Effect of Agricultural activities on Groundwater Vulnerability: Case Study of Halabja Saidsadiq Basin, Iraq

Groundwater is one of the main sources of water in Halabja-Saidsadiq Basin of northeast Iraq. It covers an area of 1278 square kilometers with population of about 190,727.In this study, the standard DRASTIC method has been applied to generate a map of groundwater pollution vulnerability of the basin. In addition, two different scenes of landsat Thematic Mapper (TM) were used with the aid of ERDAS IMAGINE software and the GIS technique to prepare digital image classification of the study basin. Supervised classification for level I of USGS was conducted with band combination RGB/742 to prepare The Land Use and Land Cover (LULC) map. The LULC map illustrates that only five classes of land use can be identified these are: barren, agricultural, vegetation, urban and wet land or water body. The LULC map converted to LULC index map. This index map has an additional parameter added to the standard DRASTIC model to map the modified DRASTIC vulnerability in the study basin. Nitrate concentration analysis was selected and added as a pollution indicator to validate this modification. In this study, the nitrate concentration between two different seasons (dry and wet) was analyzed from (30) water wells. The standard vulnerability map of the studied basin classified the basin into four vulnerability index zones: very low (34%), low (13%), moderate (48%) and high (5%). While the combined modification classified the area into five classes: very low (1.17%), low (36.82%), moderate (17.57%), high (43.42%) and very high (1.02%). The results s that the modified DRASTIC model was dramatically superior to the standard model; therefore, the most appropriate method to apply is the combination of standard DRASTIC model with LULC index map. This conclusion is based on the results of nitrate content, as its concentration in the dry season is much lower than in the wet season.Validerad; 2015; Nivå 1; 20151024 (nadhir)