Ayyub Moradi; Ali Najafinejad; Majid Ownegh; Choghi Bairam Komaki
Abstract
Simulation of runoff and sediment in watersheds require different modelling approaches, each provided for certain condition. Semi-distributed hydrological model (SWAT model) is one of the most widely used modelling approaches in this context. Among the most important spatial information needed by SWAT ...
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Simulation of runoff and sediment in watersheds require different modelling approaches, each provided for certain condition. Semi-distributed hydrological model (SWAT model) is one of the most widely used modelling approaches in this context. Among the most important spatial information needed by SWAT model, is the map of digital elevation model (DEM) which plays an important role in the model results for the exploration of hydrographic properties of watersheds, estimation of the spatial distribution of runoff and sediment load and its accuracy. The aim of this study was to evaluate the effect of different digital elevation models on runoff and suspended sediment in Galikesh watershed, Golestan Province. For this purpose, three types of DEM with the spatial resolutions of 30, 90 and 1000 meters were selected and for a period of 27 years, SWAT model was implemented. SWAT-CUP software and SUFI2 method were used for the model calibration and validation. Nash-Sutcliffe (NS) criterion for discharge and in calibration phase (1990-2007) for the resolutions of 30, 90 and 1,000 meters, was obtained respectively, 0.63, 0.63 and 0.62 and for suspended was obtained respectively 0.69, 0.68 and 0.67 which is considered satisfactory, given the presumed numerical ranges acquired from the previous studies. The amounts of watershed’s annual runoff for the resolutions of 30, 90 and 1000 meters, were respectively, 11.23, 11.30 and 11.39. The results that the use of different of digital elevation models would result in essentially similar results in runoff and sediment estimations, although changes in suspended sediment was slightly overestimated. This is attributable to the inverse modelling logic and lack of considering the parameters which arise directly from the DEM map. , due to data limitations in the Swat model calibration, the digital elevation model used to simulate the runoff did not have much impact on runoff and sediment estimations.
Nafiseh Moghaddasi; Vahedberdi Sheikh; Ali Najafinejad; Iman Karimirad
Abstract
The aim of this study was to evaluate the effects of mechanical watershed management measures implemented across the Boostan Dam Watershed on reduction of flood peak. To this end, the Watershed Modeling System (WMS) was used to compare peak flow before and after of implementation of the ...
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The aim of this study was to evaluate the effects of mechanical watershed management measures implemented across the Boostan Dam Watershed on reduction of flood peak. To this end, the Watershed Modeling System (WMS) was used to compare peak flow before and after of implementation of the measures. The mechanical measures have been implemented during 2000–2007. The major soil and water conservation measures in the Boostan Dam Watershed were mechanical and biological measures implemented in a limited area. To determine the effect of these measures, the watershed has been modeled in WMS environment. Five flood events occurred before implementation of the measures were used for calibration and validation of the model. Three other flood events occurred after completion of the measures were then used for the evaluation. The results showed that the mechanical measures, despite the fact that their reservoirs are full of sediment, decrease the average peak flow 1.79 % compared to the absence of these measures and if some structures would not be destructed, the reduction would reach 5.95 percent. It should be noted that if the structures were out of sediment, the average peak flow rate would decrease 3.25 % in comparison with current situation and 7.64 % when compared to absence of structures.
