Estimation of erosion and sediment yield using WEPP model in Sharif Abad Watershed of Birjand

Gholamzade, M. R. (2012) Estimation of erosion and sediment yield using WEPP model in Sharif Abad Watershed of Birjand. Masters thesis, University of Zabol.

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Finding a suitable model to study erosion and sedimentation processes in a specific area have been a major concern for researchers. This research was conducted in the Sharif Abad watershed, to estimate total sediment yield using WEPP model. To run the WEPP model, five data files were entered into the model; including: Soil, Management, Topography, Channel and Climate file. In the soil data file a variety of information such as; clay, sand and organic matter percentage, coefficient of soil action exchange, rill and inter-rill readabilities, critical shear stress, albedo and effective hydraulic conductivity were measured. In the management file land use type, management practices and measures, vegetation cover attributes and physiological and phenological characteristics of dominant plants were interred. To create management file the CPIDS database was used. To import information of the topographic file into the model, a ١٠-m Digital Elevation Model was used. To create a climate file, the Cligen software was used. To prepare the climate file daily temperature and precipitation data were used. The instructions of model user guide were used to build the canal files. There were ٥ types of streams, ٢٣ units of Soil and ٧٥ units of management in the study area. However, following the data preparation the WEPP Watershed and Hill slope model was run using GeoWepp to estimate sediment yield of the study watersheds and the results were assessed to compare the Watershed and Hill slope version results together as well as with measured values. Also, in the Sharif Abad watershed the sedimentation rate in three Watershed, Hill slope and Flow path method were compared with the observed rate. The estimated sedimentation rate of Hill slope, Watershed and Flow path method was ٣.١٧, ٤.١٥ and ١.٣٦ t/ha. yr, respectively, while the observation was measured at ٢.٨٥ t/ha. yr. The Sharif Abad watershed was divided into two sub-watersheds, and the model was run for both watersheds. To test whether the data distributed normally, the Kolmogroff - Smirnov test was used. also to compare means of the data, the independent t- test at ٠.٠٥ significant level was used and there was no significant difference between the mean of estimated sediment yield and the mean of observed values in the both Watershed and Hill slope, but the mean of estimated sediment yield and the mean of observed values in the Flow path method was significant difference. Then work other indices were calculated for both Hill slope and watershed basin method To compare the results of the two methods as well as with the observation values, the Nash-Sutcliff coefficient and the coefficient of determination were used. The Nash-Sutcliff coefficient and the coefficient of determination for Hill slope method calculated at ٠.٩٥ and ٠.٩٦, and they were ٠.٧٤ and ٠.٧٥ for the Watershed method, respectively. According to the different efficiency criteria that were used in this study, it was found that the Hill slope methods has better performance than the Watershed approach to estimate soil erosion and sediment yield in this study area. However, the model over-estimated sediment yield but since there was not a significant differences between the observed and the estimated values, the model can be recommended to the area which have the same geographical and environmental characteristics as Sharif Abad watershed does.

Item Type: Thesis (Masters)
Uncontrolled Keywords: WEPP Model, Erosion and Sediment, Sharif Abad Watershed, Geowepp Software
Subjects: S Agriculture > S Agriculture (General)
Depositing User: admin admin1 admin2
Date Deposited: 19 Jun 2016 04:41
Last Modified: 19 Jun 2016 04:41

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