Scarce Water Supplies Research Articles

Microcolonial fungi: survival potential of terrestrial vegetative structures.

So far mainly spores or other "differentiated-for-survival" structures were considered to be resistant against extreme environmental constraints (including extraterrestrial challenges). Microcolonial fungi (MCF) are unique growth structures formed by eukaryotic microorganisms inhabiting rock varnish surfaces in terrestrial deserts. They are here proposed as a new object for exobiological study. Sun-exposed desert rocks provide surface habitats with intense solar radiation, a scarce water supply, drastic changes in temperature, and episodic to sporadic availability of nutrients. These challenging conditions reduce the diversity of life to MCF, whose resistance to desiccation and tolerance for ultraviolet (UV) radiation make them survival specialists. Based upon our studies of MCF, we propose that the following mechanisms are universally employed for survival on rock surfaces: (1) compact tissue-like colony organization formed by thermodynamically optimal round cells embedded in extracellular polymeric substances, (2) the presence of several types of UV-absorbing compounds (melanins and mycosporines) and antioxidants (carotenoids, melanins, and mycosporines) that convey multiple stress resistance to desiccation, temperature, and irradiation changes, and (3) intracellular developmental mechanisms typical for these structures.

Water Management in Islam

In the Middle East and North Africa, water is rapidly becoming the key development issue. The region has one of the highest population growth rates in the world and scarce natural water supplies. In this region and others, policy makers have often proposed or even tried to implement policies such as higher water tariffs or privatization without considering local culture, including religion; which clearly influences how people perceive and manage a resource, such as water. In addition to supporting large minorities following various faiths, the region is home to 300 million Muslims. Therefore, developing an understanding of the Islamic perspective on proposed water management polices is a key for sustainable and equitable development for Muslim countries in the Middle East and North Africa, and elsewhere. This volume presents Islamic perspectives on a number of proposed water-management policies, including water demand management, wastewater re-use, and higher tariffs. The book opens avenues for wider dialogue amongst researchers working at identifying the most promising water management policies; adds to our knowledge of some of the influences on formal policy and informal practice; and makes these ideals available to a broader public. It serves as a concrete example of the benefit of examining development in the context of values and culture. It also dispels common misconceptions about the Islamic view on water management practices such as selling water and wastewater reuse. Water Management in Islam will interest researchers, scholars, and students in natural resource management, Islamic studies, Middle Eastern studies, development studies, and public policy. It will also be of interest to professionals, including policy makers in donor organizations, development organizations, NGOs and government departments; and agencies, both North and South, working in the area of water management.

Integrated water management in the South Pacific: policy, institutional and socio-cultural dimensions

As scarce water supplies in urban environments come under increasing pressure, water managers are forced to widen technical analyses to incorporate issues related to water governance. The concept of integrated water management has been developed to highlight that social, institutional and economic issues, in addition to technical and ecological considerations, need to be considered concurrently. In this paper, the integrated water management framework is used to highlight some of the social and institutional issues of concern to water management in the South Pacific. A case study of Suva, the rapidly growing capital of Fiji, is used to illustrate the complexity of the management issues facing Pacific Island countries. It is argued that the trend toward more systemic management of water resources is a positive one, but in the case of the Pacific Island countries much better accounts of inter-agency communication, community education, public engagement, institutional coordination, water pricing and water monitoring are needed.

Water, Human Rights, and Economic Instruments the Islamic Perspective

The countries of Middle East and North African (MENA) region have one of the highest average population growth rates in the world as well as scarce natural water supplies. This paper looks at the challenges of water management in the region by exploring various conceptual strands that have evolved in the discourses around water from an Islamic perspective. Islamic percepts allow the functioning of free and fair markets for water but governments need to intervene if the principles of equity and public interest are being contravened. Water Nepal Vol. Vol.9-10, No.1-2, 2003, pp.197-214

Muffled Price Signals: Household Water Demand under Increasing-Block Prices

In many areas of the world, including large parts of the United States, scarce water supplies are a serious resource and environmental concern. The possibility exists that water is being used at rates that exceed what would be dictated by efficiency criteria, particularly when externalities are taken into account. Because of this, much attention has been paid by policy makers and others to the use of demand management techniques, including requirements for the adoption of specific technologies and restrictions on particular uses. A natural question for economists to ask is whether price would be a more cost-effective instrument to facilitate water demand management. As a first step in such an investigation, this paper draws upon a newly-available set of detailed data to estimate econometrically the demand function for household use of urban water supplies. We analyze cross-sectional time-series data that track 1,082 single-family households served by 16 water utilities in 11 urban areas in the United States and Canada. Because of the diverse multiple-block pricing structures that abound, estimating the effects of price and price structure on residential water demand poses some challenging and interesting problems. We find that the sensitivity of residential water demand to price is quite low, and that the effect of price structure may be more influential than the magnitude of marginal price itself. The household-level data we use allow us to assess the influences on residential water demand of climate, sociodemographic factors, and characteristics of housing stock, including home vintage. Our results indicate substantial heterogeneity in likely household responses to utility demand-management policies.

A Model of Investment under Uncertainty: Modern Irrigation Technology and Emerging Markets in Water

AbstractThis article develops a stochastic dynamic model of irrigation technology adoption. It predicts that farms will not invest in modern technologies unless the expected present value of investment exceeds the cost by a potentially large hurdle rate. The article also demonstrates that, contrary to common belief, water markets can delay adoption. The introduction of a market should induce farms with abundant (scarce) water supplies to adopt earlier (later) than they would otherwise. This article was motivated by evidence that, contrary to NPV predictions, farms wait until random events such as drought drive returns significantly above costs before investing in modern irrigation technologies.

Water Scarcity and Urban Africa: An Overview of Urban–Rural Water Linkages

A first review of urban Africa's dependence on larger landscapes for water is presented. Tables document: changing water sources between 1970s and 1990s; industrial and domestic wastewater treatment and disposal; electricity generation's dependence on water. Nearby groundwater and rivers were used in the 1970s; increasingly distant sources supplied the 1990s. Domestic and industrial wastes pollute groundwater and rivers. Africa's electricity depends upon large amounts of water, as dammed rivers or for power plant operation. Preserving urban Africa's scarce water supplies requires recognition of urban–rural water cycle linkages and holistic, coordinated, and equitable regional policies and practices that support ecosystem function.

Formal and Informal Markets for Water: Institutions, Performance, and Constraints

Water markets—either formal or informal—can be an efficient method for reallocating scarce water supplies. At the same time certain constraints can raise the transaction costs of trading water. This paper reviews the conditions necessary to establish successful water markets, identifies potential problems, and offers mitigating strategies. It also uses examples of several informal and formal water markets already in operation to illustrate these problems and the solutions to them.

Reducing institutional barriers to water conservation

Significant increases in water demands, in conjunction with economic and population growth, stress already scarce water supplies in dry areas. This paper shows that the principle of confronting all water users with the opportunity cost of their actions can be applied to the design of institutions that reduce barriers to water conservation. We apply the principle to the case of temporary water transfers from agriculture to cities, in which the opportunity cost of water used for agriculture is what cities are willing to pay for the water. A significant institutional barrier that blocks temporary market transfers of water is the `use it or lose it' principle of western US water law. Legislation that removes that institutional barrier to conservation by defining short-term water trading to be a beneficial use of water can promote greater total economic benefit from scarce water, if combined with measures for protecting third parties. By removing this barrier to the free flow of information on the opportunity cost of water used in agriculture, legislation can create a market for agricultural water and reduce the cost to cities of securing needed water.

ADMINISTRATIVE, INSTITUTIONAL, AND STRUCTURAL CHARACTERISTICS OF AN ACTIVE WATER MARKET1

ABSTRACT: Voluntary water transfers through markets have been advocated by many diverse groups as a means to reallocate scarce water supplies in the semi‐arid western U.S. Although transfers of water rights have occurred almost since the creation of prior appropriation laws over a century ago, functioning water markets have been very slow to develop and are few in number. The structure, composition, administration and transactions of one of the most well established water markets, shares in the Bureau of Reclamation, Colorado‐Big Thompson project, are examined to better understand the institutional and transfer conditions that sustain an active water market. Results from a detailed study of C‐BT project records reveal that between 1970 and 1993 there were 2,698 transactions through which over one‐third of the project water changed ownership or type of use. Further analysis shows that the transactions involved many individual sellers and categories of buyers with different uses, including agricultural buyers. The transfer activity and efficiency of the C‐BT market has lead some to suggest that it be used as a model for other markets. However, because this market has fewer institutional restrictions, a well developed infrastructure and unique market conditions, it will be difficult to transfer this model to other areas without accompanying modifications in water right administration and institutions.

Equity aspects of irrigation development: Evidence from two systems in the hills of Nepal

Abstract Equity is of great relevance to developing irrigation. Its two dimensions —horizontal in regard to water distribution to farmland and vertical in terms of productivity differences between farm categories — are studied in two irrigation systems, an old farmer‐managed and a new government‐agency‐managed system. Equity in the distribution of irrigation water differed between abundant and scarce water supply conditions. Paddy grown during the monsoon season when water is available in abundant quantity shows that there was a reasonable degree of fairness in its distribution between head and tail reach farmland. However, wheat grown in the dry season with limited supply of water rendered evidence of unfair distribution demanding better management of irrigation water. The analysis of vertical equity shows that small farms are more efficient than large ones in increasing productivity through the use of irrigation facilities.

Redesigning the American lawn: a search for environmental harmony

Americans love their lawns with a passion rarely seen in other countries; fifty-eight million Americans enthusiastically plant, weed, water, spray, and mow an estimated twenty million acres of lawn. But is our dedication to these lawns contributing to the serious environmental problems facing the planet? The authors in this book state that the lawn may be an ecological anachronism, and they argue that we must rethink the way we care for our lawns so that these small pieces of the environment will demonstrate our commitment to a more ecologically sound world. The authors outline the origins of ideas about the lawn and the reasons for its enduring popularity. They describe the development of ideas about its form and the making of the lawn into an object of beauty. They explain how the lawn industry has encouraged the spread of the industrial lawn to sustain high sales of mowers, seeds, fertilizers, pesticides, and irrigation equipment. However, say the authors, Industrial Lawns can have high environmental costs: for example, power motors contribute to regional air pollution and global warming; excess fertilizers and pesticides wash off our lawns and run into our wells, streams, and lakes; grass clippings that are bagged and hauled away are major contributors to solid waste problems; and the watering of lawns depletes scarce water supplies. How can we create environmentally sound lawns? The authors offer a variety of ideas - such as moderation in our use of lawn supplements, ecological use of grass varieties, the substitution of hand mowers for power motors, and the use of grass clippings to fertilize the lawn. These strategies can help us to care for conventional lawns in ways lessdangerous to the environment. They also propose two more radical alternatives: Freedom Lawns that allow natural and unrestricted growth of grasses, clover, wildflowers, and other broad-leafed herbaceous plants; and total replacement of the lawn with new landscape designs. By choosing

A new competitor for the West's scarce water

Environmental factors have become key considerations in the scramble for scarce water supplies in the western U.S., alongside traditional users such as agriculture, municipalities, and industry. “In the last few years, the environmental demand for water for wildlife maintenance, fisheries, and water quality has been strengthened by a series of court rulings, legal interpretations, and societal pressure reflecting a renewed commitment to environmental quality,” according to David Brookshire, economist at the University of New Mexico in Albuquerque.

Population pressure on coral atolls: trends and approaching limits.

Trends and approaching limits of population pressure on coral atolls is discussed by examining the atoll environment in terms of the physical geography, the production systems, and resource distribution. Atoll populations are grouped as dependent and independent, and demographic trends in population growth, migraiton, urbanization, and political dependency are reviewed. Examination of the carrying capacity includes a dynamic model, the influences of the West, and philopsophical considerations. The carrying capacity is the "maximal population supportable in a given area". Traditional models are criticized because of a lack in accounting for external linkages. The proposed model is dynamic and considers perceived needs and overseas linkages. It also explains regional disparities in population distribution, and provides a continuing model for population movement from outer islands to district centers and mainland areas. Because of increased expectations and perceived needs, there is a lower carrying capacity for outlying areas, and expanded capacity in district centers. This leads to urbanization, emigration, and carrying capacity overshot in regional and mainland areas. Policy intervention is necessary at the regional and island community level. Atolls, which are islands surrounding deep lagoons, exist in archipelagoes across the oceans, and are rich in aquatic life. The balance in this small land area with a vulnerable ecosystem may be easily disturbed by scarce water supplies, barren soils, rising sea levels in the future, hurricanes, and tsunamis. Traditionally, fisheries and horticulture (pit-taro, coconuts, and breadfruit) have sustained populations, but modern influences such as blasting, reef mining, new industrial technologies, population pressure, and urbanization threaten the balance. Population pressure, which has lead to pollution, epidemics, malnutrition, crime, social disintegration, and foreign dependence, is evidenced in the areas of Tuvalu, Kiribati, the Marshall Islands, and the Maldive Islands, independent islands. Other areas with low migration, low growth rates, and minimal urbanization include the Tokelau Islands, the Northern Cook Islands, the Tuamotu Archipelago, and the outer islands in the Federated States of Micronesia. Additional research is needed to identify and develop drought resistant and salt resistent varieties of trees, root crops, and other resources. Fresh water areas need protection from overland latrines and irrigation projects, and construction projects. Improvements are needed for regional cooperation and collaboration in industrial development. Tourism and the export industries yield income but produce urban problems. Addressing low growth areas with economic means alleviates spillover effects.

Stomatal Conductance and Photosynthesis in a Mature Scots Pine Forest. III. Variation in Canopy Conductance and Canopy Photosynthesis

(1) Water loss from coniferous plantations may lead to water shortages in regions of scarce water supply. To model growth and transpiration from a forest canopy over a year or more, it is necessary to know how conductance and photosynthesis of the entire canopy changes with season and weather. (2) The stomatal conductance and photosynthesis of current-year shoots of Scots pine (Pinus sylvestris) growing in eastern England were measured at different levels in the canopy throughout a year. Canopy conductance and canopy photosynthesis were calculated for the hours of measurement. (3) The diurnal behaviour of canopy conductance and canopy photosynthesis was substantially the same as that of the shoots. Maximum values of canopy conductance (1.6 cm s-1) occurred in September and minimum values after mid-day in July and August. Maximum rates of canopy photosynthesis (>1.2 mg m-2 s-1) occurred in October. (4) The major determinant of canopy conductance during the growing season was water vapour saturation deficit, except during periods when air temperature was less than 10 OC or incident quantum flux density was low, particularly at dawn and dusk. Canopy conductance declined sensitively with saturation deficit between 0.5 and 15 kPa but then remained constant at larger deficits. Stomatal closure at large saturation deficits had a major influence on canopy conductance in July and August, in spite of an increasing leaf area index as the new shoots elongated during this period. (5) Rate of canopy photosynthesis was strongly dependent on the quantum flux density except at high temperatures and large saturation deficits when canopy photosynthesis was also limited by canopy conductance. The response of canopy photosynthesis to light incident above the canopy was linear except at both high light and large saturation deficits when hysteresis occurred. (6) The relationship between canopy photosynthesis and canopy conductance was curvilinear at large saturation deficits but independent of conductance at small deficits.

The Causes and Consequences of Synchronous Flushing in a Dry Tropical Forest

The seasonal pattern of leaf production and fate of leaf cohorts were assessed in 59 species of woody plants over a period of 28 months in a West African dry forest (mean annual rainfall 1100 mm). In all species, leaves were produced in synchronous flushes. Flushing patterns varied somewhat between species and between individuals within species, although all flushing activity was restricted to wet periods. Damage to leaves by folivorous insects was largely confined to newly flushed leaves. Insects inflicted severe damage to 13 percent of new leaf cohorts. Species having potential deterrents to folivore attack (hairy leaves or secondary compounds) were attacked less frequently than species without apparent protection. Prolonged flushing activity brought about an added risk of insect attack in species lacking such protection. Drought is considered to be the most important single factor affecting the growth, distribution, and phenology of woody species in this dry forest. The restriction of leaf production to short, synchronous flushing periods is adequately explained in terms of physiological constraints relating to the avoidance of moisture stress. A consequence of this rapid flushing, however, may be escape from folivory. FLUSHING, OR THE SYNCHRONOUS PRODUCTION OF A NEW LEAF CROP, is characteristic of both temperate and tropical woody species (Richards 1952, Kramer and Kozlowski 1979). The pattern of leaf production in individual shoots, plants, and populations is generally periodic in the tropics (Alvim 1964, Longman and Jenik 1974, Leigh and Smythe 1978, Reich and Borchert 1982), but it is only in seasonally dry tropical environments that large numbers of shoots, individuals, and species flush in synchrony (Njoku 1963, Hopkins 1970, Daubenmire 1972, Frankie et al. 1974, Borchert 1980, Lieberman 1982, Reich and Borchert 1982, 1984). Rapid, synchronous flushing may be viewed as an adaptation to exploit scarce and intermittent water supplies and to avoid producing young, uncutinized foliage when the danger of desiccation is great. Young leaves are particularly vulnerable to folivore attack due to their lack of mechanical protection and their high nutrient and water content (Feeny 1970, Rockwood 1974, Scriber and Slansky 1981). McKey (1974) and Feeny (1976) suggest that the production of leaves in rapid, synchronous flushes may contribute to escape from folivory. They hypothesize that flushing occurs when folivores are at low density or are inactive, and that the majority of new leaves may therefore have the opportunity to mature and harden prior to an increase in the folivore population. Water conservation and escape from folivory are suggested explanations for the phenomenon of rapid synchronous flushing, but no study has been reported in which both possibilities are considered. In this paper we describe patterns of flushing phenology and folivory in a dry tropical forest in Ghana. In the context of flushing, we examine the incidence of folivory in relation to plant chemical and morphological traits, and ask whether rapid, synchronous production of leaves provides a significant means of folivore escape. We also evaluate the relative importance of folivory and drought in the evolution of leaf flushing patterns in species of this dry tropical forest.

IMPACT ON GROUNDWATER RESOURCES OF CONVERSION FROM FURROW TO DRIP IRRIGATION1

ABSTRACT A model is developed to analyze the groundwater conservation and depletion effects of converting sugarcane irrigation from the furrow to the drip method. The results do not support the commonly held notion that more efficient use of irrigation water will release scarce water supplies for metropolitan growth.

ESTIMATING THE VALUE OF WATER AMONG REGIONAL ECONOMIC SECTORS USING THE 1972 NATIONAL INTERINDUSTRY FORMAT1

ABSTRACT: Recent growth in irrigated agriculture and metropolitan areas of the Western United States suggests that if growth continues, there will be a potential shortage in future water resources. Compound the expansion of agriculture and municipal demands with possible enaction of instream flow requirements, a method to allocate water among alternative economic sectors in the West is needed. In this study, an interindustry‐linear programming model based on the 1972 national model format is used to allocate scarce water supplies among competing regional economic sectors. The shadow price of water and the sectorial value of water at different availabilities for each competing sector is derived. Also, economic sectors are ranked by value of water at different water availabilities.

OPTIMIZATION OF WATER RESOURCES FOR IRRIGATION IN EAST JORDAN1

ABSTRACTThe paper describes an approach towards optimal allocation of surface and ground water resources to three agricultural areas in the Jordan Valley under conditions of scarce water supply. The optimizing model allocates water from three main rivers, each with reservoir storage, and from two ground water sources to three irrigation regions. Productivity of irrigation water, expressed as the net present value of the regional agricultural output, but allowing for crop water deficits, is first maximized using nonlinear programming. The allocation process then adopts techniques of linear programming to determine the least cost alternative based on the unit cost of water from each resource at each destination, as it varies with time.