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This research studies empirical equation for abrasion of stilling basin caused by impact of the sediment.

Review of previous papers shows that in previous researches, the mixture effect of erosion and impact are

studied without determination of the share of impact in the mixture effect. Also in the researches, the sediment

grain size is not as large as debris size in debris flow or experiments are done without tail water

depth. Therefore, in this research, the impact of large grain size is studied on concrete stilling basin with

tail water. First dimensional analysis is carried out, and subsequently experimental plan is designed. The

experiment includes concrete samples with three different cement contents, five depths of tail water, three

grain sizes. Abrasion of each grain impact is measured and recorded. Uni-variable and multivariable

regression analyses were employed to find possible relation between abrasion ratio and the dimensionless

parameter of the experiment. The empirical equations are judged using mean absolute relative errors of the

equations. Then a multivariable power equation is proposed for determination of the impacts of abrasion

of sediment. The equation shows the abrasion is function of dimensionless energy of sediment grain and

the ratio of the grain velocity on stilling basin to the grain velocity on water surface.

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      Flood  has caused financial and vital damages in the  Hajighoshan watershed in recent decade.In this study, we investigated  the efficiency of flood control structures in decrease of flood hazard and their effects in the downstream flow regime.  First, a rainfall-runoff model has presented by using HEC-HMS model.The rainfall- runoff model was presented and optimized  by using 5  past flood events and then was validated with 4 another flood events.The dams were simulated by using Elevation-Area method  in the validated rainfall-runoff model. The results showed that The efficiency of flood control dams in decreasing of flood hazard dependents on their location, reservoir volume and  the surface of watershed or  sub-basin which it controlled its runoff.

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One of the effective ways to provide water in the arid, semi-arid and drought crisis is rising the groundwater stores. Underground dams are one of the best strategies for securing and development of water resources. The first and most important step in the construction of an underground dam is identifying suitable locations for the construction of these dams. Making decision about the site selection of the underground dam is difficult because several criteria must be considered in this choice. The purpose of this study is to select the underground dam site for storing precipitation and preventing evaporation in the Adori area in Bam city by using spatial multi-criteria evaluation (SMCE). The selected evaluation criteria include: (1) Economic and social criteria (including distance to aqueduct - distance to well - distance to village - distance to spring - distance to road - distance to rock source), (2) Hydrology (including precipitation isolines - rivers), (3) Geology (including topography (slope) - Geology - geomorphology - permeability), and (4) Constraints (including slope - fault - aqueduct – land use - geology - distance to river). The maps were first prepared in the ILWIS software, standardize with SMCE menu, and weighted by ranking method. Finally, the integrated map was prepared which shows three regions with different values. One of these three areas, which have the best value, was suggested for the construction of underground dam in the Adori area in Bam city.

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Global warming caused by emissions of carbon gases into the atmosphere is a serious threat to sustainable development in developing countries Such as Iran. Carbon sequestration in terrestrial ecosystem is a sustainable approach, with no environmental risks. This research was conducted to evaluate watershed management mechanical operations including water harvesting, terracing, sediment trapping dams, banquette and furrow in different regions of the country (nine provinces) in atmospheric carbon sequestration and to offer optimal options for these regions. For this purpose, field operations were done for soil, biomass and litter sampling, using systematic randomized method in representative sites and control sites. According to research results, regions in the hillsides of the Zagros mountains including Lorestan, Fars, Kermanshah and Kurdestan showed the maximum carbon sequestration potential in about 54 to 112 ton carbon per hectare. In Hirkani regions in Mazandaran province, water harvesting system operation sequestered about 18 ton carbons per hectare. Watershed management operation in center and west part of country with Iranotorani cover type cannot affect in soil organic carbon stock and rangeland biomass, significantly. In study areas, indigenous terracing and water harvesting systems have higher efficiency in carbon sequestration, respectively and different sediment trapping dams did not show significant effect in this case.

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    Sediment transport is one of the important indicators of rivers in natural conditions, which is affected by the change in geometric and flow characteristics, and is reflected in the alignment or sedimentation of different river routes. Therefore, providing suitable solutions for sediment control and fixing the longitudinal slope of the substrate and preventing sediment transport from upstream areas with a steep slope into the dams reservoirs, which is a major reason for their useful life, The necessity of carrying out the experiment in this field is justified. This research studies the sedimentation status and how it is controlled using the physical model of short successive dams made of Plexiglass at three altitudes and three different distances when the slope of the substrate and the discharge changes. Dimensional analysis was performed by Buckingham method to determine the variables such as depth ratio to height (y/H) and depth to distance (y/L) as effective factors in determining the percentage of cumulative sediment trapping (Teg). Accordingly, the relationship between the aforementioned ratios with the percentage of sediment trapping using dimension-less factor of Froude number as an independent variable in different scenarios has been investigated and evaluated Walls in the model, have been proposed for different slopes.

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Increasing population and consequently demand for water needs, food supplies are among the limitations that the current world faces. The existence of such a process with limited natural resources needs to improve the optimal and continuous exploitation of available resources. Watershed management is one of the suitable ways to meet nutritional needs and prevent economic consequences. It is important to be aware of the effectiveness of any type of project, including water management, for project executives. The economic evaluation of these activities is essential in order to know the ratio of profit to project costs. To this end, we have investigated and evaluated the economics of multifunctional plots and flood control in Khuzestan province.

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In recent decades, along with the development of the residential area, the problems of runoff and flood in urban watersheds have increased dramatically. Check dams have a direct and rapid effect on the flood. One of the most important elements of the construction of these structures is the identification of the suitable location for construction of the structure. This stage should be done with the utmost accuracy and precision due to the stability of the structure and the financial issues. In this study, the general approach is based on the fact that after identifying the area and collecting the required information, the factors influencing the construction of the structures were determined and the layers required for suitable location were prepared. After fuzzing the layers using Arc GIS 10.5 software, each layer is weighted according to the amount of its effect on site selection. Then, the layers combined using the fuzzy gamma operator and finally, after the field surveys, 22 optimal points and 3 completely optimal points for constructing the structures in the Ilam catchment area were identified. By construction of a check dams in the selected areas, it is possible to significantly reduce the damage to the facilities and waterlogging of the passageways.
 

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