Global Studies
Regional Studies
Extreme Weather
CLIMATE CHANGE AND HYDROLOGIC RESOURCES - ABSTRACTS

Regional and Country-Level Studies

Africa

K. J. Sene, E. L. Tate and F. A. K. Farquharson. 2001. "Sensitivity Studies of the Impacts of Climate Change on White Nile Flows," Climatic Change, Vol. 50, No. 1-2, July, pp. 177-208.
ABSTRACT: Several exploratory studies are presented on the sensitivity of the water balance of the White Nile to climate change, using both observed and stochastic time series to drive the models. Example results are presented using various assumed climate change scenarios and results from a General Circulation Model (GCM). The relative merits and shortcomings of each modelling approach are also discussed. A simple analytical model for Lake Victoria is also used to illustrate some of the overall features of the lake's likely response. Particular difficulties with the White Nile system are that, due to the huge area of open water in the basin, transient responses to short-lived events can occur over timescales comparable with those for which long term climate change impacts are being studied, and predicted changes in flows are extremely sensitive to estimates for the rainfall and evaporation at lake and swamp surfaces. Of the modelling approaches considered, the network simulation approach with stochastic inputs is recommended as a way of smoothing out these transient effects, and assessing the uncertainty in the results due to inaccuracies in the data, the model parameters and the climate change predictions. The paper concludes with a brief discussion of some other areas of uncertainty in the hydrological modelling of White Nile flows and possible alternative external forcing mechanisms for flows in the next few decades.

Feddema, Johannes J. 1999. "Future African Water Resources: Interactions between Soil Degradation and Global Warming," Climatic Change, Vol. 42, No. 3, July, pp. 561-596.
ABSTRACT: This study uses a well-established water balance methodology to evaluate the relative impact of global warming and soil degradation due to desertification on future African water resources. Using a baseline climatology, a GCM global warming scenario, a newly derived soil water-holding capacity data set, and a worldwide survey of soil degradation between 1950 and 1980, four climate and soil degradation scenarios are created to simulate the potential impact of global warming and soil degradation on African water resources for the 2010-2039 time period. Results indicate that, on a continental scale, the impact of global warming will be significantly greater than the impact of soil degradation. However, when only considering the locations where desertification is an issue (wet and dry climate regions), the potential effects of these two different human impacts on local water resources can be expected to be on the same order of magnitude. Drying associated with global warming is primarily the result of increased water demand (potential evapotranspiration) across the entire continent. While there are small increases in precipitation under global warming conditions, they are inadequate to meet the increased water demand. Soil degradation is most severe in highly populated, wet and dry climate regions and results in decreased water-holding capacities in these locations. This results in increased water surplus conditions during wet seasons when the soil's ability to absorb precipitation is reduced. At the same time, water deficits in these locations increase because of reduced soil water availability in the dry seasons. The net result of the combined scenarios is an intensification and extension of drought conditions during dry seasons.

Egypt

Strzepek, Kenneth M., and David N. Yates. 2000. "Responses and Thresholds of the Egyptian Economy to Climate Change Impacts on the Water Resources of the Nile River," Climatic Change, Vol. 46, No. 3, August, pp. 339-356.
ABSTRACT: Are there "thresholds" in greenhouse gas (GHG) concentrations above which associated climate change impacts become economically, socially or environmentally unacceptable? If thresholds exist, then emissions might be limited in such a way that GHG concentrations are not exceeded. Environmental, social, and economic systems should be examined in order to determine these threshold levels.
This paper addressed the potential impacts of climate change on the water resources of the Nile River and associated impacts on the Egyptian economy through the use of a recursively dynamic general equilibrium model. The model was used to examine both economy-wide and sectoral impacts, and impacts on social and national policy indicators under various economic growth and climate change scenarios. Macro-economic indicators such as Gross Domestic Product (GDP) showed that strict economic thresholds, characterized by discontinuities in the response function, did not occur. This was because autonomous economic adjustments generated a smooth socioeconomic transition over the 70-year simulation period. The economy underwent a gradual structural transformation, as capital and resources were moved from cropped agricultural to both the livestock and the non-agricultural sectors. Under "wet" climate scenarios, surplus water beyond 75 billion cubic meters (BCM) remained unused, as the marginal value of water dropped to zero and other resource constraints limited agricultural growth. For drier scenarios (below 75 BCM), water was a constraint to agricultural production into the 21st century, as resources were diverted to less water demanding crops and the livestock and non-agricultural sectors. The reduced water scenarios showed agriculture declining in its total share of GDP, burdening the agricultural wage earner. Egypt increased its dependence on imports to meet food demand, dramatically decreasing grain self-sufficiency, while increasing protein self-sufficiency. If national policy requires a certain level of food self-sufficiency, then these metrics could be used in defining policy-based thresholds.

Ethiopia

Hailemariam, Kinfe. 1999. "Impact of climate change on the water resources of Awash River Basin, Ethiopia," Climate Research, Vol. 12, pp. 91-96.
ABSTRACT: An attempt was made to investigate the sensitivity of water resources to climate change in the Awash River Basin in Ethiopia. The climate of the basin varies from humid subtropical to arid. The basin was divided into 3 subcatchments for better resolution in calibration and simulation. Station-based meteorological data were processed to obtain areal averages necessary for the simulation. Different sets of temperature and rainfall scenarios were developed using GCM (both transient and CO2 doubling) and incremental scenarios. The IIASA integrated water balance model (WatBal) was used to estimate runoff under a changed climate. The model represents the water balance among surface outflow, subsurface outflow, and evapotranspiration. The model was calibrated using a 10 yr period (1971 to 1980), validated with the next 6 yr period (1981 to 1986), and then applied for different climate scenarios. Results of the impact assessment over the basin showed a projected decrease in runoff, which ranged from -10 to -34%, with doubling of CO2 and transient scenarios of CO2 increase (GFD3, CCCM, GF01). Sensitivity analysis based on incremental scenarios showed that a drier and warmer climate change scenario results in reduced runoff.

Asia

Ososkova T., N. Gorelkin, and V. Chub. 2000. "Water resources of central Asia and adaptation measures for climate change," Environmental Monitoring and Assessment, Vol. 61, pp. 161-166.
ABSTRACT: A large part of the central Asian region is located within the inner flow of the Aral Sea basin. The water resources are formed from renewed superficial and underground waters of natural origin, and also with returnable waters. The intensive increase of water intake in the second half of the 20th century caused practically complete assimilation of the river inflow. That was the main reason for the Aral Sea crisis. On the basis of the analysis of long periodical rows of observation by meteorological and hydrological stations, the estimation of regional water resources and calculations of changes of some components of the hydrological cycle, due to expected climate changes, are presented. Measures for adaptation in the southern part of the Aral Sea region are also considered.

Sharma, Keshav P., Charles J. Vorosmarty, and Berrien Moore III. 2000. "Sensitivity of the Himalayan Hydrology to Land-Use and Climatic Changes," Climatic Change, Vol. 47, No. 1-2, October, pp. 117-139.
ABSTRACT: Land-use and climatic changes are of major concerns in the Himalayan region because of their potential impacts on a predominantly agriculture-based economy and a regional hydrology dominated by the monsoons. Such concerns are not limited to any particular basin but exist throughout the region including the downstream plains. As a representative basin of the Himalayas, the Kosi Basin (54,000 km2) located in the mountainous area of the central Himalayan region was selected as a study area. We used water balance and distributed deterministic modeling approaches to analyze the hydrologic sensitivity of the basin to projected land-use, and potential climate change scenarios. Runoff increase was higher than precipitation increase in all the potential precipitation change scenarios applying contemporary temperature. The scenario of contemporary precipitation and a rise in temperature of 4 °C caused a decrease in runoff by two to eight percent depending upon the areas considered and models used. In the absence of climatic change, the results from a distributed water balance model applied in the humid south of the basin indicated a reduction in runoff by 1.3% in the scenario of maximum increase in forest areas below 4,000 m.

Lonergan, Stephen and Barb Kavanagh. 1991. "Climate change, water resources and security in the Middle East," Global Environmental Change, Vol. 1, No. 4, September, pp. 272-290.
ABSTRACT: The authors, focusing on the issue of water resources, set out and discuss the results of a study of the relationship between climate warming, resources and security, with an emphasis on the Middle East. The study includes an assessment of the extent to which climate warming is likely to occur in the region; the potential impacts of climate warming on key river systems; and finally a discussion of the extent to which these potential impacts are likely to contribute to political instability and conflict

Bangladesh

Mirza, M. Monirul Qader, R. A. Warrick, and N. J. Ericksen. 2003. "The Implications of Climate Change on Floods of the Ganges, Brahmaputra and Meghna Rivers in Bangladesh," Climatic Change, Vol. 57, No. 3, April, pp. 287-318.
ABSTRACT: Climate change in the future would have implications for river discharges in Bangladesh. In this article, possible changes in the magnitude, extent and depth of floods of the Ganges, Brahmaputra and Meghna (GBM) rivers in Bangladesh were assessed using a sequence of empirical models and the MIKE11-GIS hydrodynamic model. Climate change scenarios were constructed from the results of four General Circulation Models (GCMs) - CSIRO9, UKTR, GFDL and LLNL, which demonstrate a range of uncertainties. Changes in magnitude, depth and extent of flood discharge vary considerably between the GCMs. Future changes in the peak discharge of the Ganges River are expected to be higher than those for the Brahmaputra River. Peak discharge of the Meghna River may also increase considerably. As a result, significant changes in the spatial extent and depths of inundation in Bangladesh may occur. Faster changes in inundation are expected at low temperature increases than of higher temperature changes. Changes in land inundation categories may introduce substantial changes in rice agriculture and cropping patterns in Bangladesh. Reduction of increased flood hazard due to climate change requires strengthening of flood management policies and adaptation measures in Bangladesh.

Mirza, M. Monirul Qader. 2002. "Global warming and changes in the probability of occurrence of floods in Bangladesh and implications," Global Environmental Change, Vol. 12, No. 2, July, pp. 127-138.
ABSTRACT: Bangladesh is very prone to flooding due to its location at the confluence of the Ganges, Brahmaputra and Meghna (GBM) rivers and because of the hydro-meteorological and topographical characteristics of the basins in which it is situated. On average, annual floods inundate 20.5 per cent area of the country and this can reach as high as about 70 per cent during an extreme flood event. Floods cause serious damage to the economy of Bangladesh, a country with a low per capita income. Global warming caused by the enhanced greenhouse effect is likely to have significant effects on the hydrology and water resources of the GBM basins and might ultimately lead to more serious floods in Bangladesh. The use of climate change scenarios from four general circulation models as input into hydrological models demonstrates substantial increases in mean peak discharges in the GBM rivers. These changes may lead to changes in the occurrence of flooding with certain magnitude. Extreme flooding events will create a number of implications for agriculture, flood control and infrastructure in Bangladesh.

China

Aiwen, Ying. 2000. "Impact of Global Climate Change on China's Water Resources," Environmental Monitoring and Assessment, Vol. 61, No. 1, March, 187-191.
ABSTRACT:It is indicated that up to the year 2030, the annual average temperatures in China will increase by 0.88 to 1.2°C, with increments in the south less than in the north. Annual average precipitation would raise slightly, but the increment could be 4% in northeastern China. The increment of annual mean runoff could rise over 6% in the northeastern area, and decrease in the other regions 1.4 to 10.5%. The increased water shortage due to climate change could achieve 160 to 5090 million m3 in some areas of China. Financial loss due to the lack of water could reach 1300 million yuan, and up to 4400 million yuan in serious drought years in the Beijing-Tianjin-Tangshan area.

India

Mehrotra, R. 1999. "Sensitivity of Runoff, Soil Moisture and Reservoir Design to Climate Change in Central Indian River Basins," Climatic Change, Vol. 42, No. 4, August, pp. 725-757.
ABSTRACT: Climate change due to a doubling of the carbon dioxide in the atmosphere and its possible impacts on the hydrological cycle are a matter of growing concern. Hydrologists are specifically interested in an assessment of the impacts on the occurrence and magnitude of runoff, evapotranspiration, and soil moisture and their temporal and spatial redistribution. Such impacts become all the more important as they may also affect the water availability in the storage reservoirs. This paper examines the regional effects of climate change on various components of the hydrologic cycle viz., surface runoff, soil moisture, and evapotranspiration for three drainage basins of central India. Plausible hypothetical scenarios of precipitation and temperature changes are used as input in a conceptual rainfall-runoff model. The influences of climate change on flood, drought, and agriculture are highlighted. The response of hypothetical reservoirs in these drainage basins to climate variations has also been studied. Results indicate that the basin located in a comparatively drier region is more sensitive to climatic changes. The high probability of a significant effect of climate change on reservoir storage, especially for drier scenarios, necessitates the need of a further, more critical analysis of these effects.

Philippines

Jose, Aida M., and Nathaniel A. Cruz. 1999. "Climate change impacts and responses in the Philippines: water resources," Climate Research, Vol. 12, pp. 77-84.
ABSTRACT: The Philippines, like many of the world's poor countries, will be among the most vulnerable to the impacts of climate change because of its limited resources. As shown by previous studies, occurrences of extreme climatic events like droughts and floods have serious negative implications for major water reservoirs in the country. A preliminary and limited assessment of the country's water resources was undertaken through the application of general circulation model (GCM) results and climate change scenarios that incorporate incremental changes in temperature and rainfall and the use of a hydrological model to simulate the future runoff-rainfall relationship. Results showed that changes in rainfall and temperature in the future will be critical to future inflow in the Angat reservoir and Lake Lanao, with rainfall variability having a greater impact than temperature variability. In the Angat reservoir, runoff is likely to decrease in the future and be insufficient to meet future demands for water. Lake Lanao is also expected to have a decrease in runoff in the future. With the expected vulnerability of the country's water resources to global warming, possible measures to cope with future problems facing the country's water resources are identified.

Saudi Arabia

Alkolibi, Fahad M. "Possible Effects of Global Warming on Agriculture and Water Resources in Saudi Arabia: Impacts and Responses," Climatic Change, Vol. 54, No. 1-2, July, pp. 225-245.
ABSTRACT: This study assesses the possible impact of climatic change on Saudi Arabia's agriculture and water supplies using climatic change scenarios from GCMs (General Circulation Models) and related research. The resulting assessment indicates that an increase in temperature and decrease in precipitation could have a major negative impact on agriculture and water supplies in Saudi Arabia. To find signs of climatic change in Saudi Arabia a preliminary assessment of systematic changes in temperature and precipitation was made, based on the records of four Saudi weather stations. The analysis of this data, which dates back to 1961, shows no discernable signs of climatic change during the study period. Such data is, however, limited both spatially and temporally and cannot provide conclusive evidence to confirm climatic changes projected by GCMs. Nevertheless, in the light of recent climatic conditions and rapid population growth, Saudi decision-makers are urged to adopt a `no regret' policy. Ideally, such a policy would include measures to avoid future environmental or socioeconomic problems that may occur in the event of significant climatic change.

Yemen

Alderwish, Ahmed, and Mohamed Al-Eryani. 1999. "An approach for assessing the vulnerability of the water resources of Yemen to climate change," Climate Research, Vol. 12, pp. 85-89.
ABSTRACT: This paper outlines the methodology followed in the study of climate change impact on water resources in Yemen and presents initial results on the vulnerability of the water resources system. The selected modeling strategy is used for the first time in climate change assessment studies and is briefly discussed. This strategy comprised 4 interacting models: a Rainfall-Runoff Model (RRM), an Irrigation Simulation Model (ISM), a Groundwater Simulation Model (GSM), and an Economic Policy Model (EPM). Adequate indication of the water system's sensitivity to climate change in arid and semi-arid regions can only be achieved when appropriate temporal and spatial scales of the assessment are used. For instance, only hourly or daily time step models can capture climate impacts on floods of ephemeral wadis. The degree of accuracy required should also be determined by the scarcity/availability of the resources.

Australasia

Australia

Evans, Jason and Sergei Schreider. 2002. "Hydrological Impacts of Climate Change on Inflows to Perth, Australia," Climatic Change, Vol. 55, No. 3, November, pp. 361-393.
ABSTRACT: The effects of climate change due to increasing atmospheric CO2 on the major tributaries to the Swan River (Perth, Western Australia) have been investigated. The climate scenarios are based on results from General Circulation Models (GCMs) and 1000 year time series are produced using a stochastic weather generator. The hydrological implications of these scenarios are then examined using a conceptual rainfall-runoff model, CMD-IHACRES, to model the response of six catchments, which combine to represent almost 90% of the total flow entering the upper Swan River, and hence the Perth city urban area. The changes in streamflow varies considerably between catchments, exhibiting a strong dependence on the physical attributes of the catchment in question. The increase in the magnitudes of rare flood events despite significant decreases in mean streamflow levels found in some catchments emphasizes the importance of estimating changes in the nature of the precipitation (variance, length of storm and interstorm periods), along with changes in the mean, in climate change scenarios.

Europe

Middelkoop, H., K. Daamen, D. Gellens, et al. 2001. "Impact of Climate Change on Hydrological Regimes and Water Resources Management in the Rhine Basin," Climatic Change, Vol. 49, No. 1-2, April, pp. 105-128.
ABSTRACT: The International Commission for the Hydrology of the Rhine basin (CHR) has carried out a research project to assess the impact of climate change on the river flow conditions in the Rhine basin. Along a bottom-up line, different detailed hydrological models with hourly and daily time steps have been developed for representative sub-catchments of the Rhine basin. Along a top-down line, a water balance model for the entire Rhine basin has been developed, which calculates monthly discharges and which was tested on the scale of the major tributaries of the Rhine. Using this set of models, the effects of climate change on the discharge regime in different parts of the Rhine basin were calculated using the results of UKHI and XCCC GCM-experiments. All models indicate the same trends in the changes: higher winter discharge as a result of intensified snow-melt and increased winter precipitation, and lower summer discharge due to the reduced winter snow storage and an increase of evapotranspiration. When the results are considered in more detail, however, several differences show up. These can firstly be attributed to different physical characteristics of the studied areas, but different spatial and temporal scales used in the modelling and different representations of several hydrological processes (e.g., evapotranspiration, snow melt) are responsible for the differences found as well. Climate change can affect various socio-economic sectors. Higher temperatures may threaten winter tourism in the lower winter sport areas. The hydrological changes will increase flood risk during winter, whilst low flows during summer will adversely affect inland navigation, and reduce water availability for agriculture and industry. Balancing the required actions against economic cost and the existing uncertainties in the climate change scenarios, a policy of `no-regret and flexibility' in water management planning and design is recommended, where anticipatory adaptive measures in response to climate change impacts are undertaken in combination with ongoing activities.

Arnell, Nigel W. 1999. "The effect of climate change on hydrological regimes in Europe: a continental perspective," Global Environmental Change, Vol. 9, No. 1, April, p. 5-23.
ABSTRACT: This paper outlines the effects of climate change by the 2050s on hydrological regimes at the continental scale in Europe, at a spatial resolution of 0.5 × 0.5°. Hydrological regimes are simulated using a macro-scale hydrological model, operating at a daily time step, and four climate change scenarios are used. There are differences between the four scenarios, but each indicates a general reduction in annual runoff in southern Europe (south of around 50°N), and an increase in the north. In maritime areas there is little difference in the timing of flows, but the range through the year tends to increase with lower flows during summer. The most significant changes in flow regime, however, occur where snowfall becomes less important due to higher temperatures, and therefore both winter runoff increases and spring flow decreases: these changes occur across a large part of eastern Europe. In western maritime Europe low flows reduce, but further east minimum flows will increase as flows during the present low flow season - winter - rise. "Drought" was indexed as the maximum total deficit volume below the flow exceeded 95% of the time: this was found to increase in intensity across most of western Europe, but decrease in the east and north. The study attempted to quantify several sources of uncertainty, and showed that the effects of model uncertainty on the estimated change in runoff were generally small compared to the differences between scenarios and the assumed change in global temperature by 2050.

Strzepek, Kenneth M., and David N. Yates. 1997. "Climate Change Impacts on the Hydrologic Resources of Europe: A Simplified Continental Scale Analysis," Climatic Change, Vol. 36, No. 1-2, May - June, pp. 79-92.
ABSTRACT: U.S. Country Studies supported analyses of climate change impacts on water resources have been completed or are underway in the following Central and Eastern European nations: Czech Republic, Slovakia, Poland, Romania, Estonia, Russian Federation, and the Ukraine. Climate change impacts on the hydrologic resources of these countries is being performed at the river basin scale using monthly water balance models using GCM-based climate scenarios. The authors have performed a regional analysis of climate change impacts on the Hydrologic Resources of Europe using the Turc Annual Model. The regional analysis was done with GIS methodolgies using regional climate databases. The regional results were compared to the U.S. Country Studies hydrologic assessmnent results to validiate the use of this simplified methodolgy for making regional climate change assessment. Results from three countries showed acceptable performace of the annual approach . Using GCM-based climate scenarios regional analysis of potential climate change impacts on the hydrologic resources of Europe was conducted and national and regional results are presented.

Czech Republic

Dvorak, Vaclav, Josef Hladny, and Ladislav Kasparek. 1997. "Climate Change Hydrology and Water Resources Impact and Adaptation for Selection River Basins in the Czech Republic," Climatic Change, Vol. 36, No. 1-2, May - June, pp. 93-106.
ABSTRACT: The Czech Republic has a northern hemisphere Atlantic-continental type of moderate climate. Mean annual temperature ranges between 1.0 and 9.4 °C (between 8.8 and 18.5 °C in summer and between -6.8 and 0.2 °C in winter). Annual precipitation ranges between 450 mm in dry regions and 1300 mm in mountainous regions of the country. With its 2000 m3 per capita fresh water availability, the Czech Republic is slightly below average. Occasional water shortages do not usually result from general unavailability of water resources but rather from time or space variability of water supply/demand and high degree of water resources exploitation. To study potential impacts of climate change on hydrological system and water resources, four river basins have been selected in the territory of the Czech Republic: the Elbe River at Decin (50761.7 km2), the Zelivka River at Soutice (1188.6 km2), the Upa River at Ceska Skalice (460.7 km2) and the Metuje River at Marsov n. M. (93.9 km2). To simulate potential changes in runoff, three hydrological models have been applied using incremental and GCM (GISS, GFDL and CCCM) scenarios: the BILAN water balance model, the SACRAMENTO (SAC-SMA) conceptual model and the CLIRUN water balance model. The paper reviews methods applied in the study, results of the assessments and concludes with suggestions for possible general adaptation policy options where the preference is for nonstructural measures such as water conservation, efficient water demand management and protection of water resources.

Greece

Mimikou, M. A., S. P. Kanellopouloua, and E. A. Baltas. 1999. "Human implication of changes in the hydrological regime due to climate change in Northern Greece," Global Environmental Change, Vol. 9, No. 2, July, pp. 139-156.
ABSTRACT: This paper examines the impacts of climate change on various forms of water resources and on some critical water management issues. The study area is the Aliakmon river basin including three subbasins of hydrological interest located in northern Greece. A monthly conceptual water balance model was calibrated for each subbasin separately, using historical hydrometeorological data. This model was applied to estimate runoff values at the outlet of each subbasin under different climate change scenarios. Two equilibrium scenarios (UKHI, CCC) referring to years 2020, 2050 and 2100 and one transient scenario (UKTR) referring to years 2032 and 2080 were implied. It was found that reduction of the mean annual runoff and mean winter runoff values, as well as serious reduction of the summer runoff values would occur in all cases and basins. However, the runoff values for November, December and January were increased, whereas the spring runoff values were decreased, leading to a shifting of the wet period towards December and severe prolongation of the dry period. Moreover, the results indicate that all subbasins exhibit almost the same behavior under the different climate change scenarios, while the equilibrium scenarios (UKHI, CCC) seem to give more reasonable and consistent results than the transient scenario (UKTR). Finally, the negative effects of the climatically induced changes on the hydroelectric production and the water use for agricultural purposes in the study basin were assessed.

Netherlands

Dorland, C., R. S. J. Tol, and J. P. Palutikof. 1999. "Vulnerability of the Netherlands and Northwest Europe to Storm Damage under Climate Change," Climatic Change, Vol. 43, No. 3, November, pp. 513-535.
ABSTRACT: Storms occasionally bring havoc to Northwest Europe. At present, a single storm may cause damage of up to 7 billion U.S.$, of which a substantial part is insured. One scenario of climate change indicates that storm intensity in Northwest Europe could increase by 1-9% because of the doubling of CO2 concentrations in the atmosphere. A geographic-explicit, statistical model, based on recent storms and storm damage data for the Netherlands, shows that an increase of 2% in wind intensity by the year 2015 could lead to a 50% increase in storm damage to houses and businesses. Only 20% of the increase is due to population and economic growth. A 6% increase could even triple the damage. A simpler model - based on national average data and combined with a stochastic storm generator - shows that the average annual damage could increase by 80% with a 2% increase in wind intensity. A 6% wind intensity increase could lead to an average annual damage increase of 500%. The damage in Northwest Europe is about a factor 6 higher than the damage in the Netherlands. Little potential seems to exist for reducing the vulnerability to storms in the Netherlands. More attention should be given to planning at the government level for disaster relief and to the development of coping strategies.

United Kingdom

Arnell, Nigel W. 1998. "Climate Change and Water Resources in Britain," Climatic Change, Vol. 39, No. 1, May, pp. 83-110.
ABSTRACT: This paper explores the potential implications of climate change for the use and management of water resources in Britain. It is based on a review of simulations of changes in river flows, groundwater recharge and river water quality. These simulations imply, under feasible climate change scenarios, that annual, winter and summer runoff will decrease in southern Britain, groundwater recharge will be reduced and that water quality - as characterised by nitrate concentrations and dissolved oxygen contents - will deteriorate. In northern Britain, river flows are likely to increase throughout the year, particularly in winter. Climate change may lead to increased demands for water, over and above that increase which is forecast for non-climatic reasons, primarily due to increased use for garden watering. These increased pressures on the water resource base will impact not only upon the reliability of water supplies, but also upon navigation, aquatic ecosystems, recreation and power generation, and will have implications for water quality management. Flood risk is likely to increase, implying a reduction in standards of flood protection. The paper discusses adaptation options.

Latin America

Yates, David N. 1997. "Climate change impacts on the hydrologic resources of South America: an annual, continental scale assessment," Climate Research, Vol. 9, No. 1-2, December 29, pp. 147-155.
ABSTRACT: Two empirical annual runoff models which represent point estimates of river basin discharge were used for assessing the potential impact of climate change on runoff over South America. The first model is an annual regression relationship which relates temperature and precipitation to basin discharge. The second relationship is based on observed climatological variables and relates annual precipitation and potential evapotranspiration to runoff. A Geographic Information System (GIS) was used to implement these annual models in order to assess runoff on a 0.5° [lozenge] 0.5° grid over South America using mean annual temperature, precipitation, and computed potential evapotranspiration images. Annual changes in precipitation (percent change) and temperature (absolute change) were gathered from 4 Global Circulation Models (GCMs) and were used to derive new runoff estimates. Generally, these climate change scenarios consistently showed increases in runoff over the northwest and southern regions of South America, while the central and northeast regions were a mixture of increases and decreases depending on the GCM scenario. Comparisons with detailed, basin level models with shorter time-steps are necessary to validate the use of these annual approaches for continental scale assessment.

Argentina

Carril, Andrea F., Moira E. Doyle, Vicente R. Barros, and Mario N. Núñez. 1997. "Impacts of climate change on the oases of the Argentinean cordillera," Climate Research, Vol. 9, No. 1-2, December 29, pp. 121-129.
ABSTRACT: Until the mid 1970s a negative trend in the river flow values in the Argentinean provinces of San Juan and Mendoza (Cuyo region) was observed. The prevailing critical conditions and their economic and social impacts provide a basis for the characterization of an adverse climate change scenario for the region. The causes of the early 1970s scenario were assessed in this study in order to determine whether or not it could be related to global warming conditions. River flows are dependent on winter precipitation and on accumulated snow on the Andes cordillera. The lowest negative river flow value observed can be explained by the behaviour of the Southern Oscillation Index (SOI) and other macroclimatic parameters, such as sea-surface temperatures (SSTs) of the Atlantic and Pacific oceans. It was observed that the SOI is the parameter most strongly correlated with river flows. The highest correlation was found for the 2.4- and 4.8-yr frequencies and the low 43-yr frequency. Consequently, the low river flow values observed during the early 1970s are considered to be related to a low-frequency minimum of the El Niño-Southern Oscillation (ENSO), as well as to the behaviour of sea-surface temperature close to the coast of Chile. Both factors are associated with a minimum hemispheric temperature value. It is concluded that the 1960-70 drought in the oases of the cordillera was not linked to a warm period. Therefore it is not appropriate, at least for the time being, to state that the oases will experience drought conditions under a global warming scenario with temperature increases of a few degrees.

Mexico

Magaña, Víctor O., and Cecilia Conde. 2000. "Climate and Freshwater Resources in Northern Mexico: Sonora, a Case Study," Environmental Monitoring and Assessment, Vol. 61, No. 1, March, 167-185.
ABSTRACT: An analysis of current trends in water availability in the Mexican border state of Sonora is presented to illustrate what may be faced under climate change conditions. Precipitation, streamflow and even dam levels data are examined to estimate what changes have been experienced in recent decades. There are indications that the more frequent occurrence of El Niño/Southern Oscillation (ENSO) events have resulted in more winter precipitation and consequently in a slight increase in water availability in northwestern Mexico. However, water demands grow much faster than such trends in water availability, mainly due to a rapid increase in population in urban areas and in socio-economic activities such as those related to agriculture, industry and power generation. Some strategies to adapt or mitigate climate change conditions are proposed.

Mendoza, Víctor M., Elba E. Villanueva, and Julián Adem. 1997. "Vulnerability of basins and watersheds in Mexico to global climate change," Climate Research, Vol. 9, No. 1-2, December 29, pp. 139-145.
ABSTRACT: Some conclusions on the vulnerability of hydrologic regions in Mexico to future changes in climate can be drawn from the application of regional-scale thermal-hydrological models. Climate changes induced by the doubling of atmospheric CO2 have been predicted for the year 2050 by general circulation models (GCMs) and energy balance models (EBMs). The results obtained suggest that potential changes in air temperature and precipitation may have a dramatic impact on the pattern and magnitude of runoff, on soil moisture and evaporation, as well as on the aridity level of some hydrologic zones of Mexico. However, in other cases climate change is likely to produce a positive effect. Indices were estimated for quantifying the vulnerability of hydrologic regions and of the country as a whole. These vulnerability indices were defined according to criteria previously established for studies of this type. The indices provide information about both the hydrologic zones which are vulnerable even under current climate conditions and others which may be vulnerable to future climate changes.

Panama

Espinosa, Daly, Abril Méndez, Irina Madrid, and Raúl Rivera. 1997. "Assessment of climate change impacts on the water resources of Panama: the case of the La Villa, Chiriquí and Chagres river basins," Climate Research, Vol. 9, No. 1-2, December 29, pp. 131-137.
ABSTRACT: The goal of this study is to develop different scenarios of water resource availability in Panama under climate change-induced temperature and precipitation variability, considering a potential doubling of the atmospheric CO2 concentration in the next 100 yr. The water balance model CLIRUN3 was combined with 20 yr of basic climate information records (precipitation, potential evapotranspiration and water flow) to simulate monthly river runoff in the Chagres (Panama Canal) river basin. This basin supplies water to 25% of the country's population and is of great importance for international navigation. In the cases of the Chiriquí and La Villa river basins, 10 yr of records were used. The Chiriquí river basin is the main national source of hydropower, while the La Villa river basin is of agricultural importance. The Chagres river basin is part of the Atlantic watershed while the others belong to the Pacific watershed. The model was calibrated and run for both watersheds under scenarios with temperature increments of +1 and +2°C, while the precipitation changes considered were ±15% for the Pacific and ±20% for the Atlantic watershed. It was observed that the monthly runoff tends to decrease by 3 to 42% of the mean value in both watersheds when temperature increases and precipitation decreases. If both temperature and precipitation increase, the mean runoff value in the Pacific basins will be reduced by 5 to 35% from November to April and increased by 4 to 40% in the remaining months. In the basin of the Atlantic watershed all simulated monthly values are 3 to 50% higher than the actual mean.

North America

de Loë, Rob C., and Reid D. Kreutzwiser. 2000. "Climate Variability, Climate Change and Water Resource Management in the Great Lakes," Climatic Change, Vol. 45, No. 1, April, pp. 163-179.
ABSTRACT: Water managers always have had to cope with climate variability. All water management practices are, to some extent, a response to natural hydrologic variability. Climate change poses a different kind of problem. Adaptation to climate change in water resource management will involve using the kinds of practices and activities currently being used. However, it remains unclear whether or not practices and activities designed with historical climate variability will be able to cope with future variability caused by atmospheric warming. This paper examines the question of adaptation to climate change in the context of Canadian water resources management, emphasizing issues in the context of the Great Lakes, an important binational water resource.

Mortsch, Linda D. 1998. "Assessing the Impact of Climate Change on the Great Lakes Shoreline Wetlands," Climatic Change, Vol. 40, No. 2, October, pp. 391-416.
ABSTRACT: Great Lakes shoreline wetlands are adapted to a variable water supply. They require the disturbance of water level fluctuations to maintain their productivity. However, the magnitude and rate of climate change could alter the hydrology of the Great Lakes and affect wetland ecosystems. Wetlands would have to adjust to a new pattern of water level fluctuations; the timing, duration, and range of these fluctuations are critical to the wetland ecosystem response. Two "what if" scenarios: (1) an increased frequency and duration of low water levels and (2) a changed temporal distribution and amplitude of seasonal water levels were developed to assess the sensitivity of shoreline wetlands to climate change. Wetland functions and values such as wildlife, waterfowl and fish habitat, water quality, areal extent, and vegetation diversity are affected by these scenarios. Key wetlands are at risk, particularly those that are impeded from adapting to the new water level conditions by man-made structures or geomorphic conditions. Wetland remediation, protection and enhancement policies and programs must consider climate change as an additional stressor of wetlands.

Croley II, Thomas E., Frank H. Quinn, Kenneth E. Kunkel, and Stanley A. Changnon. 1998. "Great Lakes Hydrology Under Transposed Climates," Climatic Change, Vol. 38, No. 4, April, pp. 405-433.
ABSTRACT: Historical climates, based on 43 years of daily data from areas south and southwest of the Great Lakes, were used to examine the hydrological response of the Great Lakes to warmer climates. The Great Lakes Environmental Research Laboratory used their conceptual models for simulating moisture storages in, and runoff from, the 121 watersheds draining into the Great Lakes, over-lake precipitation into each lake, and the heat storages in, and evaporation from, each lake. This transposition of actual climates incorporates natural changes in variability and timing within the existing climate; this is not true for General Circulation Model-generated corrections applied to existing historical data in many other impact studies. The transposed climates lead to higher and more variable over-land evapotranspiration and lower soil moisture and runoff with earlier runoff peaks since the snow pack is reduced up to 100%. Water temperatures increase and peak earlier. Heat resident in the deep lakes increases throughout the year. Buoyancy-driven water column turnover frequency drops and lake evaporation increases and spreads more throughout the annual cycle. The response of runoff to temperature and precipitation changes is coherent among the lakes and varies quasi-linearly over a wide range of temperature changes, some well beyond the range of current GCM predictions for doubled CO2 conditions.

United States

Frei, A., R. L. Armstrong, M. P. Clark, and M. C. Serreze. 2002. "Catskill Mountain Water Resources: Vulnerability, Hydroclimatology, and Climate-Change Sensitivity," Annals of the Association of American Geographers, Vol. 92, No. 2, June, pp. 203-224.
ABSTRACT: We present an initial assessment of the potential impact of climate change on water supply in the Metropolitan East Coast (MEC) region of the U.S. National Assessment of the Potential Consequences of Climate Variability and Change. A version of the Thornthwaite water-balance model is applied to one of six basins in the Catskill Mountains that together provide water for approximately 10 million people in New York City and other municipalities. In addition to Thornthwaite's original soil moisture reservoir, the model includes the snow pack water reservoir of Willmott, Rowe, and Mintz (1985), a ground-water storage term, and several additional modifications. Following a review of the vulnerability of water supplies and historical hydroclimatology of this region, we estimate (1) the sensitivity of water supply to altered temperature and precipitation regimes and (2) the potential impacts of specific climate-change scenarios used by national and regional climate-change assessments. The sensitivity of runoff to temperature changes is approximately 6 percent per degree C; its sensitivity to precipitation changes is approximately 1.5 - 2 percent per percent change in precipitation, for annual mean values. Under all scenarios, rising temperatures will lead to significantly diminished water supplies unless precipitation increases dramatically. Due to disagreement between precipitation projections from different models and scenarios, projected changes in mean annual water supply range from approximately +10 percent to -30 percent by the 2080s. Under the driest scenario, water supplies under mean climatic conditions will be comparable to the worst extended drought period of the twentieth century in this region. Equally important are the likely effects on the annual cycle, which include an earlier peak runoff and a reduction of the snowpack by at least 50 percent. Considered in the context of likely increased demands, these changes may be significant.

Chen, Chi-Chung, Dhazn Gillig, and Bruce A. McCarl. 2001. "Effects of Climatic Change on a Water Dependent Regional Economy: A Study of the Texas Edwards Aquifer," Climatic Change, Vol. 49, No. 4, June, pp. 397-409.
ABSTRACT: Global climate change portends shifts in water demand and availability which may damage or cause intersectoral water reallocation in water short regions. This study investigates effects of climatic change on regional water demand and supply as well as the economy in the San Antonio Texas Edwards Aquifer region. This is done using a regional model which portrays both hydrological and economic activities. The overall results indicate that changes in climatic conditions reduce water resource availability and increase water demand. Specifically, a regional welfare loss of $2.2-$6.8 million per year may occur as a result of climatic change. Additionally, if springflows are to be maintained at the currently desired level to protect endangered species, pumping must be reduced by 9-20% at an additional cost of $0.5 to $2 million per year.

Dennis P. Lettenmaier, Andrew W. Wood, Richard N. Palmer, Eric F. Wood, and Eugene Z. Stakhiv. 1999. "Water Resources Implications of Global Warming: A U.S. Regional Perspective," Climatic Change, Vol. 43, No. 3, November, pp. 537-579.
ABSTRACT: The implications of global warming for the performance of six U.S. water resource systems are evaluated. The six case study sites represent a range of geographic and hydrologic, as well as institutional and social settings. Large, multi-reservoir systems (Columbia River, Missouri River, Apalachicola-Chatahoochee-Flint (ACF) Rivers), small, one or two reservoir systems (Tacoma and Boston) and medium size systems (Savannah River) are represented. The river basins range from mountainous to low relief and semi-humid to semi-arid, and the system operational purposes range from predominantly municipal to broadly multi-purpose. The studies inferred, using a chain of climate downscaling, hydrologic and water resources systems models, the sensitivity of six water resources systems to changes in precipitation, temperature and solar radiation. The climate change scenarios used in this study are based on results from transient climate change experiments performed with coupled ocean-atmosphere General Circulation Models (GCMs) for the 1995 Intergovernmental Panel on Climate Change (IPCC) assessment. An earlier doubled-CO2 scenario from one of the GCMs was also used in the evaluation. The GCM scenarios were transferred to the local level using a simple downscaling approach that scales local weather variables by fixed monthly ratios (for precipitation) and fixed monthly shifts (for temperature). For those river basins where snow plays an important role in the current climate hydrology (Tacoma, Columbia, Missouri and, to a lesser extent, Boston) changes in temperature result in important changes in seasonal streamflow hydrographs. In these systems, spring snowmelt peaks are reduced and winter flows increase, on average. Changes in precipitation are generally reflected in the annual total runoff volumes more than in the seasonal shape of the hydrographs. In the Savannah and ACF systems, where snow plays a minor hydrological role, changes in hydrological response are linked more directly to temperature and precipitation changes. Effects on system performance varied from system to system, from GCM to GCM, and for each system operating objective (such as hydropower production, municipal and industrial supply, flood control, recreation, navigation and instream flow protection). Effects were generally smaller for the transient scenarios than for the doubled CO2 scenario. In terms of streamflow, one of the transient scenarios tended to have increases at most sites, while another tended to have decreases at most sites. The third showed no general consistency over the six sites. Generally, the water resource system performance effects were determined by the hydrologic changes and the amount of buffering provided by the system's storage capacity. The effects of demand growth and other plausible future operational considerations were evaluated as well. For most sites, the effects of these non-climatic effects on future system performance would about equal or exceed the effects of climate change over system planning horizons.

Rosenberg, Norman J., Daniel J. Epstein, David Wang, et al. 1999. "Possible Impacts of Global Warming on the Hydrology of the Ogallala Aquifer Region," Climatic Change, Vol. 42, No. 4, August, pp. 677-692.
ABSTRACT: The Ogallala or High Plains aquifer provides water for about 20% of the irrigated land in the United States. About 20 km3 (16.6 million acre-feet) of water are withdrawn annually from this aquifer. In general, recharge has not compensated for withdrawals since major irrigation development began in this region in the 1940s. The mining of the Ogallala has been pictured as an analogue to climate change in that many GCMs predict a warmer and drier future for this region. In this paper we attempt to anticipate the possible impacts of climate change on the sustainability of the aquifer as a source of water for irrigation and other purposes in the region. We have applied HUMUS, the Hydrologic Unit Model of the U.S. to the Missouri and Arkansas-White-Red water resource regions that overlie the Ogallala. We have imposed three general circulation model (GISS, UKTR and BMRC) projections of future climate change on this region and simulated the changes that may be induced in water yields (runoff plus lateral flow) and ground water recharge. Each GCM was applied to HUMUS at three levels of global mean temperature (GMT) to represent increasing severity of climate change (a surrogate for time). HUMUS was also run at three levels of atmospheric CO2 concentration (hereafter denoted by [CO2]) in order to estimate the impacts of direct CO2 effects on photosynthesis and evapotranspiration. Since the UKTR and GISS GCMs project increased precipitation in the Missouri basin, water yields increase there. The BMRC GCM predicts sharply decreased precipitation and, hence, reduced water yields. Precipitation reductions are even greater in the Arkansas basin under BMRC as are the consequent water yield losses. GISS and UKTR climates lead to only moderate yield losses in the Arkansas. CO2-fertilization reverses these losses and yields increase slightly. CO2 fertilization increases recharge in the base (no climate change) case in both basins. Recharge is reduced under all three GCMs and severities of climate change.

Global Studies Regional Studies Extreme Weather CLIMATE CHANGE AND HYDROLOGIC RESOURCES - ABSTRACTS