Sensitivity Analysis of Mixing Front Control between Saline and Fresh Groundwater in the Marvdasht-Kharameh Aquifer Using the MODPATH-MODFLOW Model

This study analyzes the sensitivity of groundwater flow and the mixing fronts of saline and fresh transient groundwater in the Marvdasht-Kherameh aquifer using the MODPATH-MODFLOW model. In groundwater flow modeling, IPCC scenarios (such as RCPs and SSPs) are used to predict climate changes, including variations in temperature and precipitation, which can directly impact groundwater levels, aquifer recharge, and groundwater flow patterns. Uncertainty analysis was conducted using the First-Order Reliability Method (FORM) to assess the aquifer's sensitivity to groundwater level changes. The findings indicate that the flood volume entering water bodies diminishes during wet and dry periods as it mixes with saline water. The critical scenario involves water infiltration into the aquifer, highlighted by FORM results, showing a homogeneous flow pattern in the affected region. Excessive groundwater extraction has led to significant flow disruption risks in concentrated healthy areas. Saline water infiltration from the wetland and lake accelerates desiccation. It maintains stable flow in the southeastern plain, leading to salt accumulation and destruction of the aquifer's recharge structure in central regions. Effective management strategies are necessary to preserve the region's ecological and hydrological balance. This research provides valuable insights into the interactions between saline and fresh groundwater and their impact on aquifer stability and wetland health.