Sponge City Construction Research Articles

Study on sustainable development and construction of karst mountain city based on the concept of a sponge city.

In recent years, there has been rapid urbanization development in China. The rapid expansion of cities and the increase in the proportion of the area of impervious surfaces have caused urban flooding problems. The karst area in Southwest China is characterized by a sensitive ecosystem, poor self recovery ability and typical karst development. The problems of a fragile and imbalanced water ecology are particularly prominent in karst areas, making it necessary to explore the applicability of the concept of sponge cities in such environments. This study reviews the technical ideas, methods and concepts of sponge cities in China and abroad in recent years. Guiyang, a typical karst mountain city in China, was taken as an example in this study. This was because Guiyang has special hydrogeological characteristics as well as the current urbanization development processes that are affecting the water resources and the environment in the region. It is believed that the construction of mountain sponge cities in karst areas should be mainly through source reduction, process control and end management, combined with intelligent construction methods. Focus should be on strengthening the prevention and control of soil erosion in key areas and risk areas and on properly handling the relationship between urban construction and water resources and ecological environment protection.

Cost-Effectiveness Analysis of a Sponge City Construction Based on the Life Cycle Cost Theory—A Case Study of the Yanshan South Road Area of Qian’an City, China

In semi-humid regions of China, annual precipitation is not evenly distributed. Heavy, summertime rainfall with a short duration frequently causes urban flooding, and annual rainfall less than evaporation results in urban water scarcity. In 2014, Hebei Province’s Qian’an city was ranked among the first group of sponge city pilot cities. This paper investigates the historically flooded section of Yanshan South Road and its surrounding area in Qian’an, focusing on the cost of resolving an urban water problem. Using the storm flood management model (SWMM) and the life cycle cost (LCC) method, the waterlogging reduction effect and life-cycle cost of various low impact development (LID) scenarios were evaluated. Six rainfall design scenarios were simulated and calculated so that the hydrological performance and cost-effectiveness could be comprehensively evaluated to establish the economic value and effectiveness of implementing LID facilities. This study found that the cost-effectiveness values of sunken green space (SG), SG + infiltration ponds (IP) (3:1), SG + IP (1:1), and SG + IP (1:3) scenarios for infiltration LID schemes were relatively high, up to 2.10. In the infiltration-storage LID scheme, the cost-effectiveness of the SG + reservoirs (RE) (1:1) was grater, which was 1.84. In semi-humid regions, the regulation and storage of rainwater, regarding its collection and use, can be widely applied to the construction of sponge cities.

Benefit of Sponge City monetization based on "water footprint theory": cases of Xi'an and Guyuan.

China has proposed to build "Sponge City" to alleviate the problems of urban waterlogging, water shortage, ecological degradation, and water pollution. The benefits of Sponge City construction have become a focus of attention because of the considerable investment and the extensive participation of all sectors of society. This paper develops a model for monetizing urban, river, and regional benefits, by taking city and river areas as the research objects. This model is based on the regional water balance, water footprint theory, and the shadow price of water. This model monetizes the potential benefits of a Sponge City before construction. Our case study is Xi'an and Guyuan. Applying the benefits calculated at the 7% discount rate, the benefit/cost (B/C) ratios of the two locations are 3.86 and 0.93 times, respectively. Also, applying the benefits calculated at the 5% discount rate, the B/C ratios of the two locations are 5.41 and 1.31 times, respectively. In terms of urban benefits, the static payback periods of Xi'an and Guyuan are about 3.7 years and 15.3 years, respectively. In terms of regional benefits, they are about 4.0 years and 16.2 years, respectively. According to the results, the return of Sponge City construction in Xi'an and Guyuan is much higher than the investment but with some risks in the investment for social investors in Guyuan. In this paper, the model and the research results can provide some references for the research on the monetization of Sponge City benefits.

A core framework of "mountain management-water management-moist city" for sponge city special planning: The case of northwestern China.

Sponge city special planning represents a basis for sponge city construction in China. It has a leading role in problem-oriented, effect-centered comprehensive, and coordinated construction. In accordance with the Interim Provisions on the Formulation of Sponge City Special Planning, China has gradually established a standardized method for formulating sponge city special planning based on the “four-water” framework. While this method emphasizes the normalization of planning contents, it has limitations when dealing with regional characteristics. The present paper clarifies the purposes and demands of formulating sponge city special planning for semi-arid valley cities in northwestern China. It furthermore highlights the limitations of the standard method and suggests a three-level optimization, i.e., problem identification, target indicators, and system construction. Based on the framework of “mountain management–water management–moist city,” this paper proposes a set of ideas for formulating sponge city special planning. In this regard, the discussions are based on the formulation practice of Xining.

Thoughts on Sponge City Construction Based on the Current Situation of Urban Waterlogging

Thoughts on Sponge City Construction Based on the Current Situation of Urban Waterlogging

Pollution Characteristics and Risk Assessment of Heavy Metals in the Bioretention Systems of Sponge Cities

As an important water purification and seepage measure for sponge cities, biofiltration systems have been widely used in their construction in China. In order to identify the heavy metal accumulation, pollution, and its potential environmental risk in the biofiltration systems, this study examined the heavy metal contents and spatial distribution characteristics by taking the biofiltration systems of Yuelai new town, Chongqing, the first demonstration area of sponge city construction in China, as the research object, and conducted a risk evaluation of the pollution level and ecological environment in this new town using the contamination factor (CF), geo-accumulation Index (Igeo), and potential ecological risk coefficient (PERC). The results showed that, except for Mn, the average contents of Cu, Zn, Pb, Ni, and Cd in the biofiltration systems of Yuelai new town were 4.14, 1.77, 4.98, 1.23, and 6.51 times higher than the soil background values of Chongqing. In terms of spatial distribution, the contents of heavy metals in biofiltration systems along the roads in different functional areas showed great differences. The contents of Cu, Zn, Mn, Pb, Ni, and Cd in the industrial area were significantly higher than those of the same types of heavy metals in the biofiltration systems in other areas (P<0.05). The CF and Igeo showed that the pollution level of heavy metals was ranked as follows:Mn<Zn<Ni<Cu<Pb<Cd. Among them, Cu and Pb were highly polluted, Cd was severely polluted, and the PERC of Cd was 194.13, which indicated a high risk; the remaining heavy metals were at a minor risk. The pollution contribution of Cd to the composite PERC of all heavy metals was 78.73%, which was the major source of heavy metal potential risk. After the long-term operation of the biofiltration systems in a sponge city, certain environmental and ecological risks may exist later due to the accumulation of filler heavy metals. Hence, it is necessary to strengthen the operation management and carry out research on the non-polluted management of the filler of biofiltration facilities, to prevent them from becoming a new source of urban heavy metal pollution.

How do construct a sponge city that can improve residents' satisfaction? Evidence from a suburb of Huizhou City, China

The construction of the sponge city can effectively alleviate the problems of urban waterlogging and pollution and promote the city's sustainable development. However, few studies on sponge city construction take into account both natural background conditions and resident satisfaction. This study considers both physical and psychological benefits and presents a new integrated theoretical framework to improve urban runoff quality and the well-being of residents. The developed framework consists of two parts: sponge city control space identification and optimization design. The control space suitable for sponge city construction was identified, using the Eco-Importance-Resident Satisfaction Analysis (EIRSA) methodology, and the relationship between the basic needs of suburban residents and the current ecosystem service capacity was explored. The Multi-Criteria Decision Making (MCDM) method was used to optimize the design of the identified control space. The resident subjective visions and sponge city construction goals were used to determine the construction area and type of LID using GIS and the Storm Water Management Model (SWMM). The proposed framework was then applied to a suburb of Huizhou City, China, as a case study. This study analyzed the physical and psychological benefits of sponge city design schemes with different rainfall scenarios (S1, S2, S3, and S4) for the LID construction project. The results identified this scheme had met 90% or more of the region's volume capture ratio of annual rainfall constraints. Furthermore, >60% of the respondents were content with our planning scheme, with 21% being extremely satisfied, compared to only 2.1% satisfied, and 0.7% very satisfied. Considering the trade-off between ecological importance and resident satisfaction, it is a feasible strategy to build a sponge city that can improve residents' well-being in the future. The findings of this paper provide a detailed decision-making basis for the construction of sponge city in suburban areas.

Evaluation of comprehensive benefits of sponge cities using meta-analysis in different geographical environments in China.

With the rapid progress in urbanization, frequent urban waterlogging and non-point source pollution are threatening the living and health of human beings. Sponge city construction has become an effective means to curb urban waterlogging. Although related studies have explored the comprehensive benefits of sponge cities, few studies have been conducted on the effects of different geographical environments on runoff control and suspended solid (SS) removal. Based on 76 cities with sponge cities in China, this study used the meta-analysis method to evaluate the relationships of climate, terrain, underlying surface conditions, and construction area with the increase in the total annual runoff control rate and SS removal rate. The results reveal that the runoff control benefit can be significantly improved by sponge cities under the combined conditions of average annual precipitation of approximately 1000 mm, high fractional vegetation cover, sufficient soil fertility, a terrain slope i of ≤2%, and a permeability coefficient of strata of 100-200 m/d, especially in northern China, where the weight representing the quantity of comprehensive benefits was calculated to be 25.5%. In addition, the study results assist in reforming unfavorable geographical environments in the construction of sponge city, thus providing more effective solutions for tackling SS pollution. The most significant benefits of SS removal were obtained in north central China, where the weight was 21.4%. This study comprehensively investigated the effects of geographical environmental factors on the comprehensive benefits of sponge city reflected by the improvement in the total annual runoff control rate and the SS removal rate. The results will provide guidance for the planning and design of global sponge cities and effectively optimize the practice, scale, and location of existing construction based on specific geographical environments.

How does sponge city construction affect carbon emission from integrated urban drainage system?

The integrated urban drainage system has complicated sources of greenhouse gases (GHG) emissions, which is one of contribute to climate change. As a new model of low-carbon ecological city development in China, sponge city has great potential of carbon emission reduction. However, limited by the lack of awareness of the importance of carbon emissions from integrated urban drainage system, few studies have focused on the impact of sponge city construction on the carbon emissions from integrated urban drainage system. This study proposed an accounting framework for carbon emissions from integrated urban drainage system. The emission factor method was used to calculate carbon emissions. A case study was conducted in Xiamen, China, the carbon emission level of integrated urban drainage system and the carbon emission reduction effect of sponge city construction were discussed. The results show that the carbon emission from traditional city drainage system and sponge city drainage system accounts for about 3.4% and 1.7% of the city's carbon emission, respectively. Wastewater treatment and Sludge Treatment and Disposal are the main contributors to the carbon emissions from integrated urban drainage system. Electricity consumption is the main contributors to the indirect carbon emissions. Adjusting the sludge disposal method has the best carbon emission reduction effect, raising the standard of wastewater treatment plant tail water will lead to an increase in carbon emissions. Compared with the traditional city drainage system, the sponge city drainage system can reduce carbon emissions from integrated urban drainage system by an average of 49%, and the corresponding economic benefit was approximately 91–297 CNY/104 m3 wastewater. This study plays a positive role in understanding the carbon emission level of integrated urban drainage system and planning the low-carbon development of the city in the future.

Exploring the Determinants of Residents’ Behavior towards Participating in the Sponge-Style Old Community Renewal of China: Extending the Theory of Planned Behavior

In recent years, sponge-style old community renewal (SOCR) has attracted considerable attention as an essential component of urban renewal and sponge city construction in China. As a new method of community governance, the government has increasingly valued residents’ participation in the SOCR. However, as a new concept, the SOCR has not been studied from the perspective of management, and there are few explorations of residents’ participation in the research field. Thus, this study aimed to explore the determinants of residents’ behavior toward participating in the SOCR of China based on the extended theory of planned behavior (TPB), which will further promote residents’ engagement in the SOCR. Data from 1657 respondents were analyzed using the structural equation model (SEM) to verify the direct or indirect relationship between potential variables. The results show that residents’ participation cognition (RPC), attitude (RPA), and intention (RPI) all significantly affect residents’ participation behavior (RPB). The RPC can not only have an indirect impact on the RPB by influencing the RPA but also have an indirect impact on the RPB through the RPA and the RPI. This research not only expands the application boundary of the TPB but also enriches the knowledge system of residents’ participation and the SOCR. Several practical implications for promoting residents’ participation are obtained in the context of the SOCR projects.

Assessment and time–space difference analysis of sponge city construction potential: A case study in Jiangsu, China

AbstractThis paper constructs a sponge city construction potential evaluation index system, uses a variable fuzzy recognition model to evaluate the construction level of sponge cities in 13 prefecture‐level cities in Jiangsu Province from 2013 to 2019, and analyses its dynamic evolution trend based on Kernel density estimation. The analysis shows that the construction potential of sponge city in Jiangsu Province shows an overall upward trend, and the potential levels of 13 cities can be divided into three camps: Suzhou, Wuxi, Nanjing, Nantong and Changzhou are the first camps with higher potential; Yangzhou, Zhenjiang and Taizhou are the second camp of medium level; Xuzhou, Huai'an, Suqian, Yancheng and Lianyungang are the third camp of lower level. The overall situation is a trend of ‘big in the south and small in the north’. On this basis, the advantages and disadvantages of different cities and their development directions were further clarified, and a certain reference for promoting the construction of sponge city was provided.

Precise estimation of subsurface moisture content based on laboratory measurement and 3D GPR field survey

The Sponge City construction currently undergoing in China aims to enhance the moisture capacity of urban pedosphere, and subsurface moisture content (SMC) is proposed to evaluate the effect of improvement. Different ground-penetrating radar (GPR) techniques have been used in previous studies to estimate moisture content, however, very few has assessed the potential of combing 2D common offset (CO) GPR with 3D multichannel GPR to resolve SMC estimates at the complex filed scale. In this paper, modified velocity analysis of in-situ 3D GPR common-midpoint (CMP) datasets was used together with 2D GPR laboratory calibration procedure to investigate spatial moisture variation and the impact of surface pavement and soil heterogeneity on subsurface water dynamics. Precise and reliable moisture information under two field sites (i.e., sponge pavement site and asphalt pavement site) was obtained, which further allowed us to quantitative characterize SMC distribution and its associated dynamics within the shallow vadose zone, and most importantly to investigate the coupling mechanism between subsurface water fluctuations with surface pavement conditions and subsoil moisture capacity in urban near surface environment. Additionally, through contrastive analysis, the superior performance of novel sponge material to detain and transit rainwater was highlighted. Data and results presented in this research provide pioneer reference for Sponge City construction and other engineering applications.

Comprehensive performance evaluation of stormwater management measures for sponge city construction: A case study in Gui'an New District, China

AbstractClimate change and rapid urbanization have increased pressure on drainage systems, posing new challenges to preventing and controlling urban waterlogging. In 2013, China proposed the Sponge City, a strategic measure for urban waterlogging control. This study quantifies the effects of stormwater management measures in runoff reduction for different levels of rainfall and conducts a one‐dimensional visual analysis of urban waterlogging risks. At the same time, the best cost‐effective scheme is determined based on life‐cycle cost, analytic hierarchy process, and regret decision theory. The results showed stormwater management measures could realize the function of runoff control and waterlogging prevention, especially under low precipitation. However, these measures were still not enough to eliminate waterlogging risk. Combined measures have stronger runoff control capabilities than single measures. Considering economic, environmental, and operational impacts comprehensively, the combined measures of bio‐retention (BR), permeable pavement (PP), and green roof (GR) were determined as the best cost‐effective scheme because of the lowest regret value. The proposed method is helpful to provide reference and decision‐making basis for the construction of sponge cities in the future.

Effects of Different Factors on the Performance of Recycled Aggregate Permeable Pavement Concrete.

Urban construction has produced a large amount of construction waste which has caused huge environmental problems. The sponge city is the development direction of urban construction, and permeable pavement concrete is an important material for sponge city construction. To see the law influencing different factors on the performance of recycled aggregate permeable pavement concrete, different water binder ratios, recycled aggregate particle gradations, ordinary aggregate substitution rates, and fly ash and admixture contents are designed to prepare permeable concrete. The compressive strength, permeability coefficient, frost resistance, and pore structure of permeable concrete are tested. The results show that when the replacement rate of recycled aggregate is 50%, the 28-d strength of concrete with a 0.25 water binder ratio can reach 28.9 MPa, and the permeability coefficient is 13.26 mm/s. The addition of fly ash will reduce the compressive strength, and the permeability coefficient increases first and then decreases with the increase of the fly ash content. When the mass fraction of fly ash instead of cement is 12%, the 28-d strength is 94.8% of that of the cement group, and the permeability coefficient can reach 14.03 mm/s. A water-reducing agent can obviously improve the workability of permeable concrete; the best content of the water-reducing agent is 0.2% of the cement mass. A reasonable amount of fly ash and water-reducing agent can optimize the number of harmless holes and less harmful holes in the concrete to improve the frost resistance and strength after the freeze–thaw, and the frost resistance is F150. This study provides a theoretical basis and technical guarantee for the resource utilization of recycled aggregate in permeable pavement concrete.

Urban Runoff Control and Sponge City Construction

Rapid population growth, urbanization and high-intensity human activities cause a multitude of extremely serious environmental problems all over the world [...]

Causal Analysis and Prevention Measures for Extreme Heavy Rainstorms in Zhengzhou to Protect Human Health.

This study focused on the extreme heavy rainstorm that occurred in Zhengzhou in July 2021; approximately 380 people were killed or missing as a result of this storm. To investigate the evolution behaviors of this rainstorm and take corresponding prevention measures, several methods and models were adopted, including cloud modeling, preliminary hazard analysis (PHA), fault tree analysis (FTA), bow-tie modeling, and chaos theory. The main reasons for this rainstorm can be divided into the following three aspects: force majeure, such as terrain and extreme weather conditions, issues with city construction, and insufficient emergency rescue. The secondary disasters caused by this rainstorm mainly include urban water logging, river flooding, and mountain torrents and landslides. The main causes of the subway line-5 accident that occurred can be described as follows: the location of the stabling yard was low, the relevant rules and regulations of the subway were not ideal, insufficient attention was given to the early warning information, and the emergency response mechanism was not ideal. Rainstorms result from the cross-coupling of faults in humans, objects, the environment, and management subsystems, and the evolution process shows an obvious butterfly effect. To prevent disasters caused by rainstorms, the following suggestions should be adopted: vigorously improve the risk awareness and emergency response capabilities of leading cadres, improve the overall level of urban disaster prevention and mitigation, reinforce the existing reservoirs in the city, strengthen the construction of sponge cities, and improve the capacity of urban disaster emergency rescue.

The Response of Runoff Pollution Control to Initial Runoff Volume Capture in Sponge City Construction Using SWMM

Source facilities can manage stormwater runoff pollutants while also limiting runoff volume in China’s sponge city construction. However, there is no apparent link between source volume control and runoff pollution reduction. This research uses SWMM to develop a model based on the basic data of a city’s catchment zone in northern China in order to statistically examine the response relationship between the initial runoff volume capture of sponge city construction and the reduction effect of stormwater runoff pollution. Based on the dimensionless constant of the runoff pollution control curve, we suggested a novel approach for evaluating runoff pollution control effectiveness. This method was used to examine the response relationship between runoff volume control and runoff pollution control in three typical initial runoff volume capture facilities in the study area, namely bioretention, permeable pavement, rain barrels, and terminal storage tanks, under various design rainfall conditions. The dimensionless constant (Dc) has good practical application value and can quantitatively quantify the control effect of various facilities on stormwater runoff pollution. The Dc value of the source facilities is higher than that of the terminal control facilities, indicating that the source facilities have a higher ability to reduce rainwater runoff pollution than the terminal facilities, particularly the infiltration facilities. The research ideas and evaluation methods proposed in this paper provide an alternative approach for selecting and optimizing facilities during the planning and designing stages of sponge city construction, which can also be used in the monitoring and evaluation stage after completion to carry out a more effective evaluation of sponge facilities’ effects.

SCC-UEFAS, an urban-ecological-feature based assessment system for sponge city construction

An effective sponge city construction evaluation system plays a crucial role in evaluating sponge city construction schemes. The construction of a sponge city evaluation system still faces challenges related to incomplete index selection and unscientific weight division. Limited studies have focused on the comprehensive assessment of sponge city construction in the early stages. This study constructed a scientific assessment indicator system and a quantitative indicator weight at all levels by literature review and statistical analysis methods from an objective perspective. To demonstrate how to utilize our evaluation methods, three construction schemes randomly generated by MATLAB were evaluated under evaluation states of constant weight and variable weight, respectively. Scheme 3 had the highest score of 0.638 under the constant weight assessment, but it cannot practically be the final construction scheme due to the imbalance between indicators. Compared to the constant weight assessment, a variable weight assessment can effectively balance the states of the evaluation index with changes in the decision variable. Among the three schemes, Scheme 2 is the best choice with a value of 0.0355 under variable weight evaluation due to punishment and incentives in the variable weight method. The concept of “punishing” a disadvantageous indicator and “motivating” an advantageous indicator increases the relative advantages of the indices, ultimately affecting the assessment results of schemes and leading to a more balanced state. This study provides reasonable analysis and decision-making mechanisms to support decision-making and guide the scientific selection of a construction scheme.

Required number of years of rainfall data to determine the design rainfall depth of source control in sponge city construction

Study Region: ChinaStudy Focus: In sponge city construction in China, rainfall data is the key to determining the rainwater source control scale. However, changes in rainfall characteristics can reduce the representativeness of the data. To obtain stable volume capture ratios (VCRs) of the annual rainfall through as little rainfall data as possible, this paper compares daily rainfall data from 159 cities in China in recent decades and finds the minimum number of years required to maintain stable VCRs under different design rainfalls. Finally, it gives the recommended observation periods (OPs) for different regions. New Hydrological Insights for the Region: For the last 35 years, the variation of daily rainfall in 75% of cities in China has been less than 0.66 mm, and the variation of skewness is less than 0.62. In general, the longer the observation period, the smaller the calculated VCR anomaly value and variation gradient will be. About 10% of cities cannot achieve stable VCRs by increasing the number of years of data. The denser urban distributed area needs larger OPs to determine the stable VCR; with the increase in design rainfall, the required OPs will also be lowered; in most cities, the VCR calculation does not require 30 years of rainfall data.

Grid-quantification study on the effect of rapid urbanization on hydrological processes

Abstract Hydrological processes such as evaporation, infiltration, and runoff are affected not only by natural climate change but also by land cover and soil conditions. The impact of urbanization on the key elements of the hydrological process is worth studying in the context of rapid urbanization. This paper combines the soil-land use index grid and the GSSHA model to quantitatively study the impact of land use on urban hydrological processes under the background of the changing urbanization stage. The results show that with the increase in land development and utilization activities, the hydrological process will transform. When grassland and woodland are converted to construction land, the changes in runoff, infiltration, and evaporation are the largest. The runoff depth increased by 0.94 × 10−1 ∼ 2.42 × 10−1 mm/km2, infiltration depth decreased by 0.80 × 10−1 ∼ 2.18 × 10−1 mm/km2, and evaporation decreased by 0.14 × 10−1 ∼ 0.28 × 10−1 mm/km2. In the transition from forest land to grassland, from cultivated land to forest land, and from cultivated land to grassland, the increase of infiltration contributed over 80% to the decrease of runoff process. This provides a scientific basis for future urban planning and sponge city construction.