Investigation on quantitative and qualitative changes of groundwater resources using MODFLOW and MT3DMS: a case study of Hashtgerd aquifer, Iran.

Considering the different quantitative and qualitative issues of groundwater resources, which are caused by population growth and development, the implementation of comprehensive plans and taking management measures in order to protect and restore groundwater resources are highly recommended. In this regard, the evaluations of various management measures are necessary because based on the results, it is possible to make appropriate decisions about how to control water consumption as the main part of future policies. Hashtgerd study area is located in Alborz province in Iran and requires appropriate decisions regarding how to control the intensive groundwater resources depletion and quality reduction. An average storage deficit of 4.08 million cubic meters per year was realized during 2012–2016 and water quality decreased. The present study has investigated the quantitative and qualitative changes of groundwater resources using MODFLOW and MT3DMS in response to different management schemes. Different management schemes based on a national plan called "the aquifer restoration plan" were applied for the 20-year horizon (2016–2036). It was found that by blocking unlicensed agricultural wells and modifying the licenses for licensed agricultural wells in the entire aquifer area, the storage would increase by an average of 7.23 million cubic meters per year, and nitrate and sulfate concentrations would decrease by 0.06 and 1.14 mg/l per year, respectively. Artificial recharge of the aquifer with treated wastewater was found to have a great impact on reducing pollutants and improving the water quality, though it had no desirable effect on the groundwater level. In this case, nitrate and sulfate concentrations decrease by 0.53 and 2.24 mg/l per year, respectively. [ABSTRACT FROM AUTHOR]