Browsing by Author "Tolosa, Dejene"
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Item Spatiotemporal variation of Groundwater storage by using GRACE data: In case of East Africa(Addis Ababa University, 2022-06) Tolosa, Dejene; Tulu, Besha (PhD)The Gravity recovery and climate experiment (GRACE and GRACE FO) satellite mission is very important to monitor Groundwater storage variation where there is a limitation of in situ data and limit of policies for sharing data like East Africa. In this study, GRACE and GRACE FO and GLDAS data were carefully processed and filtered by Gaussian smoothing methods to reduce noise. This study correlates GRACE derived TWSA data with water balance (P-ET-R) over 2008 to 2019 (means, twelve years) period and strong correlation(r = 0.75, rmse = 2.198) were obtained. GLDAS land surface model is used to get soil moisture and plant canopy surface water that reduced from GEACE/GRACE FO derived TWSA to obtained Groundwater storage change of the study area. In addition to that, Global land data assimilation system version 2.2 groundwater storage change was used. To analysis Groundwater storage change, the study area was classified according to river basin in the study area. Therefore, three basins were considered for the area and correlation coefficients were individually determined to measure the strength between the two data analyzed. Accordingly, GWSA of GRACE-GLDAS and GLDASv2.2 have a correlation coefficient value of 0.88, 0.975 and 0.906 for Nile, Jubba-Shebelle, and Lake Rudolf basins respectively. The largest yearly ground water depletion occurs in February, 2008 to February, 2010 during millennium drought by average rate of -9.2 mm per year in Jubba Shebelle basin and February, 2009 to June, 2010 by -17.98 mm per year in Nile basin and June, 2008 to December 2009 by -12.16 mm year for Lake Rudolf basins due to decreasing of rainfall.