atenakabir

The spatially distributed hydrologic model WetSpa is applied to the Dinvar river basin (1717 km2) located in upstream of the Karkheh Dam. Daily hydrometeorological data from 1382 to 1389, including precipitation data from 9 stations, temperature and evaporation data measured at 4 stations are used as input to the model. The spatial characteristic of the basin is described by three base maps, i.e. DEM, land use and soil type, in GIS form using 100 m cell size. Results of the simulations show a good agreement between calculated and measured hydrographs at the outlet of the basin. The model predicts the daily discharge values with a good accuracy, i.e. about 66% according to the Nash-Sutcliff criterion. Sensitivity and uncertainty analysis of the model parameters is performed using a model-independent parameter estimator, PEST. It is found that the correction factor for calculating the groundwater flow recession coefficient has the highest relative sensitivity and the parameters kss and kep located in two and three ranks of the relative sensitivity. Parameter uncertainty analysis shows that parameters ki; kep, kss and kg have high certainty and as well as parameters krain, kmax have low certainty.

The various types of land cover and land use have significant roles and impacts on runoff and flood; but how and to what extent is not clear and highly uncertain. The models are becoming more capable for flood prediction, landuse impacts on floods, and decision making in watershed management. The main objective of this research is to assess the impacts of land use changes on flow hydrograph by means of distributed modeling and GIS. A grid-based spatially distributed hydrologic model, WetSpa, which has been developed at the Department of Hydrology and Hydraulic Engineering of VUB, is used in this research to fulfill the aim. The basic model inputs are a digital elevation model (DEM), land use and soil maps of the study area in GIS raster format, and hydrometeorological data. The model is applied to the Dinvar river basin (1717 km2), and its main tributaries. The Dinvar river located in Kermanshah, is one of the main tributaries of the Karkheh River. The model predicts the daily hydrographs with a good accuracy, 66% according to the Nash-Sutcliffe. For assessing the impact of landuse changes on floods, the calibrated model is applied for nine scenarios using the hourly data. The potential of Dinvar cachment, nine landuse change scenarios in GIS was determined and entered the calibrated model for simulation. changes in processes and hydrological parameters were investigated by comparing the output hydrograph of present landuse with simulation result of 9 scenarios. Results show that model simulation is acceptable as for the result of model.