Flood Management Strategies Research Articles

Planning for climate change in a flood‐prone community: municipal barriers to policy action and the use of visualizations as decision‐support tools

AbstractEfforts are intensifying to design effective flood management strategies that account for a changing climate and that make use of the wealth of resources and latent capacities associated with action at the local level. Municipalities, however, are subject to a host of challenges and barriers to action, revealing the critical need for sophisticated participatory processes in support of municipal decision‐making under conditions of considerable uncertainty. This paper examines a new process for envisioning local climate change futures, which uses an iterative, collaborative, multistakeholder approach to produce computer‐generated 3‐dimensional images of climate change futures in the flood‐prone municipality of Delta, British Columbia, Canada. The process appeared to forge communicative partnerships, which may improve the legitimacy and effectiveness of the flood management and climate change response discourse in the municipality of Delta, and may lead to locally specific and integrated flood management and climate change response strategies. We concluded that, while an enabling context and normative pressures are clearly integral to effective action, so too is the type and mode of presentation of information about climate futures.

A novel flood management strategy to plan eco-industry development in areas of coastal land-subsidence in Taiwan

Because of limited freshwater resources, urban and industrial areas in Taiwan are often given priority for allocation of water resources. Accordingly, residents in rural regions usually pump groundwater for irrigation and daily needs. Continuous land subsidence has resulted in the elevation of the ground surface to be lower than the sea level, which has led to frequent flooding and created wetland habitats. In addition, seawater intrusion has damaged the soil, which has made the land difficult to farm. This study proposes a novel concept called the Island Lake Eco-town Program that would send the surface runoff from stormwater into a flood buffer wetland through land elevation modification and the necessary levee construction. Except for the use of stormwater to leach salt from the soil, we propose growing salt tolerant crops. Yunlin County of Taiwan has been selected as a study area to evaluate the feasibility of the proposed method. This study also demonstrated how to evaluate the available production of rice growth in saline soils.

Flood Management Strategies in Frequent and Small Scale Events: Lessons Learned from Amarante (Portugal)

Flood Management Strategies in Frequent and Small Scale Events: Lessons Learned from Amarante (Portugal) The 2000/2001 winter was exceptionally rainy in Portugal and between November 2000 and March 2001 several floods occurred. In this period some localities registered the highest floods of the last hundred years. One example is the town of Amarante, in the north of Portugal, that has been affected by several flood events during the time frame previously mentioned. There is no reference of these episodes in the international disaster databases (e.g. Em-data, Darmouth Flood Observatory) because it is a very small scale event, and no fatalities were recorded. However, it is a recurrent situation with considerable direct and indirect damages which affects a small part of the cultural heritage centre which is also an important touristic and commercial area. The objective of this paper is to understand the characteristics of flood risk in Amarante which is a product of the hazard and the vulnerability of exposed elements (e.g. people, environment and structures) in order to improve flood disaster management efficiency. The paper is organized into two parts. On the first one we add new data to the previous knowledge through the identification of flood episodes in two time periods, between 1937 and 1955 and from 1985 to 2001. Each event was characterized according to several parameters (e.g. flood peak, water height, flooding area, duration, and flow velocity) and classified into six levels according to flood magnitude (water height), flooded area (extension) and potential impacts (damages). This approach improves hazard knowledge and systematizes emergency response procedures. It can improve the communication, not only between the different civil protection agents, but also between them and the citizens during the emergency. It can also be useful for assurance companies' policy. The second part is focused on the management of the March 21st 2001 flood which was the most severe in Amarante's history at least in the last hundred years. Understanding the damages and the impacts of flood on livelihoods, the emergency procedures, as well as the articulation between people and civil protection agents are fundamental to increase the efficiency of flood risk management strategies and the determination of appropriate protection levels.

Living in hazardous waterscapes: Gendered vulnerabilities and experiences of floods and disasters

Considerable literature exists on floods and weather-related disasters, but limited attention has been given to the varied social implications of hazards in the lives of people, especially from a gender perspective. This is particularly poignant in floodplains and coastal areas, where water is a key element in giving, sustaining and taking away life and livelihood. Critical social and geographical analyses enable better understanding of the ways hazardous waterscapes are perceived, experienced and negotiated by people across social categories in their everyday life. This article attempts to highlight the gendered and classed coping strategies and adaptation measures that men and women engage with (that both challenge and reproduce social relations and vulnerabilities) in their attempts to survive in hazardous environments. Drawing from an analysis of the gendered dynamics of floods and disasters as well as the interventions that were undertaken via the Flood Action Plan in Bangladesh, I demonstrate the differential and gendered implications of both water-related hazards and the structural interventions that were envisioned to address the hazards. With climate change likely to exacerbate floods and disasters, it is important to heed such differentiations and marginalizations, so as to draw insights to better inform current and future adaptation approaches, flood management and disaster management strategies.

On the use of 1D and coupled 1D-2D modelling approaches for assessment of flood damage in urban areas

Urban flooding has become an increasingly important problem and a growing social issue around the world. Since it continues to be regarded as an almost inevitable danger, the development of cost-effective flood management strategies has become of the utmost importance for many cities, and particularly for those cities in developing countries where the financial resources for recovery from flood-related disasters are almost nonexistent. As a consequence, there is nowadays a range of modelling approaches available for modelling floods and developing flood management strategies. Typically, one-dimensional (1D) hydrodynamic models are used as a standard industry practice. More recently, however, model formulations have included a 1D representation of the main channels and a 2D representation of the floodplains. Since the physical process of describing exchanges of flows with the floodplains can be represented in different ways, the predictive capability of the different modelling approaches can also vary. The present paper explores the difference in predictive capabilities of 1D and 1D-2D modelling approaches for the purpose of urban flood analysis across irregular terrains. It is shown, as expected, that in the case of terrains suited to exclusively 1D models the prediction of flow variables along the channel can be realistic, but that, when it comes to the projection onto a 2D map, the representation of the terrain topography together with the mapping techniques that are employed introduce a limiting factor in their successful application. Practical implications of these two modelling approaches are analysed and illustrated on a case study from St Maarten, NA. The results of this study provide users of numerical models with information that can be used to aid them in determining which tool to use and which aspects to consider in order to make more reliable analyses of flooding processes in urban areas.

Time series modeling and forecast of river flow

Changing climate, human interventions to natural water flow pattern, haphazard urbanization etc., are the reasons for intense flood even after development of so many structural measures of overflow control. Kulfo River basin is situated in relatively dry southern area of the Ethiopia and is still under geographical modification with hilly topography and impervious soil texture. The concern of the present research is to simulate flood episode in order to develop flood management strategies to reduce disaster. The complexicity of natural hydrological phenomenon and dependent random variables can be better expressed considering it as stochastic process. Flood (maximum river flow) forecasting on the Kulfo River with monthly runoff data using stochastic ARIMA, Time Series model was developed for warning purposes. The analysis of seasonally varying time series of discharge data has revealed that a higher order ARIMA model may produce excellent results for three to six months forecast.

Combination of different types of ensembles for the adaptive simulation of probabilistic flood forecasts: hindcasts for the Mulde 2002 extreme event

Abstract. Flood forecasts are essential to issue reliable flood warnings and to initiate flood control measures on time. The accuracy and the lead time of the predictions for head waters primarily depend on the meteorological forecasts. Ensemble forecasts are a means of framing the uncertainty of the potential future development of the hydro-meteorological situation. This contribution presents a flood management strategy based on probabilistic hydrological forecasts driven by operational meteorological ensemble prediction systems. The meteorological ensemble forecasts are transformed into discharge ensemble forecasts by a rainfall-runoff model. Exceedance probabilities for critical discharge values and probabilistic maps of inundation areas can be computed and presented to decision makers. These results can support decision makers in issuing flood alerts. The flood management system integrates ensemble forecasts with different spatial resolution and different lead times. The hydrological models are controlled in an adaptive way, mainly depending on the lead time of the forecast, the expected magnitude of the flood event and the availability of measured data. The aforementioned flood forecast techniques have been applied to a case study. The Mulde River Basin (South-Eastern Germany, Czech Republic) has often been affected by severe flood events including local flash floods. Hindcasts for the large scale extreme flood in August 2002 have been computed using meteorological predictions from both the COSMO-LEPS ensemble prediction system and the deterministic COSMO-DE local model. The temporal evolution of a) the meteorological forecast uncertainty and b) the probability of exceeding flood alert levels is discussed. Results from the hindcast simulations demonstrate, that the systems would have predicted a high probability of an extreme flood event, if they would already have been operational in 2002. COSMO-LEPS showed a reasonably good performance within a lead time of 2 to 3 days. Some of the deterministic very short-range forecast initializations were able to predict the dynamics of the event, but others underpredicted rainfall. Thus a lagged average ensemble approach is suggested. The findings from the case study support the often proposed added value of ensemble forecasts and their probabilistic evaluation for flood management decisions.

Dealing with Uncertainty in Flood Management Through Diversification

Aerts, J. C. J. H., W. Botzen, A. van der Veen, J. Krywkow, and S. Werners. 2008. Dealing with uncertainty in flood management through diversification. Ecology and Society 13(1): 41. https://doi.org/10.5751/ES-02348-130141

Urban Managed Realignment: Application to the Thames Estuary, London

Over the centuries, London has progressively encroached into the tidal Thames River as it has developed into a “World City”. This encroachment has exacerbated the flood risk to new and adjacent land, despite continual upgrading of flood defences. The pressure for further encroachment remains, despite the new threat of human-induced climate change—that is, the combined effect of (1) increased peak river flow in the winter, (2) more intense precipitation events, (3) accelerated sea-level rise, and possibly (4) more severe storms and resulting storm surges. Costly upgrade of defences is inevitable to manage the increased flood risk, and this has caused a re-evaluation of the Thames Estuary's flood defence program. For the first time, managed realignment in urban areas is being considered as a flood management tool. This offers a range of potential benefits including (1) increasing storage for floodwater, (2) improving ecological functioning, (3) improving riverside access for people, and (4) reversing the long-term trend of encroachment into the river. Planned managed realignment can widen the scope for future defence upgrade, but has been limited in urbanised areas. Several projects in London (e.g., Tate Modern and Millennium Dome) have shown that realignment can achieve the benefits described above, which supports the government's recent “Making Space for Water” policy.This study investigates the feasibility of managed realignment in the Thames Estuary. Fragmentation between flood defence and spatial development policies, lack of political support, and riverside encroachment continue to delay urban realignment projects. Successful application will require long-term planning (over decades) that exploits all opportunities for landward realignment offered by redevelopment. With the uncertainties behind climate change and more development in the “Thames Gateway”, further research is needed to understand the contribution of urban realignment to any flood management strategy that may be applied to other coastal urban areas.

Early warning and flood forecasting for large rivers with the lower Mekong as example

An early warning system is a set of procedures designed to protect human lives and minimize damages to be expected from a flood which exceeds a certain critical level. It consists of a number of related and connected parts: forecasting, transformation of the forecast into a warning, transmission of the warning to local decision makers, conversion of the warning into remedial action (UN/ISDR, 2004). Each of these components must work efficiently for a successful early warning system. In developing countries such a system is of particular importance for saving human lives. The components of an early warning system will be described first, and details will be given for designing a data based flood forecasting model, using the lower Mekong as example. The example draws on the Flood Mitigation and Management Strategy of the Mekong River Commission (MRC) for the lower Mekong countries.

Developing a GIS based integrated approach to flood management in Trinidad, West Indies

Trinidad and Tobago is plagued with a perennial flooding problem. The higher levels of rainfall in the wet season often lead to extensive flooding in the low-lying areas of the country. This has lead to significant damage to livestock, agricultural produce, homes and businesses particularly in the Caparo River Basin. Clearly, there is a need for developing flood mitigation and management strategies to manage flooding in the areas most affected. This paper utilizes geographic information systems to map the extent of the flooding, estimate soil loss due to erosion and estimate sediment loading in the rivers in the Caparo River Basin. In addition, the project required the development of a watershed management plan and a flood control plan. The results indicate that flooding was caused by several factors including clear cutting of vegetative cover, especially in areas of steep slopes that lead to sediment filled rivers and narrow waterways. Other factors include poor agricultural practices, and uncontrolled development in floodplains. Recommendations to manage floods in the Caparo River Basin have been provided.

High-Resolution 3-D Flood Information From Radar Imagery for Flood Hazard Management

This paper presents a remote-sensing-based steady-state flood inundation model to improve preventive flood-management strategies and flood disaster management. The Regression and Elevation-based Flood Information eXtraction (REFIX) model is based on regression analysis and uses a remotely sensed flood extent and a high-resolution floodplain digital elevation model to compute flood depths for a given flood event. The root mean squared error of the REFIX, compared to ground-surveyed high water marks, is 18 cm for the January 2003 flood event on the River Alzette floodplain (G.D. of Luxembourg), on which the model is developed. Applying the same methodology on a reach of the River Mosel, France, shows that for some more complex river configurations (in this case, a meandering river reach that contains a number of hydraulic structures), piecewise regression is required to yield more accurate flood water-line estimations. A comparison with a simulation from the Hydrologic Engineering Centers River Analysis System hydraulic flood model, calibrated on the same events, shows that, for both events, the REFIX model approximates the water line reliably

A framework for evaluation of flood management strategies

The resulting impact of disasters on society depends on the affected country's economic strength prior to the disaster. The larger the disaster and the smaller the economy, the more significant is the impact. This is clearest seen in developing countries, where weak economies become even weaker afterwards. Deliberate strategies for the sharing of losses from hazardous events may aid a country or a community in efficiently using scarce prevention and mitigation resources, thus being better prepared for the effects of a disaster. Nevertheless, many governments lack an adequate institutional system for applying cost effective and reliable technologies for disaster prevention, early warnings, and mitigation. Modelling by event analyses and strategy models is one way of planning ahead, but these models have so far not been linked together. An approach to this problem was taken during a large study in Hungary, the Tisza case study, where a number of policy strategies for spreading of flood loss were formulated. In these strategies, a set of parameters of particular interest were extracted from interviews with stakeholders in the region. However, the study was focused on emerging economies, and, in particular, on insurance strategies. The scope is now extended to become a functional framework also for developing countries. In general, they have a higher degree of vulnerability. The paper takes northern Vietnam as an example of a developing region. We identify important parameters and discuss their importance for flood strategy formulations. Based on the policy strategies in the Tisza case, we extract data from the strategies and propose a framework for loss spread in developing and emerging economies. The parameter set can straightforwardly be included in a simulation and decision model for policy formulation and evaluation, taking multiple stakeholders into account.

From structures to sustainability: a history of flood management strategies in Canada

Four principles are identified as being associated with sustainability balance, ecosystem approach, adaptive management and teamwork. The evolution of flood management strategies in Canada is provided using secondary historical sources. The sustainability of flood management in Canada is assessed in terms of the nature and extent to which flood management strategies exhibit principles of balance, ecosystem approaches, adaptive management and teamwork. The paper concludes that while Canada's National Disaster Mitigation Strategy (NDMS) has made progress towards achieving sustainability, there are specific considerations that require further attention.

Flood-risk mapping: contributions towards an enhanced assessment of extreme events and associated risks

Abstract. Currently, a shift from classical flood protection as engineering task towards integrated flood risk management concepts can be observed. In this context, a more consequent consideration of extreme events which exceed the design event of flood protection structures and failure scenarios such as dike breaches have to be investigated. Therefore, this study aims to enhance existing methods for hazard and risk assessment for extreme events and is divided into three parts. In the first part, a regionalization approach for flood peak discharges was further developed and substantiated, especially regarding recurrence intervals of 200 to 10 000 years and a large number of small ungauged catchments. Model comparisons show that more confidence in such flood estimates for ungauged areas and very long recurrence intervals may be given as implied by statistical analysis alone. The hydraulic simulation in the second part is oriented towards hazard mapping and risk analyses covering the whole spectrum of relevant flood events. As the hydrodynamic simulation is directly coupled with a GIS, the results can be easily processed as local inundation depths for spatial risk analyses. For this, a new GIS-based software tool was developed, being presented in the third part, which enables estimations of the direct flood damage to single buildings or areas based on different established stage-damage functions. Furthermore, a new multifactorial approach for damage estimation is presented, aiming at the improvement of damage estimation on local scale by considering factors like building quality, contamination and precautionary measures. The methods and results from this study form the base for comprehensive risk analyses and flood management strategies.

Planning and management of flood damage control: the South African experience

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Flood Management Strategy for the Upper and Middle Odra River Basin: Feasibility Study of Raciborz Reservoir

The river Odra, which rises in the Czech Republic and disgorges into the Baltic, suffered an extreme flood in July 1997 which was responsible for the loss of 55 lives and over a billion dollars worth of damage in southern Poland. The return period of the flood is variously estimated between 250 and 1000 years. The paper describes the hydrological and hydraulic studies undertaken for a flood reservoir (storage capacity is approximately 180,000,000 m3) to be constructed on the River Odra just upstream the ancient town of Raciborz, on the border between Poland and Czech Republic. These studies included the hydrodynamic modelling of a 220 km stretch of the river down to the city of Wroclaw where most of the damage occurred, flood damage analysis with and without the proposed reservoir, sensitivity analysis of operating rules for Nysa reservoirs and improvement of flood control capacity of existing channels and polders. Cost-benefits analysis, environmental impact assessments and resettlement plans, in addition to the engineering studies of the dam itself, were also carried out during the project stage but have not been included in the present paper.

FLOOD MANAGEMENT IN THE LOWER INCOMATI RIVER BASIN, MOZAMBIQUE: TWO ALTERNATIVES

The aim of this paper is to compare two views of flood management and thus add to the present thinking of living with floods as opposed to the traditional approach of flood control. The traditional pathway has widely been adopted in developed countries and aims to control floodwaters by means of dams and dikes. The alternative pathway tends towards a policy whereby society lives with the floods by being prepared and having the right damage reduction measures in place. In this paper two pathways are tentatively compared for the Lower Incomati Basin, Mozambique. In the design cultural theory is considered, as is how the design of each path may look according to different management perspectives. The Lower Incomati Basin provides an interesting case study as it is in a relatively undeveloped state. Hence, it is an ideal area for conducting research into the application of alternative flood management strategies. The preliminary results suggest that both pathways are feasible. However, considering recent hydrological extremes such as the 2000 floods, the resilient pathway may ultimately be a more appealing flood management strategy.

Sustainable development of floodplains (SDF) project

Abstract The sustainable development of floodplains (SDF) project is an EU-funded, trans-national co-operation between Germany and The Netherlands that deals with flood prevention and nature development along the river Rhine. The SDF project deals with issues in the catchment area of the river Rhine to ensure sustainable development of its floodplains. The issues addressed in this project are trans-national by nature, because sustainable flood management strategies require interregional and trans-national co-operation throughout the river basin. SDF consists of intensive trans-national co-operation involving eight partners in The Netherlands and Germany, which will increase the mutual respect and understanding, by developing measures with trans-national impacts, common issues and in trans-national teams. SDF encompasses 12 pilot projects with an operational focus. SDF partners share knowledge on project management, technical solutions and public participation processes. SDF is co-financed by the European INTERREG IIIb programme which contributes to accelerated implementation of various plans on flood prevention.

Changes of Flood Control Situations and Adjustments of Flood Management Strategies in China

Flooding was recognized as the severest natural hazard in ancient China. Chinese people have accumulated abundant experiences in fighting against flood disasters for millennia. In the past half century, flood control capacity has improved due to the large-scale construction of a flood control engineering system, which plays an important role in ensuring the rapid socio-economic development. However, because of climatic fluctuation and human activities, significant changes to the flood control situation are taking place in China. In the new century, the flood control system has to face a series of challenges, and the flood management strategies must be adjusted accordingly.