Abstract
Water scarcity for smallholder farming in West Africa has led to the shift of cultivation from uplands to inland valleys. This study investigates the impacts of climate and land use/land cover (LULC) change on water resources in an intensively instrumented inland valley catchment in Southwestern Burkina Faso. An ensemble of five regional climate models (RCMs) and two climate scenarios (RCP 4.5 and RCP 8.5) was utilized to drive a physically-based hydrological model WaSiM after calibration and validation. The impact of climate change was quantified by comparing the projected period (2021–2050) and a reference period (1971–2000). The result showed a large uncertainty in the future change of runoff between the RCMs. Three models projected an increase in the total runoff from +12% to +95%, whereas two models predicted a decrease from −44% to −24%. Surface runoff was projected to show the highest relative change compared to the other runoff components. The projected LULC 2019, 2025, and 2030 were estimated based on historical LULC change (1990–2013) using the Land Change Modeler (LCM). A gradual conversion of savanna to cropland was shown, with annual rates rom 1 to 3.3%. WaSiM was used to simulate a gradual increase in runoff with time caused by this land use change. The combined climate and land use change was estimated using LULC-2013 in the reference period and LULC-2030 as future land use. The results suggest that land use change exacerbates the increase in total runoff. The increase in runoff was found to be +158% compared to the reference period but only +52% without land use change impacts. This stresses the fact that land use change impact is not negligible in this area, and climate change impact assessments without land use change analysis might be misleading. The results of this study can be used as input to water management models in order to derive strategies to cope with present and future water scarcities for smallholder farming in the investigated area.
Highlights
Sustainable water and land resource management is crucial for poverty reduction, food security, and ecosystem preservation in West Africa, where the majority of the population earn their livelihood from rainfed agriculture [1,2,3,4]
The hydrological impacts of climate and land use change were investigated in an inland valley catchment using five regional climate models (RCMs)–global climate models (GCMs) under RCP 4.5 and RCP 8.5 greenhouse
The hydrological impacts of climate and land use change were investigated in an inland valley catchment using five RCM–GCMs under RCP 4.5 and RCP 8.5 greenhouse gas forcing
Summary
Sustainable water and land resource management is crucial for poverty reduction, food security, and ecosystem preservation in West Africa, where the majority of the population earn their livelihood from rainfed agriculture [1,2,3,4]. The region has experienced high variability in rainfall during the last five decades and is expected to be the most impacted worldwide by climate change in the twenty first century [5,6,7,8,9,10,11,12]. Regional climate models (RCMs) have been increasingly utilized to assess the hydrological impacts of climate change because they can be applied at a higher spatial resolution (from 0.11◦ to 0.44◦ ) compared to global climate models (GCMs) [13]. They better represent variations of land surface, vegetation, topography, and coast-line compared to GCMs [14]. A coherence between climate variables, especially precipitation and temperature, can be conserved [13,15]
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