Assessment of the Groundwater Resources Balancing Using Sustainability Indicators

One of the approaches to equilibrium assessment is the use of quantitative and qualitative indicators that can be a good tool. In this study, in order to evaluate the equilibrium scenarios in Hashtgerd aquifer, two indicators of intrinsic vulnerability of the aquifer and quantitative stability index of the aquifer were used. Five scenarios were defined based on the groundwater resources balancing scheme in the region and simulated using the MODFLOW numerical model. Equilibrium was calculated by combining three indicators of reliability, vulnerability and desirability of groundwater system stability index in different scenarios. The simulation results and application of different scenarios showed that by reducing the water withdrawal by 15 percent, the highest level of stability is created in the aquifer system and the system stability rate increases from 55 percent to 87 percent. The extent of changes in the aquifer stability index as a distribution in the observation wells also indicates that the middle part of the aquifer has the highest status of improving the stability index. This region, with its high density of exploitation wells, is most affected by the reduction of aquifer withdrawals. The results obtained from the aquifer stability index, considering the spatial distribution, show the feasibility of implementing different scenarios. On the other hand, due to the importance of development and the use of vulnerability indicators, the drastic index was analyzed at the regional level. The results showed that the upstream part of the aquifer has the highest level of vulnerability due to hydrogeological characteristics and the level of vulnerability has decreased in the direction of groundwater flow.