The Study of Watershed Measures Impacts on Surface Runoff Routing by use of Multiple Flow Direction Algorithm

One of the most important problems in schematization and watershed management is determining the watershed measures impacts on flow distribution. Flow distribution algorithms grouped into two main types include Single Flow Direction (SFD) algorithm and Multiple Flow Direction (MFD) algorithms. In many package of GIS use the Single Flow Direction to runoff routing. In this research studied watershed measures impacts on surface runoff routing by use of Multiple Flow Direction Algorithm in Kakhk Experimental Watershed of Gonabad County. Moreover explain the procedure of running and calculating this algorithm in the Geographical Information Systems (GIS). For this purpose, the runoff surface generated during the years 2009 to 2014 were simulate for the scenario under watershed measures and no measures. Result showed maximum 97.1 percent and minimum 64.3 percent the flow volume of rainfall events by use of the Multiple Flow Direction methods can be simulated and estimated the flow total volume in outlet. In addition, the results showed, in showers that rainfall and flow volume amounts are small, watershed measures reduced 100 percent of the flow total output. But in flow with large volume those reduced between 38.2 to 74.2 percent of the flow total output.