Overflow Simulation and Optimization of a Drainage System in an Urban Area in the Northern Anhui Plain

Urban waterlogging control: A novel method to urban drainage pipes reconstruction, systematic and automated

Abstract. Urban waterlogging, as a common natural disaster in China, seriously restricted the development of society. Nowadays, while the computer technology is developing continuously, the urban waterlogging model is also constantly improved. These models can simulate the process of urban waterlogging, but the simulation results are not intuitive. So it is difficult for users to understand how the model works. Therefore, it is important to find a way to show the simulation results so that people can see the waterlogging simulation intuitively. Cesium, as a three-dimensional visualization platform, can reproduce the process of the urban waterlogging. It will make sense if we could show the simulation results on the Cesium platform. Nowadays, many studies focus on both urban waterlogging and visualization methods. However, there are fewer studies on the combination of the two, especially the interactive visualization of urban waterlogging under parameter adjustment. Therefore, this paper mainly focuses on urban three-dimensional interactive visualization method based on Cesium.On the one hand, the three-dimensional visualization of the urban waterlogging simulation facilitates the intuitive expression of the simulation results. Without visualization, the results of the simulation are only some complicated and unintuitive figures for most non-experts. On the other hand, visualization based on the Cesium platform can better adapt to the cross-platform application. It can better meet the needs of different terminal devices of different users for the visualization platform, so that users can obtain the disaster information more accurately, consistently and intuitively. It is conducive for management departments to respond to sudden disasters more quickly and efficiently.This research aims to propose a three-dimensional dynamic interactive visualization method for urban waterlogging. Particularly, we hope to find out how to integrate urban waterlogging model and 3D visualization platform. With this 3D visualization platform, we can combine the advantages of the SWMM (Storm Water Management Model) and Cesium platform. Using this platform, it will be easier and more effective to respond to disasters for the masses and management departments.The following two issues are resolved in this study: i) How do model parameters affect the urban waterlogging simulation and visualization results? ii) How to integrate SWMM and Cesium 3D visualization platform?In order to address the above research objectives, we will apply the following methodologies: i) We will analyse the parameters of the SWMM for the urban waterlogging visualization. Under the premise of understanding the development process of the urban waterlogging, we will analyse the modelling principle of the urban waterlogging, the mechanism of each part of the model separately. Then, we will find out the method of determining the model parameters of urban waterlogging and its influence on the simulation visualization results. ii) We will study integration methods of urban waterlogging model and 3D visualization platform. We will analyse the mechanism and process of urban waterlogging. We will also calculate the urban waterlogging process data by the SWMM, and establish a three-dimensional visualization platform by the node.js and Cesium, which can dynamically show the process of urban waterlogging. iii) We will complete the design and implementation of the interactive visualization platform of urban waterlogging. According to the above research, taking the Xianlin Campus of Nanjing Normal University as an example, we will build a dynamic interactive visualization system of urban waterlogging simulation based on Cesium. We will also verify the effectiveness of the system by comparing it with actual flood situation.With this study, we expect to answer how model parameters affect the urban waterlogging simulation and visualization results. As expected results, we plan to build an interactive visualization system of urban waterlogging simulation based on Cesium, publish the flood calculation results into the 3D scene. This will make urban waterlogging process shown in the 3D scene. This visualization system is designed for different users, including specialists, government and individual. It means that you can use the system easily even if you are non-cartographers or non-IT-specialists.

With the rapid urbanization and increasing urban impervious areas in China, urban water-logging has become increasingly serious. The concept of sponge city was proposed based on the low impact development (LID) idea. We analyzed the impacts of landscape pattern optimization scenario on urban surface runoff and rainwater control ability in central urban area of Shen-Fu New Town in Liaoning Province. The storm intensity formula was used to construct rainfall process in different return periods. The landscape patterns of the study area were optimized based on sponge city concept. The storm water management model (SWMM) was used to simulate the differences of surface runoff and rainwater regulation ability under the pre-planning scenario and the landscape pattern optimization scenario. The results showed that total runoff and runoff coefficient of the study area were increased with increasing rainfall return period. In the same rainfall return period, the runoff coefficient was significantly reduced. The reduction of total runoff gradually increased, being 2.94, 3.58, 3.72, and 4.19 mm during the 1-year, 3-year, 5-year and 50-year return period under landscape pattern optimization scenario. The corresponding reduction rate was gradually reduced, being 23.9%, 16.4%, 14.3%, and 9.3%, respectively. Landscape pattern optimization scenario could meet the requirements that the rainfall was controlled at 20.8 mm when the rainfall return period p=1 year, the rainwater pipe network would not overload when p=3 years, and the river channel would not overflow when p=50 years.

This study presents a water accumulation diffusion algorithm to spatially simulate rainstorm-induced waterlogging for people’s lives and property safety. Taking part of Jinfeng District in Yinchuan City, China, as a study area, a storm water management model (SWMM) model is constructed with the aid of geographic information system (GIS) and remote sensing (RS) technologies. GIS is used to divide sub-catchments, generalize drainage system, set parameters, construct spatial geodatabase, and identify flood extents and depths. RS is used to obtain land-use/land-cover information. The water accumulation diffusion algorithm is then designed using the strategies of the dynamic interactions between pipes and surface and between central pixel and its neighbourhood pixels to transform water accumulation volume of sub-catchment into the submerged range and water accumulation depth. Positions, extents, depths, and volumes of water accumulation from pipe network and surface are simulated, respectively. The spatial simulation precisions of rainstorm waterlogging from the pipe network and surface are verified according to the measured and cyber rainstorm data, respectively. The results show that (1) the number of water accumulation nodes increases with the increase of rainfall intensity; (2) urban waterlogging is mainly distributed in the intersects of roads, low depressions and the aged drainage networks; and (3) spatial simulation of urban rainstorm waterlogging based on the GIS, RS, and SWMM techniques and the water accumulation diffusion algorithm is reliable. The results can provide decision-makings to predict rainstorm waterlogging, design drainage network, and construct a sponge city.

In a highly urbanized area, land availability is limited for the installation of space consuming stormwater systems for best management practices (BMPs), leading to the consideration of underground stormwater treatment devices connected to the stormwater pipe system. The configuration of a stormwater pipe network determines the hydrological and pollutant transport characteristics of the stormwater discharged through the pipe network, and thus should be an important design consideration for effective management of stormwater quantity and quality. This article presents a multi-objective optimization approach for designing a stormwater pipe network with on-line stormwater treatment devices to achieve an optimal trade-off between the total installation cost and the annual removal efficiency of total suspended solids (TSS). The Non-dominated Sorted Genetic Algorithm-II (NSGA-II) was adapted to solve the multi-objective optimization problem. The study site used to demonstrate the developed approach was a commercial area that has an existing pipe network with eight outfalls into an adjacent stream in Yongin City, South Korea. The stormwater management model (SWMM) was calibrated based on the data obtained from a subcatchment within the study area and was further used to simulate the flow rates and TSS discharge rates through a given pipe network for the entire study area. In the simulation, an underground stormwater treatment device was assumed to be installed at each outfall and sized proportional to the average flow rate at the outfall. The total installation cost for the pipes and underground devices was estimated based on empirical formulas using the flow rates and TSS discharge rates simulated by the SWMM. In the demonstration example, the installation cost could be reduced by up to 9% while the annual TSS removal efficiency could be increased by 4% compared to the original pipe network configuration. The annual TSS removal efficiency was relatively insensitive to the total installation cost in the Pareto-optimal solutions of the pipe network design. The results suggested that the installation cost of the pipes and stormwater treatment devices can be substantially reduced without significantly compromising the pollutant removal efficiency when the pipe network is optimally designed.

The core of comprehensive treatment effect of water environment in river basin lies in pipe network system. The blockage of urban drainage pipe network is one of the main reasons affecting the healthy operation of urban drainage network system. So the intelligent analysis method of urban drainage pipe network blockage diagnosis can quickly find the problems of urban drainage pipe network and improve the operation and maintenance efficiency of urban drainage pipe network. In this paper, through the analysis of rainfall data, rainfall and sewage pipe network flow variation regular pattern, the change range, the essay obtains the rain and sewage pipe network blockage diagnosis threshold. Combined with the urban intelligent drainage pipe network system, through the customized setting of pipe network blockage threshold, the rapid diagnosis and early warning of the blockage problem of the drainage pipe network are realized, and the healthy operation of the urban drainage network is guaranteed.

The rapid expansion of urban drainage pipe networks, driven by economic development, poses significant challenges for efficient monitoring and management. The complexity and scale of these networks make it difficult to effectively monitor and manage the discharge of urban domestic sewage, rainwater, and industrial effluents, leading to illegal discharges, leakage, environmental pollution, and economic losses. Efficient management relies on a rational layout of drainage pipe network monitoring points. However, existing research on optimal monitoring point layout is limited, primarily relying on manual analysis and fuzzy clustering methods, which are prone to human bias and ineffective monitoring data. To address these limitations, this study proposes a coupled model approach for the automatic optimization of monitoring point placement in drainage pipe networks. The proposed model integrates the information entropy index, Bayesian reasoning, the Monte Carlo method, and the stormwater management model (SWMM) to optimize monitoring point placement objectively and measurably. The information entropy algorithm is utilized to quantify the uncertainty and complexity of the drainage pipe network, facilitating the identification of optimal monitoring point locations. Bayesian reasoning is employed to update probabilities based on observed data, while the Monte Carlo method generates probabilistic distributions for uncertain parameters. The SWMM is utilized to simulate stormwater runoff and pollutant transport within the drainage pipe network. Results indicate that (1) the relative mean error of the parameter inversion simulation results of the pollution source tracking model is linearly fitted with the information entropy. The calculation shows that there is a good positive linear correlation between them, which verifies the feasibility of the information entropy algorithm in the field of monitoring node optimization; (2) the information entropy algorithm can be well applied to the optimal layout of a single monitoring node and multiple monitoring nodes, and it can correspond well to the inversion results of the tracking model parameters; (3) the constructed monitoring point optimization model can well realize the optimal layout of monitoring points of a drainage pipe network. Finally, the pollution source tracking model is used to verify the effectiveness of the optimal layout of monitoring points, and the whole process has less human participation and a high degree of automation. The automated monitoring point optimization layout model proposed in this study has been successfully applied in practical cases, significantly improving the efficiency of urban drainage network monitoring and reducing the degree of manual participation, which has important practical significance for improving the level of urban water environment management.

Urban flooding occurs frequently in many regions of China. To reduce the losses caused by urban flooding, sponge city (SPC) and low-impact development (LID) have been carried out in many Chinese cities. However, urban flooding is influenced by various factors, such as climate, land cover characteristics and nearby river networks, so it is necessary to evaluate the effectiveness of LID measures. In this study, the Storm Water Management Model (SWMM) was adopted to simulate historical urban storm processes in the mountainous Fragrance Hills region of Beijing, China. Subsequently, numerical simulations were performed to evaluate how various LID measures (concave greenbelt, permeable pavement, bio-retention, vegetative swales, and comprehensive measures) influenced urban runoff reduction. The results showed that the LID measures are effective in controlling the surface runoff of the storm events with return periods shorter than five years, in particular, for one-year events. Furthermore, the effectiveness on traffic congestion mitigation of several LID measures (concave greenbelt, vegetative swales, and comprehensive measures) was evaluated. However, the effective return periods of storm events are shorter than two years if the effectiveness on traffic congestion relief is considered. In all evaluated aspects, comprehensive measures and concave greenbelts are the most effective, and vegetative swale is the least effective. This indicated that LID measures are less effective for removing ponding from most storm events in a mountainous, low-lying and backward pipeline infrastructure region with pressures from interval flooding and urban waterlogging. The engineering measures including water conservancy projects and pipeline infrastructure construction combined with the non-engineering measures were suggested to effectively control severe urban storms.

Urban rainstorm and waterlogging occurred more frequently in recent years, causing huge economic losses and serious social harms. Accurate rainstorm and waterlogging simulation is of significant value for disaster prevention and mitigation. This paper proposed a numerical model for urban rainstorm and waterlogging based on the Storm Water Management Model (SWMM) and Geographic Information System (GIS), and the model was applied in Lianhu district of Xi'an city of China. Furthermore, the effects of rainfall characteristics, pipe network implementation level and urbanization level on waterlogging were explored from the perspectives of spatial distribution of waterlogging points, drainage capacity of pipe network and surface runoff generation and confluence. The results show that: (1) with the increase of rainfall recurrence period, the peak of total water accumulating volume, the average decline rate of water accumulating volume and the number of waterlogging nodes increase; (2) optimizing the pipe diameter can shorten the average overload time of the pipe network from the entire pipe network, but for a single pipe, optimizing the pipe diameter may lead to overloading of unoptimized downstream pipeline; (3) the lower the imperviousness, the less the number of waterlogging nodes and average time of water accumulating, and (4) the west, northwest and southwest areas are relatively affected by the imperviousness, only improving the underlying surface conditions has limited influence on waterlogging in the study area. This study can provide reference for urban waterlogging prevention and reduction and pipe network reconstruction.

In recent years, with the frequent occurrence of extreme climate events and the acceleration of urbanization, the problem of urban waterlogging has become increasingly serious, which seriously threatens the safety of residents􀆳 lives and property. Urban waterlogging simulation is an important technical means for waterlogging warning and drainage system optimization. Among them, the storm water management model (SWMM) is widely used because of its open source and dynamic simulation ability. However, the model usually relies on measured hydrological data for parameter calibration, and most small and mediumsized cities are limited by monitoring facilities and lack reliable measured data, which restricts the accuracy evaluation and practical application of the model. In order to solve the above problems, this study takes the northern area of Taihe County, Anhui Province as the research area, and proposes a method for calibrating SWMM model parameters based on SAR images, which provides technical support and method reference for flood control planning and drainage facilities optimization in small and medium-sized cities. The SAR image is used to calculate the Sentinel-1 Dual-Polarized Water Index (SDWI) , and the actual submerged area is extracted by Otsu method. The parameters of the simulation results are calibrated by spatial overlap analysis, recall rate and accuracy. Using the submerged range extracted from SAR images as a verification, the recall rates of the constructed SWMM model in typical areas reached 79. 35% and 84. 69%, respectively, and the accuracy rates reached 71. 89% and 72. 53%, respectively, which verified the applicability and reliability of the model. Subsequently, the waterlogging simulation under 5-year, 10-year and 20-year return period rainfall scenarios was carried out. The simulation results revealed that with the increase of rainfall return period, the inundated area and moderate to severe water accumulation nodes in the study area increased significantly. By comparing and analyzing the spatial distribution of water accumulation range and the overload of pipe network and nodes, the characteristics of urban waterlogging and water accumulation in the study area are systematically revealed.

Investigating relationships between landscape patterns and surface runoff from a spatial distribution and intensity perspective

Method for analyzing urban waterlogging mechanisms based on a 1D-2D water environment dynamic bidirectional coupling model

近年来，越来越突出的城市内涝问题对城市排水系统规划设计提出了更高的要求。目前我国城市排水系统规划设计中仍然主要以推理公式法计算洪峰流量，同时市政排水系统的设计重现期也偏低，一旦发生较大的暴雨，便可能导致城市内涝现象的发生。本文引进在国内外得到广泛应用的计算机数学模型SWMM(Storm Water Management Model)进行武汉市典型城区的降雨径流计算。建模步骤包括利用GIS进行汇水区的划分和属性数据的提取，管网系统概化、以及参数设置。应用所构建的模型对不同降雨情景下研究区排水管网运行状况进行了模拟。结果显示，随着重现期的增加，沙湖出水口径流总量和洪峰流量增加明显，同时管网节点溢流和管道超载情况趋于严重。研究区的排水管网系统能够满足设计标准，顺利的排走1年重现期的暴雨，但是随着重现期的增加，管网性能降低明显。 With the continuing urbanization, waterlogging problems in Chinese cities become more and more prominent, thus putting big pressures on the urban drainage network. In the urban drainage system design in China, the design recurrence interval of rainfall is often set to be very low, thus urban waterlogging can easily happen once big heavy rainstorm happens. Also, traditional rational formula method is still widely used to calculate peak flow from rainfall. This article introduces a hydrological model package named SWMM to simulate the rainfall-runoff processes in a typical urban region, named the Chu rivulet, in Wuhan city. Major steps of applying models include the use of GIS to discretize the study area into a number of sub-drainage areas and the extract of the attribute information for each sub-drainage area, the drainage network generalization, and the parameters setting and calibration. In order to analyze the operation conditions of the drainage system, the established model is applied in the study area under the rainfall scenarios with different frequencies. The results show that with the increase of recurrence interval of rainfall, the total runoff and peak flow at the Chu rivulet outlet increase, and the surcharging of the drainage network becomes more and more serious. It is concluded that the designed drainage system can drain away rainwater with recurrence interval of 1 year, but with the increase of recurrence interval of rainfall, the performance of drainage system degrades significantly.

In recent years, ultra-high-intensity rainfall at home and abroad has caused frequent urban waterlogging disasters, posing a severe threat to people’s lives, property and city’s safety. Based on the satellite image data of Shanghai Waigaoqiao Free Trade Zone in different periods and the Storm Water Management Model (SWMM), this paper establishes a model of heavy rainfall under the underlying surface of a complex city, and analyses topographic features, different land use types, rainfall infiltration intensity and the characteristics of the drainage pipe network. The rainwater accumulation under different rainstorms and urbanization levels is simulated and analysed. The research results show that urban rainstorm accumulation is closely related to land use changes. With the increase of surface impermeability and rainfall intensity, the risk of waterlogging in the study area tends to increase: From 1994 to 2019, the construction area has increased from 2.5096km2 to 5.8662km2 in the study area. Compared with 1994, under the same rainfall conditions, the simulated flooding node and runoff coefficient in 2019 both increased significantly.

Urban waterlogging frequently occurs in semi-humid areas due to the short duration of heavy rainfall in summer and the high rates of subsurface hardening caused by high-intensity urban development. To solve the problem of urban waterlogging, China has launched the construction of ‘sponge cities’ and made some progress, but there is still a lack of comprehensive consideration of the functional types and spatial layout of low impact development (LID) facilities. Qian'an, a city of Hebei Province, is one of the first sponge city pilot cities in China. This paper focuses on Yanshan South Road and its surrounding areas, a historical waterlogging section of Qian'an city. Four common LID measures (sunken green space (SG), bioretention ponds (BP), infiltration ponds (IP), and reservoirs (RE)) in two function types are selected and combined through centralized (CE) and decentralized (DE) different spatial layouts, a total of 80 design scenarios are proposed. Then, using the storm water management model (SWMM) to calculate the effect of each scheme on peak flow reduction under different rainfall return periods. The results showed that all LID scenarios can effectively alleviate the urban waterlogging problem, among which the schemes of DE-SG-BP (1:1), DE-IP-SG (1:1), DE-SG-IP (3:1), DE-SG-IP (1:3), and DE-SG-BP (3:1) had the highest peak flow reduction rate, up to 95.46%. The schemes of CE-RE-IP (3:1) and CE-IP-RE (3:1) had better hydrological performance in occupying less surface space, with a peak flow reduction rate of 8.68% per square meter. Therefore, the distributed layout combined with infiltration LID facilities and storage LID facilities can be used in urban built-up areas with limited land use conditions, which has a more obvious effect on reducing waterlogging.