{'fraction_non_alphanumeric': 0.02873475376761532, 'fraction_numerical': 0.017638247791397915, 'mean_word_length': 5.137711069418386, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The influence of hydro-climatological balances and Nature-based solutions (NBS) 
in the management of water resources

This article offers a historical review of (cognitive) scientific research that demonstrates the development of key concepts relating to balances in the hydrological and hydro-climatic cycles, thereby supplying a basis for quantitative and qualitative assessment of renewable water resources. The review reveals the direction knowledge took as it developed through successive cognitive and applied stages. The emphases are on how global and regional hydrological conditioning underpin integrated concepts for the management of water resources. The primary aim of this article is to describe the main achievements, approaches and scientific initiatives, along with their theoretical underpinnings, in the hope of encouraging application and further appreciation. Attention is thus paid to milestones along the road to global development, as manifested in the (at times abruptly changing) effort to better assess and understand the use of water resources in various economic, social and ecological activities. The aim is first and foremost to encourage the achievement of sustainable development as humankind’s main hope for the future. A further focus is on initiatives, scientific issues, and concepts that have been espoused by international organisations and illustrate the increasingly essential harmonious use of water resources at local, regional, continental, and planetary scales. Relevant global conferences have demonstrated wide readiness to adopt declarations, or to issue appeals and resolutions, in support of fuller assessment of renewable water resources. Examples of excessive use have been identified, and efforts have been made to counteract both floods and deficits, and hence avoid crises. These deliberations have also stimulated long-term forecasting, for periods up to 2030 or even 2050. Also stressed here are the challenges, inspirations, and achievements of pure and applied science when it comes assessing the risk that the Earth’s potential to supply water resources will be exceeded. The suitability of current assessments of water resources is evaluated, and reference made to ecologically-integrated answers such as Nature-based solutions (NBS), as backed by the UN and UNESCO (2018) in combination with principles set out in the EU’s Water Framework Directive (2000/60/EC).


FOREWORD
The water in various forms that is an essential component of the geosphere is also a basis for the existence of our planet's living world or biosphere. Although water is a renewable natural resource, its quantity is such that the matter and energy associated with its presence in the epi-geosphere are limited. Key features include ubiquitous presence and uses in various sectors of the economy. The consequence is that water is a common economic good of great importance. Nevertheless, water resources are more limited by the overriding impacts of demographic, economic, climatic, and other anthropogenic factors than they are by natural renewability.
The main subject of interest here is the renewability of terrestrial water resources, i.e. the entirety of actually or potentially available water of suitable quantity and quality to meet defined demands (Międzynarodowy Słownik Hydrologiczny 2001).
This article seeks to achieve a synthetic, historically-based conceptualisation of the science of water resources, through which increasingly complex and technologically advanced methods can inspire more effective assessment and use of water. From the outset, integration of theory and practice has been a key pragmatic element bringing water management closer to more favourable solutions for utilisation, planning, and management.
The background to this article's content and objectives is provided by the natural shaping of the water cycle and its components in the environment, as the basis for quantitative and qualitative environmental aspects and the regularities underpinning spatial and temporal changes.

IDEAS FROM SCIENCE AND PRINCIPAL CONCEPTS OF THE HYDROLOGICAL CYCLE
Natural water circulation can be quantified in the form of the water balance that represents a basis for the management of water resources in an area and is also of fundamental significance to nature conservation. A basis for the water-balance equation is to be found in "the law or principle of mass conservation" as formulated by Einstein (1879Einstein ( -1955 -the very famous German physicist, creator of the general and special theories of relativity, and the person who emphasised the constancy of mass and energy, with the two nevertheless being interconvertible. This kind of thinking may ultimately trace back to 15 th century de-scriptive formulations arrived at by Leonardo da Vinci, not least in the matter of the water cycle within a drainage basin (Richter 1956). Biswas (1970) considered that da Vinci's work had led Newton (1643Newton ( -1727 to his laws relating to the conservation of matter and energy, as well as gravitation. Circulation of water in nature as described by da Vinci makes visually clear the causes and consequences of many component processes that can be confirmed by simple measurement, attesting therefore to far-reaching scientific intuition about the interdependence of phenomena and factors. Premises supporting these concepts relate to spatial and temporal continuity and an unchanging quantity of water circulating in nature. Craig et al. (2001) followed earlier hydrologists and geophysicists in maintaining that the amount of water globally remained constant, whereas this idea was not confirmed in research from the first decade of the 21 st century, not least from American astrophysicist Lewis (2012).
Documenting the further growth of knowledge about water, Biswas (1965Biswas ( , 1970 mentions Pallissy, active around 1550 in France and the developer of ideas about the origins of precipitation in a river system, as well as springs and underground waters. These concepts then offered the basis for assessment of renewable resources, as indeed Galileo, Descartes, and Gastelle (17 th century) all proceeded to do.
Cognitive understanding of the hydrological cycle proceeded in stages. The American geophysicist Newton in his Encyclopedia of Water (2003) states that increased understanding reflected advances in measurement techniques, calculation methods, and scientific concepts, as accelerated by quantitative hydrology and mathematical modelling in the service of economic forecasts.
The development of water balances was thus dependent on the length of measurement series and the scale of the analysed object (for example, a drainage basin or a floodplain).
According to Biswas (1965Biswas ( , 1970Biswas ( , 1978, true development of scientific hydrology took place in the 17 th century, with the first more-precise methods of measuring flows then representing a milestone in the development of quantitative resource assessment. It was the second half of the 17 th century that brought the beginning of continental hydrology, much later termed global hydrology by Kalinin. Bierkens (2015) presented the contemporary state, trends, directions, and directives underpinning the development of knowledge about water resources.
Theoretical foundations for the assessment of water resources in scientific publications first gained support from real measurements from such large international rivers in Europe as the Elbe, Rhine, and Oder. Measurements began to cover a broader scale from the end of the 18 th century onwards, as intensive engineering work to regulate rivers was undertaken (see Biswas 1962after: Maass 1870. Representatives of the American engineering school associated with Stanford University in California, above all Linsley and Franzini (1972), devised strong theoretical foundations for the calculation of flowing water resources, as well as the behaviour of rivers at times of high-water events and flooding. From this point on, there was a broader movement seeking to put in place a rational model of calculating flows at times of flooding. The model was based on engineering studies involving 24-hour maximum precipitation and including factors such as evaporation, infiltration, and runoff via streams. Morley (1855), who was the biographer of Pallissy, thus dealt with a reconciling of theory and practice.
A key breakthrough in hydrology and its practical form (water engineering) was a modern handbook by Chow (1964) entitled the Handbook of Applied Hydrology. Even today it may not be described as outdated. In turn, those following the development of hydrology and water management in the USA should not ignore the modern Polish handbook from Lambor (1965), which offers a cohesive presentation of the relevant fundamentals, assessment methodologies, and management principles, as supported by numerous examples of problems and solutions arrived at on various continents and in many different regions.

INTERNATIONAL DIALOGUE AND PROGRAMMES CONNECTED WITH WATER RESOURCES AND MANAGEMENT
in the direction of joint international action, irrespective of whatever geopolitical blocs may be in place. It was on the initiative of that organisation that a first UN Conference on Water was convened at Mar del Plata (Argentina) in 1977. The main objective was an assessment of the status of water resources and a desire to assure all human beings access to water in appropriate quantity and of appropriate quality.
Attention was paid to the socio-economic need for the water present on the planet, with further requirements that efficiency of use be increased, along with states' readiness to act in the face of a looming global water crisis, at the time considered likely to make itself felt before the end of the 20 th century. and stressed the need for integrated water management, which accounts for economic, social, and environmental/ecological aspects, as well as regional specifics.
Interlinkages between the systems of thought globally represent an issue of overriding importance supported by the UN, not least via its High-Level Panel on Threats, Challenges and Change. We also need to recall the precursors from Scandinavia who had significant input into the development of the sustainable development concept, including the future role to be played by water. Those in question were the then (1977) Prime Minister of Norway, Gro Harlem Brundtland, as well as Malin Falkenmark of the Swedish Academy of Sciences (in 1987). They regarded as crucial a holistic approach to meeting social, cultural, economic, and environmental needs where the uses of water and the environment were concerned. The World Commission on Environment and Development's Our Common Future report (1987) refers to climate change and its consequences for desertification, forest degradation and felling, water shortages, and the threat to biodiversity at the levels of the species, the biome and the phytocoenosis, most especially wet-lands, which are dependent on sources of water. This report was a key stimulus for further ground-breaking action in the name of what became known as sustainable development goals.
Falkenmark (1983, 1984, 1987, and 1991), and other international studies justified the protection of water resources in line with the growing risk or probability of the Earth's potential being compromised by the excessive use of water. She also, individually (1987, 1989/1990), and together with da Cunha (1989Cunha ( /1990 and others (1991) Kindler (2018) and Varis et al. (2017) address the matter of worldwide use of water by reference to just a few dimensions of the protection of those resources essential to the production of food items (not least those to be imported or exported).
The end of the 21 st century's first decade brought many new actions focusing on the relationship between ecology, the reshaping of water resources under the influence of global warming, and the capacity of water balances and the hydrological cycle to go on supplying water. Attention is given to ecological processes that affect water quality and quantity, limitations on evapotranspiration, and the barriers to the consumption of water resources in extreme circumstances involving droughts or flooding. Rockström et al. (2014) -responding to Vörösmarty et al. (2010Vörösmarty et al. ( , 2013) -claim that a future bridge between ecohydrology and uncontrolled resistance on the part of the environment may give rise to dramatic Anthropocene phenomena and processes that will disrupt the sustainability of water resources worldwide.
Today the preference is for closed-cycle water management. This approach is economical with water resources and involves links in the chain that comprises abstraction from the environment, use, and discharge. Where there is considerable access to limited resources, synergies involving demographic processes (population increase), or a larger number of people placing a burden on the management of renewable resources, then renewability becomes limited and there is a lack of equilibrium that works to minimise values for resource use. The key issues for these accords address awareness of the use and consumption of water resources and special protection for areas of deficit or accumulation within cities. In each case excessive outflow is to be prevented, sustainability encouraged, amounts of wastewater reduced, and appropriate priorities determined. Drought represents a major challenge for agriculture, horticulture, livestock-raising, and forestry.
The distinguishing of the different types of water resources and their precise definitions (for example as green or grey water) reflects the way that water may be subject to various processes before it, for example, becomes effluent. It is possible to steer such resources, and engage in appropriate management or allocation of them.
Anticipated droughts and periods of low levels of surface water or groundwater as a reflection of global warming and excessive use have been worked on by Tallaksen and Van Lanen (2004). In turn, Veldkamp et al. (2015)  In sum, such extensive, multi-dimensional development of knowledge of quantitative assessment in water-cycle management and balancing must include mathematical modelling (deterministic, stochastic, or conceptual). Beyond hydrology, environmental, and ecological factors, models will need to address economic and demographic development scenarios.
The ultimate aim in each case is to make projections possible, with verification by way of measurement and monitoring, thereby supplying a basis for the forecasting of changes in the resource under the influence of various global and anthropogenic activities.

THE DEVELOPMENT OF WATER-BALANCE PROBLEMS AND CHALLENGES
As the content of previous sections makes clear, the cognitive development of the hydrological cycle was a very protracted, step-bystep process extending from the 16 th through the 19 th centuries. It centred on a developing understanding of genesis and interdependence, and the uncovering of empirical premises confirming variability across both space and time.
As Biswas (1965) shows, and Dooge (1959, 1974  The use of mass (or volume) balance as a means of both assessing and studying renewable water resources on the basis of mathematical description of the hydrological cycle has been employed since the end of the 19 th century. The form and application have remained the same through all this time, notwithstanding developments and a process of ongoing modification. The balance structure has always been based on the same assumption: that incoming amounts of water are equal to those passing out of a given area over a given time. However, choices then need to be made in line with the objective that is to be served. The mass balance, as the simplest of the mathematical models, may first need recalling here, even if it is probably well known.
Arising out of the laws of conservation of mass and energy, the water balance equation remains a numerical representation of the hydrological cycle characterising a drainage basin, and is still useful, albeit often now in forms that reflect ever-greater expansion, and methodological perfection. In classical hydrology, the terms used for the components of the water balance are used interchangeably with those applied to components or elements of the hydrological cycle. The balance for the catchment or basin of flowing waters, lakes, swamps or aquifers, including different components of the water cycle in the area under consideration, remains in close linkage with, and is very much conditioned by, various renewable sources of water, which are integrated by the processes of water cycling, whether on the surface, just below the surface, or deeper underground.
The development of hydrological balances proceeded in stages. The water cycle required dynamic and quantitative conceptualisation representing a basis for the management of water resources on different scales. It was accepted that this should be termed the water balance, and be time-related. The German geographer Keller (1980) followed Soviet hydrologist Lvovich (1969, 1974) and Mikulski (2006 in ascribing the form of the quantitative raw balance to Brückner (1862-1927), a German geographer-climatologist. The precise date and form of the equation for this raw balance of resources are not known, but can be hypothesised (after Mikulski 1998) as a 1904 innovation. The first form of the equation was simple, with atmospheric precipitation (N) = river outflow (A) + water loss (W), this being written using the original nomenclature in German as: Keller (1980) (Kaczmarek 1996) integrated with variables characterising atmospheric or soil, vegetation-related, and riparian processes.
Rates of loss or gain of water resources may vary under various anthropogenic pressures, and may head in opposite directions.
Where the balance period is markedly shorter, there is a need to take account of dynamics of water and heat in a basin that can be safely ignored when the period is an annual one.
The equation for the water balance then (after UNESCO 1971 and Lvovich 1974) 1 is: where: P is precipitation; R 1 represents initial level of retention; H is outflow; E -evaporation; and R 2 -level of final retention.
This equation assumed the full form of the developed balance (Kędziora 1995), in line with: where: P r represents precipitation in all its forms, E is evapotranspiration (field evaporation); S p surface runoff; S g groundwater outflow; S a apotamic flow (percolation), ∆R s the change in ground retention, ∆R p the change in surface retention (in rivers, lakes, or wetlands), and ∆R i the change in retention due to interception by plant cover (Fig. 1).
If water resources in a given precisely-defined area (basin) gain expression through a time function with a freely-selected time-step, then, as developed by Overmann (Soczyńska 1997) and Owens and Watson (1979), we arrive at the following 19-component version: where: P 1 constitutes precipitation measured 1 m above the ground; P 2 is the further amount of precipitation arising out of systematic measurement errors; P 3 is "horizontal" precipitation (involving rime or hoar frost and fog); P 4 is precipitation originating with the condensation of water vapour in the air as dew; H p is the surface outflow or runoff; As can be seen, the development of such an equation requires the collection of a great deal of measurement data. Should that be lacking, we resort to empirical formulae allowing for direct or indirect estimation of some of the 19 elements of the cycling of water (or processes) considered to be operating in a basin. Sometimes consideration is confined to the more important factors, sometimes even to just one of them ( Fig. 1).
As has been noted already, the dynamic hydrological balance in a natural basin can be expressed with a set of five subsystems, or even a greater number (Fig. 1), that are interlinked in the manner depicted in Equation 2. Conservation of mass and energy dictates that transformation of any component UNESCO has recommended a version from Sokolov andChapman (1971, 1974) after Sugavara, in which water-balance components must be evaluated in relation to their variability. The evaluation error of each balance element should then depend on the distribution and variance, measuring instrument accuracy and measurement frequency, subordinated to systematic and random errors.
The drainage dynamic water balance equation as written by Overmann (Soczyńska 1997 et al.) took the form: In such a complex, multi-element form, Three links involving the exchange of matter and energy have been described in theoretical terms, i.e. the atmospheric (A), the surface-related (S) and the soil/ground/plant-related (P, G). There are naturally interactions in play between all of these ( Fig. 2).
Each of the evaporation processes (or types related to cover), e.g., field evaporation, evapotranspiration, guttation (interception by plant cover), requires a separate physical and mathematical approach (Monteith 1981;Kędziora 1995;Kowalik 1995Kowalik , 2010Jaworski 2004;Gutry-Korycka 2007). Three important ways of doing that are worthy of men-  Priestley and Taylor (1972), and British experts on evaporation and evapotranspiration Penman (1956) and Monteith (1981Monteith ( , 1985. The greatest number of creative theoretical and empirical solutions were arrived at by agro-hydrologists of the Dutch school (de Wit 1958Wit , 1965Bierhizen, Slatyer 1965;Ritema 1969;Ross 1970;Ritema, Endrödi 1970;Feddes et al. 1980), whose work included the roughness of cultivated It has been shown that the amount of water conducted by a plant is a function of these processes.
Regardless of the specific biome, the total mass of a plant is proportional to the amount of water used during its growth. This is an important feature of the hydrological cycle, which Falkenmark Hoekstra (2003), Mioduszewski (2003Mioduszewski ( , 2006, Chapagain and Hoekstra (2004) in turn revealed that the production of 1 kg in dry mass of grain requires ≈ 500 L of water, whereas the production of a 1 kg of cotton needs twice as much. These ideas can be generalized to other crops, as well  (Rodda 1953;Dobson 1977).
A method such as that involving heat balance allows for an estimation of the mean rate at which water is lost through the process of evapora- In the approaches taken (and methods of calculation applied) up to now, appraisal of the processes determining levels of useable water resources include balances relating to radiation, to heat and to the active surface (i.e. the area of ground covered by vegetation, or else the open water surface). See Kędziora (1995) and Figure 3.
The common elements of the balance equations, with R N being the residue in the radiation and heat balances expressed via equations 7a -7d, are as follows: where: ↓L is long-wave radiation reaching the land surface; ↑L is long-wave radiation from the land surface; ↓K is short-wave radiation reaching the land surface; ↑K is short-wave radiation reflected off the land surface; S is the flux of sensible heat; LE the flux of latent heat; G is the flux of soil heat; E is the flux of water vapour; H is the overall runoff into a river; P is (real) atmospheric precipitation; and R N is the differential balance for radiation. The first controlling factor in the radiation balance is the albedo of the active surface, which varies through the year and during the growing season, since it depends on the physical type  Kędziora 1995) parting from them, and as entered into approximate equations (7a-7d) was applied by Kupczyk (1980) and Soczyńska (1997).
Plant canopy transpiration (E) was estimated as the summation over a three-layer calculation with the Monteith-Penman formula according to Monteith (1965) applied at each level: where: H = the available radiative energy for each layer of the forest; c p = the specific heat of air at constant pressure; E = transpiration rate; g a = canopy layer boundary conductance; g c = canopy layer stomatal conductance; δ q = specific humidity deficit; ∆' = rate of change of saturated specific humidity with temperature; λ = latent heat of vaporisation of water; ρ = density of air.
Following Landsberg (1986), radiation absorption by the forest canopy is approximated by the Beer-Lambert Law: For example, for physiological studies in young Eucalyptus stands where: I z = the radiation beneath increasing accumulation of leaf area; I o = the net radiation above the canopy; k = an extinction coefficient (taken in this case as 0.5); L i * = leaf area index of layer i.
For each of the canopy layers, stomatal conductance, g si , was calculated as: where: L i * is the leaf area index at given canopy layer; ɡ sui is the stomatal conductance of the upper leaf surface; ɡ sli is the stomatal conductance of the lower lead surface.
An interesting solution proving useful in spatial and water management and arising out of the heat and water balance is to be found in Schierbeek (1980). In a series of stud-  There is a justified need to apply methods from different disciplines, such as geochemistry, economics, biology, the social sciences, humanities, and ecology. The relationship between the rate of use of water and its quality must be considered, as well as the causes of limited-scope renewal surrounding changes in resources.
As her many studies show, Falkenmark (1983, 1984, 1989aFalkenmark et al. 1991) played a pioneering role in formulating principles and devising ways of using surface and ground waters in relation to locations of intakes and with categorisation by precise criteria.      (2014)  is found to be increasing (de Wit 1958Wit , 1965Wit , 1969Stanhill 1960 In the wake of this activity, work commenced on potential water deficits and shortages, including a classification of relative availabilities. The synthesis adopted thus far on the basis of reports from the European Environment Agency (2012a-b, 2018) points to progress achieved with access to water, a service offered to countries by the European Commission.
A good example is also found in the Rome Report of the FAO agency responsible for food security. However, it needs to be realised that the climatic and hydrological balance and other proposals put forward by Budyko (1977,1986) are too simplistic to suffice for long-term assessments, e.g., in regard to hydrological drought. In contrast, they would seem adequate to describe meteorological drought   (Table 3).  Humidity is then classified in relation to SPEI by reference to 9 intervals for CWB values, reflecting the difference between the mean corrected precipitation total (P r ), and the mean total for potential evapotranspiration (E p ), also known as indicative evapotranspiration (in mm), with:  (IPCC 2000(IPCC , 2007(IPCC , 2012(IPCC , 2014. Among those addressing such issues were Gleick (1987), Ojima (1992), Lettenmaier (1994, Kaczmarek (1996) and Gutry-Korycka (1996). They all drew attention to the crisis facing water, given assessments suggesting major changes in resources. Such findings offered both impulse and inspiration for digital models of global climate to be developed, with spatially-dispersed or clustered parameters, and a possibility of achieving more and more accurate longterm forecasts (with development scenarios for the economy generated ever-more effectively).
Thesemodels benefitted from new digital methods, multidimensional computer graphics, areal and satellite imagery of finer and finer resolution, etc. With measurement data being obtained with ever-greater precision, regional scenarios taking shape (with their "sub-scaling methods"), deterministic or stochastic drainage-basin models can be verified with respect to precipitation and outflow, and inter alia the water balance and/or climate-related aspects.
The with the consequence that they might be particularly vulnerable to changes in water cycling. As levels of solar radiation increase, and along with them the temperature and humidity of the air, there must be a reduction in the magnitude of water resources and their availability, and hence also no guarantee that water will be available at all. However, in the circumstances of a changing climate, this kind of assessment is not an easy task, because water within each area, region or basin is in constant circulation. That means that the reserve available at any given moment is actually in a constant state of flux. Amounts of water in circulation determine the size of the renewable resource.
The first measure of this quantity adopted was the long-term (multi-annual) mean obtained for total amounts of precipitation falling in given years. In contrast, the mean expressed on an areal basis has tended to involve the long-term river discharge, or else has been seen from the point of view  The 2018 report on NBS makes no mention of the potential for use of grey infrastructure and grey water. Thus, the following describes certain NBS directions and solutions for the use of water resources that enjoy that status on account of their being inspired by the laws of nature. In terms of broad scope it is green infrastructure that is being referred to, which is capable of operating in parallel, in a measurable and beneficial way, with grey infrastructure; where hydrological processes relating to the quantity and quality of water are integrated. The principal objective is to find the most appropriate linkage between grey water and green water, so that maximum benefit can be drawn from operating the system and its capacity, with costs minimised, and the number of components limited.
For an example, we may refer to a model for irrigation by means of the optimisation of efforts to achieve harmony (Čist 2008) in the operation of irrigation systems. Work by Kovalenko and Mikhaylov (2008) relates to the control of irrigation in a system, under conditions of minimised uncertainty of supply.
It needs to be added that, for example, the temporal and spatial modelling of very variable agro-hydrological processes in a drainage basin often requires 24-hour meteorological measurement data; the lack of these data precludes necessary simulation and forecasting in the service of decision-making (Kuchar 2004).
The latest NBS generate environmental, economic, and social benefits relating to the use of water resources, especially in terms of health and sanitation, as well as food, water, and energy security. These ideas promote economic growth while maintaining biological diversity, and the recovery of species at risk for extinction, leading to the protection of whole ecosystems As opportunities for NBS to be applied are sought, reference will need to be made to the fulfilment of principles set out in the UN's ing renewable resources in connection with longterm economic benefit. These curves appropriately correspond to actions taken, with one such presented in Figure 7 showing changes in an ecosystem's throughputs of matter and energy.
Considerable potential for NBS-type ideas can be found in references to regional-

CONCLUSIONS AND REMARKS
In summary, existence in the longer term will be very much supported by the integration into economies of construction, industry, spatial planning, and the management and protection of water resources whose renewability is assured by effective conservation and limitations on levels of stress.
As with the biological approach, a broad framework of designated tasks has been adopt- to be found, in order that many processes responsible for current changes may be assessed.
And thus, it is water, present in various states in all the spheres that is of priority significance!
The management of water resources in the context of urban and rural governance must limit or ameliorate negative social and environmental impacts.
Ultimately, NBS methods need to be ap- The humanitarian aspect of water resources also makes it imperative that waters are protected and limits imposed, globally, regionally, and locally. These needs reflect a predicted increase in the use of water of some 20-30% (5,500-6,000 km 3 per year) by 2030. Further growth will be a function of ongoing agricultural development to safeguard food supplies and the availability of water for use in sanitation, for drinking, and for energy generation transportation.
The priority actions and solutions relating to water thus follow the concept of recycling, reuse, restoration, recovery and risk reduction, as well as improvements in quantity and quality, and effective regional-level management where implementation is concerned. • Gartner T., Mulligan J., Schmidt R., Gunn J.