Maryam Daemi; Amirreza Keshtkar; Saeed Bazgeir; Ali Afzali; Omid Kavoosi
Abstract
Hydrological drought is used to show the reduction of surface flows and the drop in the level of underground water reservoirs, lakes, and rivers. The present research was carried out to determine the basic flow index values and to check its efficiency in determining the type of flow regime and regional ...
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Hydrological drought is used to show the reduction of surface flows and the drop in the level of underground water reservoirs, lakes, and rivers. The present research was carried out to determine the basic flow index values and to check its efficiency in determining the type of flow regime and regional analysis of hydrological drought in the Halil-Rood watershed. For this purpose, three homogeneous hydrological drought zones were determined based on the threshold level and cluster analysis, and then the base flow index was calculated on a daily scale using the daily discharge data in 10 hydrometric stations in the homogeneous zones. The results showed that the regional average of the annual base flow index is 0.38 with a standard deviation of 0.193 in the long-term statistical period and the range of the base flow index is 0.12-0.29. Based on the 70th, 80th, and 90th percentiles, the river flow regime was divided into four classes, and it was found that 100% of the watershed sub-basins of the study area had an unstable regime. Also, the results of drought zoning showed that hydrological drought occurred at the threshold level of 70 in the southeast of the region in the area of the Dehroud hydrometric station and in the levels of 80 and 90 in the northwest of the region in the area of Baft and Cheshme-Arus stations. The results of the present research can be used in the assessment of underground water supply, water supply systems, irrigation management, hydrological drought monitoring, and regional models in the estimation of water resource reserves in areas without statistics.
Omid Kavoosi; Khaled Ahmadaali; Aliakbar Nazari Samani
Abstract
Soil erosion and its consequences, such as soil destruction at the source, silting of rivers and filling of reservoirs of dams, are one of the most important natural hazards in watersheds, which reduce ecosystem durability. To be one of the most important practical solutions to control sedimentation ...
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Soil erosion and its consequences, such as soil destruction at the source, silting of rivers and filling of reservoirs of dams, are one of the most important natural hazards in watersheds, which reduce ecosystem durability. To be one of the most important practical solutions to control sedimentation and reduce peak flow is to build a check dam. Therefore, determining the quantitative variables affecting the volume of the structure is an important factor in determining the construction costs and their effectiveness. The present study was conducted to model checkdam volumes at the level of 100 sub-basins in different provinces of Iran (Alborz, East Azerbaijan, Ilam, Isfahan, Bushehr, Tehran, Qazvin, Fars, Mazandaran, and Hamadan). The database used for modeling includes 27 environmental features extracted in each of 100 sub-basins and the modeling was done using Genetic Expression Algorithm (GEP). The results of modeling showed that the most important characteristics in estimating the volume of checkdam among the 27 characteristics are: precipitation, temperature, TWI index, shape factor, height difference, concentration time, slope, drainage density and NDVI index. The results of estimating the volume of the structures using the nine selected variables showed that the R2, RRMSE and NSE values for the training phase are .088, .035 and 0.92, respectively, and for the test phase, they are 0.91, 0.29 and 0.91, respectively. Also, based on the results, the characteristics of environmental precipitation can be used with great accuracy to estimate the volume of sediment control structures in a short time, and therefore, before their implementation, the related costs were known in order to prioritize the areas.
