CLASSIFICATION OF SURFACE WATER QUALITY AND ASSESSMENT OF DOMINANT IONS ORIGIN IN HARAZ RIVER BASIN, IRAN

The physico-chemical parameters (calcium, magnesium, sodium, potassium, bicarbonate, sulphate, chloride, electrical conductivity, pH, water temperature, and dissolved oxygen) of waters from Haraz River, in Iran were analyzed during 2008. The results obtained showed that the river water quality falls within bicarbonates and carbonates classification, respectively. Ions such as calcium and bicarbonate are principally originated from weathering and decomposition of carbonate rocks and erosion of soil; or they may originate from anthropogenic activities. Mining of sand from the riverbed is among the anthropogenic sources of pollution. The concentration of ions in wet season was generally less than dry season. This might be due to the flow rate of river water during the wet season when water is more diluted in comparison to the dry season. Schoeller diagram is indicative of potable water throughout the river course. Generally, water quality of Haraz River is most appropriate for irrigation. The USSL diagram classifies water quality as low sodium-medium salinity, and low sodium-high salinity. To obtain healthy crops in areas where water contains higher salinity, suitable drainage and adequate leaching is indispensable factors. Furthermore, salinity management and selection of plants compatible with presence of salt must be taken into account.