Lessons learned from 20 y of monitoring suburban development with distributed stormwater management in Clarksburg, Maryland, USA
Lessons learned from 20 y of monitoring suburban development with distributed stormwater management in Clarksburg, Maryland, USA
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美国马里兰州克拉克斯堡 20 年来通过分布式雨水管理监测郊区发展的经验教训
作者：
K. Hopkins;S. Woznicki;B. Williams;Charles C. Stillwell;Eric Naibert;M. Metes;Daniel K. Jones;D. Hogan;Natalie C. Hall;R. Fanelli;A. Bhaskar
城市发展是河流生态系统的一个众所周知的压力源，对负责减轻其影响的管理人员提出了挑战。对美国马里兰州蒙哥马利县5个流域的径流、水质、地貌和底栖生物群落进行了20年的监测。本研究综合了对研究区域监测工作的多项研究，并对最近的监测数据进行了新的分析，以记录从监测中吸取的主要教训。监测流域包括一个森林控制区，一个集中雨水管理的城市控制区，以及3个郊区处理流域，其特点是低影响开发和高密度的渗透集中雨水设施分布在整个流域。在开发前、施工期间和开发后对处理流域进行了监测。监测开始通知适应性管理的雨水和不透水的覆盖范围内的研究领域，重点是分布式雨水管理的影响。从我们的综合结果表明，分布式雨水管理是有利的集中式雨水管理相比，在许多方面。分布式雨水基础设施的水文效益更大，证明了减少径流量和峰值流量的能力，对于小风暴，复制开发前的条件。基流暂时增加施工阶段在处理流域。水质的好处是混合的，基流硝酸盐浓度下降，但有限的变化，硝酸盐出口和比电导增加后，发展。在处理流域，包括河岸带内的变化，尽管河岸缓冲区保护施工期间发生了重大的地形变化。生态监测表明，即使在某些情况下，生物完整性指数的分数反弹，敏感的底栖大型无脊椎动物的家庭没有完全恢复治疗流域。从这一综合中吸取的经验教训强调了跟踪河流健康的多个指标和考虑过去的土地使用的重要性，以及在流域分布更多的雨水设施是有益的，但不能减轻所有城市压力对水生生态系统的影响。
Urban development is a well-known stressor for stream ecosystems, presenting a challenge to managers tasked with mitigating its effects. For the past 20 y, streamflow, water quality, geomorphology, and benthic communities were monitored in 5 watersheds in Montgomery County, Maryland, USA. This study presents a synthesis of multiple studies of monitoring efforts in the study area and new analysis of more recent monitoring data to document the primary lessons learned from monitoring. The monitored watersheds include a forested control, an urban control with centralized stormwater management, and 3 suburban treatment watersheds featuring low-impact development and a high density of infiltration-focused stormwater facilities distributed across the watershed. Treatment watersheds were monitored before development, during construction, and after development. Monitoring was initiated to inform adaptive management of stormwater and impervious cover limits within the study area, with a focus on the impacts of distributed stormwater management. Results from our synthesis indicate that distributed stormwater management is advantageous compared with centralized stormwater management in numerous ways. Hydrologic benefits were greater with distributed stormwater infrastructure, demonstrating the ability to mitigate runoff volumes and peak flows and, for small storms, replicate predevelopment conditions. Baseflow temporarily increased during the construction phase in the treatment watersheds. Water-quality benefits were mixed, with declines in baseflow nitrate concentrations but limited changes to nitrate export and increases in specific conductance after development. Substantial topographic changes occurred during construction in the treatment watersheds, including changes within the riparian zone, despite riparian buffer protections. Ecological monitoring indicated that even though index of biotic integrity scores rebounded in some cases, sensitive benthic macroinvertebrate families did not fully recover in the treatment watersheds. Lessons learned from this synthesis highlight the importance of tracking multiple indicators of stream health and considering past land use and that more stormwater facilities distributed across the watershed is beneficial but cannot mitigate the effects of all urban stressors on aquatic ecosystems.