Comparison of vulnerability potential of Aquifer of Nekarud Basin using DRASTIC, SINTACS and SI models

Groundwater is the main source of fresh water in Nekarud region of Mazandaran Province. Population growth and the development of agriculture and industries has had a negative impact on the quantitative and qualitative characteristics of underground water in Nekarudd plain. Management and of these resources is necessary and unavoidable. Therefore in order to prevent environmental damages resulting from pollution and extraction of underground water resources in this region, principled planning should be done in the region. In this research, using three models DRASTIC, SINTACS and SI, the vulnerability of Nekarud plain aquifer was evaluated. For this purpose, first, the necessary parameters for the mentioned models including groundwater depth, nutrition, unsaturated zone, soil type, aquifer environment, topography, hydraulic conductivity, and land use were assessed and scored to prepare the overlay map. The nitrate and pH data of 2013 and 2014 were also used to validate the outputs of the models. The results showed that the DRASTIC model has the highest correlation value with nitrate, which is the main cause of groundwater pollution, and the north and northwest regions of the basin has the highest vulnerability value with 52.97%. The Mann-Kendall test to determine the trend of elements also showed that there is no trend of nitrate elements. But the value of ZS index for pH in 2013 was equal to 8.638 and it has an increasing trend. This means that this index had an increasing and significant trend at the level of 0.95 in 2014. The general result showed that DRASTIC is a suitable model for evaluating the vulnerability of the plain and planners and decision makers can use it as a suitable and cost-effective solution to prevent the increase of pollution.