Water, Where Do We Stand?

Julio Be rbe I, Alfonso Exposito,

Carlos Gutierrez-Martfn, and Carlos D. Perez-Bianco


Water is essential for human welfare and for sustaining Earth’s ecosystems. This natural resource constitutes a critical input for all economic sectors, but it is also a significant element for a wide variety of cultural and societal purposes. Population growth, changes in land-use patterns (e.g., agricultural intensification, urbanization), and globalization all incur significant human pressure on the availability of fresh water, both from surface and groundwater resources, thus influencing its qualitative and quantitative status. The world as we know' it today is threatened by a growing and unbalanced demand for water, increasing w'ater scarcity and pollution, climate change, and the effects of inadequate w'ater management instruments and w'ater governance decisions. Most of these threats and challenges are present on a global scale, thus requiring an international plan of action. Nevertheless, society generally faces significant difficulties when dealing with global challenges, particularly when these challenges require bilateral or multilateral cooperation between countries. This is illustrated by the slow' development of international agreements for the improvement of global governance of water resources. Water has at the latest been considered a crucial resource for sustainable development since the United

Nations (UN) Commission on Sustainable Development adopted the declaration “Strategic Approaches to Freshwater Management” in 1998 (Cosgrove and Loucks

2015). In recent years, the concept of global water governance has grown in relevance in the international political agenda and has triggered a wide range of declarations and cooperation initiatives developed by various international organizations (e.g., Food and Agriculture Organization [FAO], Organisation for Economic Co-operation and Development [OECD], UN, World Bank). Several UN Sustainable Development Goals (SDGs) related to water provide good examples. These initiatives aim to include the consideration of w'ater-resource management within the wider political objectives of specific action programs and to assure sustainable, efficient, and equitable development thereof.

Not only does this chapter offer a brief but complete overview of the current scenario of where we stand regarding the use of water resources on a global scale and the challenges to be faced in the near future, but it also discusses the governance and management solutions that can be used to help face these challenges. After this introductory section, this chapter analyzes the current status of water resources on a global scale, as well as the observed current demand (Section 2.2) and supply trends (Section 2.3). Potential future scenarios and challenges are also discussed. Future challenges affecting world water resources include the impacts of climate change and its associated risks (e.g., higher frequency of drought and flood events); water resources also occupy a significant place because before middle of the twenty-first century, global warming is likely to reach a 1.5°C increase unless decisive action is taken by governments worldwide (Intergovernmental Panel on Climate Change [IPCC] 2018). Rising temperatures will affect precipitation patterns and evapotranspiration, in turn affecting all of Earth’s ecosystems, including human societies. These challenges are briefly reviewed in Section 2.4. To deal with these challenges and to guarantee a more sustainable use of water resources, alternative management instruments can be used, both on the supply and demand sides. A review of these instruments is offered in Section 2.5. In this respect, an optimal water policy mix should include various instruments from both the supply and demand sides, including economic and noneconomic instruments. As water demand continues to rise, water economies are progressively reaching a maturity phase in which incremental provision costs result in an inelastic supply schedule, and the financial and environmental costs of developing new water storages have begun to exceed the economic benefits in the least productive (marginal) uses of existing supplies (Exposito and Berbel 2017; Randall 1981). At this point, the focus needs to shift from meeting demands to reallocating available resources so that the societal goals of efficiency, robustness, and resiliency are all met. From an integrated water-resource management (IWRM) perspective, this is addressed through the combination of supply-and-demand policies that ensure the best ecological status of water bodies at the least cost (United Nations [UN] 2012). Furthermore, an adequate governance framework is needed to support the implementation of the selected mix of water management instruments within a complex society w'ith alternative (and often conflicting) interests, groups of stakeholders, and objectives. Section 2.6 aims to offers several proposals on governance issues.


The water consumption worldwide has grown 800% over the last century, and for the near future, the world’s population is projected to reach 9.8 billion in 2050 (UN 2018), with per capita income more than doubling by 2050. This higher income will also result in greater calorific intakes and changes in diets with an increase in the proportion of meat and dairy consumed, especially in developing countries (Alexandratos and Bruinsma 2012). The current nutrition transition in developing countries is based on the rapid growth in fat from edible plant oils and the increase in the consumption of animal products (Le Mouel et al. 2018). This combination of increased intake and dietary changes will generate an increase in demand for primary food production and, therefore, for water resources (Worldwatch Institute [WWI] 2018). Nachtergaele et al. (2011) estimate an increase in food demand (in terms of calories intake plus diet changes) in the period 2010-2050 that will require a 100% increase in crop production. The resources to cover this demand increase may come from marine, rain-fed, or irrigated agricultural areas. Nevertheless, a small increase (4%) in cultivated land is expected from 2007/2009 to 2050 (Alexandratos and Bruinsma 2012). Estimations of growth in irrigated land from 2007/2009 to 2050 is more variable and ranges from 4% (Alexandratos and Bruinsma 2012) to 11% (Nachtergaele et al. 2011). Most of the expansion of irrigated land is achieved by converting rain-fed land to irrigated land, although a minor part will take place on currently uncultivated desert land. Nevertheless, some cultivated land will be lost either as a result of deterioration or urbanization.

The share of rain-fed production in global food supply is expected to decline from 65% (2010) to 48% (2050) (Nachtergaele et al. 2011) because of the expected increase of irrigated land worldwide. This will lead to a significant increase in irrigation water withdrawals. Nachtergaele et al. (2011) estimate this increase around 11% in the period 2010- 2050, and Spears (2003) considers that this could be close to 80%. The lower estimation matches the expected growth in irrigated area because intensification is not considered. Contrasting with the aforementioned increase in agricultural water withdrawal as forecast by authors specializing in the field of agricultural economics and food policy, the OECD estimates an 8% reduction in water use (2050 vs. 2010). The predictions by OECD are probably optimistic and fail to consider an increase of 11% in irrigated area for 2050 (required to satisfy increased food demand). As agricultural water withdrawal constitutes 70% of the total productive use of water resources, the precise estimate of the growth in the use of irrigation water presents a critical issue for estimation of future water demand.

Regarding the impact of climate change on water demand, it is subject to uncertainty but even if the same average precipitation is maintained, then there will be an increase in temperature, and this in turn will cause increased evapotranspiration. This effect may increase water consumption and withdrawal from agriculture over the optimistic 11% (2050 vs. 2000) predicted by FAO (Alexandratos and Bruinsma 2012), which considers that the irrigation requirement per cultivated hectare (measured in m3/ha) remains stable. Nevertheless, we will use this “optimistic” value for our projections in the rest of this section.

In addition to agriculture, higher energy consumption, greater population, and increased urbanization will significantly increase the water demand for nonagricultural use (Exposito et al. 2019). Changes in energy consumption will be critical for water.

According to the World Energy Council (WEC 2013), energy production is expected to increase from 2010 to 2050 in the range of 27% and 61% (depending on the scenario of energy mix and prices), whereas OECD (2012) forecasts a growth around 40% (2050 vs. 2000), which implies an increase in water use for energy production of around 76%.

The growth in urbanization and per capita income will be translated into higher demand for domestic and municipal uses for horizon 2050, estimated at 183% over the 2000 levels (OECD 2012). Finally, manufacturing is expected to grow' significantly because the world GDP is expected to quadruple from 2000 to 2050, and the water withdrawal for manufacturing is expected to increase 309% in this same period (OECD 2012). The combined increase of water withdrawals for all sectors is as follows: 9% for agriculture, 176% for energy, 309% for manufacture, and 83% for municipality uses; this implies a combined increase of 56% of total withdrawals (all sectors considered) in the period 2010-2050. In Table 2.1, several projections, as used by the aforementioned international institutions, have been integrated.

This global increase will exert various local impacts because more than half of the world’s projected 9.8 billion people will live in water-stressed regions by 2050 (Schlosser et al. 2014). The regions that are currently under severe stress generally have a greater dependence on groundwater resources because most of them are currently overexploited (Wada and Bierkens 2014; Wada et al. 2012). Gleeson et al. (2012) estimate 1.7 billion people live in areas w'here groundwater resources are under threat from overexploitation.

These estimations show a pessimistic situation: already overexploited aquifers, a significant percentage of food coming from nonrenew'able resources, and the fact that water withdrawal is expected to grow by around 60% by 2050. The good new's is that the hydro- logical cycle determines that a great part of this water can be reused with reference values of return flow's compared with withdrawal of around 40% for agriculture, 95% for energy (cooling), and 80% for urban and manufacturing uses (European Commission [EC] 2012). When return flows are taken into account, part of the increase in water withdrawal can be replenished with direct (wastewater reuse) or indirect w'ater reuse (water discharge in the surface water such as river, lakes, and aquifers) that can be later reused.


World Scenarios of Water Withdrawal by Sector

2010 (kmVyear)

2030 (kmVyear)

2050 (kmVyear)

Increase (%) 2050 vs. 2010


























Source: “OECD, OECD Environmental Outlook to 2050: The consequences of Inaction, OECD Publishing, Paris, 2012; bAlexandratos, N. and Bruinsma, J., World Agriculture towards 2030/2050: The 2012 Revision, ESA Working paper No. 12-03. FAO, Rome, 2012.

A critical question regarding water reuse is that of quality because, on a global scale, the predicted intensification of agricultural production for the growing population will drive growth in the consumption of fertilizers by around 20% on average by 2030, with India and China dominating in this respect. According to Bodirsky et al. (2014), nitrogen (N) pollution in 2050 can be expected to rise in a range of 102%—156% compared to 2010 values, meanwhile N and phosphorus (P) discharges from urban sources are estimated to multiply by a factor of 2 at global level (2050 vs. 2005) (Van Drecht et al. 2009). Furthermore, according to the UN (Ryder 2017), by 2050 1.4 billion people are projected to remain without access to basic sanitation. Even if we assume that part of these return flows can be reused, and consequently that pressure on freshwater withdrawal can be reduced, certain water users act as a critical constraint in the system. This is the case of nuclear power stations, which require a guaranteed water supply and constrain water use in the basin even when their real consumption (via evaporation) is small.

In this context of increasing water demand, the forecast increase in water withdrawals of around 60% (2050 vs. 2000) in a baseline optimistic scenario requires the implementation of innovative models of governance aimed to increase efficiency in resource use, enhance supply quality, and improve the use of an effective mix of management instruments (e.g., water pricing, market-based instruments, collective action of implied stakeholders).

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