Showing papers on "Water supply published in 1998"

World water demand and supply, 1990 to 2025: scenarios and issues

Abstract: Presents two alternative scenarios of water demand and supply for 118 countries over the 1990 to 2025 period and develops indicators of water scarcity for each country and for the world as a whole. This study is the first step in IWMI's long-term research goal: to determine the extent and depth of water scarcity, its consequences for individual countries and what can be done about it.

The world's water : the biennial report on freshwater resources

Abstract: Produced biennially, "The World's Water" is the most comprehensive and up-to-date source of information and analysis on freshwater resources. Each new volume examines critical global trends and offers the best data available on a variety of topics related to water. The 2011-2012 edition features chapters on water policy, transboundary waters, and the effects of fossil fuel production on water resources, among other timely issues. Water briefs provide concise updates on topics including bottled water, The Great Lakes Water Agreement, and the state of the Colorado River. "The World's Water" is coauthored by MacArthur 'genius' Peter H. Gleick and his colleagues at the world-renowned Pacific Institute. Since the first volume was published in 1998, the series has become an indispensable resource for professionals in government and nongovernmental organisations, researchers, students, and anyone concerned with water and its use.

China's water shortage could shake world food security.

Abstract: This report indicates the global concern about Chinas water shortages and describes basin supplies global availability of grain and reasons for water losses. There is little precise data on how land productivity will be affected by declines in irrigation. Reports from the "China Daily" indicate that the 1995 grain harvest in Shandong province declined by 2.7 million tons (food for 9 million people) due to water failures of the Yellow River. A delegate at the 1998 National Peoples Congress pointed out that rural villages nationwide had shortages of 30 billion cu. m and losses of 20 million tons of grain production. About 70% of grain harvests rely on irrigation. Water demand for residential use and industrial use is likely to increase and compete with farm use. One unlikely option is to divert irrigation water to cities as needed and import grain. The entire agricultural energy and industrial economies need to be made more water efficient. Agriculture will need to produce more water efficient crops and livestock products and less water intensive energy supplies. Another alternative is to divert water from one location to another. Water pricing could reinforce efficiency of use. Use of composting toilets could reduce human residential water demand. Urban capacity building should rely on separate industrial and residential wastewater systems. Investing in technologies for industry can reduce water demand among paper and steel producers. The fastest growing grain market is in North Africa and the Middle East. Trends in principal grain exporting countries with 85% of global exports indicate no growth in grain production for export since 1980.

Water distribution system and diarrheal disease transmission: a case study in uzbekistan

Abstract: Deteriorating water treatment facilities and distribution systems pose a significant public health threat, particularly in republics of the former Soviet Union. Interventions to decrease the disease burden associated with these water systems range from upgrading distribution networks to installing reverse osmosis technology. To provide insight into this decision process, we conducted a randomized intervention study to provide epidemiologic data for water policy decisions in Nukus, Uzbekistan, where drinking water quality is suboptimal. We interviewed residents of 240 households, 120 with and 120 without access to municipal piped water. Residents of 62 households without piped water were trained to chlorinate their drinking water at home in a narrow-necked water container with a spout. All study subjects (1583 individuals) were monitored biweekly for self-reported diarrheal illness over a period of 9.5 weeks. The home chlorination intervention group had the lowest diarrheal rate (28.8/1,000 subjects/month) despite lack of access to piped water in their homes. Compared with the two groups that did not receive the intervention this rate was one-sixth that of the group with no piped water (179.2/1,000 subjects/month) and one-third that of the households with piped water (75.5/1,000 subjects/month). More than 30% of the households with piped water lacked detectable levels of chlorine residues in their drinking water, despite two-stage chlorination of the source water, and were at increased risk of diarrhea. Forty-two percent of these municipal users reported that water pressure had been intermittent within the previous two days. The dramatic reduction in diarrheal rates in the home-chlorination intervention group indicates that a large proportion of diarrheal diseases in Nukus are water-borne. The home-chlorination group had less diarrhea than the group with piped water, implicating the distribution system as a source of disease transmission. Taken together, these epidemiologic data would support the hypothesis that diarrhea in the piped water group could be attributed to cross-contamination between the municipal water supply and sewer, due to leaky pipes and lack of water pressure. Relatively inexpensive steps, including chlorination, maintaining water pressure, and properly maintaining the distribution system, rather than reverse osmosis technology, should reduce diarrheal rates.

A Review on Monthly Water Balance Models for Water Resources Investigations

Abstract: Research on the development and application of monthly water balance models has been carried out since the 1940s. A good body of experience has been gained for many models, and a review of these models is needed. Beginning with the development of monthly water balance models from the earliest times, this paper discusses the relevance of various aspects of the practical application of such models. Monthly water balance models were introduced originally to evaluate the importance of different hydrologic parameters under a variety of hydrologic conditions. Present applications of water balance models are directed along three main lines: reconstruction of the hydrology of catchments, assessment of climatic impact changes, and evaluation of the seasonal and geographical patterns of water supply and irrigation demand.

Ecosystem services, efficiency, sustainability and equity: South Africa's Working for Water programme.

Abstract: Placing a value on ecosystem services is essential for making rational choices about competing forms of land use. In developing countries, where short-term economic growth and social delivery take precedence over conservation, placing a monetary value on ecosystem services is the only way of ensuring intervention [1xAlylward, B.A. and Barbier, E.B. Biodiv. Conserv. 1992; 1: 34–50Crossref | Scopus (41)See all References][1]. The challenge is to ensure that these interventions incorporate ecological sustainability and fairness, as well as efficiency. There are few such projects in the world, especially among the poorer nations in the developing `south'. One example is South Africa's Working for Water programme, which maximizes an ecosystem service (the delivery of water), enhances sustainability by eliminating invading alien plants, and promotes social equity through jobs and training for economically marginalized people.In South Africa, the introduction of hundreds of species of alien trees has led to many populations of aggressive invaders, which convert species-rich vegetation to single-species stands of trees, increasing biomass and decreasing streamflow dramatically [2xvan Wilgen, B.W. et al. S. Afr. J. Sci. 1997; 93: 404–411See all References][2]. In response to a concern that commercial afforestation with alien trees would impact on water resources, a series of whole-catchment experiments was established in the Western Cape in 1936 and in other high-rainfall areas in the 1950s. The results were later used to illustrate the potential impact that invasions (as opposed to formal commercial forestry) could have on water, given that such invasions were comparable to afforestation [3xLe Maitre, D.C. et al. J. Appl. Ecol. 1996; 33: 161–172CrossrefSee all References][3].Although alien plant clearing programmes were initiated in the early 1970s, they later fell behind when funding declined in the face of other demands. However, when the cost of clearing was compared with that of developing additional water supply schemes [2xvan Wilgen, B.W. et al. S. Afr. J. Sci. 1997; 93: 404–411See all References][2], it was shown that such clearing was cost-effective—more water could be delivered at a lower cost when control operations were in place than if they were not. The sooner such operations were initiated the better, because alien plant spread resulted in exponential increases in clearing costs over time. Cost–benefit analysis had demonstrated that the removal of alien plants maximized the utility of an ecosystem service and was, therefore, an economically efficient intervention.The studies were completed when South Africa had elected its first democratic government, and local scientists made a conscious decision to communicate these results to the Minister of Water Affairs (Kader Asmal) in July 1995. They stressed economic efficiency, the advantages for ecosystem stability and biodiversity conservation, and the opportunities for job creation. Asmal's response was immediate; he could see that the cost-effective delivery of a crucial ecosystem service could be sustainably linked to socioeconomic development and biodiversity storage. A programme, dubbed Working for Water to capture the essence of job creation to secure an environmental goal, was launched with an initial budget of $US five million. In its two-year existence, the programme has grown rapidly. Annual funding by the government rose to $US 50 million by November 1997, with additional inputs from the private sector and foreign aid. The impact of the programme on job creation played a large part in securing funding. The initial grant created over 7000 jobs for previously unemployed people in the labour-intensive clearing projects, reaching over 35 000 jobs in March 1998.A group of scientists from the CSIR Division of Water, Environment and Forestry Technology mapped the extent of invasion of all important species on 1:250 000 scale maps, using local experts' knowledge. These data were used to estimate potential water use and costs of clearing. The current invasion covers the equivalent of 1.7 million ha, and is estimated to be using 3300 million m3 of water (almost 7% of the runoff of the country). This is more than the estimate for the forest industry, which is subject to stringent controls to reduce its impact on water resources. About 15 species (including Australian Acacia, Eucalyptus and Hakea species, and European and American Pinus and Prosopis species) were responsible for 90% of the problem. The cost to clear the invasions would be around $US two billion, or roughly $US 100 million per year for the estimated 20 years that it would take to deal with the problem. However, this could be reduced in a number of ways. First, some species do not have a large impact on water resources. Acacia cyclops, an Australian tree that invades coastal dune areas, covers 300 000 ha but, by virtue of its coastal distribution away from upper watershed areas, it could be excluded from a programme aimed at securing water resources. Second, biological control (using species-specific insects and pathogens from the invader's country of origin) offers hope for reducing clearing costs. By ignoring nonwater users and introducing biological control, clearing costs could be reduced to $US 800 million (or $US 40 million per year), a far more manageable target.Nonetheless, the programme faces significant challenges. These include uncertainties in the models used to estimate water use, especially where these have implications for the forest industry, which in essence farms with invasive trees and will have to avoid penalties for water use as a result of alien plant spread. The industry will also need to absorb the impacts of biological control agents should they be released and will thus remain very critical. Proponents that promote the establishment of forests to offset global CO2 increases have fundamental problems with programmes that remove trees and thus biomass; however, the potential for carbon sequestration in this way in South Africa is small, whereas the potential for biodiversity loss is large.There is little doubt that the monetary valuation of an ecosystem service, formalized in a cost–benefit analysis, was the major stimulus for the launch of the Working for Water programme. Cutting down water-demanding alien trees is a more efficient way of delivering water than building new dams, a fact that was readily appreciated by politicians operating in a cash-strapped economy. Of equal importance are the sustainable delivery of an ecosystem service, the restoration and conservation of biodiversity, and the contribution towards improving the quality of life amongst previously disadvantaged people. This is a promising start to probably the largest ecosystem management programme in Africa, and it demonstrates the potential value of placing a monetary estimate, initially at least, on an ecosystem service.

Solutions for a water-short world.

Abstract: The freshwater shortage is emerging as one of the most critical global natural resource issues. At present 31 countries face chronic freshwater shortages and this figure is expected to rise to 48 countries (encompassing 35% of the worlds projected population) by the year 2025. Population growth rising demands for water for irrigated agriculture and industrial development massive urbanization and rising living standards are contributing to the shortage. Pollution has produced a decrease in the finite supply of freshwater at the same time that annual global water withdrawals are increasing at an average rate of 2.5-3.0% each year. The combination of polluted water improper waste disposal and poor water management has been associated with serious public health problems including malaria cholera typhoid and schistosomiasis. Prevention of a crisis requires strategies aimed at managing both the supply and the demand for freshwater. Expansion of family planning programs in developing countries represents an essential measure for ensuring that population growth slows to sustainable levels in relation to the freshwater supply. Just as the Green Revolution transformed agriculture in the 1960s a Blue Revolution is required now to conserve and manage freshwater supplies. Uncoordinated water management policies by separate jurisdictions must be replaced at the national level with a watershed or river basin management perspective. At the international level countries that share river basins can devise policies to manage water resources more equitably. Development agencies need to place more emphasis on assuring the supply and management of freshwater resources and on providing sanitation as part of development and public health programs.

Groundwater in Urban Development: Assessing Management Needs and Formulating Policy Strategies

Abstract: People have clustered at the water's edge throughout civilization for the most fundamental of reasons: without water there is no life. Every major city in the world has a body of water or aquifer nearby, since rivers and lakes predetermined where people would gather and dwell, groundwater constitutes about 98 percent of the fresh water on our planet (excepting that captured in the polar ice caps). This makes it fundamentally important to human life and to all economic activity. Groundwater resources in and around the urban centers of the developing world are exceptionally important as a source of relatively low-cost and generally high-quality municipal and domestic water supply. At the same time, the subsurface has come to serve as the receptor for much urban and industrial wastewater and for solid waste disposal. There are increasingly widespread indications of degradation in the quality and quantity of groundwater, serious or incipient, caused by excessive exploitation and/or inadequate pollution control. The scale and degree of degradation varies significantly with the susceptibility of local aquifers to exploitation-related deterioration and their vulnerability to pollution. Management strategies need to recognize and to address the complex linkages that exist between groundwater supplies, urban land use, and effluent disposal. Groundwater tables have become the focus of keen interest in recent years, as the supplies of water underlying urban areas have dwindled and deteriorated, threatening the millions of people who live above. When conditions are right, aquifers refill regularly from infiltrating rainfall and runoff, although sometimes with a substantial time lag. But those favorable conditions are severely altered when the ground above is overbuilt.

Gender in Water Resources Management, Water Supply and Sanitation: Roles and Realities Revisited

Abstract: This book investigates how gender is present in the newly emerging principles on the sustainable management of water resources. The book also reviews how these genderspecified principles are currently applied in the water supply, sanitation and hygiene sector. Operationalization has developed farthest in new drinking water supply services. Participation of women alongside men in planning, design, maintenance and management has brought distinct benefits to the functioning and use of the systems and created more equal chances for training and functions of women and men. Yet a true gender balance, in which benefits, burdens and control are shared equitably for optimal service sustainability and development results remains to be achieved. In comparison, sanitation development and management lag behind. Yet improved sanitation has tremendous benefits in that it prevents the contamination of water and soil and improves public health. A gender approach in sanitation recognizes and responds to male-female differences in demand, work and opportunities in the different population strata. It helps redress the sanitation imbalance and offers new chances for men and women to jointly manage their own environment and programmes. While women have initially been bypassed in modern water and sanitation management, men have been neglected in hygiene improvements. In a gender approach in hygiene education the division of work, resources and decision-making between men and women is investigated and each sex is addressed on their own areas of authority, skills and responsibility. This prevents that additional and unpaid hygiene work goes only to women and girls and responsibilitilies of men for work, resource provision and own behaviour chance are overlooked. The use of a simple gender analysis instrument, which is described in the book’s first chapter, has helped in analysing the above developments and is recommended for maintreaming gender as part of programme planning, appraisal and monitoring and evaluation.

Domestic water supply using rainwater harvesting

Abstract: World-wide pressure on water resources is mounting as populations grow, consumption per capita increases, ‘fossil’ water resources are mined and the climate changes. Domestic water usage is a significant component of water demand. Under favourable circumstances, it can be met in part or in whole by rainwater collected close to an individual dwelling. Interest in such systems is growing especially in rural areas where either rainfall is well distributed through the year, or where surface water is absent, ground water mineralized and centralized piped supplies unaffordable. Roof water collection is also being practised on low-rise and high-rise buildings in some cities having wet climates. The principles and components of rainwater harvesting are reviewed. Factors leading to the growing use of domestic rainwater harvesting in three different developing countries (North China, East Africa and Singapore) as case studies are discussed along with current practices, design options for system components and consi...

Long-term planning methodology for water distribution system rehabilitation

Abstract: The most expensive component of a water supply system is the distribution network. Deterioration due to aging and stress causes increased operation and maintenance costs, water losses, reduction in the quality of service, and reduction in the quality of water supplied. In this paper an approach is proposed in which the water distribution network economics and hydraulic capacity are analyzed simultaneously over a predefined analysis period while the deterioration over time of both the structural integrity and the hydraulic capacity of every pipe in the system is explicitly considered. The cost associated with each pipe in the network is calculated as the present value of an infinite stream of costs. In Kleiner et al. [this issue] a methodology is presented to implement this approach into a decision support system that facilitates the identification of an optimal rehabilitation strategy.

Implementing a Demand-Driven Approach to Community Water Supply Planning: A Case Study of Lugazi, Uganda

Abstract: A new water supply and sanitation planning approach is now becoming accepted in many developing countries. This new approach holds that investment in the water and sanitation sector should be”demand driven,” i.e., that households should be provided with services they want and for which they are willing to pay. This paper shows how results from a rapid appraisal of household demand for improved water services were used to identify the appropriate water service level in Lugazi, Uganda. The authors argue that a demand-driven planning process requires flexibility on the part of engineering consultants, planners, and government officials to respond to the kind of unexpected findings that are likely to emerge from serious dialogue with project beneficiaries. Engineering consultants, government planners, and donors must be willing to tackle water supply problems with an open mind and to create different water scenarios for a community as a function of the community's own desires. At present, however, re...

Learning what works : a 20 year retrospective view on international water and sanitation cooperation

Abstract: This year marks the twentieth year of the UNDP-World Bank Water and Sanitation Program. The author traces the developments in the water and sanitation sector since the program's inception in 1978, and analyzes how the program has affected by these developments. The case study represents an attempt to describe in parallel the evolution of the program and the evolution of international thinking concerning water and sanitation during the 20 years of the program's existence.

Performance Risk Analysis for Fukuoka Water Supply System

Abstract: In this study, simulation is used to evaluate the performance of the municipal water system in Fukuoka city. In combination with daily simulation model, a kind of risk model incorporating water demand prediction is presented. This model applies five risk indices: reliability, resiliency, vulnerability, drought risk index (DRI) and drought damage index (DDI). They aid in the identification of operation policies for the municipal water system, and the planning and operational policies obtained are aimed at achieving minimum risk for a given scenario of operation. In this paper, the performance risk of the municipal water system is investigated under three alternatives: (1) the existing system operation when available supply from the Chikugo river is decreased; (2) water restrictions for different percentages of reduction are implemented; and (3) available water supply increases when desalination of sea water is implemented. The results obtained show that savings of between 5 and 12% of water consumption from May 1, or increasing of daily desalination of sea water about 30 000 m3 or more, may efficiently decrease the performance risk of the Fukuoka water supply system. Potentials also exist for further increase of reservoir storage by more rational operation. The measure that more attention should be paid to increasing the water supply from stable sources is recommended as well.

A large outbreak of cryptosporidiosis associated with a public water supply from a deep chalk borehole

Abstract: Summary: Three hundred and forty-five confirmed cases were reported in a large waterborne outbreak of cryptosporidiosis in North Thames in the spring of 1997. The descriptive epidemiology, attack rates, a case control study, and the detection of oocysts in the water suggested strongly that the outbreak was associated with drinking unboiled tap water that originated from one deep chalk borehole. The 746 000 people living in the water distribution area were advised to boil their drinking water. Investigations did not reveal how oocysts entered the borehole. This is the first published report of a cryptosporidium outbreak caused by filtered borehole water and we believe it to be the largest outbreak due to groundwater to have been reported. Borehole supplies are regarded as relatively pure sources of water and this outbreak has implications for the future monitoring and treatment of drinking water extracted from boreholes. Commun Dis Public Health 1998; 1: 239-43.

Water-Resources Optimization Model for Santa Barbara, California

Abstract: A simulation-optimization model has been developed for the optimal management of the city of Santa Barbara's water resources during a drought. The model, which links ground-water simulation with linear programming, has a planning horizon of 5 years. The objective is to minimize the cost of water supply subject to: water demand constraints, hydraulic head constraints to control seawater intrusion, and water capacity constraints. The decision variables are monthly water deliveries from surface water and ground water. The state variables are hydraulic heads. The drought of 1947–51 is the city's worst drought on record, and simulated surface-water supplies for this period were used as a basis for testing optimal management of current water resources under drought conditions. The simulation-optimization model was applied using three reservoir operation rules. In addition, the model's sensitivity to demand, carryover [the storage of water in one year for use in a later year(s)], head constraints, and capacity c...

Development of a Preliminary Ground Water Flow Model for Water Resources Management in the Pingtung Plain, Taiwan

Abstract: Pingtung Plain is formed by Quaternary alluvial fan material from the three main rivers: Kaoping, Tungkang and Linpien. Ground water is the major water supply source on the plain. This is principally extracted from two aquifers. The natural ground water source is derived mainly from direct rainfall percolation and infiltration from the three rivers, with their catchments lying partly outside the plain. Rainfall characteristics are therefore the main factors controlling water resources availability. Pingtung Plain is an important primary production area for southern Taiwan, the comparatively warm climate allowing a long growing season, diversified cropping and the rearing of aquacultural produces. Approximately 75 percent of irrigation and domestic water supplies are derived from ground water. A water balance for the entire plain indicates that ground water resources, under optimized management, are sufficient to meet the existing multi-purpose uses. Development of a hydrogeological conceptual model is the first phase of a numerical ground water flow simulation. Preliminary results are encouraging, with the final simulations affording better insight to the hydraulic behavior of the aquifer system. Data input requirements for model operation fall into three categories: hydrological stresses, hydrogeological parameters and boundary conditions. After the model is built, the normal numerical modeling process requires significant calibration and sensitivity analyses for the hydrogeological parameters and stresses which are the most sensitive, but the least well defined. A well-calibrated simulation model can lead to a reliable and realistic management model. With this in mind, the calibration processes detailed are presented, and these data are introduced as initial values in the calibration process.

Water insecurity and the poor: Issues and research needs

Abstract: Household water insecurity is a pressing problem in developing countries. Unsustainable water withdrawal is increasing due to population growth, industrialization, urbanization, and increasing agricultural production which leads to various problems. The number of countries facing problems of water scarcity and insufficient water supply is rising. Already there are 1.2 billion people without access to clean water, many of whom live in 20 developing countries classified as ‘water scarce’. Typically it is found in these countries, that the poor pay particularly high prices for water and are most water insecure. Progress towards water security can be made only if there is a more comprehensive understanding of the interactions among waters’ various characteristics and functions. Water is not only a natural resource, but also an economic commodity, and a human consumption good or entitlement. The problems of water insecurity can be grouped under three main headings: availability, access and usage. In the framework of a multidisciplinary approach to the analysis of water problems, the paper elaborates on these three elements, defining sectoral and cross-sectoral knowledge gaps. The paper concludes with a research agenda in support of improved policy design and action.

Susceptibility of Water Supply Reservoirs to Drought Conditions

Abstract: The knowledge of the behavior of a water supply system during hydrological drought events is useful to assess the risk of shortages and to undertake the necessary actions to reduce drought impacts. In the present paper relationships between performance indices of a water supply reservoir and severity of hydrological droughts identified using the concepts of runs have been studied. A linear relationship between water shortage index and mean intensity (or cumulative deficit) of droughts of the same length was derived analytically and verified by simulation. Simulation has been carried out during drought periods for two demand patterns by using either standard operating policy (SOP) or different hedging policies. Plots of performance indices versus drought characteristics show in some cases a definite pattern whereas in others the points present a relatively high scatter. When a hedging operating policy is applied, though the scatter of the points increases, some relationships still preserve a definite patte...

Deregulated Private Water Supply: A Policy Option for Developing Countries

Abstract: Many citizens in developing and transition economies are excluded from enjoying safe and reliable water supply In many cities, 30 to 60 percent of the population has no formal water hook-up at all, but rather must resort to wells, buckets, supply by tanker-trucks, and physical transport of water through human labor and beasts of burden A few simple facts illustrate the serious nature of this problem In Jakarta, 75 percent of the population has no formal connection; in Maputo 65 percent In Madras, the percentage served is around 50 percent; and even in relatively prosperous Manila, 29 percent of the citizenry has no connection When individuals must resort to nonpiped water sources, prices are often at least 10 to 20 times higher In Luanda, where the price for piped supply is around nine cents per cubic meter, households can pay as much as $1600 per cubic meter for tanker supply Table 1 portrays some connection rates and price differentials The fundamental problem is institutional rather than technological Tariffs set by governments at levels below cost recovery fail to encourage inclusion In developing countries, water utilities recover on average around 30 percent of their total costs (World Bank 1994) As a

Water as an economic good

Abstract: There has been much debate in recent years about whether or not water should be regarded as an ‘economic good’, and, if so, what this implies. This paper discusses both water resources in general and the more specific issue of domestic water supply within the context of current debates on sustainable development. It addresses some practical and some more philosophical aspects of the matter, and how these relate to the concerns of different international organisations involved in the sector. It argues that water should be regarded as an economic good, but in a broad rather than a narrow, ‘economistic’ sense.

Water Quality Requirements

Abstract: Successful aquaculture depends on providing animals with a satisfactory environment in which to grow. Good initial conditions for aquaculture can be assured by selecting a site with suitable soils and a high-quality water supply. An adequate environment must then be maintained over the culture period so that animals will survive and grow rapidly. Important aspects of pond soil quality have been reviewed by Boyd (1995a). In this chapter, we summarize the principal water quality requirements for pond aquaculture.

Managing the nation's water in a changing climate

Abstract: Among the many concerns associated with global climate change, the potential effects on water resources are frequently cited as the most worrisome. In contrast, those who manage water resources do not rate climatic change among their top planning and operational concerns. The difference in these views can be associated with how water managers operate their systems and the types of stresses, and the operative time horizons, that affect the Nation's water resources infrastructure. Climate, or more precisely weather, is an important variable in the management of water resources at daily to monthly time scales because water resources systems generally are operated on a daily basis. At decadal to centennial time scales, though, climate is much less important because (1) forecasts, particularly of regional precipitation, are extremely uncertain over such time periods, and (2) the magnitude of effects due to changes in climate on water resources is small relative to changes in other variables such as population, technology, economics, and environmental regulation. Thus, water management agencies find it difficult to justify changing design features or operating rules on the basis of simulated climatic change at the present time, especially given that reservoir-design criteria incorporate considerable buffering capacity for extreme meteorological and hydro-logical events.

Spatial integration of urban water services and economies of scale

Abstract: This research attempts to analyze economic effects of spatial integration of urban water service markets in Korea, employing the notion of economies of scale in terms of cost-effectiveness. The economies of scale are measured by the elasticity of supply with respect to the production cost from the translog cost function of urban water supply enterprises. It was found that the economies of scale in most urban water utility firms of Seoul Metropolitan region have continuously increased during the period 1989–1994. While the economies of scale would be hardly influenced by the changes in population density, they would tend to decrease marginally in response to the rise in employment density. If the urban water markets of the Seoul Metropolitan Region were consolidated into a single water service market without any changes to the current spatial network of water supply and regional economic attributes, the production cost would be reduced up to 47.1 percent of the actual cost in 1994. Those savings would be enough to make up for the financial deficit of the water production of the Seoul Metropolitan Region.