Flood Vulnerability to Climate Change through Hydrological Modeling

Abstract

Determination of flood vulnerability to climate change is one of the most critical issues for regional water management. Most of the previous studies related to system vulnerabilities to climate change were either a qualitative assessment without the support of hydrological modeling or too complex to apply them to real-world systems. In this study, a modeling and assessment system is proposed to tackle flood vulnerability to the climate change through the incorporation of future climate change scenarios, rainfall-runoff simulation, and vulnerability estimation within an integrated frame. The developed approach is applied to provide decision support for flood management of the Swift Current Creek watershed in Western Canada. The approach not only is useful to determine relative flood vulnerabilities to climate change for supporting flood control planning in the watershed, but also can be extended to estimate vulnerabilities of water quality and water supply to climate change.     

Prediction of climate change effects of fish communities in the Mackinaw River watershed, Illinois, USA.

As part of an integrated assessment of multiple sector impacts produced by predicted changes in climate we have integrated a set of models, which provide predictions of fish populations under changing flow and temperature regimes. The core of the approach is the U. S. Fish and Wildlife Service Physical Habitat Simulation Model (PHABSIM). PHABSIM estimates habitat conditions based on flow, which are life stage specific. The output from PHABSIM is used to model fish populations, considering both flow and a temperature threshold, which affects spawning date. Water temperatures were modelled based on air temperature. The resulting assessment tool provides the means to evaluate the effect of multiple stressors produced by climate change scenarios. The model has been used to estimate smallmouth bass (Micropterus dolomieui) populations for representative reaches of the Mackinaw River, Illinois. The model has been used to illuminate population effects of changing flow and temperature under historical climate/weather conditions, as well as under climate change scenarios. The integrated models in the assessment tool have provided a useful addition to watershed management, improving our capacity to evaluate natural resources impact at temporal scales typical of climate change, and management response systems.     

Spatial Assessment of Climate Risk for Investigating Climate Adaptation Strategies by Evaluating Spatial-Temporal Variability of Extreme Precipitation

In response to the impacts of extreme precipitation on human or natural systems under climate change, the development of climate risk assessment approach is a crucial task. In this paper, a novel risk assessing approach based on a climate risk assessment framework with copula-based approaches is proposed. Firstly, extreme precipitation indices (EPIs) and their marginal distributions are estimated for historical and future periods. Next, the joint probability distributions of extreme precipitation are constructed by copula methods and tested by goodness-of-fit indices. The future joint probabilities and joint return periods (JRPs) of the EPIs are then evaluated. Finally, change rates of JRPs for future periods are estimated to assess climate risk with the quantitative data of exposure and vulnerability of a protected target. An actual application in Taiwan Island is successfully conducted for climate risk assessment with the impacts of extreme precipitation. The results indicate that most of regions in Taiwan Island might have higher potential climate risk under different scenarios in the future. The future joint probabilities of precipitation extremes might cause the high risk of landslide and flood disasters in the mountainous area, and of inundation in the plain area. In sum, the proposed climate risk assessing approach is expected to be useful for assisting decision makers to draft adaptation strategies and face high risk of the possible occurrence of natural disasters.

     

Workshop 3 (synthesis): climate variability, water systems and management options.

Addressing climate variability now will better prepare us for future impacts of climate change. Sustained, multi-stakeholder dialogue at local through national levels is an approach that will reach the widest audience, helped by tools that illustrate vulnerability such as the Climate Vulnerability Index. Integrated water resources management deals with managing for variability and change and is therefore highly appropriate for dealing with climate impacts.     

Robustness,Uncertainty and Sensitivity Analyses of the TOPSIS Method for Quantitative Climate Change Vulnerability: a Case Study of Flood Damage

Multi-criteria decision making (MCDM) techniques have been used to evaluate and rank the spatial flood vulnerability to climate change. However, various sources of uncertainty, such as the determination of evaluation criteria, the assignment of criteria weights and performance values, exist in the application of MCDM methods. In this study, three existing methods were combined to quantify the risk and uncertainties inherent to the process of climate change vulnerability assessment, which is called the TOPSIS-based Robustness-Uncertainty-Sensitivity (RUS) approach. The A1B scenario was used to assess the vulnerability of seven metropolitan cities in South Korea to climate change. Twenty indicators that are closely related to the cause of and deterioration from the flood risk and the resulting damages were selected by two surveys of experts, and the weights of these factors were determined by using the Delphi technique, which can derive the subjective weights. Based on the derived weights, the vulnerability ranking was calculated using the TOPSIS method, one of the most popular MCDM methods. This TOPSIS-based RUS approach was used to analyze the robustness of the vulnerability rankings for the assessed cities, to derive the minimum changed weights of the single and multiple criteria that determine the rank equivalence (or reversal) between any two cities and to check the sensitivities of the performance values to the vulnerability rankings. This study showed the effectiveness of the RUS approach for assessing the vulnerability to climate change, demonstrating the application of flood vulnerability.     

Development of a method for assessing flood vulnerability.

Over the past few decades, a growing number of studies have been conducted on the mechanisms responsible for climate change and the elaboration of future climate scenarios. More recently, studies have emerged examining the potential effects of climate change on human societies, including how variations in hydrological regimes impact water resources management. According to the Intergovernmental Panel on Climate Change's third assessment report, climate change will lead to an intensification of the hydrological cycle, resulting in greater variability in precipitation patterns and an increase in the intensity and frequency of severe storms and other extreme events. In other words, climate change will likely increase the risks of flooding in many areas. Structural and non-structural countermeasures are available to reduce flood vulnerability, but implementing new measures can be a lengthy process requiring political and financial support. In order to help guide such policy decisions, a method for assessing flood vulnerability due to climate change is proposed. In this preliminary study, multivariate analysis has been used to develop a Flood Vulnerability Index (FVI), which allows for a comparative analysis of flood vulnerability between different basins. Once fully developed, the FVI will also allow users to identify the main factors responsible for a basin's vulnerability, making it a valuable tool to assist in priority setting within decision-making processes.     

Using Large Climate Ensembles to Plan for the Hydrological Impact of Climate Change in the Freshwater Environment

We explore the use of large ensembles of climate scenarios to inform climate change adaptation in response to hydrological impacts on the freshwater environment, using a sensitive chalk river in south east England to illustrate the approach. The climateprediction.net experiment provides large ensembles of transient climate series from 1920 to 2080. We use 246 transient climate series in the CATCHMOD rainfall-run-off model to develop large ensembles of plausible river flows for the River Itchen. This transient ensemble allows the exploration of how flows may change through the twenty-first century, and demonstrates the range of possible consequences for freshwater ecosystems, based on invertebrate community impacts. Hydrological modelling of flow sequences including abstraction allows the continued effectiveness of river support from groundwater to be assessed. A new environmental impact matrix considers the response of the freshwater ecosystem in the Itchen, concentrating particularly on macro-invertebrates. Through the century increasing numbers of models fail the flow targets, with a minority of models suggesting flows that would lead to irreversible change to the invertebrate community. The large ensemble provides a richer picture of the range of possible change, allowing managers to explore a range of different responses. The approach used is illustrative, but demonstrates that large ensembles may be of great value in improving the understanding of the possible impact of climate change, provided that they can be communicated effectively to decision-makers.     

Sensitivity of the Red River Basin Flood Protection System to Climate Variability and Change

An original modeling framework for assessment of climate variation and change impacts on the performance of complex flood protection system has been implemented in the evaluation of the impact of climate variability and change on the reliability, vulnerability and resiliency of the Red River Basin flood protection system (Manitoba, Canada). The modeling framework allows for an evaluation of different climate change scenarios generated by the global climate models. Temperature and precipitation are used as the main factors affecting flood flow generation. System dynamics modeling approach proved to be of great value in the development of system performance assessment model. The most important impact of climate variability and change on hydrologic processes is reflected in the change of flood patterns: flood starting time, peak value and timing. The results show increase in the annual precipitation and the annual streamflow volume in the Red River basin under the future climate change scenarios. Most of the floods generated using three different climate models had an earlier starting time and peak time. The assessment of the performance of Red River flood protection system is based on the flood flows, the capacity of flood control structures and failure flow levels at different locations in the basin. In the Assiniboine River Basin, higher reliabilities at downstream locations are obtained indicating that Shellmouth reservoir plays an important role in reducing downstream flooding. However, a different trend was identified in the Red River Basin. The study results show that flood protection capacity of the Red River infrastructure is sufficient under low reliability criteria but may not be sufficient under high reliability criteria.     

Climatic Change Impact on Water Resources in a Systems Perspective

Global climate change related to natural and anthropogenic processes has been the topic of concern and interest world wide. Despite ongoing research efforts, the climate predictions cannot be rated any better than speculative or possible scenarios whose probability of occurrence is, at the present stage, impossible to assess. One of the most significant impacts of the greenhouse effect is anticipated to be on water resources, including different elements of the hydrologic cycle, water supply and demand, regional vulnerability, and water quality. Thus, the impact of climate change appears to be an additional component on top of the large number of existing water-related problems.The existence of the greenhouse effect, the increase of greenhouse gas emissions, and the rise of corresponding concentrations are things that are certain. However, their impacts on hydrology and water management are highly uncertain. In the latter area, one needs information on much smaller spatial and temporal scales than those used in climate studies. The objective of the present paper is to analyze the climate change impact on water resources in a system's perspective, to discuss scientific gaps, and challenge scientific issues. The role of different scales and uncertainties, as well as the hydrological view of global circulation models are also discussed. Our preparedness for probable global (climate) change is reviewed in terms of assessment, planning, design and adaptation.     

农业生态系统对气候变化的脆弱性评价——以河北省农业综合开发项目区为例

选取河北省农业综合开发项目区农业生态系统作为研究对象,将其划分为2个一级区8个亚区。通过采用实地调查与专家推荐的方法,确定了河北省农业对气候变化的脆弱性评价体系;采用专家打分和层次分析法完成了现状条件下农业对气候变化的脆弱性评价。评价结果表明坝上高原和冀西北山间盆地亚区农业对气候变化非常脆弱,山麓平原亚区农业对气候变化较为适中,滨海平原亚区农业对气候变化脆弱性逐渐变缓。评价结果基本上反映出河北省农业开发项目区生态系统气候脆弱性现状的一个大致轮廓,可供进一步研究借鉴和参考。     

A comprehensive approach and methods for glacial lake outburst flood risk assessment,with examples from Nepal and the transboundary area

Like other mountainous areas, Nepal is highly vulnerable to glacial lake outburst floods (GLOFs), and this vulnerability has increased due to climate change. Risk reduction strategies must be based on a comprehensive risk assessment. A comprehensive methodological approach for GLOF risk assessment is described and illustrated in case studies of the potential GLOF risk posed in Nepal by four glacial lakes, one located in China. People, property and public infrastructure (including hydropower plants, roads and bridges) are vulnerable, and there is a need to integrate GLOF risk reduction strategies into national policies and programmes.     

Analysis of Impacts of Climate Change and Human Activities on Hydrological Drought: a Case Study in the Wei River Basin,China

Climate change and human activity are the two major drivers that can alter hydrological cycle processes and influence the characteristics of hydrological drought in river basins. The present study selects the Wei River Basin (WRB) as a case study region in which to assess the impacts of climate change and human activity on hydrological drought based on the Standardized Runoff Index (SRI) on different time scales. The Generalized Additive Models in Location, Scale and Shape (GAMLSS) are used to construct a time-dependent SRI (SRI_var) considering the non-stationarity of runoff series under changing environmental conditions. The results indicate that the SRI_var is more robust and reliable than the traditional SRI. We also determine that different driving factors can influence the hydrological drought evolution on different time scales. On shorter time scales, the effects of human activity on hydrological drought are stronger than those of climate change; on longer time scales, climate change is considered to be the dominant factor. The results presented in this study are beneficial for providing a reference for hydrological drought analysis by considering non-stationarity as well as investigating how hydrological drought responds to climate change and human activity on various time scales, thereby providing scientific information for drought forecasting and water resources management over different time scales under non-stationary conditions.     

Climate Change and Water Resource Availability: An Impact Assessment for Bombay and Madras,India

ABSTRACT

Global climate change associated with rising atmospheric concentrations of greenhouse gases may alter regional temperature and precipitation patterns. Such changes could threaten the availability of water resources/Or rapidly growing Third World cities, many of which are already experiencing severe water supply deficiencies. This paper investigates the potential impacts of climate change on water resource availability for two Indian cities, Bombay and Madras. The paper begins by discussing future trends for population growth and water demand in each city. Nat, using climate change scenarios based on three general circulation models (GCMs), the paper assesses how climate change may affect water availability in the two urban regions. The assessment is conducted through the use of a monthly dryness index measuring potential evapotranspiration and precipitation. For each region, the dryness index under “normal” climatic conditions is compared with indexes created using GCM scenarios. The results of this assessment indicate that, unless large increases in regional precipitation accompany climate warming, higher rates of evapotranspiration will mean reduced water availability for both cities. The paper concludes by discussing some implications for water management in Third World cities.     

水文改变指标体系在生态水文研究中的应用综述

回顾了水文改变指标体系的发展历程,详细介绍了水文改变指标体系所包含的水文改变指标、变化范围法和环境流量成分3部分内容,总结了水文改变指标体系在水文情势改变评估、生态环境影响评估、生态环境流量估算等方面的应用;指出水文改变指标体系是一种简便有效的评估工具,在水文情势变化及其生态效应评估和水资源管理实践上具有广泛的应用前景,但水文改变指标体系也存在参数冗余问题,未来发展可以耦合生态水文模型。     

Climate change and food-water supply from Africa's drylands: local impacts and teleconnections through global commodity flows

This article uses the WaterWorld Policy Support System, coupled with a global database for commodity flows, to examine the impacts of AR4 SRES climate change scenarios on Africa's drylands and the commodity flows that originate from them. It shows that changes to precipitation and, to a lesser extent, temperature in Africa's drylands can significantly affect the potential to supply water-for-food locally and internationally. By comparing the geographical distribution of climate change with the supply chain–connected distribution of climate change, it shows how food-water impacts of climate change may affect local dryland populations but also those dependent on these flows from afar.     

Climate Change Adaptation Indicators to Assess Wastewater Management and Reuse Options in the Mekong Delta, Vietnam

Climate change adaptation indicators have played a critical role in the increased understanding of potential climate change impacts. In this research, 6 climate change adaptation indicators were identified for Can Tho City in the Mekong Delta of Vietnam: (1) Rice production from wastewater during winter-spring crop; (2) % of irrigation water demand satisfied by treated wastewater; (3) % of nutrient demand satisfied by treated wastewater; (4) % remaining flow downstream of Can Tho in the Hau River; (5) environmental benefits; and (6) total investment cost for wastewater treatment. These indices were selected to assess various options/strategies for wastewater management and reuse in Can Tho City as a means to improve the City’s resilience to climate change. From an environmental perspective, this study shows the benefits for Can Tho City to set up a strategy to treat and reuse wastewater from catfish farming as the priority among four assessed scenarios with different climate change impact factors. It is concluded that adaptation can be assessed by the indicators because they can define whether adaptation policies and measures are implemented and whether vulnerability is reduced through effective actions.     

Evaluation of Vulnerability to Extreme Climatic Events in the Brazilian Amazonia: Methodological Proposal to the Rio Acre Basin

The southern border of the Brazilian Amazon is one of the most sensitive areas to deforestation in Brazil. In addition to problems related to changes in land use, new issues are emerging, including climate change and its negative effects on the regional hydrological cycle. In recent years considerable research has been undertaken focusing on climate change and its effects on Amazon Biodiversity, carbon cycle, fire incidence and even on regional water resources, but there is very little research linking territorial planning and public policies to prospective planning scenarios and climate change and the necessary adaptation or mitigation actions to address climate vulnerability. This study examines issues pertaining to social, economic and environmental vulnerability, including new challenges posed by climate change. Examples of environmental problems related to climate dynamics of the Rio Acre Basin are floods and dry periods such as the major drought of 2005 and the 2009 flood. The use of methodology for integrated assessment of vulnerability to river basins in Amazon Region constitutes a valuable instrument for territorial planning, since it takes into account both the challenges of poverty and the environmental fragility, as well the possible aggravations of extreme climatic events in the future.     

Development of Adaptation Measures for Water Resources

Many countries are preparing national climate change action plans that describe specific m easures they are taking to mitigate greenhouse gas emissions and adapt to the potential effects of climate change. Am ong the reasons for preparing such plans is that climate change is likely to occur and many anticipatory measures that would be taken in response to climate change are no-regret measures that will produce benefits even if climate does not change. Additionally, these plans can serve as communications required by the Framework Convention on Climate Change. This article proposes an assessment process for anticipatory adaptation m easures that will enable countries to identify, select and implement measures to adapt to climate change. These measures anticipate potential climate changes and thus must be flexible enough to m eet objectives under a wide variety of future clim ate conditions. The process builds on assessments of vulnerability by focusing on adaptation m easures for the most sensitive regions, or populations within a country. Potential anticipatory adaptation measures are identified and two or three are chosen based on expert judgement regarding which measures would produce the greatest benefits and be easiest to implement. Formal analytic techniques are used to assess the benefits and costs of each of the m easu res and to evaluate barriers to implementation. The measure that has the greatest net benefits and is easiest to implement is selected. The final step in the process is preparing an implementation plan. The application of the process is illustrated by examining a hypothetical reservoir threatened by climate change.