Impact of meteorological conditions on water resources in the Upper East Region of Ghana using remotely-sensed and modelled hydrological data

Study region: The Upper East Region, Ghana, West Africa, lies within the Volta Basin, floods annually, and contributes substantially to Ghana's food production. Study focus: We assessed precipitation (P), evapotranspiration (ET), and total water storage anomalies from GRACE (TWSA) and GLDAS-Noah (TWCA) to study the influence of the UER's climate on water availability between 2002 and 2017. We analysed (1) the relative uncertainties of the data sets using the triple-cornered hat method, (2) the terrestrial water budget to validate TWSA/TWCA and (3) cross- and multi-correlation analyses to study the relationship between water storage (or availability) and meteorological variables. New hydrological insights: We found strong correlations between the different P products (r > 0.96), between the different GRACE products (r > 0.95), but not between the different ET products. The hybrid P, TWSA from the Jet Propulsion Laboratory, and ET from ERA-5 had the smallest relative uncertainties. TWSA increased by 9.8 ± 0.8 mm yr⁻¹ while TWCA decreased. P and ET showed no evidence of a trend and were similarly influenced by the other meteorological variables. However, 93 of 183 months had water surplus and mean net P was positive – indicating the UER received more water than it lost. These agree with the increasing TWSA trend. The water budget validation also confirmed that GRACE can be used for water management; GLDAS-Noah underestimates storage in the UER.