Flood Storage Area Research Articles

Analysis of Flood Storage Area Operations in Huai River Using 1D and 2D River Simulation Models Coupled with Global Optimization Algorithms

This article addresses the issue of flood management using four flood storage areas in the middle section of Huai River in China which protect the important downstream city of Bengbu. The same areas are also used by the local population as residential and agricultural zones. An optimization problem is therefore posed, with two objectives of simultaneously minimizing the downstream flood risk in Bengbu city and the storage areas’ economic damages. The methodology involved development of river flood models using HEC-RAS, with varying complexity, such as 1-dimensional (1D) model with storage areas represented as lumped conceptual reservoirs, and 2-dimensional (2D) models with detailed representation of the terrain, land-use and hydrodynamics in the storage areas. Experiments of coupling these models with global optimization algorithms (NSGA-II, PESA-II and SPEA-II) were performed (using the HEC-RAS Controller), in which the two objective functions were minimized, while using stage differences between the river and the storage areas as decision variables for controlling the opening/closing of the gates at the lateral structures that link the river with the storage areas. The comparative analysis of the results indicate that more refined optimal operational strategies that spread the damages across all storage areas can be obtained only with the detailed flood simulation models, regardless of the optimization algorithm used.

Systemic Flood Risk Management: The Challenge of Accounting for Hydraulic Interactions

Rivers typically flow through multiple flood-protected areas which are clearly interconnected, as risk reduction measures taken at one area, e.g., heightening dikes or building flood storage areas, affect risk elsewhere. We call these interconnections ‘hydraulic interactions’. The current approach to flood risk management, however, neglects hydraulic interactions for two reasons: They are uncertain and, furthermore, considering them would require the design of policies not only striving for risk reduction, but also accounting for risk transfers across flood-protected areas. In the present paper, we compare the performance of policies identified according to the current approach with those of two alternative formulations: One acknowledging hydraulic interactions and the other also including an additional decision criterion to account for equity in risk distribution across flood-protected areas. Optimal policies are first identified under deterministic hydraulic interactions, and, next, they are stress-tested under uncertainty. We found that the current approach leads to a false sense of equal risk distribution. It does, however, perform efficiently when a risk-averse approach towards uncertain hydraulic interactions is taken. Accounting for hydraulic interactions in the design of policies, instead, increases efficiency and both efficiency and equity when hydraulic interactions are considered deterministically and as uncertain, respectively.

A catchment partnership approach to delivering natural flood management in the Evenlode, UK

Adapting to climate change and its impacts on water resources is one of the major challenges facing the UK. In the first scheme of its kind in the Thames basin, this paper describes how natural flood management (NFM) is being piloted in the Littlestock Brook tributary of the Evenlode catchment. This 5-year scheme (2016–2021) explores the delivery mechanisms and assesses the effectiveness of NFM measures to reduce flood risk in Milton-under-Wychwood, improve water quality and create habitat. It has secured £640 000 from Environment Agency programmes, the Thames Regional Flood and Coastal Committee, other partners and landowners. In 2018, ten field corner bunds were created with a combined storage capacity of 26 000 m3. Woody dams in the brook divert high flows into these flood storage areas. Critical to success is integrated delivery through the Evenlode Catchment Partnership and engagement of the local community. Catchment partnerships deliver a range of environmental, social and economic benefits, and directly support many of the ambitions under the government’s 25-Year Environment Plan and the Water Framework Directive. Collaborative working with Thames Water, the Department for Environment, Food and Rural Affairs, consultants and academics has enabled the project to utilise existing delivery mechanisms and to model and monitor the effectiveness of NFM.

A flood mitigation control strategy based on the estimation of hydrographs and volume dispatching

Abstract Flood events are expected more frequent with biggest magnitude in the near future. They have potential big impacts on human economic activity and property, on health and life of man, and on the environment. One possibility to mitigate the flood impact consists in using flood storage areas and in designing a control strategy to dispatch the volumes of water and reducing the flow peak. The designed mitigation control strategy is based on the prediction of hydrographs and the estimation of the water volumes that have to be stored. It leads to optimal flow peak reduction according to the capacity of the flood storage areas. This paper details the steps of the proposed approach. Then, a realistic case-study is considered to illustrate the designed flood mitigation control strategy.

Identifying ecological red lines in China’s Yangtze River Economic Belt: A regional approach

‘Ecological red lines’ (ERL) is currently used as a national policy for protecting ecological systems for sustainable development and safeguarding ecological security. The ERL defines the scale and scope of ecosystem services, and can be applied in policy decision-making and ecological protection. This study employs three ecological models (InVEST, RUSLE, CASA) and uses GIS to consolidate five key indicators (annual available recharge, soil retention capacity, net primary productivity, protected areas, lakes and flood storage and retention areas) that measure ecosystem services and two ecological vulnerability indicators (susceptibility of geological hazards, rocky desertification) to establish a coherent framework and criteria of the ERL. The ERL is spatially delineated in China’s Yangtze River Economic Belt on the regional scale. The results show that the total area of ERL amounts to 1.13 million km2, accounting for 55.5% of the total land area within the Belt. Six ERL domains—biodiversity conservation and soil retention; soil retention; biodiversity conservation; water conservation; soil retention and carbon sequestration; and biodiversity conservation and water conservation— make up 82.8% of the total ERL. The findings suggest that implementation of ERL policy is effective when the regional authority acts as an independent and a third-party assessor and enforces the use of a cross-provincial ecological compensation strategy. The coherent framework and criteria of the ERL at the regional scale is applicable to other regions of China.

Extracting Farmland Features from Lidar-Derived DEM for Improving Flood Plain Delineation

Flood plains, which are commonly distributed in flat river or lake basins, often contain large tracts of farmland. Therefore, flood plains require precise and detailed information on the role played by farmland in flood routing simulations, flood risk evaluation, and flood loss evaluation. In farmland, cultivated land parcels are not directly adjacent. The intervening non-cultivable land, which might include trails and ditches, can cover large areas. Currently, the area of non-cultivable land between cultivated land parcels is usually measured by artificial visual interpretation or by fieldwork. This study focused on the extraction of uncultivable trails, ditches, and cultivated field parcels within farmland on the basis of a Light Detection and Ranging-derived (LiDAR-derived) high-resolution gridded Digital Elevation Model (DEM). The proposed approach was applied to generate polygons of individual land parcels in a flood storage and detention area. The DEM was first smoothed and then subtracted. To remove small spots and to smooth the boundaries of the land parcels, inner and outer buffers were created to generalize the extracted polygons. Experiments proved that this approach is applicable in flood plain farmland and demonstrated that the chosen parameters were appropriate. This approach is more efficient than traditional surveying methods. For field parcel extraction, the accuracy achieved was 93.42%, using official statistics for comparison, and the Cohen’s kappa coefficient was 0.90, using a visual interpretation of an aerial image for comparison. The kappa coefficients were 0.87 and 0.77 for trail and ditch extraction, respectively.

Research and evaluation of water pollution in Lake Wabu Basin, Huaihe Catchment

瓦埠湖位于淮河中游南岸，属于淮河流域最大的湖泊.根据2011年8月-2015年12月对瓦埠湖湖区3个监测点位、入（出）湖河流4个监测断面的水质监测数据，选用内梅罗水污染指数法和单因子指数法，以总氮、总磷、铵态氮和高锰酸盐指数为评价指标对瓦埠湖湖区水体和主要入（出）湖河流水质现状进行评价，结果表明：瓦埠湖湖区总体水质状况为轻度污染、Ⅳ类水质，其主要污染源为农业面源污染和生活污染；部分入湖河流受农业氮、磷污染的影响水质较差，其中庄墓河污染情况最为严重.因此，必须加强流域的水环境综合整治工作，控制农业面源污染对流域水环境的影响.;Lake Wabu, as the largest lake in the Huaihe Catchment, is located on south bank of the middle-reach Huaihe River and serves as a flood storage area in this basin. To eliminate influence of countryside domestic sewage, this paper is to evaluate the water quality based on data at three monitoring sites and four monitoring sections in the Lake Wabu, which data were obtained during a period from October in 2011 to December in 2015. The pollution factors were analyzed by utilizing methods of the single factor pollution evaluation and the Nemerow pollution index with evaluation indicators of permanganate index, total nitrogen, total phosphorus and ammonium nitrogen. The conclusions are as follows. Water in the Lake Wabu is slightly polluted with the Grade Ⅳ, and its main pollution comes from the sources of agriculture and daily life in the basin. Some inflow rivers already are of bad water quality with abundant nitrogen and phosphorus, in which Zhuangmu River is the worst. It is necessary to renovate the basin environment comprehensively and control the effect of the agricultural non-point pollution.

Comparison of Three Different Parallel Computation Methods for a Two-Dimensional Dam-Break Model

Three parallel methods (OpenMP, MPI, and OpenACC) are evaluated for the computation of a two-dimensional dam-break model using the explicit finite volume method. A dam-break event in the Pangtoupao flood storage area in China is selected as a case study to demonstrate the key technologies for implementing parallel computation. The subsequent acceleration of the methods is also evaluated. The simulation results show that the OpenMP and MPI parallel methods achieve a speedup factor of 9.8× and 5.1×, respectively, on a 32-core computer, whereas the OpenACC parallel method achieves a speedup factor of 20.7× on NVIDIA Tesla K20c graphics card. The results show that if the memory required by the dam-break simulation does not exceed the memory capacity of a single computer, the OpenMP parallel method is a good choice. Moreover, if GPU acceleration is used, the acceleration of the OpenACC parallel method is the best. Finally, the MPI parallel method is suitable for a model that requires little data exchange and large-scale calculation. This study compares the efficiency and methodology of accelerating algorithms for a dam-break model and can also be used as a reference for selecting the best acceleration method for a similar hydrodynamic model.

Parallel Computation of a Dam-Break Flow Model Using OpenACC Applications

AbstractTwo key factors in dam-break modeling are accuracy and speed. Therefore, high-performance calculations are of great importance to the simulation of dam-break events. In this study, we develop a two-dimensional hydrodynamic model based on the finite volume method to simulate the dam-break flow routing process. Roe’s approximate Riemann solution is adopted to solve the interface flux of grid cells and accurately simulate the discontinuous flow. A graphics processing unit (GPU)-based parallel method, OpenACC, is used to realize parallel computing. Because an explicit discrete technique is used to solve the governing equations, and there is no correlation between grid calculations in a single time step, the parallel dam-break model can be easily realized by adding OpenACC directives to the loop structure of the grid calculations. To analyze the performance of the model, we considered the Pangtoupao flood storage area in China using a Nvidia Tesla K20c card and four different grid division schemes. By ...

Learning for improvement

Learning for improvement

Integration of 2-D hydraulic model and high-resolution lidar-derived DEM for floodplain flow modeling

Abstract. The rapid progress of lidar technology has made the acquirement and application of high-resolution digital elevation model (DEM) data increasingly popular, especially in regards to the study of floodplain flow. However, high-resolution DEM data pose several disadvantages for floodplain modeling studies; e.g., the data sets contain many redundant interpolation points, large numbers of calculations are required to work with data, and the data do not match the size of the computational mesh. Two-dimensional (2-D) hydraulic modeling, which is a popular method for analyzing floodplain flow, offers highly precise elevation parameterization for computational mesh while ignoring much of the micro-topographic information of the DEM data itself. We offer a flood simulation method that integrates 2-D hydraulic model results and high-resolution DEM data, thus enabling the calculation of flood water levels in DEM grid cells through local inverse distance-weighted interpolation. To get rid of the false inundation areas during interpolation, it employs the run-length encoding method to mark the inundated DEM grid cells and determine the real inundation areas through the run-length boundary tracing technique, which solves the complicated problem of connectivity between DEM grid cells. We constructed a 2-D hydraulic model for the Gongshuangcha detention basin, which is a flood storage area of Dongting Lake in China, by using our integrated method to simulate the floodplain flow. The results demonstrate that this method can solve DEM associated problems efficiently and simulate flooding processes with greater accuracy than simulations only with DEM.

Flood risk control of dams and dykes in middle reach of Huaihe River

Three stochastic mathematical models for calculation of the reservoir flood regulation process, river course flood release, and flood risk rate under flood control were established based on the theory of stochastic differential equations and features of flood control systems in the middle reach of the Huaihe River from Xixian to the Bengbu floodgate, comprehensively considering uncertain factors of hydrology, hydraulics, and engineering control. They were used to calculate the flood risk rate with flood regulation of five key reservoirs, including the Meishan, Xianghongdian, Nianyushan, Mozitan, and Foziling reservoirs in the middle reach of the Huaihe River under different flood frequencies, the flood risk rate with river course flood release under design and check floods for the trunk of the Huaihe River in conjunction with relevant flood storage areas, and the flood risk rate with operation of the Linhuaigang Project under design and check floods. The calculated results show that (1) the five reservoirs can withstand design floods, but the Xianghongdian and Foziling reservoirs will suffer overtopping accidents under check floods; (2) considering the service of flood storage areas under the design flood conditions of the Huaihe River, the mean flood risk rate with flood regulation of dykes and dams from Xixian to the Bengbu floodgate is about 0.2, and the trunk of the Huaihe River can generally withstand design floods; and (3) under a check flood with the flood return period of 1 000 years, the risk rate of overtopping accidents of the Linhuaigang Project is not larger than 0.15, indicating that it has a high flood regulation capacity. Through regulation and application of the flood control system of the Linhuigang Project, the Huaihe River Basin can withstand large floods, and the safety of the protected area can be ensured.

Development of Louth flood alleviation scheme outline design

The market town of Louth (in Lincolnshire), on the River Lud, has suffered from flooding on many occasions, most recently in 2007. Atkins was commissioned to conduct a feasibility study into the potential for a flood defence scheme. This paper begins once the preferred option of two online flood storage areas had been identified; the brief from this point was to develop their outline design. Atkins worked closely with a contractor to develop a cost estimate for the works and to ensure buildability was considered. The two dams are designed as homogenous earth fill embankments, with heights of circa 6 m, and retaining a combined volume of 213 000 m3 (during a flood event); both storage areas fall under the requirements of the Reservoirs Act 1975. As in many cases, these reservoirs present particular challenges; designed to be empty for the majority of their life, they are required to meet the needs of a variety of stakeholders. The design was further complicated by the risk of unexploded ordnance and burrowing animals. This paper presents the outline design under three sections: the location, embankments and control structures. For each section the paper discusses the alternatives considered, the selection process and the adopted design.

The Land Use/Cover Change in Flood Storage and Detention Area Based on RS: A Case Study of the LaoWangPo Flood Storage and Detention Area in the Huaihe River Valley

The dynamic monitoring of detention basin land use/cover change and the comprehensive grasp of the detention basin land use structure and degree are of great significance to the scientific and rational use and development of the detention basin. The three periods of Landsat TM / ETM + data (1999, 2005,2010) of the LaoWangPo detention basin are used to analysis and calculate land use/cover change of the LaoWangPo detention basin from 1999 to 2010 , the single land use dynamic degree and the land use/cover change transition matrix, and to calculate the detention basin land use extent change indicators. Studies have shown that the LaoWangPo land use structure and strength have undergone a significant change during the 12 years, and are still in a development and change period.

Parallel computation of a dam-break flow model using OpenMP on a multi-core computer

High-performance calculations are of great importance to the simulation of dam-break events, as discontinuous solutions and accelerated speed are key factors in the process of dam-break flow modeling. In this study, Roe’s approximate Riemann solution of the finite volume method is adopted to solve the interface flux of grid cells and accurately simulate the discontinuous flow, and shared memory technology (OpenMP) is used to realize parallel computing. Because an explicit discrete technique is used to solve the governing equations, and there is no correlation between grid calculations in a single time step, the parallel dam-break model can be easily realized by adding OpenMP instructions to the loop structure of the grid calculations. The performance of the model is analyzed using six computing cores and four different grid division schemes for the Pangtoupao flood storage area in China. The results show that the parallel computing improves precision and increases the simulation speed of the dam-break flow, the simulation of 320 h flood process can be completed within 1.6 h on a 16-kernel computer; a speedup factor of 8.64× is achieved. Further analysis reveals that the models involving a larger number of calculations exhibit greater efficiency and a higher rate of acceleration. At the same time, the model has good extendibility, as the speedup increases with the number of processor cores. The parallel model based on OpenMP can make full use of multi-core processors, making it possible to simulate dam-break flows in large-scale watersheds on a single computer.

Analysis of Inflow Design Flood for Liujiaxia Reservoir under Dynamic Operation of Flood Limited Water Level for Ten-Day Period

the layout and the characteristics of the cascade reservoirs and hydropower stations in the upper reaches of the Yellow River, determine that cascade hydropower stations scheduling must be operated based on the joint operation between Longyangxia and Liujiaxia cascade hydropower stations, especially on flood control operation. This paper deeply analyzes design flood storage area of the Liujiaxia composition and Longyangxia-Liujiaxia joint flood regulating principle on the basis of analyzing and calculating each ten-day design flood of the Tangnaihai above main stream and the intervals. Therefore, the reasonable combination of interval flood and the process of Longyangxia reservoir flood discharge is confirmed, and thereby, studying Liujiaxia reservoir inflowing design flood under a controlling operation of flood limited water level for a period of ten-day to ensure the safety of Liujiaxia reservoir flood control.

Water management in the Fens before the introduction of pumps

ABSTRACT Much has been written about the seventeenthcentury draining of the (peat) Fens debouching into The Wash but there are some persistent misunderstandings and also issues on which information is lacking. Some of the main issues relate to: relationships between drainage and navigation; management of water levels; and the antecedents of the scheme undertaken by Cornelius Vermuyden from 1649. These uncertainties are additional to the over-riding lesson of this enterprise, that the peat Fens as a whole could not be drained successfully in the absence of pumps, initially windmills, to lift water over waterway embankments to compensate for shrinkage of the peat once drained. These lessons enable us the better to appreciate the achievements of the Anglo-Saxons and their successors in defending the silt lands and modifying the channel network in the peat areas; much of this network modification was apparently for transport purposes, the peat lands acting as a vast flood storage area. From the mid-thirteenth century, Commissions of Sewers were established in response to disasters and the failure of customary maintenance arrangements; these Commissions reflect the scale and sophistication of the inherited infrastructure but we do not know how the works had originally been organised and executed.

Sustaining Sherman Island: A Water Management and Agricultural Diversification System

The Sacramento-San Joaquin River Delta isthe main water resource for California’s urbanand agricultural development. Sherman Islandsits on the western edge of Delta system and isone of the key geographic features in balancingthe flux of saltwater into the Delta. Flooding,saltwater intrusion, and ongoing subsidence arecurrent threats to Sherman Island. The integrationof components of aquaculture, hydroponics, anda levee enclosed flood storage area create a system that can actively protect against flooding disastersby reversing subsidence and stabilizing levees, hasthe ability to sequester carbon and restore habits,and the capacity to produce economic yields. Theenvironmental, technical, and economic attributesof the system are examined through failuresimulations, economic analysis, and environmentdiscussion to determine if the proposed system isa feasible, sustainable and profitable solution forSherman Island and the Delta.Sustaining Sherman Island: A Water Management andAgricultural Diversification System

Modelling river-floodplain interaction during flood propagation

The (re)integration of flood storage areas in the river system is considered and proved as an effective flood protection measure. By their (controlled) filling and emptying, inundation risks for downstream areas with higher vulnerability can be reduced. They have an influence not only on the flood level, but also on the residence time of the water in the river ecosystem, which is an important biological parameter. A good prediction of storage flow is therefore necessary in an integrated ecosystem model. In such a model, which is being developed by the universities of Ghent and Antwerp, hydraulic, biological and biogeochemical processes are coupled. In this paper, a one-dimensional hydrodynamic module of the integrated STRIVE (STReam RIVer Ecosystem) model, which is based on the de Saint–Venant equations and solved by the Preissmann scheme, is adapted to be able to include flow exchange with storage cells. This model is validated with experimental laboratory measurements on a small scale. The flow between the storage cells and the river is controlled by weirs (flooded river banks). Model simulations with STRIVE are also compared with HEC-RAS simulations. Good agreement between simulations of both models and between the STRIVE simulations and the measurements is found.

Concept for land use based on regular inundation in the contemplated flood storage areas above Szeged (HUNGARY)

The planned improvements on the Vásárhelyi plan propose the setting up of flood storage areas along the banks of the Hungarian section of the River Tisza. Two main options have been outlined to transform the land-use system of these areas. According to the first option, the present land-use system with a dominant ratio of arable lands would remain and land-users would receive compensation if the land was used for flood control. The second option suggests a change in the structure of land use to establish a system involving regular inundation in these areas. In this case not only extremely high water levels but all floods would be led out onto these flood storage areas. One of the most important conditions for the introduction of this scenario is the flood regime of the River Tisza. This paper analyses the characteristics of this flood regime as it affects the planned flood storage area to be built near Szeged in southern Hungary on an area of approximately 6000 hectares between Baks, Ópusztaszer and Dóc. The statistics predict that the occurrence and duration of the floods could make the regular inundation of this area possible, but the fact that the water often recedes relatively rapidly may necessitate the partial retention of the floods.