The wider benefits of natural flood management are increasingly used to engage local stakeholders and justify physical implementation. Previous studies have highlighted the potential for upstream natural flood management interventions to contribute to water level management strategies by mitigating downstream water levels and promoting free discharge at surface drainage outfalls from urban areas. The study reported in this paper extended the scope of this possible benefit by examining the potential for upstream interventions to de-synchronise rural and urban responses under various storm tracks, thereby improving the performance of downstream surface drainage networks. The methodology used a coupled modelling approach. Five design events, each applied with eight different storm tracks, were used to evaluate how catchment-scale natural flood management in the upper Calder River, UK, might influence performance of surface drainage in the downstream town of Todmorden. The results suggested that all the storm tracks considered had substantial influence on whether urban rainfall occurs during the period when outfalls are inundated. While upstream natural flood management interventions create modest flow attenuation, a slight delay in rural response can significantly improve drainage performance and reduce instances of nuisance flooding.

中文翻译：

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自然洪水管理如何帮助不同风暴方向的下游城市排水

自然洪水管理的更广泛好处越来越多地用于吸引当地利益相关者并证明实际实施的合理性。先前的研究强调了上游自然洪水管理干预措施通过降低下游水位和促进城市地区地表排水口的自由排放来促进水位管理战略的潜力。本文报告的研究通过检查上游干预措施在各种风暴路径下使农村和城市响应不同步的潜力，从而提高了下游地表排水网络的性能，从而扩展了这种可能的好处的范围。该方法使用耦合建模方法。五个设计事件，每个事件都应用了八个不同的风暴轨迹，用于评估英国卡尔德河上游集水区规模的自然洪水管理如何影响下游托德莫登镇的地表排水性能。结果表明，所有考虑的风暴路径都对排污口淹没期间是否发生城市降雨产生重大影响。虽然上游自然洪水管理干预措施造成适度的流量衰减，但农村响应的轻微延迟可以显着提高排水性能并减少滋扰性洪水的实例。