measurement and simulation of dissolved oxygen in zayande rood river

background: zayandeh-rood river is the only perennial river in the central basin of iran that has fresh water. water from this source is used for drinking, industrial and agricultural purposes. drinking water is extracted from upstream portion (upstream of chamaseman dam) of zayandeh-rood river and therefore its quality is very important. due to growth of population, industry and other factors, its management needs powerful tools such as mike model 11 to be able to simulate water quality and quantity. methods: in this research mike model 11 was used to simulate water quality and quantity in zayandeh-rood river from tanzimi dam to kalleh bridge (120 km distance). for this purpose samples were taken at four hydrometery stations along the river during five months. at each sampling location do, ph, ec, bod 1,3,5,7 , nh 4 , no 3 , po 4 3- , cod and temperature were measured. then the model was calibrated and its accuracy was investigated. the model results and measurements were statistically compared and their correlation was determined using pearson correlation test. also water quality in zayandeh-rood river was simulated under two scenarios for the next 25 years. pearson correlation indicated an appropriate correlation (approximately r = 0.9) between the model results and the field measurements. findings: the findings of this research revealed that the concentration of po 4 3- , bod, cod, and nh 4 . no 3 from tanzimi dam to kalleh bridge station exceeds surface water standards. the findings for the next 25 years scenarios indicated that due to the population and industries growth, some parameters’ concentration will be increased. this will affect both zayandeh-rood ecosystem and purifying drinking water by baba shekhali water treatment plant. conclusion: also the findings indicated that although do is within the standard level but it may affects some type of fish production and migration. keyword: do, simulation, mike 11, zayanderood