Towsif Khan S, Wynn-Thompson T, Sample D
Water Resources Engineer, Center for Watershed Protection, Fulton, MD, USA.
Biological Systems Engineering, Virginia Tech, Blacksburg, VA, USA.
J Environ Manage. 2025 Feb;374:123651. doi: 10.1016/j.jenvman.2024.123651. Epub 2025 Jan 12.
The hydrologic benefits of catchment-scale implementation of stormwater control measures (SCMs) in mitigating the adverse effects of urbanization are well established. Nevertheless, recent studies indicate that the Unified Stormwater Sizing Criteria (USSC) regulations, mandating the combined use of distributed and storage stormwater controls, do not protect channel stability, despite their effectiveness in reducing runoff from impervious surfaces. The USSC are the basis of SCM design in 11 U.S. states and the District of Columbia. This study employed a calibrated, sequential modeling approach, which integrated a catchment-scale Storm Water Management Model (SWMM) with the Hydrologic Engineering Center River Analysis System (HEC-RAS), to evaluate the effectiveness of two alternative stormwater regulations in preventing channel erosion. A three-step methodology was developed using the calibrated SWMM and HEC-RAS models: (1) establish the pre-development scenario; (2) design SCMs for channel stability under design storm conditions; and, (3) assess regulation effectiveness through continuous simulations. The modeling results revealed that designing stormwater controls using the USSC increased sediment transport for the 1-, 2-, and 5-yr, 24-hr annual recurrence interval (ARI) design storms 2 to 2.7 times the pre-development conditions. SCM designs aimed at matching the sediment transport of the pre-development catchment reduced peak flows 30-70% and prevented knickpoint formation, as compared to designs based on hydrologic targets only. Study results demonstrate that to protect channels from degradation following urban development, the morphology and bed material of the receiving channel must be considered in the design of stormwater controls.
在缓解城市化负面影响方面，集水区尺度实施雨水控制措施（SCMs）的水文效益已得到充分证实。然而，最近的研究表明，统一雨水规模标准（USSC）规定要求同时使用分布式和存储式雨水控制措施，尽管它们在减少不透水表面径流方面有效，但并不能保护河道稳定性。USSC是美国11个州和哥伦比亚特区SCM设计的基础。本研究采用了一种经过校准的顺序建模方法，将集水区尺度的雨水管理模型（SWMM）与水文工程中心河流分析系统（HEC-RAS）相结合，以评估两种替代雨水法规在防止河道侵蚀方面的有效性。利用校准后的SWMM和HEC-RAS模型开发了一种三步方法：（1）建立开发前的情景；（2）在设计暴雨条件下设计用于河道稳定性的SCMs；（3）通过连续模拟评估法规的有效性。建模结果表明，使用USSC设计雨水控制措施会使1年、2年和5年、24小时年重现期（ARI）设计暴雨的泥沙输移量比开发前条件增加2至2.7倍。与仅基于水文目标的设计相比，旨在匹配开发前集水区泥沙输移量的SCM设计使峰值流量降低了30%-70%，并防止了节点形成。研究结果表明，为了保护城市发展后的河道不退化，在雨水控制措施设计中必须考虑受纳河道的形态和河床材料。
