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Article

Water Security  

Claudia Sadoff, David Grey, and Edoardo Borgomeo

Water security has emerged in the 21st century as a powerful construct to frame the water objectives and goals of human society and to support and guide local to global water policy and management. Water security can be described as the fundamental societal goal of water policy and management. This article reviews the concept of water security, explaining the differences between water security and other approaches used to conceptualize the water-related challenges facing society and ecosystems and describing some of the actions needed to achieve water security. Achieving water security requires addressing two fundamental challenges at all scales: enhancing water’s productive contributions to human and ecosystems’ well-being, livelihoods and development, and minimizing water’s destructive impacts on societies, economies, and ecosystems resulting, for example, from too much (flood), too little (drought) or poor quality (polluted) water.

Article

International Water Law and Its Developing Role in Conflict and Cooperation Over Transboundary Water Resources  

Susanne Schmeier

International water law plays a key role in guiding states’ behavior over water resources they share. Substantive and procedural principles provide an ex ante framework based on which states can interact in a manner that prevents or mitigates potential conflicts and fosters cooperation and its benefits while supporting the sustainable use and management of these transboundary resources. Through the international water law regime, cooperation has largely prevailed over conflict in the world’s transboundary basins. Nonetheless, international water law—and thus also its role in conflict prevention and cooperation promotion—faces various challenges as populations and economies grow, the climate changes, and states seem to increasingly value short-term unilateral considerations over long-term multilateralism gains. This will challenge key principles, such as the principle of equitable and reasonable utilization and the principle of no significant harm, and their implementation in different basins, possibly triggering new disagreements between riparian states. It will therefore be important for international water law to remain adaptive to change and ensure the long-term cooperative and sustainable governance of water resources shared between states.

Article

Groundwater Models  

Timothy M. Weigand, Matthew W. Farthing, and Casey T. Miller

Groundwater modeling is widely relied upon by environmental scientists and engineers to advanced understanding, make predictions, and design solutions to water resource problems of importance to society. Groundwater models are tools used to approximate subsurface behavior, including the movement of water, the chemical composition of the phases present, and the temperature distribution. As a model is a simplification of a real-world system, approximations and uncertainties are inherent to the modeling process. Due to this, special consideration must be given to the role of uncertainty quantification, as essentially all groundwater systems are stochastic in nature.

Article

Economics of Water Scarcity in China  

Yong Jiang

Water scarcity has long been recognized as a key issue challenging China’s water security and sustainable development. Economically, China’s water scarcity can be characterized by the uneven distribution of limited water resources across space and time in hydrological cycles that are inconsistent with the rising demand for a sufficient, stable water supply from rapid socioeconomic development coupled with a big, growing population. The limited water availability or scarcity has led to trade-offs in water use and management across sectors and space, while negatively affecting economic growth and the environment. Meanwhile, inefficiency and unsustainability prevail in China’s water use, attributable to government failure to account for the socioeconomic nature of water and its scarcity beyond hydrology. China’s water supply comes mainly from surface water and groundwater. The nontraditional sources, wastewater reclamation and reuse in particular, have been increasingly contributing to water supply but are less explored. Modern advancement in solar and nuclear power development may help improve the potential and competitiveness of seawater desalination as an alternative water source. Nonetheless, technological measures to augment water supply can only play a limited role in addressing water scarcity, highlighting the necessity and importance of nontechnological measures and “soft” approaches for managing water. Water conservation, including improving water use efficiency, particularly in the agriculture sector, represents a reasonable strategy that has much potential but requires careful policy design. China’s water management has started to pay greater attention to market-based approaches, such as tradable water rights and water pricing, accompanied by management reforms. In the past, these approaches have largely been treated as command-and-control tools for regulation rather than as economic instruments following economic design principles. While progress has been made in promoting the market-based approaches, the institutional aspect needs to be further improved to create supporting and enabling conditions. For water markets, developing regulations and institutions, combined with clearly defining water use rights, is needed to facilitate market trading of water rights. For water pricing, appropriate design based on the full cost of water supply needs to be strengthened, and policy implementation must be enforced. An integrated approach is particularly relevant and greatly needed for China’s water management. This approach emphasizes integration and holistic consideration of water in relation to other resource management, development opportunities, and other policies across scales and sectors to achieve synergy, cost-effectiveness, multiple benefits, and eventually economic efficiency. Integrated water management has been increasingly applied, as exemplified by a national policy initiative to promote urban water resilience and sustainability. While economics can play a critical role in helping evaluate and compare alternative measures or design scenarios and in identifying multiple benefits, there is a need for economic or social cost–benefit analysis of China’s water policy or management that incorporates nonmarket costs and benefits.

Article

Rethinking Conflict over Water  

Scott M. Moore

It has long been accepted that non-renewable natural resources like oil and gas are often the subject of conflict between both nation-states and social groups. But since the end of the Cold War, the idea that renewable resources like water and timber might also be a cause of conflict has steadily gained credence. This is particularly true in the case of water: in the early 1990s, a senior World Bank official famously predicted that “the wars of the next century will be fought over water,” while two years ago Indian strategist Brahma Chellaney made a splash in North America by claiming that water would be “Asia’s New Battleground.” But it has not quite turned out that way. The world has, so far, avoided inter-state conflict over water in the 21st century, but it has witnessed many localized conflicts, some involving considerable violence. As population growth, economic development, and climate change place growing strains on the world’s fresh water supplies, the relationship between resource scarcity, institutions, and conflict has become a topic of vocal debate among social and environmental scientists. The idea that water scarcity leads to conflict is rooted in three common assertions. The first of these arguments is that, around the world, once-plentiful renewable resources like fresh water, timber, and even soils are under increasing pressure, and are therefore likely to stoke conflict among increasing numbers of people who seek to utilize dwindling supplies. A second, and often corollary, argument holds that water’s unique value to human life and well-being—namely that there are no substitutes for water, as there are for most other critical natural resources—makes it uniquely conductive to conflict. Finally, a third presumption behind the water wars hypothesis stems from the fact that many water bodies, and nearly all large river basins, are shared between multiple countries. When an upstream country can harm its downstream neighbor by diverting or controlling flows of water, the argument goes, conflict is likely to ensue. But each of these assertions depends on making assumptions about how people react to water scarcity, the means they have at their disposal to adapt to it, and the circumstances under which they are apt to cooperate rather than to engage in conflict. Untangling these complex relationships promises a more refined understanding of whether and how water scarcity might lead to conflict in the 21st century—and how cooperation can be encouraged instead.

Article

Ecosystem Services into Water Resource Planning and Management  

Phoebe Koundouri, Angelos Alamanos, Kostas Dellis, Conrad Landis, and Artemis Stratopoulou

The broad economic notion of ecosystem services (ES) refers to the benefits that humans derive, directly or indirectly, from ecosystem functions. Provisioning ES refer to human-centered benefits that can be extracted from nature (e.g., food, drinking water, timber, wood fuel, natural gas, oils, etc.), whereas regulating ES include ecosystem processes that moderate natural phenomena (pollination, decomposition, flood control, carbon storage, climate regulation, etc.). Cultural ES entail nonmaterial benefits accruing to the cultural advancement of people, such as the role of ecosystems in national and supranational cultures, recreation, and the spur of knowledge and creativity (music, art, architecture). Finally, supporting ES refer to the main natural cycles that nature needs to function, such as photosynthesis, nutrient cycling, the creation of soils, and the water cycle. Most ES either depend on or provide freshwater services, so they are linked to water resources management (WRM). The concept of ES initially had a pedagogical purpose to raise awareness on the importance of reasonable WRM; later, however, it started being measured with economic methods, and having policy implications. The valuation of ES is an important methodology aimed at achieving environmental, economic and sustainability goals. The total economic value of ecosystems includes market values (priced) as well as nonmarket values (not explicit in any market) of different services for humanity’s benefit. The valuation of ES inherently reflects human preferences and perceptions regarding the contribution of ecosystems and their functions to the economy and society. The ES concept and associated policies have been criticized on the technical weaknesses of the valuation methods, interdisciplinary conflicts (e.g., ecological vs. economic perception of value), and ethical aspects on the limits of economics, nature’s commodification, and its policy implications. Since valuation affects the incentives and policies aimed at conserving key ES, e.g., through payment schemes, it is important to understand the way that humans decide and develop preferences under uncertainty. Behavioral economics attempts to understand human behavior and psychology and can help to identify appropriate institutions and policies under uncertainty that enhance ecosystem services that are key to WRM.

Article

Institutional Fit in the Water Sector  

Cathy Rubiños and Maria Bernedo Del Carpio

Adequate water governance is necessary for the world’s sustainability. Because of its importance, a growing literature has studied ways to improve water governance, beginning in the early 2000s. Institutions, which refer to the set of shared rules, codes, and prescriptions that regulate human actions, are a particularly important element of sustainable water governance. Evidence shows that to design institutions that will generate sustainable economic, ecological, and cultural development, it is necessary to consider ecosystems and socioeconomic-cultural systems as social-ecological systems (SESs). In the past, practitioners and international agencies tried to find the government-led panaceas, but this search has been largely unsuccessful. Current views support efforts to move towards addressing complexity (e.g., Integrated Water Resources Management), and search for the fit between the institutional arrangements and SESs’ attributes. The literature on institutional fit in SESs encourages planners to design institutions by carefully considering the defining features of the problems they are meant to address and the SES context in which they are found. This literature has been developing since the 1990s and has identified different types of misfits. A comprehensive fitness typology that includes all the different types of fitness (ecological, social, SES, and intra-institutional fit) helps organize existing and future work on institutional fit and provides a checklist for governments to be used in the problem-solving process for increasing fitness. The water governance and institutional fitness literature provide examples of management practices and mechanisms for increasing institutional fit for each fitness type. Future research should focus on improving the methodologies to measure different types of fit and testing the effect of introducing fit on SES outcomes.

Article

Water Resources Planning Under (Deep) Uncertainty  

Riddhi Singh

Public investments in water infrastructure continue to grow where developed countries prioritize investments in operation and maintenance while developing countries focus on infrastructure expansion. The returns from these investments are contingent on carefully assessed designs and operating strategies that consider the complexities inherent in water management problems. These complexities arise due to several factors, including, but not limited to, the presence of multiple stakeholders with potentially conflicting preferences, lack of knowledge about appropriate systems models or parameterizations, and large uncertainties regarding the evolution of future conditions that will confront these projects. The water resources planning literature has therefore developed a variety of approaches for a quantitative treatment of planning problems. Beginning in the mid-20th century, quantitative design evaluations were based on a stochastic treatment of uncertainty using probability distributions to determine expected costs or risk of failure. Several simulation–optimization frameworks were developed to identify optimal designs with techniques such as linear programming, dynamic programming, stochastic dynamic programming, and evolutionary algorithms. Uncertainty was incorporated within existing frameworks using probability theory, using fuzzy theory to represent ambiguity, or via scenario analysis to represent discrete possibilities for the future. As the effects of climate change became palpable and rapid socioeconomic transformations emerged as the norm, it became evident that existing techniques were not likely to yield reliable designs. The conditions under which an optimal design is developed and tested may differ significantly from those that it will face during its lifetime. These uncertainties, wherein the analyst cannot identify the distributional forms of parameters or the models and forcing variables, are termed “deep uncertainties.” The concept of “robustness” was introduced around the 1980s to identify designs that trade off optimality with reduced sensitivity to such assumptions. However, it was not until the 21st century that robustness analysis became mainstream in water resource planning literature and robustness definitions were expanded to include preferences of multiple actors and sectors as well as their risk attitudes. Decision analytical frameworks that focused on robustness evaluations included robust decision-making, decision scaling, multi-objective robust decision-making, info-gap theory, and so forth. A complementary set of approaches focused on dynamic planning that allowed designs to respond to new information over time. Examples included adaptive policymaking, dynamic adaptive policy pathways, and engineering options analysis, among others. These novel frameworks provide a posteriori decision support to planners aiding in the design of water resources projects under deep uncertainties.

Article

Multi-Objective Robust Planning Tools  

Jazmin Zatarain Salazar, Andrea Castelletti, and Matteo Giuliani

Shared water resource systems spark a number of conflicts related to their multi sectorial, regional, and intergenerational use. They are also vulnerable to a myriad of uncertainties stemming from changes in the hydrology, population demands, and climate change. Planning and management under these conditions are extremely challenging. Fortunately, our capability to approach these problems has evolved dramatically over the last few decades. Increased computational power enables the testing of multiple hypotheses and expedites the results across a range of planning alternatives. Advances in flexible multi-objective optimization tools facilitate the analyses of many competing interests. Further, major shifts in the way uncertainties are treated allow analysts to characterize candidate planning alternatives by their ability to fail or succeed instead of relying on fallible predictions. Embracing the fact that there are indeterminate uncertainties whose probabilistic descriptions are unknown, and acknowledging relationships whose actions and outcomes are not well-characterized in planning problems, have improved our ability to perform diligent analysis. Multi-objective robust planning of water systems emerged in response to the need to support planning and management decisions that are better prepared for unforeseen future conditions and that can be adapted to changes in assumptions. A suite of robustness frameworks has emerged to address planning and management problems in conditions of deep uncertainty. That is, events not readily identified or that we know so little about that their likelihood of occurrence cannot be described. Lingering differences remain within existing frameworks. These differences are manifested in the way in which alternative plans are specified, the views about how the future will unfold, and how the fitness of candidate planning strategies is assessed. Differences in the experimental design can yield diverging conclusions about the robustness and vulnerabilities of a system. Nonetheless, the means to ask a suite of questions and perform a more ambitious analysis is available in the early 21st century. Future challenges will entail untangling different conceptions about uncertainty, defining what aspects of the system are important and to whom, and how these values and assumptions will change over time.

Article

Well Construction, Cones of Depression, and Groundwater Sharing Approaches  

Fidel Ribera Urenda

The importance of groundwater has become particularly evident in the late 20th and early 21st centuries due to its increased use in many human activities. In this time frame, vertical wells have emerged as the most common, effective, and controlled system for obtaining water from aquifers, replacing other techniques such as drains and spring catchments. One negative effect of well abstraction is the generation of an inverted, conically shaped depression around the well, which grows as water is pumped and can negatively affect water quantity and quality in the aquifer. An increase in the abstraction rate of a specific well or, as is more common, an uncontrolled increase of the number of active wells in an area, could lead to overexploitation of the aquifer’s long-term groundwater reserves and, in some specific contexts, impact water quality. Major examples can be observed in arid or semi-arid coastal areas around the world that experience a high volume of tourism, where aquifers hydraulically connected with the sea are overexploited. In most of these areas, an excessive abstraction rate causes seawater to penetrate the inland part of the aquifer. This is known as marine intrusion. Another typical example of undesirable groundwater management can be found in many areas of intensive agricultural production. Excessive use of fertilizer is associated with an increase in the concentration of nitrogen solutions in groundwater and soils. In these farming areas, well design and controlled abstraction rates are critical in preventing penetrative depression cones, which ultimately affect water quality. To prevent any negative effects, several methods for aquifer management can be used. One common method is to set specific abstraction rules according to the hydrogeological characteristics of the aquifer, such as flow and chemical parameters, and its relationship with other water masses. These management plans are usually governed by national water agencies with support from, or in coordination with, private citizens. Transboundary or international aquifers require more complex management strategies, demanding a multidisciplinary approach, including legal, political, economic, and environmental action and, of course, a precise hydrogeological understanding of the effects of current and future usage.

Article

Input–Output Models Applied to Environmental Analysis  

Joaquim J.M. Guilhoto

Input–Output (I–O) models and analysis were originally conceived by the Nobel Prize winner Wassily Leontief in the 1930s as a tool that can be used by economists and economic policy makers to help in their decision process. The I–O models provide a “picture” of how the economy works, that is, what are the necessities to produce goods and services, how this production generates income, profits and taxes, and how this income is spent. In a simplified way the I–O models can be seen as the model implementation of the economy circular-flow diagrams usually shown in economics introductory courses. Associated with the theory behind I–O models and analysis, I–O tables contain the empirical information necessary to implement these models and theory. Taking, for example, the production of computer screens: • On the production side, the I–O models have information on: (a) how much is spent on the inputs, goods and services necessary to produce the screens; (b) whether these inputs have their origin in the domestic market or are imported; (c) how much was paid in tax to the government; (d) what was the total amount paid in wages and salaries; (e) what were the profits of the producing firms; (f) how many computer screens are sold on the domestic market or on the international market (exported); and (g) whether they are sold directly to the final consumer or are used as a production input, that is, incorporated into other goods, for example, a refrigerator with a computer screen; • On the demand side, the I–O models, taking into consideration the total income received by the different players in the economy, that is, households, firms, and government, have information on: (a) how the income of these players is spent on goods and services, and whether it is used for consumption or investment; (b) whether these goods and services were produced domestically or abroad (imported); and (c) how much consumer tax was paid. From the aforementioned structure of I–O models, and using economic mathematical models, it is possible to measure the direct and indirect inputs needed to produce goods and services in the economy, for example, to produce a car there is no need for agricultural goods as a direct input for production, but the fabric used in the car seats or on the car carpets could have come from cotton, which is an agricultural good, so, cotton is an indirect input used in car production. I–O models, by their capability to show a complete picture of the economic system, and tracing of the origin of direct and indirect inputs used in the production process, can be used in environmental studies by linking economic and environmental variables, on the production and consumption sides. From the production side it is possible to measure, by considering the direct and indirect inputs used, how many natural resources were used and how much pollution was generated in producing the goods and services. On the demand side it is possible to measure the environmental variables, natural resources, and pollution, embodied in the goods and services consumed in the economy. Expanding I–O models to a global scale, that is, using inter-country I–O models, it is possible to measure the environmental impacts, and contents, of the goods and services by country of origin of production and by countries of consumption.