Staged cost optimization of urban storm drainage systems based on hydraulic performance in a changing environment

International audienceUrban flooding causes large economic losses, property damage and loss of lives. The impact of environmental changes mainly, the urbanization and the climatic change leads to increased runoff and increased peak flows which the drainage system must be able to cope with to overcome possible damage and inconveniences caused by the induced flooding. Allowing for detention storage to compliment the capacity of the drainage system network is one of the approaches to reduce urban floods. The traditional practice was to design systems against stationary environmental forcings ? including design rainfall, landuse, etc. Due to the rapid change in climate-environment, this approach is no longer economically viable and safe, and explicit consideration of changes that gradually take place during the life-time of the drainage system is warranted. In this paper, a staged cost optimization tool based on the hydraulic performance of the drainage system is presented. A one dimensional hydraulic model is used for hydraulic evaluation of the network together with a genetic algorithm based optimization tool to determine optimal intervention timings and amounts throughout the lifespan of the drainage network. The model was applied in a case study area in the city of Porto Alegre, Brazil. It was concluded that considerable financial savings and/or additional level of flood-safety can be achieved by approaching the design problem as a staged plan rather than one-off scheme

Adaptation tipping points of awetland under a drying climate

Wetlands experience considerable alteration to their hydrology, which typically contributes to a decline in their overall ecological integrity. Wetland management strategies aim to repair wetland hydrology and attenuate wetland loss that is associated with climate change. However, decision makers often lack the data needed to support complex social environmental systems models, making it difficult to assess the effectiveness of current or past practices. Adaptation Tipping Points (ATPs) is a policy-oriented method that can be useful in these situations. Here, a modified ATP framework is presented to assess the suitability of ecosystem management when rigorous ecological data are lacking. We define the effectiveness of the wetland management strategy by its ability to maintain sustainable minimum water levels that are required to support ecological processes. These minimum water requirements are defined in water management and environmental policy of the wetland. Here, we trial the method on Forrestdale Lake, a wetland in a region experiencing a markedly drying climate. ATPs were defined by linking key ecological objectives identified by policy documents to threshold values for water depth. We then used long-term hydrologic data (1978–2012) to assess if and when thresholds were breached. We found that from the mid-1990s, declining wetland water depth breached ATPs for the majority of the wetland objectives. We conclude that the wetland management strategy has been ineffective from the mid-1990s, when the region’s climate dried markedly. The extent of legislation, policies, and management authorities across different scales and levels of governance need to be understood to adapt ecosystem management strategies. Empirical verification of the ATP assessment is required to validate the suitability of the method. However, in general we consider ATPs to be a useful desktop method to assess the suitability of management when rigorous ecological data are lacking

New policies to deal with climate change and other drivers impacting on resilience to flooding in urban areas: The CORFU approach

Copyright © 2011 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Environmental Science and Policy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Environmental Science and Policy, Vol. 14 Issue 7 (2011). DOI: 10.1016/j.envsci.2011.05.008In the context of urban flood management, resilience is equal to resisting, recovering, reflecting and responding. The variety of causes of flooding and their consequences underpin the need for increased and internationally coordinated efforts to enhance technologies and policies for dealing with floods. This paper addresses this issue and presents some novel research ideas related to resilience to flooding in urban areas, which are under development within the EU FP7 project ‘Collaborative research on flood resilience in urban areas’ (CORFU). The approach adopted in this project aims to quantify the cost-effectiveness of resilience measures and integrative and adaptable flood management plans for different scenarios of relevant drivers: urban development, socio-economic trends and climate changes. It is believed that the way in which the different models are being put together, combined with the variability of conditions in case study areas in Asia and in Europe, will ultimately enable more scientifically sound policies for the management of the consequences of urban flooding

Introducing Adaptive Flood Risk Management in England, New Zealand, and the Netherlands: The Impact of Administrative Traditions

Climate change adaptation creates significant challenges for decision makers in the flood risk-management policy domain. Given the complex characteristics of climate change, adaptive approaches(which can be adjusted as circumstances evolve) are deemed necessary to deal with a range of uncertainties around flood hazard and its impacts and associated risks. The question whether implementing adaptive approaches is successful highly depends upon how the administrative tradition of a country enable or hinder applying a more adaptive approach. In this article, we discern how the administrative tradition in the Netherlands, England, and New Zealand impact upon the introduction of adaptive flood risk management approaches. Using the concept of administrative traditions, we aim to explain the similarities and/or differences in how adaptive strategies are shaped and implemented in the three different state flood management regimes and furthermore, which aspects related to administrative traditions are enablers or barriers to innovation in these processe

Informing UK governance of resilience to climate risks: improving the local evidence-base

International assessments of evidence on climate change (e.g. Intergovernmental Panel on Climate Change, IPCC) or national climate change risk assessments (e.g. UK Climate Change Risk Assessment, CCRA) do not offer a sufficiently granular perspective on climate impacts to adequately inform governance of resilience to climate risks at the local level. Using an analysis of UK decision-makers managing and responding to heatwaves and flood risks, this paper argues how more robust local evidence is needed to inform decision-making regarding adaptation options for enhancing local resilience. We identify evidence gaps and issues relating to local climate change impacts, including sources and quality of evidence used, adequacy and accessibility of evidence available, ill-communicated evidence and conflicting or misused evidence. A lack of appreciation regarding how scientific evidence and personal judgement can mutually enhance the quality of decision-making underpins all of these gaps. Additionally, we find that the majority of evidence currently used is reductively based upon socio-economic and physical characteristics of climate risks. We argue that a step change is needed in local climate resilience that moves beyond current physical and socio-economic risk characterisation to a more inclusive co-constitution of social and politically defined climate risks at the local scale that are better aligned with the local impacts felt and needs of stakeholders

The resilience approach to climate adaptation applied for flood risk; Dissertation, UNESCO-IHE Institute for Water Education, Delft.

The uncertainties associated with making investment decisions for flood risk management can be significant and arise from, amongst other factors, a lack of knowledge about external drivers, like climate change. These uncertainties make it necessary to succeed the (quasi-)stationarity approach for the development of investment strategies. Otherwise, such strategies can be maladaptive, resulting in e.g. unnecessary costs of potentially irreversible measures. This dissertation presents a potential way forward for adaptation to climate change, termed the resilience approach. The resilience approach takes a dynamic perspective on adaptive processes and the effects of these processes at/across different spatio-temporal scales. The methods required for applying the resilience approach should give insight into and promote the ability of a system to deal with future change. This comprises the ability not only to respond to change as a threat, but also to take advantage of opportunities that arise from future change. Case study experience is provided with four methods: Adaptive Policy Making, Real-In-Options, Adaptation Tipping Points and - Adaptation Mainstreaming Opportunities. This dissertation discusses the concept, procedure and benefits/limitations of each method, examining its usefulness for informing investment decisions for flood risk management. It gives specific recommendations on which method to use under what circumstances

Maturity Improvements in Flood Protection Asset Management across the North Sea Region

North Sea Region countries depend heavily on flood protection infrastructure, such as dikes, dams, sluices and flood gates. Knowledge on where, when and how much to invest to ensure functioning is of crucial importance for asset owners and operators. This requires asset management approaches that are adaptable, respond to feedback and function within various contexts. The FAIR (Flood defense infrastructure Asset management & Investment in Renovation, adaptation, optimisation and maintenance) project has developed a unique framework to ensure that asset management processes are adaptive, comprehensive and make effective connections across strategic, tactical and operational contexts. The framework has for the first time informed an assessment of maturity of five flood protection asset management organisations in the North Sea Region, using a seven-factor maturity assessment model. This paper describes the self-assessment process and the self-reported maturity changes during the project. Maturity assessments were undertaken on two occasions, at the start of the project, and again toward the end. This has revealed how the baseline level of maturity for each organisation developed over the course of the three-year project. The observed maturity changes indicate that adopting the FAIR framework has added value in improving current approaches to asset management

Implementatie meerlaagsveiligheid in Nederland: realisatie plannen vergt institutionele verandering

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