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

The predictions of flood hazard over the design life of a hydrological project are of great importance for hydrological engineering design under the changing environment. The concept of a nonstationary flood hazard has been formulated by extending the geometric distribution to account for time-varying exceedance probabilities over the design life of a project. However, to our knowledge, only time covariate is used to estimate the nonstationary flood hazard over the lifespan of a project, which lacks physical meaning and may lead to unreasonable results. In this study, we aim to strengthen the physical meaning of nonstationary flood hazard analysis by investigating the impacts of climate change and population growth. For this purpose, two physical covariates, i.e., rainfall and population, are introduced to improve the characterization of nonstationary frequency over a given design lifespan. The annual maximum flood series of Xijiang River (increasing trend) and Weihe River (decreasing trend) are chosen as illustrations, respectively. The results indicated that:(1) the explanatory power of population and rainfall is better than time covariate in the study areas;(2) the nonstationary models with physical covariates possess more appropriate statistical parameters and thus are able to provide more reasonable estimates of a nonstationary flood hazard; and (3) the confidences intervals of nonstationary design flood can be greatly reduced by employing physical covariates. Therefore, nonstationary flood design and hazard analysis with physical covariates are recommended in changing environments.

Section: Preliminary Data Analysismentioning

confidence: 99%

“…However, the direct use of urbanisation covariate is difficult because of the difficulty in reliable projection of future urbanisation. Thus, to examine the possible impacts of urbanisation on flood events, researchers have used a comprehensive social-economic covariate, i.e., population, as a proxy of urbanisation [19,35,36].…”

Section: Introductionmentioning

confidence: 99%

Nonstationary Flood Hazard Analysis in Response to Climate Change and Population Growth

Yan

et al. 2019

“…Researchers have different focuses on zoning functional areas of sponge city [56,57], but they did not consider the issue from the perspective of the integrity of the urban ecosystem. The sponge city is a strategy for integrated urban water management to construct benign interactions between the social-economic system and the urban water cycle [58]. According to the interpretation of the guidelines, one of the purposes of sponge city planning is to clarify the sponge city construction strategy and delimit the sponge city construction subareas [20].…”

Section: Zoning the Functional Areas For The Sponge City With Targetementioning

confidence: 99%

Constructing the Ecological Security Pattern for Sponge City: A Case Study in Zhengzhou, China

Dong

Zhang

2019

Waterlogging is becoming a severe and universal phenomenon in China, so the construction of sponge cities is proposed to address urban water problems abiding by the overall principles of ecological priority and low-impact development. The ecological security pattern (ESP) is an effective way to balance rapid urbanization and ecological protection. Taking Zhengzhou as an example, this study, performed a geographic information system (GIS) modeling, which constructed a targeted ESP for the construction of a sponge city based on comprehensive analysis of multi-factor water ecological sensitivity. Compared to previous studies of ESP, some improvements were made in the identification method of ecological sources, corridors, and nodes. By analyzing the ESP, the study divided the whole city into different construction zone. Through different protection and planning strategies for these areas, the integration and connectivity of the ecological sources can be improved, and thus, urban ecological security can be improved. The ESP for sponge city is a relatively more systematic and scientific way to guide the construction of a sponge city, and can be used for reference to other cities in the process of sponge city construction.

“…Deviating from the conventional "rapid-draining" approach, this new paradigm called for the use of natural processes as part of the urban runoff control strategy. During 2015 and 2016, a total of 30 cities were selected as pilot cities to implement the sponge city in China [5][6][7]. Many studies about sponge city construction in China have evaluated the hydrological effects of low-impact development (LID) controls implementation.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Sponge City Construction for Reducing Directly Connected Impervious Areas on Hydrological Responses at the Urban Catchment Scale

Liang

Zhang

Xia

et al. 2020

Low-impact development (LID) has been widely used at both site-specific and local scales to try and mitigate the impact of urban stormwater runoff caused by increasing impervious urban areas. Recently, the concept of a “sponge city” was proposed by the Chinese government, which includes LID controls at the source, a pipe drainage system midway, and a drainage system for excess stormwater at the terminal. There is a need to evaluate the effectiveness of sponge city construction at the large urban catchment scale, particularly with different spatial distributions of LIDs that reduce directly connected impervious areas (DCIAs). In this paper, the performances of five design scenarios with different spatial distributions but same sizes of LID controls at the urban catchment scale were analyzed using a geographic information system (GIS) of the United States Environmental Systems Research Institute (ESRI)—based Storm Water Management Model (SWMM) of the United States Environmental Protection Agency (USEPA) and MIKE 11 of Danish Hydraulic Institute (DHI) in Xining City, China. Results confirmed the effectiveness of sponge city construction in reducing the urban stormwater runoff. The hydrological performance reduction was positively correlated and linearly dependent on DCIA reduction. Peak flow reduction was most sensitive to DCIA reduction, followed by runoff volume and peak time. As rainfall intensity increased, the hydrological performance was more sensitive to rainfall intensity than DCIA reduction. Results of this study provide new insights for stormwater managers to implement LID more effectively at the urban catchment scale.