Influence of intensive agriculture and geological heterogeneity on the recharge of an arid aquifer system (Saq–Ram, Arabian Peninsula) inferred from GRACE data

Abstract. This study assesses the detailed water budget of Saq–Ram Aquifer System (520 000 km2) over 2002–2019 period using satellite gravity data from Gravity Recovery And Climate Experiment (GRACE). The three existing GRACE solutions were tested for their local compatibility to compute groundwater storage (GWS) variations in combination with soil moisture datasets available land surface models (LSMs) Global Land Data Assimilation (GLDAS). Accounting pumping, artificial recharge, and natural discharge uniformly distributed domain, GRACE-derived mass balance calculation yields a long-term estimate domain-averaged recharge (2.4±1.4) mm yr−1, corresponding (4.4±2.6) % annual average rainfall (AAR). Beyond regional-scale approach proposed here, spatial heterogeneities regarding identified. first source heterogeneity is anthropogenic origin: chiefly induced by irrigation excess irrigated surfaces (about 1 domain), corresponds half total aquifer. second identified here natural: volcanic lava deposits (called harrats on Arabian Peninsula) which cover 8 aquifer domain but contribute more than 50 recharge. Hence, addition this application Peninsula, strongly indicates major control geological context arid has been poorly discussed hitherto. Due large lag times diffuse mechanism, analysis GRACE–GLDAS domains should be limited areas where focused main while valid regardless mechanism. Moreover, it appears that about 15 years records are required obtain relevant estimate.