Determination of spatial pattern of wheat and alfalfa using groundwater quality (Case study: Shahrekord plain)

A cultivation pattern in accordance with environmental conditions that reduces pollution of water and soil resources is one of the most important management strategies. This study aimed to simultaneously combine information related to soil, climate, crops and determine the potential of vulnerability and contamination of the aquifer, based on which susceptible cultivated areas (main cultivation -wheat and alfalfa) were evaluated. ArcGIS 10.3 software was used to investigate the effect of aquifer quality on cropping patterns. Climatic factors, soil parameters, and topographic characteristics were selected as effective parameters in selecting suitable cultivation sites. Nitrate content was collected in 46 wells in Shahrekord plain and averaged by kriging method, and a nitrate concentration map was obtained and combined with vulnerability map and aquifer quality area was investigated. Analytical Hierarchy Process was used to weight and finally, the layers were combined using the weighted linear combinationmethod. The results showed that areas without risk of contamination and with very low potential for contamination were 11 and 51%. Areas with low and medium to high risk of ontamination were 3 and 4%, respectively. About 25% of the aquifer area is in the high nitrate contamination range and its maximum nitrate concentration is 55 mg/l. Very high pollution (more than 75 mg/l) has not been estimated in Shahrekord plain aquifer. According to the results of this study, in terms of aquifer quality, the main part of the aquifer, about 41%, is in the safe range. 33% were classified in the low-risk group and 25% in the dangerous range. In Shahrekord plain, currently 4989 hectares are the area under irrigated wheat cultivation, which according to the results, can be increased to about 22,600 hectares. The current area under alfalfa is 3806 hectares, which according to the results, has the potential to increase the area under 28198 hectares.