بررسي رويكردهاي جايگزين با تأثيرات جانبي كمتر در مديريت سيلاب‌هاي شهر اصفهان بزرگ

Urban development and the increase in construction have led to a change in the surface cover of cities. The increase in impervious surfaces, such as roofs and streets, prevents rainwater from infiltrating into the soil, resulting in a significant portion of rainfall being converted to surface runoff. This has led to an increase in urban runoff, which in turn exacerbates flooding and street flooding. To address the problem of urban flooding, new approaches that consider sustainable stormwater management are being considered as a replacement for the collection and discharge of stormwater. In this regard, several strategies, known as low-impact development (LID) methods, which are maximally compatible with the natural water cycle processes, have been considered. These methods are generally implemented in small-scale units (small facilities) that provide many benefits, including reduced runoff volume, groundwater recharge, improved runoff quality, biodiversity support, urban landscape beautification, and more. In this study, the application and performance of LID in flood management in District 4 of Isfahan was investigated. The analysis and design of the stormwater drainage network was performed using accurate and up-to-date information using the SWMM software. The simulation results were eva‎luated comparatively using the results of similar software, including HEC-HMS. The impact of 5 LID methods, including bioretention, vegetated soil (using the absorption capacity of materials), permeable pavement, infiltration trench, and infiltration well, individually and in combination, on the control of runoff discharge and volume was investigated in a practical and implementable way in accordance with the capacity of the region. In order to be aware of the economic effects of LID methods, their implementation costs were calculated and compared. The results of the present study show that LID methods can reduce the peak runoff discharge at outlet points by up to 40%, reduce the volume of flooding in sub-basins by up to 34%, and reduce the dimensions of channels. However, the implementation of LID has not actually resulted in a reduction in stormwater management costs. The results of the present study show that for better effectiveness of LID methods, the use of a combination of them brings better results and plays a more effective role in urban development. In the use of LID methods, one should not be solely in search of economic benefit. LID methods are environmentally friendly, and they take into account compatibility with the natural landscape and the development of natural green spaces, and instead reduce deep excavations and large dimensions of concrete channels. Water infiltration, aquifer strengthening, runoff pollution reduction, and risk reduction are the undeniable benefits of using these new urban flood management methods. Low-impact development methods have challenges such as high initial implementation costs and the need for careful design. By optimal application and overcoming these challenges, the value of this management approach for urban flood management increases.

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علي طالبي

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