17. Mapping Groundwater Potential Zones in UAE Using GIS-Based Hydrogeological Modeling

According to recent estimations, the UAE’s fresh groundwater resources are extremely limited and have a very short shelf life if things continue as they are. With and without augmentation, the total recharge to the Quaternary aquifer is 1197 and 1001 MCM, but the annual total groundwater extraction is greater than 2860 MCM. In agricultural areas, it also revealed that the quaternary aquifer’s replenishment ratio ranges from 1 to 40%. Even though this is a general conclusion, it is necessary to approach groundwater resources in each region in a unique way. Implementing the required regulations is important to alter the current practice and give water based on the crop’s water needs. Contrarily, brackish groundwater is plentiful when compared to fresh groundwater. Around 200 BCM is a reservoir of brackish groundwater with a salinity of less than 15,000 mg/l. When used for agriculture development, this type of water should be treated as a precious resource and conserved. To identify the groundwater potential zones, all of the thematic maps were overlaid using the spatial analysis tool in ArcGIS 10.3. By using the AHP approach, the groundwater conditions in the farming areas in UAE were categorized into six groundwater potential zones (GWPZs)) based on the groundwater reserve, overall salinity, distance to existing farms (pumping wells), ratio of the present saturated thickness/max saturated thickness, and remaining lifetime. According to the results, the groundwater potential zones 1 and 2—which have TDS levels less than 2000 mg/L and between 2000 and 5000 mg/L, respectively cover areas of 40 and 50 km². In GWPZ1 and GWPOZ2, the estimated groundwater reserves are 581 and 640 MCM, respectively. Medium (5000 TDS–10,000 mg/L) and highly brackish (10,000 TDS–15,000 mg/L) groundwater potential zones, respectively, span 934 and 913 km². Zones 3 and 4 have a total groundwater reserve of around 28,000 MCM, demonstrating their critical role as the only inland source of irrigation water with preventative desalination. In general, the area of arable lands and the available fresh groundwater resources are very limited.