Technical note: Effect of mechanical measures on peak flow of Boostan Dam ‎Watershed using Watershed Modeling System

The aim of this study was to evaluate the effects of mechanical watershed management ýmeasures implemented across the Boostan Dam Watershed on reduction of flood peak. To this ýend, the Watershed Modeling System (WMS) was used to compare peak flow before and after ýof implementation of the measures. The mechanical measures have been implemented during ýý2000–2007. The major soil and water conservation measures in the Boostan Dam Watershed ýwere mechanical and biological measures implemented in a limited area. To determine the ýeffect of these measures, the watershed has been modeled in WMS environment. Five flood ýevents occurred before implementation of the measures were used for calibration and validation ýof the model. Three other flood events occurred after completion of the measures were then ýused for the evaluation. The results showed that the mechanical measures, despite the fact that ýtheir reservoirs are full of sediment, decrease the average peak flow 1.79 % compared to the ýabsence of these measures and if some structures would not be destructed, the reduction would ýreach 5.95 percent. It should be noted that if the structures were out of sediment, the average ýpeak flow rate would decrease 3.25 % in comparison with current situation and 7.64 % when ýcompared to absence of structuresý.