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.     

我国沿海城市洪潮组合风险分析

针对沿海城市防洪安全和经济可持续发展的问题,从气候变化和人类活动两个方面对沿海城市洪涝事件的成因进行了归纳。以深圳市为例,选取大沙河上游西沥水库站和深圳湾赤湾潮位站为代表站,基于Copula函数,对深圳市洪潮组合进行风险分析。结果表明,虽然降水和高潮位的双阈值组合风险率小于单域值组合风险率,但深圳市同时遭遇暴雨和高潮位时所造成的城市洪涝灾害更为严重,经济损失和人员伤亡更为巨大;在城市防洪防潮排涝规划、设计时需更加关注降水和潮位的双阈值组合风险率大小。     

Outdoor Water Use as an Adaptation Problem: Insights from North American Cities

Recent efforts to influence the efficiency and timing of urban indoor water use through education, technology, conservation, reuse, economic incentives, and regulatory mechanisms have enabled many North American cities to accommodate population growth and buffer impacts of drought. It is unlikely that this approach will be equally successful into the future because the source of conservation will shift from indoor to outdoor use. Outdoor water is climate sensitive, difficult to measure, hard to predict, linked to other components of complex and dynamic urban resource systems, imbued with behavioral and cultural dimensions, and implicated in societal conflicts about climate risk, modern lifestyles, social justice, and future growth. Outdoor water conservation is not a traditional management problem focused on the water sector, assuming a stationary climate, and set aside from public debate. Instead, outdoor water is an adaptation problem, involving complex and uncertain system dynamics, the need for cross-sector coordination, strategies for dealing with climatic uncertainty, and mechanisms for engaging stakeholders with differing goals. This paper makes the case for treating outdoor water as an adaptation problem and offers a six-point strategy for how cities can better prepare their water systems for the uncertainties of climate and societal change.     

Some rationales for risk sharing and financing adaptation.

Current climate variability and anticipated climate change challenge our water systems and our financial resources. The sharing of economic losses due to weather related hazards and the sharing of costs that result from protecting lives and property take place in different forms, but are currently insufficient. In this paper we discuss three different rationales for financing disaster losses through public and private arrangements, as well as options for financing adaptation, with a special focus on water management. We propose that financial arrangements for risk sharing and climate change adaptation should be reconsidered, in a more structured approach, to be able to deal with both disaster losses and the costs that arise because of climate change adaptation, e.g. for water management, in both developing and developed countries.     

Water Use and Climate Stressors in a Multiuser River Basin Setting: Who Benefits from Adaptation?

Adapting to new climate conditions will require an intricate mix of knowledge, planning, coordination, and foresight. There is increasing sectoral evidence on the implementation of successful adaptation actions. However, the success of these actions when we consider the interdependencies among sectors remains debatable. This paper aims to assess who benefits from implementing adaptation options in a multiuser river basin to both climate-induced and demographic stress on water use. Our analysis relies on a hydro-economic model that considers two sets of water users: agriculture and urban households. We innovate in our modelling approach by analyzing and explicitly integrating the household-level economic behavior through its water demand. We assess the cross-user consequences of autonomous and planned adaptation actions. We provide insights into the different trade-offs at the basin level, demonstrating the compatibilities and divergences between agriculture and household-level water demand. We found different consequences of implementing either autonomous or planned adaptation measures. For instance, a decentralized scheme would drive negative implications for the entire basin, although the less water-intensive sector will be better off. On the other hand, different policy interventions would drive positive consequences for the entire basin, with the most water-intensive sector benefiting the most. These results highlight the distributional consequences across users of different adaptation measures.

     

Governance and management of local water storage in the Hindu Kush Himalayas

The people of the Hindu Kush Himalayan region face severe seasonal water shortages due to the high variability in rainfall, and the problem is likely to be exacerbated under climate change. Small-scale local water storage options offer a means of collecting monsoon precipitation to provide for agricultural and household needs over the entire year, and they help build community resilience. Proper watershed management, with due consideration of upstream–downstream linkages, and appropriate institutional arrangements are vital for this adaptation measure to work. Active participation of local users in decisions related to water allocation and community services is essential. Planned interventions should preserve the institutional arrangements of reciprocity and cooperation among community members.     

Managing Water Resources to Adapt to Climate Change: Facing Uncertainty and Scarcity in a Changing Context

Some of the most significant future efforts in water resources management will be devoted to climate change adaptation. Climate change adaptation is of special concern in regions facing water scarcity where water management is already challenged by many problems. This paper is a review of current knowledge on approaches to address water issues under uncertainty in water-scarce regions, identifying specific policy actions for climate change adaptation. The focus is on regions, like the Mediterranean, California or Australia, where water resources are well developed and have become an essential part of socioeconomic activities but are currently facing significant challenges due to their dependence on water availability to maintain living standards. We provide an overview of the expected impacts of climate change on water resources and discuss management responses based on peer-reviewed studies published over the past three decades. The adaptation choices cover a wide range of options, from adaptive demand management to utilization of remaining marginal water sources. The intensification of successful measures already applied in the past is still viewed as a solution to reduce climate impacts. However, the emphasis is progressively being placed on sustainability, developing and extending the water management paradigm to include not only technical and economic criteria, but also ecological and social considerations.     

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.

     

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.     

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.     

Policy options for promoting urban–rural cooperation in water management: a review

As most cities share their water basins with rural areas, an efficient and environmentally sensible urban water management system needs to consider the interplay between urban and rural water uses. This article analyses the three main challenges at this interface: increased competition for water resources (scarcity); flood management (abundance); and freshwater quality conservation (pollution). The merit of potential policy options is discussed from an economics perspective, taking examples from successful experiences in cities around the world. The benefits and challenges arising from enhanced coordination and integration between urban and rural water management are highlighted.     

Managing Adaptation of Urban Water Systems in a Changing Climate

Current evidence is that climate change is occurring, it is largely manmade and it will have significant implications for human civilisation. Australia is particularly vulnerable to the anticipated effects of climate change, creating major challenges for water resource management and water supply security. Climate change adaptation offers a means by which we can reduce our exposure to future climate change risks, whilst at the same time exploiting any potential benefits that may arise from climatic changes. This review outlines the current major climate change adaptation challenges facing the water supply industry at large, with a particular focus on these challenges in an Australian context. It also aims to highlight the critical knowledge gaps and strategies required to assist in the formulation of adaptation responses to the range of potential impacts on water infrastructure and future water security. A diverse range of management and assessment techniques are used by relevant professions in industry. Here, an adaptive management approach is presented highlighting the important information required for robust assessment.     

Integrated Assessment of no-Regret Climate Change Adaptation Options for Reservoir Catchment and Command Areas

The need for credible, salient and legitimate climate change adaptation options in the water sector, which target location specific adaptation requirements, is well recognized. In developing countries, the low-hanging fruit; no-regret options, should be identified with stakeholders and assessed against future changes in water availability and demand, for comparing effectiveness and robustness. Such integrated basin-scale assessments, including reservoir catchment and command areas, can suitably inform adaptation decision-making. In this study, we integrate participatory and modelling approaches for evaluation of reservoir catchment and command area no-regret options addressing water availability and demand in the Kangsabati river basin. Through multi-level stakeholder workshops we identify and prioritize options, followed by evaluation of two reservoir catchment options; check dams and increasing forest cover and three reservoir command options; changing cropping pattern, traditional ponds and waste water reuse, using the Water Evaluation And Planning (WEAP) model. We use four high resolution (~25 km) regional climate model simulations of future climatic factors, along with non-climatic factors affecting water demand, for forcing WEAP. We find that options have varied ability in addressing adaptation requirements. Amongst catchment options, increasing forest cover addresses adaptation requirements more suitably than check dams, while in the command areas we observe mixed abilities of options, leading to the inference that combining complementary options may be a more useful strategy. We conclude by discussing our experiences with this approach in a developing country context, in terms of benefits, limitations, lessons learnt and future research directions.     

Multi-criteria Approach for Selection of Green and Grey Infrastructure to Reduce Flood Risk and Increase CO-benefits

Continuous changes in climate conditions combined with urban population growth pose cities as one of the most vulnerable areas to increasing flood risk. In such an atmosphere of growing uncertainty, a more effective flood risk management is becoming crucial. Nevertheless, decision-making and selection of adequate systems is a difficult task due to complex interactions between natural, social and built environments. The combination of green (or sustainable) and grey (or traditional) options has been proposed as a way forward to ensure resilience in advance of extreme events, and at the same time to obtain co-benefits for society and the environment. The present paper describes a novel method for selection of urban flood measures, based on a multi-criteria analysis that includes flood risk reduction, cost minimization and enhancement of co-benefits. The aim of this method is to assist decision makers in selecting and planning measures, which afterwards can be part of either high level scoping analysis or more complex studies, such as model based assessment. The proposed method is implemented within a tool which operates as a standalone application. Through this tool, the method has been applied in three study cases. The findings obtained indicate promising potential of the method here introduced.     

Urban stream overflow probability in a changing climate: Case study of the Seoul Uicheon Basin,Korea

Flooding from the overflow of rivers and streams can cause major disruption in urban areas that is likely to have significant effects on human activities and the environment. Such consequences could be exacerbated by enhanced levels of precipitation resulting from future climate change. Various options are available for responding to flooding; however, further studies are needed to improve the design flood criteria in order to cope with the uncertainties of a changing climate. This study investigated an improved methodology for the evaluation of the overflow probability of urban streams. This was achieved through the application of Monte Carlo simulations (MCSs) and climate change scenarios that incorporated an increased probability of overbank flooding. An estimation of the probability of future rainfall in the Uicheon Basin of Korea, using chaos disintegration with regional climate model (RCM) scenario data, indicated a projected increase of 4.4%–9.6%. The results for 100-year flooding under projected conditions of climate change, based on a hydrologic overflow inundation model, showed that flooded areas could increase by 58.1% compared with current levels, depending on the climate change scenarios. However, forecasts based on MCSs indicated that extreme rainfall could increase by 94.9%. Thus, an overflow analysis that reflects both extreme hydrologic events and more frequent flooding due to climate change could provide a more reliable means of forecasting extreme events, as well as helping to prevent natural disasters associated with unexpected extreme flooding. The results obtained in this study would provide useful data for stakeholders and decision makers to both enhance policy standards and formulate measures to reduce the risk of urban flooding within the context of a changing climate.     

基于模糊系统分析的水生态安全评价研究——以北方四市为例

针对城市水生态安全评价的不确定性与模糊性特征,运用基于模糊系统分析的方法对北方四城市的水生态安全评价指标体系分析并优化,并对四城市水生态安全状况进行模糊综合评价研究,以揭示影响城市水生态安全的主要影响因子。结果表明,北方四城市的水生态安全受人类经济社会活动影响较大,利用本方法进行水生态安全评价是合理可行的,可为区域水生态安全管理提供科学依据。     

Impacts of Global Climate Change Scenarios on Water Supply and Demand in Jordan

Abstract

The potential impact of global climate change is one of the least addressed factors in water resources planning in developing countries. The potential impacts of climate change are examined for Jordan, where a methodology is presented for improved management of water demand under the uncertainties associated with climate change. A temperature/precipitation sensitivity model is constructed and combined with water demand forecasts to project deficits for the year 2020. Deficit reducing options are then evaluated in terms of social and economic viability. The study concludes that only some of the deficits may be alleviated, illustrating the significance of considering climate change in planning for countries that already experience water imbalances.     

堤防建设如何与城市发展相结合探析

结合广西城市堤防建设发展状况,对城市堤防工程防洪标准,与城市建设、城市景观及城市其他基础设施之间的关系等问题进行了分析,指出城市堤防建设在保证防洪安全功能的条件下,应结合城市的发展与定位,跳出单一的防洪建设范畴,与城市建设、环境美化、景观建设融为一体,多功能、全方位的协调发展,才能更好发挥其经济、社会和环境效益.     

Utilising integrated urban water management to assess the viability of decentralised water solutions

Cities worldwide are challenged by a number of urban water issues associated with climate change, population growth and the associated water scarcity, wastewater flows and stormwater run-off. To address these problems decentralised solutions are increasingly being considered by water authorities, and integrated urban water management (IUWM) has emerged as a potential solution to most of these urban water challenges, and as the key to providing solutions incorporating decentralised concepts at a city wide scale. To incorporate decentralised options, there is a need to understand their performance and their impact on a city's total water cycle under alternative water and land management options. This includes changes to flow, nutrient and sediment regimes, energy use, greenhouse gas emissions, and the impacts on rivers, aquifers and estuaries. Application of the IUWM approach to large cities demands revisiting the fundamental role of water system design in sustainable city development. This paper uses the extended urban metabolism model (EUMM) to expand a logical definition for the aims of IUWM, and discusses the role of decentralised systems in IUWM and how IUWM principles can be incorporated into urban water planning.     

城市河流综合治理开发与效益分析——以临沂市小涑河为例

城市河流综合治理对滨水城市的社会经济发展和生态环境建设具有重要意义。以临沂市小涑河为例,论述了城市河流综合治理开发可采取的措施,并通过建立评价指标来分析治理后所带来的社会、经济和生态环境效益。结果显示,治理后的小涑河,基本实现了"蓄一河清泉水、建一条经济带、成一道景观线"的社会、经济和生态发展目标。为同类城市河流的综合治理开发提供了理论和实践经验。