جستجوی مقالات مرتبط با کلیدواژه « برآورد رسوب » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Estimation of the amount of sediment material (carried by a specific stream) is one of the main topics of sediment research. Sediment research is important in many engineering projects such as planning and design of water storage resources, morphology and changes in river bed, annual sediment estimation for reservoirs, sustainable irrigation, coastal protection, channel dredging, and etc.The evaluation of the sediment occurrences, and estimation of the sediment carried by rivers has a special importance and it is necessary to develop new methods with easy application for estimating the sediment transport. This study seeks to develop a method to be able to predict the amount of bedload with classification and regression trees and compare with some well-known empirical formulas such as Meyer Petter Muller, Shields, Einstein Brown, and Shoklitch. Measured data from Yazdakan station, located in Qotour River in Azarbayjan Gharbi, northwest of Iran, has been used in this research. It is a mountainous river with gravel bed that carries a high volume of sedimentation. A set of 76 field measurements over 8 years was used in modeling after verification and refinement. The model was trained on 80 percent of data and tested on the remained 20 percent. The best input contained whole four variables; flow discharge, suspended sediment discharge, flow depth and velocity, and the output was bedload discharge. The quantitative results of the best Decision Tree include MAE = 2134, RMSE = 2668 and % R = 89. The results of Regression Trees demonstrate more accuracy in the prediction of bedload compared with empirical formulas.

Water and soil are the most important natural resources of each country and are the foundation of human life. Soil erosion and sediment production causes reduced fertility of arable land and therefore are threatening human life On the other hand, increasing sedimentation amount in watersheds has an important role in reducing useful life of dams and dewatering reducing capacity of them. Thus the study of soil erosion and the estimation of the output sediment watershed are necessary. Researches carrying out the quantitative assessment of sediment production using the different models are one of solutions that through which one can partly control and minimize the amount of this phenomenon. The aim of this research is to evaluate efficiency of the WEPP model in estimation the output sediment Sulachai watershed. The method in WEPP model this is that, to the beginning the file related to each of the model parameters such as climate, soil, topography, management and drainage is created and entered on the software GeoWEPP and finally sediment load is calculated. WEPP model has required performance in sediment estimation for the three-scale slope, catchment area and flow-direction. Estimated sediment by each of the above three scales, is 0.213, 0.178 and 0.785 respectively, and for observed sediment is about 0.241 ton/hectares/year. The results of the comparison of WEPP model with the observed sediment indicated that from among the scales available in the WEPP model, slope and catchment area scales were closer to the amount of sediment observed and have offered more acceptable results than the flow-direction scale.