Groundwater Modeling of Ahmed Taher and Bakhtiari areas southwest of Khanaqin Basin in Diyala Governorate – Iraq

Abstract

A foretelling of the groundwater level declining is substantial for the administration of subsurface water resources system, particularly in dry and semi-dry zones (area under this study), in which ground-water is the main exporter for agrarian and Household requirements. The purpose of this study is to investigate the influence of the increasing withdrawal rates from the aquifer on the condition of the groundwater. In addition to the effect of the decreasing recharge rate on the groundwater for the area under study. The study area (the southwest part of Khanaqin city) extended over 129 km2 was simulated using the mathematical model (GMS10-MODFLOW2000). Under a steady-state calibration process, good matching between model and observed groundwater head values has been found. To observe and evaluate the competence of the groundwater water system, five different scenarios have been used for the unsteady state. The first case used as a reference case for comparison, in which the existing withdrawal rates were modeled, after that the discharging rates will be increased up to (50 %, 100 %, and 200%) on the current rates through the next ten years. For the fifth case, the recharge rate was decreased by up to 25% by keeping the same condition applied in the previous cases. Maximum drawdown values resulted from these scenarios are equal to (11.58, 19.14, 27.58, 46.82 and 48.35 m) respectively. According to the drawdown map, the maximum value recorded on the left side of the modeled region in the study area, and the minimum was recorded in the area near Al-Wand River.