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Nonpoint source pollution control requires the implementation of best management practices (BMPs) at various locations in a watershed. One important aspect of the watershed strategy is to find the optimal placement and design of BMPs so that their combined effect is most cost-effective. An innovative method is presented for optimizing the placement and configurations of BMPs at the watershed scale. Heuristic optimization techniques are coupled with a watershed model, which is the agricultural Nonpoint Source Pollution model (AnnAGNPS) in this case, and BMP simulation module to find a least cost set of solutions that meet the pollutant load reduction requirements. An impoundment module imbedded in AnnAGNPS, and modified to address the sediment accumulation and resuspension effect, is used to provide the means of evaluating the long-term performance of detention ponds. A scatter search algorithm is applied to finding the least cost solution. The optimization framework developed herein provides a tool for stormwater management practitioners to examine and analyze the treatment efficiencies of stormwater control alternatives and to determine a robust and cost-effective design of stormwater treatment systems. [ABSTRACT FROM AUTHOR]

To mitigate the effects of urban stormwater runoff, onsite control measures, which are generally termed as best management practices (BMPs), have been widely used. In recent years, low impact development (LID), or a broader term, green infrastructure (GI), has gained worldwide recognition as the preferred control practices to alleviate the effects of urban stormwater runoff. These practices rely mostly on vegetation and media functions for runoff treatment. LID-BMPs have been identified as priority practices in China’s “Sponge City” projects. This study used SUSTAIN as a modelling tool to assess the ecological benefits of aggregate LID-BMPs for stormwater runoff control in Foshan New City, China. The input files for the model included four time series representing the runoff from impervious building roofs, other impervious land surfaces, pervious grass, and other pervious land surfaces, which were generated using precipitation data from the year 2008. The land uses in the study area were reclassified with the greening ratio and building density. Subwatersheds were delineated according to the topology and drainage pipe system. Based on the analysis of the technical information (e.g., design and performance) for selected LID-BMPs, which included rain barrels, green roofs, bioretention, porous pavements, swales, and wet ponds, four different aggregate LID-BMPs were designed. Setting annual flow volume, peak flow rate, and annual pollutant loads of COD, SS, TN, and TP as evaluation factors, the ecological benefits of the four aggregate LID-BMPs were first evaluated for a selected subwatershed. The best aggregate LID-BMPs were then applied to the entire study area. Results showed a 40% reduction in flow volume and over 60% reduction in all the pollutant loads. The optimization module of SUSTAIN was used to determine the least cost for the design of LID-BMPs in the study area that can meet the 60% annual flow volume control target. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a planning analysis of implementing low impact development (LID) type of stormwater best management practices (BMPs) for urban runoff control is presented. The Beijing Olympic Village (BOV) residential area in China was used as a case study. The original BOV stormwater system incorporated some LID BMPs such as porous pavements, green roofs and rainwater cisterns. After the 2008 Olympics, the BOV was converted to a residential complex and some stormwater facilities were modified for landscaping purposes. The performance of the original stormwater management system at the BOV residential area was first evaluated by using the model BMPDSS. BMPDSS is a best management practice (BMP) planning and analysis tool, which is capable of simulating BMP performance and optimizing BMP placement and design. The Storm Water Management Model (SWMM) was used to simulate pipe network hydraulics for the BOV. The present study then examined the performance associated with the BMP modifications for landscaping purposes, and then further BMP modifications designed for enhancing runoff control capabilities of the system. Using the 2008 rainfall data for Beijing, peak flow rate and runoff volume reductions under the three scenarios were calculated by using the coupled SWMM–BMPDSS framework and compared. Optimization analysis for BMP design aimed at achieving either maximum runoff control or total minimum system cost was then conducted. The results were used to form recommendations to the Beijing authorities for modifying the present stormwater management system in order to achieve more runoff control benefits. [Copyright &y& Elsevier]

Cost effectiveness is a major concern when implementing low impact development (LID) practices for urban stormwater management (USWM). To optimize LID layout, an efficient and more reliable method, namely, the Marginal-Cost-based Greedy Strategy (MCGS) was developed based on the economic law of increasing marginal costs (MCs) and the stepwise minimization of MCs. To verify its broad applicability, MCGS was applied in three case studies in China with different system settings and environmental goals. Both Cases I and II were watershed-scale studies in Suzhou City urban districts, but in Case II, the impact of future uncertainties (i.e., climate change, urban expansion, and LID performance degradation) on USWM system performance was considered. Case III was a block-scale study of the Xixian New District (a pilot “Sponge City” in China), which involved a rainwater pipe network and a complicated environmental goal. Compared with the extensively used but complicated NSGA-II, the MCGS performed better in terms of yielding more converged performance trade-offs, providing more choices for city planners, and requiring much less computational resources in all three cases. Meanwhile, MCGS established an optimal pathway for multi-stage LID layout planning. The success of MCGS indicated that the MC of a LID practice determined its favorability in an USWM system. [ABSTRACT FROM AUTHOR]

Low Impact Development Best Management Practices (LID-BMPs) have in recent years received much recognition as cost-effective measures for mitigating urban runoff impacts. In the present paper, a procedure for LID-BMPs planning and analysis using a comprehensive decision support tool was proposed. A case study was conducted to the planning of an LID-BMPs implementation effort at a college campus in Foshan, Guangdong Province, China. By examining information obtained, potential LID-BMPs were first selected. SUSTAIN was then used to analyze four runoff control scenarios, namely: pre-development scenario; basic scenario (existing campus development plan without BMP control); Scenario 1 (least-cost BMPs implementation); and, Scenario 2 (maximized BMPs performance). A sensitivity analysis was also performed to assess the impact of the hydrologic and water quality parameters. The optimal solution for each of the two LID-BMPs scenarios was obtained by using the non-dominated sorting genetic algorithm-II (NSGA-II). Finally, the cost-effectiveness of the LID-BMPs implementation scenarios was examined by determining the incremental cost for a unit improvement of control. [ABSTRACT FROM AUTHOR]