جستجوی مقالات مرتبط با کلیدواژه « SCS » در نشریات گروه « مهندسی آب »

The relationship between rainfall and runoff plays an important role in the hydrological studies of watershed. In this study, an attempt was made to use the dimensionless hydrograph, which was used in the basins with no statistical data, for a comparative watershed study in Dehbala. These models are as follows: Schneider unit hydrograph models, SCS and triangular model. Due to the unavailability of accurate statistics, a flood event was used in Dehbala. The comparison of three methods of synthetic unit hydrograph with the natural one was indicative of the better coordination of the Schneider procedure for estimation of the observed hydrograph. Moreover, the highest peak of the lowest motion error is related to the SCS method. Among those methods, unit hydrograph needs the least amount of time to reach peak flow error is observed in Schneider method and the maximum error in time is related to the triangular method. The least degree of conformity is observed in the triangular and SCS methods However, Schneider is in good agreement with the observed hydrograph.

In recent years, many empirical methods and mathematical models have been developed to estimate runoff, among which the SCS curve number is the most important and widely used method. In this method a parameter called Curve Number (CN) is used for transforming rainfall to runoff. Currently, different techniques such as RS and GIS in combination with filed surveying are used to estimate this parameter. These methods due to the huge amount of required data, field investigation, and computation burden are costly and time consuming. In this research based on the saturation excess concept, which is used in the structure of a semi distributed model called TOPMODEL, a new efficient method with a minimum data requirement was developed to estimate the SCS curve number. The proposed method depends on three parameters: soil porosity, average distance to the catchment water table, and the parameter that controls the effective depth of the saturated soil. The Kasilian catchment in northern Iran is used to investigate the proposed method. In this study, using lansat7 ETM+ images and performing some modification on the images the landuse map was obtained. Finally, by combining this map and the watershed soil and slope maps and also the results of an extensive filed survey, the SCS curve number map was developed for the entire watershed. Also, TOPMODEL was calibrated in the Kasilian catchment for the estimation of proposed method parameters. Results indicate that the watershed's average curve number based on RS/GIS and the proposed methods are about 59.6 and 62.8, respectively. Furthermore, the results showed that the minimum and maximum differences between the Curve Number obtained from RS and GIS techniques and from the proposed method for the whole range of the used parameters are about 0.3% and 12% respectively.

Lakes Haft barm are series of freshwater lakes which are located in the North West in the East folded Zagros. These lakes are located in the interior Fars on Gachsaran formation and western margin of Karebas fault. In this research, in order to identify water source of lakes Haftbarm, a comprehensive study including field observations, chemical and isotopic analysis and measurement of Input and output was performed and the change in water level of the lakes were investigated. Preliminary studies reveal that three distinct aquifers could be distinguished based on hydrogeological and hydro chemical characteristics of the study area. Three aquifers, namely limestone aquifer, alluvial aquifer and Gachsaran formation aquifer were identified. Potentially, lakes Haftbarm could be recharged by these aquifers. The results showed that the main source of water in lakes Haftbarm in surface water. Using evidence obtained from geological, hydrogeological, hydrochemical and isotopic data, it can be concluded that the main source of the lakes Haftbarm water is surface water around the lakes.