Role of land use in quality of water in Zayanderood River

Zayandeh rood River flows from West to East with a length of about 350 km. This river supplies agricultural, municipal and industrial water requirements. 9 sampling stations from different sections of river was selected for evaluation of impact of land use on Water quality parameters in this region and boundary of sub-basin in each station was extracted by ArcGIS and relationship between land use of sub-basins related to each station with water quality parameters was scrutinized. Seasonal sampling was performed from summer 2013 to spring 2014 and to determine water quality, 7 parameter DO, COD, BOD, TSS, PH, NO3, and PO4 was measured. The results show a direct correlation between the decline in water quality and increased use of agricultural and industrial activities in the region. The nitrate and phosphate in stations that have a high proportion of agricultural lands continues to increase The BOD also in Zarinshahr drain, due to high activity of agricultural and industrial activities in this area has been a growing trend. The amount of dissolved oxygen in winter and autumn showed a sharp drop in the downstream stations. Also amount of TSS has increased dramatically in downstream stations in winter. Overall the results showed that water quality parameters over from upstream to downstream areas significantly reduced.