Water management: Current and future challenges and research directions

Abstract

Water distinguishes our planet compared to all the others we know about. While the global supply of available freshwater is more than adequate to meet all current and foreseeable water demands, its spatial and temporal distributions are not. There are many regions where our freshwater resources are inadequate to meet domestic, economic development and environmental needs. In such regions, the lack of adequate clean water to meet human drinking water and sanitation needs is indeed a constraint on human health and productivity and hence on economic development as well as on the maintenance of a clean environment and healthy ecosystems. All of us involved in research must find ways to remove these constraints. We face multiple challenges in doing that, especially given a changing and uncertain future climate, and a rapidly growing population that is driving increased social and economic development, globalization, and urbanization. How best to meet these challenges requires research in all aspects of water management. Since 1965, the journal Water Resources Research has played an important role in reporting and disseminating current research related to managing the quantity and quality and cost of this resource. This paper identifies the issues facing water managers today and future research needed to better inform those who strive to create a more sustainable and desirable future.

1 Human Ambitions and Earth's Limits

Throughout the world, demographic, economic, and technological trends have accelerated our ability to knowingly and unknowingly modify the environment we live in and that sustains us. We humans have become the principal driver of environmental change. Our actions are impacting our global environment, including our climate. This in turn impacts the amounts and spatial and temporal distributions of precipitation that falls on watersheds and the timing of its runoff. Coupled with changes in landscapes, due to growth in food and energy production and from the movement of people into urban centers, we are altering the quantity and quality of our freshwater resources on which we depend to survive, both physically and economically. We depend on water not only for life itself, but indeed for our economic wellbeing as well. Water plays a role in the creation of everything we produce. There are no substitutes and while it is renewable there is only a finite amount of it.

In the past, we have made decisions regarding the management of our water resources that have not always helped us become more secure or sustainable. We have disrupted and overallocated river flow regimes—sometimes to the point of drying them up, along with their downstream lakes. We have overdrawn groundwater aquifers; polluted many, if not most of our water bodies including estuaries, coastal zones and even oceans; and degraded ecosystems. We have done this mainly to satisfy short-term economic goals, often goals that may not have included the long-term environmental—or even economic—sustainability of region or basin, and indeed our own health.

Our planet no longer functions in the way it once did. Earth is currently confronted with a relatively new situation, the ability of humans to transform the atmosphere, degrade the biosphere, and alter the lithosphere and hydrosphere. The challenges of our current decade—resource constraints, financial instability, religious conflict, inequalities within and between countries, environmental degradation—all suggest that business-as-usual cannot continue.

These challenges to effective planetary stewardship must be addressed and soon. The various parts of the Earth system – rock, water, and atmosphere – are all involved in interrelated cycles where matter is continually in motion and is used and reused in the various planetary processes. Without interlocked cycles and recycling, the components of our Earth could not function as an integrated system.

In the last 50 years or so we have come to recognize the movements in all Earth's layers, including the plates at the surface, the mantle and the core as well as the atmosphere and ocean. The momentum and acceleration of the impacts of business as usual threaten to tip the complex Earth System out of the environment in which everything living on this Earth has evolved and developed. Some call this new geological period the Anthropocene [Crutzen, 2002; Williams et al., 2011]. Water is becoming a central issue in this new period. This applies not only to freshwater systems but also to the oceans, their levels and what lives in them. The interdependency between social or human ambitions on the one hand, and availability and quality of our natural resources and the environment on the other, is obvious; it determines the kind of development that is realistic and stable.

The expansion in the production and supply of goods and services in the recent past has meant more jobs, income, and, generally, greater possibilities for a better life. It has also meant an increase in the use and pollution of natural resources. The adverse effects on water and other vital components of the Earth System are evident. Many river basins in the world are labeled as “closed” or are on the verge of being closed; their flows no longer reach the oceans [Seckler, 1996; Gleick and Palaniappan, 2010]. An estimated 1.4 billion people live in closed basins [Smakhtin, 2008] with more limited development options. The development of potential flood zones along rivers and coastlines has increased the incidence and impact of flood-related damages. According to the World Health Organization (WHO) [2007], during the last decade of the last century about two billion people were victims of natural disasters, 85% of which were floods and droughts.

There is no escape from the fact that the need and demand for finite and vulnerable water will continue to expand and so will competition for it. More uncertainty in water availability, higher frequency of extreme weather events, and more rapid return flows of water to the atmosphere are expected in the future. Given the changes in the hydrologic cycle as a result of land use and climate changes and the closed character of many basins, allocations to, and patterns of future water use, will deviate from past trends.

Research is needed to better understand how these complex interactions may develop over the coming decades and the associated social, political, and environmental implications. Clearly, water issues will become even more important in the lives and activities of people [Cosgrove and Rijsberman, 2000; Grayman et al., 2012].

1.1 Freshwater Stress

Today everyone is concerned about the potential water scarcity in the face of increasing, mainly population-driven, water demands, and its consequences on our energy and food production. The Global Risk Perception Survey conducted among 900 recognized experts by the World Economic Forum reports that the highest level of societal impact over the next 10 years will be from water crises. http://www3.weforum.org/docs/WEF_Global_Risks_2015_Report15.pdf

In recent decades the percentage increase in water use on a global scale has exceeded twice that of population growth. This has led to more, and larger, regions in the world being subject to water stress where the current restricted rates of water use and consumption, let alone the desired rates, are unsustainable. Water demands and supplies are changing. What they will be in the future is uncertain, but it is certain that they will change. Demands are driven in part by population growth and higher per capita water consumption in growing urban, domestic, and industrial water sectors.

By 2050, the world will have to feed and provide energy for an additional 2–2.5 billion people as well as meet the current unsatisfied power needs of a billion. To meet the nutritional needs of this additional population, we should consider the amount of water that is consumed in the production of different goods and, in particular, energy and food. Energy and food security are demands that are particularly critical to water managers. Energy production, water, food security, and climate change are all connected through interactions and feedbacks. For example, the growing, transportation, processing, and trading of food products require large amounts of water and energy. A complete analysis is provided by the Comprehensive Assessment of Water Management in Agriculture [International Water Management Institute (IWMI), 2007]. This work demonstrates that in a business-as-usual scenario, water consumption in agriculture would almost double.

Per capita water use varies considerably over the globe. In developed regions one can assume an average value of 200 L per person per day. The value adopted internationally for basic human water needs is about 50 L per person per day [Gleick, 1996]. The amount of water each person in the USA uses is on average is much higher depending on a number of factors, in particular diet, but also in all the water required to make all the energy and nonagricultural products consumed. A recent report on water consumption in the USA shows reductions in all sectors: including agriculture; municipal and industrial; and thermoelectric power. But the report concludes that while substantial progress has been made, current water use trends are not sustainable in the face of population growth and climate change [Donnelly and Cooley, 2015].

Water is increasingly becoming a priority policy issue at the international level. The third United Nations World Water Development Report [United Nations World Water Assessment Programme (UN WWAP), 2009] warns, in an unprecedented fashion, that extremely serious consequences may result from the current inequitable, unsustainable use of water. Both economic development and security are placed at risk by poor water management. That is why the concern about a global energy crisis has recently begun to be accompanied by a concern about a looming global water crisis. The energy and water nexus expressed both by the effects of water use on energy consumption and by the effects of energy production on water consumption, is gaining increasing attention [see e.g., Hoff, 2011; World Economic Forum Water Initiative (WEFWI), 2011, UN WWAP, 2011, 2012, 2014].

1.2 Globalization

Increasing globalization is motivating the implementation of new rules and procedures for the international trade of goods and services, reflecting the increasing influence of multinational firms engaged indirectly in water use and transfers. This globalization of trade has wide-ranging implications for consumers, governments, and the environment. While bulk water is not commonly traded, except for relatively limited quantities in bottles, the water used to produce the goods that are traded across borders, called virtual water, can have a major impact on water balances in basins and regions. The US is the world's largest exporter of virtual water [Hoekstra and Chapagain, 2008].

The impact of globalization on water may be considered from two other perspectives: the negative effects on water of the growing integration of the world economy, in particular concerning water contamination and associated environmental degradation; and water itself as an object of global trade policies.

Some natural resources, such as oil, natural gas, wood, agricultural products, or fish have, for a long time, been traded in international markets without becoming a political issue. Not so with regard to water. Water is different than many other natural resources that are traded because the costs of transport are very significant in comparison to the understated economic value of water and, perhaps more importantly, because of perceptions about the human right to water, and objections to the commodification of the resource [Gleick et al., 2002; Hoekstra and Chapagain, 2008].

International projects involving water transfer often raise concern and controversy. However, one form of “trade,” which is generally accepted without raising special problems, is the natural flow of water among countries sharing a river basin or aquifer. This transaction is normally ruled by political agreements, rather than trade agreements. In practice, only a comparatively small number of agreements for the long distance trade of raw water have been concluded. Water transportation is expensive and usually pursued only in rare cases where other practices, such as desalination, are not possible or economic. Almost all such efforts only provide water for very high-value industrial or domestic needs and not for other important uses, such as for food production.

Trade in high water consumptive goods from water scarce regions may be economically profitable in the short term but it is not viable in the long term and is a threat to meeting other water related goals. Pollution and environmental degradation are not transferred along with the products to the consumer. They are left behind for the producing country to deal with. Countries will need to revise policies to avoid incentivizing high water use for low value purposes and unsustainable export promotion. This is a very complex issue and requires much more research to find real water-trade links and to find possible solutions if trade is causing unsustainable water practices and reducing local availability of adequate water resources.

Trade policies and practices need to be aligned with the goal of sustainable water at global, regional and national levels and to support overall gains in water-use efficiency and providing incentives to countries to produce and trade goods in line with their specific water circumstances, while fully participating in fair, equitable and sustainable trade. Access to water may be a natural advantage (or disadvantage) that should be considered by the World Trade Organization in establishing trade regulations. This could be addressed in the ongoing WTO negotiations and WTO Doha Development Agenda and Hong Kong Ministerial Mandate. As water is an important requirement for the production of most, if not all traded goods, it is an important dimension of trade as it relates to the sustainable development goals (SDGs) and other forums mandated to develop trade-related policies and agreements.

1.3 Nonstationarity in Supply and Demand

Traditionally, water infrastructure and water management systems have been designed and constructed based on historical observations of climate and hydrological data and consumption trends, followed by statistical analysis and interpretations of these data to determine the probability of certain events occurring. For example, infrastructure is often designed to withstand an event that has a certain probability of occurring based on an analysis of the longest time series of historic data available. Infrastructure designed to withstand a 100 year flood is designed for a flood event that has a 1 % chance of occurring in any given year based on historical records. The implicit assumption in such calculations is that climate and hydrological systems behave as stationary systems, meaning that the statistical characteristics of, e.g., rainfall and discharge from a past time period in which data are available, will remain the same into the future. Water engineers and managers generally understand that this is not the case, but can only work with the information they have available, sometimes introducing safety factors in the hopes of covering uncertainty of data and future variability. Climate change now occurring makes it even more difficult to rely on this assumption of stationarity; historically observed data are no longer adequate to meaningfully plan for climate variability and extremes. Managers will need information about how climate change will affect probability in order to carry out risk-cost analyses of alternative investments in infrastructure needed in the future [Intergovernmental Panel on Climate Change (IPCC), 2001, 2007, 2012, 2014].

Natural and human systems have an ability to adapt to change to a certain extent with the existing knowledge and technology. These are called autonomous adaptations. Farmers, e.g., can adjust their crop mix and planting dates over time to allow for changes in quantity and timing of precipitation. Other adaptations require greater investment and institutional changes. Sticking with our example, farmers may need entirely new crop varieties, new irrigation infrastructure, and new education and processing facilities once changes move beyond the ranges that can be handled by autonomous adaptation. At some point, the risk may become unacceptable. In our example, this could be the point where the climate and land in an area are no longer suitable at all for agriculture.

Changes in climate can shift and alter the shape of the entire probability distribution of future hydrologic events and water demand. Both are uncertain. Evidence to date suggests we will be observing more variability, resulting in more frequent floods and droughts of greater intensity and duration. At the same time, demand for water for agriculture and energy production in particular will be influenced by climate change, technological development and urbanization and human responses. More investments will be needed for measures that will enhance adaptation at the regional, watershed and household levels, such as water storage structures, conjunctive use of groundwater and surface water, wastewater capture and reuse, agroforestry, and research that generates more resilient production systems for smallholders. More effort is required to protect and sustain upland areas and mountainous regions where much of the world's water supply originates. Water managers would like to have future supply and demand probability functions so as to provide the reliability, the quality, and the pressure of water supplies people expect.

Climate models are good at modeling the large scale processes for which they were designed, and they do well at showing average changes in temperature. However, precipitation is a more local process, and such models have not yet been able to accurately predict changes in precipitation or its variability at scales useful to water managers. Very little research has been done to date on future demand functions.

Decision makers want to know what options are available to them that will be robust under any scenario of the future. Our improved understanding of physical and social processes and trends, possible future changes, technologies, and management options and our ability to model them as systems can help us find solutions that can be effective now and adaptable across a wide range of feasible future states.

For example, there is a definite need for adaptation to climate change in coastal cities. An eight-step procedure has been in use for New York City's critical infrastructure and climate change evaluation:

Identify current and future climate hazards
Conduct risk assessment inventory of infrastructure and assets
Characterize risk of climate change on infrastructure
Develop initial adaptation strategies
Identify opportunities for coordination
Link strategies to capital and rehabilitation cycles
Prepare and implement adaptation plans
Monitor and reassess. [Grayman et al., 2012]

Research is required to inform this process.