Effect of soil erosion on available phosphorus losses in a Hyrcanian watershed

One of the most important main environmental problems is soil erosion and its affects. Eutrophication, low oxygen levels and `high nutrient (nitrogen and phosphorus) concentrations in reservoirs, channel and other water courses, is a common water pollution feature. Phosphorus (P) is one of the major plant nutrients and also the major nutrients controlling eutrophication of surface water. The aim of current study was to quantities evaluation of the effect soil erosion on available phosphorus loss in Kojour watershed. Discharges resulting from storm events were sampled at one fixed point of river using the manual sampler. Results showed that minimum and maximum phosphorus loss through 7 rainfall events was 321and 6707 g respectively with an average value of 2620 g. Soil erosionThe result of modeling among phosphorus loss, sediment yieldrate in this period was dramatically affected on the loss of phosphorus. The result of modeling among phosphorus loss, sediment yield and runoff volume indicated that phosphorus loss didn’t estimate by discharge, while sediment concentration can estimate loss of phosphorus with estimation error of 26%. The results could facilitate the application of given methods obtained in the present study to other ungauged watershed with similar conditions and leading to the suitable soil and water management