Application of MODFLOW and MT3DMS Models to Evaluate Groundwater Quantity and Quality in Northern Iran

Abstract

In recent decades, climate change and drought have led to an increase in groundwater use in the world. In Iran, due to being in the global dry belt and also the impact of climate change, reduced rainfall and surface water, excessive use of groundwater, the amount of this valuable resource has decreased. According to groundwater changes which have led to aquifer storage reduction, aquifers’ evaluation is necessary. In this study, Haraz alluvial fan, located in the north of Iran, was studied using GMS software, MODFLOW and MT3DMS models to simulate groundwater quantity and quality, respectively. . MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions. MT3DMS can be used to simulate changes in concentrations of miscible contaminants in groundwater considering advection, dispersion, diffusion and some basic chemical reactions, with various types of boundary conditions. The results of the MODFLOW model showed maximum water level in the southern part of the alluvial fan with 125.07 m and lowest in the northern part, adjacent to the Caspian Sea coast with -17.52 m. Also on MT3DMS model output which was prepared based on Cl concentration, maximum amount of this agent is 297.17 mg/lit in the East and the North-West of the study area. Management policy applied was utilization of the alluvial fan aquifer within 2020 as much as previous year. Model predictions indicated that water level in piezometers increased 0.75 m during 2021 and the maximum amount of Cl concentration remain unchanged. According to the results,

Keywords

• groundwater evaluation
• gms
• modflow
• mt3dms
• caspian sea