Gravity observations can be used to monitor the groundwater storage variations, through the traditional techniques, which are very difficult due to high cost and strong labor intensity. The system Gravity Recovery and Climate Experiment (GRACE) measures gravity anomalies on the earth to estimate changes in Terrestrial Water Storage (ΔTWS) for a regional area with low cost and wide coverage. GRACE data available from 2003 to 2011 but as a result of just two piezometric maps were available, so in this study, the changes in GRACE gravity data of 2003 and 2006 were used to monitor the Ground Water Storage changes (ΔGWS) in Nile Delta aquifer, which extended from 30o to 31o N and 30o to 31o E of Egypt. (ΔGWS) are obtained by subtracting the soil moisture water obtained from the hydrological models GLDAS (Global Land Data Assimilation System) from (ΔTWS), the effective parameter for study area is soil moisture. This work has the potential to improve Nile Delta Aquifer’s groundwater resource management and validate it by comparing (ΔGWS) extracted from GRACE against (ΔGWS) from two piezometric maps provided by Research Institute for Ground Water (RIGW). The results indicate that the maximum and the minimum differences between traditional techniques from piezometric maps and GRACE satellite- GLDAS model calculations are 25 and -11 mm respectively with standard deviation about 15 mm. |
