英国气候变化风险评估

英国政府目前正在着手对因气候变化造成的风险进行全面评估,并将制订适应气候变化的计划,以便为应对气候变化提供明确的指导,提高各行业适应气候变化的能力。以水的供需平衡为例,简要阐述了风险评估的过程与结果。结果表明,未来需水量会随温度的上升而增加。因此,有必要采取节约用水和提高用水效率等措施。     

An Assessment of Climate Change,Water Resources,and Policy Research

ABSTRACT

A significant climate change can affect water resources and result in social and/or environmental impacts that can become policy issues. Review of the research in this emerging field of climate, water and policy reveals certain key issues that affect the transfer of information to policymakers. It also reveals the necessity for interdisciplinary analyses, a lack of information about parts of the hydrologic cycle, and the limited views many hydrologists have about climate changes and how to deal with them. The emphasis of recent research has been on effects on precipitation of CO, induced global warming on how climate changes might alter extreme events (droughts and floods), the relationship of climate alterations and water quality, and development of methods to better ascertain linkages of climate, water, and society. Policymakers attempting to address the effects of climate change on water resources generally ask six questions including: (1) the type of climate change apt to occur; 2) the changes beyond our recent (100-year) experience; 3) whether the changes can be predicted; 4) the certainty of change/s predicted; 5) the effects (social and environmental) that will occur; and (6) the potential adjustments needed.

Efforts to address adequately these questions are often hindered by four problem areas that need attention. First, climate impacts research is still in the developmental stage. Second, knowledge about certain hydrologic cycle variables is lacking and in particular, the interactions between climate and water quality. Third, many hydrologists assume stationarity in climate and find it difficult to accept and utilize climate change concepts. Finally, the impact of information on climate-water issues on the policy process is less than adequate often because scientists poorly understand the policy process.     

Assessment of Climate Change Impacts on Water Resources in the Somme River Basin (France)

Modelling the impacts of climate change on water resources in the Somme watershed in northern France is investigated with a multimodel ensemble to probe the sensitivity of hydrologic response to uncertainties in climate projections provided by general circulation models. At the Somme watershed scale, the average decrease in predicted recharge from seven climate models is ?18.7%. However, significant disparities appear between simulation results for different climate models. These variations are bounded between ?30.4% for the most pessimistic model and???5.6% for the most optimistic model. Moreover, seasonal gaps are markedly important. For all climate models, the impacts on groundwater levels would be greater on plateaus than in humid valleys. The water level changes would be on the order of ?10 m on the plateaus for five climate models and between 0.2 m and 0.5 m in humid valleys. The impacts of two other climate models on water levels are rather low. In addition, the monthly average discharge of the Somme River and its tributaries is predicted to decrease by 2065. The seven-model average shows that the low outlet flow rate to the Somme basin would be reduced by 23% but with disparities between models. The decrease would be more severe in the Avre basin, with the minimal discharge reduced by 32%. This study is a first step towards addressing uncertainties in climate models such that an adaptive watershed management strategy could be devised for water resource managers.

     

Watershed Modeling to Assessing Impacts of Potential Climate Change on Water Supply Availability

Climate change could have impacts on hydrologic systems threatening, availability of water supply resources. In Illinois, regional water supply planning efforts are attempting to better understand potential impacts on low flow and surface water availability through analysis of hydrologic sensitivity to a range of climate scenarios. This paper explores the development, calibration and validation of Fox River watershed model using the soil and water assessment tool (SWAT) and the model’s application to assess impacts of potential climate change. The watershed model is calibrated and validated using daily flow records at three gauging stations. Automatic model calibration followed by manual refinement of parameter values was performed. Calibration results were generally good for monthly and annual time step but only satisfactory for daily simulations. Based on simulations of global climate models produced for IPCC fourth assessment report, climate scenarios were prepared by the Illinois State Water Survey for water supply planning initiatives in north-east and east-central Illinois. These scenarios showed ranges of temperature change between 0°C to +3.3°C and annual precipitation changes between −127 to +127 mm in the next 50 years, excluding the 5% extreme ends of those climate model simulations considered. Changes in climate were reflected using adjustments to the historical record, instead of using direct outputs from individual climate models. The watershed model was used to assess the impact of potential climate change. Application results indicate that annual precipitation change of 127 mm on average increases annual water yield and 7-day low flows by 28% and 19%, respectively. In contrast, a temperature change of +3.3°C results in average reductions of annual water yield by 13% and 7-day low flows by 10%. Seasonal effects were investigated through evaluation of changes in average monthly flows. Increasing precipitation resulted in significant changes in streamflows in late summer and fall months where as increasing temperature greatly affects winter flows due to snowmelt. The key implication is that climate change-induced variability of streamflows could have major impacts on water supply availability in the Fox River watershed and in particular, increased periods of drought could result in deficit of supplies during seasons of peak water use. It must be noted that this analysis does not examine the potential impacts of population growth and water use on water supply availability, which are also expected to have substantial influences in the region.     

Assessment of Water Resources Vulnerability and Adaptation to Climate Change

This paper provides an overview of the 'standard' methodology developed for the United States Country Studies Program on the Assessment of Water Resources Vulnerability and Adaptation to Clim ate Change. The methodology is described in more detail in accompanying articles in this issue. A standard methodology was developed for two reasons. First, for countries with little or no experience in hydrologic and water resources modelling, it provided a simple, yet appropriate set of modelling tools that could be quickly learned and applied with a limited data set. Second, it provided a consistent methodology for synthesizing results for regional and global assessments as well as cross-country and cross-regional comparisons.     

气候变化对流域水资源影响评价中的不确定性问题

<正>确评价气候变化背景下的流域水资源是实现其可持续性开发利用的基础,气候变化对流域水资源影响的评价一般采取气候情景驱动水文循环模型的方法。由于气候系统和水文循环过程的复杂性,该方法在气候情景、水文循环模拟及评价过程中存在很大的不确定性。提高流域气候情景预测精度和完善影响评价模型是降低气候变化影响评价结果不确定性的主要方式。本文介绍了气候变化对流域水资源影响的一般评价方法,分析了影响评价结果不确定性的因素,并讨论了降低评价结果不确定性的方式。     

The Impacts of Climate Variability and Future Climate Change in the Nile Basin on Water Resources in Egypt

This paper describes the application of hydrologic models of the Blue Nile and Lake Victoria sub-basins to assess the magnitude of potential impacts of climate change on Main Nile discharge. The models are calibrated to simulate historical observed runoff and then driven with the temperature and precipitation changes from three general circulation model (GCM) climate scenarios. The differences in the resulting magnitude and direction of changes in runoff highlight the inter-model differences in future climate change scenarios. A 'wet' case, 'dry' case and composite case produced +15 (+12), -9 (-9) and + 1(+7) per cent changes in mean annual Blue Nile (Lake Victoria) runoff for 2025, respectively. These figures are used to estimate changes in the availability of Nile water in Egypt by making assumptions about the runoff response in the other Nile sub-basins and the continued use of the Nile Waters Agreement. Comparison of these availability scenarios with demand projections for Egypt show a slight surplus of water in 2025 with and without climate change. If, however, water demand for desert reclamation is taken into account then water deficits occur for the present-day situation and also 2025 with ('dry' case GCM only) and without climate change. A revision of Egypt's allocation of Nile water based on the recent low-flow decade-mean flows of the Nile (1981-90) shows that during this period Egypt's water use actually exceeded availability. The magnitude of 'natural' fluctuations in discharge therefore has very important consequences for water resource management regardless of future climate change.     

Evaluation of Water Resources Management Strategies to Overturn Climate Change Impacts on Lake Karla Watershed

The effects of climate change on meteorology, hydrology and ecology have become a priority area for research and for water management. It is crucial to identify, simulate, evaluate and, finally, adopt water resources management strategies to overturn the impacts of climate change. This paper is dealing with the assessment of climate change impacts on the availability of water resources and the water demands and the evaluation of water resources management strategies in the Lake Karla watershed, central Greece and it is a contribution to the “HYDROMENTOR” research project. The outputs of the Canadian Centre for Climate Modelling Analysis Global Circulation Model CGCM3 were downscaled using a statistical hybrid method to estimate monthly precipitation and temperature time series for present and future climate periods. The analysis was conducted for two future periods 2030–2050 and 2080–2100 and three SRES scenarios (A2, A1B and B1). The surface water and groundwater have been simulated for present and future climate periods using a modelling system, which includes coupled hydrologic models. Two operational strategies of hydro-technical project development are coupled with three water demand strategies. Overall, eight water management strategies are evaluated for present climate conditions and twenty four water management strategies for future climate conditions have been evaluated. The results show that, under the existing water resources management, the water deficit of Lake Karla watershed is large and it is expected to become critical in the future, even though the impact of climate change on the meteorological parameters is very moderate.     

Economic and Social Adaptations to Climate Change Impacts on Water Resources: A Case Study of Egypt

Literature is em erging on the adaptation of water resource systems to climate change (Stakhiv, 1995; Strzepek & Sm ith, 1995). These adaptations are generally discussed at either the sectoral or at the micro-economic level. However, little has been said about the macro-economic adaptation to shifts in water resources due to climate change. This lack of discussion is primarily due to the fact that very few countries have been able to make a com prehensive national assessment of climate change im pacts on water resources at the same scale as a macro-economic modelling analysis. W here macro-economic m odelling has been done, the water resource systems are highly regional and difficult to aggregate to a single national im pact. W here homogenous water resources systems exist, m acro-econom ic impact modelling has not incorporated water resources. This paper examines the macro-economic adaptations to climate change im pacts on national water resources. Because of the problems listed above, a 'laboratory' country was chosen. Egypt has a single water resource- the Nile- and a substantial portion of Egypt's economic activity is related to this river. Changes in Nile discharges can be directly linked to macro-economic accoun ts, yet obviously more strongly linked to the agricultural sector. For this reason, a macro-economic m odel has been used which contains a disaggregated agricultural sector and a highly aggregated non-agricultural sector. A discussion of technical adaptations to climate change-induced reductions in Nile flows is presented. W hile these technical adaptations of the N ile are important, the macro-economic impacts of decreases or increases in Nile River discharge are shown to be minor compared with fu ture socioeconomic development and domestic policy strategies. The paper concludes with a discussion of anticipatory econom ic and policy adaptations that appear to be more significant than technical adaptations for Egypt.     

Impacts of Climate Change on Water Resources Availability and Agricultural Water Demand in the West Bank

Global climate change is predicted as a result of increased concentrations of greenhouse gasses in the atmosphere. It is predicted that climate change will result in increasing temperature by 2 to 6°C and a possible reduction of precipitation of up to 16% in the Mediterranean basin. In this study, the West Bank is taken as a case study from the Mediterranean basin to evaluate the effects of such climate change on water resources availability and agricultural water demands. Due to the uncertainty in climate change impacts on temperature and precipitation, a number of scenarios for these impacts were assumed within the range of predicted changes. For temperature, three scenarios of 2, 4 and 6°C increase were assumed. For precipitation, two scenarios of no change and 16% precipitation reduction were assumed. Based on these scenarios, monthly evapotranspiration and monthly precipitation excess depths were estimated at seven weather stations distributed over the different climatic and geographical areas of the West Bank. GIS spatial analyses showed that the increase in temperature predicted by climate change could potentially increase agricultural water demands by up to 17% and could also result in reducing annual groundwater recharge by up to 21% of existing values. However, the effects of reduced precipitation resulting from climate change are more enormous as a 16% reduction in precipitation could result in reducing annual groundwater recharge in the West Bank by about 30% of existing value. When this effect is combined with a 6°C increase in temperature, the reduction in groundwater recharge could reach 50%.     

Climate Change Impacts on the Water Supply of Thessaloniki

This paper examines the assessment of the impacts of climate change on water resources in the Aliakmon river basin, Northern Greece, and on some critical water management issues, such as reservoir storage and water supply of the city of Thessaloniki. A monthly conceptual water balance model was calibrated using historical hydrometeorological data. This model was applied to estimate runoffs in the entrance of the Polyfyto reservoir under two different equilibrium scenarios (UKHI, CCC) referring to 2050. Reduction of the mean annual runoff, mean winter runoff and summer runoff would occur. By using these scenarios, the sensitivity of the risk associated with the water supply for the city of Thessaloniki was evaluated under conditions of altered runoff. Increases of the risks associated with the annual quantities of water supply were observed, particularly under the UKHI scenario.     

Assessment of Future Climate Change Impacts on Water Resources of Upper Sind River Basin, India Using SWAT Model

A study has been conducted to assess future climate change impacts on water resources of the Upper Sind River Basin using Soil Water Assessment Tool. Sequential uncertainty fitting (SUFI-2) algorithm has been applied for model calibration and uncertainty analysis. Monthly observed stream flows matched well with simulated flows with respect to p-factor, d-factor, Correlation coefficient and Nash-Sutcliffe coefficients with values of 0.73, 0.42, 0.82, 0.80 during calibration (1992–2000) and 0.42, 0.36, 0.96, 0.93 during validation (2001–2005) respectively. PRECIS generated outputs under IPCC A1B Scenarios for Indian conditions corresponding to the baseline (1961–1990), midcentury (2021–2050) and endcentury (2071–2098); extracted by Indian Institute of Tropical Meteorology, Pune (India) have been used for the study. It has been found from the model results that the average annual streamflow could increase by 16.4 % for the midcentury and a significant increase of 93.5 % by the endcentury. The results also indicate that streamflow may rise drastically in monsoon season, but will decrease in non-monsoon season due to the projected future climate change.     

Climate Change Impacts on Water Resources and Lake Regulation in the Vuoksi Watershed in Finland

The impacts of climate change on hydrology and water resources in the Vuoksi watershed in eastern Finland were studied in order to assess the possibilities to adapt lake regulation to the projected changes. A conceptual watershed model and several climate scenarios were used to estimate the effects of climate change on three lakes in the Vuoksi watershed for 2010–2039, 2040–2069 and 2070–2099. The adaptation possibilities were studied by using alternative regulation strategies. In Lake Pielinen the impacts of these water level changes on social, economic and ecological indicators were assessed with two different outflow strategies. According to the results, climate change will alter snow accumulation and melt and therefore cause large seasonal changes in runoff and water levels. Runoff and water levels will decrease during late spring and summer and increase during late autumn and winter. In some lakes current calendar-based regulation practices and limits, which have been developed based on past hydrology, may not be appropriate in the future. Modifying the regulation practices and limits is a necessary and effective way to adapt to climate change.     

气候变化下水资源适应性对策的定量评估方法

论述了气候变化背景下水资源管理所面临的主要问题和适应性管理的基本内涵,介绍了应对气候变化影响的水资源适应性管理的国内外研究进展,梳理归纳了目前分析评价适应性管理对策的几种不同方法,认为定量分析适应性对策的经济效益至为关键,成本效益分析的步骤主要包括:①点绘实物量基线曲线;②点绘经济量基线曲线;③点绘过去适应性管理变化曲线;④分析气候变化引发的变化;⑤适应性管理获得的效益变化。     

Quantifying the Urban Water Supply Impacts of Climate Change

The difference in timing between water supply and urban water demand necessitates water storage. Existing reservoirs were designed based upon hydrologic data from a given historical period, and, given recent evidence for climatic change, may be insufficient to meet demand under future climate change scenarios. The focus of this study is to present a generally applicable methodology to assess the ability of existing storage to meet urban water demand under present and projected future climatic scenarios, and to determine the effectiveness of storage capacity expansions. Uncertainties in climatic forcing and projected demand scenarios are considered explicitly by the models. The reservoir system in San Diego, California is used as a case study. We find that the climate change scenarios will be more costly to the city than scenarios using historical hydrologic parameters. The magnitude of the expected costs and the optimal investment policy are sensitive to projected population growth and the accuracy to which our model can predict spills.     

Climate Change Water Resources Planning Impacts Incorporating Reservoir Surface Net Evaporation Fluxes: A Case Study

The majority of published studies on the impacts of climate change on reservoired water resources systems have concentrated on the influence of the climate- change-modified inflow series. However, for reservoirs the direct net evaporation (i.e. evaporation less rainfall) fluxes on the reservoir surface are also affected by climate change and, depending on the magnitude of the change, could have significant effects on the assessed impacts. In this study, we have performed reservoir storage-yield-reliability planning analyses on two multiple reservoir systems, one in England and the other in Iran, to investigate the possible effects of reservoir surface net evaporation flux for both baseline and climate-change conditions. The results showed that, under baseline conditions, consideration of net evaporation will require lower storages for the English systems and higher storages for the Iranian systems. The practical significance of this is that English systems analysed without consideration of surface fluxes represent an over-design which can provide a buffer against future shortages, whereas the under-design caused by ignoring surface fluxes in the Iranian systems will exacerbate the problem of such shortages. Perturbing the baseline inflow and climatological time-series data using a number of recently published climate-change scenarios produced different impacts at high and low yields for both systems. Possible explanations are offered for these impacts and suggestions are made for further studies.     

气候变化对水的影响研究及其科学问题

全球变暖是目前最重要的环境问题之一,基于目前的相关研究成果,本文简要介绍了国际上较为常用的全球气候变化情景及我国未来的气候变化情势,着重论述了我国水资源系统对气候变化的敏感性以及未来气候变化情势下我国的水资源情势。最后,针对目前评价结果中存在的问题及薄弱环节,提出了在下一步气候变化对水影响研究中需要重点解决的科学问题。     

气候变化对大型水利工程的影响

气候变化将导致流域降雨径流关系、水文极端事件的大小和频率发生改变，影响大型水利工程的建设标准、规模和运行规程。以三峡工程和南水北调工程为例，介绍了气候变化对大型水利工程设计、运行等方面的可能影响。     

Characterisation of the Sensitivity of Water Resources Systems to Climate Change

This paper offers a methodology that enables characterisation of the behaviour of water resources systems under the impact of climate change through assessment of sensitivity patterns in a wide range of hydrologic variations produced by such change. Analysis is based on the application of two indicators that, in turn, draw on the results of a system optimisation model. Under this methodology the potential sensitivity of water resources systems in the cases of different climate projections are visualised, allowing those systems that require special attention in their adaptation to climate change to be identified. The methodology is applied to three basins located in Spain: Guadalquivir, Ebro and the Spanish part of the international basin Duero.     

中国东部季风区水资源脆弱性评价

以中国东部季风区的八大流域为例,从水资源供需安全的角度,对2000年水资源状况和未来气候变化情景下的水资源脆弱性进行了评价。结果表明:海河流域是中国水资源的严重脆弱区,黄河和淮河均处于高度脆弱状态,辽河流域、松花江流域、长江流域、东南诸河和珠江流域绝大部分地区处于中度脆弱状态;未来气候变化使得中国东部季风区八大流域的水资源脆弱性均明显加重,黄淮海流域均上升到严重脆弱状态,对气候变化极度敏感,必须采取相应措施来积极应对气候变化对流域水资源的不利影响。