Reza Talaei; Mohsen Shariat Jafarei; Bayramali Beyrami
Abstract
Landslides are the major causes of erosion and sediment yield in the sloping and mountainous basins. However, evidence suggests that the amount of sediment to the river of the mountainous regions in Ardabil province due to landslides is significant, but in quantitative terms it has not been provided ...
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Landslides are the major causes of erosion and sediment yield in the sloping and mountainous basins. However, evidence suggests that the amount of sediment to the river of the mountainous regions in Ardabil province due to landslides is significant, but in quantitative terms it has not been provided the certain value based on scientific research for it. In this study, the subject was evaluated in the Balekhlou-Chay catchment of Ardabil province using data extracted from the aerial photographs, field investigations and the sediment discharge measured data at Pole-Almas hydrometric station. Sediment volume in the sediment measurement stations associated with the catchment was estimated by determining the relationship between flow rate and it′s corresponding sediment discharge. It was attempted to compare the estimated amount of sediment at different time periods with its amount in the periods of activity of landslides and to determine the possible effects of the landslides in increasing erosion and sediment yield in the catchment. The noted large landslides have caused a significant increase in the sediment load of the available rivers. The effects of these slides can be observed in the suspended load passing through Pol-e-Almas station. The mean of the suspended sediment concentration of Balekhlou-Chay catchment has been estimated about 46566.30 tons per year based on sediment discharge values from field data during 40 years (from 1972 to 2001), however the mean of the suspended sediment concentration is 30831 tons per year based on sediment discharge values from field data during 36 years, which means with the elimination of the data related to landslide years (from 1980 to 1983). In conclusion, according to the calculated sediment carried by the Balekhlou-Chay river after the occurrence of the Sarighaye and Ilanjigh landslides during the period of 4 years (from 1980 to 1983) has been increased rapidly.
Seyed Ali Asghar Hashemi; Mahmood Arabkhedri
Volume 2, Issue 1 , May 2010, , Pages 25-34
Abstract
Evaluation of empirical models for sediment yield in watersheds is a necessity. One of the conventional models in Iran is MPSIAC that has been used extensively. Sediment measurement of small dam's reservoirs is one of the methods for evaluation of these models. In this research, 9 small watersheds were ...
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Evaluation of empirical models for sediment yield in watersheds is a necessity. One of the conventional models in Iran is MPSIAC that has been used extensively. Sediment measurement of small dam's reservoirs is one of the methods for evaluation of these models. In this research, 9 small watersheds were selected in Semnan Province. There is an earth small dam at the outlet of each watershed built in the past 10 years. These dams have not spilled since they were built. Therefore total sediment volume discharged from each watershed was entrapped behind the dams. The amount of deposited sediments in these reservoirs was measured by surveying and estimation of apparent Specific Weight which then compared with estimating values of MPSIAC model by paired t-test. The results showed that the difference between the means for estimated volumes of sediment yield by use of MPSIAC model at the level of 5% had no significant difference while the difference between mean weights of sediments at the level of 5% was significant. Also determination of performance and relative root mean square error showed that MPSIAC model has no appropriate efficiency for application in the region.
