Davood Nikkami; Samad Shadfar
Abstract
Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the ...
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Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the country, different figures have been mentioned and in some studies, the difference is with several times. These figures vary from less than one to more than five billion tons per year. Therefore, calculating and plotting erosion and sedimet yield maps provides important information that is used in the design of dams, reservoirs, canals, soil protection operations, onsite and offsite erosion damage assessment, and land use planning and land capability assessment projects. Soil erosion map is one of the basic, scientific and applied maps in various executive, research and educational sectors. Due to the need of determining the amount of soil erosion and sediment yield for the entire country and determining the executive priorities in areas with high soil erosion potential, this project was defined and carried out by the Soil Conservation and Watershed Management Research Institute. Accordingly, the watersheds of the seventh category were divided into seven regions or districts, including 1) Eastern Alborz 2) Middle Alborz 3) Western Alborz 4) Central Iran 5) North Zagros 6) Middle Zagros and 7) South Zagros. Long-term sedimen data of 118 hydrometric stations in these areas were analyzed and the amount of sediment in each station was determined by the logged mean load within discharge classes method. According to the amount of river bedload rates and using EPM model, the amount of sediment yield and cosidering sediment delivery ratio of watersheds, the amount of soil erosion were etermined and the soil erosion map of watersheds overlooking hydrometric stations was prepared. Results showed that the average sediment yield and soil erosion in the watersheds overlooking hydrometric stations are 3.3 and 16 tons per hectare per year, respectively. The lowest and highest soil erosion rates of 9 and 32.4 tons per hectare, belong to the Middle Zagros and South Zagros regions, respectively.
Sedigheh Mohamadi
Abstract
With regard to financial and technical problems normally measured sediment data are limited in developing countries; therefore a model that uses water discharge data as input can be a reliable option for estimates of sediment. Due to widely application of the variety of models to predict the suspended ...
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With regard to financial and technical problems normally measured sediment data are limited in developing countries; therefore a model that uses water discharge data as input can be a reliable option for estimates of sediment. Due to widely application of the variety of models to predict the suspended sediment, this study aims to determine optimal prediction model based on the amount of discharge flow gauging stations of Halilrood River including, Soltani, Henjan, Cheshmeh Aroos, Meydan and Konaruiyeh. In this regard, efficiency of some rating curves models including one-linear, two-linear and the intermediate categories ones (by and without coefficients as CF1, CF2 and FAO) and black box models including artificial neural networks and neural-fuzzy in modeling sediment were evaluated. The results of the evaluation of the model using the parameters of MAE and RMSE showed that neuro-fuzzy models in major hydrometric stations studied, including Pole Baft, Henjan and Konaruiyeh with an equivalent amounts of 35.07, 11958.74 and 34235.27 ton/day for MAE and 42.07, 28672.78 and 52735.92 ton/day for RMSE, respectively are the best models to simulate the suspended sediment. The artificial neural network model of radial basis function in Meydan with 384.83 ton/day MAE and 669 ton/day RMSE amounts is the optimal model. Also two-linear sediment rating curve resulted the best simulation in Cheshmeh Aroos Station with MAE and RMSE as 1.7 and 4.1 ton/day and one-linear sediment rating curve with CF1 correction in Soltani Station with MAE and RMSE 9723.2 and 41235.6 ton/day, respectively are the best. According to changes of efficiency of models with varying location of gauging stations, it can be concluded that ecological conditions and statistical community determine the optimal model of the suspended sediment simulation.
Mohammad Shabani
Abstract
Estimating instantaneous peak flow in watershed is one of the most important problems that cause hydrologists and experts to work seriously on it. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human ...
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Estimating instantaneous peak flow in watershed is one of the most important problems that cause hydrologists and experts to work seriously on it. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human brain to find the internal relation between data based on the training process. The objective of this study is to compare the efficiency of artificial neural network method and experimental methods for estimating instantaneous peak flow in Fars province watershed. For this purpose, 24 years of daily peak and instantaneous peak flow of seven hydrometric stations were considered and tested for outlier data. Then the estimation was done based on experimental methods including Fuller, Sangal and Fill-Steiner and artificial neural network method and were compared based on RMSE, MAE and R2. Results showed that estimation of artificial neural networks is more accurate than experimental methods in all stations which indicated the lower errors of artificial neural network method compared with experimental methods.
Haniyeh Asadi; Hamid Reza Moradi; Seyed Hamid Reza Sadeghi; Abdolrasoul Telvari
Abstract
The proper application of instantaneous unit hydrograph theory is very efficient for watershed with lack of rainfall data. Therefore, the present study has been conducted to evaluate the efficiency of Clark instantaneous unit hydrograph modelwith the help of geographical information system in regenerating ...
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The proper application of instantaneous unit hydrograph theory is very efficient for watershed with lack of rainfall data. Therefore, the present study has been conducted to evaluate the efficiency of Clark instantaneous unit hydrograph modelwith the help of geographical information system in regenerating flood unit hydrograph in Kasilian watershed in Mazandaran province. The comparative evaluation is conducted between the 3h-unit hydrographs simulated using Clark model and the one obtained from averaging the observed ones. This comparison is made with the help of statistical criteria viz. relative error, root mean square of error, coefficient of efficiency and bias. It verified high level of compatibility between two unit hydrographs using the Clark model and the hydrograph obtained by averaging the observed data.
Jafar Dastoorani; Ali Fazlollahi; Ali Salajeghe; Ghasem Dastoorani
Volume 2, Issue 3 , October 2010, , Pages 133-142
Abstract
Effective discharge (Qeff) that transports the most of suspended sediment in rivers and controls the bed conditions is an important criterion for evaluating the quality of water. Qeff usually has 1.5 years recurrence interval on the yearly maximum flood data series. For examining similarity between Qeff ...
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Effective discharge (Qeff) that transports the most of suspended sediment in rivers and controls the bed conditions is an important criterion for evaluating the quality of water. Qeff usually has 1.5 years recurrence interval on the yearly maximum flood data series. For examining similarity between Qeff and Q1.5 in ten stations of Daryacheh Namak Drainage Basin, at first the probability density function (pdf) of daily flows and sediment rating curves was plotted, after that probability density function of suspended sediment was constructed by multiplying the coefficient of sediment rating curves with pdf of daily flows. Then its recurrence interval was estimated by Vibul's method. The results showed that there are not any similarities between Qeff and Q1.5, and the ratio of Qeff to Q1.5 ranged from 1.03 to 16.8. Therefore more research is required to reach more certain result.
