Geomorphological numerical modelling of woody dams in CAESAR-Lisflood

2021 ◽  
Author(s):  
Josh Wolstenholme ◽  
Christopher Skinner ◽  
David Milan ◽  
Daniel Parsons
Keyword(s):  
Flood Risk ◽  
Flood Management ◽  
River Channels ◽  
Sensitivity Testing ◽  
Spatial And Temporal Scales ◽  
Natural Processes ◽  
Natural Wood ◽  
Long Term Impact ◽  
Morphology Influence

<p>Natural flood management (NFM) promotes the sustainable enhancement of natural fluvial processes to reduce flooding (SEPA, 2015; Wilkinson et al., 2019), and is increasingly popular for use by community groups, contractors and governments (Kay et al., 2019). Reintroduction of wood to a river channel is a popular form of NFM often achieved through seeding natural logjams, or with an emphasis on engineering through installing woody dams (WDs). WDs are currently installed or being installed in catchments in an effort to reduce flood risk, through hydrograph attenuation, increase biodiversity and improve geomorphic heterogeneity (Wenzel et al., 2014; Burgess-Gamble et al., 2017; Grabowski et al., 2019). A further objective is to emulate the effect of natural wood found in river channels by partially, or completely, blocking the channel to accelerate the recruitment of natural wood as part of the natural wood cycle (Addy & Wilkinson, 2016).</p><p>There is a growing body of evidence supporting the benefits of NFM, however, the hydrogeomorphic effects of WDs are less well understood (Dadson et al., 2017). There is little scientific underpinning concerning the long-term impact of these features upon hydrogeomorphology at reach and catchment-scales. Very few numerically based studies consider the influence of sediment transport on WDs, and how changes in local bed morphology influence their effectiveness. Most NFM research to date has focused upon modelling the effectiveness of local NFM measures in small catchments (<10 km<sup>2</sup>) (Dadson et al., 2017), with less work evident at larger spatial and temporal scales (Kay et al., 2019; Wilkinson et al., 2019).</p><p>There is a need for a verified tool that is able to represent WDs accounting for geomorphic processes and interactions between the dams and morphodynamics, different design specifications of dams, and changing efficacy due to geomorphic evolution. We present the new CAESAR-Lisflood (Coulthard et al., 2013) “Working with Natural Processes” toolkit, capable of representing WDs across a digital experimental environment. Global sensitivity testing was conducted using the Morris method (Morris, 1991) to assess the sensitivity of five aspects of the toolkit, and their potentially influences on geomorphology and flood risk reduction.</p>

scholarly journals Towards risk-based flood management in highly productive paddy rice cultivation – concept development and application to the Mekong Delta

2018 ◽  
Vol 18 (11) ◽  
pp. 2859-2876 ◽  
Author(s):  
Nguyen Van Khanh Triet ◽  
Nguyen Viet Dung ◽  
Bruno Merz ◽  
Heiko Apel
Keyword(s):  
Land Use ◽  
Flood Risk ◽  
Large Scale ◽  
Flood Hazard ◽  
Mekong Delta ◽  
Flood Management ◽  
Paddy Rice ◽  
Rice Cultivation ◽  
Spatially Explicit ◽  
Risk Maps

Abstract. Flooding is an imminent natural hazard threatening most river deltas, e.g. the Mekong Delta. An appropriate flood management is thus required for a sustainable development of the often densely populated regions. Recently, the traditional event-based hazard control shifted towards a risk management approach in many regions, driven by intensive research leading to new legal regulation on flood management. However, a large-scale flood risk assessment does not exist for the Mekong Delta. Particularly, flood risk to paddy rice cultivation, the most important economic activity in the delta, has not been performed yet. Therefore, the present study was developed to provide the very first insight into delta-scale flood damages and risks to rice cultivation. The flood hazard was quantified by probabilistic flood hazard maps of the whole delta using a bivariate extreme value statistics, synthetic flood hydrographs, and a large-scale hydraulic model. The flood risk to paddy rice was then quantified considering cropping calendars, rice phenology, and harvest times based on a time series of enhanced vegetation index (EVI) derived from MODIS satellite data, and a published rice flood damage function. The proposed concept provided flood risk maps to paddy rice for the Mekong Delta in terms of expected annual damage. The presented concept can be used as a blueprint for regions facing similar problems due to its generic approach. Furthermore, the changes in flood risk to paddy rice caused by changes in land use currently under discussion in the Mekong Delta were estimated. Two land-use scenarios either intensifying or reducing rice cropping were considered, and the changes in risk were presented in spatially explicit flood risk maps. The basic risk maps could serve as guidance for the authorities to develop spatially explicit flood management and mitigation plans for the delta. The land-use change risk maps could further be used for adaptive risk management plans and as a basis for a cost–benefit of the discussed land-use change scenarios. Additionally, the damage and risks maps may support the recently initiated agricultural insurance programme in Vietnam.

scholarly journals Integrating Strategic Environmental Assessment to Climate Change Adaption in the Chao Phraya River Basin: Case Study Flood Management Plans in Ayutthaya

2021 ◽  
Vol 6 (2) ◽  
pp. p55
Author(s):  
Wilawan Boonsri Prathaithep ◽  
Vilas Nitivattananon
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Environmental Assessment ◽  
Flood Risk ◽  
Assessment Tool ◽  
Flood Management ◽  
Integrated System ◽  
Strategic Environmental Assessment ◽  
Human Environment ◽  
Impacts Of Climate Change

Traditionally, flood management has concentrated on providing protection against floods using technical measures, but there is currently an international shift towards a more integrated system of flood risk management, whereby flood risk is defined as the probability of flooding multiplied by the potential consequences. Climate change is a great challenge to sustainable development and the Millennium Development Goals (MDGs) in Thailand. The main purpose of this paper is to highlight the challenges associated with the current situation and projected impacts of climate change on the disasters and the human environment in Thailand, to review and explore the potential of Strategic Environmental Assessment (SEA), and to propose SEA in making informed decisions relevant to the implementation of the new adaptation framework in a flood management plan. Thus, current measures on how Thailand is responding to the recent impacts of climate change in river basin planning are presented. It is imperative that an appropriate environmental assessment tool, such as SEA be employed in making rational decisions regarding adaptation frameworks. SEA offers a structured and proactive environmental tool for integrating of climate change adaption into formulating Policies, Plans, and Programs (PPPs) among relevant sectors.

scholarly journals READY: a web-based geographical information system for enhanced flood resilience through raising awareness in citizens

2015 ◽  
Vol 3 (2) ◽  
pp. 993-1024
Author(s):  
R. Albano ◽  
A. Sole ◽  
J. Adamowski
Keyword(s):  
Information System ◽  
Geographical Information System ◽  
Flood Risk ◽  
General Public ◽  
Flood Management ◽  
Geographical Information ◽  
Web Based ◽  
Flood Risks ◽  
Hazard And Risk ◽  
Self Protection

Abstract. As evidenced by the EU Floods Directive (2007/60/EC), flood management strategies in Europe have undergone a shift in focus in recent years. The goal of flood prevention using structural measures has been replaced by an emphasis on the management of flood risks using non-structural measures. One implication of this is that it is no longer public authorities alone who take responsibility for flood management. A broader range of stakeholders, who may experience the negative effects of flooding, also take on responsibility to protect themselves. Therefore, it is vital that information concerning flood risks are conveyed to those who may be affected in order to facilitate the self-protection of citizens. Experience shows that even where efforts have been made to communicate flood risks, problems persist. There is a need for the development of new tools, which are able to rapidly disseminate flood risk information to the general public. To be useful, these tools must be able to present information relevant to the location of the user. Moreover, the content and design of the tool need to be adjusted to laypeople's needs. Dissemination and communication influences both people's access to and understanding of natural risk information. Such a tool could be a useful aid to effective management of flood risks. To address this gap, a Web-based Geographical Information System, (WebGIS), has been developed through the collaborative efforts of a group of scientists, hazard and risk analysts and managers, GIS analysts, system developers and communication designers. This tool, called "READY: Risk, Extreme Events, Adaptation, Defend Yourself", aims to enhance the general public knowledge of flood risk, making them more capable of responding appropriately during a flood event. The READY WebGIS has allowed for the visualization and easy querying of a complex hazard and risk database thanks to a high degree of interactivity and its easily readable maps. In this way, READY has enabled fast exploration of alternative flood scenarios or past calamitous events. Combined also with a system of graphic symbols designed ad hoc for communication of self-protection behaviors, it is believed READY could lead to an increase in citizen participation, informed discussion and consensus building. The platform has been developed for a site-specific application, i.e. the Basilicata Region, Italy, has been selected as pilot application area. The goal of the prototype is to raise citizen awareness of flood risks, and to build social capacity and enhanced resilience to flood events.

scholarly journals Evaluation of Flood Management Policies in the City of Yagoua (Far-North Region, Cameroon)

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Baugard Ovono Nogo Edongo ◽  
Pr. Najem Dhaher ◽  
Pr. Natali Kossoumna Liba’a
Keyword(s):  
Flood Management ◽  
Far North ◽  
Management Policies ◽  
The City

Integrated Flood Risk Analysis for Assessing Flood Protection Strategies

2010 ◽  
pp. 244-263
Author(s):  
J. Ernst ◽  
B.J. Dewals ◽  
S. Detrembleur ◽  
P. Archambeau ◽  
S. Erpicum ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Flood Risk ◽  
Management Strategies ◽  
Cost Effective ◽  
Flood Management ◽  
Flood Protection ◽  
River Meuse ◽  
Flood Risk Analysis ◽  
Protection Strategies ◽  
The Cost

The present chapter describes an end-to-end methodology for assessing flood protection strategies, including the whole methodological process from hydrological statistics to detailed 2D hydraulic modelling, damage calculation and flood risk evaluation. This risk-based approach serves as a component of a decision-support system (DSS) developed in Belgium for identifying cost-effective flood management strategies in the context of climate change. The DSS accounts for both hydraulic and socio-economic parameters to quantify the benefits (in terms of avoided risk) and the cost of each strategy. Besides reviewing fundamentals of flood risk assessment, including the inundation model and main concepts related to flood risk, a consistent methodology for micro-scale flood risk analysis is presented in detail, combining complementary sources of GIS information such as high resolution and high accuracy land use database as well as socio-economic datasets. Finally a case study on a main tributary of river Meuse in Belgium is described.

scholarly journals How are flood risk estimates affected by the choice of return-periods?

2011 ◽  
Vol 11 (12) ◽  
pp. 3181-3195 ◽  
Author(s):  
P. J. Ward ◽  
H. de Moel ◽  
J. C. J. H. Aerts
Keyword(s):  
Flood Risk ◽  
Damage Model ◽  
Area Under The Curve ◽  
Flood Management ◽  
Exceedance Probability ◽  
Return Periods ◽  
Inundation Maps ◽  
Risk Estimates ◽  
Risk Curve ◽  
Inundation Extent

Abstract. Flood management is more and more adopting a risk based approach, whereby flood risk is the product of the probability and consequences of flooding. One of the most common approaches in flood risk assessment is to estimate the damage that would occur for floods of several exceedance probabilities (or return periods), to plot these on an exceedance probability-loss curve (risk curve) and to estimate risk as the area under the curve. However, there is little insight into how the selection of the return-periods (which ones and how many) used to calculate risk actually affects the final risk calculation. To gain such insights, we developed and validated an inundation model capable of rapidly simulating inundation extent and depth, and dynamically coupled this to an existing damage model. The method was applied to a section of the River Meuse in the southeast of the Netherlands. Firstly, we estimated risk based on a risk curve using yearly return periods from 2 to 10 000 yr (€ 34 million p.a.). We found that the overall risk is greatly affected by the number of return periods used to construct the risk curve, with over-estimations of annual risk between 33% and 100% when only three return periods are used. In addition, binary assumptions on dike failure can have a large effect (a factor two difference) on risk estimates. Also, the minimum and maximum return period considered in the curve affects the risk estimate considerably. The results suggest that more research is needed to develop relatively simple inundation models that can be used to produce large numbers of inundation maps, complementary to more complex 2-D–3-D hydrodynamic models. It also suggests that research into flood risk could benefit by paying more attention to the damage caused by relatively high probability floods.

scholarly journals Towards Integrated Flood Risk and Resilience Management

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1789 ◽  
Author(s):  
Guangtao Fu ◽  
Fanlin Meng ◽  
Mónica Rivas Casado ◽  
Roy S. Kalawsky
Keyword(s):  
Flood Risk ◽  
Management Strategies ◽  
Flood Management ◽  
Future Research ◽  
Risk And Resilience ◽  
Research Directions ◽  
Adverse Impacts ◽  
Hazard And Risk ◽  
Future Research Directions ◽  
Resilience Management

Flood resilience is an emerging concept for tackling extreme weathers and minimizing the associated adverse impacts. There is a significant knowledge gap in the study of resilience concepts, assessment frameworks and measures, and management strategies. This editorial introduces the latest advances in flood risk and resilience management, which are published in 11 papers in the Special Issue. A synthesis of these papers is provided in the following themes: hazard and risk analysis, flood behaviour analysis, assessment frameworks and metrics, and intervention strategies. The contributions are discussed in the broader context of the field of flood risk and resilience management and future research directions are identified for sustainable flood management.

scholarly journals Flood Risk and Resilience in the Netherlands: In Search of an Adaptive Governance Approach

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2563
Author(s):  
Astrid Molenveld ◽  
Arwin van Buuren
Keyword(s):  
The Netherlands ◽  
Flood Risk ◽  
Flood Management ◽  
Adaptive Governance ◽  
Risk And Resilience ◽  
Policy Regime ◽  
Adaptive Policy ◽  
The Face ◽  
The Government ◽  
Institutional Analysis And Development

In the Netherlands, dealing with the risk of flooding in the face of the current climate change requires a governance approach that is less based upon the long-standing tradition of prevention and protection, and more oriented toward ideas of resilience and adaptivity. Such an approach is assumed to be more resilient compared to static approaches and better equipped to deal with the indeterminate character of a problem like flood risk. This article presents the Dutch attempt to introduce a more polycentric and adaptive governance approach in flood management, called multilayered safety (MLS). We studied this approach via interviews and an extensive document study, and analyzed the institutions governing the issue using the Institutional Analysis and Development (IAD) framework of Elinor Ostrom. For years, the issue was in the hands of a small network of actors, mainly occupied by water experts and governed by a strong lead organization and permanent bodies. While introducing a new, more adaptive policy concept the government encountered both resistance and inability within the existing policy regime. This article shows that the issue of flood safety was successfully ‘tamed’ for decades. Adopting a more adaptive and polycentric approach necessitates ‘untaming’ the issue of flood safety.

Nature-Based Solutions: Dependency of Effectiveness on Spatial Configuration

2020 ◽  
Author(s):  
Ian Pattison
Keyword(s):  
Flood Risk ◽  
Critical Infrastructure ◽  
Spatial Configuration ◽  
Storm Track ◽  
Spatial Location ◽  
Flood Management ◽  
Clear Understanding ◽  
Storm Events ◽  
Catchment Scale ◽  
The Impact

<p>Several recent large flood events have had severe economic and social impacts. The winter 2015-16 UK floods resulted in 16,000 properties flooding and damage to critical infrastructure. It is increasingly being recognised that traditional approaches of flood defence are not sustainable due to the pressures of climate change and economic constraints. The solution to the flood risk problem in cities is no longer seen as being just on-site, and thinking is shifting upstream and to the catchment/landscape scales, known as Nature-Based Solutions or Natural Flood Management (NFM). The approach consists of measures that “Work with Natural Processes”, such as storing water in ponds, and slowing the flow in rivers. The evidence for the impacts is strong at the local scale, but the larger spatial scale impact is highly uncertain due to the cumulative impacts resulting from amplifying/mitigating effects of different interventions, controlled by spatial location and storm-track interaction.</p><p>To date, Nature-Based Solution schemes have proceeded on an opportunistic basis, without a clear design strategy (which measure and where to implement it). However, if schemes are implemented without clear understanding of their impacts, they may, at best, fail to achieve the optimum flood reduction benefit downstream, or, at worst, make flooding more severe (if implemented in inappropriate locations, when tributaries’ flows are synchronised).  </p><p><span>Impacts of NFM measures are spatially and temporally dependent i.e. the same intervention in two locations will have different effects on flows, and the same intervention will have different impacts during different storm events. Therefore, it is essential that when strategically designing NFM schemes for catchments, that WHERE? and WHAT? are answered together to optimise the impact, as it is possible that whilst upstream NFM may be beneficial locally it may make tributary peaks coincide and make flood magnitudes worse downstream. Here we demonstrate the importance of the spatial configuration of Nature-Based Solutions on their catchment scale effectiveness in reducing flood risk.</span></p>

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