The application of LIDs in Savanna region for mitigation of flooded areas

ABSTRACT The increase in runoff volume due to urban sprawl has imposed a challenge to current urban drainage systems and future projects in order to add sustainable strategies for effective flood control especially in consolidated urban areas that would require retrofitting of urban areas with additional social and economic costs. This study is aimed at evaluating alternatives of drainage solutions in a consolidated urban area in the Federal District of Brazil, located in Savanna region, based on the reduction of peak flow and flooded volume in the areas exposed to flood hazard. Different solutions based on the concepts of Low Impact Development (LID) were simulated, showing that the current traditional drainage system is not in compliance with local regulations in the Federal District. In addition, the use of permeable pavements and stormwater ponds could reduce at least 46% of the flooded volume. When placed along with the drainage network, not only at the outlet, stormwater ponds were able to reduce the flooded volume and its hazard and damages. However, LIDs solutions were not able to completely eliminate floods in the region. Structural changes, as resizing the conduits into the drainage systems in the area, could improve the drainage system effectiveness avoiding floods and respective hazards and damages.

摘要
城市扩张引发径流量攀升，给既有城市排水系统与未来工程带来严峻挑战，亟需引入可持续策略以实现高效防洪，尤其针对建成城区——此类区域的改造需承担额外的社会与经济成本。
本研究以巴西联邦区萨瓦纳（Savanna）区域某建成城区为研究对象，以降低洪涝风险区域的峰值流量与积水体积为目标，对多种排水解决方案的备选策略开展评估。研究模拟了多款基于低影响开发（Low Impact Development, LID）理念的方案，结果表明当前传统排水系统无法契合巴西联邦区的地方规范要求。此外，采用透水铺装与雨水塘可至少削减46%的积水体积。若将雨水塘布设至排水管网沿线而非仅设于出水口处，不仅可降低积水体积，还能缓解洪涝灾害并减少相关损失。不过，低影响开发方案无法完全消除该区域的洪涝灾害。对该区域排水系统的管道进行尺寸调整等结构性改造，可提升排水系统整体效能，从而规避洪涝及其引发的灾害与损失。