Spatial diversion and coordination of flood water for an urban flood control project in Suzhou, China

Suzhou City,located in the Yangtze River Delta in China,is prone to flooding due to a complex combination of natural factors,including its monsoon climate,low elevation,and tidally influenced position,as well as intensive human activities.The Large Encirclement Flood Control Project(LEFCP)was launched to cope with serious floods in the urban area.This project changed the spatiotemporal pattern of flood processes and caused spatial diversion of floods from the urban area to the outskirts of the city.Therefore,this study developed a distributed flood simulation model in order to understand this transition of flood processes.The results revealed that the LEFCP effectively protected the urban areas from floods,but the present scheduling schemes resulted in the spatial diversion of floods to the outskirts of the city.With rainstorm frequencies of 10.0%to 0.5%,the water level differences between two representative water level stations(Miduqiao(MDQ)and Fengqiao(FQ))located inside and outside the LEFCP area,ranged from 0.75 m to 0.24 m and from 1.80 m to 1.58 m,respectively.In addition,the flood safety margin at MDQ and the duration with the water level exceeding the warning water level at FQ ranged from 0.95 m to 0.43 m and from 4 h to 22 h,respectively.Rational scheduling schemes for the hydraulic facilities of the LEFCP in extreme precipitation cases were developed ac-cording to food simulations under seven scheduling scenarios.This helps to regulate the spatial flood diversion caused by the LEFCP during extreme precipitation.

基于MIKE FLOOD模型的平原水网地区内涝治理效果模拟研究

为科学评估平原水网地区内涝治理效果,以昆山市淀山湖镇为研究对象,基于MIKE FLOOD模型,耦合一维河网、二维地形和一维管网模拟了平原水网地区城镇内涝情况。采用实测降雨数据对模型进行了率定和验证,并模拟了2年一遇、5年一遇、10年一遇和20年一遇4种重现期降雨条件下现状和治理后的最大淹没水深。模拟结果表明:20年一遇降雨条件下内涝范围变化明显,其余3种重现期降雨条件下内涝范围变化不明显;对于降雨重现期较小条件下的城市内涝治理,应优先考虑管网改造,而针对短历时的强暴雨事件,应优先考虑海绵城市设施建设改造;为了应对不同重现期、短历时降雨造成的城市内涝风险,应在管网改造的基础上配合海绵城市设施建设改造。

Exploration of Sponge System Design in Wetland Parks Based on Rainwater and Flood Control: A Case Study of Southern Anhui Province

Based on the background that wetland resources in China are under threat and urgently need to be protected,a series of rainwater and flood problems caused by urban construction is analyzed comprehensively,and the design and planning methods of wetland parks in response to rainwater and flood disasters caused by floods and heavy rainfall are explored.Southern Anhui with complex and variable terrain and frequent rainfall and flood disasters is selected as the research area,with Xuanzhou District of Xuancheng City as the main research object.The relationship between municipal drainage of urban park and water conservancy drainage is investigated from different sample selection,design samples,and design flow rates.Based on literature review and model building methods,an urban storm flood model suitable for typical wetland parks in southern Anhui is constructed after processing the survey data using Arc GIS,SWMM(storm water management model).On this basis,a methodology and principles for designing a sponge system of wetland park based on rainwater and flood control are proposed,including technical measures such as rainwater collection,retention,and purification.This paper provides certain research results in design schemes,effect evaluations,ecological and social benefits,and useful suggestions and solutions for urban stormwater management and resilience development.

基于MIKE FLOOD的城市小流域内涝防治能力评估

文章以广州市鹤洞涌小流域为研究对象,基于MIKE FLOOD构建了水动力耦合模型,模拟不同重现期降雨条件下流域内涝情况,对城市内涝防治能力进行评估,提出治理方案。研究结果表明,降雨强度的增大会使城区低洼地的内涝风险加剧,通过城市竖向优化、区域海绵化改造、水务工程建设等措施,可有效提高区域内涝防治能力。耦合模型能较好的评估区域内涝防治能力,为城市治涝提供一定的参考。

ON THE HYDRAULIC FAILURE PROBABILITY OF FLOOD CONTROL DAMS

In flood control dams it is not only the failure to prevent flood larger than their design carrying capacity, but also the uncertainties of hydraulic factors that cause disasters. In general, the hydraulic risk is not considered in most of the hydrological analysis in floodproofing plan and design. In this paper, a method of evaluating the hydraulic risk is developed by employing risk theory, and the concept can easily be extended to other types of risk analysis. As a result, it is possible not to consider the hydraulic resks when the design hydrologic risk of flood control dam is lger. Otherwise, the hydraulic risks must be noticed. The research is very helpful for the development of the flood control theory used at present.

Application of Computer Simulation in the Reservoir Flood Control

[Objective] To discuss the application of simulation technique in preliminary solution of reservoir flood control of.[Method] Based on the study of river system simulation theory,the InfoWorks RS system was adopted to build a digital analog model for flood routing in certain river system and the flood discharge was analyzed with the check criterion.[Result] The flood information system based on InfoWorks RS simulated the inundation of downstream during flood discharge and drew mutation pictures to indicate how hydraulic parameters of maximum runoff at each control section,runoff of each control section and flow velocity varied with time,how hydraulic elements mutated with time as well as the most likely inundated area analysis of lower reservoir.[Conclusion] To provide references for reducing serious loss caused by flood and making out preliminary solution to flood control.

CO_2-triggered gelation for mobility control and channeling blocking during CO_2 flooding processes

CO2 flooding is regarded as an important method for enhanced oil recovery （EOR） and greenhouse gas control. However, the heterogeneity prevalently dis- tributed in reservoirs inhibits the performance of this technology. The sweep efficiency can be significantly reduced especially in the presence of ＂thief zones＂. Hence, gas channeling blocking and mobility control are important technical issues for the success of CO2 injection. Normally, crosslinked gels have the potential to block gas channels, but the gelation time control poses challenges to this method. In this study, a new method for selectively blocking CO2 channeling is proposed, which is based on a type of CO2-sensitive gel system （modified polyacry- lamide-methenamine-resorcinol gel system） to form gel in situ. A CO2-sensitive gel system is when gelation or solidification will be triggered by CO2 in the reservoir to block gas channels. The CO2-sensitivity of the gel system was demonstrated in parallel bottle tests of gel in N2 and CO2 atmospheres. Sand pack flow experiments were con- ducted to investigate the shutoff capacity of the gel system under different conditions. The injectivity of the gel system was studied via viscosity measurements. The results indi- cate that this gel system was sensitive to CO2 and had good performance of channeling blocking in porous media. Advantageous viscosity-temperature characteristics were achieved in this work. The effectiveness for EOR in heterogeneous formations based on this gel system was demonstrated using displacement tests conducted in double sand packs. The experimental results can provide guideli- nes for the deployment of theCO2-sensitive gel system for field applications.

Hydrological adjustment and flooding control of wetlands in the Liaohe Delta

The function of estuary wetland on hydrological adjustment and flooding control is studied in this paper. It is estimated that the evapotranspiration in the reed field during growth season(June to October) is 722.9 mm, which is 37.5% higher than large water body(E 601∶525.9 mm). The water replacement rate in the reed field can reach 95% only when the rains continuously for 11 days and the precipitation reached 912 mm. For the water balance in the paddy field, the total water requirement ranges between 1920 and 1860 mm, among which, 31% is from precipitation, and the left is provided by reservoirs. The water usage efficiency is 0.35 at present productivity. Based on the landscape characteristics and functionalities on flooding control, 5 functional zones are designed for the Liaohe Delta: key protected area; underground storage area; flooding discharge area; flood diversion area in emergency; and flood control drainage area.

Potential control of climatic changes on flood events in the Yangtze Delta during1100-2002

Wide collection on the historic records of the climatic changes and flood events is performed in the Yangtze Delta. Man-Kendall (MK) method is applied to explore the changing trends of the time series of the flood discharge and the maximum high summer temperature. The research results indicate that the flood magnitudes increased during the transition from the medieval warm interval into the early Little Ice Age. Fluctuating climate changes of the Little Ice Age characterized by arid climate events followed by the humid and cold climate conditions give rise to the frequent flood hazards. Low-lying terrain made the study region prone to the flood hazards, storm tide and typhoon. MK analysis reveals that the jumping point of the time series of the flood discharge changes occurred in the mid-1960s, that of the maximum summer temperature changes in the mid-1990s, and the exact jump point in 1993. The flood discharge changes are on negative trend before the 1990s, they are on positive tendency after the 1990s; the maximum high summer temperature changes are on negative trend before the 1990s and on positive tendency after the 1990s. These results indicate that the trend of flood discharge matches that of the maximum high summer temperature in the Yangtze Delta. The occurrence probability of the maximum high summer temperature will be increasing under the climatic warming scenario and which will in turn increase the occurrence probability of the flood events. More active solar action epochs and the higher sea surface temperature index (SST index) of the south Pacific Ocean area lying between 4 o N-4 o S and 150 o W-90 o W correspond to increased annual precipitation, flood discharge and occurrence frequency of floods in the Yangtze Delta. This is partly because the intensified solar activities and the higher SST index give rise to accelerated hydrological circulation from ocean surface to the continent, resulting in increased precipitation on the continent.

An Improved Contract Net Protocol with Multi-Agent for Reservoir Flood Control Dispatch

Contract Net Protocol (CNP) has been widely used in solving the problems of multi-Agent cooperates and reservoir flood control optimization dispatch. This paper designs an Agent functional module based on the multi-Agent coordinated the construction of reservoir flood control optimization dispatch and the corresponding Agent to solve the problem of classical CNP in the Agent communication aspect, to enhance the efficiency of reservoir optimization dispatch and to improve the insufficiency of the classical CNP in the application of reservoir flood control dispatcher. Then, the capacity factor and the cooperation level are introduced in the module. Experiments are conducted on the Agentbuilder simulation platform to simulate reservoir flood control optimization dispatching with the improved CNP. The simulation results show the communication interactive efficiency and the performance of new protocol is superior to those of the classical CNP.

Using modified Soil Conservation Service curve number method to simulate the role of forest in flood control in the upper reach of the Tingjiang River in China

To improve flood control efficiency and increase urban resilience to flooding,the impacts of forest type change on flood control in the upper reach of the Tingjiang River(URTR) were evaluated by a modified model based on the Soil Conservation Service curve number(SCS-CN) method. Parameters of the model were selected and determined according to the comprehensive analysis of model evaluation indexes. The first simulation of forest reconstruction scenario,namely a coniferous forest covering 59.35km^2 is replaced by a broad-leaved forest showed no significant impact on the flood reduction in the URTR. The second simulation was added with 61.75km^2 bamboo forest replaced by broad-leaved forest,the reduction of flood peak discharge and flood volume could be improved significantly. Specifically,flood peak discharge of 10-year return period event was reduced to 7-year event,and the reduction rate of small flood was 21%-28%. Moreover,the flood volume was reduced by 9%-14% and 18%-35% for moderate floods and small floods,respectively. The resultssuggest that the bamboo forest reconstruction is an effective control solution for small to moderate flood in the URTR,the effect of forest conversion on flood volume is increasingly reduced as the rainfall amount increases to more extreme magnitude. Using a hydrological model with scenarios analysis is an effective simulation approach in investigating the relationship between forest type change and flood control. This method would provide reliable support for flood control and disaster mitigation in mountainous cities.

Oil Production Optimization by Means of a Combined“Plugging,Profile Control,and Flooding”Treatment:Analysis of Results Obtained Using Computer Tomography and Nuclear Magnetic Resonance

Due to long-term water injection,often oilfields enter the so-called medium and high water cut stage,and it is difficult to achieve good oil recovery and water reduction through standard methods(single profile control and flooding measures).Therefore,in this study,a novel method based on“plugging,profile control,and flooding”being implemented at the same time is proposed.To assess the performances of this approach,physical simulations,computer tomography,and nuclear magnetic resonance are used.The results show that the combination of a gel plugging agent,a polymer microsphere flooding agent,and a high-efficiency oil displacement agent leads to better results in terms of oil recovery with respect to the situation in which these approaches are used separately(the oil recovery is increased by 15.37%).Computer tomography scan results show that with the combined approach,a larger sweep volume and higher oil washing efficiency are obtained.The remaining oil in the cluster form can be recovered in the middle and low permeability layer,increasing the proportion of the columnar and blind end states of the oil.The nuclear magnetic resonance test results show that the combined“plugging,profile control,and flooding”treatment can also be used to control more effectively the dominant channels of the high permeability layer and further expand the recovery degree of the remaining oil in the pores of different sizes in the middle and low permeability layers.However,for the low permeability layer(permeability difference of 20),the benefits in terms of oil recovery are limited.

Urban flood control strategy based on new relationship of human and flood

China is one of the countries with the most serious flooding disasters.In China,above 70% of big cities,50% of population and 75% of industrial and agricultural output value are distributed in eastern coastal areas with serious flooding.Therefore,enhancement of theoretical study and experience summarization of urban flood control is of great theoretical and practical significance.As economy is developing rapidly,urban scale is expanding fast,and urban flood control stand is promoted.Urban flood control calls for new concept and methods.This paper makes a systematic summarization of concept evolution and advanced methods concerning urban flood control at home and abroad.The concept of urban flood control has transformed from simple flood control and drainage to coexistence with and use of flood.Flood control measures have transferred form emphasis upon engineering ones to priority to both engineering and non-engineering ones,with special attention to ecological flood control,such as making full use of ecological revetment,ecological realignment of a river,multi-objective management of urban flood detention region,turning flood into resources and utilization of wetlands.

New Challenges and Opportunities for Flood Control in the Huai River: Addressing a Changing River-Lake Relationship

This paper addresses the change of the river-lake relationship in the Huai River and its causes due to environmental change and human activities. A preliminary analysis is made from three aspects: (1) the natural geographical change particularly captured by the Yellow River, (2) water conservancy project construction, and (3) socioeconomic development in the Huai River Basin. Key problems of changes in this river-lake relationship and the Huai River flood control are tackled, involving flood control and disaster alleviation ability of the Basin, engineering and non-engineering measurements applied to flood control and disaster mitigation, and water governance for adaptive management. Research shows that the Huai River is a rather complex one due to its complex geography with a hybrid wet and dry climate zoon, and higher population density. With the alternation of the river-lake relationship and socioeconomic development in the region, new problems keep arising, imposing new requirements on its sustainable water management. Thus, understanding the Huai River is a long and gradually improving process. Its future planning should keep absorbing new achievements of science and technology development, employing new technologies and methods, and gradually deepening our understanding of its fundamental principles. Water governance and adaptive water management will be new challenges and opportunities for the Basin in its river system change and flood control.

Preliminary Study in Spatial Data Warehouse of Flood Control and Disaster Mitigation in Yangtze River Basin

Since 1990s,the spatial data warehouse technology has rapidly been developing, but due to the complexity of multi-dimensional analysis, extensive application of the spatial data warehouse technology is affected. In the light of the characteristics of the flood control and disaster mitigation in the Yangtze river basin, it is proposed to design a scheme about the subjects and data distribution of the spatial data warehouse of the flood control and disaster mitigation in Yangtze river basin, i.e., to adopt a distributed scheme. The creation and development of the spatial data warehouse of the flood control and disaster mitigation in Yangtze river basin is presented .The necessity and urgency of establishing the spatial data warehouse is expounded from the viewpoint of the present situation being short of available information for the flood control and disaster mitigation in Yangtze river basin.

The Effect of Geologic Structures on the Control of Floods in the Middle Yangtze River Valley

This paper discusses the role of geologic structures in the occurrence of floods and how to prevent flood in the middle reaches of the Yangtze River, and gives the author's suggestion that the Luoshan Qiakou be expanded and the land reclaimed from Dongting Lake be returned to the lake in compliance with the law of geology.

Effect of Flood Peak Discharge Control by a Small Reservoir in an Urbanized Area—Case Study in the Kurabe River Basin, Japan

Recently severe damage of flooding by urbanization was frequently occurred. To prevent this damage, small reservoir was constructed in the urbanized residential area. This paper describes an effect of flood peak discharge control by a small reservoir (control reservoir) caused by rapidly developed urbanization. Although work for this purpose was conducted, research on the effects of the control reservoir was not conducted until now. This research, conducted by simulation, was a case study in the Kurabe River Basin in the Tedori River Alluvial Fan Area, Japan, based on the precise investigation of the reservoir in the actual field. The study was conducted to determine not only the actual control reservoir capacity for the newly developed residential area but also the ideal capacity for all present residential areas and the largest capacity allowable for a maximum rainfall event that recently occurred. The control reservoir effects between individual blocks and the entire basin area were compared by dividing the test basin into 15 blocks (sub-basins). The results showed that the effects on the capacity per unit area of the residential area in blocks have close relationship with the decreasing ratio of peak discharge in blocks. Consequently, the effects of control reservoir capacity and the limitation were clarified. In the future, control reservoirs should be constructed for all of the already developed residential areas, for example, by utilizing underground car parking lot. The results of this research can contribute to the design of the control reservoir for protection against flooding damage in urbanized areas.

FLOOD CONTROL PROGRAMME IN BANGLADESH

Bangladesh locates in lower reach of Ganges-Brahmaputra-Meghma, Bengal delta. Bangladesh is a land of rivers and heavy monsoon rains. Every year during monsoon period (May-September)the country floods of verying magnitude, it causes damages to crops, properties, infrastructures, etc. and ultimately affects the economy development of the country. Banglandesh flood has some features given below: 1. The excessive rainfall over the vast catchment area of the river is the main cause of flood in Bangladesh, but 90% of the flood carried by rivers come from outside the country, i.e. regional countries, India, Nepal,

Decision Support System for Flood Control with Applications to Jiangxi Province

Affected by the climatic fluctuation and human activities, significant changes of the flood control situation are taking place in China. In the new century, the flood control systems have to face a series of challenges. In this paper, we design fa decision support system (DSS) for flood control based on its requirements. The DSS has been applied to decision-making for flood control in Jiangxi province, and play an important role in the flood control in the recent two years. Finally, we plot the further improvement on the DSS so that it will make more contribution in the flood control.

Methodological Proposition of an Integrated System for Urban Floods Control

In the State of Santa Catarina, Brazil, especially in the Itajai valley, there are records of accidents and disasters mainly associated to landslides and floods, which have caused significant damages and losses, including human lives. In order to make the coexistence with such natural disasters possible, most particularly with floods, a integration is required among the technical, political, environmental, and human knowledge. Measures that encompass integrated actions for the entire river basin, with the help from an updated technical cadastre and tools, such as the GIS, allow the development of planning tools that might effectively help the people to live with the water, or else to cope with floods in a more appropriate manner. This paper attempts to propose a methodology for urban flood control, based on the integration among the several public entities involved in the flood control, along with the CTM （Multipurpose Technical Cadastre） and GIS tool. In order to solve or minimize the problems, the model proposed here aims at promoting a balance between the agents involved, and enables to rank the degrees of importance assigned to the different needs, thus allowing to eliminate or to improve those areas and processes that are duplicated or superimposed.