriate spectral solar irradiance and proportion of direct and diffuse illumination. Partial validation of the results was performed by comparing ASAS reflectance and derived directional-hemispherical reflectance with simulations of a millet canopy made with a complex geometric canopy reflectance model, the Botanical Plant Modelling System (BPMS. Both were found to agree well in magnitude. Broadband albedo values derived from the ASAS data were compared with ground-based (point sample albedo measurements and found to agree extremely well. These results indicate that the linear kernel-driven modelling approach, which is to be used operationally to produce global 16 day, 1 km albedo maps from forthcoming NASA Earth Observing System spaceborne data, is both sound and practical for the estimation of angle-integrated spectral reflectance quantities related to albedo. Results for broadband albedo are dependent on spectral sampling and on obtaining the correct spectral weigthings.

  9. Arthropod diversity and assemblage structure response to deforestation and desertification in the Sahel of western Senegal

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    Brandon J. Lingbeek

    2017-07-01

    Full Text Available Drylands are highly vulnerable to desertification and among the most endangered ecosystems. To understand how biodiversity responds to environmental degradation in these fragile ecosystems, we examined whether arthropod, beetle, spider and ant diversity and assemblage structure differed (1 between seasons, (2 among locations (3 between protected areas of tropical dry forest and adjacent communal lands suffering from desertification, as well as (4 how vegetation impacts assemblage structures. We established 12 plots spaced homogenously throughout each protected area and the adjacent communal land at three locations: Beersheba, Bandia and Ngazobil. Within each plot, we measured canopy closure, vegetation height, percent cover of bare ground, leaf litter, grasses and forbs and collected arthropods using pitfall traps during the 2014 dry (May and rainy (September seasons. We collected 123,705 arthropods representing 733 morphospecies, 10,849 beetles representing 216 morphospecies, 4969 spiders representing 91 morphospecies and 59,183 ants representing 45 morphospecies. Results showed greater arthropod and beetle diversities (P = 0.002–0.040 in the rainy season, no difference in diversity among locations for any taxonomic group and a difference (P ≤ 0.001 in diversity for all taxa between protected areas and communal lands. Assemblage structures of all taxa responded (P = 0.001 to vegetation characteristics, differed (P = 0.015–0.045 between seasons and, with a few exceptions, locations and fragments. Our results illustrate the importance of a multi-taxa approach in understanding biodiversity response to anthropogenic disturbances as well as the value of protected areas in preserving biodiversity of the Sahel.

  10. Evaluating water controls on vegetation growth in the semi-arid sahel using field and earth observation data

    DEFF Research Database (Denmark)

    Abdi, Abdulhakim M.; Boke-Olen, Niklas; Tenenbaum, David E.

    2017-01-01

    Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP) have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we...... identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and evaluate the relationships between field data and Earth observation-derived spectral products for up-scaling GPP. We find that plant-available water and vapor pressure deficit together control the GPP...

  11. Relation between seasonally detrended shortwave infrared reflectance data and land surface moisture in semi-arid Sahel

    DEFF Research Database (Denmark)

    Olsen, Jørgen Lundegaard; Ceccato, Pietro; Proud, Simon Richard

    2013-01-01

    . In this study we explored the potential of using reflectance data in the Red, Near Infrared (NIR), and Shortwave Infrared (SWIR) spectral regions for detecting short term variations in land surface moisture in the Sahel, by analyzing data from three test sites and observations from the geostationary Meteosat......In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue...

  12. Evaluating Water Controls on Vegetation Growth in the Semi-Arid Sahel Using Field and Earth Observation Data

    Directory of Open Access Journals (Sweden)

    Abdulhakim M. Abdi

    2017-03-01

    Full Text Available Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and evaluate the relationships between field data and Earth observation-derived spectral products for up-scaling GPP. We find that plant-available water and vapor pressure deficit together control the GPP of Sahelian vegetation through their impact on the greening and browning phases. Our results show that a multiple linear regression (MLR GPP model that combines the enhanced vegetation index, land surface temperature, and the short-wave infrared reflectance (Band 7, 2105–2155 nm of the moderate-resolution imaging spectroradiometer satellite sensor was able to explain between 88% and 96% of the variability of eddy covariance flux tower GPP at three Sahelian sites (overall = 89%. The MLR GPP model presented here is potentially scalable at a relatively high spatial and temporal resolution. Given the scarcity of field data on CO2 fluxes in the Sahel, this scalability is important due to the low number of flux towers in the region.

  13. Multiple and differentiated contributions to the male gene pool of pastoral and farmer populations of the African Sahel.

    Science.gov (United States)

    Bučková, Jana; Cerný, Viktor; Novelletto, Andrea

    2013-05-01

    The African Sahel is conducive to studies of divergence/admixture genetic events as a result of its population history being so closely related with past climatic changes. Today, it is a place of the co-existence of two differing food-producing subsistence systems, i.e., that of sedentary farmers and nomadic pastoralists, whose populations have likely been formed from several dispersed indigenous hunter-gatherer groups. Using new methodology, we show here that the male gene pool of the extant populations of the African Sahel harbors signatures of multiple and differentiated contributions from different genetic sources. We also show that even if the Fulani pastoralists and their neighboring farmers share high frequencies of four Y chromosome subhaplogroups of E, they have drawn on molecularly differentiated subgroups at different times. These findings, based on combinations of SNP and STR polymorphisms, add to our previous knowledge and highlight the role of differences in the demographic history and displacements of the Sahelian populations as a major factor in the segregation of the Y chromosome lineages in Africa. Interestingly, within the Fulani pastoralist population as a whole, a differentiation of the groups from Niger is characterized by their high presence of R1b-M343 and E1b1b1-M35. Moreover, the R1b-M343 is represented in our dataset exclusively in the Fulani group and our analyses infer a north-to-south African migration route during a recent past. Copyright © 2013 Wiley Periodicals, Inc.

  14. The 2007 flood in the Sahel: causes, characteristics and its presentation in the media and FEWS NET

    Directory of Open Access Journals (Sweden)

    C. Samimi

    2012-02-01

    Full Text Available During the rainy season in 2007, reports about exceptional rains and floodings in the Sahel were published in the media, especially in August and September. Institutions and organizations like the World Food Programme (WFP and FEWS NET put the events on the agenda and released alerts and requested help. The partly controversial picture was that most of the Sahel faced a crisis caused by widespread floodings. Our study shows that the rainy season in 2007 was exceptional with regard to rainfall amount and return periods. In many areas the event had a return period between 1 and 50 yr with high spatial heterogeneity, with the exception of the Upper Volta basin, which yielded return periods of up to 1200 yr. Despite the strong rainfall, the interpretation of satellite images show that the floods were mainly confined to lakes and river beds. However, the study also proves the difficulties in assessing the meteorological processes and the demarcation of flooded areas in satellite images without ground truthing. These facts and the somewhat vague and controversial reports in the media and FEWS NET demonstrate that it is crucial to thoroughly analyze such events at a regional and local scale involving the local population.

  15. Simulation of the Impact of Climate Variability on Malaria Transmission in the Sahel

    Science.gov (United States)

    Bomblies, A.; Eltahir, E.; Duchemin, J.

    2007-12-01

    A coupled hydrology and entomology model for simulation of malaria transmission and malaria transmitting mosquito population dynamics is presented. Model development and validation is done using field data and observations collected at Banizoumbou and Zindarou, Niger spanning three wet seasons, from 2005 through 2007. The primary model objective is the accurate determination of climate variability effects on village scale malaria transmission. Malaria transmission dependence on climate variables is highly nonlinear and complex. Temperature and humidity affect mosquito longevity, temperature controls parasite development rates in the mosquito as well as subadult mosquito development rates, and precipitation determines the formation and persistence of adequate breeding pools. Moreover, unsaturated zone hydrology influences overland flow, and climate controlled evapotranspiration rates and root zone uptake therefore also influence breeding pool formation. High resolution distributed hydrologic simulation allows representation of the small-scale ephemeral pools that constitute the primary habitat of Anopheles gambiae mosquitoes, the dominant malaria vectors in the Niger Sahel. Remotely sensed soil type, vegetation type, and microtopography rasters are used to assign the distributed parameter fields for simulation of the land surface hydrologic response to precipitation and runoff generation. Predicted runoff from each cell flows overland and into topographic depressions, with explicit representation of infiltration and evapotranspiration. The model's entomology component interacts with simulated pools. Subadult (aquatic stage) mosquito breeding is simulated in the pools, and water temperature dependent stage advancement rates regulate adult mosquito emergence into the model domain. Once emerged, adult mosquitoes are tracked as independent individual agents that interact with their immediate environment. Attributes relevant to malaria transmission such as gonotrophic

  16. The project RUSSADE: geoethic education to face environmental problems in the Sahel

    Science.gov (United States)

    Ferrero, Elena; Semita, Carlo

    2016-04-01

    The hard environmental and climatic conditions in Sahel countries affect life choices of younger generations, whose number continues to increase especially in large Sahelian cities, with increasing levels of discomfort and lack of adequate education and governance. To improve job opportunities and consequently the quality of life at all levels of the population, it is important to guarantee a better access to basic natural resources, such as soil, water, food. At the same time it is essential to spread awareness and knowledge of the vulnerability and of the risks that threaten natural resources, both for natural processes and for the interaction with human not sustainable activities. For this purpose, a Master course has been achieved in the project RUSSADE (Réseau des Universités Sahéliennes pour la Sécurité Alimentaire et la Durabilité Environnementale - www.russade.eu), funded in the ACP-EU Cooperation Programme in higher education (EDULINK II). The Master course includes teaching modules dedicated to these issues and takes care of their integration with other modules in the technical and application fields of the rural development. For instance, the objectives of the teaching module "Land and natural resources management" provide for the transmission of skills to diagnose types of soil degradation risks, to guide options for protection, conservation and soil restoration and to identify the components of integrated soil fertility management in particular African contexts (Subunit "Land management"); to choose appropriate methods of management and exploitation of water resources (defining the limits in the use of water resources) (Subunit "Water supply"); to propose alternative solutions concerning conventional energy resources, to know and promote the various possibilities of solar and other renewable energies production (Subunit "Using solar and other renewable energies"). Some teaching modules introduce and discuss risks related to inadequate waste

  17. Rain-Use-Efficiency: What it Tells us about the Conflicting Sahel Greening and Sahelian Paradox

    Directory of Open Access Journals (Sweden)

    Cécile Dardel

    2014-04-01

    Full Text Available Rain Use Efficiency (RUE, defined as Aboveground Net Primary Production (ANPP divided by rainfall, is increasingly used to diagnose land degradation. Yet, the outcome of RUE monitoring has been much debated since opposite results were found about land degradation in the Sahel region. The debate is fueled by methodological issues, especially when using satellite remote sensing data to estimate ANPP, and by differences in the ecological interpretation. An alternative method which solves part of these issues relies on the residuals of ANPP regressed against rainfall (“ANPP residuals”. In this paper, we use long-term field observations of herbaceous vegetation mass collected in the Gourma region in Mali together with remote sensing data (GIMMS-3g Normalized Difference Vegetation Index to estimate ANPP, RUE, and the ANPP residuals, over the period 1984–2010. The residuals as well as RUE do not reveal any trend over time over the Gourma region, implying that vegetation is resilient over that period, when data are aggregated at the Gourma scale. We find no conflict between field-derived and satellite-derived results in terms of trends. The nature (linearity of the ANPP/rainfall relationship is investigated and is found to have no impact on the RUE and residuals interpretation. However, at odds with a stable RUE, an increased run-off coefficient has been observed in the area over the same period, pointing towards land degradation. The divergence of these two indicators of ecosystem resilience (stable RUE and land degradation (increasing run-off coefficient is referred to as the “second Sahelian paradox”. When shallow soils and deep soils are examined separately, high resilience is diagnosed on the deep soil sites. However, some of the shallow soils show signs of degradation, being characterized by decreasing vegetation cover and increasing run-off coefficient. Such results show that contrasted changes may co-exist within a region where a

  18. CO2 fluxes at leaf and canopy scale in millet, fallow and tiger bush vegetation at the HAPEX-Sahel southern super-site.

    NARCIS (Netherlands)

    Levy, P.E.; Moncrieff, J.B.; Massheder, J.M.; Jarvis, P.G.; Scott, S.L.; Brouwer, J.

    1997-01-01

    Measurements of canopy and leaf scale CO2 flux from the three sub-sites at the HAPEX-Sahel Southern supersite are presented. These are analysed in relation to biological and environmental variables. At leaf scale, the flux is most strongly influenced by photosynthetic photon flux density (PPFD) and

  19. Analysis for dry and wet years with the WIMISA model of tree-crop competition for wind break systems in the Sahel

    NARCIS (Netherlands)

    Mayus, M.; Keulen, van H.; Stroosnijder, L.

    1999-01-01

    A modelling approach was chosen for analyzing the effects of competition between windbreaks and crops for soil water and radiation in the Sahel. The model has a high spatial and temporal resolution to account for the heterogeneity in a windbreak-cropping system. The model was parameterised for

  20. Household possession, use and non-use of treated or untreated mosquito nets in two ecologically diverse regions of Nigeria – Niger Delta and Sahel Savannah

    Directory of Open Access Journals (Sweden)

    Otsemobor Peju

    2009-02-01

    Full Text Available Abstract Background Current use of treated mosquito nets for the prevention of malaria falls short of what is expected in sub-Saharan Africa (SSA, though research within the continent has indicated that the use of these commodities can reduce malaria morbidity by 50% and malaria mortality by 20%. Governments in sub-Sahara Africa are investing substantially in scaling-up treated mosquito net coverage for impact. However, certain significant factors still prevent the use of the treated mosquito nets, even among those who possess them. This survey examines household ownership as well as use and non-use of treated mosquito nets in Sahel Savannah and Niger Delta regions of Nigeria. Methodology This survey employed cross-sectional survey to collect data from households on coverage and use of mosquito nets, whether treated or not. Fever episodes in previous two weeks among children under the age of five were also recorded. The study took place in August 1 – 14 2007, just five months after the March distribution of treated mosquito nets, coinciding with the second raining period of the year and a time of high malaria transmission during the wet season. EPI INFO version 2003 was used in data analysis. Results The survey covered 439 households with 2,521 persons including 739 under-fives, 585 women in reproductive age and 78 pregnant women in Niger Delta Region and Sahel Savannah Region. Of the 439 HHs, 232 had any mosquito nets. Significantly higher proportion of households in the Niger Delta Region had any treated or untreated mosquito nets than those in the Sahel Savannah Region. In the Niger Delta Region, the proportion of under-fives that had slept under treated nets the night before the survey exceeded those that slept under treated nets in the Sahel Savannah Region. Children under the age of five years in the Niger Delta Region were four times more likely to sleep under treated nets than those in the Sahel Savannah Region. Conclusion This study

  1. Effects of dexamethasone on progesterone and estrogen profiles and uterine progesterone receptor localization during pregnancy in Sahel goat in Semi-Arid region

    Directory of Open Access Journals (Sweden)

    Dauda Yahi

    2017-05-01

    Full Text Available Abstract Background Despite the widespread use of dexamethasone in veterinary and human medicine, it is reported to cause some severe pregnancy related side effects like abortion in some animals. The mechanism of the response is not clear but seems to be related to interspecies and/or breed difference in response which may involve alterations in the concentrations of some reproductive hormones. Methods Twenty Sahel goats comprising 18 does and 2 bucks were used for this study. Pregnancies were achieved by natural mating after synchronization. Repeated dexamethasone injections were given at 0.25 mg/kg body weight. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested at days 28 and day 78 of gestation through caesarean section for immunohistochemical analysis using 3 pregnant does randomly selected from each group at each instant. Data were expressed as Means ± Standard Deviations and analyzed using statistical soft ware package, GraphPad Instant, version 3.0 (2003 and progesterone receptor (PR were scored semi-quantitatively. Results Dexamethasone treatments had no significant (p > 0.05 effect on progesterone and estrogen concentrations in pregnant Sahel goats but up regulated PR from 2+ to 3+ in second trimester. Conclusion As dexamethasone adverse effect on placenta is an established fact, the lack of effect on progesterone level in this study may be due to the fact that unlike other species whose progesterone production during pregnancy is placenta – dependent, in goats is corpus luteum - dependent. Consequently dexamethasone adverse effect on placenta reported in literatures did not influence progesterone levels during pregnancy in Sahel goat. The up regulation of progesterone receptor (PR in Sahel goat gravid uterus is a beneficial effects and that dexamethasone can safely be used in corpus luteum – dependent progesterone secreting pregnant animal species like Sahel goat and camel. Therefore

  2. Effects of dexamethasone on progesterone and estrogen profiles and uterine progesterone receptor localization during pregnancy in Sahel goat in Semi-Arid region.

    Science.gov (United States)

    Yahi, Dauda; Ojo, Nicholas Adetayo; Mshelia, Gideon Dauda

    2017-01-01

    Despite the widespread use of dexamethasone in veterinary and human medicine, it is reported to cause some severe pregnancy related side effects like abortion in some animals. The mechanism of the response is not clear but seems to be related to interspecies and/or breed difference in response which may involve alterations in the concentrations of some reproductive hormones. Twenty Sahel goats comprising 18 does and 2 bucks were used for this study. Pregnancies were achieved by natural mating after synchronization. Repeated dexamethasone injections were given at 0.25 mg/kg body weight. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested at days 28 and day 78 of gestation through caesarean section for immunohistochemical analysis using 3 pregnant does randomly selected from each group at each instant. Data were expressed as Means ± Standard Deviations and analyzed using statistical soft ware package, GraphPad Instant, version 3.0 (2003) and progesterone receptor (PR) were scored semi-quantitatively. Dexamethasone treatments had no significant (p > 0.05) effect on progesterone and estrogen concentrations in pregnant Sahel goats but up regulated PR from 2+ to 3+ in second trimester. As dexamethasone adverse effect on placenta is an established fact, the lack of effect on progesterone level in this study may be due to the fact that unlike other species whose progesterone production during pregnancy is placenta - dependent, in goats is corpus luteum - dependent. Consequently dexamethasone adverse effect on placenta reported in literatures did not influence progesterone levels during pregnancy in Sahel goat. The up regulation of progesterone receptor (PR) in Sahel goat gravid uterus is a beneficial effects and that dexamethasone can safely be used in corpus luteum - dependent progesterone secreting pregnant animal species like Sahel goat and camel. Therefore source of progesterone secretions during pregnancy should be considered

  3. Contrasting conditions of surface water balance in wet years and dry years as a possible land surface-atmosphere feedback mechanism in the West African Sahel

    Science.gov (United States)

    Lare, A. R.; Nicholson, S. E.

    1994-01-01

    The climate of West Africa, in particular the Sahel, is characterized by multiyear persistence of anomalously wet or dry conditions. Its Southern Hemisphere counterpart, the Kalahari, lacks the persistence that is evident in the Sahel even though both regions are subject to similar large-scale forcing. It has been suggested that land surface-atmosphere feedback contributes to this persistence and to the severity of drought. In this study, surface energy and water balance are quantified for nine stations along a latitudinal transect that extends from the Sahara to the Guinea coast. In the wetter regions of West Africa, the difference between wet and dry years is primarily reflected in the magnitude of runoff. For the Sahel and drier locations, evapotranspiration and soil moisture are more sensitive to rainfall anomalies. The increase in evapotranspiration, and hence latent heating, over the Sahel in wet years alters the thermal structure and gradients of the overlying atmosphere and thus the strength of the African easterly jet (AEJ) at 700 mb. The difference between dry and wet Augusts corresponds to a decrease in magnitude of the AEJ at 15 deg N on the order of 2.6 m/s, which is consistent with previous studies of observed winds. Spatial patterns were also developed for surface water balance parameters for both West Africa and southern Africa. Over southern Africa, the patterns are not as spatially homogeneous as those over West Africa and are lower in magnitude, thus supporting the suggestion that the persistence of rainfall anomalies in the Sahel might be due, at least in part, to land-atmosphere feedback, and that the absence of such persistence in the Kalahari is a consequence of less significant changes in surface water and energy balance.

  4. A Record of Early to Middle Holocene Hydroclimate Variability from the West African Sahel

    Science.gov (United States)

    McIntosh, R.; Douglas, P. M.; Warren, C.; Meyers, S. R.; Coutros, P.; Park, D. P.

    2011-12-01

    The African Humid Period (ca. 14.8 to 5.5 ka) is an interval of wet climates across northwest Africa, with evidence for widespread lake basins and savannah vegetation in areas that are now desert. There are few high-resolution continental records of hydrologic variability during the African humid period however. In particular, it remains uncertain how periods of north Atlantic climate variability were expressed in northwest Africa. We present results from a 5.4 meter sediment core from Lake Fati in northern Mali (16.29° N, 3.71° W), which represents the first lake sediment core from the western Sahel. The Lake Fati core contains a continuous record of lake mud from 10.43 to 4.66 kyr BP. Centimeter scale XRF scanning indicates strong covariation between iron, calcium, manganese and phosphorous abundance due to enrichment of these elements during periods of enhanced deposition of authigenic siderite. Preliminary oxygen isotope measurements indicate that authigenic siderite δ18O values are positively correlated with Fe counts, suggesting that siderite deposition increased during drier periods with greater evaporation of lake waters. These drying events occurred on decadal to centennial time scales, with higher-frequency variability during the early Holocene. Peaks in zirconium and titanium abundance coincide with some of the inferred dry periods, suggesting that deposition of aeolian silt coincided with periods of increased evaporation of lake water. A roughly 30 year interval of sand deposition at ~8.33 kyr BP suggests major drying and activation of aeolian sand deposition. This abrupt climate change could be related to the 8.2 ka event in the North Atlantic; further efforts to refine the sediment core age model will constrain the relationship of this rapid drying to abrupt climate change in the North Atlantic. Aluminum and silicon counts co-vary for much of the lake Fati record, and are related to input of terrigenous sediment, primarily during seasonal flooding

  5. África al sur del Sahara: conflictos y degradación ambiental en el Sahel

    Directory of Open Access Journals (Sweden)

    Stella Maris Shmite

    2015-08-01

    Full Text Available The Sahel is a region located south of the Sahara Desert that is affected by a combination of problems, including droughts, soil degradation, demographic pressure, malnutrition, poverty, migration, conflicts, and refugees, among others. In this region, environmental changes strongly impact sociocultural, political and economic dimensions. These changes also act as multipliers of social tensions and stimulate political instability. The goal of this article is to identify these problems and analyze environmental variables to address the territorial context. This study seeks to interpret a range of sources, such as cartographical data, statistics and academic publications, that may allow for not only the complex network of persisting conflicts but also emerging conflicts in this cross-border African region to be comprehensively visualized and understood.

  6. Using earth observation-based dry season NDVI trends for assessment of changes in tree cover in the Sahel

    DEFF Research Database (Denmark)

    Horion, Stéphanie Marie Anne F; Fensholt, Rasmus; Tagesson, Håkan Torbern

    2014-01-01

    -based trends were generally not confirmed at the local scale based on selected study cases, partly caused by a temporal mismatch between data sets (i.e. different periods of analysis). Analysis of desert area NDVImin trends indicates less stable values for VGT and GIMMS data as compared with MODIS....... This suggests that trends in dry season NDVImin derived from VGT and GIMMS should be used with caution as an indicator for changes in tree cover, whereas the MODIS data stream shows a better potential for tree-cover change analysis in the Sahel......., with a potential reduction in tree cover having important implications for the Sahelian population. Large-scale EO-based evaluation of changes in Sahelian tree cover is assessed by analysing long-term trends in dry season minimum normalized difference vegetation index (NDVImin) derived from three different...

  7. [Intestinal parasitic diseases in an urban environment in Sahel. A study in a district of Niamey, Niger].

    Science.gov (United States)

    Julvez, J; Badé, M A; Lamotte, M; Campagne, G; Garba, A; Gragnic, G; Bui, A; Kehren, S; Cluzel, F; Chippaux, J P

    1998-01-01

    Health and environment in Niamey, a capital in Sahel, are particularly linked owing to population growth, promiscuity and large pollution induced by human and animal excreta. One district, located in the centre of the town, was surveyed for drinking water quality (ammoniac and bacterial count) and use, as well as for the prevalence of parasites through both a random sample (fixed tools with methiolate-iodine-formaldehyde) and a systematic one (scotch-test). Water consumption was 16.5 litres/day/man from fresh water supplies (87%) and private wells (13%). Ammoniac measures were low in the wells but high in running water (pool and river). It was the same for faecal coliform bacteria. These results give evidence of biotope faecal pollution. The random sample (322 persons, male/female sex ratio 0,85, average age 20,6 years) showed a 42.1% parasitic prevalence. Amoeba was the most frequent parasite (53.6%); and Giardia (14.9%) was the most frequent pathogenic parasite. In the second sample (161 children under 10 years), 24.2% were carriers of oxyuris. This large intestinal parasitism, without any change in connection with previous data in Niger, points to an important fecal contamination of the people more by the way of "dirty hands" than consumption of drinking water. The parasites observed have a short biological cycle, not necessitating long-term maturation in the environment. Those whose ova or larvae must complete their cycle outside have no possibility of surviving in Sahel, thanks to the beneficial effect of sunlight (heat and ultraviolet light). The inhabitants of this district seem to have adapted to intestinal parasitism. But the occurrence of malnutrition linked to a new drought could lead rapidly to a very serious adverse result.

  8. The Fight Against Extremism in the Trans-Sahel: The Utilization of Soft Power by the Department of State to Establish, Develop, and Strengthen Potential Partnerships

    Science.gov (United States)

    2016-02-16

    soft power “plus” by the Department of State is the operation of its International Law Enforcement Academies (ILEA). “The mission of the ILEAs are...training and soft power “plus” influence provided by the ATA program. In conjunction with the State Departments law enforcement efforts, the TSCTP...Page 1 of 22 Professional Studies Paper The Fight Against Extremism in the Trans-Sahel: The Utilization of Soft Power by the

  9. Modelling the effect of soil moisture and organic matter degradation on biogenic NO emissions from soils in Sahel rangeland (Mali

    Directory of Open Access Journals (Sweden)

    C. Delon

    2015-06-01

    Full Text Available This work is an attempt to provide seasonal variation of biogenic NO emission fluxes in a Sahelian rangeland in Mali (Agoufou, 15.34° N, 1.48° W for years 2004, 2005, 2006, 2007 and 2008. Indeed, NO is one of the most important precursors for tropospheric ozone, and previous studies have shown that arid areas potentially display significant NO emissions (due to both biotic and abiotic processes. Previous campaigns in the Sahel suggest that the contribution of this region in emitting NO is no longer considered as negligible. However, very few data are available in this region, therefore this study focuses on model development. The link between NO production in the soil and NO release to the atmosphere is investigated in this modelling study, by taking into account vegetation litter production and degradation, microbial processes in the soil, emission fluxes, and environmental variables influencing these processes, using a coupled vegetation–litter decomposition–emission model. This model includes the Sahelian Transpiration Evaporation and Productivity (STEP model for the simulation of herbaceous, tree leaf and faecal masses, the GENDEC model (GENeral DEComposition for the simulation of the buried litter decomposition and microbial dynamics, and the NO emission model (NOFlux for the simulation of the NO release to the atmosphere. Physical parameters (soil moisture and temperature, wind speed, sand percentage which affect substrate diffusion and oxygen supply in the soil and influence the microbial activity, and biogeochemical parameters (pH and fertilization rate related to N content are necessary to simulate the NO flux. The reliability of the simulated parameters is checked, in order to assess the robustness of the simulated NO flux. Simulated yearly average of NO flux ranges from 2.09 to 3.04 ng(N m−2 s−1 (0.66 to 0.96 kg(N ha−1 yr−1, and wet season average ranges from 3.36 to 5.48 ng(N m−2 s−1 (1.06 to 1.73 kg(N ha−1 yr−1

  10. África al sur del Sahara: conflictos y degradación ambiental en el Sahel

    Directory of Open Access Journals (Sweden)

    Stella Maris Shmite

    2015-01-01

    Full Text Available El Sahel es una región ubicada al sur del desierto del Sahara, donde se conjugan múltiples problemáticas: sequías, degradación de suelos, presión demográfica, desnutrición, pobreza, migraciones, conflictos, refugiados, entre otras. Los cambios ambientales provocan un fuerte impacto en las dimensiones socioculturales, políticas y económicas, actúan como multiplicadores de las tensiones sociales y estimulan la inestabilidad política. El objetivo de este artículo es identificar estas problemáticas y analizar las variables ambientales, con el fin de abordar el contexto territorial. La investigación se orientó hacia la interpretación de diversas fuentes como cartografía, estadísticas y publicaciones académicas, que abren la posibilidad de mirar y comprender de manera integral la compleja trama de conflictos que perduran, así como los emergentes en este territorio transfronterizo de África.

  11. Investigation on the Fiber Biometry and Chemical Compounds of Bast and without Bast Stalk of Cotton Stalk Sahel Variety

    Directory of Open Access Journals (Sweden)

    A.Reza Seraian

    2012-01-01

    Full Text Available In order to determine the fiber dimensions, physical and chemical properties of the bast and without bast stalk of Sahel-Variety of cotton stalk, required samples were prepared and studied. The results showed that fiber and lumen diameter and  cell wall thickness of  without bast stalk fibers were greater than those of bast fibers, while bast fibers were longer. Thus, this fibers can be classified as short and medium length fibers respectively.Data showed that the Length/ Diameter ratio and Runkle ratio of the bast fibers were greater than those of without bast stalk fibers, and flexibility coefficient in without bast stalk fibers was greater. Stalk with higher diameter had less bast proportion.Oven-dried density and swelling and shrinkage values of thicker stalks were greater than those of thinner ones, but apparent and basic densities,as well as porosity in thinner stalks were higher. Chemical Properties of bast and without bast stalk were respectively as follow: cellulose 39.27% and 48.3%,lignin 23.93% and 21.89% ,extractives 6.06% and 3.23% , ash content 6.36% and 1.85% ,one percent sodium hydroxide solubility 48.35% and 21.275% and hot water solubility19.48% and 9.68%.These indicate that without bast stalk fibers are more suitable than bast fibers for pulp production, but bast fibers are preferred in terms of fiber length.

  12. LONG-TERM MONITORING OF WATER DYNAMICS IN THE SAHEL REGION USING THE MULTI-SAR-SYSTEM

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    A. Bertram

    2016-06-01

    Full Text Available Fresh water is a scarce resource in the West-African Sahel region, seasonally influenced by droughts and floods. Particularly in terms of climate change, the importance of wetlands increases for flora, fauna, human population, agriculture, livestock and fishery. Hence, access to open water is a key factor. Long-term monitoring of water dynamics is of great importance, especially with regard to the spatio-temporal extend of wetlands and drylands. It can predict future trends and facilitate the development of adequate management strategies. Lake Tabalak, a Ramsar wetland of international importance, is one of the most significant ponds in Niger and a refuge for waterbirds. Nevertheless, human population growth increased the pressure on this ecosystem, which is now degrading for all uses. The main objective of the study is a long-term monitoring of the Lake Tabalak’s water dynamics to delineate permanent and seasonal water bodies, using weather- and daytime-independent multi-sensor and multi-temporal Synthetic Aperture Radar (SAR data available for the study area. Data of the following sensors from 1993 until 2016 are used: Sentinel-1A, TerraSARX, ALOS PALSAR-1/2, Envisat ASAR, RADARSAT-1/2, and ERS-1/2. All SAR data are processed with the Multi-SAR-System, unifying the different characteristics of all above mentioned sensors in terms of geometric, radiometric and polarimetric resolution to a consistent format. The polarimetric representation in Kennaugh elements allows fusing single-polarized data acquired by older sensors with multi-polarized data acquired by current sensors. The TANH-normalization guarantees a consistent and therefore comparable description in a closed data range in terms of radiometry. The geometric aspect is solved by projecting all images to an earth-fixed coordinate system correcting the brightness by the help of the incidence angle. The elevation model used in the geocoding step is the novel global model produced by the

  13. Local Vegetation Trends in the Sahel of Mali and Senegal Using Long Time Series FAPAR Satellite Products and Field Measurement (1982–2010

    Directory of Open Access Journals (Sweden)

    Martin Brandt

    2014-03-01

    Full Text Available Local vegetation trends in the Sahel of Mali and Senegal from Geoland Version 1 (GEOV1 (5 km and the third generation Global Inventory Modeling and Mapping Studies (GIMMS3g (8 km Fraction of Absorbed Photosynthetically Active Radiation (FAPAR time series are studied over 29 years. For validation and interpretation of observed greenness trends, two methods are applied: (1 a qualitative approach using in-depth knowledge of the study areas and (2 a quantitative approach by time series of biomass observations and rainfall data. Significant greening trends from 1982 to 2010 are consistently observed in both GEOV1 and GIMMS3g FAPAR datasets. Annual rainfall increased significantly during the observed time period, explaining large parts of FAPAR variations at a regional scale. Locally, GEOV1 data reveals a heterogeneous pattern of vegetation change, which is confirmed by long-term ground data and site visits. The spatial variability in the observed vegetation trends in the Sahel area are mainly caused by varying tree- and land-cover, which are controlled by human impact, soil and drought resilience. A large proportion of the positive trends are caused by the increment in leaf biomass of woody species that has almost doubled since the 1980s due to a tree cover regeneration after a dry-period. This confirms the re-greening of the Sahel, however, degradation is also present and sometimes obscured by greening. GEOV1 as compared to GIMMS3g made it possible to better characterize the spatial pattern of trends and identify the degraded areas in the study region.

  14. Satellite-based observations of rain-induced NOx emissions from soils around Lake Chad in the Sahel

    Science.gov (United States)

    Zörner, Jan; Penning de Vries, Marloes; Dörner, Steffen; Sihler, Holger; Beirle, Steffen; Wagner, Thomas

    2017-04-01

    Rain-induced emission pulses of NOx (≡ NO + NO2) from soils have been observed in many semi-arid regions over the world. They are induced by the first precipitation of the wet season and are mainly caused by the sudden re-activation of microbes in the soil releasing reactive nitrogen. In this study, a single intense event of pulsed NOx emissions from soils around Lake Chad is investigated. This is achieved by analysing daily tropospheric NO2 vertical column densities (VCDs) as observed by the satellite-based OMI instrument together with other satellite and model data on precipitation, lightning, fire and wind. The study region of Lake Chad and its ecosystems are indispensable to life in the Sahel region. Climate variability and unsustainable water utilization, however, caused a drastic decrease in the lakes' surface area which, in turn, lead to extensive land cover changes converting former lake area to shrub land and fertile farm land. The results indicate that the region of Lake Chad does not only show consistent enhancements in average NO2 VCDs in the early months of the wet season compared to its surrounding desert but also exhibits particularly strong NOx emissions shortly after a single large-scale precipitation event in June 2007. NO2 VCDs measured 14 hours after this precipitation event show strong enhancements (2.5*1015 molecules cm-2) compared to the seasonal background VCDs and, moreover, represent the highest detected NO2 VCDs of the entire year. Detailed analysis of potential contributors to the observed NO2 VCDs strongly indicate that fire, lightning and retrieval artefacts cannot explain the NO2 pulse. The estimated emission flux from the soil, calculated based on mass balance, amounts to about 32.3 ng N m-2 s-1, which corresponds to about 65 tonnes of nitrogen released to the atmosphere within one day.

  15. On the range of future Sahel precipitation projections and the selection of a sub-sample of CMIP5 models for impact studies

    Science.gov (United States)

    Monerie, Paul-Arthur; Sanchez-Gomez, Emilia; Boé, Julien

    2017-04-01

    The future evolution of the West African Monsoon is studied by analyzing 32 CMIP5 models under the rcp8.5 emission scenario. A hierarchical clustering method based on the simulated pattern of precipitation changes is used to classify the models. Four groups, which do not agree on the simple sign of future Sahel precipitation change, are obtained. We find that the inter-group differences are mainly associated with the large spread in (1) temperature increase over the Sahara and North Atlantic and in (2) the strengthening of low and mid-level winds. A wetter Sahel is associated with a strong increase in temperature over the Sahara (>6 °C), a northward shift of the monsoon system and a weakening of the African Easterly jet. A dryer Sahel is associated with subsidence anomalies, a strengthening of the 600 hPa wind speed, and a weaker warming over the Northern Hemisphere. Moreover, the western (central) Sahel is projected to become dryer (wetter) during the first months (last months) of the rainy season in a majority of models. We propose several methods to select a sub-sample of models that captures both the ensemble mean pattern and/or the spread of precipitation changes from the full ensemble. This methodology is useful in all the situations for which it is not possible to deal with a large ensemble of models, and in particular most impact studies. We show that no relationship exists between the climatological mean biases in precipitation and temperature and the future changes in the monsoon intensity. This indicates that the mean bias is therefore not a reliable metric for the model selection. For this reason, we propose several methodologies, based on the projected precipitation changes: The "diversity" method, which consists in the selection of one model from each group is the most appropriate to capture the spread in precipitation change. The "pattern selection" method, which consists in the selection of models in a single group allows to select models for the

  16. Analysis of Awareness and Adaptation to Climate Change among Farmers in the Sahel Savannah Agro-ecological Zone of Borno State, Nigeria

    OpenAIRE

    Idrisa, Y. L.; Ogunbameru, B. O.; Ibrahim, A.A.; Bawa, D. B.

    2012-01-01

    This study examined the awareness and adaptation to climate change among farmers in the Sahel Savannah agro-ecological zone of Borno State, Nigeria. Data for the study were collected from 225 respondents selected through the Multi-stage sampling technique. A socio-economic profile of the respondents indicated that 48.89% were above 45 years of age and majority (78.23%) had educational qualifications below the secondary school level. The study also revealed that a majority (79.12%) of the resp...

  17. Use of TOMS data to quantify the respective impacts of Sahel drought and North Atlantic Oscillation on African dust sources and export over the last two decades

    Science.gov (United States)

    Moulin, C.; Chiapello, I.

    2003-04-01

    Atmospheric wind-blown dust from arid regions of Africa affects the radiative budget over Africa and tropical Atlantic (Li et al., 1996) and likely modifies the regional climate (Alpert et al., 1998). Former studies based on surface measurements (Middleton, 1985; Prospero and Nees, 1986) have shown that emission and transport of African dust have been dramatically increased during the two severe Sahel droughts in early 1970's and 1980's. More recently, Meteosat images have revealed the impact of meteorological conditions, defined by the North Atlantic Oscillation (NAO), on the inter-annual variability of dust export over the tropical North Atlantic (Moulin et al., 1996). Here we use the TOMS Absorbing Aerosol Index archive to monitor dust optical thicknesses over Atlantic and Africa during the last 20 years and to relate its variability to changes in NAO and Sahel drought. The drought impact on dust sources in semi-arid regions of western Sahel is shown to be the primary cause of variability in dust export to the tropical North Atlantic during both winter and summer. The NAO impact on African dust export cannot however be neglected, mainly in summer when it controls the intensity of the largest dust sources in arid regions. Li, X., Maring, H., Savoie, D., Voss, K., and Prospero, J.M., Dominance of mineral dust in aerosol light scattering in the North Atlantic Trade Winds. Nature, 380, 416-419 (1996). Alpert, P., Kaufman, Y.J., Shay-El, Y., Tanré, D., Da Silva, A., Schubert, S., and Joseph, Y.H., Quantification of dust-forced heating of the lower troposphere. Nature, 395, 367-370 (1998). Prospero, J.M. and Nees, R.T., Impact of the North African drought and El-Nino on the mineral dust in the Barbados trade winds. Nature, 320, 735-738 (1986). Middleton, N. J. Effect of drought on dust production in the Sahel. Nature, 316, 431-434 (1985). Moulin, C., Lambert, C.E., Dulac, F., and Dayan, U., Control of atmospheric export of dust from North Africa by the North Atlantic

  18. Soil Management Practices to Improve Nutrient-use Efficiencies and Reduce Risk in Millet-based Cropping Systems in the Sahel

    Directory of Open Access Journals (Sweden)

    Koala, S.

    2003-01-01

    Full Text Available Low soil fertility and moisture deficit are among the main constraints to sustainable crop yields in the Sahel. A study therefore, was conducted at the ICRISAT Sahelian Center, Sadore in Niger to test the hypothesis that integrated soil husbandry practices consisting of manure, fertilizer and crop residues in rotational cropping systems use organic and mineral fertilizes efficiently, thereby resulting in higher yields and reduced risk. Results from an analysis of variance showed that choice of cropping systems explained more than 50% of overall variability in millet and cowpea grain yields. Among the cropping systems, rotation gave higher yields than sole crop and intercropping systems and increased millet yield by 46% without fertilizer. Rainfall-use efficiency and partial factor productivity of fertilizer were similarly higher in rotations than in millet monoculture system. Returns from cowpea grown in cowpea-millet rotation without fertilizer and the medium rates of fertilizers (4 kg P.ha-1 + 15 kg N.ha-1 were found to be most profitable in terms of high returns and low risk, principally because of a higher price of cowpea than millet. The study recommends crop diversification, either in the form of rotations or relay intercropping systems for the Sahel as an insurance against total crop failure.

  19. Colonisation humaine et développement sur une frontière écologique. Le Despoblado, le Sahel du Piura-Pérou Septentrional

    Directory of Open Access Journals (Sweden)

    1991-01-01

    Full Text Available Le despoblado de Piura est une formation végétale mixte arborée et herbacée, un sahel qui, malgré des précipitations très irrégulières, associe plusieurs ressources complémentaires. Elles ont été diversement utilisées au fur et à mesure de l’intervention de nouvelles techniques. - Cueillette des racines et fruits de la pampa d’interfluves. - Arboriculture sur huerta d’inférofluse à l’amont, et cultures saisonnières sur les lits intermittents et petit élevage caprin sur l’algarrobal des interfluves. - Cultures commerciales d’irrigation permanente par dérivation des eaux de la sierra et maintien d’un petit élevage de despoblado. Trois étapes de la colonisation du Piura. Mais la dernière, si elle permet de supporter une forte densité paysanne, ne peut éviter les conséquences des fortes pluies exceptionnelles. COLONIZACIÓN HUMANA Y DESARROLLO SOBRE FRONTERA ECOLÓGICA. EL DESPOBLADO, EL SAHEL DE PIURA, NORTE-PERÚ. El despoblado de Piura es una formación vegetal mixta, arboleda y savana ocasional, un sahel que, a pesar de lluvias muy irregulares, combina varios recursos complementarios. Ésos fueron aprovechados distintamente a medida de la intervención de nuevas técnicas. - Recolección de raíces y frutas en las pampas de las planicies secas - Arboricultura en las huertas de las cabezas de conos torrenciales y cultura estacional sobre los cauces inundables de las quebradas, aguas abajo, y cría de cabras y asnos en el algarrobal de las pampas - Cultivos comerciales de riego permanente por desvío de aguas de los grandes ríos de la sierra, y permanencia de la ganadería de caprinos sobre las pampas del despoblado. Son tres etapas del asentamiento humano. Pero la última, si tiene la ventaja de soportar grandes densidades campesinas, no puede arrastrar el peligro de las lluvias excepcionales. HUMAN SETTLING AND DEVELOPMENT ON AN ECOLOGIC FRONTIERS. THE DESPOBLADO, THE SAHEL OF SEPTENTRIONAL PIURA-PERU. A Piura

  20. Satellite-based drought monitoring in the Sahel: Evaluation of two global physically-based evapotranspiration algorithms

    Science.gov (United States)

    Garcia, Monica; Mu, Qiaozhen; Ceccato, Pietro; Ardö, Jonas; Mougin, Eric; Kergoat, Laurent; Timouk, Franck; Sandholt, Inge; Fisher, Joshua

    2013-04-01

    Regional estimates of daily evapotranspiration and surface fluxes in water-scarce and climatic vulnerable regions are critical for improving agricultural and hydrological information as well as our understanding of land surface-atmosphere interactions. The final aim of this study is to evaluate two global operational evapotranspiration algorithms in the Sahelian grasslands of Africa, where in-situ data are scarce, relying on satellite products at 1 km spatial resolution with no field calibration or in-situ variables. Two process-based models were applied to estimate surface fluxes including evapotranspiration (ET): the global MODIS evapotranspiration algorithm (MOD16), based on a three source Penman-Monteith approach; and a version of the PT-JPL model, based on a three source Priestley-Taylor model with an apparent thermal inertia module to estimate soil moisture. Both models were forced using climatic reanalyses data from two sources: MERRA GMAO (NASA reanalysis GEOS-5) and NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research). Additionally, to assess if errors were due to algorithm assumptions or with the quality of input data in-situ climatic tower data were used to compare with results from reanalyses. All model results were compared with eddy covariance data from two field sites in Mali and Sudan spanning a total period of 5 years. Preliminary results showed a better performance of both algorithms using in-situ climatic data, with a superior performance of the PT-JPL model despite a low bias relative to the measured ET. Climatic forcing with MERRA provided better results than using NCEP data. Aggregation of results from daily to 8-day time scale decreased errors significantly. The PT-JPL model version with a thermal inertia approach to estimate soil moisture offers great potential for regionalization in regions where the main limitation to evapotranspiration is soil moisture, such as the Sahel as no field

  1. Comparison of Leaf Traits and Branching Patterns between Acacia tortilis (Forsk.) Hayne subsp. raddiana (Savi) Brenan, Balanites aegyptiaca (L.) Del. and Ziziphus mauritiana Lam. Seedlings Originated from the Sahel

    NARCIS (Netherlands)

    Ngaryo, Fidèle; Badiatte, Ampa Kande; Goudiaby, Venceslas; Akpo, L.E.

    2016-01-01

    Aims: The aim of this study was to compare the leaf traits and branching patterns between Acacia tortilis, Balanites aegyptiaca and Ziziphus mauritiana seedlings, three species occurring in the same range in the Sahel, a semi-arid tropical area of Africa.
    Study Design: Seeds used in this

  2. A 60-year reconstructed high-resolution local meteorological data set in Central Sahel (1950-2009): evaluation, analysis and application to land surface modelling

    Science.gov (United States)

    Leauthaud, Crystele; Cappelaere, Bernard; Demarty, Jérôme; Guichard, Françoise; Velluet, Cécile; Kergoat, Laurent; Vischel, Théo; Grippa, Manuela; Mouhaimouni, Mohammed; Bouzou Moussa, Ibrahim; Mainassara, Ibrahim; Sultan, Benjamin

    2017-04-01

    The Sahel has experienced strong climate variability in the past decades. Understanding its implications for natural and cultivated ecosystems is pivotal in a context of high population growth and mainly agriculture-based livelihoods. However, efforts to model processes at the land-atmosphere interface are hindered, particularly when the multi-decadal timescale is targeted, as climatic data are scarce, largely incomplete and often unreliable. This study presents the generation of a long-term, high-temporal resolution, multivariate local climatic data set for Niamey, Central Sahel. The continuous series spans the period 1950-2009 at a 30-min timescale and includes ground station-based meteorological variables (precipitation, air temperature, relative and specific humidity, air pressure, wind speed, downwelling long- and short-wave radiation) as well as process-modelled surface fluxes (upwelling long- and short-wave radiation,latent, sensible and soil heat fluxes and surface temperature). A combination of complementary techniques (linear/spline regressions, a multivariate analogue method, artificial neural networks and recursive gap filling) was used to reconstruct missing meteorological data. The complete surface energy budget was then obtained for two dominant land cover types, fallow bush and millet, by applying the meteorological forcing data set to a finely field-calibrated land surface model. Uncertainty in reconstructed data was expressed by means of a stochastic ensemble of plausible historical time series. Climatological statistics were computed at sub-daily to decadal timescales and compared with local, regional and global data sets such as CRU and ERA-Interim. The reconstructed precipitation statistics, ˜1°C increase in mean annual temperature from 1950 to 2009, and mean diurnal and annual cycles for all variables were in good agreement with previous studies. The new data set, denoted NAD (Niamey Airport-derived set) and publicly available, can be used

  3. Investigating the Relationship between the Inter-Annual Variability of Satellite-Derived Vegetation Phenology and a Proxy of Biomass Production in the Sahel

    Directory of Open Access Journals (Sweden)

    Michele Meroni

    2014-06-01

    Full Text Available In the Sahel region, moderate to coarse spatial resolution remote sensing time series are used in early warning monitoring systems with the aim of detecting unfavorable crop and pasture conditions and informing stakeholders about impending food security risks. Despite growing evidence that vegetation productivity is directly related to phenology, most approaches to estimate such risks do not explicitly take into account the actual timing of vegetation growth and development. The date of the start of the season (SOS or of the peak canopy density can be assessed by remote sensing techniques in a timely manner during the growing season. However, there is limited knowledge about the relationship between vegetation biomass production and these variables at the regional scale. This study describes the first attempt to increase our understanding of such a relationship through the analysis of phenological variables retrieved from SPOT-VEGETATION time series of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR. Two key phenological variables (growing season length (GSL; timing of SOS and the maximum value of FAPAR attained during the growing season (Peak are analyzed as potentially related to a proxy of biomass production (CFAPAR, the cumulative value of FAPAR during the growing season. GSL, SOS and Peak all show different spatial patterns of correlation with CFAPAR. In particular, GSL shows a high and positive correlation with CFAPAR over the whole Sahel (mean r = 0.78. The negative correlation between delays in SOS and CFAPAR is stronger (mean r = −0.71 in the southern agricultural band of the Sahel, while the positive correlation between Peak FAPAR and CFAPAR is higher in the northern and more arid grassland region (mean r = 0.75. The consistency of the results and the actual link between remote sensing-derived phenological parameters and biomass production were evaluated using field measurements of aboveground herbaceous biomass

  4. Sahel Medical Journal: Submissions

    African Journals Online (AJOL)

    338-41, N ENGL J Med 1991; 324:24-8. Journal title should conform to the abbreviations used in Index Medicus. Please avoid dots or comas after these abbreviations. Examples of references are given below. For Journal Articles: Osuntokun B O ...

  5. Sequía, inmigración y políticas locales: el Sahel en la encrucijada del desarrollo

    Directory of Open Access Journals (Sweden)

    Sara Nso

    2008-10-01

    Full Text Available Este artículo trata de delimitar los principales factores socio-económicos y políticos que ponen en relación desertificación y flujos migratorios internacionales, en el área Sahel. A través del estudio -no exhaustivo para todos los países de la muestra, por ausencia de datos disponibles- de dichas realidades en Burkina Faso, Gambia, Guinea-Bissau, Guinea, Malí, Mauritania, Níger y Senegal, el análisis del elemento local será privilegiado, sin despreciar por ello el valor de las dinámicas regionales. Desde una perspectiva "transnacionalista", se aportarán así las claves para la comprensión global de la problemática saheliana, con el objetivo de sacar a esta región de la encrucijada del subdesarrollo.

  6. Modelling spatial and temporal dynamics of gross primary production in the Sahel from earth-observation-based photosynthetic capacity and quantum efficiency

    DEFF Research Database (Denmark)

    Tagesson, Håkan Torbern; Ardoe, Jonas; Cappelaere, Bernard

    2017-01-01

    . MOD17A2H GPP (collection 6) drastically underestimated GPP, most likely because maximum light use efficiency is set too low for semi-arid ecosystems in the MODIS algorithm. Intra-annual dynamics in Fopt were closely related to SIWSI being sensitive to equivalent water thickness, whereas α was closely......: (1) to evaluate the MOD17A2H GPP (collection 6) product against GPP based on eddy covariance (EC) for six sites across the Sahel; (2) to characterize relationships between spatial and temporal variability in EC-based photosynthetic capacity (Fopt) and quantum efficiency (α) and vegetation indices...... related to RDVI being affected by chlorophyll abundance. Spatial and inter-annual dynamics in Fopt and α were closely coupled to NDVI and RDVI, respectively. Modelled GPP based on Fopt and α upscaled using EO-based indices reproduced in situ GPP well for all except a cropped site that was strongly...

  7. Increasing the Effectiveness of the “Great Green Wall” as an Adaptation to the Effects of Climate Change and Desertification in the Sahel

    Directory of Open Access Journals (Sweden)

    David O'Connor

    2014-10-01

    Full Text Available The Great Green Wall (GGW has been advocated as a means of reducing desertification in the Sahel through the planting of a broad continuous band of trees from Senegal to Djibouti. Initially proposed in the 1980s, the plan has received renewed impetus in light of the potential of climate change to accelerate desertification, although the implementation has been lacking in all but two of 11 countries in the region. In this paper, we argue that the GGW needs modifying if it is to be effective, obtain the support of local communities and leverage international support. Specifically, we propose a shift from planting trees in the GGW to utilizing shrubs (e.g., Leptospermum scoparium, Boscia senegalensis, Grewia flava, Euclea undulata or Diospyros lycioides, which would have multiple benefits, including having a faster growth rate and proving the basis for silvo-pastoral livelihoods based on bee-keeping and honey production.

  8. Linking the sub-Saharan and West Eurasian gene pools: maternal and paternal heritage of the Tuareg nomads from the African Sahel.

    Science.gov (United States)

    Pereira, Luísa; Cerný, Viktor; Cerezo, María; Silva, Nuno M; Hájek, Martin; Vasíková, Alzbeta; Kujanová, Martina; Brdicka, Radim; Salas, Antonio

    2010-08-01

    The Tuareg presently live in the Sahara and the Sahel. Their ancestors are commonly believed to be the Garamantes of the Libyan Fezzan, ever since it was suggested by authors of antiquity. Biological evidence, based on classical genetic markers, however, indicates kinship with the Beja of Eastern Sudan. Our study of mitochondrial DNA (mtDNA) sequences and Y chromosome SNPs of three different southern Tuareg groups from Mali, Burkina Faso and the Republic of Niger reveals a West Eurasian-North African composition of their gene pool. The data show that certain genetic lineages could not have been introduced into this population earlier than approximately 9000 years ago whereas local expansions establish a minimal date at around 3000 years ago. Some of the mtDNA haplogroups observed in the Tuareg population were involved in the post-Last Glacial Maximum human expansion from Iberian refugia towards both Europe and North Africa. Interestingly, no Near Eastern mtDNA lineages connected with the Neolithic expansion have been observed in our population sample. On the other hand, the Y chromosome SNPs data show that the paternal lineages can very probably be traced to the Near Eastern Neolithic demic expansion towards North Africa, a period that is otherwise concordant with the above-mentioned mtDNA expansion. The time frame for the migration of the Tuareg towards the African Sahel belt overlaps that of early Holocene climatic changes across the Sahara (from the optimal greening approximately 10 000 YBP to the extant aridity beginning at approximately 6000 YBP) and the migrations of other African nomadic peoples in the area.

  9. Sahara and Sahel vulnerability to climate changes, lessons from the past - Focus on the Ounianga lake region (NE Chad)

    Science.gov (United States)

    Grenier, Christophe; Zheng, Weipeng; Lezine, Anne-Marie; Braconnot, Pascale; Krinner, Gerhard; Harel, Marie-Alice; Anglade, Juliette; Paillou, Philippe

    2010-05-01

    Reconstructions from sedimentary records and climate modelling results show an overall drying in the African Sahara and Sahel during the Holocene. Was this change abrupt or gradual, and amplified or not through vegetation change and feedbacks to the atmosphere is still the subject of debate. For instance, while [deMenocal et al. 2000] show from oceanic sediments off the Mauritanian coast, that the end of the African Humid Period (AHP), recorded 5500 years ago, was abrupt. [Kroepelin et al., 2008] studied recently sediments from lake Yoa (Ounianga region, NE Chad) and derived a gradual climate change. The present paper focusses on the Ounianga lake region (NE Chad) where the Kropelin et al. study was carried on. We investigate hydrological reconstructions based on climate scenarios and modelling of water dynamics of the catchment area of the lakes. Under modern conditions, Ounianga lakes are maintained in a hyper arid environment due to groundwater inputs from the Nubian Sandstone Aquifer System (NSAS), a very large aquifer covering parts of Chad, Libya, Egypt and Sudan. Moreover, these lakes are situated within 200 km of the Tibesti Mountains ranging over 3000 meters where rainfall is larger than in the plains. So the issue arises as to what extent distant water inputs from the Tibesti and local groundwater recharge could have maintained high lake levels during the climatic transition phase and/or could explain some features analysed from the sediments regarding the abruptness of the salinisation of lake Yoa roughly by 3900 BP. The topography of the region is analyzed from SRTM data to obtain paleo river networks and compared with satellite radar pictures (PALSAR) to identify key features in the Yoa catchement area [refer to Grenier et al. 2009]. A hydrological model is constructed including the river network and depressions interpreted as lakes and modeled dynamically as reservoirs. The groundwater input from the aquifer is modeled within the Cast3m finite element

  10. Mali and Nigeria Should be Established as Key Regional Partners of the United States to Further Mutual Interests for Ensuring Long-Term Security and Stability in the Sahel Region

    Science.gov (United States)

    2016-06-10

    who was paid 200 kg of gold by King Musa Keita the First according to Ibn Khaldun, one of the best known sources for 14th century Mali. 4 oldest...gradually regained some attentions as the ripples effects of the Sahel issues impacted Western societies . Thus, several Western countries, particularly...where Russia was intruding) or the Levant (where ISIS had just reduced 10 years of enduring efforts in Iraq into nil). Today, in of view of the

  11. The paradoxical evolution of runoff in the pastoral Sahel: analysis of the hydrological changes over the Agoufou watershed (Mali) using the KINEROS-2 model

    Science.gov (United States)

    Gal, Laetitia; Grippa, Manuela; Hiernaux, Pierre; Pons, Léa; Kergoat, Laurent

    2017-09-01

    In recent decades, the Sahel has witnessed a paradoxical increase in surface water despite a general precipitation decline. This phenomenon, commonly referred to as the Sahelian paradox, is not completely understood yet. The role of cropland expansion due to the increasing food demand by a growing population has been often put forward to explain this situation for the cultivated Sahel. However, this hypothesis does not hold in pastoral areas where the same phenomenon is observed. Several other processes, such as the degradation of natural vegetation following the major droughts of the 1970s and the 1980s, the development of crusted topsoils, the intensification of the rainfall regime and the development of the drainage network, have been suggested to account for this situation. In this paper, a modeling approach is proposed to explore, quantify and rank different processes that could be at play in pastoral Sahel. The kinematic runoff and erosion model (KINEROS-2) is applied to the Agoufou watershed (245 km2), in the Gourma region in Mali, which underwent a significant increase of surface runoff during the last 60 years. Two periods are simulated, the past case (1960-1975) preceding the Sahelian drought and the present case (2000-2015). Surface hydrology and land cover characteristics for these two periods are derived by the analysis of aerial photographs, available in 1956, and high-resolution remote sensing images in 2011. The major changes identified are (1) a partial crusting of isolated dunes, (2) an increase of drainage network density, (3) a marked decrease in vegetation with the nonrecovery of tiger bush and vegetation growing on shallow sandy soils, and (4) important changes in soil properties with the apparition of impervious soils instead of shallow sandy soil. The KINEROS-2 model was parameterized to simulate these changes in combination or independently. The results obtained by this model display a significant increase in annual discharge between the

  12. The paradoxical evolution of runoff in the pastoral Sahel: analysis of the hydrological changes over the Agoufou watershed (Mali using the KINEROS-2 model

    Directory of Open Access Journals (Sweden)

    L. Gal

    2017-09-01

    Full Text Available In recent decades, the Sahel has witnessed a paradoxical increase in surface water despite a general precipitation decline. This phenomenon, commonly referred to as the Sahelian paradox, is not completely understood yet. The role of cropland expansion due to the increasing food demand by a growing population has been often put forward to explain this situation for the cultivated Sahel. However, this hypothesis does not hold in pastoral areas where the same phenomenon is observed. Several other processes, such as the degradation of natural vegetation following the major droughts of the 1970s and the 1980s, the development of crusted topsoils, the intensification of the rainfall regime and the development of the drainage network, have been suggested to account for this situation. In this paper, a modeling approach is proposed to explore, quantify and rank different processes that could be at play in pastoral Sahel. The kinematic runoff and erosion model (KINEROS-2 is applied to the Agoufou watershed (245 km2, in the Gourma region in Mali, which underwent a significant increase of surface runoff during the last 60 years. Two periods are simulated, the past case (1960–1975 preceding the Sahelian drought and the present case (2000–2015. Surface hydrology and land cover characteristics for these two periods are derived by the analysis of aerial photographs, available in 1956, and high-resolution remote sensing images in 2011. The major changes identified are (1 a partial crusting of isolated dunes, (2 an increase of drainage network density, (3 a marked decrease in vegetation with the nonrecovery of tiger bush and vegetation growing on shallow sandy soils, and (4 important changes in soil properties with the apparition of impervious soils instead of shallow sandy soil. The KINEROS-2 model was parameterized to simulate these changes in combination or independently. The results obtained by this model display a significant increase in annual

  13. Process-based modeling of coupled energy and water cycle under dry tropical conditions: an experiment at local scale in the cultivated Sahel (South-West Niger)

    Science.gov (United States)

    Velluet, C.; Demarty, J.; Cappelaere, B.; Braud, I.; Boulain, N.; Charvet, G.; Chazarin, J.-P.; Mainassara, I.; Boucher, M.; Issoufou, H. B.-A.; Ibrahim, M.; Oi, M.; Ramier, D.; Benarrosh, N.; Yahou, H.

    2012-04-01

    In the dry tropics in general and, particularly in the African Sahel, agro-ecosystems and hydrosystems are very sensitive to climate variability and land management. In turn, it has been shown that soil moisture, vegetation and surface fluxes produce substantial feedback effects on rainfall-producing atmospheric convection. Therefore, it is of prime importance to understand and to model the dynamics of the soil-plant-atmosphere continuum in response to contrasted meteorological and terrestrial conditions for this area. The objective of this study is to produce a process-based model of water and energy transfers in the soil and land-atmosphere interface over an entire 5-year period, at local scale, for the two main land cover types of South-West Niger: millet-crop and fallow savannah. A comprehensive dataset is available over that whole period in two such fields of the Wankama catchment, making it a rather unique asset for West Africa. This area is typical of the central Sahel conditions, with ~400-600 mm annual rainfall concentrated in the 4-5 months wet season, followed by the 7-8 months dry season. Soils are essentially sandy and prone to surface crusting, which induces a strong vertical contrast in hydrodynamic properties. The dataset used here includes 5 years of atmospheric forcing (rainfall, wind speed, sun and atmosphere radiation, air temperature and moisture) and validation variables (net radiation, turbulent fluxes and soil temperature and moisture profiles), recorded every 30 min. The seasonal course of vegetation phenology (LAI, height, biomass) and soil characteristics (particle size and density profiles) are also available. The SiSPAT (Simple Soil-Plant-Atmosphere Transfer, Braud et al., 1995) physically-based model is used for this study. It solves the mass and heat transfer system of equations in the soil, with vapour phase, coupled with a two-component (bare soil and one vegetation layer) water and energy budget at the surface-atmosphere interface

  14. More Yield with Less Water: Increasing Water Use Efficiency by Capitalizing on the Adaptation of Native Shrubs in the Sudano-Sahel

    Science.gov (United States)

    Bogie, Nathaniel; Bayala, Roger; Diedhiou, Ibrahima; Dick, Richard; Ghezzehei, Teamrat

    2016-04-01

    A changing climate along with human and animal population pressure can have a devastating effect on crop yields and food security in the Sudano-Sahel. Agricultural solutions to address soil degradation and crop water stress are needed to combat this increasingly difficult situation. Significant differences in crop success have been observed in peanut and millet grown in association with two native evergreen shrubs Piliostigma reticulatum, and Guiera senegalensis at the sites of Nioro du Rip and Keur Matar, respectively. We investigate how farmers can increase crop productivity by capitalizing on the evolutionary adaptation of native shrubs to the harsh Sudano-Sahelian environment as well as the physical mechanisms at work in the system that can lead to more robust yields. Research plots at Keur Matar Arame with no fertilizer added were monitored in 2013 using two soil moisture sensor networks at depths of 10, 20, 40, 60, 100, 200, and 300cm. Cropping season water use total calculated based on beginning and end of season soil moisture and seasonal precipitation data revealed that crop-only plot used 411±32 mm of water, and the crop and shrub plot used 439±42 mm of water. Taking into account the quantity of crop biomass produced and neglecting the shrub biomass produced, the crop and shrub plot had a water use efficiency of 1.60 kg ha-1 mm-1 and the crop only plot had 0.269 kg ha-1 mm-1. Water status was measured three times throughout the season on millet leaves and revealed no significant trends. Handheld NDVI readings revealed significantly higher NDVI values in crop and shrub plots at all measurement dates. These findings build on work that was completed in 2004 at the site, but further increases in crop yields have been shown. Increasing water use efficiency by over 500% can be a great advantage in years of limited water availability such as 2013. Using even the limited resources that farmers possess, this agroforestry technique can be expanded over wide

  15. A comparison of the physical properties of desert dust retrieved from the sunphotometer observation of major events in the Sahara, Sahel, and Arabian Peninsula

    KAUST Repository

    Masmoudi, Mohamed

    2015-05-01

    © 2015 Elsevier B.V. The objective of this work is to assess the variability of the size-distribution, real (n) and imaginary (k) parts of the refractive index, asymmetry parameter (g), and single scattering albedo (SSA) of desert dust events observed in the Sahara, Sahel, and Arabian Peninsula areas. For this we use the level-2 inversions of 14 AERONET sunphotometers representative of the area of study. In the dataset, the dust-dominated events are discriminated on the basis of their large optical depth and low (<. 0.3) Ångström exponent (α) calculated between 440. nm and 870. nm. In all the volume size-distributions a coarse mode (CM) of particles is observed but a fine mode (FM) of particles with radii. <. 0.2. μm is also present. The volume fraction represented by the FM is lower (3%) during the most intense dust storms than during moderate ones (12%). The inter-site variability of the characteristics of the CM-dominated situations is found to be non-significant and at 440, 675, 870, and 1020. nm a common set of values can be adopted for n (1.54 ± 0.03, 1.53 ± 0.02, 1.50 ± 0.02, 1.48 ± 0.02), k (0.0037 ± 0.0007, 0.0012 ± 0.0002, 0.0011 ± 0.0002, 0.0012 ± 0.0002), g (0.77 ± 0.01, 0.74 ± 0.01, 0.73 ± 0.01, 0.74 ± 0.01), and the SSA (0.90 ± 0.02, 0.97 ± 0.01, 0.98 ± 0.01, 0.98 ± 0.01). However; during the less intense dust-events the growing influence of the FM leads to regional differentiation of the dust properties and 2 main areas can be distinguished: 1) the relatively clean central Sahara/Sahel, and 2) the more polluted continuum constituted by the Mediterranean coast and the Arabian Peninsula.

  16. Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali

    Directory of Open Access Journals (Sweden)

    J. Gardelle

    2010-02-01

    Full Text Available Changes in the flooded area of ponds in the Gourma region from 1950 to present are studied by remote sensing, in the general context of the current multi-decennial Sahel drought. The seasonal and interannual variations of the areas covered by surface water are assessed using multi-date and multi-sensor satellite images (SPOT, FORMOSAT, LANDSAT-MSS, –TM, and -ETM, CORONA, and MODIS and aerial photographs (IGN. Water body classification is adapted to each type of spectral resolution, with or without a middle-infrared band, and each spatial resolution, using linear unmixing for mixed pixels of MODIS data. The high-frequency MODIS data document the seasonal cycle of flooded areas, with an abrupt rise early in wet season and a progressive decrease in the dry season. They also provide a base to study the inter-annual variability of the flooded areas, with sharp contrasts between dry years such as 2004 (low and early maximal area and wetter years such as 2001 and 2002 (respectively high and late maximal area.The highest flooded area reached annually greatly depends on the volume, intensity and timing of rain events. However, the overall reduction by 20% of annual rains during the last 40 years is concomitant with an apparently paradoxical large increase in the area of surface water, starting from the 1970's and accelerating in the mid 1980's. Spectacular for the two study cases of Agoufou and Ebang Mallam, for which time series covering the 1954 to present period exist, this increase is also diagnosed at the regional scale from LANDSAT data spanning 1972–2007. It reaches 108% between September 1975 and 2002 for 91 ponds identified in central Gourma. Ponds with turbid waters and no aquatic vegetation are mostly responsible for this increase, more pronounced in the centre and north of the study zone. Possible causes of the differential changes in flooded areas are discussed in relation with the specifics in topography, soil texture and vegetation

  17. Accelerating improvements in nutritional and health status of young children in the Sahel region of Sub-Saharan Africa: review of international guidelines on infant and young child feeding and nutrition.

    Science.gov (United States)

    Wuehler, Sara E; Hess, Sonja Y; Brown, Kenneth H

    2011-04-01

    The United Nations Convention on the Rights of the Child holds governments responsible to ensure children's right to the highest attainable standard of health by providing breastfeeding support, and access to nutritious foods, appropriate health care, and clean drinking water. International experts have identified key child care practices and programmatic activities that are proven to be effective at reducing infant and young child undernutrition, morbidity, and mortality. Nevertheless, progress towards reducing the prevalence of undernutrition has been sporadic across countries of the Sahel sub-region of Sub-Saharan Africa. In view of this uneven progress, a working group of international agencies was convened to 'Reposition children's right to adequate nutrition in the Sahel.' The first step towards this goal was to organize a situational analysis of the legislative, research, and programmatic activities related to infant and young child nutrition (IYCN) in six countries of the sub-region: Burkina Faso, Chad, Mali, Mauritania, Niger, and Senegal. The purposes of this introductory paper are to review current information concerning the nutritional and health status of infants and young children in the Sahel and to summarize international guidelines on optimal IYCN practices. These guidelines were used in completing the above-mentioned situational analyses and encompass specific recommendations on: (i) breastfeeding (introduction within the first hour after birth, exclusivity to 6 months, continuation to at least 24 months); (ii) complementary feeding (introduction at 6 months, use of nutrient dense foods, adequate frequency and consistency, and responsive feeding); (iii) prevention and/or treatment of micronutrient deficiencies (vitamin A, zinc, iron and anaemia, and iodine); (iv) prevention and/or treatment of acute malnutrition; (v) feeding practices adapted to the maternal situation to reduce mother-to-child transmission of HIV; (vi) activities to ensure food

  18. People and pixels in the Sahel: a study linking coarse-resolution remote sensing observations to land users' perceptions of their changing environment in Senegal

    Directory of Open Access Journals (Sweden)

    Stefanie M. Herrmann

    2014-09-01

    Full Text Available Mounting evidence from satellite observations of a re-greening across much of the Sahel and Sudan zones over the past three decades has raised questions about the extent and reversibility of desertification. Historical ground data that could help in interpreting the re-greening are scarce. To fill that void, we tapped into the collective memories of local land users from central and western Senegal in 39 focus groups and assessed the spatial association between their perceptions of vegetation changes over time and remote sensing-derived trends. To provide context to the vegetation changes, we also explored the land users' perspective on the evolution of other environmental and human variables that are potentially related to the greening, using participatory research methods. While increases in vegetation were confirmed by the study participants for certain areas, which spatially corresponded to satellite-observed re-greening, vegetation degradation dominated their perceptions of change. This degradation, although spatially extensive according to land users, flies under the radar of coarse-resolution remote sensing data because it is not necessarily associated with a decrease in biomass but rather with undesired changes in species composition. Few significant differences were found in the perceived trends of population pressure, environmental, and livelihood variables between communities that have greened up according to satellite data and those that have not. Our findings challenge the prevailing chain of assumptions of the satellite-observed greening trend indicating an improvement of environmental conditions in the sense of a rehabilitation of the vegetation cover after the great droughts of the 1970s and 1980s, and the improvement of environmental conditions possibly translating into more stable livelihoods and greater well-being of the populations. For monitoring desertification and rehabilitation, there is a need to develop remote sensing

  19. Calorific value of Prosopis africana and Balanites aegyptiaca wood: Relationships with tree growth, wood density and rainfall gradients in the West African Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Carmen Sotelo; Weber, John C. [World Agroforestry Centre (ICRAF), Sahel Office, B.P. E 5118 Bamako (Mali); Silva, Dimas Agostinho da; Bolzon de Muniz, Graciela Ines [Universidade Federal do Parana (UFPR), Av. Lothario Meissner, 900, CEP.: 80270-170-Curitiba (Brazil); Garcia, Rosilei A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Instituto de Florestas, Departamento de Produtos Florestais, BR 465, km 07, 23890-000, Seropedica, Rio de Janeiro (Brazil)

    2011-01-15

    Prosopis africana and Balanites aegyptiaca are native tree species in the West African Sahel and provide wood for fuel, construction and other essential products. A provenance/progeny test of each species was established at one relatively dry site in Niger, and evaluated at 13 years. Gross calorific value of the wood was determined for a random sample of trees in each test: gross CV and CVm{sup 3} = gross calorific value in MJ kg{sup -1} and MJ m{sup -3}, respectively. The major objectives were to determine if gross CV was positively correlated with wood density and tree growth, and if gross CV and/or CVm{sup 3} varied with rainfall gradients in the sample region. Provenances were grouped into a drier and more humid zone, and correlations were computed among all trees and separately in each zone. Results indicated that gross CV was not significantly correlated with density in either species. Gross CV was positively correlated with growth of P. africana (but not B. aegyptiaca) only in the drier zone. Gross CVm{sup 3} was positively correlated with growth of both species, and the correlations were stronger in the drier zone. Multiple regressions with provenance latitude, longitude and elevation indicated that provenance means for gross CV increased, in general, from the drier to the more humid zones. Regressions with gross CVm{sup 3} were not significant. Results are compared with earlier research reports from the provenance/progeny tests and with other tropical hardwood species; and practical implications are presented for tree improvement and conservation programs in the region. (author)

  20. Phenotypic homogeneity with minor deviance in osmotic fragility of Sahel goat erythrocytes in non-ionic sucrose media during various physiologic states.

    Science.gov (United States)

    Igbokwe, Nanacha Afifi; Igbokwe, Ikechukwu Onyebuchi

    2016-11-01

    Erythrocyte swelling in non-ionic sucrose media and the subsequent osmotic lysis are influenced by mechanisms of regulatory volume adjustment and osmotic water permeability. Kinetics of transmembrane water and ion fluxes in varied physiologic states may determine the phenotype of erythrocyte osmotic fragility (EOF) and affect estimates of EOF. Effects of sex, age, late pregnancy (third trimester) and lactation on the haemolysis of Sahel goat erythrocytes incubated in a series of hyposmotic non-ionic sucrose media were investigated. The fragiligram was sigmoidal in 72 (97%) out of 74 goats. Two male (3%) goats with low and high extreme median erythrocyte fragilities (MEF), had non-sigmoidal curves. The mean fragilities at osmolarities of 30-300 mosmol/L of sucrose and the mean osmolarities responsible for 10%-90% haemolysis (CH10-CH90) were not significantly different between males and non-pregnant dry (NPD) females, amongst the age groups and between pregnant or lactating and NPD female goats. The MEF (CH50) of the goats were at osmolarities of 126-252 mosmol/L (median of data: 171 mosmol/L) with a mean of 175.24±16.20 mosmol/L. Therefore, phenotypic homogeneity of EOF occurred with minor deviance, since EOF variables were not differentiated by sex, age, late pregnancy or lactation. Physiologic states of the goat did not affect EOF phenotype in non-ionic sucrose media. Sigmoidal fragility phenotype seemed to be homogeneously conserved by osmoregulatory mechanisms not partitioned by sex, age, late pregnancy or lactation, but a minor non-sigmoidal curve might have occurred due to altered erythrocyte osmotic behaviour that would require further investigation.

  1. Klimatické změny a výzvy rozvojových zemí s cílem směřujícím na Sahel

    OpenAIRE

    Nohelová, Kateřina

    2014-01-01

    The aim of the thesis is to analyze the development of climate change in the Sahel belt of Sub-Saharan Africa. The thesis is focused on West Africa including Mali, Niger, Mauritania, Senegal and Chad. The challenge is to use two composite indicators, which will then be evaluated in table and graphical form in the five-year period that also typify the economic and environmental situation in the region. It will also study the effect of climate change on agricultural land, its transformation and...

  2. “El florecimiento del terrorismo islámico en el Sahel, un reto para la seguridad de Europa Occidental. Estudio de caso: Malí y España (2011- 2013)”

    OpenAIRE

    Rodríguez Uribe, Mónica Alejandra

    2015-01-01

    El objetivo central de este Estudio de Caso, consiste en investigar en qué sentido la proximidad geográfica y el hecho de que la región del Sahel constituya una zona de tránsito, influyen a que el crecimiento del terrorismo islámico en Malí comprenda una amenaza tanto para la seguridad nacional, como para la estabilidad de España. Se avanzará posteriormente con la descripción de herramientas específicas, tanto judiciales como de cooperación que el gobierno español ha buscado apoyar a nivel ...

  3. Sahel Medical Journal: Editorial Policies

    African Journals Online (AJOL)

    ... social scientists engaged in health care delivery and ensures the highest ethical and scientific standards in all articles and materials it accepts to publish. The SMJ shall seek to actively remedy the falling standards of ethics among practitioners and students of medicine alike, through publication of articles in medical ethics ...

  4. Sahel Medical Journal: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  5. Sahel, North-West Nigeria

    African Journals Online (AJOL)

    Nneka Umera-Okeke

    Table 1: Result of correlation of Rainfall data from CRU data set with measured data from NIMET (Yelwa Station). Data Point. Multiple R. R Square Adjusted R ... regression on x. In Augi town, lowest rainfall was recorded in 1982 with annual rainfall of 379.3mm. Other years of significantly low rains are 1973 (379.7mm), 1987 ...

  6. Joël Vernet (Ed.), Pays du Sahel. Du Tchad au Sénégal, du Mali au Niger, Paris, Autrement, Série Monde H.S. N° 72, Janvier 1994.

    OpenAIRE

    Salzbrunn, Monika

    2007-01-01

    Quel est le relief de ce paysage nommé Sahel, se dressant de la côte atlantique jusqu'au Tchad ? Joël Vernet invite le lecteur à suivre les traces de différentes civilisations du "rivage" en proposant 22 approches variées. Parmi les auteurs : Catherine Belvaude, André Bourgeot, Hélène Claudot‑Haward, Mamadou Diouf, René Dumont, Jean Gallais, M. Mbaye Gueye, Théodore Monod, Jean Suret‑Canale, Charles Toupet. Le trajet commence par une revue de la "découverte" de l'Afrique par des voyageurs eur...

  7. Petite motorisation et exploitations maraîchères de taille limitée du Sahel tunisien Partie 2: Evaluation sur le terrain des performances et des coûts de préparation du sol

    Directory of Open Access Journals (Sweden)

    Chehaibi, S.

    2003-01-01

    Full Text Available Low Power Mechanisation and Small-scale Vegetable Production in the Tunisian Sahel Region. Part 2: On the Field Evaluation of Performances and of Soil Preparation Costs. In this study, it was investigated to what extent low power mechanisation could be introduced in vegetable production in the Tunisian Sahel region by evaluating its performance (labour input and field efficiency by means of field experiments in which different traction equipment was used for carrying out several cultivation operations. Furthermore, costs per unit area for soil preparation in both sandy clay and clayish sand were calculated for four different power classes and for small fields. The results showed that two wheel tractors had a real labour input for scuffling between plant rows ranging from 11.3 h/ha to 18.7 h/ha. These inputs ranged from 5.5 h/ha to 6.7 h/ha for tied crops. For mowing, the two wheel tractor had labour inputs of 17.3 and 14.2 h/ha for the first and the second cut, respectively, while for potato digging, the first and the second passage of secondary tillage these values were 11.5, 14.3 and 10.4 h/ha, respectively. Superficial soil preparation by means of a four wheel tractor gave rise to values between 2.7 and 3.5 h/ha. With respect to the cost estimation for soil preparation, the lowest costs were obtained by means of the low power mechanisation. Similar conclusions were drawn for the field efficiencies for the operations investigated. In general, these efficiencies were above 70%.

  8. Les unités pastorales du Sahel sénégalais, outils de gestion de l’elevage et des espaces pastoraux. projet durable ou projet de développement durable ?

    Directory of Open Access Journals (Sweden)

    Abdrahmane Wane

    2006-12-01

    Full Text Available Au Ferlo (Sahel sénégalais, la durabilité de l’élevage pastoral repose sur la diversité et la flexibilité des régimes de mobilité. Depuis les années 90, le Projet d’Appui à l’Elevage (PAPEL intervient dans la zone pour organiser la gestion des ressources naturelles à l’échelle des unités pastorales (UP, avec l’objectif affiché d’assurer le contrôle et la durabilité de cette activité. Nous avons tenté d’évaluer la pertinence de la généralisation de ce projet d’envergure à l’aune des caractéristiques propres au pastoralisme, dorénavant reconnu comme la meilleure forme de mise en valeur dans l’environnement incertain du Ferlo. Même si les unités pastorales de gestion des ressources ont prouvé leur intérêt dans plusieurs cas de la première phase du projet en zone pastorale, il semble que dans le contexte sénégalais actuel de politique sectorielle agricole, et d’accaparement privé des ressources foncières, la généralisation systématique du schéma des UP sur tout le territoire risquerait plutôt de menacer la durabilité de la mobilité pastorale.In Ferlo (Senegalese Sahel, the sustainability of the livestock farming depends on the diversity and the flexibility of the regulations of mobility. Since the 90s, the PAPEL (Senegalese Support Project for Livestock has intervened in the area in order to manage the natural resources on the scale of the pastoral units (UP with the declared objective to ensure the control and the sustainability of this activity.  We tried to estimate the relevance of the general implementation of this large-scale project by the yardstick of the characteristics peculiar to Pastoralism, henceforth known as the best valorisation form in the uncertain environment of Ferlo. Even if the pastoral units as tools of the natural resource management have demonstrated their interest in many cases of the first stage of the project in the pastoral area, it seems that, in the

  9. Better fertilizer use in the Sahel

    International Development Research Centre (IDRC) Digital Library (Canada)

    the availability of soil nutrients and moisture for crops in the four countries involved. As cowpea is traditionally grown by women, expanding its production will enhance household income while promoting gender equity. In the process, researchers will also examine the long-term effects of fertilizer micro-dosing on potential.

  10. Exploring land use change in the Sahel

    DEFF Research Database (Denmark)

    Rasmussen, Laura Vang

    perceptions of land use changes became apparent, however, already in the beginning of 2000, when researchers within the Land Change Science community raised their concerns about general narratives of field expansions that were assumed to progress linearly and be solely driven by population growth. Calls...... food production as the primary outcome as crop residues used for fodder have become the major focus. The thesis thereby demonstrates the need to re-examine the evidence on which stories of field expansion are based and questions the way in which Sahelian land use changes are conceptualized...... for more research on Sahelian land use changes have thus multiplied as the complexity and sometimes intricate processes of land change became apparent, and especially, the need for novel approaches that combine different perspectives has continuously been highlighted. As part of the interdisciplinary...

  11. Antiphospholipids antibodies and migraine | Nyandaiti | Sahel ...

    African Journals Online (AJOL)

    Similarly, antiphospholipid antibodies was significantly elevated in migraine patients with aura compared to those without aura, ( 2=0.037; p<0.05). The frequency of migraine attacks correlated positively with the concentration of lgG anti β2GP1; ( p<0.05). Conclusion: We demonstrated increased serum level of lgG anti ...

  12. Visual impairment among commercial motorcyclists | Edema | Sahel ...

    African Journals Online (AJOL)

    One point four percent (1.4%) had subnormal visual acuity, while 5.3% had refractive errors. Ocular pathologies were found in 11.5% of the eyes examined. Conclusion: Most commercial motorcyclists may pass the Federal Road Safety Corps. However Colour vision and visual field testing may give a more reliable result.

  13. Gumbel Weibull distribution function for Sahel precipitation ...

    African Journals Online (AJOL)

    We computed the parameters using four computations methods such as: method of moments (MOM), maximum likelihood method (MLM), method of least squares (MLS) and probability weighted moments (PWM). To estimate the best method, firstly we used several good fit tests like: Kolmogorov-Smirnov (Ks), Chi-square, ...

  14. Analyzing Sanctuary Management in the Sahel

    Science.gov (United States)

    2015-06-12

    pandemics such as HIV / AIDS and Ebola originating in Africa . Currently, the U.S. has forces deployed to Liberia to contain the Ebola outbreak. U.S... HIV / AIDS epidemics. This is a recent development. Formerly, U.S. policymakers did not recognize African issues as strategic priorities, and American...of the Maghreb (AQIM) and other extremist organizations are using wide and multiple areas of Africa , particularly from northern Mali to southern Libya

  15. Sahel Journal of Veterinary Sciences: Submissions

    African Journals Online (AJOL)

    Hafez, E. S. E., ed.), Lea and Febiger, Philadelphia, PA., USA. pp. 247-283. Page Charges The author will be required to pay a handling charge of N=1000.00 (US $10.00) and a page charge of N=300.00 (US $5.00) per typed (A4) page of the ...

  16. Mise en évidence en subsurface d'événements compressifs Éocène moyen supérieur en Tunisie orientale (Sahel) : généralité de la phase atlasique en Afrique du Nord

    Science.gov (United States)

    Khomsi, Sami; Bédir, Mourad; Soussi, Mohamed; Ben Jemia, Mohamed Ghazi; Ben Ismail-Lattrache, Kmar

    2006-01-01

    Compressional events are well recognized, in the subsurface of the Sahel foreland basin in eastern Tunisia, evolving toward the Palaeogene sedimentary cover. These events are expressed by folds, inversional structures and a set of angular unconformities. The compressional events that started in the Campanian-Maastrichtian continued through the Palaeocene and attempted their paroxysm in the Lutetian-Priabonian prior to the angular toplap unconformity of the Oligocene series. On the other hand, the Oligo-Miocene series recorded tectonic quiescence events expressed by extensional tectonics. The tectonic events recorded by the Palaeogene series are well correlated to the major events recognized in eastern Algeria, especially the Atlasic event (Lutetian-Priabonian), which must be considered as a major tectonic event largely expressed in the whole Atlasic domain of North Africa. To cite this article: S. Khomsi et al., C. R. Geoscience 338 (2006).

  17. Prolonged hospital stay in measles patients | Ashir | Sahel Medical ...

    African Journals Online (AJOL)

    Background: Measles is still a major cause of childhood morbidity and mortality in Nigeria despite the availability of safe and effective vaccines. The burden of measles using length of hospital stay as a result of complications in hospitalised children with measles is reported. Methods: We carried out a two year retrospective ...

  18. Les femmes du Sahel obtiennent de meilleurs rendements de leurs ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    7 juin 2016 ... Elle sert de garantie pour l'obtention de crédit auprès des institutions de microfinance. Là où le projet est exécuté, une vingtaine d'institutions de microfinance offrent du crédit pour le microdosage. À ce jour, plus de 1 000 agriculteurs – dont 30 % sont des femmes – ont reçu une formation en microdosage ...

  19. Traumatic rupture of the diaphragm | Jamabo | Sahel Medical Journal

    African Journals Online (AJOL)

    Those treated for traumatic rupture of the diaphragm were selected and analyzed for age, gender, cause of injury, associated injuries sustained and mode of treatment. ... There were associated injuries in all cases and they involved the spleen, rib fractures, liver and lungs. ... Keywords: blunt trauma, diaphragmatic rupture

  20. Spatiotemporal variability in carbon exchange fluxes across the Sahel

    DEFF Research Database (Denmark)

    Tagesson, Håkan Torbern; Fensholt, Rasmus; Cappelaere, Bernard

    2016-01-01

    Semi-arid regions play an increasingly important role as a sink within the global carbon (C) cycle and is the main biome driving inter-annual variability in carbon dioxide (CO2) uptake by terrestrial ecosystems. This indicates the need for detailed studies of spatiotemporal variability in C cycling...

  1. Desertification in the Sahel: a reinterpretation of a reinterpretation

    CSIR Research Space (South Africa)

    Prince, SD

    2007-07-01

    Full Text Available In semiarid regions the ratio of annual net primary production to precipitation, rain-use efficiency (RUE), has been used as an index of desertification. In a recent publication (Hein & de Ridder, 2006) it was proposed that an incorrect...

  2. Sahel Medical Journal - Vol 5, No 4 (2002)

    African Journals Online (AJOL)

    Prevalence of Yersinia enterocolitica Among Diarrhoeal Patients Attending University of Benin Teaching Hospital Benin City, Nigeria · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. AI Omoigberale, PO Abiodun, 182-185. http://dx.doi.org/10.4314/smj2.v5i4.12825 ...

  3. A cyber shepherd at work in the Sahel | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-02-07

    Feb 7, 2011 ... Food for the soil: Rock phosphate as fertilizer. If you're a subsistence farmer in sub-Saharan Africa, you probably don't have much extra mo. View moreFood for the soil: Rock phosphate as fertilizer ...

  4. Day and night grazing by cattle in the Sahel

    NARCIS (Netherlands)

    Ayantunde, A.A.; Fernandez-Rivera, S.; Hiernaux, P.H.; Keulen, van H.; Udo, H.M.J.

    2002-01-01

    The influence of night grazing on feeding behavior, nutrition and performance of cattle was studied. Twenty-four steers weighing 367 kg (SD = 76) grazed either from 0900 to 1900 (day grazers), 2100 to 0700 (night grazers) or 0900 to 1900 and 2400 to 0400 (day-and-night grazers) during 13 weeks. Four

  5. Alcoholism and bone growth: A literary appraisal | Adebisi | Sahel ...

    African Journals Online (AJOL)

    Alcoholic preparations is one of the ingredients present in beverages, drugs or chemicals in common use even at pregnancy; and this is well acclaimed to be toxic to the conceptuses, particularly, the developing skeletal tissues. A thorough literature search at MEDLINE and consultation with local scientific publications, and ...

  6. Variability of aerosol vertical distribution in the Sahel

    Directory of Open Access Journals (Sweden)

    O. Cavalieri

    2010-12-01

    Full Text Available In this work, we have studied the seasonal and inter-annual variability of the aerosol vertical distribution over Sahelian Africa for the years 2006, 2007 and 2008, characterizing the different kind of aerosols present in the atmosphere in terms of their optical properties observed by ground-based and satellite instruments, and their sources searched for by using trajectory analysis. This study combines data acquired by three ground-based micro lidar systems located in Banizoumbou (Niger, Cinzana (Mali and M'Bour (Senegal in the framework of the African Monsoon Multidisciplinary Analysis (AMMA, by the AEROsol RObotic NETwork (AERONET sun-photometers and by the space-based Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP onboard the CALIPSO satellite (Cloud-Aerosol Lidar and Infrared Pathfinder Observations.

    During winter, the lower levels air masses arriving in the Sahelian region come mainly from North, North-West and from the Atlantic area, while in the upper troposphere air flow generally originates from West Africa, crossing a region characterized by the presence of large biomass burning sources. The sites of Cinzana, Banizoumbou and M'Bour, along a transect of aerosol transport from East to West, are in fact under the influence of tropical biomass burning aerosol emission during the dry season, as revealed by the seasonal pattern of the aerosol optical properties, and by back-trajectory studies.

    Aerosol produced by biomass burning are observed mainly during the dry season and are confined in the upper layers of the atmosphere. This is particularly evident for 2006, which was characterized by a large presence of biomass burning aerosols in all the three sites.

    Biomass burning aerosol is also observed during spring when air masses originating from North and East Africa pass over sparse biomass burning sources, and during summer when biomass burning aerosol is transported from the southern part of the continent by the monsoon flow.

    During summer months, the entire Sahelian region is under the influence of Saharan dust aerosols: the air masses in low levels arrive from West Africa crossing the Sahara desert or from the Southern Hemisphere crossing the Guinea Gulf while in the upper layers air masses still originate from North, North-East. The maximum of the desert dust activity is observed in this period which is characterized by large AOD (above 0.2 and backscattering values. It also corresponds to a maximum in the extension of the aerosol vertical distribution (up to 6 km of altitude. In correspondence, a progressive cleaning up of the lowermost layers of the atmosphere is occurring, especially evident in the Banizoumbou and Cinzana sites.

    Summer is in fact characterized by extensive and fast convective phenomena.

    Lidar profiles show at times large dust events loading the atmosphere with aerosol from the ground up to 6 km of altitude. These events are characterized by large total attenuated backscattering values, and alternate with very clear profiles, sometimes separated by only a few hours, indicative of fast removal processes occurring, likely due to intense convective and rain activity.

    The inter-annual variability in the three year monitoring period is not very significant. An analysis of the aerosol transport pathways, aiming at detecting the main source regions, revealed that air originated from the Saharan desert is present all year long and it is observed in the lower levels of the atmosphere at the beginning and at the end of the year. In the central part of the year it extends upward and the lower levels are less affected by air masses from Saharan desert when the monsoon flow carries air from the Guinea Gulf and the Southern Hemisphere inland.

  7. Childhood Fall from Heights in Sokoto, Nigeria. | MUNGADI | Sahel ...

    African Journals Online (AJOL)

    ... commonest trauma was head injury seen in 36 patients (55.4%) and was responsible for the overall mortality of 6.8% (4 cases). Extremity fractures occurred in 18 patients (27.7%) and limb lost was recorded in 5 patients (8.5%). The biomechanics of fall, the peculiarities of fall from height in this environment and preventive ...

  8. Quantifying Livestock Heat Stress Impacts in the Sahel

    Science.gov (United States)

    Broman, D.; Rajagopalan, B.; Hopson, T. M.

    2014-12-01

    Livestock heat stress, especially in regions of the developing world with limited adaptive capacity, has a largely unquantified impact on food supply. Though dominated by ambient air temperature, relative humidity, wind speed, and solar radiation all affect heat stress, which can decrease livestock growth, milk production, reproduction rates, and mortality. Indices like the thermal-humidity index (THI) are used to quantify the heat stress experienced from climate variables. Livestock experience differing impacts at different index critical thresholds that are empirically determined and specific to species and breed. This lack of understanding has been highlighted in several studies with a limited knowledge of the critical thresholds of heat stress in native livestock breeds, as well as the current and future impact of heat stress,. As adaptation and mitigation strategies to climate change depend on a solid quantitative foundation, this knowledge gap has limited such efforts. To address the lack of study, we have investigated heat stress impacts in the pastoral system of Sub-Saharan West Africa. We used a stochastic weather generator to quantify both the historic and future variability of heat stress. This approach models temperature, relative humidity, and precipitation, the climate variables controlling heat stress. Incorporating large-scale climate as covariates into this framework provides a better historical fit and allows us to include future CMIP5 GCM projections to examine the climate change impacts on heat stress. Health and production data allow us to examine the influence of this variability on livestock directly, and are considered in conjunction with the confounding impacts of fodder and water access. This understanding provides useful information to decision makers looking to mitigate the impacts of climate change and can provide useful seasonal forecasts of heat stress risk. A comparison of the current and future heat stress conditions based on climate variables for West Africa will be presented, An assessment of current and future risk was obtained by linking climatic heat stress to cattle health and production. Seasonal forecasts of heat stress are also provided by modeling the heat stress climate variables using persistent large-scale climate features.

  9. Improving Shaping Efforts in Africa’s Maghreb and Sahel

    Science.gov (United States)

    2011-03-21

    9·Jenny Booth, "Al-Qaeda kills British hostage Edwin Dyer; kidnapped in Mali after music festival ," Times Online, June 3, 2009, http://www. times...34Al-Qaeda kills British hostage Edwin Dyer, kidnapped in Mali after music festivaL " Times Online, June 3, 2009, http://www.timesonline.co.uk/tol...Khadafi ~md his Libyan regime. Without. the support of the international co~ unity and the United States; fledgling democracies incapable of or

  10. Vegetation Change, Tree Diversity and Food Security in the Sahel

    DEFF Research Database (Denmark)

    Sambou, Antoine

    was found in forest than other landscape elements. In contrast, tree richness was higher in croplands in Boly Serere and Poukham Tock. Factors such as land-use, soil salinity and pH had significant effects on vegetation parameters. Local people had observed a general decline of woody plants....... This was confirmed by satellite imagery analysis. Satellite images showed losses tree cover and mangrove, and an increase in shrub and herbaceous covers and tans. Human activities and environmental factors (especially salinization) appear to be the main drivers of vegetation change. Overall, the vegetation change...

  11. Scenarios on future land changes in the West African Sahel

    DEFF Research Database (Denmark)

    Lambin, Eric; D'haen, Sarah Ann Lise; Mertz, Ole

    2014-01-01

    In an attempt to anticipate possible futures of drylands of West Africa in the face of rapid socio-economic and environmental changes, we developed four scenarios based on recent survey data, the literature and our knowledge of the region. The four scenarios are inspired by those developed...

  12. Irrigation et intensification de la production agricole au Sahel ...

    African Journals Online (AJOL)

    Sept sources de fourniture de semences ont été identifiées tandis que près de trente contraintes sont signalées sur les variétés (P<0,001). Les plus importantes sont la faible résistance aux maladies, l'exigence des variétés en engrais et le faible niveau de rendement. Conclusion et application des résultats: L'état de la ...

  13. Testicular and related size evaluations in Nigerian Sahel goats with ...

    African Journals Online (AJOL)

    A stratified quota sample population of 125 male goats inclusive of all testicular sizes was taken at a slaughterhouse in Maiduguri, Nigeria. The bucks were aged 18-30 months and weighed 17.04 ± 2.99 (12-25) kg. Body, testicular and epididymal weights of each goat with other related size measurements were estimated.

  14. Glycaemic Index Of Boiled Cocoyam And Stew | Alegbejo | Sahel ...

    African Journals Online (AJOL)

    Cocoyam can be processed in several ways. It contains digestible starch, protein and other valuable nutrients. Consumption of cocoyam is very high all over Nigeria. This study was undertaken to determine the glycaemic response of diabetic and healthy subjects to equal amounts of carbohydrate in the form of boiled ...

  15. Pattern of Blood Pressure in Adolescents | Mijinyawa | Sahel ...

    African Journals Online (AJOL)

    Background: Out of office blood pressure has been shown to be a better representation of an individual's blood pressure. This prospective ... The prevalence of hypertension and the relationship between blood pressure level and height, body mass index, age and socio-economic status were determined. Results: The mean ...

  16. Rural flour mills. farmer promotion tool m the Sahel area

    Directory of Open Access Journals (Sweden)

    Audroing, M.

    1993-01-01

    Full Text Available The Grameen Bank is a specialized financial institution in Bangladesh that was established to provide credit to the rural poor for the purpose of improving their economic conditions with the hypothesis that if the poor are supplied with working capital they can generate productive self-employment without external assistance. Loans from the Grameen Bank are used primarily for undertaking noncrop activities. The loan repayment performance is excellent. Only 0.5 percent of loans to 975 borrowers surveyed were overdue beyond one year, and overdue weekly installments (before the expiration of the one-year repayment period were only 3.3 percent of the total amount borrowed. The Grameen Bank concept of credit without collateral should work in other countries with widespread poverty and underemployment. But elements like taking the bank to the people and intensive interaction of bank staff with borrowers may be inappropriate and highly expensive for sparsely settled areas with underdeveloped transport systems. For such environments, an appropriate delivery mechanism has to be worked out.

  17. Evaluating U.S. and EU Trans Sahel Policies

    Science.gov (United States)

    2013-03-01

    Colleges and Schools, 3624 Market Street, Philadelphia, PA 19104, (215) 662-5606. The Commission on Higher Education is an institutional accrediting...Education of the Middle States Association of Colleges and Schools, 3624 Market Street, Philadelphia, PA 19104, (215) 662-5606. The Commission on Higher...Saharan forest region. It stretches from West Africa to the Red Sea, extending through Burkina Faso, Cape Verde , Chad, Gambia, Guinea Bissau, Mali

  18. Sahel Journal of Veterinary Sciences - Vol 8, No 2 (2009)

    African Journals Online (AJOL)

    Evolution, Clonality and Some Virulence Characteristics of Enterohaemorrhagic Escherichia coli (EHEC): An Update · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. J.A Musa, H.K Kazeem, M.A Raji, N.M Useh ...

  19. Recent dynamic change of the tributaries of the Niger river in Sahel

    Science.gov (United States)

    Mamadou, I.; Descroix, L.; Costard Gautier, E.; Brunstein, D.; Le-Breton, E.; Bouzou Moussa, I.; Faran Maiga, O.; Abba, B.; Malam Abdou, M.; Yero Souley, K.

    2009-04-01

    In the region of Niamey (Niger), the Niger river is subjected to recent important morphodynamic changes, because of the increasing activity of numerous tributaries ("koris", haoussa term for oued). These seasonal tributaries, recently formed, are responsible of an important increase of the sediment supply in the Niger river near Niamey (Niger), they provoke an important sedimentation in the river bed. The first aim of this study is to highlight the koris evolution and its impact on the Niger river. The second part of the study consists of the determination of factors explaining this recent evolution. External factors (mainly rainfall frequency and intensity ) and human impacts (mainly land use changes) are investigated. Different methods are carried out at different spatial and temporal scales: i) water and sediment measurements are conducted during the floods in the koris; precise topographic surveys allow the quantification of the sediment remobilisation in the kori bed and on their alluvial fan; ii) A rainfall statistical study is also realized to determine the possibility of an increase in extreme rainfall events; iii) at the koris basin scale, on the basis of aerial pictures and satellite images, diachronic analyses are conducted to determine the evolution of the landscape. It appears that the main factor is the soil use change. In the 1950's cultivated areas represented 10% of the Sahelian territory. Today, those areas are almost entirely cultivated. In the koris basin, these changes generate runoff and soil loss increases. Keywords: Niamey region; endoreic; koris; Niger river; human impacts: extreme rainfall events; soil use change

  20. Les TIC au secours des éleveurs du Sahel | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    information disponible sur le Web : un équipement complet pour la connexion Internet a été installé dans chaque unité pastorale, pour leur permettre d'être informés en temps réel à travers un site construit pour eux en juillet 2003.

  1. Inter-Decadal Nature of Rainfall Character Over Sudano-Sahel ...

    African Journals Online (AJOL)

    The study investigated the spatial pattern of decadal variations in annual rainfall amounts in the Sokoto-Rima River Basin, Northwestern Nigeria. Rainfall dataset which is available on high-resolution (0.5 x 0.5 degree) grids resolution from the Climatic Research Unit CRU TS 3.21 of the University of East Anglia, Norwich, ...

  2. Les TIC au secours des éleveurs du Sahel | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    7 févr. 2011 ... L'élevage transhumant constitue donc un élément capital du secteur primaire au Sénégal, où il procure aux ruraux de 55 à 75 % de leurs revenus. ... qu'une estimation de la « capacité de charge », indiquant le nombre d'animaux pouvant migrer sans grand risque pour l'environnement et les ressources.

  3. Biometry of the ovary in Balami, Yankassa sheep and Sahel goat ...

    African Journals Online (AJOL)

    A Aliyu, I.D. Peter, M Zakariah, V.A. Maina, K.D. Malgwi, A.A. Bitrus. Abstract. No Abstract. Keywords: biometry, goat, sheep, reproduction, ovary, follicles. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

  4. [Evaluation of mothers' knowledge in pre- and postnatal preventive care in the Tunisian Sahel].

    Science.gov (United States)

    Soltani, M S; Sakouhi, M; Belguith, Z; Ben Salem, K; Gacem, H; Bchir, A

    1999-06-01

    Maternal and child health is one of the major concerns of public health throughout the world. Health education and increased knowledge of mothers in relation to their health is a strategy of choice adopted in many countries for improving maternal and child health. It is within this framework that this action is being carried out, which aims to evaluate the knowledge of mothers in the area of preventive care for women. A cross-sectional survey was carried out among 915 parturient women from the Monastir region (coastal region of Tunisia) at the time of delivery, between May 1 and July 26, 1996. The survey was based on a questionnaire that explores, in addition to the socio-demographic characteristics of parents, the level of surveillance during pregnancy and mothers' knowledge in relation to preventive care of women. The majority of women (95%) are aware of the importance of prenatal surveillance, yet 12% don't have any knowledge of the recommended number of prenatal visits. Concerning contraception, the tetanus vaccination and the post-natal consultation, knowledge concerning their importance is high, but practice in these areas is not. Roughly only 1/3 of mothers used contraception before their current pregnancies, and only 70% had both doses of the tetanus vaccination. Health education on preventive care received by the mothers helps increase knowledge and probably practices as well. The increase in mothers' knowledge happens with appropriate initial and continued training in health education, provided by health professionals and with the reinforcement of educational activities during each contact with the mother both during her pregnancy and in periods where she isn't pregnant.

  5. Communications Channels in the Sahel Using Mauritania, Mali, Niger, and Chad as a Case Study

    Science.gov (United States)

    2007-05-01

    ethnology at the Smithsonian National Museum of Natural History. As one of Mali’s biggest exports, music is often full of social messages like women’s...Upon approving the exhibit, Dr. Mary Jo Arnoldi, curator of African ethnology at the museum, wrote in a letter to Davis: "When I looked through the

  6. state of sorghum downy mildew in maize in the sudan and sahel ...

    African Journals Online (AJOL)

    DR. AMINU

    2010-06-01

    Jun 1, 2010 ... Singh,S.D.,J.P.Wilson,S.S.Navi,B.S.Talukdar,D.E.,Hess and. Reddy,K.N.(1997) Screening Technique and. Sources of Resistance to Downy Mildew and Rust in Pearl Millet. Information Bulletin No. 48.Icrisat,. Patancheru 502 324 Andrapradesh. India. Tantere,D.M.(1975) Cultural practices to decrease ...

  7. In Harmony with the Population: Ethnomusicology as a Framework for Countering Violent Extremism in the Sahel

    Science.gov (United States)

    2016-12-01

    1 Andy Morgan, Music, Culture and Conflict in Mali ( Copenhagen : Freemuse, 2013), 53. 2 Joshua Hammer, “When the...strictly interpreting Islamic law and exacting harsh revenge on those who did not support the GIA or its values. In addition to targeting locals...who interpret media and put it into relevant context for the community. In the two-step model then, most participants are not directly influenced

  8. USSOF OPERATIONS IN AFRICA: PROSPECTS FOR FUTURE ENGAGEMENTS IN THE SAHEL

    Science.gov (United States)

    2017-04-03

    the world.2 Meanwhile, the US Special Operations Command (USSOCOM) and the Central Intelligence Agency (CIA) continue to use drones and raids in...building capacity, capability, trust and interoperability between USSOF and local military forces.32 USSOF also employs RPA drones , but are limited to...USSOF could conduct precision strikes against VEOs using drones , provide additional combat force protection equipment (MRAPs) with 12.7mm guns to boost

  9. Methane recovery by anaerobic digestion of cellulosic materials available in Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Mahamat, A.Y. (Faculte des Sciences Exactes et Appliquees, Departement de Chimie, N' Djamena-Farcha, Republic of Chad); Gourdon, R.; Leger, P.; Vermande, P. (Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (FR). Lab. de Chimie Physique Appliquee et Environnement)

    1989-01-01

    Seventy-day anaerobic batch digestions were carried out at 35{sup 0}C in 100 ml glass vials in order to determine the methane potentials of four cellulosic materials available in developing countries. The substrates were millet bran and millet straw which were tested in N'Djamena (Republic of Chad), Calotropis procera leaves which were tested in Lyon (France), and brewing draffs from Moundou's brewery (Republic of Chad) which were investigated both in N'Djamena and Lyon so as to control data reproducibility. All substrates were broken into small pieces, except millet bran which was already in the appropriate form. The four substrates tested are suitable for methane recovery providing that pH is controlled by the addition of alkali in the case of millet bran digestion. (author).

  10. Regional Security Cooperation in the Maghreb and Sahel: Algeria’s Pivotal Ambivalence

    Science.gov (United States)

    2012-02-01

    profile abduc- tions, in turn, threaten vital tourism and economic investments, such as the Trans-Sahara Gas Pipeline intended to transport Nigerian gas...Laurence Aïda Ammour, La Mauritanie au carrefour des menaces régionales, Notes Internacionals No. 19, ( Barcelona : Bar- celona Centre for

  11. Droit des femmes à l'eau à usage agricole au Sahel (Mauritanie ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    RADI) de déterminer les modalités et la qualité d'accès et du contrôle des femmes sur l'eau à usage agricole dans les trois pays ciblés. Les résultats de la recherche seront utilisés pour le renforcement de la capacité des organisations féminines et ...

  12. A solar oven in the aim of reducing wood consumption in the Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Ba, A.; Hamadou, A. [Centre National d' Energie Solaire, Niamey (Nigeria); Saley, H.A. [UDUS, Sokoto (Niger)

    2004-07-01

    01 Traditional ovens working with large amount of wood are used by butchers to roast mutton in Niger. As we know, this country is mostly occupied by Sahara desert. It is quite important to preserve its forest and all initiative to reduce wood consumption is welcome. That is one of the reasons that a solar oven is conceived. It is a hot box type solar cooker that has parallelepiped form with 1200 mm length, 975 mm width, and 755 mm height, the all with four rollers feet. The absorber is half cylinder, constituted with a black-painted sheet and with 1100 mm length and 965 mm diameter. The oven has a double glass cover and two reflectors permitting the increase of solar radiation in the box. The external wall is constituted of wood board on which a layer of varnish has been putted. Between the board and the absorber there is a glass wool insulation of 25 mm thickness. Tests have been run to characterise the oven: -temperature profile in the box (from the bottom to the glass cover) -efficiency of the cooker calculated - economic aspects examined. (orig.)

  13. Le djihadisme au Sahel: enjeux et perspectives | Namaïwa | Africa ...

    African Journals Online (AJOL)

    The second is the inadequacies of democratic governance, the soil on which jihadists base themselves to have sympathies among the popular masses, whom they transform into actors or instruments. And the third identifies five avenues of reflection and action to combat this phenomenon which has to become globalized.

  14. Services financiers et déploiement d'innovations agricoles au Sahel ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au cours des vingt dernières années, plusieurs innovations visant à améliorer les rendements des cultures vivrières ont été développées dans les centres de recherche agronomique d'Afrique de l'Ouest et par les chercheurs de la communauté internationale. Si elles étaient adoptées, plusieurs de ces innovations ...

  15. Klimaændring, ørkendannelse og konflikt i Sahel

    DEFF Research Database (Denmark)

    Rasmussen, Kjeld; Wæver, Ole

    2013-01-01

    Årsagssammenhænge ved nuværende begrænsede temperaturstigninger er svære at efterspore, og der er ikke grundlag for at fremmane et billede af et stadig stigende konfliktniveau og krige i regionen af klimagrunde....

  16. Ecological sanitation products reuse for agriculture in Sahel: effects on soil properties

    Science.gov (United States)

    Sangare, D.; Sawadogo, B.; Sou/Dakoure, M.; Ouedraogo, D. M. S.; Hijikata, N.; Yacouba, H.; Bonzi, M.; Coulibaly, L.

    2015-03-01

    The sanitary products (i.e toilet compost, urine, and greywater) from resource oriented sanitation are a low-cost alternative to chemical fertilizers and irrigation water for poor communities in dry areas. However, if these products are not managed carefully, increased soil salinity and sodium accumulation could occur. The aim of this study was to assess the effects of these products at different combinations on the properties of cultivated soil and on okra plant productivity. The treatments were: (1) fresh dam water (FDW) as a negative control, (2) FDW plus chemical fertilizer (i.e.NPK) (FDW + NPK) as a positive control, (3) treated greywater (TGW), (4) FDW plus Urine/Toilet Compost (UTC) (FDW + UTC), (5) TGW + UTC, (6) TGW + NPK. Effects on okra productivity were assessed by measuring the fresh fruit yield whereas effects on soil were evaluated through measurements of electrical conductivity (EC), sodium adsorption ratio (SAR) and total organic carbon (TOC) at various depths. Results showed that the yields obtained with TGW (0.71 t ha-1) and TGW + UTC (0.67 t ha-1) were significantly higher than the yields obtained with the positive control FDW + NPK (0.22 t ha-1) meaning that the fertilizer value of the sanitary products was higher than that of chemical fertilizer. Concerning effects on soil, SAR values increased significantly in plots treated by TGW (8.86 ± 1.52) and TGW + UTC (10.55 ± 1.85) compared to plots fertilized with FDW (5.61 ± 1.45) and FDW + NPK (2.71 ± 0.67). The TOC of plots treated with TGW + UTC (6.09 ± 0.99 g kg-1) was significantly higher than those of FDW + NPK (4.46 ± 0.22 g kg-1). Combined sanitary products from resource oriented sanitation can be reused as a nutrient source and water for food production, provided that soil salinity is monitored and the soil has high drainage capacity.

  17. The biological and physical role of mulch in the rehabilitation of custed soil in the Sahel

    NARCIS (Netherlands)

    Mando, A.; Stroosnijder, L.

    1999-01-01

    During three consecutive years (1993–1995) a split-plot design with three replications was used to study the biological and physical role of mulch in the improvement of crusted soil water balance and its productivity in the north of Burkina Faso. The main treatment was the use of an insecticide, to

  18. Ecology and management of charcoal rot (Macrophomina phaseolina) on cowpea in the Sahel

    NARCIS (Netherlands)

    Ndiaye, M.

    2007-01-01

    Keywords: Senegal/Niger/rotation/millet/isolate characterization/fonio/compost amendment / bioagent/ Clonostachysrosea /solarizationCowpea ( Vignaunguiculata Walp.) is the most important pulse crop in

  19. Analytical Tools for the Application of Operational Culture: A Case Study in the Trans-Sahel

    Science.gov (United States)

    2011-03-28

    Mauritania 17 Environment Area: 1,030,070 sq. km. (419,212 sq. mi.); slightly larger than Texas and New Mexico combined. Cities (2004...Products--livestock, traditional fisheries, millet, maize , wheat, dates, rice. Industry (47% of GDP 2007): Types--mining, commercial fishing. Services

  20. Dust and epidemic meningitis in the Sahel: A public health and operational research perspective

    Science.gov (United States)

    Thomson, M. C.; Jeanne, I.; Djingarey, M.

    2009-03-01

    Now that the health communities attention is increasingly focused on climate-health interactions, it has become essential for health decision makers to better understand the role that climate plays in driving disease burdens and health outcomes (both now and in the future) and the opportunity for integrating climate knowledge and information into health decision-making processes to mitigate the negative and strengthen the positive of climate-health interactions. Here we explore the potential climatic indicators and the climate information needs of relevance to the meningitis prevention and control community engaged in the African 'meningitis belt'.

  1. Dust and epidemic meningitis in the Sahel: A public health and operational research perspective

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, M C [International Research Institute for Climate and Society, Palisades, NY (United States); Jeanne, I [CERMES/Reseau International des Instituts Pasteur, BP 10 887 Niamey (Niger); Djingarey, M [WHO-Multi-Disease Surveillance Centre, Ougadougou (Burkina Faso)], E-mail: mthomson@iri.columbia.edu

    2009-03-01

    Now that the health communities attention is increasingly focused on climate-health interactions, it has become essential for health decision makers to better understand the role that climate plays in driving disease burdens and health outcomes (both now and in the future) and the opportunity for integrating climate knowledge and information into health decision-making processes to mitigate the negative and strengthen the positive of climate-health interactions. Here we explore the potential climatic indicators and the climate information needs of relevance to the meningitis prevention and control community engaged in the African 'meningitis belt'.

  2. Agricultural Production Monitoring in the Sahel Using Remote Sensing: Present Possibilities and Research Needs

    Science.gov (United States)

    1993-01-01

    surface temperature); and (6) instantaneous rates associated with the activity of the vegetation (rates of photosynthesis, transpi- ration, carbon ...Utilisation des Images. Bilan . Resultats, pp. 407 414. Paris, France. Ritchie. J. T. (1985). The Ceres-maize model. In CERES-MAIZE. A Simulation Model

  3. Variability in boundary layer structure during HAPEX-Sahel wet-dry season transition

    NARCIS (Netherlands)

    Wai, M.M.K.; Smith, E.A.; Bessemoulin, P.; Culf, A.D.; Dolman, A.J.; Lebel, T.

    1997-01-01

    The variability of the Sahelian boundary layer has been studied with streamline analyses, rainfall measurements, and upper air soundings during its transition from wet to dry season. The 1992 rainy season ended prematurely because of the early arrival of westerly troughs over West Africa. The change

  4. Calculating crop water requirement satisfaction in the West Africa Sahel with remotely sensed soil moisture

    Science.gov (United States)

    McNally, Amy; Gregory J. Husak,; Molly Brown,; Carroll, Mark L.; Funk, Christopher C.; Soni Yatheendradas,; Kristi Arsenault,; Christa Peters-Lidard,; Verdin, James

    2015-01-01

    The Soil Moisture Active Passive (SMAP) mission will provide soil moisture data with unprecedented accuracy, resolution, and coverage, enabling models to better track agricultural drought and estimate yields. In turn, this information can be used to shape policy related to food and water from commodity markets to humanitarian relief efforts. New data alone, however, do not translate to improvements in drought and yield forecasts. New tools will be needed to transform SMAP data into agriculturally meaningful products. The objective of this study is to evaluate the possibility and efficiency of replacing the rainfall-derived soil moisture component of a crop water stress index with SMAP data. The approach is demonstrated with 0.1°-resolution, ~10-day microwave soil moisture from the European Space Agency and simulated soil moisture from the Famine Early Warning Systems Network Land Data Assimilation System. Over a West Africa domain, the approach is evaluated by comparing the different soil moisture estimates and their resulting Water Requirement Satisfaction Index values from 2000 to 2010. This study highlights how the ensemble of indices performs during wet versus dry years, over different land-cover types, and the correlation with national-level millet yields. The new approach is a feasible and useful way to quantitatively assess how satellite-derived rainfall and soil moisture track agricultural water deficits. Given the importance of soil moisture in many applications, ranging from agriculture to public health to fire, this study should inspire other modeling communities to reformulate existing tools to take advantage of SMAP data.

  5. Dune ages in the sand deserts of the southern Sahara and Sahel

    Science.gov (United States)

    Bristow, Charlie; Armitage, Simon

    2015-04-01

    In this paper we aim to document the history of aeolian processes within the southern Sahara as part of the INQUA Dune Atlas. We review available luminescence ages for sand dunes across the southern Sahara and attempt to correlate periods of sand accumulation and to develop an improved understanding of the dune chronology on a regional basis. This was achieved by analysing dune age by country, as well as by latitude and longitude. The results show a very patchy spatial distribution of dune ages with large gaps that encompass some of the largest sand seas. Despite these gaps, some related patterns in dune morphology and stratigraphy appear to be consistent between northern Nigeria and southern Mali where older linear dunes are distinct from younger Late Holocene transverse and barchanoid dunes. Elsewhere in Mauretania linear dunes with different orientations appear to have accumulated at different times, most likely in response to changes in atmospheric circulation. Regional climatic changes are identified where dunes are transgressed by lake deposits within endorehic basins. We identify four locations where dune accumulation is terminated by lacustrine transgressions, two of which, in Lake Chad and the Bodélé Depression, occur shortly after the last glacial maximum (LGM). The third example at Gobiero in Niger occurred later, in the early Holocene, around 8.4 ka and a fourth marks a later transgression of Palaeolake MegaChad after 4.7 ka. Larger-scale latitudinal and longitudinal distributions in dune ages across the southern Sahara do not show any consistent patterns, though this may due to the small sample size relative to the study area. In addition, local variations in external controls such as wind regime, rainfall, vegetation and sand supply need to be considered, sometimes on a site by site basis. Limiting the analysis to dune ages determined using the single-aliquot regenerative-dose (SAR) protocol indicates a lack of dune preservation during the LGM and the Younger Dryas, times associated with increased dust input to the oceans which is assumed to indicate increased aeolian activity. The SAR dune dates suggest that preservation of dunes at the onset of succeeding humid intervals is an important component of the dune record. The most striking examples of this phenomenon occur where dunes are preserved within endorehic basins by lacustrine transgressions.

  6. Insecurity and Instability in the Sahel Region: The Case of Mali

    Science.gov (United States)

    2012-03-19

    is submitted in partial fulfillment of the requirements of the United States Army War College Diploma. The views expressed in this student academic ...student academic research paper are those of the author and do not reflect the official policy or position of the Department of the Army, Department...are characterized by procrastination . During the ten years of the Konaré’s regime, cash-based corruption has been the main policy adopted to manage

  7. Mokhtar Belmokhtar: One-Eyed Firebrand of North Africa and the Sahel

    Science.gov (United States)

    2015-02-01

    Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty...CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF PAGES 31 19a. NAME OF RESPONSIBLE PERSON a. REPORT...Arnaud Blin (Berkeley: University of California Press, 2007), 311–12. One can infer from later statements that Belmokhtar respected Hattab and may even

  8. Testicular sperm reserve of Sokoto red and Sahel bucks from Mubi ...

    African Journals Online (AJOL)

    The gonadal and epididymal sperm reserve were determined. The results revealed that, there were no significant differences (p>0.05) among variables RTSR, LTSR and PTSR for year 2008 and 2009. But significant (p<0.001) seasonal effect was observed, with early dry season having the highest values followed by late ...

  9. Siting guidelines for concentrating solar power plants in the Sahel: Case study of Burkina Faso

    Energy Technology Data Exchange (ETDEWEB)

    Azoumah, Y.; Tapsoba, G.; Thiam, S. [Laboratoire Energie Solaire et Economie d' Energie (LESEE), Fondation 2iE (International Institute of Water an Environmental Engineering), 01 BP 594, Ouagadougou 01 (Burkina Faso); Ramde, E.W. [Solar Energy Application Laboratory (SEAL), KNUST, Kumasi (Ghana)

    2010-08-15

    Selecting a site that meets the technical requirements for a concentrating solar power plant (CSP) is a very critical exercise. This paper points out crucial factors and provides guidelines regarding the selection of suitable sites. It especially focuses on Sahelian countries which have their own climatic peculiarities. These countries, characterized by low access to electricity, are well endowed in solar resources. They are potentially good locations for concentrating solar power plants since their mean daily solar radiation exceeds 5.5 kWh/m{sup 2}. CSP presents therefore, a good opportunity for them to increase in a sustainable manner, their energy supply. The guidelines developed in this paper are applied to Burkina Faso as a case study. (author)

  10. Indigenizing Civic Education in Africa: Experience in Madagascar and the Sahel

    Science.gov (United States)

    Antal, Carrie; Easton, Peter

    2009-01-01

    In Africa, as in many countries of the South, democratization is sometimes perceived as a process modeled upon outside--and specifically Northern--experience. Formal civic education programs in those countries arguably reflect the same bias and have not always been notably successful. Yet there are rich patterns of civic involvement and democratic…

  11. Lambing and neonatal behaviour of DjaUonke x Sahel crossbred ...

    African Journals Online (AJOL)

    Observations were made of the behaviour of lambs during lambing of 52 ewes. The parameters recorded were the time the lamb stood up after being born, number of attempts at standing, time the lamb sucked after standing and the number of attempts at sucking. The effects of age and parity of dam, and birth weight and ...

  12. A Palaearctic migratory raptor species tracks shifting prey availability within its wintering range in the Sahel

    NARCIS (Netherlands)

    Trierweiler, Christiane; Mullie, Wim C.; Drent, Rudi H.; Exo, Klaus-Michael; Komdeur, Jan; Bairlein, Franz; Harouna, Abdoulaye; de Bakker, Marinus; Koks, Ben J.

    Mid-winter movements of up to several hundreds of kilometres are typical for many migratory bird species wintering in Africa. Unpredictable temporary food concentrations are thought to result in random movements of such birds, whereas resightings and recoveries of marked birds suggest some degree of

  13. Fragmentation de l'espace et conflits d'usage au sahel : cas du ...

    African Journals Online (AJOL)

    agropastoralisme dans le bassin versant de Yakouta, l'occupation de l'espace connaît une forte modification donnant lieu à des conflits d'usage. L'objectif de cette recherche est d'analyser les mutations spatio-temporelles de l'occupation des terres dans le ...

  14. Social networks and the dynamics of soil and water conoservation in the Sahel

    NARCIS (Netherlands)

    Mazzucato, V.; Niemeijer, D.; Stroosnijder, L.; Röling, R.

    2001-01-01

    This paper presents the results of an integrated approach to the study of soil and water conservation in Burkina Faso and discusses the validity of some of the major assumptions that continue to shape soil and water conservation policies and interventions.

  15. Millet growth in windbreak-shielded fields in the Sahel : experiment and model

    NARCIS (Netherlands)

    Mayus, M.

    1998-01-01

    In the Sahelian zone, future food supply is insecure due to increasing land degradation. Wind erosion contributes significantly to impoverishment of the sandy soils, which are often loose and sparsely covered by vegetation for most of the year. At the onset of the growing season (May -

  16. Gestion spatio-temporelle de la soudure alimentaire dans le Sahel burkinabé

    OpenAIRE

    Janin, Pierre

    2004-01-01

    National audience; Les espaces sahéliens sont marqués par la récurrence et la diversité des problèmes alimentaires (disponibilités insuffisantes, aléatoires ou inaccessibles). Une des principales difficultés à laquelle sont confrontés chercheurs et décideurs consiste donc à caractériser la nature de ce risque dans le temps et dans l'espace et à mesurer la vulnérabilité réelle des Sahéliens à l'insécurité alimentaire. Compte tenu des faibles capacités d'intervention des Etats et des organismes...

  17. United States Counterterrorism Strategy In the Trans-Sahara and the Rise of Salafi-Jihadism In the Sahel

    Science.gov (United States)

    2015-09-01

    Mafia : How Powerful?,” Daily Independent, February 19, 2013. http://dailyindependentnig.com/2013/02/nigerian-governors- mafia -how-powerful/. 164 “Joint...Girls’ Abduction: Protest March in Abuja.” BBC News. April 30, 2014. http://www.bbc.com/news/world-africa-27216931. “Nigerian Governors’ Mafia : How...Powerful?” Daily Independent, February 19, 2013. http://dailyindependentnig.com/2013/02/nigerian-governors- mafia -how- powerful/. Nossiter, Adam

  18. Crop yield monitoring in the Sahel using root zone soil moisture anomalies derived from SMOS soil moisture data assimilation

    Science.gov (United States)

    Gibon, François; Pellarin, Thierry; Alhassane, Agali; Traoré, Seydou; Baron, Christian

    2017-04-01

    West Africa is greatly vulnerable, especially in terms of food sustainability. Mainly based on rainfed agriculture, the high variability of the rainy season strongly impacts the crop production driven by the soil water availability in the soil. To monitor this water availability, classical methods are based on daily precipitation measurements. However, the raingauge network suffers from the poor network density in Africa (1/10000km2). Alternatively, real-time satellite-derived precipitations can be used, but they are known to suffer from large uncertainties which produce significant error on crop yield estimations. The present study proposes to use root soil moisture rather than precipitation to evaluate crop yield variations. First, a local analysis of the spatiotemporal impact of water deficit on millet crop production in Niger was done, from in-situ soil moisture measurements (AMMA-CATCH/OZCAR (French Critical Zone exploration network)) and in-situ millet yield survey. Crop yield measurements were obtained for 10 villages located in the Niamey region from 2005 to 2012. The mean production (over 8 years) is 690 kg/ha, and ranges from 381 to 872 kg/ha during this period. Various statistical relationships based on soil moisture estimates were tested, and the most promising one (R>0.9) linked the 30-cm soil moisture anomalies from mid-August to mid-September (grain filling period) to the crop yield anomalies. Based on this local study, it was proposed to derive regional statistical relationships using 30-cm soil moisture maps over West Africa. The selected approach was to use a simple hydrological model, the Antecedent Precipitation Index (API), forced by real-time satellite-based precipitation (CMORPH, PERSIANN, TRMM3B42). To reduce uncertainties related to the quality of real-time rainfall satellite products, SMOS soil moisture measurements were assimilated into the API model through a Particular Filter algorithm. Then, obtained soil moisture anomalies were compared to 17 years of crop yield estimates from the FAOSTAT database (1998-2014). Results showed that the 30-cm soil moisture anomalies explained 89% of the crop yield variation in Niger, 72% in Burkina Faso, 82% in Mali and 84% in Senegal.

  19. Climate change, climate variability and adaptation options in smallholder cropping systems of the Sudano - Sahel region in West Africa

    NARCIS (Netherlands)

    Traore, B.

    2014-01-01

    Key words: crop production, maize, millet, sorghum, cotton, fertilizer, rainfall, temperature, APSIM, Mali,   In the Sudano-Sahelian zone of West Africa (SSWA) agricultural production remains the main source of livelihood for rural communities, providing employment to more than 60 percent of

  20. Migration of the Common Redstart (Phoenicurus phoenicurus): A Eurasian Songbird Wintering in Highly Seasonal Conditions in the West African Sahel

    National Research Council Canada - National Science Library

    Mikkel Willemoes Kristensen; Anders P. Tøttrup; Kasper Thorup

    2013-01-01

    .... Fall migration passed west of the Mediterranean Sea and along the northwest African coast before the birds made an abrupt change of direction at the southern edge of the Sahara toward the winter area...

  1. Gravity and InSAR remote sensing of groundwater usage in the Sahel and Horn of Africa

    Science.gov (United States)

    Neely, W.; Borsa, A. A.; Burney, J. A.; Devlin, K.

    2016-12-01

    Changes in the Earth's climatic systems influence agro-ecological conditions on local, regional, and global scales. With the world's highest population growth rate, sub-Saharan Africa faces particularly acute concerns regarding food security and resource management. Historical sources of surface water for agricultural production may become less reliable and/or limited with increased climate variability, and African countries have already begun to depend on more stable sources of groundwater. Expected increases in groundwater usage pose questions about the sustainability of current agricultural practices, which require new sources of information to answer. Due to the logistics and costs to implement in situ networks to monitor regional water security, current remote sensing missions offer an affordable alternative. The Gravity Recovery and Climate Experiment (GRACE) has proven to be effective in quantifying changes in terrestrial water storage (TWS) at the regional scale using near-monthly gravity measurements from orbit. Using over a decade of measurements, we estimate TWS anomalies in Niger and Ethiopia. These anomalies offer a proxy for hydrological stressing, indicating potential targets for additional analysis. We use independent, but complementary, estimates of surface displacements from Interferometric Synthetic Aperture Radar (InSAR) to provide information on local groundwater withdrawal. Using data from ESA's Sentinel 1 mission and JAXA's Advanced Land Observing Satellite (ALOS) missions, we characterize the surface deformation over the past decade in regions of active groundwater pumping using the Small Baseline Subset (SBAS) technique. In particular, we investigate ties of ground motion to known agricultural/industrial land usage near Niamey, Niger and Eastern Oromia, Ethiopia to better understand how human activity affects available groundwater resources.

  2. Assessment and limits of the existent seasonal forecasts as support for the decision making process in the Sahel

    Science.gov (United States)

    Bacci, Maurizio; Genesio, Lorenzo; di Vecchia, Andrea; Tarchiani, Vieri; Vignaroli, Patrizio

    2010-05-01

    The economy of West Africa sahelian countries is based on the primary sector and the population's food security is strictly linked to rainfed crops production. The sahelian countries constitute a belt from Senegal to Chad characterized by an unimodal rainfall distribution during the summer months. The rainfall spatial and time distribution are very variable: dry spells and shifts in the rainy season onset are very frequent. The famines that stroke the region in the past demonstrate that in these ecosystems drought represents a key factor for the food security. In particular, anomalies in precipitation amount and distribution represent the major cause of losses in rainfed agriculture. The early availability of information on the development of the rainy season is essential for decision makers to assess the level of risk in terms of spatial extension and intensity, to take consequent decision on the mobilization of national/international stocks and to provide information for farmers orienting their choices for risk reduction. Addressing these needs, since late 90's the scientific community begins to develop long term meteorological forecast models. Nowadays, despite the general awareness on their potential role in food crises prevention, seasonal forecasts are still under exploited at regional/national level. Indeed, the major constraints to their operational use are (i) the reduced skill in intercepting key aspects of the agricultural season such as starting and ending date and presence of dry spells, and (ii) the difficulty of decision makers of understanding and consequently handling the level of uncertainty of the predictive information. Today the growing demand for early information to support decision-making requires an improvement in the suitability of seasonal forecasts and in their tailoring to users. The aim of this paper is contributing to the scientific debate on Seasonal Forecast proposing possible orientations for models further development and the production of new outputs translating climate forecast in impact forecast. The paper provides an assessment of the existing seasonal forecast products available for West African and highlighting the relevance of information for decision-making process. Moreover, it underlines the actual limits of the seasonal forecast products and the improvements needed to achieve more useful information for the end-user. The operational framework is the Food Crises Prevention Calendar (CPC) , which characterizes the crisis level in order to identify the appropriate information for decision makers in terms of timing, content and format. The study intend to differentiate Regional and National needs, evidencing that working at different scales is not only a resolution problem.

  3. Methanic fermentation of Euphorbia tirucalli, a rich and renewable vegetal biomass of the Sahel and arid zones

    Energy Technology Data Exchange (ETDEWEB)

    Sow, D. [Dakar Univ. (Senegal); Depeyre, D.; Isambert, A. [Ecole Centrale des Arts et Manufactures, 92 - Chatenay-Malabry (France)

    1994-12-31

    A rich and renewable vegetal biomass is existing in Senegal. In fact Euphorbia tirucalli is a latex plant well adapted to sahelian climatic conditions, spread all along the country. In this work, methanic fermentation experimentations are made with this plant in a specific continuous fermentor named Transpaille. A 120 l biodigester was tested at 37 deg C with a piece-broken plant. The registered volumic efficiency is 0.80 l/l.d. With this interesting result, the same experiment was made with real operating conditions on a village digester in a farm. With a bioreactor of 12 m{sup 3}, incubated at ambient temperature, the obtained volumic efficiency is 0.61 l/l.d. The produced biogas of this experiment was used for food cooking and for farm milk cooling. This work shows that a vulgarization policy of the biogas way in rural conditions in Senegal is now possible with Euphorbia tirucalli. (authors). 19 refs., 6 figs., 2 tabs.

  4. Climate change, climate variability and adaptation options in smallholder cropping systems of the Sudano - Sahel region in West Africa

    NARCIS (Netherlands)

    Traore, B.

    2014-01-01

    In the Sudano-Sahelian zone of West Africa (SSWA) agricultural production remains the main source of livelihood for rural communities, providing employment to more than 60 percent of the population and contributing to about 30% of gross domestic product. Smallholder agricultural production is

  5. Modelling water erosion in the Sahel: application of a physically based soil erosion model in a gentle sloping environment

    NARCIS (Netherlands)

    Visser, S.M.; Sterk, G.; Karssenberg, D.

    2005-01-01

    Water is a major limiting factor in arid and semi-arid agriculture. In the Sahelian zone of Africa, it is not always the limited amount of annual rainfall that constrains crop production, but rather the proportion of rainfall that enters the root zone and becomes plant-available soil moisture.

  6. Dry Season Effect on Live Weight and some Body Dimensions of Working Donkeys in the Sudano-sahel Region of Cameroon

    Directory of Open Access Journals (Sweden)

    Ebangi, AL.

    2005-01-01

    Full Text Available Live weight (LW, heart girth (HG, trunk length (TL, body length (BL and height-at-withers (HW of 135 working donkeys, aged between two and 15 years, were monitored during the dry season of 1996 and 1997. This was to determine period(s of the dry season when feed supplementation and/or health care should be reinforced in preparation of high work demands during the rainy season. Variations in LW, HG, TL, BL, HW, HG:HW and TL:HW from start of the dry season to the start of the rainy season were highly significant (P< 0.001. Correlations between live weight and the other measures were positive and highly significant (P< 0.0001. Males showed weight gains between start of the cold-dry-season (CDS and start of the hot-dryseason (HDS. Weight gains in castrates were between start of the CDS and end of the HDS (April. Female donkeys maintained weight gains through out the dry season. Consequently, supplementation of castrates and males at the beginning (January and end (April of the HDS as to reinforce and maintain significant weight gains for maximize draught energy potential for rainy season work demands, is necessary. Where the female donkey express weight gain but poor bodied there will be need for supplementation in order to booster and enhance endurance. Also, estimates of HG, TL, BL, HW, HG:HW and TL:HW may be useful indicators for the selection of working donkeys as to optimize draft capacity and endurance for rainy season work demands.

  7. Applying the concept of “energy return on investment” to desert greening of the Sahara/Sahel using a global climate model

    NARCIS (Netherlands)

    Bowring, S.P.K.; Miller, L.M.; Ganzeveld, L.N.; Kleidon, A.

    2014-01-01

    Altering the large-scale dynamics of the Earth system through continual and deliberate human intervention now seems possible. In doing so, one should question the energetic sustainability of such interventions. Here, from the basis that a region might be unnaturally vegetated by employing

  8. Exploitation minière du cuivre dans la région de Nioro-du-Sahel (Mali) à l’époque des grands empires soudanais

    OpenAIRE

    Badey, Sylvain

    2016-01-01

    Introduction Le cuivre est présent massivement dans les sites archéologiques de l’Afrique de l’Ouest durant la période des grands empires soudanais. Les textes arabes et la caravane perdue du Ma’den Ijâfen découverte par Théodore Monod (Monod 1969) attestent que ce cuivre est parvenu du Maghreb massivement en Afrique subsaharienne par voies transsahariennes (fig. 1). Toutefois, les ressources en cuivre de cette région ont, elles aussi, été exploitées : la recherche archéologique menée par Ni...

  9. Remote sensing and geographic information systems to predict the density of ruminants, hosts of Rift Valley fever virus in the Sahel.

    Science.gov (United States)

    Pin-Diop, Raphaëlle; Touré, Ibra; Lancelot, Renaud; Ndiaye, Magatte; Chavernac, David

    2007-01-01

    Rift Valley fever (RVF) is an acute arboviral disease of domestic ungulates and humans in Africa and the Middle East. Since the first epidemic in 1987, Senegal has been confronted with recurrent episodes of the disease. This study aimed to model spatial distribution of ruminants in the agropastoral area of Barkedji (Senegal) where the disease is enzootic. In this Sahelian ecosystem, livestock distribution mainly depends on the availability of resources. Accordingly, remote sensing and geographic information systems (GIS) were used to seek environmental indicators of livestock density. A high-resolution Landsat image was associated with landscape field data to describe the land-cover. A series of normalized difference vegetation index values gave an estimation of the phytomass. In addition the compounds of herders in the study zone were located and sampled. Three surveys were conducted during the rainy season to record the number of herds in each compound of the sample. All these data were overlaid in the GIS. A discriminant analysis was performed to associate the observed herd density with environmental data and to develop a predictive model for the entire study zone. The final result was a 1-km resolution raster map of herd density during a normal rainy season.

  10. [The international man-media Tessékéré (OHMi) Observatory: a research tool to study the complexity of arid ecosystems in Sahel].

    Science.gov (United States)

    Guissé, Aliou; Boëtsch, Gilles; Ducourneau, Axel; Goffner, Deborah; Gueye, Lamine

    2013-01-01

    In the Sahelian zone, the drought phenomenon, combined with anthropic factors (monoculture, bush fires, defect or deficit of manure, overgrazing, etc.), has seriously affected ecological great balances, involving a degradation of the natural resources as well as a fall in agricultural productions, pointing to a process of desertification. To face these challenges, in the course of the 8th ordinary session of the conference of the Heads of States of the African Union held in January 2007 in Addis Ababa (Ethiopia), 11 countries adopted the Panafrican project called the Green Great Wall (GGW). The total objective of the GGW is to contribute i) to the fight against the desert's advance, ii) to the development of the Saharan-Sahelian zones toward a durable management of the natural resources, and iii) to the fight against poverty. It deals with the construction of a set of zones of afforestation crossing the whole African continent in the long term (7000km of which are in the west). Even if some decisions in the launching phase the GGW must be taken quickly, one cannot do without investment in interdisciplinary research. In particular, associating fundamental research and applied research will allow us to ensure the success in the medium and long term of such a large-scale reforestation project. Research segmented in compartmentalized knowledge fields needed to get adequate tools, among which OHMi Tessékéré, initiated by INNEE (Centre national de la recherche scientifique [CNRS]), in partnership with UCAD, constitutes an example. This suitable scientific tool, capable of action flexibility, of self-financing capacity, anchored in civil society, ready to implement a pragmatic and local interdisciplinarity founded currently on the concept of socio-ecological system (SES), is the one we chose to conduct our studies on the Ferlo arid ecosystems. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  11. Assessing Land Degradation/Recovery in the African Sahel from Long-Term Earth Observation Based Primary Productivity and Precipitation Relationships

    DEFF Research Database (Denmark)

    Fensholt, Rasmus; Rasmussen, Kjeld; Kaspersen, Per Skougaard

    2013-01-01

    Modeling and Mapping Studies 3rd generation (GIMMS3g)) over the year (ΣNDVI), and the blended EO/rain gauge based data-set for annual precipitation (Climate Prediction Center Merged Analysis of Precipitation, CMAP) results in RUE-estimates which are highly correlated with precipitation, rendering RUE...

  12. Des empires de l’âge d’or à la délicate mécanique des sociétés : histoire et archéologie du Sahel médiéval From golden-age empires to the complex clockwork of societies: history and archaeology of medieval Sahel

    Directory of Open Access Journals (Sweden)

    Thomas Vernet

    2013-06-01

    Full Text Available Dans les ouvrages de vulgarisation, les manuels d’histoire et, bien souvent, les publications académiques, l’Afrique de l’Ouest « médiévale » est invariablement convoquée pour démontrer la profondeur de l’histoire africaine et placer le continent sur la grande carte des civilisations anciennes du monde. Le Moyen Âge serait le temps des « grands empires », un âge d’or qui verrait la succession du Ghana, du Mali, puis du Songhay, les meilleurs représentants de cette « Afrique des siècles d’or »...

  13. Use of the tritium thermonuclear peak in the deep unsaturated zone for quantitative estimate of aquifer recharge under semi-arid conditions: first application in Sahel. La recherche du pic de tritium thermonucleaire en zone non saturee profonde sous climat semi-aride pour la mesure de la recharge des nappes: premiere application au Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Cheikh Becaye Gaye (Dakar Univ. (Senegal)); Aranyossy, J.F.

    1992-08-01

    The location of the bomb tritium signal at 20 and 12 m depth in the unsaturated sand dunes in the semi-arid part of North Senegal leads to a qualitative estimate of the effective infiltration of 22 and 26 mm.yr{sup -1}. These figures correspond respectively to 6.5 and 8% of the total precipitation since 1963. Tritium content distribution in interstitial water is modelled by convolution of the analytical solution of the dispersion equation. Best fitting of the complete 12 m depth tritium peak is obtained with a dispersion coefficient of 0.03 m{sup 2}.yr{sup -1}.

  14. Genetic diversity studies on selected rice varieties grown in Africa ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    three improved Sahel aromatic varieties, group 4 was the most diversified group with three sub-clusters and group 5 corresponded ... cooking and eating quality traits and aroma in rice breeding program. Key words: Grain quality, .... created by AfricaRice Sahel station, 15 improved Sahel varieties of different origins mostly ...

  15. Valorisation des résultats de recherches et des innovations au ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF). In the Sahel, agricultural production is strictly limited by drought and low soil fertility. View moreIntegrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF) ...

  16. Greed and Grievance: Economic Agendas in Civil Wars | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Natural Resources Management for Sustainable Food Security in the Sahel. The agricultural and pastoral production deficit combined with the general rise in food prices has increased food insecurity in the Sahel. View moreNatural Resources Management for Sustainable Food Security in the Sahel ...

  17. Groundwater influence on the aeolian sequence stratigraphy of the Mechertate-Chrita-Sidi El Hani system, Tunisian Sahel: Analogies to the wet-dry aeolian sequence stratigraphy at Meridiani Planum, Terby crater, and Gale crater, Mars

    Science.gov (United States)

    Essefi, Elhoucine; Komatsu, Goro; Fairén, Alberto G.; Chan, Marjorie A.; Yaich, Chokri

    2014-05-01

    A multidisciplinary study of the watershed and depressions of the Mechertate-Chrita-Sidi El Hani (MCSH) system in eastern Tunisia shows that groundwater upwelling and/or seepage toward the modern surface is important in the shaping of its geomorphologic features and sediment outcrops. Along the watershed of the system, groundwater is downward enriched with evaporitic minerals. These minerals precipitate as cement and protect the sediment outcrops from aeolian erosion. The water table is the limiting control on erosion and deposition, and also influences the succession of sediment along the system. The water table further determines the local base level, which controls the deposition within depressions. With increasing humidity at the limit of the capillary fringe, the landscape of the evaporative system is organized according to three sedimentary types: (1) unconsolidated sediment of aqueous and/or aeolian origin that is eroded and transported toward depressions (away from groundwater interactions), (2) consolidated sediment that is also aqueous and/or aeolian in origin and is protected from aeolian erosion by groundwater influence, and (3) sedimentary filling of depressions located within accumulation zones. These sediments are organized along a lateral, basinward profile. Here we show that during periods of relative water table fall, sediments from the watershed prograde to cover the sabkha basin fill. The rise and fall of the water table and the connected base level result in the deposition of genetically-related progradational and retrogradational sequences. We propose that these genetic sequences can be useful to interpret the sequence stratigraphy at three locations on Mars where sedimentary formations were probably controlled by direct groundwater influence: Meridiani Planum, Terby crater, and Gale crater. At Meridiani Planum, the exposed stratigraphic sequence of the Burns formation starts with deposition of dry aeolian sediment derived from a former watershed. Then, due to the rise of the water table, wet sediments of a sabkha rest atop the dry aeolian cycle to comprise a retrogradational sequence. At Terby and Gale craters, an opposite stratigraphic sequence starts with the wet deposition of the sabkha fill. Then, due to the fall of the water table, the dry aeolian sedimentation progrades atop to the sabkha fill to comprise a progradational sequence. We conclude that the various stratigraphic sequences at the MCSH system, described here, represent different possible analog scenarios for diverse depositional sequences on Mars, in all cases involving groundwater activity.

  18. Évolution de la qualité cellulaire du lait de vache : Description et facteurs de variation chez deux grands troupeaux soumis à la traite tri-quotidienne (Sahel Tunisien

    Directory of Open Access Journals (Sweden)

    Youssef M'SADAK

    2016-07-01

    Full Text Available The present work, relating to a description of the Individual Cellular Counting (ICC of the milk followed by an analysis of factors of cellular evolution, was carried out in two large cattle farms in a semi-arid environment (Sousse region, Tunisia. The first farm belongs to the private sector (Gloulou-Sidi Bou Ali and the second one to the state sector (OTD-Enfidha, all subjected to indoors tri-daily mechanical milking. We have concluded that 25% of cows have an arithmetic average (AA of > 200 000 cells/ml for ICC. The AA of cows ICC was 371 000 cells /ml, while the geometric average (GA of cows ICC was only 107 500 cells /ml. The median was 73 000 cells /ml, value which is close to the GA and widely away from the AA, thus showing the utility of the GA. In both considered farms, the change in ICC was inversely proportional to milk production. However, ICC showed an increase with the rank of lactation, lactation stage and the spring calving season.

  19. Amélioration des ovins dans l'Ouémé et le Plateau en République du Bénin. Enjeux de croisement des ovins Djallonké avec les moutons du Sahel

    Directory of Open Access Journals (Sweden)

    Salifou, S.

    2002-01-01

    Full Text Available Sheep Management in Oueme and Plateau Departments of Republic of Benin. Stakes of Djallonke Crossbreeding with Sahelian Sheep. The present study is a reflection through bibliographical review and on the current situation of sheep breeding in Oueme and Plateau of Benin. This study situates the crossbreeding of Djallonke with Sahelian sheep and prospects some strategies that could be adopted in the context of sheep breeding in Oueme and Plateau of Benin.

  20. La regeneration de l'espace sylvo-pastoral au Sahel : une etude de l'effet de mesures de conservation des eaux et des sols au Burkina Faso

    NARCIS (Netherlands)

    Hien, F.G.

    1995-01-01

    Sahelian rangelands are subject to degradation caused by physical and human factors. This report presents the results of recent research in Burkina Faso on methods for regenerating such rangelands. It begins with an overview of existing regeneration methods. Quantitative ecological field work

  1. What Drives Human Migration in Sahelian Countries? A Meta-analysis

    NARCIS (Netherlands)

    Neumann, K.; Hermans, Frans

    2017-01-01

    The Sahel region has one of the most mobile populations in the world, with migration serving as a common household strategy to increase livelihood and social resilience. However, the Sahel region's population is extremely heterogeneous, and the processes and factors that contribute to migration are

  2. 237-IJBCS-Article-Dr Traore

    African Journals Online (AJOL)

    Dr Gatsing

    Sahel. However, the long term effects of substrates are to be assessed. ... Keywords: Water, Sahel, aquatic invading plants, raw and composted substrate, yield benefit. INTRODUCTION. Cotton is .... MF*: Mineral Fertilization corresponds to 0.133 g/pot of complex fertilizer NPKSB and 0.133 g/pot of urea with maize and 0.13 ...

  3. West Africa

    International Development Research Centre (IDRC) Digital Library (Canada)

    freelance

    Climate Change (IPCC) reckons that, in general, continued global warming will lead to higher temperatures, increased dryness in the Sahel, increased variability in precipitations and storms of heightened intensity. In catchment areas, particularly in the. Sahel, we will see a reduction in the vegetational cover, infiltration and ...

  4. Natural Resources Management for Sustainable Food Security in ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Natural Resources Management for Sustainable Food Security in the Sahel. The agricultural and pastoral production deficit combined with the general rise in food prices has increased food insecurity in the Sahel. In order to guarantee their food security, rural populations adopt agricultural techniques aimed at maximizing ...

  5. Integrated Nutrient and Water Management for Sustainable Food ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF). In the Sahel, agricultural production is strictly limited by drought and low soil fertility. In 2005 and 2010, these two factors led to food scarcity in Niger. However, innovative technologies such as microdose fertilization ...

  6. Maxillofacial and mandibular phenotypes in the skulls of red Sokoto ...

    African Journals Online (AJOL)

    This work examined phenotypic expressions in the anatomy of the mandible and maxillofacial region of the Red Sokoto and Sahel goats in Nigeria. The infraorbital foramen was placed above premolar two (PM2) in Red Sokoto but above premolar one (PM1) in Sahel. The Red Sokoto displayed interdigital septa (ruggae) ...

  7. All projects related to | Page 290 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-03-01

    Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF). Project. In the Sahel, agricultural production is strictly limited by drought and low soil fertility. Start Date: March 1, 2011. End Date: September 1, 2014. Topic: FOOD CROPS, SOIL FERTILITY, FERTILIZERS, FERTILIZING, ...

  8. All projects related to Burkina Faso | Page 3 | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2017-07-26

    Natural Resources Management for Sustainable Food Security in the Sahel. Project. The agricultural and pastoral production deficit combined with the general rise in food prices has increased food insecurity in the Sahel. End Date: July 26, 2017. Topic: DESERTIFICATION, Natural Resources, ADAPTATION TO CHANGE, ...

  9. All projects related to | Page 362 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Region: Burkina Faso, Mali. Program: Agriculture and Food Security. Total Funding: CA$ 1,142,600.00. Natural Resources Management for Sustainable Food Security in the Sahel. Project. The agricultural and pastoral production deficit combined with the general rise in food prices has increased food insecurity in the Sahel.

  10. Changes in densities of Sahelian bird species in response to recent ...

    African Journals Online (AJOL)

    Habitat loss in the Sahel region of West Africa has been pronounced, due to anthropogenic effects and (potentially) climate change. Although strong links have been found between conditions in the Sahel and subsequent breeding populations of certain Palaearctic migrants, the effects of these fluctuations upon Afrotropical ...

  11. Integrated Nutrient and Water Management for Sustainable Food ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF). In the Sahel, agricultural production is strictly limited by drought and low soil fertility. In 2005 and 2010, these two factors led to food scarcity in Niger. However, innovative technologies such as ... Date de début. 1 mars 2011 ...

  12. Resource limitations in Sahelian agriculture

    NARCIS (Netherlands)

    Breman, H.; Groot, J.J.R.; Keulen, van H.

    2001-01-01

    In general, Africa has poor soils and unfavorable climates for agriculture. This is specially so in the Sahel of West Africa. Moreover, poor infrastructure means that fertilizer prices are higher in the Sahel than in Europe. Sahelian farmers have few incentives to maintain, let alone improve output.

  13. Page 1 Fuelwood and stoves 91 References Ascough J 1981 ...

    Indian Academy of Sciences (India)

    OECD 1978 Energy in the development of the Sahel Club du Sahel, Report, OECD, Paris, France. Prasad C R, Prasad K K & Reddy A K N 1974 Econ. Pol. Weekly 9 1347. Prasad K K 1980 Some performance tests on open fires and the family cooker, Report, Dept. of. Appl. Physics, Technical University of Eindhoven, The ...

  14. Publications | Page 176 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Design and implementation of runoff harvesting basins for supplemental irrigation in the Burkinabe Sahel (restricted access). Climate change in the Sahel will mean frequent droughts and larger dry spells, where farmers who benefit from dams and irrigated areas is less than 2%. The present study proposes a methodology ...

  15. GLOBAL JOURNAL OF AGRICULTURAL SCIENCES ISSN 1596-2903

    African Journals Online (AJOL)

    Ada Global

    African Sahel, the study created scenarios of future climatic changes based on arbitrary data and analogues of historical climatic data. The results indicated that a possible climatic change which involves up to 50% reduction in the mean rainfall for locations in the West African Sahel will reduce yields substantially and in ...

  16. Publications | Page 592 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 5911 - 5920 of 6356 ... Farming and livestock production in the Sahel : merging the two solutions (open access). The women of Toukounous, a small town 20 km from Niamey, are participating in a new departure from the agricultural history of Niger and the Sahel. Only now is integrated farming and livestock production ...

  17. Publications | Page 614 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 6131 - 6140 of 6378 ... Farming and livestock production in the Sahel : merging the two solutions (open access). The women of Toukounous, a small town 20 km from Niamey, are participating in a new departure from the agricultural history of Niger and the Sahel. Only now is integrated farming and livestock production ...

  18. Publications | Page 602 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 6011 - 6020 of 6388 ... Farming and livestock production in the Sahel : merging the two solutions (open access). The women of Toukounous, a small town 20 km from Niamey, are participating in a new departure from the agricultural history of Niger and the Sahel. Only now is integrated farming and livestock production ...

  19. Publications | Page 625 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 6241 - 6250 of 6379 ... Farming and livestock production in the Sahel : merging the two solutions (open access). The women of Toukounous, a small town 20 km from Niamey, are participating in a new departure from the agricultural history of Niger and the Sahel. Only now is integrated farming and livestock production ...

  20. Publications | Page 593 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 5921 - 5930 of 6356 ... Farming and livestock production in the Sahel : merging the two solutions (open access). The women of Toukounous, a small town 20 km from Niamey, are participating in a new departure from the agricultural history of Niger and the Sahel. Only now is integrated farming and livestock production ...

  1. Can Old Regimes Handle New Wars?

    DEFF Research Database (Denmark)

    Henningsen, Troels

    Research on New Wars argues that since the 1980s states and regimes have become more vulnerable to violence from non-state actors. Two developments in the Sahel region support the New Wars thesis: an increase in Islamist radicalization and new access to the global black market, both of which......, the paper finds that regimes in the Sahel region are still able to cope with the rise in non-state threats. The paper first shortly compares the longevity of the present regimes in the Sahel region to all previous ones, second examines in-depth how Chad and Mali fight the insurgents. Findings are that since...

  2. perceptions paysannes sur la double riziculture et les variétés de riz ...

    African Journals Online (AJOL)

    Irrigation et intensification de la production agricole au Sahel : perceptions paysannes sur la double riziculture et les variétés de riz utilisées sur les aménagements hydro - agricoles au Niger.

  3. Evaluation of the effects of intravenous anaesthesia using a ...

    African Journals Online (AJOL)

    medetomidine for total intravenous anaesthesia were evaluated in six sahel goats. The goats were administered a combination of ketamine (5mg/kg) and medetomidine (0.01mg/kg) intravenously. Baseline measurements of heart rate, respiratory ...

  4. An appraisal of the of eco-climatic characteristics in Northern Nigeria

    African Journals Online (AJOL)

    USER

    2013-08-01

    Aug 1, 2013 ... to adversely modify the natural resource and the environment as a whole. .... savanna vegetation types; Guinea, Sudan and Sahel savanna, the density of trees ..... Natural Hazard (NHAZ) (Online Jan. 2013 on SpringerLink:).

  5. A Difficult Time: Migrant work and the WoDaaBe in Niger

    National Research Council Canada - National Science Library

    Loftsdottir, Kristin

    2001-01-01

    ... before; words that reflect WoDaaBe nomads' concern for their present situation. Repeated droughts in the Sahel area of Niger have led to losses of livestock and reduced the possibility of maintaining a nomadic way of life...

  6. Partenariat pour l'adaptation des populations vulnérables à la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    . Climate change poses a real challenge to communities of the Sahel, that of surviving in a fragile environment undergoing rapid mutation. View moreInfoClim : Platform for Helping Vulnerable Communities Adapt to Climate Change ...

  7. Effects of dexamethasone on leukocytic responses in pregnant ...

    African Journals Online (AJOL)

    WBC) and differential leukocyte counts (DLC) (neutrophils, eosinophils, lymphocytes, monocytes and basophils). Dexamethasone significantly (P<0.05) increased total WBC and neutrophil counts in both pregnant Yankasa ewes and Sahel does, ...

  8. Violent Conflicts and Civil Strife in West Africa: Causes, Challenges and Prospects

    National Research Council Canada - National Science Library

    Annan, Nancy

    2014-01-01

    .... While violent conflicts are declining in the sub-region, recent insurgencies in the Sahel region affecting the West African countries of Mali, Niger and Mauritania and low intensity conflicts surging...

  9. Interspecific and intraspecific differences in habitat use and their conservation implications for Palaearctic harriers on Sahelian wintering grounds

    NARCIS (Netherlands)

    Buij, Ralph; Van der Goes, Dirk; De Iongh, Hans H.; Gagare, Sama; Haccou, Patsy; Komdeur, Jan; De Snoo, Geert; Sergio, Fabrizio

    The floodplains of the West-African Sahel region have experienced extensive habitat transformation during the past four decades, coinciding with an impoverishment of raptor populations. We investigated foraging patterns of Palaearctic migratory Eurasian Marsh Harriers Circus aeruginosus, Pallid

  10. Prehistoric dark soils/sediments of Central Sudan; case study from the Mesolithic landscape at the Sixth Nile Cataract

    Czech Academy of Sciences Publication Activity Database

    Lisá, Lenka; Bajer, A.; Pacina, J.; McCool, J-P.; Cílek, Václav; Rohovec, Jan; Matoušková, Šárka; Kallistová, Anna; Gottvald, Z.

    2017-01-01

    Roč. 149, č. 1 (2017), s. 273-282 ISSN 0341-8162 Institutional support: RVO:67985831 Keywords : climate change * micromorphology * sahel * saprolite * soil chemistry Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.191, year: 2016

  11. Natural Resources Management for Sustainable Food Security in ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Natural Resources Management for Sustainable Food Security in the Sahel. The agricultural and ... agricoles au Sahel. Au cours des vingt dernières années, plusieurs innovations visant à améliorer les rendements des cultures vivrières ont été développées dans les centres de recherche agronomique d'Afrique de l.

  12. Gestion intégrée de l'eau et des nutriments pour la production ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Gestion intégrée de l'eau et des nutriments pour la production durable des cultures vivrières (FCRSAI). Au Sahel, la sécheresse et la piètre fertilité des sols limitent ... Outputs. Reports. Integrated nutrient and water management for sustainable food production in the Sahel : final technical report (March 2011 - August 2014) ...

  13. Gestion des ressources naturelles pour une sécurité alimentaire ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Gestion des ressources naturelles pour une sécurité alimentaire durable au Sahel. Au Sahel, le déficit de la production agricole et pastorale, combiné à la hausse générale des prix des denrées, ont augmenté l'insécurité alimentaire. Pour garantir leur sécurité alimentaire, les populations rurales utilisent des techniques de ...

  14. Conceptualizing the mobility of space through the Malian conflict

    DEFF Research Database (Denmark)

    Walther, Olivier; Retaillé, Denis

    2013-01-01

    The ongoing Malian conflict has sparked renewed media and academic interest in the Sahel. This paper shows how the various actors involved in the conflict, including nation-states, Tuareg rebels, and Islamist terrorists have adopted mobile strategies, which are not effectively explained using tra...... argue, is better suited to grasping the complexity of contemporary conflicts in the Sahel-Sahara than the traditional approach based on territories....

  15. Dégâts des bruches sur le pouvoir germinatif des graines de quatre ...

    African Journals Online (AJOL)

    SARAH

    29 févr. 2016 ... développement des moisissures et autres parasites. L'effet additif des différents dégâts peut occasionner des pertes économiques de 100%, car avec des .... Bruchidae ravageurs des légumineuses alimentaires au Sahel séminaire sur la lutte intégrée au Sahel du 03 au 09 Avril : 393. Dakar. (Sénégal).

  16. Weakening and Shifting of the Saharan Heat Low Circulation During Wet Years of the West African Monsoon

    CERN Document Server

    Shekhar, Ravi

    2016-01-01

    The correlation between increased West African monsoon rainfall and anomalously low surface pressure over the Sahara is well established in observations and global climate models, and has been interpreted as a strengthening of the Saharan Heat Low (SHL) during wet monsoon years. This study uses two atmospheric reanalysis datasets to examine interannual variability of Sahel rainfall and the shallow Saharan Heat Low circulation, which consists of the near surface SHL and the Saharan High in the lower mid-troposphere. During wet Sahel years, the SHL circulation shifts poleward, producing a drop in low-level geopotential height and surface pressure over the Sahara. Statistically removing the effect of the poleward shift from the low-level geopotential eliminates significant correlations between this geopotential and Sahel precipitation. As the SHL circulation shifts poleward, its mid-tropospheric divergent outflow decreases, indicating a weakening of its overturning mass flux. The poleward shift and weakening of ...

  17. Studies of 21st-Century Precipitation Trends Over West Africa

    Science.gov (United States)

    Druyan, Leonard M.

    2010-01-01

    West Africa includes a semi-arid zone between the Sahara Desert and the humid Gulf of Guinea coast, approximately between 10 N and 20 N, which is irrigated by summer monsoon rains. This article refers to the region as the Sahel. Rain-fed agriculture is the primary sustenance for Sahel populations, and severe droughts (in the 1970s and 1980s), therefore, have devastating negative societal impacts. The future frequency of Sahel droughts and the evolution of its hydrological balance are therefore of great interest. The article reviews 10 recent research studies that attempt to discover how climate changes will affect the hydrology of the Sahel throughout the 21st century. All 10 studies rely on atmosphere ocean global climate model (AOGCM) simulations based on a range of greenhouse gas emissions scenarios. Many of the simulations are contained in the Intergovernmental Panel on Climate Change archives for Assessment Reports #3 and #4. Two of the studies use AOGCM data to drive regional climate models. Seven studies make projections for the first half of the 21st century and eight studies make projections for the second half. Some studies make projections of wetter conditions and some predict more frequent droughts, and each describes the atmospheric processes associated with its prediction. Only one study projects more frequent droughts before 2050, and that is only for continent-wide degradation in vegetation cover. The challenge to correctly simulate Sahel rainfall decadal trends is particularly daunting because multiple physical mechanisms compete to drive the trend upwards or downwards. A variety of model deficiencies, regarding the simulation of one or more of these physical processes, taints models climate change projections. Consequently, no consensus emerges regarding the impact of anticipated greenhouse gas forcing on the hydrology of the Sahel in the second half of the 21st century.

  18. Activation of Sahelian monsoon under future warming

    Science.gov (United States)

    Schewe, Jacob; Levermann, Anders

    2015-04-01

    Rainfall variability in the Sahel has been affecting the lives of millions through devastating droughts, such as in the 1970s and 80s, but also destructive rain and flood events. Future climate change is likely to alter rainfall patterns, but model projections for the central Sahel diverge significantly, with climate models simulating anything between a slight drying and a substantial wetting trend. Here we analyze 30 coupled global climate model simulations from the CMIP5 archive. We identify seven models where central Sahel rainfall increases by 40% to 300% over the 21st century, under the RCP8.5 concentration pathway. The same models also outperform the rest of the ensemble in reproducing the magnitude of the 1970s/80s drought. The magnitude and seasonality of the projected future rainfall change, together with a concurrent increase in near-surface wind speed, indicate a northward expansion of the West African monsoon domain. We further find that Sahel rainfall does not increase linearly with rising global temperatures; it is insensitive to moderate warming but then abruptly intensifies beyond a certain temperature. This non-linearity is even more pronounced when instead of global warming, sea surface temperature change in the tropical Atlantic moisture source region is considered. We propose an explanation for this behavior based on a self-amplifying dynamic-thermodynamical feedback, and suggest that the gradual increase in oceanic moisture availability under climate change can trigger the sudden activation of a continental monsoon in the Sahel region, which reaches further inland than the present-day, predominantly coastal West African monsoon. Such an abrupt regime change in response to gradual forcing would be consistent with paleoclimatic records from the Sahel region. More detailed comparison between the model simulations that exhibit this sudden rainfall increase under future warming and those that do not may help to verify this hypothesis.

  19. Securing Land Tenure, Improving Food Security and Reducing ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Securing Land Tenure, Improving Food Security and Reducing Poverty in Rural West Africa. In November 2003, the heads of states belonging to the Permanent Interstate Committee on Drought Control in the Sahel (CILSS) and to the Economic Community of West African States (ECOWAS) undertook to work toward the ...

  20. Improving operational land surface model canopy evapotranspiration in Africa using a direct remote sensing approach

    CSIR Research Space (South Africa)

    Marshall, M

    2013-03-01

    Full Text Available Climate change is expected to have the greatest impact on the world's economically poor. In the Sahel, a climatically sensitive region where rain-fed agriculture is the primary livelihood, expected decreases in water supply will increase food...

  1. A Review Of Preterm Admissions Into Special Care Baby Unit, In ...

    African Journals Online (AJOL)

    There is little or no report of preterm (babies born less than 37 completed weeks of gestation) admission from this part of Sahel Savannah of Nigeria. This study of four-year period is presented to identify areas that require improvement, such as in the Labour ward and neonatal care. The case files of the 428 preterm ...

  2. HABITATS AND UTILIZATIONS OF Lippia multiflora MOLDENKE ...

    African Journals Online (AJOL)

    Journal Molecules, 15 : 7825 - 7839. Bornet P., Arbonier M. and P. Grard. 2008. Ligneux du sahel. agris.fao.org. Chadare F. J., Hounhouigan J. D., Linnemann A. R., Nout M. J. R. and M. A. J. S. Van Boekel. 2008. Indigenous knowledge and processing of Adansonia digitata L. food products in Benin. Ecology of food and nu-.

  3. Communal conflict, civil war, and the state: Complexities ...

    African Journals Online (AJOL)

    presidential election, pastoralist conflicts in the Sahel region, and the many conflicts between different ethnic .... systems that characterise most countries where communal conflicts are common. Such systems include a .... and the Americas saw four active conflict years each, and the Middle East only one. Looking at unique ...

  4. tunisia

    African Journals Online (AJOL)

    lanez

    31 déc. 2014 ... ABSTRACT. The aim of this study is to evaluate mainly the conditions the milking and the mammary health status of cows in the central East Sousse (Tunisian Sahel). The study was conducted on a sample of 20 small and means dairy cattle herds aboveground divided into two study areas. This study.

  5. Assessment of the Teleconnection Between El Nino Southern ...

    African Journals Online (AJOL)

    NIMET) from six (6) synoptic stations selected across three (3) geographical regions in Nigeria for a period of 26 years (1988 - 2013). Cluster analysis grouped the rainfall data into three clusters namely Coastal South, Middle belt and Sahel North, ...

  6. Fluxes and distribution of dissolved iron in the eastern (sub-) tropical North Atlantic Ocean

    NARCIS (Netherlands)

    Rijkenberg, M.J.A.; Steigenberger, S.; Powell, C.F.; van Haren, H.; Patey, M.D.; Baker, A.R.; Achterberg, E.P.

    2012-01-01

    Aeolian dust transport from the Saharan/Sahel desert regions is considered the dominant external input of iron (Fe) to the surface waters of the eastern (sub-) tropical North Atlantic Ocean. To test this hypothesis, we investigated the sources of dissolved Fe (DFe) and quantified DFe fluxes to the

  7. Quantitative analyses of shrinkage characteristics of neem ...

    African Journals Online (AJOL)

    Quantitative analyses of shrinkage characteristics of neem (Azadirachta indica A. Juss.) wood were carried out. Forty five wood specimens were prepared from the three ecological zones of north eastern Nigeria, viz: sahel savanna, sudan savanna and guinea savanna for the research. The results indicated that the wood ...

  8. Valorizing Research Results and Innovations in Burkina Faso ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    In Burkina Faso, scientific research, invention and innovation have generated many results that could contribute to endogenous development. However, these results are little known, ... Gestion intégrée de l'eau et des nutriments pour la production durable des cultures vivrières (FCRSAI). Au Sahel, la sécheresse et la piètre ...

  9. Spatial variability and farmer resource allocation in millet production in Niger

    NARCIS (Netherlands)

    Gandah, M.

    1999-01-01

    The Sahel of West Africa is the agro-ecological zone located between 12 oand 16 oN, with an annual rainfall of between 300 and 1000 mm. Crops are grown in a subsistence type of agriculture during the 75 to 125 days growing period between May and

  10. Download this PDF file

    African Journals Online (AJOL)

    En-Joy

    Aire, 1986; Waziri et al, 2002). Information on changes in foetal fluids and in foetal disposition during known stages of pregnancy in Sahel goats is currently not available. The purpose of the study was therefore, to determine the development of foetal fluid and foetal disposition (location and orientation) at various stages of ...

  11. African Climate Change Fellowship | CRDI - Centre de recherches ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Spatial fields' dispersion as a farmer strategy to reduce agro-climatic risk at the household level in pearl millet-based systems in the Sahel : a modeling perspective. Articles de revue. Indigenous knowledge in seasonal rainfall prediction in Tanzania : a case of the South-western Highland of Tanzania. Articles de revue.

  12. The Status of Solar Energy as Fuel.

    Science.gov (United States)

    Hall, D. O.

    1979-01-01

    Discused is the biological conversion of solar energy via photosynthesis into stored energy in the form of biomass. Detailed are the research and development programs on biomass of the United States, Canada, Australia, New Zealand, Europe, Brazil, Philippines, Sahel, India, and China. (BT)

  13. Woody plants in agro-ecosystems of semi-arid regions

    NARCIS (Netherlands)

    Breman, H.; Kessler, J.J.

    1995-01-01

    A quantitative analysis of the role of woody plants in semi-arid regions, focusing on the Sahel and Sudan zones in West-Africa, is given for the assessment of their benefits in agro-sylvopastoral land-use systems with productive and sustainability objectives.

  14. Registering the Human Terrain: A Valuation of Cadastre

    Science.gov (United States)

    2008-01-01

    Lebanon and Yemen , wide swaths of South America (Amazonia) and Africa, the Sahel and the Horn, parts of the southern Philippines, several Indonesian...details of it— geology , drainage, crops, soils, economic use, affi liation of the owner, and 42 | other variables. Th is openly available, but oft en

  15. (FGA) sponges and Equine Chorionic Gonadotrophin (ECG)

    African Journals Online (AJOL)

    The objective of the present study was to evaluate the effect of a progestagen treatment alone or in combination with equine chorionic gonadotrophin (eCG) on estrus response in Sahel (SH) goats. One hundred (n=100) SH does were treated with 30 mg fluorogestone acetate (FGA) sponge for 14 days. At the end ...

  16. Morocco: A New Financial Capital?

    National Research Council Canada - National Science Library

    Davis, Kurt

    2013-01-01

    ...-speaking African markets. Morocco does not pretend to hide its ambitions to head the Community of Sahel-Saharan States (CEN-SAD). Morocco is unreasonably not a member of the African Union--something that clearly will have to change.

  17. Senegalese NGO renews commitment to research excellence ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-28

    Apr 28, 2016 ... In 2005, it took over, and continues to build on, the Sahel program created in 1993 by the International Institute for Environment and Development. Through its participation in IDRC's Resource Mobilization for Research (RMR) project, IED Afrique reviewed and renewed its strategic direction in 2012-13.

  18. Abdim\\'s Stork Ciconia abdimii in Niger: population size, breeding ...

    African Journals Online (AJOL)

    Abdim's Stork is a common breeding bird in most human settlements across the Sahel. However, very few studies have surveyed the population and described its breeding and feeding ecology during the breeding season. We identified the breeding range in Niger, surveyed nests in 23 villages/towns and, based on the ...

  19. A system to measure surface fluxes of momentum, sensible heat, water vapour and carbon dioxide

    NARCIS (Netherlands)

    Moncrieff, J.B.; Massheder, J.M.; Bruin, de H.; Elbers, J.A.; Friborg, T.; Heusinkveld, B.; Kabat, P.; Scott, S.; Soegaard, H.; Verhoef, A.

    1997-01-01

    An eddy covariance system is described which has been developed jointly at a number of European laboratories and which was used widely in HAPEX-Sahel. The system uses commercially available instrumentation: a three-axis sonic anemometer and an IR gas analyser which is used in a closed-path mode,

  20. Assessment of biofuel potential of dead neem leaves (Azadirachta ...

    African Journals Online (AJOL)

    TIZE

    2016-08-24

    Aug 24, 2016 ... the forest in the Sahel region. Therefore, the surface area which could be preserved through the year and in 10 years is illustrated in Table 3. From Table 3, the valorisation of the biogas as cooking energy from dead neem biomass quantified in Maroua town could allow the preservation of 567.45 ha/year of.

  1. (3.0. Akpede, FWACP, FMCP, Department of Paediatrics, EA ...

    African Journals Online (AJOL)

    2001-11-01

    Nov 1, 2001 ... NUTRITIONAL RICKETS IN YOUNG NIGERIAN CHILDREN IN THE SAHEL SAVANNA*. (3.0. Akpede, FWACP ... children of Moslem families (p <0.05) and children whose mothers were full-time housewives, unskilled or traders ... fever and difficult/rapid breathing), history of bowing of the legs in the child's ...

  2. 37(4) All.cdr

    African Journals Online (AJOL)

    HP

    Biometry of the Ovary in Balami, Yankassa Sheep and Sahel Goat. Aliyu, A.; Peter, I. D.; Zakariah M: ... stands at 1078.2 million and 861.9 million their economic importance is quite respectively (Aziz, 2010). ... and 53.8million (6.2%) goats (Aziz, 2010). these qualities, careful selection and breeding. These species of animals ...

  3. Effects of various protein sources on performance and cost-benefit ...

    African Journals Online (AJOL)

    Effects of various protein sources on performance and cost-benefit analysis of broilers finisher chickens. ... Sahel Journal of Veterinary Sciences ... A total of 120 Marshal strain of broiler chickens, aged four weeks were used to investigate the efficacy of different protein sources in enhancing productive and carcass indices of ...

  4. jfewr ©2017 - jfewr Publications

    African Journals Online (AJOL)

    LAMINE M. Ousmane

    ABSTRACT. The aim of this study was to investigate the possibilities of the propagation of Leptadenia hastata cuttings during the 3 seasons of the year in Sahel. The cuttings of 20 cm of length, collected from the basal, apical and root parts of the plants, were used. Study investigations consisted in observing the buds and ...

  5. All projects related to | Page 406 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Topic: WOMEN'S RIGHTS, WATER RESOURCES, WATER MANAGEMENT, GENDER ANALYSIS. Region: North of Sahara, South of Sahara. Program: Employment and Growth. Total Funding: CA$ 480,300.00. Women's Right to Water for Agricultural Use in the Sahel (Mauritanie, Niger, Sénégal). Project. Rural women in ...

  6. InfoClim : Platform for Helping Vulnerable Communities Adapt to ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Climate change poses a real challenge to communities of the Sahel, that of surviving in a fragile environment undergoing rapid mutation. To meet this challenge, local and national actors must be aware of the phenomenon, monitor changes on the ground, and have access to strategies for adaptation and preparedness.

  7. Search | Page 17 | IDRC - International Development Research Centre

    International Development Research Centre (IDRC) Digital Library (Canada)

    Animal vaccines key to poor farm families' health and prosperity in ... Animal vaccines key to poor farm families' health and prosperity in Africa ... five common animal diseases in Africa, and does not require refrigeration. ... Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel .

  8. Le microdosage des engrais, une innovation qui profite aux femmes ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le microdosage des engrais, une innovation qui profite aux femmes du Sahel. 06 juin 2016. Ibro M Abdoulaye, Baco Mohamed Nasser, Badiori Ouatara, Sogodogo Diakalia, Mahaman Sabiou,Akponikpè PB Irenikatche, Derek Peak, Kimaro Anthony et Koala Saidou. Grâce à l'application localisée de petites quantités ...

  9. Author Details

    African Journals Online (AJOL)

    ... dans deux zones a ecosystemes contrastes au Sahel Abstract PDF · Vol 29, No 2 (2017): Special Issue - Articles Influence du systeme de riziculture intensif (SRI) sur les attaques des principaux insectes depredateurs dans les perimetres rizicoles irrigues de Karfiguela et de la vallee du Kou au Burkina Faso Abstract PDF.

  10. NJP VOLUME 41 NO 4

    African Journals Online (AJOL)

    PROF. EZECHUKWU

    2014-04-09

    , Nigeria. Sahel Med. J 2008;11(4):114-117. 25. Adeleke SI. Congenital adrenal hyperplasia due to 11-beta hy- droxylase deficiency in a female adolescent. World J Innov Med. 2009;1(1):1-5. 26. Sowande OA, Adejuyigbe O.

  11. Effect of polyethylene glycol (PEG) 6000 on germination and ...

    African Journals Online (AJOL)

    Millet crop is an important cereal for food security and the fight against poverty and malnutrition in the arid Sahel. It is a staple grain for millions of people in West Africa and India. It has the advantage of tolerating drought-prone environments and low fertility soils. Recent climate change exacerbates the phenomenon of ...

  12. 12 Boyd 03

    African Journals Online (AJOL)

    Administrator

    Under his direction SOS Sahel-Niger was instrumental in the construction of medical clinics in isolated villages. Mariko probably had the most extensive personal library in Niger. There were bookcases and shelves of books in every room of his home and a vast library at his museum on the left bank of the river. Scholars.

  13. Developing technology options for rice integrated crop management ...

    African Journals Online (AJOL)

    Mo

    Developing technology options for rice integrated crop management in the. Sahel Zone of West Africa: Case of irrigated rice production the Senegal River. Valley. M. Kebbeh, K. Miezan and M. Camara1. Production Economist, Breeder and Visiting Scientist in Agronomy at The Africa Rice Center (WARDA). Address: BP 96 ...

  14. Perspective: Animal-vegetation relations which optimise production ...

    African Journals Online (AJOL)

    The broad objective is to improve the standard of living of farmers/herders through identification of complementary vegetation-use under mixed animal species grazing. This paper aims to (1) review mixed-grazing research and development carried out in Ireland and in the semi-arid Senegalese Sahel; (2) evaluate results in ...

  15. Quantified Effects of Late Pregnancy and Lactation on the Osmotic ...

    African Journals Online (AJOL)

    Alteration in erythrocyte osmotic fragility (EOF) during late pregnancy and lactation was investigated in 46 apparently healthy adult Sahel goats weighing 18- 30 kg consisting of 16 non-pregnant dry (NPD), 15 pregnant (PRE) and 15 lactating (LAC) animals. The PRE and LAC were in third trimester and nursing periods, ...

  16. Author Details

    African Journals Online (AJOL)

    Adimula, IA. Vol 17, No 1 (2005) - Articles Effects of rain on microwave and satellite communications in equatorial and tropical regions. Abstract · Vol 20, No 2 (2008) - Articles Temperature and precipitation relation in the Sub-Sahel Abstract · Vol 20, No 2 (2008) - Articles Analysis of radiosonde data on tropospheric water ...

  17. Author Details

    African Journals Online (AJOL)

    Mossi Maïga, I. Vol 107 (2016) - Articles Irrigation et intensification de la production agricole au Sahel : perceptions paysannes sur la double riziculture et les variétés de riz utilisées sur les aménagements hydro - agricoles au Niger Abstract PDF. ISSN: 1997-5902. AJOL African Journals Online. HOW TO USE AJOL.

  18. Browse Title Index

    African Journals Online (AJOL)

    Items 251 - 256 of 256 ... A Garba, BM Bolajoko, IJ Barde, A Ahmed, I Sa'adatu, I Agang, AS Abdullahi, HA Bakan, UA Turaki, A Abdurrahman, JN Goji. Vol 10, No 2 (2012), Time-related and sequential developmental horizons of Sahel goat foetuses, Abstract PDF. MA Waziri, NM Sivachelvan, AR Mustapha, AY Ribadu.

  19. SJVS October 2012 correction

    African Journals Online (AJOL)

    HP USER

    Abstract. The aim of the present study was to follow the time related developmental changes of caprine foetuses to aid in their age determination. Certain gross external features along with body size changes were studied. Twenty five pregnant Sahel does of known gestational age managed under controlled conditions were ...

  20. Establishment of regional radiotherapy centres: a strategy for ...

    African Journals Online (AJOL)

    Establishment of regional radiotherapy centres: a strategy for improving access to cancer treatment in Nigeria. J U Onakewhor, L R Airede, K I Airede. Abstract. No Abstract. Sahel Medical Journal Vol. 10 (2) 2007: pp. 38-42. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL ...

  1. Browse Title Index

    African Journals Online (AJOL)

    Items 51 - 100 of 256 ... M Sanusi, A Rabi, UD Doma, J Haruna. Vol 15, No 1 (2017), Comparative effects of dexamethasone on placental and foetal organ weights and some linear body measurements in Yankasa sheep and Sahel goats, Abstract PDF. D Yahi, N.A. Ojo, G.D. Mshelia, V.A. Maina. Vol 15 (2017): Special Issue ...

  2. Farmers' perceptions of erosion by wind and water in northern Burkina Faso

    NARCIS (Netherlands)

    Visser, S.M.; Leenders, J.K.; Leeuwis, M.

    2003-01-01

    Wind and water erosion are widespread phenomena throughout the Sahel, especially in the early rainy season, when high-intensity rainstorms are often preceded by severe windstorms. This paper describes the results of a survey on the farmers' perceptions of wind and water erosion processes and control

  3. Meer dan zandkastelen : Architektonisch reisverhaal

    NARCIS (Netherlands)

    Van der Eerden, J.

    1993-01-01

    This book is the account of a journey through the Sahara, from the Maghreb to the countries of the Sahel. The writer describes the history of the area and the technology, styles and backgrounds of its architecture. This is alternated with an account of the writer's experiences during the trip

  4. Author Details

    African Journals Online (AJOL)

    Addy, E. O.. Vol 78, No 11 (2001): - Articles Nutritional rickets in young Nigerian children in the Sahel Savanna Abstract PDF. ISSN: 0012-835X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

  5. East African Medical Journal - Vol 78, No 11 (2001)

    African Journals Online (AJOL)

    Nutritional rickets in young Nigerian children in the Sahel Savanna · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. G. O. Akpede, E. A. Solomon, I. Jalo, E. O. Addy, A. I. Banwo, B. A. Omotara, 568-575. http://dx.doi.org/10.4314/eamj.v78i11.8945 ...

  6. Browse Title Index

    African Journals Online (AJOL)

    Vol 78, No 11 (2001):, Nutritional rickets in young Nigerian children in the Sahel Savanna, Abstract PDF. G. O. Akpede, E. A. Solomon, I. Jalo, E. O. Addy, A. I. Banwo, B. A. Omotara. Vol 93, No 2 (2016), Nutritional status and associated factors among school going children aged 4-10 years in Kisii Central Sub- County ...

  7. Animal Research International - Vol 6, No 1 (2009)

    African Journals Online (AJOL)

    Survey Of Ketosis And Hypoproteinaemia In Slaughtered Cattle In The Sahel Region Of Nigeria · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. IC Igbokwe, SN Okonkwo, HG Hamza, NA Igbokwe. http://dx.doi.org/10.4314/ari.v6i1.48099 ...

  8. Influence of shift work on the physical work capacity of Tunisian nurses

    African Journals Online (AJOL)

    Methods: It is a cross-sectional design using a standardized questionnaire and many physical capacity tests on a representative sample of 1181 nurses and nursing assistants from two university hospital centers of the school of Medicine of Monastir located in the Tunisian Sahel. 293 participants have been recruited by ...

  9. Irrigation and climate information in Burkina Faso (AARC) | Page 2 ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Since the 1970s, the Sahel has experienced a marked decline in rainfall and a high variability in the timing of the rainy season (Intergovernmental Panel on Climate Change, 2007). As a result, farmers have struggled to plan their crops and manage irrigation for food production. In Burkina Faso, many farmers have resorting ...

  10. Coupling microscale vegetation–soil water and macroscale vegetation–precipitation feedbacks in semiarid ecosystems

    NARCIS (Netherlands)

    Dekker, S.C.; Rietkerk, M.G.; Bierkens, M.F.P.

    2007-01-01

    At macroscale, land–atmosphere exchange of energy and water in semiarid zones such as the Sahel constitutes a strong positive feedback between vegetation density and precipitation. At microscale, however, additional positive feedbacks between hydrology and vegetation such as increase of

  11. The Effect of Breed, Age and Fasting Status on Macro-nutrient ...

    African Journals Online (AJOL)

    Carcasses of 32 male goats matching Conformation Score 3 of the Australian standard for live goat evaluation, were randomly assigned to a 2x2x2 factorial experiment involving two breeds (Sahel, Sokoto Red), two ages (young, mature) and two fasting states (fasted, non-fasted) with four replicates. one and a half ...

  12. Feasibility, safety and effectiveness of combining home based malaria management and seasonal malaria chemoprevention in children less than 10 years in Senegal

    DEFF Research Database (Denmark)

    Tine, Roger C K; Ndour, Cheikh T; Faye, Babacar

    2014-01-01

    Home-based management of malaria (HMM) may improve access to diagnostic testing and treatment with artemisinin combination therapy (ACT). In the Sahel region, seasonal malaria chemoprevention (SMC) is now recommended for the prevention of malaria in children. It is likely that combinations...

  13. New records of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) predation by Brazilian Hemipteran predatory bugs.

    NARCIS (Netherlands)

    Bueno, V.H.P.; Lenteren, van J.C.; Lins, J.C.; Calixto, A.M.; Montes, F.C.; Silva, D.B.; Santiago, L.D.; Pérez, L.M.

    2013-01-01

    The tomato borer Tuta absoluta, native to western South America, is an extremely devastating pest in tomato crops in most of South America, Europe and Africa North of the Sahel, causes yield losses up to 100% and decreases fruit quality in open field and greenhouse crops if control methods are not

  14. Awareness And Compliance Of Women Of Childbearing Age In A ...

    African Journals Online (AJOL)

    Awareness And Compliance Of Women Of Childbearing Age In A Nigerian Urban Community With The TT1 - TT5 Immunization Schedule. ... Sahel Medical Journal ... Only 10.4% of the respondents have received at least two doses of the tetanus toxoid (TT2+) immunization which, fall far below the recommended 80% or ...

  15. Browse Title Index

    African Journals Online (AJOL)

    Items 401 - 450 of 763 ... Vol 9, No 5 (2015), Gumbel Weibull distribution function for Sahel precipitation modeling and predicting: Case of Mali, Abstract PDF. KA Berthe, B Abdramane, S Reichenbach. Vol 7, No 6 (2013), Harmonisation of physical and chemical methods for soil management in Cork Oak forests - Lessons from ...

  16. Author Details

    African Journals Online (AJOL)

    Berthe, KA. Vol 9, No 5 (2015) - Articles Gumbel Weibull distribution function for Sahel precipitation modeling and predicting: Case of Mali Abstract PDF. ISSN: 1996-0786. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms ...

  17. African Journal of Environmental Science and Technology - Vol 9 ...

    African Journals Online (AJOL)

    Gumbel Weibull distribution function for Sahel precipitation modeling and predicting: Case of Mali · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. KA Berthe, B Abdramane, S Reichenbach, 405-412. http://dx.doi.org/10.5897/AJEST2014.1826 ...

  18. Development and calibration of a self-recording cup anemometer for ...

    African Journals Online (AJOL)

    UFUOMA

    Phys. Atmosph., 64: 125-141. Landsea CW, Gray WM (1992). The Strong Association between. Western Sahel Monsoon Rainfall and Intense Atlantic Hurricanes. J. Climate, 5: 435–453. Pitcher GC, Calder D (2000). Harmful algal blooms of the Southern. Benguela current: A review and appraisal of monitoring from 1989 to.

  19. Effects of compost amendment and the biocontrol agent Clonostachys rosea on the development of charcoal rot (Macrophomina phaseolina) on cowpea

    NARCIS (Netherlands)

    Ndiaye, M.; Termorshuizen, A.J.; Bruggen, van A.H.C.

    2010-01-01

    Macrophomina phaseolina is a destructive pathogen causing charcoal rot of cowpea and other crops in the semi- arid areas of the Sahel (north-west Africa). Chemical management is not feasible in conditions of subsistence farming, and the plurivorous nature of the fungus limits the effectiveness of

  20. Economic benefits of combining soil and water conservation measures with nutrient management in semiarid Burkina Faso

    NARCIS (Netherlands)

    Zougmoré, R.; Mando, A.; Stroosnijder, L.; Ouédraogo, E.

    2004-01-01

    Nutrient limitation is the main cause of per capita decline in crop production in the Sahel, where water shortage also limits an efficient use of available nutrients. Combining soil and water conservation measures with locally available nutrient inputs may optimize crop production and economic

  1. Soil nutrient and sediment loss as affected by erosion barriers and nutrient source in semi-arid Burkina Faso

    NARCIS (Netherlands)

    Zougmore, R.; Mando, A.; Stroosnijder, L.

    2009-01-01

    In semi-arid Sahel, soil erosion by water is one major factor accounting for negative nutrient balances in agricultural systems. A field experiment was conducted on a Ferric Lixisol in Burkina Faso to assess the effects of soil and water conservation barriers (stone rows or grass strips of

  2. Analysis of radiosonde data on tropospheric water vapour in Nigeria ...

    African Journals Online (AJOL)

    The analyses of some atmospheric water vapour parameters derived from radiosonde data at the three existing radiosonde stations in Nigeria are reported. The stations essentially represent the climates of the southern (coastal), middlebelt (savannah), and northern (sub-sahel) regions of the country. Monthly means of the ...

  3. All projects related to Canada | Page 18 | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results. Displaying 171 - 180 of 251. Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF) ... Region: Nigeria, North of Sahara, South of Sahara, Canada. Program: Agriculture and Food ... Adapting to the Impacts of Climate Change on Water Resources. Project. Significant gaps ...

  4. Daytime passerine migrants over the Sahara — are these diurnal ...

    African Journals Online (AJOL)

    When crossing the Sahara it was expected that nocturnal migrants would continue their flight into the day. We investigated whether migration taking place in the Sahara during daytime comprises the normal diurnal migrant species or the nocturnal ones prolonging their flight into the day. Birds departing from the Sahel in ...

  5. Identification of potentially competing Afrotropical and Palaearctic ...

    African Journals Online (AJOL)

    Identification of potentially competing Afrotropical and Palaearctic bird species in the Sahel. ... Areas experiencing a seasonal influx of migrants may be expected to have a high potential for competition between resident and migrant populations. Described differences in foraging behaviour and microhabitat selection ...

  6. proprietes hydriques des sols dans deux zones a ecosystemes ...

    African Journals Online (AJOL)

    soils based on land use so as to determine the soil's ability to support certain functions. It analyses the influence of land use ... of hydraulic conductivity to Koalma. Keywords : Tydraulic conductivity; soil texture; land use; degradation; Sahel .... Des études sur les valeurs des NDVI (Normalized. Differentiel Vegetation Index ou ...

  7. 1705-IJBCS-Article-Barthélemy Yelemou

    African Journals Online (AJOL)

    hp

    All rights reserved. Mots clés: Parc agroforestier, mode de gestion, satisfaction des besoins, Vipalogo, Burkina Faso. INTRODUCTION. Depuis trois décennies, le Sahel est confronté à de nombreuses difficultés parmi ..... de service (piliers ou poutres pour les hangars et la toiture des cases et greniers), une vingtaine.

  8. Monitoring land degradation with long-term satellite data in South Africa.

    CSIR Research Space (South Africa)

    Wessels, Konrad J

    2007-01-01

    Full Text Available satellites were analysed and showed that the Sahara desert was not marching southwards into the Sahel, but rather expanded and contracted as a result of interannual variations in rainfall.4 Recently, a number of studies using 20 years of AVHRR NDVI data...

  9. Wars Without Beginning or End

    DEFF Research Database (Denmark)

    Walther, Olivier; Leuprecht, Christian; Skillicorn, David

    This article examines the structure and spatial patterns of violent political organizations in the Sahel-Sahara, a region characterized by growing political instability over the last 20 years. Drawing on a public collection of disaggregated data, the article uses network science to represent...

  10. The Sign Language Situation in Mali

    Science.gov (United States)

    Nyst, Victoria

    2015-01-01

    This article gives a first overview of the sign language situation in Mali and its capital, Bamako, located in the West African Sahel. Mali is a highly multilingual country with a significant incidence of deafness, for which meningitis appears to be the main cause, coupled with limited access to adequate health care. In comparison to neighboring…

  11. Insistent Dryland Narratives: Portraits of Knowledge about Human ...

    African Journals Online (AJOL)

    The drylands in the West African Sahel region have, since the catastrophic drought event in the 1970s, been a focal point of interest in the cross field between environmental research, knowledge systems and policy intervention strategies. Major international institutions, agencies and conventions have played an important ...

  12. a strategy to improve the quality of the electric power produced

    African Journals Online (AJOL)

    Menga F. D, Djongyang N, Danwé R, Tchinda R and Zaatri A

    2016-05-01

    May 1, 2016 ... 2Department of Material Processing, Architecture and Habitat, The Higher Institute of the Sahel,. University of Maroua ... If the permanence of the electrical energy produced by a wind turbine can be assured, its ... made a comparative study of various wind turbine structures and impacts of disturbances on.

  13. Accès à l'eau pour les agricultrices sahéliennes: enjeux pour une ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Langaa Research and Publishing Common Initiative Group. 6 mars 2014. ISBN : 9789956791217. 194 pages. This collective work looks at the origins, examples, and consequences of the gender divide with regards to the access, use, and control of water in the Sahel. The book draws on the IDRC-funded research project, ...

  14. Densities of Palearctic warblers and Afrotropical species within the ...

    African Journals Online (AJOL)

    Despite this, there is an almost complete lack of data on the density and distribution of Palearctic migrants wintering in the Sahel and whether they have the same habitat requirements as similar, resident Afrotropical species. We measured the density of five species of Palearctic warblers (Sylviidae) and 10 species of ...

  15. South of Sahara | Page 10 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Read more about Political Participation of Young Women in Francophone West Africa: Forms, Issues and Public Policies. Language English. Read more about Integrated Nutrient and Water Management for Sustainable Food Production in the Sahel (CIFSRF). Language English. Read more about Forum africain de la ...

  16. Sokoto Journal of Veterinary Sciences - Vol 10, No 2 (2012)

    African Journals Online (AJOL)

    Prevalence and antibiotic susceptibility of Listeria monocytogenes in raw milk from cattle herds within Sokoto Metropolis, Nigeria · EMAIL FREE FULL TEXT EMAIL ... Induction of estrus in Sahel goats using Fluorogestone Acetate (FGA) sponges and Equine Chorionic Gonadotrophin (ECG) · EMAIL FREE FULL TEXT EMAIL ...

  17. Examining disadoption of gum arabic production in Sudan

    NARCIS (Netherlands)

    Rahim, A.; Ruben, R.; Ierland, van E.C.

    2008-01-01

    Gum arabic production in Sudan has developed over the years in a well-established traditional bush-fallow system in which the gum tree (Acacia senegal) is rotated with annual crops. Following the Sahel drought, the gum area has suffered from deforestation and gum production has declined. Several

  18. Early lambing – kidding, prolificacy and twinning in the Nigerian ...

    African Journals Online (AJOL)

    %) was the most prolific, followed by WAD (4.64%) and Red Sokoto goat (3.86%). ... With the breeds of goat, WAD goat (3.31%) had more occurrence of twinning followed by Red Sokoto (2.88%), while Sahel goat had the lowest occurrence of ...

  19. Encapsulating knowledge from local documents

    DEFF Research Database (Denmark)

    Reenberg, Anette; Moussa, Ibarhim Bouzou; Some, Bernadette

    Abstract Environmental change in the West African Sahel, including land cover change, has been a prominent issue in sustainability and development debates and research for the last half century. This paper provides a reminder that historical changes in the use of land resources are embedded in a ...

  20. Phenotypic Characterization of the Bunaji Cattle Breed in Oyo State ...

    African Journals Online (AJOL)

    The phenotypic traits observed indicated that Bunaji breed of cattle were predominantly white (78%) in color, while grey and pied are less common (2 and 1% respectively). Ear type was medium and erect with dewlap and penile sheath being prominent. Keywords: Phenotypic, characterization, Bunaji cattle. Sahel Journal ...

  1. The effectiveness of medroxyprogesterone acetate (MAP) in ...

    African Journals Online (AJOL)

    Oestrus was synchronized in crossbred ewes (Djallonke x Sahel F2 generation) on the Ghana Government /UNDPI FAO Sheep and Goat Project Farm at Ejura. Medroxyprogesterone acetate (MAP), 60 mg, was applied in an antibiotic-treated intravaginal sponge and allowed to remain for 14 days. Pregnant mare serum ...

  2. Bushland in Mindif Region, Cameroon : functions, decline, context and prospects

    NARCIS (Netherlands)

    Wassouni,

    2006-01-01

    Everybody still knows the images of hunger and drought in the dry zones of Africa (the Sahel). These last years the situation for the millions of people living there has stabilised due to the fact that rainfall has not failed. But what about the future? The population is still growing rapidly, and

  3. Factors affecting birth weight, litter size and survival rates of goats in ...

    African Journals Online (AJOL)

    For instance, the Sahel Goat (SG) doe has the largest birth weight followed by Red Sokoto (RS) and least the West African Dwarf (WAD) goats. However, litter size was significantly (p<0.001) highest in WAD followed by RS and lowest in SG does. Body condition score of does significantly (p<0.001) influenced both birth ...

  4. adoption of improved aquaculture practices by shrimp farmers in ...

    African Journals Online (AJOL)

    Dr.Adesope

    ABSTRACT. Crop production in the Sahel is limited by nutrients availability. The study aimed to estimate the contribution of avifauna, crop rotation and trees to soil fertility and crop production improvement. Pot experiment was carried out with soils sampled in Faidherbia albida parklands in cotton production zone of West ...

  5. Vom work Book Journal, 2011 2nd Edition Victor

    African Journals Online (AJOL)

    USER

    SUMMARY. A retrospective cohort study on slaughter–mediated pregnancy wastage in abattoirs and slaughter points record from January 1998 to December 2009 in the Sahel region of Nigeria revealed an incidence of 22.78 % in sheep and. 17.88 % in goats. During the study period, a total of. 440,917 sheep and 826,435 ...

  6. Effect of rain drop washes on soil fertility in cotton production zone of ...

    African Journals Online (AJOL)

    Crop production in the Sahel is limited by nutrients availability. The study aimed to estimate the contribution of avifauna, crop rotation and trees to soil fertility and crop production improvement. Pot experiment was carried out with soils sampled in Faidherbia albida parklands in cotton production zone of West Burkina Faso.

  7. All projects related to | Page 500 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2007-10-23

    Project. Climate change poses a real challenge to communities of the Sahel, that of surviving in a fragile environment undergoing rapid mutation. Start Date: October 23, 2007. End Date: March 21, 2011. Topic: CLIMATE CHANGE, ADAPTATION TO CHANGE, DISASTER PREPAREDNESS, DISASTER MANAGEMENT, ...

  8. ISSN 2073-9990 East Cent. Afr. J. surg. (Online)

    African Journals Online (AJOL)

    dell

    This is attributed to the association with hepatitis B, of which the presence of its surface antigen is common in these populations in up to 80% of cases1,2,3. Maiduguri is a city in the. Sahel savannah near Lake Chad in Nigeria where a previous study showed that 84.4% of controls had evidence of hepatitis B virus infection.

  9. Micro-element contents of roselle ( Hibiscus sabdariffa L.) at different ...

    African Journals Online (AJOL)

    In the western Sahel, leaves of Roselle (Hibiscus sabdariffa) have considerable economic importance because of their nutritional and medical uses. These plant organs are used to supplement nutrients provided by cereals such as millet and sorghum. However, there is a lack of information on the nutrient composition of ...

  10. All projects related to | Page 90 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Improving quality of maternal health care for indigenous women in Argentina, Mexico, and Peru. Project ... Financial Services and the Deployment of Agricultural Innovations in the Sahel. Project. Over the past 20 ... Topic: CROP YIELD, SMALL FARMS, FINANCING, WEST AFRICA, AGRICULTURE, Food security. Region: ...

  11. Modelling functional and structural impact of non-synonymous ...

    African Journals Online (AJOL)

    A 310-bp fragment of exon 2 of the DQA1 gene was amplified and sequenced in 27 unrelated animals that are representative of three major Nigerian goat breeds (nine each of West African Dwarf, Red Sokoto, and Sahel of both sexes) using genomic DNA. Forty-two nsSNPs were identified from the alignment of the ...

  12. Review Article: Anorectal abscesses: a review of presentation and ...

    African Journals Online (AJOL)

    Conclusion: There is the need for awareness of the various modes of presentations and management of this entity. It should also be considered as a differential diagnosis of causes of low back and pelvic pains to stem the consequences associated with mis-diagnosing and treating this condition. Sahel Medical Journal Vol.

  13. Estimation of rainfall inputs and direct recharge to the deep unsaturated zone of southern Niger using the chloride profile method.

    NARCIS (Netherlands)

    Bromley, J.; Edmunds, W.M.; Fellman, E.; Brouwer, J.; Gaze, S.R.; Sudlow, J.; Taupin, J.D.

    1997-01-01

    An estimate of direct groundwater recharge below a region of natural woodland (tiger bush) has been made in south-west Niger using the solute profile technique. Data has been collected from a 77 m deep well dug within the study area covered by HAPEX-Sahel (Hydrological and Atmospheric Pilot

  14. ( Hibiscus sabdariffa L.) from Niger

    African Journals Online (AJOL)

    Roselle is an important part of the human diet in many countries, particularly in the Sahel zone of West Africa. The leaves of Roselle are consumed as a green vegetable and in sauce. Nevertheless, little attention has been paid to their nutrient composition at different stages of plant growth. Therefore, the experiment was ...

  15. Browse Title Index

    African Journals Online (AJOL)

    Items 151 - 200 of 478 ... Vol 31, No 4 (2010), Effect of Maternal Alcohol Consumption on Epididymal Growth in Neonatal Mice, Abstract PDF. JE Onu, DN Ezeasor, EC Ihemelandu. Vol 38, No 1 (2017), Effect of normal saline and oviplus® on epididymal sperm quality and relationship with testicular morphometry in Sahel bucks ...

  16. Nigerian Veterinary Journal - Vol 38, No 1 (2017)

    African Journals Online (AJOL)

    Effect of normal saline and oviplus® on epididymal sperm quality and relationship with testicular morphometry in Sahel bucks · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. M.M. Bukar, S Ochai, J Stephen, D Iliyasu, 4-12 ...

  17. Browse Title Index

    African Journals Online (AJOL)

    Items 601 - 650 of 683 ... Vol 62, No 4 (2014), Testicular and related size evaluations in Nigerian Sahel goats with optimal cauda epididymal sperm reserve, Abstract. Y Abba, IO Igbokwe. Vol 60, No 1 (2012), Testicular Morphometry and Histology of Male Wistar Rats and Gestational Pattern of Female Wistar Rats Treated with ...

  18. Prediction models for estimating foliar and fruit dry biomasses of five ...

    African Journals Online (AJOL)

    Prediction models for estimating foliar and fruit dry biomasses of five Savannah tree species in the West African Sahel. ... Direct evaluation of leaf and fruit biomass through destructive method was used to estimate the biomasses of fruits and leaves. Diameter at breast height and crown diameter were candidate explanatory ...

  19. Changes In Udder Size And Liveweight Of West African Dwarf, Red ...

    African Journals Online (AJOL)

    Changes in udder size and liveweight (LWT) of ten West African Dwarf (WAD), three Red Sokoto (RS) and three Sahel goats during lactation and their phenotypic relationship with partial daily milk yield (PDM) were studied. Udder length (UL), udder width (UW), udder circumference (UC). udder volume (UV), distance ...

  20. Publications | Page 614 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 6131 - 6140 of 6371 ... Sharing and Writing Workshop, Khaya Lembali Durban, 2 - 15 June 2006 : provisional programme (restricted access) ... history of Niger and the Sahel. Only now is integrated farming and livestock production coming to their region, and it represents an essential step toward raising and sustaining.

  1. The Theoretical Milieu: Fulani herder-indigene conflicts in Tallensi ...

    African Journals Online (AJOL)

    herders' and indigenes' notions of space and place, I extend this knowledge by suggesting that much as the migrations are responses to deteriorating environmental conditions in the Sahel, a nomadic spatial.frame of reference enables herders to access and settle in others' territory despite almost continual resistance to ...

  2. Download this PDF file

    African Journals Online (AJOL)

    Embryo transfer Cryopreservation and cloning for ex-situ management of genetic diversity (Jimenez-Rabadan et al., 2016). It has been shown that strong relationship existeds between the scrotal circumference and the testicular as well as the epididymal parameters in Sahel goats (Oyeyemi et al.,. 2012). In addition, it was ...

  3. Factors livestock and milking associated with risk of mastitis in cattle ...

    African Journals Online (AJOL)

    This study was carried out in the Sahel of Tunisia (Monastir region) on a sample covering 40 cattle herd's type above ground. We deduced the mastitis risk factors during the survey during visits for breeding and milking as well as from morphological and hygienic cow's assessments. The data's descriptive analysis has ...

  4. Household triggers of bronchospasm in children aged less than two ...

    African Journals Online (AJOL)

    Household triggers of bronchospasm in children aged less than two years with hyperreactive airway: a multicentre experience. ... Sahel Medical Journal ... presenting with cough and breathlessness of sudden onset with audible wheeze were screened historically for the trigger factors of bronchospasm in their environment.

  5. Author Details

    African Journals Online (AJOL)

    Akpede, G. O.. Vol 78, No 11 (2001): - Articles Nutritional rickets in young Nigerian children in the Sahel Savanna Abstract PDF. ISSN: 0012-835X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

  6. Social Memory of Short-term and Long-term Variability in the Sahelian Climate

    Science.gov (United States)

    Roderick J. McIntosh

    2006-01-01

    The 170,000 km2 interior floodplain of the Middle Niger (Mali) is a tight mosaic of alluvial and desert microenvironments. The interannual to intermillennial climate change profiles of this fluvial anomaly thrust deep into the Sahel and southern Sahara are masterpieces of abrupt phase shifts and unpredictability. Response has been of two kinds. The Office du Niger was...

  7. The role of climatic scenarios in farmers' adjustments to climatic ...

    African Journals Online (AJOL)

    In order to assess the potential effects of drought on agricultural yields in the West African Sahel, the study created scenarios of future climatic changes based on arbitrary data and analogues of historical climatic data. The results indicated that a possible climatic change which involves up to 50% reduction in the

  8. Overview of restoration and management practices in the degraded ...

    African Journals Online (AJOL)

    The highest deforestation and forest degradation rates in Africa occur in the dry forests and woodlands where pressure for land is increasing, poverty is rampant, livelihood options are few and climate change effects are severe. This paper examines factors that cause land and forest degradation in the Sahel and dry forests ...

  9. Coupling microscale vegetation-soil water and macroscale vegetation-precipitation feedbacks in semiarid ecosystems

    NARCIS (Netherlands)

    Dekker, S.C.; Rietkerk, M.; Bierkens, M.F.P.

    2007-01-01

    At macroscale, land¿atmosphere exchange of energy and water in semiarid zones such as the Sahel constitutes a strong positive feedback between vegetation density and precipitation. At microscale, however, additional positive feedbacks between hydrology and vegetation such as increase of infiltration

  10. Characterization of three invading aquatic plants in Burkina Faso ...

    African Journals Online (AJOL)

    ... pinnata and C. demersum and 4 units for T. australis. The fonio and the maize biomass production were not significantly different for substrates. The maize yield benefit was highest for C. demersum. The three aquatic invading plants represent a high potential for crop production in the Sahel. However, the long term effects ...

  11. The influence of sex on the haematological values of apparently ...

    African Journals Online (AJOL)

    Blood samples were collected from fifty apparently healthy adult Sahel goats, twenty five each of male and female in Maiduguri to assess the influence of sex on their haematology. The red blood cell (RBC) counts, white blood cell (WBC) counts, haemoglobin (Hb) concentration, packed cell volume (PCV), platelet counts, ...

  12. Co-evolutionary scenarios of intensification and privatization of resource use in rural communities of south-western Niger

    NARCIS (Netherlands)

    Rovere, La R.; Hiernaux, P.; Keulen, van H.; Schiere, J.B.; Szonyi, J.A.

    2005-01-01

    Agricultural production in the semi-arid agro-ecosystems of the Sahel centres on cereal staple crops and pastoralism with increasing crop-livestock integration. Animals mobilize soil fertility through manure production, graze crop by-products, and transfer nutrients from distant pastures to cropped

  13. Survival of enteric bacteria in source-separated human urine used ...

    African Journals Online (AJOL)

    MAKAYA

    temperature, ammonia and pH. The temperature depends on the storage conditions and the climate. Because of high temperatures regularly reported in tropical regions especially in Sahel (Ouédraogo et al.,. 2007), urine storage time can be shortened, as compared to temperate regions, where storage times of 2-6 months.

  14. Strategies To Accommodate The Rising Tide Of Immigration And Human Flow: The Case of Morocco

    Science.gov (United States)

    2015-12-11

    20 percent done… many can work to pay off for the rest of the journey, including the bribes necessary for the cops and officials…” said a Nigerian ...and fisheries across the Sahel and West Africa.43 However, the challenge is much bigger than the ambitions and resources available. There needs

  15. Advancing Stability and Reconciliation in Guinea-Bissau: Lessons from Africa’s First Narco-State

    Science.gov (United States)

    2013-06-01

    visited Bissau to coordinate trans-Sahel drug trafficking with Latin American criminal networks.9 Nigerian criminal syndicates, similarly, have... fisheries , and likely oil, Guinea-Bissau is a choice target for unscrupulous actors who often seek to take advantage of a fragile state with

  16. Maternal Perception of Teething in Infancy: Implications for Health ...

    African Journals Online (AJOL)

    The need to expand the scope of health education at under-five clinics in this locality is evident. It is recommended that information on childhood dentition should be incorporated in health-education sessions in order to correct the erroneous perception of mothers on the subject. Sahel Medical Journal Vol.7(1) 2004: 21-24 ...

  17. Adipose tissue tumours in Port Harcourt: (a ten year review) | Seleye ...

    African Journals Online (AJOL)

    Though not given much attention in medical practice and in literature, they pose cosmetic problems. The location and size of the tumour determined the symptoms which range from dyspnea to a feeling of fullness and discomfort in motion. Keywords: lipoma, liposarcoma, age, gender, site, cosmetics. Sahel Medical Journal ...

  18. Response of high yielding rice varieties to NaCl salinity in ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-11-05

    Nov 5, 2008 ... in the experiment include: Dasht, Khazar, Kadous, Nemat, Neda,. Fajr, Shafagh and Sahel. To obtain the accurate result and exclude any unwanted and interfering variable in the environment and to minimize their effects, the experiment was conducted in a highly controlled greenhouse. The greenhouse ...

  19. West African Monsoon Decadal Variability and Surface-Related Forcings: Second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)

    Science.gov (United States)

    Xue, Yongkang; De Sales, Fernando; Lau, William K-M; Boone, Aaron; Kim, Kyu-Myong; Mechoso, Carlos R.; Wang, Guiling; Kucharski, Fred; Schiro, Kathleen; Hosaka, Masahiro; hide

    2016-01-01

    The second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II) is designed to improve understanding of the possible roles and feedbacks of sea surface temperature (SST), land use land cover change (LULCC), and aerosols forcings in the Sahel climate system at seasonal to decadal scales. The WAMME II strategy is to apply prescribed observationally based anomaly forcing, i.e., idealized but realistic forcing, in simulations by climate models to test the relative impacts of such forcings in producingamplifying the Sahelian seasonal and decadal climate variability, including the great 20th century drought. This is the first multi-model experiment specifically designed to simultaneously evaluate relative contributions of multiple external forcings to the Sahel decadal precipitation anomalies between the 1980s and the 1950s that is used to characterize the Sahel 1980s drought in this study. The WAMME II models have consistently demonstrated that SST is the major contributor to the 20th century Sahel drought. Under the influence of the maximum possible SST forcing, WAMME II model ensemble mean can produce up to 60 of the precipitation difference between the 1980s and the 1950s. The present paper also delineated the role of SSTs in triggering and maintaining the Sahel drought. The impact of SSTs in individual oceans is also examined and consensus and discrepancies are reported. Among the different ocean basins, the WAMME II models show the consensus that the Indian Ocean SST has the largest impact on the precipitation temporal evolution associated with the ITCZ movement before the WAM onset while the Pacific Ocean SST greatly contributes to the summer WAM drought. This paper also compares the SST effect with the LULCC effect. Results show that with prescribed land forcing the WAMME II model ensemble mean produces about 40 of the precipitation difference between the 1980s and the 1950s, which is less than the SST contribution but still of first order

  20. Increase in Carbon Storage for Sahelian Vegetation between 1982-1999

    Science.gov (United States)

    Seaquist, J.; Olsson, L.

    2004-05-01

    The Sahel belt of north Africa has been flagged as a hotspot for land cover change. For the period 1982-1999, Eklundh and Olsson (2003) identify large areas of strong, positive trends in NOAA AVHRR-derived NDVI (Normalized Difference Vegetation Index). This discovery implies that the Sahel may play a significant role in the tropical carbon cycle. The NDVI is a quantitative indicator of relative vegetation amount, and has traditionally been used as a surrogate measure of NPP (Net Primary Production), often expressed in terms of carbon content. It cannot, however, quantify absolute NPP amounts. The goal of our work is to estimate the magnitude of the increase in carbon storage in the vegetation of the Sahel for the period 1982-1999 using a light-use efficiency model. A light-use efficiency model encapsulates the essence of the plant growth process at an aggregate level; solar radiation is absorbed by plants to provide energy for photosynthesis, while soil moisture controls the efficiency of light usage. Our model runs at a monthly time-step (the hydrological component has a quasi-daily time-step), and is driven by data from the NOAA AVHRR (Seaquist et al., 2003). The model has undergone sensitivity testing, and various sub-components of the model have been validated. After implementation, monthly NPP surfaces were summed to yield total growing season (May to October) amounts, expressed as carbon content, for the 17-year period. Trends were estimated by fitting linear functions to the data on a pixel-by-pixel basis using ordinary least squares regression. Only those trends that were statistically significant at the 95% confidence interval were mapped. The results show a conspicuous band of moderate to strong increase (25-75%) in NPP across the Sahel belt, especially throughout Mali, Burkina Faso, northern Nigeria, and into Central Chad. The trends become weaker further east, before they intensify through central and southern Sudan. Our calculations show that the

  1. On the Saharan Heat Low Bias in CMIP5 Models and its Relationship with Tropical Precipitation and Global Energy Transport Biases

    Science.gov (United States)

    Dixon, Ross Donnelly

    Representing the West African Monsoon (WAM) is a major challenge in climate modeling because of the complex interaction between local and large scale mechanisms. Comparison of the Saharan heat low (SHL) representation in both CMIP5 simulations and reanalyses shows large biases in the strength and location of the climatological SHL. Both coupled and uncoupled climate models that place the SHL farther to the north are associated with increased precipitation across the Sahel. Further, the northward SHL placement is also associated with a northward shift in the Atlantic ITCZ in coupled models, but an eastward shift in uncoupled models. This statistical relationship informs three causal hypotheses: i) the north/south shift in the Atlantic ITCZ causes a corresponding north/south shift in the SHL and increase in Sahel precipitation, ii) the location of the Atlantic ITCZ, the location of the SHL, and the strength of Sahel precipitation are all responding to some external forcing, iii) The north/south shift in the SHL causes an increase in Sahel precipitation and a north/south shift in the Atlantic ITCZ. In order to test these hypotheses, three perturbation experiments are performed using the Community Earth System Model (CESM). We find that when the Atlantic ITCZ is forced locally, there is no coherent response in West African climate. However, when the Atlantic ITCZ is forced through altering the cross equatorial energy transport, the SHL and Sahel precipitation respond to the large scale forcing. Similarly, when the SHL strength is forced directly, there is a weak but robust increase in Sahel precipitation and a northward shift in the Atlantic ITCZ. These experiments show that global scale biases have an important impact on biases local to the West African Monsoon and that there is a feedback from West African climate onto the Atlantic ITCZ. The importance of global scale forcing in understanding local features of tropical Atlantic and West African precipitation

  2. Staying with the system

    DEFF Research Database (Denmark)

    Rasmussen, Laura Vang; Nielsen, Jonas Østergaard

    2014-01-01

    -environmental system framework in the journal may be attributed to Reenberg’s theoretical agenda as well as a new international stream of research joining the human and environmental sciences in an interdisciplinary effort. Hence, it is also shown how Reenberg’s theoretical agenda have influenced scholars trying....... Taking papers published in Geografisk Tidsskrift-Danish Journal of Geography as an example we show how scholars have moved from treating aspects of the Sahelian droughts according to the traditional natural-social science divide towards a much more coupled manner. This rise of the coupled human......Scholars have studied the Sahel intensely since major droughts hit the region in the early 1970s. One of the most persistent of these in terms of both volume and time span is Anette Reenberg. In this paper we explore her studies of the Sahel published in peer-reviewed journals and their impact over...

  3. Analysis of trends in the Sahelian 'rain-use efficiency' using GIMMS NDVI, RFE and GPCP rainfall data

    DEFF Research Database (Denmark)

    Fensholt, Rasmus; Rasmussen, Kjeld

    2011-01-01

    Rain-use efficiency (RUE; the ratio of vegetation productivity to annual precipitation) has been suggested as a measure for assessing land degradation in arid/semi-arid areas. In the absence of anthropogenic influence, RUE has been reported to be constant over time, and any observed change may...... therefore be attributed to non-rainfall impacts. This study presents an analysis of the decadal time-scale changes in the relationship between a proxy for vegetation productivity (SNDVI) and annual rainfall in the Sahel-Sudanian zone of Africa. The aim is to test the quality of data input and the usefulness....... An alternativemethod identify temporal trends in residuals of SNDVI, after regressing it against annual rainfall, is tested, yet is shown to be useful only where a high correlation between SNDVI and annual rainfall exists. For the areas in the Sahel-Sudanian zone forwhich this condition is fulfilled, trend analyses...

  4. West African monsoon decadal variability and surface-related forcings: second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yongkang; de Sales, Fernando; Lau, Willliam; Boone, Aaron; Kim, Kyu-Myong; Mechoso, C. R.; Wang , Guiling; Kucharski, Fred; Schiro, Kathleen; Hosaka, Masahiro; Li, Suosuo; Druyan, Leonard M.; Sanda, Ibrah S.; Thiaw, Wassila; Zeng, Ning; Comer, Ruth E.; Lim, Young-Kwon; Mahanama, Sarith; Song, Guoqiong; Gu, Yu; Hagos, Samson M.; Chin, Mian; Schubert, Siefried; Dirmeyer, Paul; Leung, Lai-Yung; Kalnay, Eugenia; Kitoh, Akio; Lu, Cheng-Hsuan; Mahowald, N. M.; Zhang, Zhengqiu J.

    2016-06-13

    The Sahel climate system had experienced one of the strongest interdecadal climate variabilities and the longest drought on the planet in the twentieth century. Most modeling studies on the decadal variability of the Sahel climate so far have focused on the role of anomalies in either sea surface temperature (SST), land surface processes, or aerosols concentration. The Second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II) is designed to improve understanding of the possible roles and feedback of SST, land use land cover change (LULCC), and aerosols forcings in the Sahel climate system at seasonal to decadal scales. The WAMME II strategy is to apply observationally based anomaly forcing, i.e., “idealized but realistic” forcing, in simulations by general circulation models’ (GCMs) and regional climate models’ (RCMs) to test the relative impacts of such forcings in producing/amplifying the Sahelian seasonal and decadal climate variability, including the 20th century drought. To test individual ocean’s SST effect, a special approach in the experimental design is taken to avoid undermine its effect. This is the first multi-model experiment specifically designed to simultaneously evaluate relative contributions of multiple-external forcings to the Sahel drought. This paper presents the major results and preliminary findings of the WAMME II SST experiment, including each ocean’s contribution to the global SST effect, as well as comparison of the SST effect with the LULCC effect. The common empirical orthogonal functions and other analyses are applied to assess and comprehend the discrepancies among the models. In general, the WAMME II models have reached a consensus on SST’s major contribution to the great Sahel drought and show that with the maximum possible SST forcing, it can produce up to 60% of the absolute amount of precipitation difference between the 1980s and the 1950s. This paper has 3 also delineated the role of SSTs in

  5. Vegetationsveränderungen in westafrika -spiegel von klimawandel und landnutzung

    DEFF Research Database (Denmark)

    Brandt, Martin Stefan; Paeth, Heiko; Samimi, Cyrus

    2013-01-01

    vegetation changes, mainly forest losses have happened. Since the 90ies the precipitation stabilized somewhat and a greening trend can be observed. Both paradigms, desertification and greening, tend to neglect regional and local differences. These differences are often decoupled from rainfall and are linked......Western Africa has been discussed as a hot spot of environmental change. In the 1970ies and 80ies a drastic decrease in precipitation and severe droughts occurred in the Sahel. The degradation of the vegetation led to the desertification paradigm. But also in wetter regions south of the Sahel...... to land use practices. The article gives an overview about regional trends of vegetation and climate change and emphasize on decoupling precipitation and vegetation. Local examples show how land use leads to diverse vegetation developments....

  6. Variabilité morphologique de Balanites aegyptiaca (L.) Del. dans la ...

    African Journals Online (AJOL)

    Dans le Sahel tchadien, le Balanites aegyptiaca est un arbre de grandes importances socioéconomiques pour les populations. L'objectif de l'étude a été de développer les stratégies de conservation et d'utilisation durable des ressources génétiques de l'espèce. Une enquête socio-économique et un inventaire botanique ...

  7. Possibilités de bouturage chez Maerua crassifolia Forssk ...

    African Journals Online (AJOL)

    AKA Boko

    Rencontrée de part et d'autre du Sahara et dans la péninsule arabique, en Afrique de l'Ouest et du Centre [3 ... En Afrique de l'Ouest, l'espèce est rencontrée principalement au Sahel, en zone sylvo- pastorale. Au Ferlo ..... [15] - A. YENIKOYE, Etude de l'endocrinologie sexuelle et de la croissance folliculaire chez la brebis ...

  8. 2729-IJBCS-Article-Bechir Brahim

    African Journals Online (AJOL)

    hp

    Dans le Sahel tchadien, le Balanites aegyptiaca est un arbre de grandes importances socio- économiques pour les populations. L'objectif de l'étude a été de développer les stratégies de conservation et d'utilisation durable des ressources génétiques de l'espèce. Une enquête socio-économique et un inventaire botanique ...

  9. Overlooked Mountain Rock Pools in Deserts Are Critical Local Hotspots of Biodiversity

    OpenAIRE

    Vale, C?ndida Gomes; Pimm, Stuart L.; Brito, Jos? Carlos

    2015-01-01

    Background The world is undergoing exceptional biodiversity loss. Most conservation efforts target biodiversity hotspots at large scales. Such approach overlooks small-sized local hotspots, which may be rich in endemic and highly threatened species. We explore the importance of mountain rock pools (gueltas) as local biodiversity hotspots in the Sahara-Sahel. Specifically, we considered how many vertebrates (total and endemics) use gueltas, what factors predict species richness, and which guel...

  10. Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

    KAUST Repository

    Bangalath, Hamza Kunhu

    2016-06-13

    Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

  11. Ocean impact on decadal Atlantic climate variability revealed by sea-level observations

    OpenAIRE

    McCarthy, Gerard D.; Haigh, Ivan D.; Hirschi, Joël J.-M.; Grist, Jeremy P.; Smeed, David A.

    2015-01-01

    Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall1, European summer precipitation2, Atlantic hurricanes3 and variations in global temp...

  12. Movimenti contadini, spazi rurali e genere: il caso del Fondo Itali-CILSS in Senegal

    OpenAIRE

    Migliardi, Agnese

    2013-01-01

    African rural spaces – and namely their capabilities and vocation to produce – have recently come up again in international debates of academics, politicians, civil society and development practitioners. The current food crisis in the Sahel region (and the past one of 2008), the growing investments in bio-fuels and the so-called “land-grab”, the gender inequalities in accessing natural and productive resources, brought the attention back to the challenges facing African rural economies, na...

  13. [Mortality levels very elevated again. Seminar on dissemination of EMIS/Burkina findings].

    Science.gov (United States)

    Mbacke, C; Bellal, M O

    1988-09-01

    A national seminar was held in Bobo-Dioulasso, Burkina Faso, in August 1988 to disseminate the results of the Survey of Infant Mortality in the Sahel (EMIS). The seminar was organized by the National Institute of Statistics and Demography and funded by the Center for Studies and Research on Population (CERPOD). Various themes were discussed, including the development of surveys on infant and child mortality, maternal-child health policies, contraceptive knowledge and practice and its impact on child survival, and the principal causes of morbidity and mortality among children. The participants adopted a number of resolutions and requested assistance from CERPOD for a more detailed analysis of the survey data, a survey of health and demography covering the entire nation of Burkina Faso, and a regional seminar in Ouagadougou on analysis of the 2nd series of censuses in the Sahel. The EMIS surveys were conducted in 5 urban and 1 rural site in the Sahel. The rural survey was in the region of Thies, Senegal. 4 urban surveys were in Burkina Faso and 1 was in Bamako, Mali. Information was gathered through home visits in the 2 years following the child's birth on infant and early childhood mortality, the mother's use of the health system, and infant feeding practices. Despite numerous errors in data collection, the results show that infant mortality is still very high among children in the Sahel, even in urban areas. There were 13,421 births in the 4 urban areas of the Burkina Faso study. There were 88 deaths per 1000 births in the 1st year and 125 in the 2nd year. In Bamako, Mali, there were 12,114 births, 91 deaths per 1000 births in the 1st year and 122 in the 2nd year. In rural Senegal there were 4987 births, 113 deaths per 1000 births in the 1st year, and 172 in the 2nd year.

  14. Frequency of extreme Sahelian storms tripled since 1982 in satellite observations

    Science.gov (United States)

    Taylor, Christopher M.; Belušić, Danijel; Guichard, Françoise; Parker, Douglas J.; Vischel, Théo; Bock, Olivier; Harris, Phil P.; Janicot, Serge; Klein, Cornelia; Panthou, Gérémy

    2017-04-01

    The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense storms—mesoscale convective systems (MCSs)—poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in ‘extreme’ daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming

  15. Journal of Applied Biosciences - Vol 107 (2016)

    African Journals Online (AJOL)

    Variation de la réponse physiologique et agronomique du niébé (Vigna unguiculata L.Walp) à différentes dates de semis au Burkina Faso · EMAIL FREE FULL ... la production agricole au Sahel : perceptions paysannes sur la double riziculture et les variétés de riz utilisées sur les aménagements hydro - agricoles au Niger ...

  16. SIGAR Special Inspector General for Afghanistan Reconstruction

    Science.gov (United States)

    2017-10-30

    cost of [the] war.”548 ECONOMIC PROFILE The IMF estimated Afghanistan’s real (net of inflation ) gross domestic product (GDP), excluding opium, to...the IMF projected inflation of 5.5%.558 According to the World Bank, exchange rates and global prices exert a significant impact on import-dependent...Robert, W. Gillam, Robert Mondial Defence Systems Ltd Mondial Defense Systems USA LLC Mondial Logistics Khan, Adam Khan, Amir, a.k.a. “Amir Khan Sahel

  17. Étude de la dynamique de la pauvreté et de la dégradation des sols ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au Sahel, la pauvreté et la dégradation des sols sont des problèmes sérieux et interdépendants. La dégradation des sols cause un ralentissement de la productivité agricole actuelle et est une forme de " désépargne " du capital naturel qui aura une incidence néfaste sur la production et les revenus de demain. Mais, s'il ...

  18. L'économie de la gestion des risques en zone semi-aride

    NARCIS (Netherlands)

    Dijk, van J.W.M.; Tielekes, E.; Schlecht, E.; Hiernaux, P.

    2001-01-01

    Toute forme de gestion ou d'aménagement des ressources fourragères pour les éleveurs dans la zone semi-aride au Sahel commence obligatoirement par l'appréciation d'un certain nombre de variables et notamment leur variabilité dans l'espace et dans le temps. Cette variabilité est la source d'une vaste

  19. State of the Climate in 2016

    Energy Technology Data Exchange (ETDEWEB)

    Blunden, Jessica; Arndt, Derek S.

    2017-08-01

    West Africa refers to the region between 17.5°W (eastern Atlantic coast) and ~15°E (along the western border of Chad) and north of the equator (near Guinean coast) to about 20°N. It is divided into two climatically distinct subregions; the semiarid Sahel region (north of about 12°N) and the relatively wet Coast of Guinea region to the south.

  20. Integrated NDVI images for Niger 1986-1987. [Normalized Difference Vegetation Index

    Science.gov (United States)

    Harrington, John A., Jr.; Wylie, Bruce K.; Tucker, Compton J.

    1988-01-01

    Two NOAA AVHRR images are presented which provide a comparison of the geographic distribution of an integration of the normalized difference vegetation index (NDVI) for the Sahel zone in Niger for the growing seasons of 1986 and 1987. The production of the images and the application of the images for resource management are discussed. Daily large area coverage with a spatial resolution of 1.1 km at nadir were transformed to the NDVI and geographically registered to produce the images.

  1. Biogeography and conservation of viperids from North-West Africa : an application of ecological niche-based models and GIS

    OpenAIRE

    Brito, J. C.; Fahd, S.; Geniez, P.; Martinez-Freiria, F.; Pleguezuelos, J. M.; Trape, Jean-François

    2011-01-01

    North-West Africa is an outstanding region to study biogeographic patterns in biodiversity distribution. This study identifies biogeographic affinities and areas of probable occurrence for seven viperid snakes through the combination of high resolution presence data and environmental factors. Vipers exhibited distinct biogeographical affinities: Bitis arietans was mostly found along savannahs, Echis leucogaster along the Sahel/savannahs, Cerastes cerastes and C vipera throughout most desertic...

  2. Strange bedfellows

    DEFF Research Database (Denmark)

    Walther, Olivier; Tisseron, Antonin

    2015-01-01

    Unravelling the Malian puzzle requires looking at the way in which relations between antagonists explain the political violence in Mali. Building on previous work in which we applied social network analysis to West Africa’s conflicts [i], in this research article we will map the alliances and con...... and conflicts between groups involved in the Malian conflict. This map will allow us to formulate some principles to explain the apparent unpredictability of many of the contemporary conflicts in the Sahel-Sahara....

  3. Variability and Predictability of West African Droughts. A Review in the Role of Sea Surface Temperature Anomalies

    Science.gov (United States)

    Rodriguez-Fonseca, Belen; Mohino, Elsa; Mechoso, Carlos R.; Caminade, Cyril; Biasutti, Michela; Gaetani, Marco; Garcia-Serrano, J.; Vizy, Edward K.; Cook, Kerry; Xue, Yongkang; hide

    2015-01-01

    The Sahel experienced a severe drought during the 1970s and 1980s after wet periods in the 1950s and 1960s. Although rainfall partially recovered since the 1990s, the drought had devastating impacts on society. Most studies agree that this dry period resulted primarily from remote effects of sea surface temperature (SST) anomalies amplified by local land surface-atmosphere interactions. This paper reviews advances made during the last decade to better understand the impact of global SST variability on West African rainfall at interannual to decadal time scales. At interannual time scales, a warming of the equatorial Atlantic and Pacific/Indian Oceans results in rainfall reduction over the Sahel, and positive SST anomalies over the Mediterranean Sea tend to be associated with increased rainfall. At decadal time scales, warming over the tropics leads to drought over the Sahel, whereas warming over the North Atlantic promotes increased rainfall. Prediction systems have evolved from seasonal to decadal forecasting. The agreement among future projections has improved from CMIP3 to CMIP5, with a general tendency for slightly wetter conditions over the central part of the Sahel, drier conditions over the western part, and a delay in the monsoon onset. The role of the Indian Ocean, the stationarity of teleconnections, the determination of the leader ocean basin in driving decadal variability, the anthropogenic role, the reduction of the model rainfall spread, and the improvement of some model components are among the most important remaining questions that continue to be the focus of current international projects.

  4. AGRHYMET: A drought monitoring and capacity building center in the West Africa Region

    OpenAIRE

    Seydou B. Traore; Abdou Ali; Seydou H. Tinni; Mamadou Samake; Issa Garba; Issoufou Maigari; Agali Alhassane; Abdallah Samba; Maty Ba Diao; Sanoussi Atta; Pape Oumar Dieye; Hassan B. Nacro; Kouamé G.M. Bouafou

    2014-01-01

    The AGRHYMET Regional Center, a specialized institution of the Permanent Interstates Committee for Drought Control in the Sahel (CILSS), was created in 1974 at the aftermaths of the severe droughts that affected this region in the early 1970s. The mission assigned to the Center was to train personnel, provide adequate equipment for the meteorological and hydrological stations networks, and set up regional and national multidisciplinary working groups to monitor the meteorological, hydrologica...

  5. The Impact of Vulnerability and Resilience to Environmental Changes on Mobility Patterns in West Africa

    OpenAIRE

    Zickgraf, Caroline; Vigil Diaz Telenti, Sara; de Longueville, Florence; Ozer, Pierre; Gemenne, François

    2016-01-01

    From the Sahel to the coast, West Africa is experiencing a variety of climate change impacts, including sea level rise, soil salinization, floods, drought, and desertification, while simultaneously suffering from other forms of environmental degradation. Together, these environmental changes are significantly influencing migration patterns in and out of West Africa. This paper seeks to analyze vulnerability and resilience to environmental changes as they affect and are affected by mobility pa...

  6. : tous les projets | Page 322 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au Sahel, le déficit de la production agricole et pastorale, combiné à la hausse générale des prix des denrées, ont augmenté l'insécurité alimentaire. End Date: 26 juillet 2017. Sujet: DESERTIFICATION. Région: Burkina Faso, Mali. Programme: Agriculture and Food Security. Financement total : CA$ 1,142,600.00.

  7. Vertebrate Damage Control Research in Agriculture, Fiscal Years 1992 and 1993

    Science.gov (United States)

    1993-09-30

    de Aelga. Securite et Autosuffisance Alimentaire Victoire sur les Calamites Naturelles au Sahel. Un Programme de cooperation entre Le Ministere de...Trimestriel. Projet de Recherche sur les Rongeurs au TChad. Projet 698-0517 de Aelga. Securite et Autosuffisance Alimentaire Victoire sur les Calamites...involvement of foreign investigators, results in practical solutions suited to local requirements. In addition , it creates a professional network for

  8. Caractéristiques écologiques du peuplement ligneux de la réserve ...

    African Journals Online (AJOL)

    SARAH

    29 mai 2013 ... Instituto de Ecologia A. C., 401p. Le Houerou HN, 1989. The grazing land ecosystems of the African Sahel. Springer-verlag, Berlin : 282p-. Long G, 1974. Diagnostic phyto-écologique et aménagement du territoire. I. Principes généraux et méthodes. Masson, Paris : 252 p. Mori SA, Boom BM, De Carvalino ...

  9. CTC Sentinel. Volume 4, Issue 2, February 2011

    Science.gov (United States)

    2011-02-01

    the Doctrine of Ibn Tumart,” Studia Islamica 66 (1987): pp. 71-103. fEBRuARy 2011 . VoL 4 . ISSUE 2 “Tourists will stop attending music festivals ...part of their goal of ridding the Sahara and Sahel of foreigners. Tourists will stop attending music festivals , diplomats’ movements will be...profile will be deeper suspicion of the local population, who will be excluded to a greater degree from the economic benefits that industrial

  10. La francophonie menacée? : la percée de l'anglais dans un pays francophone : le cas du Mali

    OpenAIRE

    Nyhus, Marta

    2005-01-01

    THE FRENCH LANGUAGE AT STAKE? The influence of English in a francophone country: the case of Mali. During a period of three years’ stay in Mali, an arid country in the western part of the great African Sahel area, an interesting phenomenon attracted my attention: the extraordinary interest in the English language. Mali is a multi-linguistic country with more than twenty ethnic groups and a corresponding number of local languages. Among these, Bambara is the national lingua franca, while...

  11. Research

    African Journals Online (AJOL)

    abp

    29 oct. 2013 ... en Tunisie entre 1995 et 1997 ont trouvé que le genre féminin était significativement associé à la survenue de faible ... l'insuffisance pondérale à la naissance dans le Sahel tunisien. Santé publique. 2001 ; 13 (4) : 359-366. PubMed ... Démocratique et Populaire. Institut National de santé publique. PubMed ...

  12. Développements hydrauliques et gestion d'un hydrosystème largement anthropisé : le delta du fleuve Sénégal

    OpenAIRE

    Kamara, Saliou

    2013-01-01

    The Senegal delta is between the Sahel, Sahara and the Atlantic Ocean. Its position on the Senegal-Mauritania border, the amount of fresh water available throughout the year and the importance of its agricultural potential irrigable areas and have made this a vital wetland area (agriculture, livestock, tourism, fishing, etc.). However, if different from the colonization rural development programs have been implemented, it must be admitted that the failures were also numerous.The construction ...

  13. effet d'une complementation energetique en periode humide

    African Journals Online (AJOL)

    AISA

    I. B. GNANDA1, A. J. NIANOGO2, J. S. ZOUNDI1, B. FAYE3 et O. ZONO1. 1Institut de l'Environnement et de ... Du point de vue composition chimique de lait, les meilleures valeurs ont été également enregistrées avec les chèvres du lot 2. ... Sahel en vue d'une meilleure production laitière. MATERIEL ET METHODES.

  14. International Journal of Biological and Chemical Sciences - Vol 8 ...

    African Journals Online (AJOL)

    Seed (Nutmeg) on Helicobacter pylori induced gastritis in albino rats: in vitro and in vivo studies · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT .... Effet de la combinaison des fumures organo-minérales et de la rotation niébé-mil sur la nutrition azotée et les rendements du mil au sahel · EMAIL FREE FULL TEXT ...

  15. A mechanism for long-term changes of Atlantic tropical cyclone intensity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Liguang; Tao, Li [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing, Jiangsu (China)

    2011-05-15

    Although previous studies reported upward trends in the basin-wide average lifetime, annual frequency, proportion of intense hurricanes and annual accumulated power dissipation index of Atlantic tropical cyclones (TCs) over the past 30 years, the basin-wide intensity did not increase significantly with the rising sea surface temperature (SST). Observational analysis and numerical simulation conducted in this study suggest that Sahel rainfall is the key to understanding of the long-term change of Atlantic TC intensity. The long-term changes of the basin-wide TC intensity are generally associated with variations in Sahara air layer (SAL) activity and vertical wind shear in the main development region (MDR), both of which are highly correlated with Sahel rainfall. The drying Sahel corresponds to an equatorward shift in the African easterly jet and African easterly wave activity, introducing the SAL to lower latitudes and increasing the MDR vertical wind shear. As a result, Atlantic TCs are more vulnerable to the suppressing effects of the SAL and vertical wind shear. Since the SST warming, especially in the tropical Indian Ocean, is a dominant factor for the Sahel drying that occurred over the past 30 years, it is suggested that the remote effect of SST warming is important for the long-term change of Atlantic TC intensity. Although influence of the AMO warm phase that started in the early 1990s alone can provide a favorable condition for TC intensification, its influence may have been offset by the influence of the ongoing SST warming, particularly in the Indian Ocean. As a result, there was no significant trend observed in the basin-wide average and peak intensity of Atlantic TCs. (orig.)

  16. West African monsoon dynamics and precipitation: the competition between global SST warming and CO2 increase in CMIP5 idealized simulations

    Science.gov (United States)

    Gaetani, Marco; Flamant, Cyrille; Bastin, Sophie; Janicot, Serge; Lavaysse, Christophe; Hourdin, Frederic; Braconnot, Pascale; Bony, Sandrine

    2017-02-01

    Climate variability associated with the West African monsoon (WAM) has important environmental and socio-economic impacts in the region. However, state-of-the-art climate models still struggle in producing reliable climate predictions. An important cause of this low predictive skill is the sensitivity of climate models to different forcings. In this study, the mechanisms linking the WAM dynamics to the CO2 forcing are investigated, by comparing the effect of the CO2 direct radiative effect with its indirect effect mediated by the global sea surface warming. The July-to-September WAM variability is studied in climate simulations extracted from the Coupled Model Intercomparison Project Phase 5 archive, driven by prescribed sea surface temperature (SST). The individual roles of global SST warming and CO2 atmospheric concentration increase are investigated through idealized experiments simulating a 4 K warmer SST and a quadrupled CO2 concentration, respectively. Results show opposite and competing responses in the WAM dynamics and precipitation. A dry response (-0.6 mm/day) to the SST warming is simulated in the Sahel, with dryer conditions over western Sahel (-0.8 mm/day). Conversely, the CO2 increase produces wet conditions (+0.5 mm/day) in the Sahel, with the strongest response over central-eastern Sahel (+0.7 mm/day). The associated responses in the atmospheric dynamics are also analysed, showing that the SST warming affects the Sahelian precipitation through modifications in the global tropical atmospheric dynamics, reducing the importance of the regional drivers, while the CO2 increase reinforces the coupling between precipitation and regional dynamics. A general agreement in model responses demonstrates the robustness of the identified mechanisms linking the WAM dynamics to the CO2 direct and indirect forcing, and indicates that these primary mechanisms are captured by climate models. Results also suggest that the spread in future projections may be caused by

  17. Confronting Africa’s Sobels

    Science.gov (United States)

    2013-01-01

    Nigeriens Movement for Justice or MNJ), a mostly Tuareg-based group in northern Niger fighting for greater revenue sharing from uranium mining...recent history of the Tuareg, a traditionally nomadic people who live in the Sahara and northern Sahel of Mali and Niger . There have been several...claimed an entire special forces unit, the Niger Rapid Intervention Company, which had been trained by the American military, defected in 2007. The

  18. The African Standby Force: A Premature Enterprise Dictated by Circumstances?

    Science.gov (United States)

    2011-03-23

    particularly active in Somalia and the Sahel region. 5 Further, workers of AREVA, a French firm exploiting uranium mines in Niger have been kidnapped...by AQIM terrorists, collaborating with Touareg rebels groups in northern Mali and Niger while oil installations in the Gulf of Guinea have been...subjected to attacks from the rebel group, the Movement for the Emancipation of the Niger Delta (MEND). Future Security Environment. Security challenges

  19. Local Landscapes and Constructions of World Space: Medieval  Inscriptions, Cognitive Dissonance, and the Course of the Niger

    OpenAIRE

    Moraes Farias, Paulo Fernando de

    2011-01-01

    In the West African Sahel, Islam induced processes of cognitive change as spaces and history were given new meaning over time. In the expanding Muslim universe, they were reconstructed with reference to the core regions of the Islamic world and the founding events of Islam. This brought issues of cognitive dissonance to the interpretation of the past, when people were simultaneously confronted with different and incompatible heuristic heritages. This paper investigates such changes in the rep...

  20. Research on food security makes a difference for African women ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    17 avr. 2014 ... Le microdosage des engrais, une innovation qui profite aux femmes du Sahel. Grâce à l'application localisée de petites quantités d'engrais (ou microdosage), alliée à l'amélioration des trous d'ensemencement afin de recueill. Voir davantageLe microdosage des engrais, une innovation qui profite aux ...

  1. Réduire la pauvreté dans les montagnes de l'Atlas | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    20 avr. 2016 ... Le microdosage des engrais, une innovation qui profite aux femmes du Sahel. Grâce à l'application localisée de petites quantités d'engrais (ou microdosage), alliée à l'amélioration des trous d'ensemencement afin de recueill. Voir davantageLe microdosage des engrais, une innovation qui profite aux ...

  2. Les Nigérianes améliorent leur sort grâce aux légumes indigènes ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    28 févr. 2014 ... Le microdosage des engrais, une innovation qui profite aux femmes du Sahel. Grâce à l'application localisée de petites quantités d'engrais (ou microdosage), alliée à l'amélioration des trous d'ensemencement afin de recueill. Voir davantageLe microdosage des engrais, une innovation qui profite aux ...

  3. Gestion des ressources naturelles pour une sécurité alimentaire ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au Sahel, le déficit de la production agricole et pastorale, combiné à la hausse générale des prix des denrées, ont augmenté l'insécurité alimentaire. Pour garantir leur sécurité alimentaire, les populations rurales utilisent des techniques de production agricole visant à maximiser leur production sans nécessairement se ...

  4. Frequency of extreme Sahelian storms tripled since 1982 in satellite observations.

    Science.gov (United States)

    Taylor, Christopher M; Belušić, Danijel; Guichard, Françoise; Parker, Douglas J; Vischel, Théo; Bock, Olivier; Harris, Phil P; Janicot, Serge; Klein, Cornelia; Panthou, Gérémy

    2017-04-26

    The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense storms-mesoscale convective systems (MCSs)-poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in 'extreme' daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and

  5. A new perspective on West African hydroclimate during the last deglaciation

    Science.gov (United States)

    Parker, Andrew O.; Schmidt, Matthew W.; Jobe, Zane R.; Slowey, Niall C.

    2016-09-01

    Widespread drought characterized the Heinrich 1 and Younger Dryas cold periods of the last deglaciation throughout much of Africa, causing large increases in dust emissions from the Sahara and Sahel. At the same time, increases in wind strength may have also contributed to dust flux, making it difficult to interpret dust records alone as reflecting changes in rainfall over the region. The Niger River has the third largest drainage basin in Africa and drains most of the Sahara and Sahel and thus preserves and propagates climatic signals. Here, we present new reconstructions of Niger Delta sea surface salinity and Niger River discharge for the last 20,000 years in order to more accurately reconstruct the onset of the Western African Monsoon system. Based on calculated δ18OSEAWATER (δ18OSW) and measured Ba/Ca ratios in planktonic foraminifera, these new records reflect changes in sub-Saharan precipitation across the Niger River Basin in West Africa and reveal that the West African Monsoon system began to intensify several thousand years after the equatorial Monsoon system in Central Africa. We also present new records of primary productivity in the Niger Delta that are related to wind-driven upwelling and show that productivity is decoupled from changes in Niger River discharge. Our results suggest that wind strength, rather than changes in monsoon moisture, was the primary driver of dust emissions from the Sahara and Sahel across the last deglaciation.

  6. [Demography of the young, demography of disarray].

    Science.gov (United States)

    Mbacke, C; Ouedraogo, D

    1994-12-01

    The population of the Sahel is one of the youngest in the world, with 47% under age 15. The extreme youth and high fertility of these countries will result in rapid growth for at least the next three decades. Significant aging remains a distant prospect. For the Sahel societies, the world's poorest, children were traditionally a source of respect, relative security, and support in old age. Reaching old age without the support of children remains a difficult fate. Maximizing the number of children is still the best way for the poor to improve the chance of having at least one economically successful child. The rule of solidarity still requires social redistribution of acquired individual wealth. Recent socioeconomic changes and family planning campaigns will eventually modify pronatalist beliefs and practices, especially in urban areas. Economic development, which has historically been one of the factors most closely linked to enduring fertility decline, is proceeding slowly. The population of the Sahel will surely more than double by the year 2020, from 40 million in 1988 to nearly 100 million. Demand for health care, education, employment, and services of all kinds will consequently grow. Economic and demographic growth and the urban explosion of the past half century have greatly loosened the control of traditional authorities and values over the young. But poverty and underdevelopment limit their access to new ways of life and especially to western modes of consumption. The urban informal sector permits daily survival even as rural life is losing its little remaining dynamism and ability to absorb the young. The problems confronting young people have demonstrated to them that they must rely on their own efforts and expect little from the government. Their challenges are political as well as economic and cultural, as the governments created at independence lose the capacity to control everyday life.

  7. Internal diversification of non-Sub-Saharan haplogroups in Sahelian populations and the spread of pastoralism beyond the Sahara.

    Science.gov (United States)

    Kulichová, Iva; Fernandes, Verónica; Deme, Alioune; Nováčková, Jana; Stenzl, Vlastimil; Novelletto, Andrea; Pereira, Luísa; Černý, Viktor

    2017-10-01

    Today, African pastoralists are found mainly in the Sahel/Savannah belt spanning 6,000 km from west to east, flanked by the Sahara to the north and tropical rainforests to the south. The most significant group among them are the Fulani who not only keep cattle breeds of possible West Eurasian ancestry, but form themselves a gene pool containing some paternally and maternally-transmitted West Eurasian haplogroups. We generated complete sequences for 33 mitogenomes belonging to haplogroups H1 and U5 (23 and 10, respectively), and genotyped 16 STRs in 65 Y chromosomes belonging to haplogroup R1b-V88. We show that age estimates of the maternal lineage H1cb1, occurring almost exclusively in the Fulani, point to the time when the first cattle herders settled the Sahel/Savannah belt. Similar age estimates were obtained for paternal lineage R1b-V88, which occurs today in the Fulani but also in other, mostly pastoral populations. Maternal clade U5b1b1b, reported earlier in the Berbers, shows a shallower age, suggesting another possibly independent input into the Sahelian pastoralist gene pool. Despite the fact that animal domestication originated in the Near East ∼ 10 ka, and that it was from there that animals such as sheep, goats as well as cattle were introduced into Northeast Africa soon thereafter, contemporary cattle keepers in the Sahel/Savannah belt show uniparental genetic affinities that suggest the possibility of an ancient contact with an additional ancestral population of western Mediterranean ancestry. © 2017 Wiley Periodicals, Inc.

  8. Simulation of Rainfall Variability Over West Africa

    Science.gov (United States)

    Bader, J.; Latif, M.

    The impact of sea surface temperature (SST) and vegetation on precipitation over West Africa is investigated with the atmospheric general circulation model ECHAM4.x/T42. Ensemble experiments -driven with observed SST- show that At- lantic SST has a significant influence on JJA precipitation over West Africa. Four- teen experiments were performed in which the climatological SST was enhanced or decreased by one Kelvin in certain ocean areas. Changing SST in the eastern tropi- cal Atlantic only caused significant changes along the Guinea Coast, with a positive SSTA increasing rainfall and a negative reducing it. The response was nearly linear. Changing SST in other ocean areas caused significant changes over West Africa, es- pecially in the Sahel area. The response is found to be non linear, with only negative SSTA leading to significant reduction in Sahel rainfall. Also, the impact of the SSTAs from the different ocean regions was not additive with respect to the rainfall. Four simulations with a coupled model (the simple dynamic vegetation model (SVege) and the ECHAM4-AGCM were coupled) were also performed, driven with observed SST from 1945 to 1998. The standard ECHAM-AGCM -forced by the same observed SST- was able to reproduce the drying trend from the fifties to the mid-eighties in the Sahel, but failed to mirror the magnitude of the rainfall anomalies. The coupled model was not only able to reproduce this drying trend, but was also able to better reproduce the amplitudes of the rainfall anomalies. The dynamic vegetation acted like an amplifier, increasing the SST induced rainfall anomalies.

  9. Africa's Great Green Wall Initiative: a model for restoration success

    Science.gov (United States)

    Berrahmouni, Nora; Sacande, Moctar

    2014-05-01

    The Great Green Wall for the Sahara and the Sahel Initiative was launched to address the increasing challenges of land degradation, desertification and drought, climate change, food insecurity and poverty in more than 20 countries. Restoration of agro-sylvo-pastoral landscapes and degraded lands is one of the priority interventions initiated, enabling the springing up of green nests of life. When complete, the Great Green Wall of Africa will reverse the seemingly unstoppable desertification and address the development of its drylands' inhabitant rural communities. Today's planting of modest seedlings will grow into vast mosaics of forest and agroforestry landscapes and grasslands, which will provide essential ecosystem goods and services, restore lost livelihoods and create new wealth. The ambition of reforestation efforts within this initiative - the like of which the world has never seen before - sounds like an impossible dream. However, learning from past mistakes and capitalising on current advancement in science and technology, it is a reality that is taking root. Following a successful restoration model that RBG Kew experts have devised, we are helping to mobilise, train and support communities in four border regions in Burkina Faso, Mali and Niger. In collaboration with FAO, the Millennium Seed Bank Partnership is using its unique expertise to ensure that seeds of environmentally well-adapted and economically useful local species are collected and planted in communal gardens and village agroforestry systems managed by the communities themselves. In our first year, an estimated total of 162,000 seedlings and 61 kg of seeds from 40 useful native species, including grasses for livestock, have been planted to cover 237 ha of farmer-managed land in 19 villages. The keen interest it has created has indicated that these figures will rise five-fold in the second year. These green bricks are the foundations of the living wall that will eventually reach across the

  10. Climate dynamics: a network-based approach for the analysis of global precipitation.

    Directory of Open Access Journals (Sweden)

    Stefania Scarsoglio

    Full Text Available Precipitation is one of the most important meteorological variables for defining the climate dynamics, but the spatial patterns of precipitation have not been fully investigated yet. The complex network theory, which provides a robust tool to investigate the statistical interdependence of many interacting elements, is used here to analyze the spatial dynamics of annual precipitation over seventy years (1941-2010. The precipitation network is built associating a node to a geographical region, which has a temporal distribution of precipitation, and identifying possible links among nodes through the correlation function. The precipitation network reveals significant spatial variability with barely connected regions, as Eastern China and Japan, and highly connected regions, such as the African Sahel, Eastern Australia and, to a lesser extent, Northern Europe. Sahel and Eastern Australia are remarkably dry regions, where low amounts of rainfall are uniformly distributed on continental scales and small-scale extreme events are rare. As a consequence, the precipitation gradient is low, making these regions well connected on a large spatial scale. On the contrary, the Asiatic South-East is often reached by extreme events such as monsoons, tropical cyclones and heat waves, which can all contribute to reduce the correlation to the short-range scale only. Some patterns emerging between mid-latitude and tropical regions suggest a possible impact of the propagation of planetary waves on precipitation at a global scale. Other links can be qualitatively associated to the atmospheric and oceanic circulation. To analyze the sensitivity of the network to the physical closeness of the nodes, short-term connections are broken. The African Sahel, Eastern Australia and Northern Europe regions again appear as the supernodes of the network, confirming furthermore their long-range connection structure. Almost all North-American and Asian nodes vanish, revealing that

  11. Interactions of atmospheric gases and aerosols with the monsoon dynamics over the Sudano-Guinean region during AMMA

    Directory of Open Access Journals (Sweden)

    A. Deroubaix

    2018-01-01

    Full Text Available Carbon monoxide, CO, and fine atmospheric particulate matter, PM2.5, are analyzed over the Guinean Gulf coastal region using the WRF-CHIMERE modeling system and observations during the beginning of the monsoon 2006 (from May to July, corresponding to the Africa Multidisciplinary Monsoon Analysis (AMMA campaign period. Along the Guinean Gulf coast, the contribution of long-range pollution transport to CO or PM2.5 concentrations is important. The contribution of desert dust PM2.5 concentration decreases from  ∼ 38 % in May to  ∼ 5 % in July. The contribution of biomass burning PM2.5 concentration from Central Africa increases from  ∼ 10 % in May to  ∼ 52 % in July. The anthropogenic contribution is  ∼ 30 % for CO and  ∼ 10 % for PM2.5 during the whole period. When focusing only on anthropogenic pollution, frequent northward transport events from the coast to the Sahel are associated with periods of low wind and no precipitation. In June, anthropogenic PM2.5 and CO concentrations are higher than in May or July over the Guinean coastal region. Air mass dynamics concentrate pollutants emitted in the Sahel due to a meridional atmospheric cell. Moreover, a part of the pollution emitted remotely at the coast is transported and accumulated over the Sahel. Focusing the analysis on the period 8–15 June, anthropogenic pollutants emitted along the coastline are exported toward the north especially at the beginning of the night (18:00 to 00:00 UTC with the establishment of the nocturnal low level jet. Plumes originating from different cities are mixed for some hours at the coast, leading to high pollution concentration, because of specific disturbed meteorological conditions.

  12. Impact of climate change on mid-twenty-first century growing seasons in Africa

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Kerry H.; Vizy, Edward K. [The University of Texas at Austin, Department of Geological Sciences, Jackson School of Geosciences, Austin, TX (United States)

    2012-12-15

    Changes in growing seasons for 2041-2060 across Africa are projected using a regional climate model at 90-km resolution, and confidence in the predictions is evaluated. The response is highly regional over West Africa, with decreases in growing season days up to 20% in the western Guinean coast and some regions to the east experiencing 5-10% increases. A longer growing season up to 30% in the central and eastern Sahel is predicted, with shorter seasons in parts of the western Sahel. In East Africa, the short rains (boreal fall) growing season is extended as the Indian Ocean warms, but anomalous mid-tropospheric moisture divergence and a northward shift of Sahel rainfall severely curtails the long rains (boreal spring) season. Enhanced rainfall in January and February increases the growing season in the Congo basin by 5-15% in association with enhanced southwesterly moisture transport from the tropical Atlantic. In Angola and the southern Congo basin, 40-80% reductions in austral spring growing season days are associated with reduced precipitation and increased evapotranspiration. Large simulated reductions in growing season over southeastern Africa are judged to be inaccurate because they occur due to a reduction in rainfall in winter which is over-produced in the model. Only small decreases in the actual growing season are simulated when evapotranspiration increases in the warmer climate. The continent-wide changes in growing season are primarily the result of increased evapotranspiration over the warmed land, changes in the intensity and seasonal cycle of the thermal low, and warming of the Indian Ocean. (orig.)

  13. Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara

    Science.gov (United States)

    Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas

    2017-09-01

    Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR's CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

  14. Multimodel precipitation responses to removal of U.S. sulfur dioxide emissions

    Science.gov (United States)

    Westervelt, D. M.; Conley, A. J.; Fiore, A. M.; Lamarque, J.-F.; Shindell, D.; Previdi, M.; Faluvegi, G.; Correa, G.; Horowitz, L. W.

    2017-05-01

    Emissions of aerosols and their precursors are declining due to policies enacted to protect human health, yet we currently lack a full understanding of the magnitude, spatiotemporal pattern, statistical significance, and physical mechanisms of precipitation responses to aerosol reductions. We quantify the global and regional precipitation responses to U.S. SO2 emission reductions using three fully coupled chemistry-climate models: Community Earth System Model version 1, Geophysical Fluid Dynamics Laboratory Coupled Model 3, and Goddard Institute for Space Studies ModelE2. We contrast 200 year (or longer) simulations in which anthropogenic U.S. sulfur dioxide (SO2) emissions are set to zero with present-day control simulations to assess the aerosol, cloud, and precipitation response to U.S. SO2 reductions. In all three models, reductions in aerosol optical depth up to 70% and cloud droplet number column concentration up to 60% occur over the eastern U.S. and extend over the Atlantic Ocean. Precipitation responses occur both locally and remotely, with the models consistently showing an increase in most regions considered. We find a northward shift of the tropical rain belt location of up to 0.35° latitude especially near the Sahel, where the rainy season length and intensity are significantly enhanced in two of the three models. This enhancement is the result of greater warming in the Northern versus Southern Hemispheres, which acts to shift the Intertropical Convergence Zone northward, delivering additional wet season rainfall to the Sahel. Two of our three models thus imply a previously unconsidered benefit of continued U.S. SO2 reductions for Sahel precipitation.

  15. Cotton seed borne disease in Golestan Province in Northern Iran

    OpenAIRE

    ARABSALMANİ, M.

    2015-01-01

    Abstract. In order to effect of seed mycroflora to incidence of seedling diseases and verticillium wilt, five thousands of cotton seed were collected from five categories (nucleus, super elite, elite, maternal and certified seed) of Sahel cultivar. Seed were delinted with sulfuric acid and treated by sodium hypochlorite 0.5%.Coat and embryo of seeds separated and placed on Potato Dexterous Agar and Alcol Agar medium and incubated at 18 – 240c. After 5 – 15 days fungi that grew on were isolate...

  16. Measurements of Aerosol Hygroscopic Growth From Eight Different Regions and Aerosol Types

    Science.gov (United States)

    Jefferson, A.; Ogren, J.

    2007-12-01

    The change in the aerosol scattering coefficient with relative humidity has been measured at eight regions across the Earth over a time period of a few months to eight years. The measurement sites include the Arctic, Northeastern North America, Central US, Northwestern US, the Korean Peninsula, Indian Ocean, African Sahel and Central Europe. The aerosol types in these studies include mixtures of dust, smoke, pollution and marine aerosol. The covariance in the aerosol hygroscopic growth factor with other aerosol properties and source regions will be discussed as well as implications for direct and indirect radiative forcing.

  17. Coastal uplift west of Algiers (Algeria): pre- and post-Messinian sequences of marine terraces and rasas and their associated drainage pattern

    Science.gov (United States)

    Authemayou, Christine; Pedoja, Kevin; Heddar, Aicha; Molliex, Stéphane; Boudiaf, Azzedine; Ghaleb, Bassam; Van Vliet Lanoe, Brigitte; Delcaillau, Bernard; Djellit, Hamou; Yelles, Karim; Nexer, Maelle

    2017-01-01

    The North Africa passive margin is affected by the ongoing convergence between the African and Eurasian plates. This convergence is responsible for coastal uplift, folding, and reverse faulting on new and reactivated faults on the margin. The active deformation is diffuse and thus rather difficult to locate precisely. We aim to determine how a coastal landscape evolve in this geodynamic setting and gain insights into active tectonics. More particularly, we evidence and quantify coastal uplift pattern of the Chenoua, Sahel, and Algiers reliefs (Algeria), using sequences of marine terraces and rasas and computing several morphometric indices from the drainage pattern. Upper and Middle Pleistocene uplift rates are obtained by fossil shoreline mapping and preliminary U/Th dating of associated coastal deposits. Extrapolation of these rates combined to analyses of sea-level referential data and spatial relationships between marine terraces/rasas and other geological markers lead us to tentatively propose an age for the highest coastal indicators (purported the oldest). Values of morphometric indices showing correlations with uplift rate allow us to analyze uplift variation on area devoid of coastal sequence. Geological and geomorphological data suggest that coastal uplift probably occurred since the Middle Miocene. It resulted in the emergence of the Algiers massif, followed by the Sahel ridge massif. The Sahel ridge has asymmetrically grown by folding from west to east and was affected by temporal variation of uplift. Compared to previous study, the location of the Sahel fold axis has been shifted offshore, near the coast. The Chenoua fault vertical motion does not offset significantly the coastal sequence. Mean apparent uplift rates and corrected uplift rates since 120 ka are globally steady all along the coast with a mean value of 0.055 ± 0.015 mm/year (apparent) and of 0.005 ± 0.045 mm/year (corrected for eustasy). Mean apparent coastal uplift rates between 120 and

  18. Identification of aerosol particle sources in semi-rural area of Kwabenya, near Accra, Ghana, by EDXRF techniques

    DEFF Research Database (Denmark)

    Aboh, Innocent Joy Kwame; Henrikson, Dag; Laursen, Jens

    2009-01-01

    Small aerosol particles have for a long time been known to be harmful to humans, and are today regarded to cause a larger number of deaths than traffic accidents globally. Energy dispersive x-ray fluorescence (EDXRF) is awell known method that has been used for identification of toxic as well...... is frequently exposed to Harmattan dust from the Sahara-Sahel region. In total 171 filters each of PM2.5 and PM(2.5-10) were collected during 1 year. Levels of elements, black carbon (BC) and mass, were determined for both particle sizes. Principal component analysis (PCA) was performed on the datasets from...

  19. Bioengineered yogurt: ‘open source’ medicine

    Directory of Open Access Journals (Sweden)

    Shireesh Apte

    2012-12-01

    Full Text Available The ease with which commensal bacteria in yogurt can be bioengineered to express an array of biotherapeutics, coupled with altruistic distribution systems that can easily include those, most likely to benefit (think expression of antiplasmodial peptides in the Bifidobacterium genus so that a herder in the Sahel can inoculate this yogurt culture into goat milk thus making ‘antimalarial yogurt’ for free for his entire village. This could potentially go on as long as the plasmid is stable and could lead to a revolution in the way medicines could become ‘open sourced’.

  20. : Couscous Sahelian style (Senegal, Mali, Mauritania)

    OpenAIRE

    Chastanet, Monique

    2010-01-01

    We too often forget that couscous has been consumed in the western Sahel for several centuries for everyday meals or celebrations, as a snack or during trips. The diversity of its names in Senegambia and neighbouring regions from the coast to the Niger Bend clearly reflects that it has a long history, even though its origins are controversial and hard to elucidate. The first evidence of couscous south of the Sahara comes from Ibn Battûta in the mid-14th century and two Portuguese texts from t...

  1. Direct Radiative Effect of Mineral Dust on the Middle East and North Africa Climate

    KAUST Repository

    Bangalath, Hamza Kunhu

    2016-11-01

    strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. Importantly, the summer precipitation over the semi-arid strip south of Sahara, including Sahel, increases in response to dust radiative effect. The maximum response and sensitivity are predicted over this region. The sensitivity of the responses over Sahel, especially that of precipitation, is comparable to the mean state. Locally, the precipitation increase reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. As the region is characterized by the "Sahel drought", the predicted precipitation sensitivity to the dust loading over this region has a wide-range of socioeconomic implications. The present study, therefore, suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the MENA climate in general, and of Sahel in particular.

  2. Demand for Contraception in Sahelian Countries: Are Men's and Women's Expectations Converging?. Burkina Faso and Mali, Compared to Ghana

    OpenAIRE

    Armelle Andro; Véronique Hertrich

    2002-01-01

    The low level of contraceptive practice in the Sahel countries is often attributed to the deficiencies of family planning services. It is assumed, on the basis of surveys among women, that a demand for contraception exists. This article re-examines the issue of demand for contraception, looking not just at the expectations of women, but also of men and of couples. The analyses are based on the Demographic and Health Surveys carried out in Burkina Faso (1993) and Mali (1995-1996), with Ghana (...

  3. Accès à l'eau pour les agricultrices sahéliennes : enjeux pour une ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    6 mars 2014 ... Cet ouvrage collectif se penche sur l'origine, les manifestations et les conséquences des clivages de genre dans l'accès à l'eau et l'exploitation et le contrôle de l'eau au Sahel. Il découle d'un projet appuyé par le CRDI et mené par le Réseau africain pour le développement intégré (RADI) qui examinait les ...

  4. Towards understanding the genetics of tolerance to low soil phosphorus conditions in West African pearl millet

    OpenAIRE

    Gemenet, Dorcus Chepkesis

    2015-01-01

    About two hundred and twenty three million people are undernourished in Sub-Saharan Africa (SSA) with 11 million people being food insecure in the Sahel region of West Africa (WA). A growing global population and climate change are expected to exacerbate this situation and present new challenges on global food production. Phosphate rock, a non-renewable resource is expected to be depleted in about 40-400 years depending on the source of information but a phosphorus (P) peak (where P demand ex...

  5. Does EO NDVI seasonal metrics capture variations in species composition and biomass due to grazing in semi-arid grassland savannas?

    DEFF Research Database (Denmark)

    Olsen, J. L.; Miehe, S.; Ceccato, Pietro

    2015-01-01

    vegetation index (NDVI) data a greening of the Sahel since the 1980s has been identified. However, it is poorly understood how commonly applied remote sensing techniques reflect the influence of extensive grazing (and changes in grazing pressure) on natural rangeland vegetation. This paper analyses the time...... exclosures as compared to grazed areas, substantially exceeding the amount of biomass expected to be ingested by livestock for this area. The seasonal integrated NDVI (NDVI small integral; capturing only the signal inherent to the growing season recurrent vegetation), derived using absolute thresholds...

  6. Características de los paseriformes europeos que invernan en el Parque Nacional de las Aves del Djoudj (África occidental)

    OpenAIRE

    Juan Arizaga, Daniel Alonso, Ivan Maggini, Luis Romero, Antonio Vilches, Gorka Belamendia

    2011-01-01

    El Sahel es una de las regiones más importantes para las especies de paseriformes europeos que invernan en África subsahariana. En el invierno de 2010 (diciembre) se desarrolló una expedición al Parque Nacional de las Aves del Djoudj (Senegal), en África occidental. Durante la expedición se capturaron varias especies de paseriformes europeos, en ocho de las cuales las capturas fueron superiores a 5 ejemplares: Acrocephalus schoenobaenus (L., 1758), A. scirpaceus Herman, 1804, Luscinia svecica...

  7. Phytochemical study of prickly pear from southern Morocco

    Directory of Open Access Journals (Sweden)

    Z. Bouzoubaâ

    2016-06-01

    Full Text Available This work concerns the phytochemical study of the prickly pear pulp’s fruits of two opuntia cultivars; Achefri and Amouslem widely present in two regions of southern Morocco; Arbaa Sahel and Asgherkis that are different in their altitude and annual rainfall. The results of the phytochemical study show that the levels of antioxidants have a non-significant difference between the fruits of the two sites (comparing Amouslem and Achefri in the same site, on the one hand, for the differences due to the variety or cultivar, on the other hand between Amouslem and Achefri from the two sites to show the site effect.

  8. Sahelian rangeland response to changes in rainfall over two decades in the Gourma region, Mali

    Science.gov (United States)

    Hiernaux, Pierre; Mougin, Eric; Diarra, Lassine; Soumaguel, Nogmana; Lavenu, François; Tracol, Yann; Diawara, Mamadou

    2009-08-01

    SummaryTwenty-five rangeland sites were monitored over two decades (1984-2006) first to assess the impact of the 1983-1984 droughts on fodder resources, then to better understand ecosystem functioning and dynamics. Sites are sampled along the south-north bioclimatic gradient in Gourma (Mali), within three main edaphic situations: sandy, loamy-clay and shallow soils. In addition, three levels of grazing pressure where systematically sampled within sandy soils. Located at the northern edge of the area reached by the West African monsoon, the Gourma gradient has recorded extremes in inter-annual variations of rainfall and resulting variations in vegetation growth. Following rainfall variability, inter-annual variability of herbaceous yield increases as climate gets dryer with latitudes at least on the sandy soils sites. Local redistribution of rainfall explains the high patchiness of herbaceous vegetation, especially on shallow soils. Yet spatial heterogeneity of the vegetation does not buffer between year yield variability that increases with spatial heterogeneity. At short term, livestock grazing during the wet season affects plant growth and thus yield in direction and proportions that vary with the timing and intensity of grazing. In the longer term, grazing also impinges upon species composition in many ways. Hence, long histories of heavy grazing promote either long cycle annuals refused by livestock or else short cycle good quality feed species. Primary production is maintained or even increased in the case of refusal such as Sida cordifolia, and is lessened in the case of short cycle species such as Zornia glochidiata. These behaviours explain that the yield anomalies calculated for the rangelands on sandy soils relative to the yield of site less grazed under similar climate tend to be negative in northern Sahel where the scenario of short cycle species dominates, while yield anomalies are close to nil in centre Sahel and slightly positive in South Sahel where

  9. Statut hydrique de quatre espèces ligneuses soudaniennes dans la forêt de Nazinon, Burkina Faso

    OpenAIRE

    Bationo, B.A.; Ouedraogo, S.J.; Alexandre, Daniel-Yves; Guinko, S.

    2001-01-01

    L'adéquation entre les ligneux et les conditions hydriques des sites est un des facteurs déterminants de la réussite des reboisements et de la production forestière au Sahel. C'est pour contribuer à une meilleure connaissance du fonctionnement hydrique des espèces forestières que les courbes volume-pression, la dynamique journalière et saisonnière du potentiel hydrique foliaire et la morphologie racinaire de #Isoberlinia doka$ Caib. et Stapf., #Detarium microcarpum$ Guill. et Perr., #Piliosti...

  10. Effet d\\'une complémentation énergétique en période humide sur la ...

    African Journals Online (AJOL)

    L\\'étude vise à évaluer le besoin de la chèvre laitière du Sahel en complément énergétique en période pluvieuse. Vingt sept chèvres laitières, réparties de façon aléatoire en trois lots suivant leur âge (1 à 10 ans) et leur rang de lactation (1 à 6) ont été utilisés pour l\\'essai. Le premier lot (lot 1) d\\'animaux ont servi de témoin ...

  11. Prospects for agroforestry in REDD+ landscapes in Africa

    DEFF Research Database (Denmark)

    Minang, Peter A.; Duguma, Lalisa A.; Bernard, Florence

    2014-01-01

    to pastoralists, agro-pastoralists and forest-users, all depend on the availability of vegetation resources and are affected by fluctuations in the available vegetation resource. Vegetation dynamics are controlled by both natural and human factors, including climate change and variability, increased concentration......Vegetation dynamics of the West African Sahel has attracted great scientific interest over the last 40 years because of the dramatic inter-decadal variability observed in the resource base of the region directly impacting on the livelihoods of the West African population. From farmers...

  12. Genetic variability in the compatibility between Schistosoma haematobium and its potential vectors in Niger. Epidemiological implications.

    Science.gov (United States)

    Véra, C; Jourdane, J; Sellin, B; Combes, C

    1990-06-01

    A populational study of the compatibility between Schistosoma haematobium and its potential vectors has been carried out in the Niger, confronting samples of S. haematobium populations from three epidemiologic foci with Bulinus populations originating from the same focus (sympatric infection) and with Bulinus populations from other foci (allopatric infections). The three transmission foci selected were irrigation canals in ricefields along the Niger river where one finds: Bulinus truncatus rohlfsi, Bulinus globosus, Bulinus forskalii and Bulinus senegalensis; temporary pools in the Sahel area where one finds B. truncatus and B. senegalensis; permanent pools of the "guelta" type in Sahara area where only B. truncatus occurs. As a compatibility test, the snail infection test was selected, with particular emphasis on optimising its reliability. Snail-infection experiments showed that B. truncatus and B. senegalensis are very good potential vectors, with infection rates ranging between 71.5 and 85.9%. B. globosus and B. forskalii, on the other hand, are totally incompatible. The mean infection percentages in the sympatric and allopatric combinations carried out with the S. haematobium-B. truncatus couple were very similar. This character strongly suggests a lack of isolation in schistosome populations and a circulation of the parasite genome through the mobility of infected human populations (Peuls and Touaregs) in Sahel zone. This study, in relation with snail surveys carried out in parallel, shows that the main types of aquatic environments on the Niger act as high risk areas for schistosome transmission.

  13. Evaluation of Wind Energy Potential as a Power Generation Source in Chad

    Directory of Open Access Journals (Sweden)

    Djamal Hissein Didane

    2017-01-01

    Full Text Available Long-term wind speed data for thirteen meteorological stations, measured over a five-year period, were statistically analyzed using the two-parameter Weibull distribution function. The purpose of this study is to reveal for the first time the wind power potentials in Chad and to provide a comprehensive wind map of the country. The results show that the values of the shape and scale parameters varied over a wide range. Analysis of the seasonal variations showed that higher wind speed values occur when the weather condition is generally dry and they drop considerably when the weather condition is wet. It was also observed that the wind speed increases as one moves from the southern zone to the Saharan zone. Although the wind power at each site varies significantly, however, the potentials of most of the sites were encouraging. Nevertheless, according to the PNNL classification system, they are favorable for small-scale applications only. A few stations in the middle of Sudanian and Sahel regions are found to be not feasible for wind energy generation due to their poor mean wind speed. The prevailing wind direction for both Saharan and Sahel regions is dominated by northeastern wind, while it diverged to different directions in the Sudanian zone.

  14. Regional Climate Variability Under Model Simulations of Solar Geoengineering

    Science.gov (United States)

    Dagon, Katherine; Schrag, Daniel P.

    2017-11-01

    Solar geoengineering has been shown in modeling studies to successfully mitigate global mean surface temperature changes from greenhouse warming. Changes in land surface hydrology are complicated by the direct effect of carbon dioxide (CO2) on vegetation, which alters the flux of water from the land surface to the atmosphere. Here we investigate changes in boreal summer climate variability under solar geoengineering using multiple ensembles of model simulations. We find that spatially uniform solar geoengineering creates a strong meridional gradient in the Northern Hemisphere temperature response, with less consistent patterns in precipitation, evapotranspiration, and soil moisture. Using regional summertime temperature and precipitation results across 31-member ensembles, we show a decrease in the frequency of heat waves and consecutive dry days under solar geoengineering relative to a high-CO2 world. However in some regions solar geoengineering of this amount does not completely reduce summer heat extremes relative to present day climate. In western Russia and Siberia, an increase in heat waves is connected to a decrease in surface soil moisture that favors persistent high temperatures. Heat waves decrease in the central United States and the Sahel, while the hydrologic response increases terrestrial water storage. Regional changes in soil moisture exhibit trends over time as the model adjusts to solar geoengineering, particularly in Siberia and the Sahel, leading to robust shifts in climate variance. These results suggest potential benefits and complications of large-scale uniform climate intervention schemes.

  15. Space-Derived Phenology, Retrieval and Use for Drought and Food Security Monitoring

    Science.gov (United States)

    Meroni, M.; Kayitakire, F.; Rembold, F.; Urbano, F.; Schucknecht, A.; LEO, O.

    2014-12-01

    Monitoring vegetation conditions is a critical activity for assessing food security in Africa. Rural populations relying on rain-fed agriculture and livestock grazing are highly exposed to large seasonal and inter-annual fluctuations in water availability. Monitoring the state, evolution, and productivity of vegetation, crops and pastures in particular, is important to conduct food emergency responses and plan for a long-term, resilient, development strategy in this area. The timing of onset, the duration, and the intensity of vegetation growth can be retrieved from space observations and used for food security monitoring to assess seasonal vegetation development and forecast the likely seasonal outcome when the season is ongoing. In this contribution we present a set of phenology-based remote sensing studies in support to food security analysis. Key phenological indicators are retrieved using a model-fit approach applied to SOPT-VEGETATION FAPAR time series. Remote-sensing phenology is first used to estimate i) the impact of the drought in the Horn of Africa, ii) crop yield in Tunisia and, iii) rangeland biomass production in Niger. Then the impact of the start and length of vegetation growing period on the total biomass production is assessed over the Sahel. Finally, a probabilistic approach using phenological information to forecast the occurrence of an end-of-season biomass production deficit is applied over the Sahel to map hot-spots of drought-related risk.

  16. Transport and Vertical Distribution of Urban Pollutants over the Guinean Gulf

    Science.gov (United States)

    Deroubaix, Adrien; Flamant, Cyrille; Menut, Laurent

    2017-04-01

    In the countries of the Guinean Gulf, the population has been growing rapidly during the last decades. The sustained economic growth is associated with increased emissions from traffic, industries, and households, and with high pollution levels. Particulate matter (PM10) emissions from urbanized areas are analyzed in the Guinean gulf coastal region by both models (WRF and CHIMERE) and observations during the beginning of the monsoon from May to July. From the Guinean gulf coast to the Sahel, the urban PM10 concentrations are highest in June, and they display frequent northward transport events. These urban pollution transport events occurred over the entire Guinean Gulf coastal region with a zonal gradient of low concentration in Abidjan to high concentration in Lagos. The main drivers are the absence of precipitation and low wind associated with the low boundary layer height. The major part of the urban pollution is transported at night in the surface layer (3 m/s), but a significant part of the pollution is caught by the low level jet and transported rapidly (15 m/s). All these results highlight specific atmospheric conditions leading to high urban pollution events along the coast and to pollution transport reaching the Sahel, which may severely impact human health.

  17. Coexistence and performance of diploid and polyploid Acacia senegal (L.) Willd

    DEFF Research Database (Denmark)

    Diallo, Adja Madjiguene

    Polyploidy is defined as possession of more than two sets of chromosomes of an organism. It is known to play a major role in evolution of organisms, but few studies are available on Sahelian trees. In the case of Acacia senegal (distributed across the Sahel), it is important to clarify the potent......Polyploidy is defined as possession of more than two sets of chromosomes of an organism. It is known to play a major role in evolution of organisms, but few studies are available on Sahelian trees. In the case of Acacia senegal (distributed across the Sahel), it is important to clarify...... revealed polyploidy in A. senegal. Estimation of the frequency of polyploids were also made among four natural populations based on trees planted in a progeny trial located in dry and hot region of Senegal; Dahra: annual rainfall trees were observed...... in all tested populations. In this study the growth rate of each tree could be estimated very precisely, because the sampled trees were part of a research trial, and the comparison between cytotypes in the progeny trial showed significantly higher growth rate of polyploids compared to diploid...

  18. Statistical and dynamical assessment of land-ocean-atmosphere interactions across North Africa

    Science.gov (United States)

    Yu, Yan

    North Africa is highly vulnerable to hydrologic variability and extremes, including impacts of climate change. The current understanding of oceanic versus terrestrial drivers of North African droughts and pluvials is largely model-based, with vast disagreement among models in terms of the simulated oceanic impacts and vegetation feedbacks. Regarding oceanic impacts, the relative importance of the tropical Pacific, tropical Indian, and tropical Atlantic Oceans in regulating the North African rainfall variability, as well as the underlying mechanism, remains debated among different modeling studies. Classic theory of land-atmosphere interactions across the Sahel ecotone, largely based on climate modeling experiments, has promoted positive vegetation-rainfall feedbacks associated with a dominant surface albedo mechanism. However, neither the proposed positive vegetation-rainfall feedback with its underlying albedo mechanism, nor its relative importance compared with oceanic drivers, has been convincingly demonstrated up to now using observational data. Here, the multivariate Generalized Equilibrium Feedback Assessment (GEFA) is applied in order to identify the observed oceanic and terrestrial drivers of North African climate and quantify their impacts. The reliability of the statistical GEFA method is first evaluated against dynamical experiments within the Community Earth System Model (CESM). In order to reduce the sampling error caused by short data records, the traditional GEFA approach is refined through stepwise GEFA, in which unimportant forcings are dropped through stepwise selection. In order to evaluate GEFA's reliability in capturing oceanic impacts, the atmospheric response to a sea-surface temperature (SST) forcing across the tropical Pacific, tropical Indian, and tropical Atlantic Ocean is estimated independently through ensembles of dynamical experiments and compared with GEFA-based assessments. Furthermore, GEFA's performance in capturing terrestrial

  19. Long-distance autumn migration across the Sahara by painted lady butterflies: exploiting resource pulses in the tropical savannah.

    Science.gov (United States)

    Stefanescu, Constantí; Soto, David X; Talavera, Gerard; Vila, Roger; Hobson, Keith A

    2016-10-01

    The painted lady, Vanessa cardui, is a migratory butterfly that performs an annual multi-generational migration between Europe and North Africa. Its seasonal appearance south of the Sahara in autumn is well known and has led to the suggestion that it results from extremely long migratory flights by European butterflies to seasonally exploit the Sahel and the tropical savannah. However, this possibility has remained unproven. Here, we analyse the isotopic composition of butterflies from seven European and seven African countries to provide new support for this hypothesis. Each individual was assigned a geographical natal origin, based on its wing stable hydrogen isotope (δ 2 H w ) value and a predicted δ 2 H w basemap for Europe and northern Africa. Natal assignments of autumn migrants collected south of the Sahara confirmed long-distance movements (of 4000 km or more) starting in Europe. Samples from Maghreb revealed a mixed origin of migrants, with most individuals with a European origin, but others having originated in the Sahel. Therefore, autumn movements are not only directed to northwestern Africa, but also include southward and northward flights across the Sahara. Through this remarkable behaviour, the productive but highly seasonal region south of the Sahara is incorporated into the migratory circuit of V. cardui. © 2016 The Author(s).

  20. Comparative Morpho-Biochemical Responses of Wheat Cultivars Sensitive and Tolerant to Water Stress

    Directory of Open Access Journals (Sweden)

    Heshmat S. Aldesuquy

    2014-05-01

    Full Text Available Water stress is likely the most important factor that adversely affects plant growth and development. In this study two wheat cultivars Gemmieza-7 (sensitive and Sahel-1 (tolerant were subjected to water stress and compared in terms of growth parameters (growth vigor of root and shoot, water relations (relative water content and saturation water deficit and protein as well as nucleic acids (DNA and RNA content in flag leaves of both cultivars. In general, water stress caused noticeable reduction in almost all growth criteria of root, shoot and flag leaf which was consistent with the progressive alteration in water relations, protein and nucleic acids content of both cultivars during grain filling. Furthermore, degree of leaf succulence and degree of leaf sclerophylly were severely affected by water stress in both wheat cultivars. In relation to wheat cultivar, the sensitive was more affected by water stress than the tolerant one. Generally, the application of salicylic acid, trehalose or their interaction induced marked increase in growth vigor of root and shoot, water relations and protein as well as nucleic acids in flag leaves of both wheat cultivars in compare with control and water stressed plants. In conclusion, Sahel-1 has suitable mechanisms to enable it to respond more effectively to water stress than Gemmieza-7.