Evaluating groundwater balance and its spatial Distribution as part of NASA GRACE mission for Blue Nile River (Ethiopia, East Africa)

Abstract

The paper introduces a methodology for estimating groundwater balance on the example of the Blue Nile basin by means of NASA GRACE space technologies. The international Gravity Recovery and Climate Experiment (GRACE) was launched in 2002 to measure time-space variations in the Earth's gravity field. It is a system for remote determination of changes in gravitational force associated with variations of mass within the Earth. The study involves a gravity recovery and climate experiment together with The Global Land Data Assimilation System to calculate groundwater storage as applied to the Blue Nile River basin, based on processing satellite data and spatial localization of the Blue Nile River using an optimal window function with specific scan line. Groundwater storage and its dynamics were investigated from 2003 to 2010. Considering surface water storage, surface runoff and soil moisture, the authors estimated groundwater budget in the Blue Nile River basin. According to the obtained results, the average groundwater storage in the area under study comprised 1100.0 mm/year. Due to a lack of land hydrological studies, verification of the data obtained was not carried out, but was recommended as a matter for future research in this area.