Abstract
Abstract China recently commenced the Sponge City initiative for the effective management of urban stormwater runoff. Numerous studies have been carried out to evaluate the cost-effectiveness of low impact development (LID) practices in Sponge City planning and implementation. However, most of the studies were at the site- or subcatchment scale, and few were conducted at the watershed scale, given the dramatically increased routing complexity and number of decision variables. This study demonstrates the cost-effective Sponge City planning process for a 25.90 km2 high-plateau watershed in southwest China. The Stormwater Management Model was coupled with the System for Urban Stormwater Treatment and Analysis Integrated (SUSTAIN) model to perform both continuous simulations and watershed-level optimization analyses, using the reduction of 85% annual runoff volume as the optimization target. Based on over 11,000 optimization runs, a near-optimal aggregated LID scenario was identified for each subcatchment. The aggregated LID size was first converted into a generic LID storage volume for individual subcatchments, and the storage volume was then disaggregated into site-level LID layouts regarding specific site conditions. The disaggregated LID layout yielded an annual average runoff volume reduction of 87.61% and close to 85% reduction for the annual average total suspended solids, total nitrogen, and total phosphorus loads. The systematic approach outlined in this study could be used for watershed-level Sponge City planning and implementation analyses in other cities.
Highlights
We developed a SUSTAIN model for a 25.90 km2 watershed in the Haidong New District (HND) in southwest China
Composite Low impact development (LID) volumes were identified for each subcatchment through the optimization analysis, and the results were disaggregated to site-scale LIDs based on specific site conditions and engineering judgment
The resulting site-scale LID implementation reduced the annual average runoff volume by 87.61%, and the reduction of annual pollutant load reductions for TSS, TN, and TP were close to 85%, exceeding the Sponge City requirements for runoff volume control
Summary
Urbanization converts the natural landscape into impervious surfaces and adversely alters the hydrologic cycle, resulting in increased peak flow rates, runoff volume, and pollutant load, as well as decreased groundwater infiltration In the meantime, proposed water sensitivity urban design to protect degrading urban water resources through a range of practices, including stormwater recycling and reuse, and the goal is to make cities more sustainable, livable, and resilient (Brown et al ; Ashley et al )
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