Effect of Artificial (Pond) Recharge on the Salinity and Groundwater Level in Al-Dibdibba Aquifer in Iraq Using Treated Wastewater

Abstract

Groundwater is one of the most important water resources in Iraq, so efficient management of storage, recharge, and consumption rates is required, for maintaining the sustainability of groundwater supplies. Some of the most valuable methods for ensuring the long-term sustainability of groundwater aquifers are those that provide artificial recharge. This study was conducted to determine the effect of artificial recharge on groundwater levels and quality in Iraq’s Dibdibba unconfined aquifer, utilizing groundwater modeling system software (GMS). Reclaimed water (tertiary treatment) from Kerbala’s central wastewater treatment plant (WWTP) was used as raw water to recharge the aquifer. The effects of this artificial recharge were determined using built-up groundwater flow (MODFLOW) and dissolved transport (MT3DMS) simulation models. Model calibration and validation were implemented based on groundwater monitoring data from 2016 to 2017. The model matched observed elevations at R2 = 0.96 for steady state and R2 = 0.92 in transient state simulations. After the 3D numerical model was calibrated and validated, two scenarios were explored based on the daily production of 5000 and 10,000 m3/d from Karbala’s WWTP. The results indicated that the pumping of the treated wastewater through the pond would increase water levels by more than 20 cm for more than 78.2 and 110 km2 for pumping rates of 5000 and 10,000 m3/day, respectively. More than 40 km2 would be added (reclaimed) to the agricultural areas in the region as a result of the use of artificial recharge using a pond. Groundwater quality was also improved, as the TDS decreased by more than 55%, down to 1900 ppm, and the EC decreased by more than 68%, down to 1500 µ.S/cm. The findings of this study can assist decision-makers in developing strategies to reduce water scarcity and adapt to climate change.