An Investigation on the Closure of the Water Budget Methods Over Volta Basin Using Multi-Satellite Data

The terrestrial water budget over a particular hydrological domain (e.g., a drainage basin) plays an important role in understanding the interactions among the energy and water cycles. In this work, we assess the closure of the water budget methods [i.e., terrestrial water budget (TWB) and the coupled atmospheric-terrestrial water budget (ATWB)] as well as the control of total water storage gain over Volta Basin of West Africa. To achieve this, we explore the available satellite and data products: GRACE-derived terrestrial water storage changes (TWSC), satellite altimetry, TRMM-measured rainfall, MODIS-estimated evaporation, atmospheric moisture storage and divergence (ERA-Interim reanalysis data), and in situ discharge. The closure of water budgets are assessed by comparison with GRACE-derived TWSC. The results indicate that the closure of water budgets over the Basin, considering the agreement with GRACE-derived TWSC, present an RMSE of 33.72 and 48.22 mm/month for TWB and ATWB, respectively. This implies that the net precipitation (precipitation minus evaporation) computed from ERA-Interim reanalysis data presents high uncertainties over the Basin. Further, the significant accumulated water gain of 162.84 mm for the period of January 2003–December 2012, is 48% controlled by Lake Volta.