جستجوی مقالات مرتبط با کلیدواژه « روش SCS » در نشریات گروه « آب و خاک »

In the design of engineering structures such as overflows, sewers, flood control plans and water resources management, there is a need to obtain the maximum flood flow. Despite the statistical deficiencies and the absence of hydrometric stations in most of the small areas, choosing the appropriate methods according to the specific conditions of each area becomes very important. The current research, which has been carried out, examines several experimental methods of flood discharge estimation. Among the methods used in this research, we can mention Fuller, Krieger, Deacon and other methods based on the domain level. The results of the research show that the SCS method has the ability to significantly improve the accuracy and estimation of the flood discharge by taking into account the temporal and spatial characteristics. This progress in research has not only improved the understanding of flood behavior in the studied basins, but also seems to be a powerful tool for flood hydrograph analysis and accurate estimation of flood discharge in basins. Therefore, the results of the research will not only play a fundamental role in improving the understanding of water resources, but also have great importance in maintaining the stability of aquifers. In general, the results of this research have not only improved the understanding of flood behavior in the studied basins, but also show It is the fact that the use of SCS method can provide us with the analysis of the flood hydrograph and the accurate estimation of the flood discharge of the basins.

The Curve Number (SCS-CN) method, one of the most widely used methods for estimating runoff in hydrology, has been developed by soil conservation services. The application of SCS equation in Iran may be mixed with considerable errors due to different climatological, geological, and hydrological characteristics.  In addition, the other cause of error in this method is the relationship between Ia and S (Equation 2), which is experimental and has been taken from rainwater data in small laboratories (Anonymous, 1972). This relationship can be criticized in terms of the document and was examined in various studies of its accuracy and application (Bo et al., 2011, Shi et al., 2009, Baltas et al., 2007, Mishra et al ., 2006,2004, Hawkins et al., 2002), In order to calibrate the SCS equation and evaluation in empirical relations, Pasekohak catchment was selected. Pasekohak basin includes four sub-basins where flood runoff was gauged during five flood events. Curve Number (CN) for the sub-basins was estimated according to the remote sensing, geological maps, and field works. The real hydrograph for each event was compared with SCS hydrograph in HEC-HMS software, and the calibration and correction of SCS coefficients were conducted. The results suggest a correction coefficient of 0.92 for SCSLag, the average ratio of Ia/S is 0.044, which is completely different from 0.2 in SCS. The CN in the study area is 0.41 of CN provided by SCS.

The SCS-CN developed by the USDA Soil Conservation Service is a widely used technique for estimation of direct runoff from rainfall events. The watershed CN represents the hydrological response of watershed as an indicator of watershed potential runoff generation. The aim of this research is determining the CN from recorded rainfall-runoff events in different seasons and analyzing its relationship with rainfall components in the Jafarabad Watershed, Golestan Province. The CN values of 43 simultaneous storm events were determined using SCS-CN model and the available storm events of each season have been separated and the significant differences of CN values were analyzed using ANOVA method. The Triple Diagram Models provided by Surfer software were used to analyze the relationships of CNs and rainfall components. Results showed that the mean values of CN were 60 for summer and winter seasons and the CN values in the spring and autumn seasons were 50 and 65, respectively. The inter-relationships of CN amounts and rainfall characteristic showed that the high values of CNs were related to high rainfall intensities (>10 mm/hr) and rain-storms with total rainfall more than 40 mm. Also the CN values were about >70 for the storm events with 40-80% runoff coefficient values.

Low application efficiency is the main problem of surface irrigation systems. In order to compare and improve furrow irrigation design methods including FAO, SCS, volume balance, kinematic wave and zero-inertia methods, field experiments were conducted for measuring design parameters of furrow irrigation. Results showed that the volume balance method gave the most accurate results of infiltration equation. Also attributing an intake family of the SCS method for field data caused error in the computation. Adjustment of SCS advance time equation and volume balance methods increased the model accuracy. With improvement ofSCS advance time, the residual mass coefficient (CRM) and root mean square error (RMSE) of advance time changed from -0.4 to -0.019 and from 10.36 to 2.34 min, respectively. Improving volume balance method, using surface and subsurface storages and modified Kostiakov-lewis infiltration equation, decreased the RMSE and CRM advance time from 8 to 6.26 min and from 0.32 to 0.25, respectively. Results showed that short time steps and more iteration should be performing for less error in the improved volume balance method. Created contours by WinSRFR4.1 model allow user to search a set of variables by consideration of hydraulic and practical conditions to achieve high level of uniformity and efficiency at zero-inertia and kinematic wave models.

As unit hydrograph is an important item in flood estimation of the rivers and since flood hydrograph and simultaneous rainfall hyetograph is needed to derive a unit hydrograph, hydrologists recommend synthetic unit hydrographs for areas lacking these hydrometeorological data. A research was conducted in the Zayandehrud-dam watershed (Pelasjan sub-basin) to test the efficiency of synthetic unit hydrographs (Snyder, SCS, and Triangular methods) in hydrological evaluations. For the purposes of this study, natural and synthetic unit hydrographs were determined and compared, using all morphologic, hydrometric and rainfall data. The results showed that Triangular and SCS methods fit natural unit hydrographs better than Snyder method does, but peak instantaneous flow is estimated to be higher than the observed flow. So, the constant 2.083 in peak flow equation is recommended to be changed to 1.74 in this watershed. The Snyder method predicts good peak flows, compared with the other two methods. Generally, it is concluded that Triangular, SCS, and Snyder methods are ranked 1 to 3 for determination of synthetic unit hydrographs in this watershed.