Hopkins Kristina G, Loperfido J V, Craig Laura S, Noe Gregory B, Hogan Dianna M
U.S. Geological Survey, Eastern Geographic Science Center, 521 National Center, Reston, VA, USA.
McAdams Company, 2905 Meridian Parkway, Durham, NC, USA.
J Environ Manage. 2017 Dec 1;203(Pt 1):286-298. doi: 10.1016/j.jenvman.2017.07.067. Epub 2017 Aug 10.
Stormwater control measures (SCMs) are used to retain stormwater and pollutants. SCMs have traditionally been installed in a centralized manner using detention to mitigate peak flows. Recently, distributed SCM networks that treat runoff near the source have been increasingly utilized. The aim of this study was to evaluate differences among watersheds that vary in SCM arrangement by assessing differences in baseflow nutrient (NO-N and PO) concentrations and fluxes, stormflow export of suspended sediments and particulate phosphorus (PP), and runoff characteristics. A paired watershed approach was used to compare export between 2004 and 2016 from one forested watershed (For-MD), one suburban watershed with centralized SCMs (Cent-MD), and one suburban watershed with distributed SCMs (Dist-MD). Results indicated baseflow nitrate (NO-N) concentrations typically exceeded 1 mg-N/L in all watersheds and were highest in Dist-MD. Over the last 10 years in Dist-MD, nitrate concentrations in both stream baseflow and in a groundwater well declined as land use shifted from agriculture to suburban. Baseflow nitrate export temporarily increased during the construction phase of SCM development in Dist-MD. This temporary pulse of nitrate may be attributed to the conversion of sediment control facilities to SCMs and increased subsurface flushing as infiltration SCMs came on line. During storm flow, Dist-MD tended to have less runoff and lower maximum specific discharge than Cent-MD for small events (<1.3 cm), but runoff responses became increasingly similar to Cent-MD with increasing precipitation (>1.3 cm). Mass export estimated during paired storm events indicated Dist-MD exported 30% less sediment and 31% more PP than Cent-MD. For large precipitation events, export of sediment and PP was similar among all three watersheds. Results suggest that distributed SCMs can reduce runoff and sediment loads during small rain events compared to centralized SCMs, but these differences become less evident for large events when peak discharge likely leads to substantial bank erosion.
雨水控制措施（SCMs）用于截留雨水和污染物。传统上，雨水控制措施是以集中方式安装，利用滞蓄来缓解洪峰流量。最近，越来越多地采用在源头附近处理径流的分布式雨水控制措施网络。本研究的目的是通过评估基流养分（NO-N和PO）浓度和通量、悬浮沉积物和颗粒态磷（PP）的暴雨径流输出以及径流特征的差异，来评估雨水控制措施布局不同的流域之间的差异。采用配对流域方法，比较了2004年至2016年一个森林流域（For-MD）、一个设有集中式雨水控制措施的郊区流域（Cent-MD）和一个设有分布式雨水控制措施的郊区流域（Dist-MD）的输出情况。结果表明，所有流域的基流硝酸盐（NO-N）浓度通常超过1毫克氮/升，在Dist-MD中最高。在过去10年的Dist-MD中，随着土地利用从农业转变为郊区，溪流基流和一口地下水井中的硝酸盐浓度均有所下降。在Dist-MD的雨水控制措施建设阶段，基流硝酸盐输出暂时增加。这种硝酸盐的暂时脉冲可能归因于沉积物控制设施转变为雨水控制措施，以及随着渗透式雨水控制措施投入使用，地下冲洗增加。在暴雨径流期间，对于小降雨事件（<1.3厘米），Dist-MD的径流量往往比Cent-MD少，最大比流量也更低，但随着降水量增加（>1.3厘米），径流响应变得越来越类似于Cent-MD。配对暴雨事件期间估算的质量输出表明，Dist-MD的沉积物输出比Cent-MD少30%，PP输出比Cent-MD多31%。对于大降水事件，所有三个流域的沉积物和PP输出相似。结果表明，与集中式雨水控制措施相比，分布式雨水控制措施在小雨事件期间可以减少径流和沉积物负荷，但对于大事件，当洪峰流量可能导致大量河岸侵蚀时，这些差异就不那么明显了。
