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

Increasing encroachment on rivers along with climate change has increased major floods. Levees are considered the most important structures to protect river banks and floodplains from flooding due to their simplicity of structure, inexpensive materials, and ease of implementation. In this research, an attempt was made to introduce a new approach in geometric modeling, to develop mathematical relationships to calculate the volumes of levees based on different location of each scenario in the floodplain. Study scenarios supply the protection of three kilometers of the Chabahar-Zahedan arterial road and its widening, which is located in the floodplain of the Karvandar River in southeastern Iran. Hydraulic simulations implemented in HEC-RAS for the existing condition and 13 different scenarios with 13 unique topographies based on the new approach, and the rate of reduction of the flood zone and embankment volume of levees for each scenario calculated in ArcMap. Based on the results, changes in the volume of embankments in different scenarios did not correlate well with the flood zone area reduction. Due to the direct dependence of scouring and thus geometry and volumes of levees on flow velocity, by calculating the flow maximum velocity in the study interval, the dimensionless coefficients of maximum velocity in different scenarios were calculated and applied to the calculated volumes of levees. Thus, by this approach and using quadratic polynomial equations, the coefficient of determination (R2) increased from 0.35, 0.48 and 0.50 to acceptable values ​​of 0.88, 0.91 and 0.92, for floods with return periods of 50, 100 and 200 years, respectively, which indicate the high efficiency of the proposed approach and also increasing in R2 values with an increase in the flood return period. Moreover, results show that the computational accuracy of regression relationships in the scenarios with levee locations in the middle distances from the road axis is higher than other scenarios which are closer or farther. This result is due to more irregular river geometry in the scenarios closer to the road and the intensification of nonlinear changes in flood parameters in the farther scenarios.

The present study is aimed to optimum design the one of the structural methods of flood control (Levees) based on dynamic programming (DP). In order to accelerate computing time, a model was created based on the combination of discrete differential dynamic programming and genetic algorithm (GA-DDDP). The objective function of this model is to minimize the total costs, including the cost of constructing the structure and residual damage cost. For this purpose, the length of the studied river was divided into three reaches and the optimal dimensions of the four sections were obtained as output results. Modeling and running was done by coding in MATLAB software and the results showed that the running time of GA-DDDP combined model is just 11% of the time to running the classic dynamic planning model. Also in this study, the results of the four-section model were compared with the simpler single-section model (equivalent section). The results show that the simplification of model to one section causes the increasing costs to about 20%.