水口水库拦洪蓄满度影响因素分析与对策探讨

本文通过采用排列图法对水口水库年均汛末拦洪蓄满度低的影响因素进行分析,得出洪水预报误差大和库水位回蓄时机偏迟的两大影响因素,进而制定人工修正洪水预报模块和增加控制判别条件对策,提高水口水库的拦洪蓄满度,实现洪水资源的科学利用。     

Design hydrograph and routing scheme for flood mapping in a dense urban area

Definition of flood risk maps is a task to which modern surface hydrology devotes substantial research effort. Their impact on the management of flood-prone, dense, urban areas has increased the need for better investigation of inundation dynamics. The problems associated with the aforementioned topics range from the definition of the design hydrograph and the identification of the surface boundary conditions for the flood routing over the inundation plan, to the choice of the hydrodynamic model to simulate urban flooding. Most of academic and commercial mathematical models, solving the De Saint Venant equations, fail on complex topography. Frequently encountered difficulties concern steep slopes, geometric discontinuities, mixed flow regimes, and initially dry areas. In the present paper, flood routing modelling approaches in urban areas and principles for the definition of the design flood events are outlined. The paper shows how urban flooding can be simulated by a quasi-2D hydrodynamic model that makes use of a network of connected channels and storages to simulate flow, respectively, on the streets and into the building blocks. Furthermore, the paper shows that, when flood hazard is assessed by considering flood extent, water depth and flow velocity, an in-depth analysis of the use of design hydrographs that maximise peak flow or inundation volume is needed.     

Application of surrogate artificial intelligent models for real‐time flood routing

Developing a robust flood forecasting and warning system (FFWS) is essential in flood‐prone areas. Hydrodynamic models, which are a major part of such systems, usually suffer from computational instabilities and long runtime problems, which are particularly important in real‐time applications. In this study, two artificial intelligence models, namely artificial neural network (ANN) and adaptive neuro‐fuzzy inference system (ANFIS), were used for flood routing in an FFWS in Madarsoo river basin, Iran. For this purpose, different rainfall patterns were transformed to run‐off hydrographs using the Hydrologic Engineering Center (HEC)‐1 hydrological model and routed along the river using HEC river analysis system RAS hydrodynamic model. Then, the simulated hydrographs with different lag times were used as inputs for training of ANN and ANFIS models to simulate flood hydrograph at the basin outlet. Results showed that the simulations obtained from ANN and ANFIS coincided with the results simulated by the HEC‐RAS, and application of such models is strongly suggested as a backup tool for flood routing in FFWSs.     

Validating a rapid assessment framework for screening surface water flood risk

This research evaluates performance of a rapid assessment framework for screening surface water flood risk in urban catchments. Recent advances in modelling have developed fast and computationally efficient cellular automata frameworks which demonstrate promising utility for increasing available evidence to support surface water management, however, questions remain regarding trade‐offs between accuracy and speed for practical application. This study evaluates performance of a rapid assessment framework by comparing results with outputs from an industry standard hydrodynamic model using a case study of St Neots in Cambridgeshire, UK. Results from the case study show that the rapid assessment framework is able to identify and prioritise areas of flood risk and outputs flood depths which correlate above 97% with the industry standard approach. In theory, this finding supports a simplified representation of catchments using cellular automata, and in practice presents an opportunity to apply the framework to develop evidence to support detailed modelling.     

Application of spatial statistics as a screening tool for sustainable flood retention basin management

In the context of climate change and the EU flood directive, this paper analyses and explores sustainable flood retention basins (SFRB) as adaptive structures contributing to water resources management and flood risk control. A dataset of 371 potential SFRB (including many operating reservoirs) characterized by 40 variables have been surveyed across central Scotland. However, the spatial properties of these SFRB, such as water storage (which relates to flooding depth) in different regions, are ambiguous. This paper uses geostatistics on the Scottish dataset. Spatial analysis showed that ordinary kriging, which is a spatial interpolation method, could be successfully applied to estimate numerical values for all key flood control variables everywhere in the study area. Moreover, the probability that certain threshold values relevant to flood control managers were exceeded can also be calculated by using disjunctive kriging. The findings provide an effective screening tool in assessing flood control using SFRB.     

Validation of 2D shock capturing flood models around a surcharging manhole

This work offers a detailed validation of finite volume (FV) flood models in the case where horizontal floodplain flow is affected by sewer surcharge flow via a manhole. The FV numerical solution of the 2D shallow water equations is considered based on two approximate Riemann solvers, HLLC and Roe, on both quadrilateral structured and triangular unstructured mesh-types. The models are validated against a high resolution experimental data-set obtained using a physical model of a sewer system linked to a floodplain via a manhole. It was verified that the sensitivity of the models is inversely proportional to the surcharged flow/surface inflow ratio, and therefore requires more calibration from the user especially when concerned with localised modelling of sewer-to-floodplain flow. Our findings provide novel evidence that shock capturing FV-based flood models are applicable to simulate localised sewer-to-floodplain flow interaction.     

Learning from the extreme River Tyne flood in January 2005

Extreme floods often demonstrate unanticipated characteristics that pose problems for management and response. The floods on the Tyne and Eden in January 2005 provided numerous examples of such unexpected response. This paper describes characteristics of storm rainfall and runoff generation on the River Tyne catchment, flood effects and damage. Unusual aspects of hydrological behaviour are highlighted as a basis for assessing what lessons can be learned for flood risk management. These include problems associated with coincidence of extreme wind speeds and rainfall, the retarding influence of floodplain storage on flood wave travel time in extreme flows, the influence of critical storm duration on the severity of the resulting flood on headwaters and main river, and the variety of mechanisms of flood occurrence. The occurrence of such an extreme flood provides the opportunity to validate and enhance the review process of the Environment Agency's flood zone maps.     

北京平谷盆地地下储水空间雨洪资源利用方式分析

近年来,地下储水空间雨洪资源利用作为开展雨洪资源化、缓解水资源紧张状况的有效途径日益受到广泛关注。本文以北京平谷盆地为例,在充分分析水文地质条件的基础上,采用指标叠加的方法评价了该地区开展地下储水空间雨洪资源利用的适宜性,并讨论了以平谷盆地为代表的北方半湿润山前冲洪积地区利用腾空的地下储水空间实现雨水资源化的途径和方法。     

提高大坝安全性能的一种方法——溢洪道维修案例分析(英文)

瑞典新的洪水设计及大坝安全指南对全国水库大坝的安全提出了更高的要求。指南对每一条河流情况进行了复核并找到了较好的解决方案,即储水和提高溢洪道泄洪能力相结合的方案。为了符合指南的要求,瑞典全国上下都在实施一个大坝安全计划,对大量的水库大坝提高其安全性能,以满足更高的洪水设计(及其它方面)的要求。技术方案包括大坝加固、溢洪道泄洪能力提升和临时储水设施。Stenkullafor 水库大坝设有一个 2 闸控制的敞开式溢洪道。该水库修改后的设计洪水将比现有溢洪道泄洪能力提高 40%。根据成本效益分析,提高溢洪道泄流能力的主要措施是降低其中一个闸门顶高程,以适应需要提高的泄洪能力。通过水工模型试验,一方面优化溢洪道顶部轮廓,另一方面降低溢洪道顶部改造和新闸门的成本。溢洪道右侧闸门底高程降低 4.3 m,并新安装一扇更高的闸门。现在,大坝的安全性能已得到提高。对水工模型试验和施工时的洪水风险,施工过程及其遇到的困难进行了介绍,并对坝体加固、上游坡新的侵蚀防护、下游消能及下游行洪渠道等工程措施进行了描述。     

Records of pan (floodplain wetland) sedimentation as an approach for post-hoc investigation of the hydrological impacts of dam impoundment: The Pongolo river, KwaZulu-Natal

River impoundment by dams has far-reaching consequences for downstream floodplains in terms of hydrology, water quality, geomorphology, ecology and ecosystem services. With the imperative of economic development, there is the danger that potential environmental impacts are not assessed adequately or monitored appropriately. Here, an investigation of sediment composition of two pans (floodplain wetlands) in the Pongolo River floodplain, KwaZulu-Natal, downstream of the Pongolapoort dam constructed in 1974, is considered as a method for post-hoc assessment of the impacts on river hydrology, sediment supply and water quality. Bumbe and Sokhunti pans have contrasting hydrological regimes in terms of their connection to the main Pongolo channel - Bumbe is a shallow ephemeral pan and Sokhunti is a deep, perennial water body. The results of X-ray fluorescence (XRF) geochemical analysis of their sediment records over a depth of >1 m show that whilst the two pans exhibit similar sediment composition and variability in their lower part, Bumbe pan exhibits a shift toward increased fine-grained mineral supply and associated nutrient influx at a depth of c. 45 cm whilst Sokhunti pan is characterised by increased biogenic productivity at a depth of c. 26 cm due to enhanced nutrient status. The underlying cause is interpreted as a shift in hydrology to a ‘post-dam’ flow regime of reduced flood frequencies with more regular baseline flows which reduce the average flow velocity. In addition, Sokhunti shows a greater sensitivity to soil influx during flood events due to the nature of its ‘background’ of autochthonous biogenic sedimentation. The timing of the overall shift in sediment composition and the dates of the mineral inwash events are not well defined, but the potential for these wetlands as sensitive recorders of dam-induced changes in floodplain hydrology, especially those with a similar setting to Sokhunti pan, is clearly demonstrated.     

River Thames Flood Hydrology Design Curves

A quick method of defining design peak flows and hydrographs for any point on the River Thames between Days weir and Teddington is offered as a design tool for flood analysis. This paper presents the findings of a flood frequency and flood hydrograph analysis for the River Thames. The results were used in a hydraulic analysis of the river and its floodplain at Reading, but showed a wider application of the method on the river.     

Flash flooding in Spain: geomorphological approaches supporting flood frequency analysis, and the implications for the design of structures

Conventional methods for the estimation of flood frequency are generally based on the statistical analysis of data series resulting from the measurement of water levels at specific locations, which are translated into discharges (m³/s) using standard stage/discharge relationships. Subsequently, these gauged flows are used to identify the largest flood event experienced by a river or catchment, and to produce growth curves used in the estimation of the return periods of specific flood events, as well as in the calculation of discharges for specific required design events (e.g. return period 1 in 100 year). In areas where gauging data records are scarce, and/or the data series are short or interrupted, geomorphological interpretation of the physical environment, dating of fluvial deposits and flooding episodes and hydraulic reconstruction of past flood events can be used as complementary tools aiding conventional hydrological and flood frequency analysis methods. This paper will discuss the undertaking of this approach in the Guadalope Catchment in northeast Spain. It will examine the findings in relation to the inadequate design of existing structures such as dams, spillways, canals and reservoirs, and will also look at the potential risks associated with flooding at present.     

增强现实技术于洪水风险沟通中的应用

气候变迁,特别是洪水问题给地处三角洲的城市带来了与日俱增的风险。作为应对手段,提出一种整合性的洪水风险管理方法,该方法确保了洪水风险沟通在洪水风险管理战略中的重要地位。洪水的可视化作为洪水风险沟通的一种工具,在改变人们对洪水风险的观念方面有着强大的作用。它可以通过互动的方式,使当地的利益相关者了解洪水的剩余风险和未来风险。其中增强现实技术作为一种可视化手段,它的快速发展与应用为风景园林设计、规划与教育等领域提供了崭新的交互方式。首先,探讨增强现实技术(AR)在洪水风险沟通中的应用现状,并重点关注增强现实技术的2个关键应用领域:对现场决策的支持和针对高层次设计的可视化与对景观干预的评估。随后,展示一种基于增强现实技术所开发的应用,该款创新性的应用为洪水风险沟通提供了一种轻量化的可视化手段。     

The current state of the use of large wood in river restoration and management

Trees fall naturally into rivers generating flow heterogeneity, inducing geomorphological features, and creating habitats for biota. Wood is increasingly used in restoration projects and the potential of wood acting as leaky barriers to deliver natural flood management by ‘slowing the flow’ is recognised. However, wood in rivers can pose a risk to infrastructure and locally increase flood hazards. The aim of this paper is to provide an up‐to‐date summary of the benefits and risks associated with using wood to promote geomorphological processes to restore and manage rivers. This summary was developed through a workshop that brought together academics, river managers, restoration practitioners and consultants in the UK to share science and best practice on wood in rivers. A consensus was developed on four key issues: (i) hydrogeomorphological effects, (ii) current use in restoration and management, (iii) uncertainties and risks and (iv) tools and guidance required to inform process‐based restoration and management.     

Floodplain nutrient and sediment dynamics on the Kent Stour

Floodplain land use is currently of concern. Agri‐environmental policy favours grass over arable agriculture, while urban development is deemed unsuitable. The role of meadowland requires evaluation because it exhibits a potential to deliver environmental goods beyond flood detention and habitat creation; it has the potential to take up particular elements and trap sediment. This is particularly important where there is eutrophication of water from agriculture and wastewater and also physical degradation of the channel and floodplain. In this study, carbon (C), nitrogen and phosphorus (P) status and sediment deposition at typical locations on a southern English floodplain were investigated. It is concluded that C sequestration could be significant and there is sediment trapping during times of flood but further P accumulation in the topsoil of grazing land is limited. It is concluded that nutrient loading of the river from sewage effluent and from agriculture is best prevented at source.     

Accuracy of the ISIS bridge methods for prediction of afflux at high flows

This paper presents the experimental results and findings from investigation into the accuracy, capability and suitability of the ISIS software package to model flow through bridge structures. Different types of bridge models, in terms of soffit shape, set in a two‐stage channel with various roughness conditions, were used for this study. In order to simulate natural environmental conditions, the original experimental data were scaled up using the undistorted‐scale method. One‐dimensional ISIS bridge methods, the ARCH bridge method, USBPR bridge method and the Bernoulli loss unit, were applied to both original experimental data and the scaled‐up data. The results for the ARCH bridge method and the USBPR method of ISIS are significantly different from the measured data and the Bernoulli loss unit. The Bernoulli loss unit, which uses Bernoulli's equation in ISIS, is the most accurate method to compute the afflux of bridges in waterways.     

论21世纪的城市防洪减灾

本文回顾了 1980年代以后我国洪涝灾害愈演愈烈的情况 ,提出规划师和建筑师可以在城市和新城区选址、保护和利用城市水体、增大城区蓄水容量、规划设计建筑适洪系统等四个方面为 2 1世纪的城市防洪减灾作出贡献。     

Flood-Plain Mapping of the River Leam and River Itchen

As part of the requirements of s. 105 of the Water Resources Act 1991, the Environment Agency is producing flood-plain maps of all major rivers. Where no historic data are available for a large flood event, mathematical models are used to simulate 100-year design flood flow events, which allows the definition of flood-prone areas. These maps, together with a database of the water levels and flows, will form part of a national Flood Plain Information System.
This paper describes the development and generation of flood-plain maps for the Rivers Leam and Itchen in Warwickshire. The data collection and review of topographic and hydrometric data are outlined. Procedures for combining information from gauged data, historical flood data and methods based on catchment characteristics form the basis for estimating design input flows to hydraulic models. Modelling principles and data requirements of two different hydraulic models, used to estimate peak water levels of design return period, are described.     

Calibrated methodology for assessing climate change adaptation costs for urban drainage systems

Changes in precipitation patterns associated with climate change may pose significant challenges for storm water management systems across the U.S. In particular, adapting these systems to more intense rainfall events will require significant investment, though no method currently exists for estimating the costs of these investments on a national scale. To support assessment of these costs at the national level, this paper presents a reduced-form approach for estimating changes in normalized flood depth (the volume of node flooding normalized by the area of the catchment) and the associated costs of flood prevention. This reduced form approach is calibrated to results generated by the U.S. Environmental Protection Agency's Storm Water Management Model (SWMM) for city-wide or neighborhood-level catchments in seven cities across the U.S. Estimates derived from this approach represent a reasonable approximation of storm water management adaptation costs and exhibit no systematic bias relative to results derived from SWMM.     

与洪水和谐相处——科学发展观指导下的城市防洪规划

结合新一轮济南市城市总体规划——城市防洪规划的编制,探讨了基于科学发展观编制城市防洪规划的热点问题:一是合理利用土地,即城市建设不与洪水争地;二是确定城市防洪标准时必须合理与适度,不应一味地追求所谓的高标准,而城市除涝标准应大幅度提高;三是强调雨洪资源化利用,将雨洪灾害转变为资源;四是变堵为疏,重视滞蓄洪区的规划,给洪水以出路;五是河道治理采用生态型河道,体现由以往的改造自然转变为回归自然、顺应自然的治理理念;六是广泛利用防洪非工程措施。