Land clearance and hydrological change in the Sahel: SW Niger

Leblanc, Marc; Favreau, Guillaume; Massuel, Sylvain; Tweed, Sarah; Loireau, Maud; Cappelaere, Bernard

doi:10.1016/j.gloplacha.2007.08.011

Cited by 193 publications

(199 citation statements)

References 59 publications

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“…Similarly, the distinctive geomorphological pattern of plateau and valleys in southwestern Niger results in considerable run-off and bare soil exposure (42). This finding, together with intense anthropological influences in the highly populated area near Niamey, could explain both the low S L and low S S of watersheds in the southwestern Niger region.…”

Section: Modelmentioning

confidence: 92%

On regreening and degradation in Sahelian watersheds

Kaptué

Prihodko

Hanan

2015

Proc. Natl. Acad. Sci. U.S.A.

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Over many decades our understanding of the impacts of intermittent drought in water-limited environments like the West African Sahel has been influenced by a narrative of overgrazing and human-induced desertification. The desertification narrative has persisted in both scientific and popular conception, such that recent regional-scale recovery ("regreening") and local success stories (community-led conservation efforts) in the Sahel, following the severe droughts of the 1970s-1980s, are sometimes ignored. Here we report a study of watershed-scale vegetation dynamics in 260 watersheds, sampled in four regions of Senegal, Mali, and Niger from 1983-2012, using satellite-derived vegetation indices as a proxy for net primary production. In response to earlier controversy, we first examine the shape of the rainfall-net primary production relationship and how it impacts conclusions regarding greening or degradation. We conclude that the choice of functional relationship has little quantitative impact on our ability to infer greening or degradation trends. We then present an approach to analyze changes in long-term (decade-scale) average rain-use efficiency (an indicator of slowly responding vegetation structural changes) relative to changes in interannual-scale rainfall sensitivity (an indicator of landscape ability to respond rapidly to rainfall variability) to infer trends in greening/degradation of the watersheds in our sample regions. The predominance of increasing rain-use efficiency in our data supports earlier reports of a "greening" trend across the Sahel. However, there are strong regional differences in the extent and direction of change, and in the apparent role of changing woody and herbaceous components in driving those temporal trends.Sahel | desertification | rain-use efficiency | drylands | West Africa

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Section: Modelmentioning

confidence: 92%

On regreening and degradation in Sahelian watersheds

Kaptué

Prihodko

Hanan

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Expected changes in these climatic attributes in most dryland regions will likely reduce the productivity of both crops and natural vegetation. This will not only affect food production and security, but also will have key implications for soil conservation and climate regulation, given the strong impacts of vegetation and its development on processes such as soil erosion, nutrient cycling, carbon sequestration and water run-off and infiltration [5,95,111,112]. Such impacts may act synergistically with global change-induced biodiversity losses, as biodiversity is crucial for maintaining ecosystem services in drylands [19,131].…”

Section: Global Environmental Change Effects On Drylandsmentioning

confidence: 99%

It is getting hotter in here: determining and projecting the impacts of global environmental change on drylands

Maestre

Salguero‐Gómez

Quero

2012

Phil. Trans. R. Soc. B

264

209

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Drylands occupy large portions of the Earth, and are a key terrestrial biome from the socio-ecological point of view. In spite of their extent and importance, the impacts of global environmental change on them remain poorly understood. In this introduction, we review some of the main expected impacts of global change in drylands, quantify research efforts on the topic, and highlight how the articles included in this theme issue contribute to fill current gaps in our knowledge. Our literature analyses identify key under-studied areas that need more research (e.g. countries such as Mauritania, Mali, Burkina Faso, Chad and Somalia, and deserts such as the Thar, Kavir and Taklamakan), and indicate that most global change research carried out to date in drylands has been done on a unidisciplinary basis. The contributions included here use a wide array of organisms (from micro-organisms to humans), spatial scales (from local to global) and topics (from plant demography to poverty alleviation) to examine key issues to the socio-ecological impacts of global change in drylands. These papers highlight the complexities and difficulties associated with the prediction of such impacts. They also identify the increased use of long-term experiments and multidisciplinary approaches as priority areas for future dryland research. Major advances in our ability to predict and understand global change impacts on drylands can be achieved by explicitly considering how the responses of individuals, populations and communities will in turn affect ecosystem services. Future research should explore linkages between these responses and their effects on water and climate, as well as the provisioning of services for human development and well-being.

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“…The effect of the change is estimated based on the differences between the runoff hydrographs simulated in the initial and "changed" conditions, respectively. Several studies have utilized the RS-GIS-Modeling approach for assessing the impacts of land-cover change to the hydrologic response of watersheds to rainfall events (e.g., [1,[12][13][14]). However, the majority of studies focus on modeling the hydrological response of watersheds to future changes in land-cover.…”

Section: Remote Sensing and Gis In Watershed Researchmentioning

confidence: 99%

Integrated Landsat Image Analysis and Hydrologic Modeling to Detect Impacts of 25-Year Land-Cover Change on Surface Runoff in a Philippine Watershed

2011

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Landsat MSS and ETM+ images were analyzed to detect 25-year land-cover change in the critical Taguibo Watershed in Mindanao Island, Southern Philippines. This watershed has experienced historical modifications of its land-cover due to the presence of logging industries in the 1950s, and continuous deforestation due to illegal logging and slash-and-burn agriculture in the present time. To estimate the impacts of land-cover change on watershed runoff, land-cover information derived from the Landsat images was utilized to parameterize a GIS-based hydrologic model. The model was then calibrated with field-measured discharge data and used to simulate the responses of the watershed in its year 2001 and year 1976 land-cover conditions. The availability of land-cover information on the most recent state of the watershed from the Landsat ETM+ image made it possible to locate areas for rehabilitation such as barren and logged-over areas. We then created a "rehabilitated" land-cover condition map of the watershed (re-forestation of logged-over areas and agro-forestation of barren areas) and used it to parameterize the model and predict the runoff responses of the watershed. Model results showed that changes in land-cover from 1976 to 2001 were directly related to the significant increase in surface runoff. Runoff predictions showed that a full rehabilitation of the watershed, especially in barren and logged-over areas, will be likely to reduce the generation of a huge volume of runoff during rainfall events. The results of this study have OPEN ACCESSRemote Sens. 2011, 3 1068 demonstrated the usefulness of multi-temporal Landsat images in detecting land-cover change, in identifying areas for rehabilitation, and in evaluating rehabilitation strategies for management of tropical watersheds through its use in hydrologic modeling.

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Land clearance and hydrological change in the Sahel: SW Niger

Cited by 193 publications

References 59 publications

On regreening and degradation in Sahelian watersheds

On regreening and degradation in Sahelian watersheds

It is getting hotter in here: determining and projecting the impacts of global environmental change on drylands

Integrated Landsat Image Analysis and Hydrologic Modeling to Detect Impacts of 25-Year Land-Cover Change on Surface Runoff in a Philippine Watershed

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