Assessment of groundwater vulnerability in Nekarod plain using DRASTIC model

The atmospheric conditions and rainfall shortage have increased the utilization of groundwater resources in the northern regions of the country. Therefore, the evaluation of groundwater resources in the aquifer of the Nekarood plain is of great importance due to the high use of groundwater resources and subsequent use of chemical agents such as fertilizers and pesticides in agricultural lands. The purpose of this study is assessing the vulnerability of aquifer Nekarood area in Mazandaran province with the DRASTIC model.

In this study the potential of groundwater contamination was evaluated with the DRASTIC model. This model evaluates the groundwater potential with seven different parameters (Depth, Net nutrition, Aquifer media, Soil media, Topography, Non-saturated media, Hydraulic conductivity). In this study, the weights of each of these parameters were first determined using the layer overlay method in GIS for each of the seven parameters and the desired range. Then, the columns of each of the ranges in the GIS were converted to the Raster layer and using the Raster calculator, the total number of layers with the obtained weight was summed up and the risk maps were finalized in the region according to the model of the DRASTIC model. To illustrate the variation of water quality elements using the Kriging statistical method, to determine the correlation and verbose of the results of the DRASTIC model, the SPSS 22 software was used to determine the final stroke index with nitrate, pH and EC parameters.

The results of the evaluation with the DRASTIC model in the area of Nekarood showed that the area with a high vulnerability only 17.33% of the total area of the region and region with low vulnerability potential includes52.97%. Pearson statistical test was used to show the relationship between the results of the DRASTIC model and the values of nitrate, pH and EC. The results of the test showed that the relationship between the DRASTIC model with the values of nitrate, PH and EC is 0.610, 0.254 and 0.277, respectively. The Nekarood plain is one of the major contaminated areas due to the use of pesticides and chemical fertilizers with the aim of increasing the yield of agricultural products. According to the results of the model, the southeastern range of the region has a high vulnerability due to the different texture and physical conditions of the soil, and the north-east to a part of the center of the plain has a low vulnerability. Downstream areas have a more coarse texture than the southeastern part, and this is due to the movement of materials to the sea level so there is less pollution. By verifying the model of the DRASTIC and determining the coefficient of correlation between the values of the model, it was determined that the model is in line with the qualitative elements and a scientific strategy for studying and determining the sensitivity of the aquifer in the region.