Quantitative analysis of impact of green stormwater infrastructures on combined sewer overflow control and urban flooding control

Stimulated by the recent USEPA＇s green stormwater infrastructure （GSI） guidance and policies, GS1 systems have been widely implemented in the municipal area to control the combined sewer overflows （CSOs）, also known as low impact development （LID） approaches. To quantitatively evaluate the performance of GSI systems on CSO and urban flooding control, USEPA-Stormwater Management Model （SWMM） model was adopted in this study to simulate the behaviors of GSI systems in a well- developed urban drainage area, PSW45, under different circumstances. The impact of different percentages of stormwater runoff transported from impervious surfaces to the GSI systems on CSO and urban flooding control has also been investigated. Results show that with current buildup, GSI systems in PSW45 have the best performance for low intensity and short duration events on both volume and peak flow reductions, and have the worst pertbrmance tor high intensity and long durataon events. Since the low intensity and short duration events are dominant from a long-term perspective, utilizing GSI systems is considered as an effective measure of CSO control to meet the long-term controlstrategy for PSW45 watershed. However, GSI systems are not suitable for the flooding control purpose in PSW45 due to the high occurrence possibility of urban flooding during or after high intensity events where GSI systems have relatively poor performance no matter for a short or long duration event,

Research on Urban Carbon Emission Inventory and Its Application in Planning

This paper systematically reviewed related studies on urban carbon emission inventory, and especially analyzed current studies on the urban greenhouse gas inventory in China. Through comparative studies of four cases, it systematically discusses the application of urban carbon emission inventory in low carbon urban planning as a response to climate change, it thus concluded that city planners in China have duty-bound obligations and responsibilities to apply low carbon ideas into urban and regional planning, and the in-depth study on greenhouse gas emission inventory is undoubtedly of great significance and scientific value to mitigate climate change.

A new strategy for integrated urban water management in China：Sponge city

Urban water-related problems associated with rapid urbanization, including waterlogging, water pollution, the ecological degradation of water, and water shortages, have caused global concerns in recent years. In 2013, in order to mitigate increasingly severe urban water-related problems, China set forth a new strategy for integrated urban water management(IUWM) called the "Sponge City". This is the first holistic IUWM strategy implemented in a developing country that is still undergoing rapid urbanization, and holds promise for application in other developing countries. This paper aims to comprehensively summarize the sponge city. First, this paper reviews prior studies and policies on urban water management in China as important background for the sponge city proposal. Then, the connotations, goals, and features of the sponge city are summarized and discussed.Finally, the challenges, research needs, and development directions pertinent to the sponge city are discussed based on investigations and studies conducted by the authors. The sponge city in China has a short history—given this, there are many issues that should be examined with regard to the stepwise implementation of the Sponge City Programme(SCP). Accordingly, the authors perceive this study as only the beginning of abundant studies on the sponge city.

Green Eco-District Regulatory Plan Decision Tool–Carbon Accounting Standard Protocol

Green eco-district planning and construction occupies a very important position in China's future low carbon urbanization roadmap because the experience gained through practice will provide cities with a technical pathway to manage climate change and reduce carbon emissions. However, during the current preparation and implementation stage of the green eco-district plans, both the planning management departments and planning design institutes are faced with the problem of how to quantify the greenhouse gases(GHG) emissions, especially the CO_2 emissions, when approval decisions are to be made. Aiming at setting up a carbon accounting protocol within the statutory framework of China's green eco-district planning and construction management system, this paper argues that it is important to incorporate the GHG emission inventory into the statutory regulatory planning system, and discusses the technical issues and coping measures for assessing carbon emissions at the district level. It proposes to refine the Activity Data(AD) and Emission Factors(EF) in the current China's National GHG Inventory and set up the urban district carbon accounting protocol based on nine sectors. These nine emission accounting sectors are established according to the key policy and function as defined in the statutory local regulatory plans under the present planning system in Chinese cities. Taking planning and construction management at the district level as a platform to control carbon emissions, it develops an initial carbon accounting protocol suitable for China's green eco-districts which can be applied in both the existing and planned urban areas, and be integrated into the decision making process of the local planning process.

Determination of urban runoff coefficient using time series inverse modeling

Runoff coefficient is an important parameter for the decision support of urban stormwater management. However, factors like comprehensive land-use type, variable spatial elevation, dynamic rainfall and groundwater elevation, make the direct estimation of runoff coefficient difficult. This paper presented a novel method to estimate the urban runoff coefficient using the inverse method, where observed time-series catchment outfall flow volume was employed as input for the water balance model and runoff coefficients of different catchments were treated as unknown parameters. A developed constrained minimization objective function was combined to solve the model and minimized error between observed and modeled outfall flow is satisfactory for the presenting of a set of runoff coefficients. Estimated runoff coefficients for the urban catchments in Shanghai downtown area demonstrated that practice of low impact design could play an important role in reducing the urban runoff.

Fifty Years of Water Sensitive Urban Design, Salisbury, South Australia

Australia has developed extensive policies and guidelines for the management of its water. The City of Salisbury, located within metropolitan Adelaide, South Australia, developed rapidly through urbanisation from the 1970s. Water sensitive urban design principles were adopted to maximise the use of the increased rim-off generated by urbanisation and ameliorate flood risk. Managed aquifer recharge was introduced for storing remediated low-salinity stormwater by aquifer storage and recovery （ASR） in a brackish aquiter for subsequent lrngatlon. Ibis paper outlines now a municipal government has progressively adopted principles of Water Sensitive Urban Design during its development within a framework of evolving national water policies. Salisbury＇s success with stormwater harvesting led to the formation of a pioneering w aterbusiness that includes linking projects from nine sites to provide a non-potable supply of 5 ×10^6 m^3 year. These installations hosted a number of applied research projects addressing well configuration, water quality, reliability and economics and facilitated the evaluation of its system as a potential potable water source. The evaluation showed that while untreated stonnwater contained contaminants, subsurface storage and end-use controls were sufficient to make recovered water sale for public open space irrigation, and with chlorination acceptable lbr third pipe supplies. Drinking water quality could be achieved by adding microfiltration, disinfection with UV and chlorination. The costs that would need to be expended to achieve drinking water safety standards were found to be considerably less than the cost of establishing dual pipe distribution systems. The full cost of supply was determined to be AUD$1.57 m ＂ for non-potable water for pubhc open space lrngatlon much cheaper than mares water, AUD $3.45 m at that time. Producing and storing potable water was found to cost AUDS1.96 to $2.24 m .