Development of a groundwater flow model for the highly parameterized Qatar aquifers

Groundwater models are powerful tools for water resources management, assessment and protection. The main challenge facing model development is the calibration process, especially in large models with a high number of calibrated parameters. Qatar aquifers comprise karst limestone with lots of cavities, sinkholes and underground channels. Therefore, the aquifer is highly heterogeneous. This study presents the development of a regional scale groundwater flow model for the entire country of Qatar, with emphasis on calibration process. Pilot points approach with regularization has been utilized to calibrate the model to re-produce historical water levels representing steady state conditions. Hydraulic conductivity and natural rainfall recharge were calibrated, using historical groundwater levels from 1958. Results of the model included predevelopment water budget for the country, and estimation of natural groundwater recharge, which was found to be 65.6 million m(3) per year. Calibration process also reveals that the top layer of the aquifer, and the northern part have the highest hydraulic conductivity, compared to other areas. The calibrated hydraulic conductivity values are quite variable, as it ranges from 0.1 m/days to more than 200 m/days. Results of this model can help understanding the flow regime, aquifer parameterization and design of artificial recharge scheme in Qatar.