Analysis of interactions of groundwater and Karun river in Gotvand-Aghili plain using MODFLOW model

In semi-arid regions water resources systems are more vulnerable due to climate change and human activities, and based on this, knowing the basics of interaction between groundwater and surface water is essential for effective management of water resources in these regions. There are several models to simulate this phenomenon, each of which has its own problems and shortcomings. This study aims to simulate groundwater flow in Gotvand - Aghili plain using the River Package of MODFLOW model. First, aquifer was simulated in steady state. Then, using the data of water table from October 2007 to September 2008 the aquifer was calibrated in the unsteady-state. Next, by using the calibrated model in unsteady-state and data of water table from October 2008 to September 2009, the model was verified. After that, the interactions between aquifer and Karun River in different scenarios including the impacted of two dams Gotvand and predicting the interaction of aquifer and the river during the dry and wet periods was investigated by zone budget method in modflow. Afterward, the Karun river reach in the study area was divided into seven zones and water balance was assessed in each of them. Results indicate that the river is draining the aquifer in the northern and especially central parts of the plain and recharging it in the southern zones. Aquifer – river exchanges are mostly affected by the river water level fluctuations.