Variation of PhysicoChemical Quality of Groundwater Watershed in Gharehsou during 2003-2012

Background and Geographic information system (GIS) and appropriate statistical method for management and analysis of groundwater has been growing rapidly. New devices and information support system has a significant role in management of water resources, especially in limited and valuable water resources. The aim of this study was to evaluate the changes in the physicochemical quality of groundwater watershed in Gharehsou during a ten year period (2003-2012). The results of water physicochemical parameters analysis were obtained from the regional water authority. The annual average of parameters were determined using descriptive statistics in SPSS Ver.16 by applying Friedman Test and MEASURE with significant level α= 0.05. The annual parameters changes were compared and zoning of different parameters for groundwater quality of gharasoo watershed was determined through ArcGIS9.3 software. The results showed that physicochemical parameters had an increasing trend during the first five years while in the next five years despite annual fluctuations a decreasing trend was observed. No significant correlation was found in annual variation of potassium, calcium, chloride, and conductivity (P> 0.05). Geographically, density and high concentration of chemical compounds in groundwater was seen more in north west, west and south west areas. The most increases of cation and anion concentrations were observed between 2005-2008. The results showed that most of the groundwater watershed contained bicarbonate, and the changes in chemical composition of groundwater watershed depended on rain fall, water harvesting, and type of soil.