Kaka Shahedi; mahtab forootan danesh
Abstract
Simulation of the rainfall-runoff process in a watershed is highly important from the point of view of hydrological issues, water resources management, river engineering, flood control structures and its storage. Rainfall-runoff estimation using a distributed hydrological model and the technique of GIS ...
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Simulation of the rainfall-runoff process in a watershed is highly important from the point of view of hydrological issues, water resources management, river engineering, flood control structures and its storage. Rainfall-runoff estimation using a distributed hydrological model and the technique of GIS has become possible, practical and common. The Wetspa model is a distributed model simulating runoff and water balance that is performed at different time scales including hourly or daily basis. In this research, the discharge is simulated using Wetspa model in the Ghorichay watershed. This watershed (as one of the sub-watersheds of Gorganrood) with an area of 2481.5 ha is located in the south of Ramian city in Golestan province. The data used by the model are land use maps, soil texture, digital elevation model, precipitation, evaporation, temperature and discharge (for calibration and validation of the model). Calibration of 13 parameters was performed manually and automatically for 7 years at the beginning of the statistical period and model validation was performed for a period of 5 years. The results of the model evaluation show the accuracy of discharge simulation and very good agreement between the simulated data and observations based on the Nash-Sutcliffe criterion of 67.21% in the calibration period and 76.34% in the validation period. Also, the discharge calculated by the Wetspa model for the whole watershed was 28.31%, which in comparison with the observed discharge of 30.12% indicates a good simulation of the model.
Kaka Shahedi; Haiyeh Asadi; Mohammad Golshan
Volume 3, Issue 7 , October 2016, , Pages 123-139
Abstract
Kaka Shahedi[1]* Haniyeh Asadi[2] Mohammad Gholshan[3] Abstract Estimation of runoff in ungauged catchments has been an important subject for experts in planning of various projects. Focus of this study was on comparison and evaluation of Clark’s model and time- area method in predicting output ...
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Kaka Shahedi[1]* Haniyeh Asadi[2] Mohammad Gholshan[3] Abstract Estimation of runoff in ungauged catchments has been an important subject for experts in planning of various projects. Focus of this study was on comparison and evaluation of Clark’s model and time- area method in predicting output hydrograph in watersheds with lack of basic data. To this end, the time-area histogram was drawn by ArcGIS and the topographic map. Then, using rain gauge data and time-area method, the output hydrograph was estimated. In the next step, the obtained results were compared with the observed output hydrograph. Afterwards the Clark instantaneous unit hydrograph was also estimated using storage coefficient in order to simulate the unit hydrograph in Kasilian watershed. The storage coefficient was estimated using graphical, Clark, Linsley, Mitchell, Johnstone-Cross, Eaton, Hoyt-Langbein, Nash, Carter, Morgan-Johnson and Bell methods. Results were compared using quantitative statistics of root mean square of error, bias in peak discharge, coefficient of efficiency, and relative errors in peak discharge, time to peak and base time. The comparison of results showed that graphical method has had the highest accuracy in estimation of storage coefficient. Also The comparison of results showed that the Clark’s model had a good efficiency rather than time-area method and this showed effect of storage coefficient in flood routing in Kasilian watershed. So this method can be used with more accuracy to estimate output hydrograph in watershed with lack of basic data. [1]- Associate Prof., Sari Agricultural Sciences and Natural Resources University, Sari, Iran, (Corresponding author), E-mail: kaka.shahedi@gmail.com. [2]- Ph.D Student, Sari Agricultural Sciences and Natural Resources University, Sari, Iran. [3]- Ph.D Student, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
