کنترل سیل

In the present study, a combination of delayed dams in the upstream basin with the coastal dike in the downstream of residential area of the Kan river was studied, so that for this combination, the cost of constructing the structures is minimized and the reduction of flood peak is maximized. For this purpose, multi-criteria decision method and TOPSIS method were used and the best option was determined. This research showed that for the best combination, if 3 delayed dams with coastal river dike are constructed, the peak of output flood reduce to 31.5%. In addition, the diffusion and elongation of the output hydrograph in the superior state were significant and the time of concentration of flood increase.

Due to increasing rate of flood risk throughout the world, including Iran, it is necessary to identify and prioritize flood-contributing areas for flood control activities. In this study, a new approach on Unit Flood Response method called “Flood Reduction method” was introduced which is applicable to prioritization of sub-basins for flood control activities. It was used to prioritize upstream sub-basins of Kardeh dam in Khorasan Razavi province. To conduct the study, the entire basin was divided into 24 sub-basins and physical characteristics of the basin and sub-basins were extracted using HEC-GeoHMS extension in ArcGIS. HEC-HMS model was calibrated using a rainfall-runoff event data and then, the 50-year design storm was simulated by this calibrated model. Prioritization of flood source areas was performed using the Unit Flood Response method and the Flood Reduction method was used to prioritize flood control activities. For the basin under study, the results showed that the sub-basin which has higher flood contribution is not necessarily the most appropriate sub-basins for flood control activities. In general, the prioritization results of the Flood Reduction method and those of the Unit Flood Response method were significantly different. The effect of rainfall duration on sub-basins prioritization was also studied. The results showed that rainfall duration has a significant effect on the sub-basins prioritization.

Design, analysis and operation of flood control systems are subjected to several uncertainties due to inherent behavior of flooding and random errors associated with measurements. One of these issues is, the design of levees that collaborated with hydrologic, hydraulic and economic uncertainties. In this paper, for the design of levees considering these uncertainties a stochastic optimization model based on Monte Carlo simulation has been developed. The resulted model is a nonlinear stochastic model that has been solved by LINGO-13 software. A reach in the Moali-abad river in the north of Shiraz city, has been considered as case study. Obtained results are compared with results of deterministic model. According to the results of the of model, a 20-year return period flood like deterministic model had highest annual net benefit and was selected as the design flood. Unlike the deterministic model, that every output (design parameters) is single valued, stochastic model gives a range for each parameter. Thus the statistical distributions of these parameters are also obtained.