Suma Mohamadpur; Hamed Rouhani; Hojat Ghorbani Vaghei; Seyed Morteza Seyedian; Abulhasan Fath Abadi
Abstract
In many semi-arid regions of Iran, soil erosion has turned into a serious environmental problem affecting land productivity, nutrient loss, water quality, and fresh water ecosystems. Rates of soil loss differ according to erosion type and land degradation processes. Rill erosion is commonly observed ...
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In many semi-arid regions of Iran, soil erosion has turned into a serious environmental problem affecting land productivity, nutrient loss, water quality, and fresh water ecosystems. Rates of soil loss differ according to erosion type and land degradation processes. Rill erosion is commonly observed when rainstorms occur on steep slopes and sediment transport in rill flows exhibits the characteristics of non-equilibrium transport. In this paper, sediment concentration of rill flow is estimated by adaptive neuro-fuzzy inference system (ANFIS). A series of mathematical equations and parameters affecting rill hydrodynamics and soil detachment were used for well-defined rill sediment concentration. A series of filed experiments were performed to evaluate the model. The stepwise method was used to select the most important and effective input variables from measured input parameters of soil properties, topographic and vegetation attributes affecting sediment concentration of rill flow. Based on the stepwise procedure, the most significant parameters in the model predications were steep slope, vegetation percentage, clay percentage, and shear stress parameters. The values of sediment concentration simulated by the model were in agreement with observed values with Coefficient of Correlation (R2), Root Mean Square Error (RMSE) and Mean Bias Error (MBE) of 0.697, 30.5 and 1.0, respectively. The results of the investigation shows that the data-driven ANFIS modeling approach can be a powerful alternative technique for correctly estimating rill sediment concentration.
Ali Golkarian
Abstract
Erosion is one of the important factors in soil degradation and decrease fertility and slope length is one of the most effective factors in land form and amount of erosion. The objective of this study was investigation of spatially variation of sediment concentration in slope length until to receive ...
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Erosion is one of the important factors in soil degradation and decrease fertility and slope length is one of the most effective factors in land form and amount of erosion. The objective of this study was investigation of spatially variation of sediment concentration in slope length until to receive transport capacity. To obtain this goal a hill slope simulator system designed and manufactured. This system include 10 flumes, each has five meter length which after series them become fifty meters. This system can produce cumulative flow via fifty watering can tube which are install on flumes with one meter interval and each flume discharging is 100 cc. Other variables include two type of soil and slope in three level 15, 22.5, 30 percent. Three replications were used for each treatment and totally 18 experiment was done. In each experiment four samples were gathered from end of each flume and concentration was determined. Complete randomized design with factorial arrangement was used for data analyzing. Richard’s function was used for fitting a suitable curve on observed data. Result was shown that effect of soil type on sediment concentration was not significant while slope and slope length effects was significant. Otherwise sediment concentration in the two last flumes was located in same class which is shown that sediment concentration achieved to transport capacity in this slope length. Also results were shown that Richard’s function can simulate trend of concentration variety in slope length.
