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GRACE Detected Rise of Groundwater in the Sahelian Niger River Basin
Author(s) -
Werth S.,
White D.,
Bliss D. W.
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb014845
Subject(s) - groundwater , environmental science , hydrology (agriculture) , surface water , land cover , structural basin , water storage , water resources , climate change , water resource management , water cycle , drainage basin , land use , geography , geology , environmental engineering , oceanography , paleontology , ecology , civil engineering , geotechnical engineering , cartography , engineering , inlet , biology
West African regions along the Niger River experience climate and land cover changes that affect hydrological processes and therewith the distribution of fresh water resources (WR). This study provides an investigation of long‐term changes in terrestrial water storages (TWS) of the Niger River basin and its subregions by analyzing a decade of satellite gravity data from the Gravity Recovery and Climate Experiment (GRACE) mission. The location of large trends in TWS maps of differently processed GRACE solutions points to rising groundwater stocks. Soil moisture data from a global land surface model allow separating the effect of significantly increasing amount of WR from that of TWS variations. Surface water variations from a global water storage model validated with observations from altimetry data were applied to estimate the groundwater component in WR. For the whole Niger, a rise in groundwater stocks is estimated to be 93 ± 61 km 3 between January 2003 and December 2013. A careful analysis of uncertainties in all data sets supports the significance of the groundwater rise. Our results confirm previous observations of rising water tables, indicating that effects of land cover changes on groundwater storage are relevant on basin scales. Areas with rising water storage are stocking a comfortable backup to mitigate possible future droughts and to deliver water to remote areas. This has implications for Niger water management strategies. Increasing groundwater recharges may be accompanied by reduction in water quality. This study helps to inform authority's decision to mitigate its negative impacts on local communities.