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date: 27 May 2019

The Global Groundwater Revolution

Summary and Keywords

Human behavior in relation to groundwater has remained relatively unchanged from ancient times until the early 20th century. Intercepting water from springs or exploiting shallow aquifers by means of wells or qanats was common practice worldwide, but only modest quantities of groundwater were abstracted. In general, the resource was taken for granted in absence of any knowledge regarding groundwater systems and their vulnerability. During the 20th century, however, an unprecedent change started spreading globally—a change so drastic that it could be called the Global Groundwater Revolution. It did not surface simultaneously everywhere but rather encroached into different regions as waves of change, with varied timing, depending on local conditions. This Global Groundwater Revolution has three main components: (1) rapid intensification of the exploitation of groundwater, (2) fundamentally changing views on groundwater, and (3) the emergence of integrated groundwater management and governance. These three components are mostly interdependent, although their emergence and development tend to be somewhat asynchronous. The Global Groundwater Revolution marks a radical historical change in the relation between human society and groundwater. It has taken benefits produced by groundwater to an unprecedented level, but their sustainability is assured only if there is good groundwater governance.

Keywords: Global Groundwater Revolution, intensive groundwater exploitation, hydrogeological knowledge, awareness regarding groundwater, groundwater resources management, groundwater governance

Introduction

Groundwater has undoubtedly played an important role in the furtherance of human society since the dawn of time. Initially this was most likely limited to people intercepting and using water from springs and from the baseflows of streams. Over time, several techniques were developed and gradually improved to get access to stored groundwater and to bring it to the surface. Wells represent the most ubiquitous technique; they have been constructed and used since time immemorial. Dug wells in India were already being mentioned in Holy Vedic Scriptures dating from 8000 bc (Limaye, 2013) and the oldest well in the Chinese Zhejiang Province was built before 5700–7310 bc (Zaisheng & Mengxiong, 2013). Qanats appeared almost 3,000 years ago in Armenia and Iran, and spread across the Middle East and North Africa, and finally as far as China and South America (Alemohammad & Gharari, 2010; Fetter, 2004; Wulff, 1968). Other groundwater tapping techniques include drains: in some cases these were designed to exploit groundwater and elsewhere to remove excess water. While qanats and drains function via gravity, wells require an external source of energy to lift groundwater to the surface, except when artesian conditions are present. Initially, these lifting techniques were based on the muscular energy of people or animals; and besides the elementary pulley-rope-and-bucket system a variety of ingenious energy-saving devices were invented such as the shaduf, saqiyah, arhor, and handpump (Arlosoroff et al., 1987; Margat & Van der Gun, 2013). In some regions, windmills have been used as well. More recently, since the industrial revolution, the use of diesel- or electricity-powered mechanical pumps has become widespread.

For many millennia, groundwater abstraction and other human interactions with groundwater have gradually been increasing, albeit at a slow pace, in response to the water demands of the expanding population and facilitated by enhanced skills in locating and abstracting groundwater. For a long period, the level of interaction remained low, and consequently there was no significant human impact on the natural groundwater quantity and quality regimes on a global scale.

Approximately from the onset of the 20th century, however, an unprecedented change started spreading around the world—a change so drastic that it could be called the Global Groundwater Revolution. It did not surface simultaneously everywhere but rather encroached into different regions at different times, depending on local conditions. This Global Groundwater Revolution has three main components: (1) rapid intensification of the exploitation of groundwater, in particular in arid and semi-arid regions (the Silent Revolution); (2) fundamentally changing views on groundwater, resulting from the drastic increase of information and knowledge on local groundwater systems, the recognition of the multiple services and roles of groundwater, and the growing awareness of side effects and unintended impacts of human activities; and (3) the emergence and evolution of integrated groundwater management and governance. These components are mostly interdependent, although their emergence tends to be somewhat asynchronous. In the subsequent sections they will be described in some detail.

Rapid Intensification of Groundwater Abstraction: The Silent Revolution

During the 20th century, groundwater abstraction began increasing rapidly—in many countries reaching unprecedented high annual rates. Rapid intensification of groundwater abstraction became most prominent in arid and semi-arid regions, and since it resulted there mainly from the numerous personal decisions of millions of small farmers opting for groundwater as a source of irrigation water, it was named “the Silent Revolution” (Llamas & Martinez-Santos, 2005a, 2005b). The Silent Revolution began in some countries (e.g., Italy, Mexico, Spain, United States) during the first half of the 20th century and in many other countries during the latter half. But there are also countries where it started as late as the 1990s (Sri Lanka, Vietnam, much of sub-Saharan Africa) (Shah, Burke, & Villholth, 2007). More or less simultaneously with the enormous increase in groundwater abstraction for irrigation, a major growth in groundwater use for public water supply has taken place in several parts of the world. This has resulted in a significantly higher level of human dependence on groundwater in this sector, but its volumetric contribution to the global increase in groundwater abstraction is much smaller than that of irrigation water use.

How to explain this revolutionary and spectacular change in groundwater abstraction, after so many millennia of only slow increases? As suggested by Van der Gun (2012), processes of change in groundwater systems are influenced by different categories of factors: demographic and socioeconomic drivers; scientific progress and technological innovation; governance provisions such as policy, law, and finances; and physical drivers such as climate change and natural or anthropogenic hazards. In relation to the Silent Revolution all these categories of factors may play a role but in different degrees and proportions, depending on the country, region, or aquifer considered. To illustrate this, a few cases will be presented here.

Some Examples

The Great Artesian Basin

In Australia, massive groundwater withdrawal from what is currently known as the Great Artesian Basin (Figure 1) was triggered by the discovery of regional artesian conditions, in combination with locally available skills for drilling deep wells and the information acquired by regional hydrogeological investigations. The first artesian well was drilled there in 1878, which was quickly followed by many other shallow and deep artesian boreholes being drilled—initially near artesian springs at the margins of the basin, later also in the interior of the huge basin (covering 1.7 million km2). By the end of the 19th century, already around 1,000 artesian wells were flowing, with a total discharge of approximately 350 million cubic meters annually. The rate peaked in 1918 at around 730 million cubic meters per year, discharged by approximately 1,500 flowing wells. Ever since, the number of artesian boreholes has been increasing, but as a result of gradually declining artesian water levels the total discharge started decreasing gradually (Habermehl, 2006, 2018; Van der Gun, 2012), as shown in Figure 2. The tapped groundwater allowed a significant part of arid Australia to be converted into productive grazing land, which undoubtedly has produced enormous economic benefits. It took almost to the end of the 20th century before massive endeavors were made to control and stop the trend of decreasing discharge of flowing wells in the Great Artesian Basin.

The Global Groundwater RevolutionThe Global Groundwater Revolution

Figure 1. Location of the Great Artesian Basin (Habermehl, 2018).

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Figure 2. Trends in number of artesian wells and artesian groundwater outflow from the Great Artesian Basin, 1880–2000 (Habermehl, 2006).

The High Plains

The High Plains, 450,000 km2 in extent and encompassing parts of eight states in the United States (Figure 3), forms part of the Great Plains or “American Desert” as this region was called around 1890 when farmers migrated there (Brodwin, 2013). These farmers introduced commercial agriculture, which depended on irrigation. Initially, they used surface water for this purpose, but the unreliability of streamflow during dry years made them shift to groundwater irrigation, using dug wells and windmills to lift groundwater to the surface. However, groundwater development remained modest until the drought of the 1930s, which was a decade notorious for dust storms that ruined soils. This drought, together with other factors (technical advances in well drilling and pumping equipment, inexpensive energy, profitable crop prices, and available finances) triggered an acceleration in groundwater development after the 1930s. Another severe drought during the 1950s spurred groundwater irrigation development anew. This development was supported by improved pumping technology—enabling groundwater to be withdrawn also in zones with deep groundwater tables—and the development of sprinkler irrigation, which also enabled the irrigation of land with irregular or undulating topography (Gutentag et al., 1984). Annual pumping from the High Plains Aquifer for irrigation increased from 5 km3 per year in 1949 to 23 km3 per year in 1974 but did not change much during the period 1974–1995 (Konikow, 2013). The groundwater irrigated area increased rapidly after 1940 and consisted of 2.1 million acres in 1949, 13.7 million acres in 1980, 13.9 million acres in 1997, and 12.7 million acres in 2002 (McGuire, 2003; USGS Nebraska Water Science Center, n. d.). The use of groundwater has converted the High Plains from an economically marginal zone into an economically flourishing region where 30% of the irrigated agriculture in the United States is located (Steward & Allen, 2015).

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Figure 3. Location of the High Plains in the United States.

(Source: USGS).

India

Nowhere in the world did the Silent Revolution have more spectacular dimensions than in India. The lion’s share of India’s national water demands depends on the irrigation sector. Irrigation has a long history in the South Asian subcontinent, spanning at least two millennia. Great state-controlled ancient irrigation works are known to have existed, but there is much evidence that community-level cooperation in mobilizing water for flow irrigation was a prominent aspect of agrarian life in Mughal and earlier periods. Wells played an important though supplemental role in northern and western India, but groundwater irrigation was limited by laborious water-lifting techniques (Shah, 2009). The colonial period marks the adoption of a completely new irrigation ideology, focusing on creating centralized structures for constructing and managing large irrigation systems on commercial lines (Shah, 2009). After gaining independence in 1947, the planners in India continued to concentrate on surface water projects and state-controlled canal irrigation, but several severe droughts during the period 1951 through 1972 emphasized the limitations of surface water. Consequently, from approximately 1970 onward, much more attention was paid to groundwater development (Limaye, 2013). Surprisingly, not the government but the millions of small farmers scattered around the country became the key players in the subsequent boom in groundwater development. Enabled by technical innovation (in particular regarding well drilling and pumping equipment) and catalyzed by provisions created by the government (access to finances for well construction, rural electrification, low energy tariffs, scientific groundwater studies), these myriad smallholders were able to expand the gross irrigated land area in 30 years three times more than constructive imperialism had done in 150 years (Shah, 2009; Limaye, 2013). The estimated evolution of groundwater abstraction in India from 1950 to 2010 is shown in Figure 4, together with similar time series for a selected group of other countries. India’s groundwater abstraction rate in 2010 was approximately 251 km3 per year, equivalent to a quarter of the global abstraction rate and significantly higher than the abstraction rate of any other country. States with particularly intensive groundwater abstraction are Punjab, Haryana, and Uttar Pradesh, which overlie part of the huge Indo-Gangetic Plain aquifer (Garduiño et al., 2011). Shah (2009) suggested that India’s boom in groundwater abstraction is driven more by growing scarcity of farmland than by scarcity of water. In spite of current or anticipated adverse impacts of groundwater overexploitation in several parts of the country, the enormous economic and social benefits produced so far by the groundwater boom in India are indisputable (Shah, 2009).

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Figure 4. Evolution of aggregated groundwater abstraction for a number countries with intensive groundwater exploitation (Margat & Van der Gun, 2013).

Geographical Spread of the Silent Revolution

The Silent Revolution has manifested itself in many other areas around the world: most prominently in, among others, the North China Plain; the Central Valley of California; the Alluvial Basins of Arizona; the U.S. Gulf Coastal Plain; Pakistan; Mexico; Middle Eastern countries such as Iran, Saudi Arabia, Yemen, and Oman; and southern European countries such as Spain, Italy, and Greece. What these zones, aquifers, and countries have in common (with the exception of the majority of the U.S. Gulf Coastal Plain) is that they are located in the earth’s semi-arid and arid zones, where agricultural production depends on irrigation. Outside these dry climate zones, groundwater abstraction has also become more intensive during the 20th century, but the observed changes are less pronounced and not necessarily related to agriculture.

In spite of marked increases of groundwater use in other sectors, the overall geographic pattern of the Silent Revolution is inseparably connected with irrigation. Because the decisions of individual farmers on exploiting groundwater depend on the profits expected from irrigated agriculture, it follows that the Silent Revolution is market driven. Its emergence is enabled by information on the local hydrogeology and catalyzed by the availability of advanced well-drilling technology and pumps suitable for deep wells. In addition, the farmers are often supported by soft loans and energy subsidies (Llamas & Martínez-Santos, 2005b) and by several other governmental incentives or investments such as crop price regulation, rural electrification, public wells drilling projects, and subsidies for drilling, pumping equipment, or micro-irrigation (Molle & Closas, 2017). The local context therefore explains to a large extent the beginning and evolution of intensive groundwater exploitation in any particular area.

Extrapolation of Groundwater Abstraction Toward the Future

The graphical representation of numerous processes of change in the world tends to follow an S-shaped curve (logistic curve). According to such a curve the rate of change increases gradually from initially zero to a certain maximum rate and then decreases steadily until the variable considered reaches a constant final value. Does such a curve also adequately describe the change in the aggregate rate of groundwater abstraction in an area where the Silent Revolution is taking place? At first glance, and looking at Figure 4, it seems it does. Upon closer consideration, however, it has to be concluded that this type of curve may apply in some cases but not in others. Figure 2 shows a clear example of the latter: the Great Artesian Basin’s peak discharge produced by the large number of flowing wells constructed before 1918 is much higher than the mean rate of groundwater renewal, and thus the aggregate flow rate gradually declines by the aquifer system’s feedback. The peak discharge thus is not sustainable in this case. Also in many other areas the Silent Revolution has led to unsustainably high rates of groundwater abstraction. Sooner or later such abstraction rates will have to decline, either by natural feedback of the hydrogeological system or accelerated by human control. The latter may happen if reducing the groundwater abstraction is preferred for economic or environmental reasons.

Fundamentally Changing Views on Groundwater

Drastic Increase of Information and Knowledge on the Local Hydrogeological Systems

How much pre-20th-century groundwater users knew about groundwater is hard to assess. From the paucity of available indications it may be concluded that understanding was generally limited and perceptions sometimes even erroneous, although with significant variations from region to region and from person to person. Groundwater is hidden from sight and has for a long time remained a mystery for most people, perhaps with the exception of groundwater found at shallow depths. Local observations could not be interpreted in a spatially wider context (e.g., at the aquifer scale) as long as basic notions of groundwater and groundwater systems were missing.

The 20th century witnessed a spectacular improvement in information about and understanding of the local groundwater resources and hydrogeological systems in virtually every country worldwide. This could not have happened without the scientific work by a considerable number of eminent groundwater pioneers, who particularly from the mid-19th century onward produced building stones for the scientific development of hydrogeology (Walton, 1970; Narasimhan, 2009; Howden & Mather, 2013). These building stones deal, among other things, with subsurface hydraulics (flow and storage of water in porous media), subsurface hydrogeological units (identification, delineation, and characterization of aquifers, aquitards, and aquicludes), hydrogeological systems in relation to other components of the hydrological cycle (groundwater recharge, flow and discharge, groundwater levels), groundwater quality and groundwater pollution (sources and processes). Textbooks on groundwater, for instance Todd (1959), Walton (1970) and Freeze and Cherry (1980), present the most important of these building stones and show how they can be combined in the development of conceptual models and analytical frameworks. Consequently, professionals dealing with groundwater no longer had to consider the object of their activities as a black box but gained access to concepts and tools rooted in science, allowing them to develop tailor-made conceptual models at different spatial scale levels and to analyze and simulate the processes relevant for problem solving. The advances in theoretical development thus paved the way for conducting numerous hydrogeological field investigations based on science and tuned to practical needs. Initially, such investigations were usually local in scope, often with the purpose of finding a suitable location for a new well or a new wellfield, or to underpin the design of a local groundwater abstraction. Later on, many countries recognized the merits of adopting a proactive approach by exploring groundwater systems in their full spatial extent, which has led to numerous hydrogeological mapping programs covering entire countries (or parts of them) and to many hydrogeological reconnaissance or assessment studies of areas considered important. More recently, field investigations have tended to shift from providing baseline hydrogeological information to serving more specific purposes, often related to groundwater management or newly emerging issues. Monitoring change over time of hydrogeological variables has become an indispensable activity contributing to a proper understanding of the dynamics of local hydrogeological systems.

In striking contrast with the situation a century earlier, at the beginning of the 21st century groundwater was no longer a mysterious and unexplored subject, as illustrated by Margat and Van der Gun (2013). While scientific progress has enabled professionals to acquire a generic understanding of groundwater systems and relevant hydrogeological processes, myriad field investigations and desk studies have given them access to a wealth of data and information depicting area-specific hydrogeological conditions in virtually all countries worldwide and allowing local, regional, or global groundwater issues to be analyzed. Numerous hydrogeological maps are available at the global, regional, national, and subnational level (Margat & Van der Gun, 2013; Struckmeier & Margat, 1995), many of them using the methodology and legend proposed by IAH and UNESCO (Struckmeier & Margat, 1995). Reports and papers have been written on the world’s most important groundwater systems and published in scientific journals; an increasing share of these can be downloaded from the Internet. Modern groundwater information systems have been established at the national or subnational level by an increasing number of countries, and at the regional or global level by international organizations (Van der Gun, 2018).

Recognition of the Multiple Services, Functions, and Roles of Groundwater

Until about half a century ago, it was unlikely that people dealing with groundwater were familiar with its multiple services, functions and roles. For most of them, groundwater was simply a natural resource, available to be tapped to satisfy individual or collective water demands. To a smaller number of people, living in flat waterlogged areas, groundwater mainly meant excess water that should be drained in order to render and keep their area suitable for habitation, agriculture, and other forms of land use. A similar perception of groundwater as a nuisance rather than as a resource may have prevailed among those engaged in mining activities, often requiring large volumes of groundwater to be evacuated in order to draw the groundwater level to below that of mining operations. In summary, it may be assumed that people tended to focus on their own stake in groundwater and usually were not aware of any other function or service related to their local groundwater system.

Persons abstracting groundwater for everyday use were probably the first ones to be confronted with the multiple functions of groundwater and to become aware of the interdependency between these functions. In particular in water-scarce areas, the finiteness of the water resources easily leads to competition between individuals or between the different water using sectors (domestic, irrigation, and industrial use), culminating in either a conflict or an agreed compromise. In almost all countries, it was not before the mid-20th century that such competing demands were systematically recognized and considered in area-wide anticipatory and balanced planning or management approaches. Around the same time, governments and international organizations became aware that groundwater resources and their allocation could play an important role in achieving higher-level policy objectives such as combating poverty, improving health, and supporting economic development. This awareness has resulted in many targeted groundwater development programs globally and in governance provisions designed to help pursuing the abovementioned objectives. Of more recent date is the notion that groundwater systems with their relatively high resiliance to climate change (as compared to other components of the water cycle) are bound to play an important role in human adaptation to climate change (Van der Gun, 2012).

But groundwater is more than just an exploitable resource. Among textbooks on groundwater, Freeze and Cherry (1980) was the first to emphasize this. The authors explain that groundwater is also an important feature of the natural environment, as well as an integrated part of the hydrological cycle and associated processes; that it contributes to geotechnical problems such as slope instability and land subsidence; that it also plays a role in a wide variety of geological processes, among them the generation of earthquakes, the migration and accumulation of petroleum, and the genesis of certain types of ore deposits, soil types, and landforms. Although it can be observed that the provisioning services of groundwater (water supply to water-using sectors) still dominate the way groundwater is viewed in many countries, it is also true that the environmental services of groundwater, such as its contribution to wetlands and to baseflows of streams, now rank prominently on the water management agendas in an increasing number of countries.

It has also become widely known that groundwater and aquifers may offer opportunities for developing geothermal energy or for temporary storage of heat (Van der Gun & Custodio, 2018). Geothermal energy development is making use of the fact that deep groundwater is hot, as it is a carrier of geothermal energy originating deep in the earth. Depending on the local geological conditions, this hot groundwater may either escape to the surface and produce hot springs or remain trapped at a certain depth from where it can be tapped by wells and thus brought to the surface for generating power. After passing through turbines, the lower-temperature water is returned to the subsurface. Geothermal energy, considered as a renewable and comparatively clean source of energy, is still underdeveloped, but potentially it will cover more than 10% of the energy demand by 2100 (Goldstein et al., 2011). Temporary storage and subsequent recovery of heat is applied in shallow aquifers. Surplus heat is stored during low-demand periods of the year and is recovered during periods when energy demands are higher. A common application is heating of buildings during winter.

Figure 5 presents an overview of the most common services provided by groundwater systems to people. The different roles of these services are highlighted by subdividing them into four groups, as defined by the Millennium Ecosystem Assessment classification of ecosystem services (MEA, 2005): provisioning, supporting, regulatory, and cultural services.

What has been outlined above is not an exhaustive list of the services, functions, and roles of groundwater, but it illustrates the complexity of interests than have to be considered by those currently involved in groundwater management and governance. This complexity often harbors conflicts of interest and competing demands. During the 20th century, water managers in most countries have become alert to these complexities.

Awareness of Side Effects and Unintended Impacts of Human Activities

Side Effects and Unintended Impacts

Human activities related to groundwater are driven by specific objectives and intended benefits (associated with the targeted services). Groundwater abstraction, for instance, envisages using the pumped groundwater for a specific purpose and expects that this will contribute to well-being, health, economic benefit or any other goal (depending on the type of water use). Groundwater drainage activities, in turn, do not focus on using the evacuated water but rather on making land suitable for habitation and other forms of land use, or on creating favorable conditions for mining or other subsurface activities. As in the case of groundwater abstraction, this may have an intended positive impact on well-being, health, or economic conditions.

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Figure 5. Overview of important services provided by groundwater systems, grouped according to the Millennium Ecosystem Assessment classification of ecosystem services.

However, groundwater-related human activities also tend to create unintended side effects in the form of modified state variables either within the groundwater system (internal side effects) or within interlinked systems (external side effects). Similarly, human activities in physically interlinked systems (agriculture and other land-use activities; mining/oil and gas development or use of subsurface space) are producing external side effects in the form of changes in groundwater quantity or quality. All these side effects produce unintended impacts, usually adverse ones. Awareness of these side effects and unintended impacts cannot exist without knowledge of the local groundwater systems. Consequently, this awareness has been virtually absent until recent decades, and it is still limited among planners and water sector professionals in many countries. Some elaboration follows below.

Side Effects and Unintended Impacts of Groundwater Abstraction

Abstracting groundwater, drainage activities in areas with shallow water table and other human activities that remove groundwater from the subsurface inevitably modify the local hydrogeological regimes. The abstracted water is balanced by a reduction of the volume of groundwater stored and a decrease of the natural groundwater discharge, sometimes also by induced inflow of water from hydraulically connected surface water bodies. In all cases, groundwater levels will drop, and pressures inside the groundwater masses will decline accordingly.

As long as the rates of groundwater abstraction remain modest, people usually hardly notice any modification of the hydrogeological regime. However, this will no longer be the case after groundwater exploitation in a particular area has become intensive. The inhabitants of such areas witness the gradual depletion of their springs, baseflows, and flowing artesian wells and eventually see them run dry. Declining flows of artesian wells were already observed before 1920 in the Great Artesian Basin (Habermehl, 2018; Figure 2) and even earlier—at the end of the 19th century—in California, where artesian basins had enabled many artesian wells to be drilled, initially yielding an abundant flow (Narasimhan, 2009). Many artesian wells around the world have followed, and there are more to come. The fate of almost all artesian wells and of many springs is that they will eventually stop flowing. In the long run, they will become increasingly rare. Similarly, baseflows will decline in response to intensive groundwater exploitation: but how quickly and to what extent depends on topographic and hydraulic relations between the aquifer and the riverbed. In some cases, a new dynamic equilibrium is reached in the aquifer after a certain reduction of the natural groundwater discharge rate has taken place. In other cases, however, such a reduction is not enough even after natural discharge has ceased completely; thus, groundwater levels continue to decline, either until a reduction of groundwater abstraction allows a new dynamic equilibrium to be reached or until the aquifer is exhausted. This is what has been observed and still can be observed in numerous areas around the world.

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Figure 6. A flowing artesian well (Photo: Jac van der Gun).

Spectacular long-term groundwater-level declines are observed in many exploited aquifers around the world, in particular in arid and semi-arid regions. For example, groundwater levels have declined several tens of meters in zones of the Ogallala (High Plains) aquifer and the Arizona “basin and range” alluvial aquifers in the United States, the Jeffara aquifer in Libya, the North China Plain aquifer, the Sana’a Plain Tawilah Sandstone aquifer in Yemen, and alluvial aquifers in Rajastan (India). And groundwater levels have declined even more than a hundred meters in parts of the Saq aquifer in Saudi Arabia, in the karst aquifer of the Sierra de Crevillente in Spain, and in aquifers on the Spanish islands of Tenerife and Gran Canaria (Margat & Van der Gun, 2013). Gradually, groundwater specialists have become (or are becoming) aware of the side effects of intensive groundwater exploitation and also of the impacts of these side effects such as increased pumping costs, wells running dry, economic or physical exhaustion of exploitable groundwater resources, declining spring discharges and baseflows, land subsidence, and degradation of wetlands.

An important water-quality-related side effect of groundwater abstraction is the intrusion of sea water into coastal aquifers. A rather similar process is the migration of connate saline or brackish water by upconing under wells, also mainly occurring in coastal areas. Both intrusion and upconing may cause water from wells to become unsuitable for drinking and several other purposes. These phenomena have been known about for centuries, but the corresponding hydraulic mechanism was understood only after the pioneering scientific findings of Badon Ghijben (Drabbe & Badon Ghijben, 1889) and Herzberg (1901). These findings and those of later scientists provide valuable and generally used guidance for exploiting coastal aquifers prudently.

Groundwater Pollution: Predominantly an External Side Effect of Land Use and Subsurface Activities

Until at least the mid-20th century, fresh groundwater in most parts of the world was almost by definition considered to be of good quality and suitable for all uses. Was this a correct perception, or did natural groundwater contamination (notably by soluble arsenic and fluoride) and local anthropogenic groundwater pollution remain undetected, due to few groundwater samples analyzed and the limitations in laboratory programs and techniques at that time? It seems that both do apply. It is true that during more recent decades enormous progress has been made in assessing groundwater quality by expanding the number of sampling locations and by analyzing larger numbers of parameters at ever-refined detection levels. It is also true that groundwater pollution has increased exponentially during the second half of the 20th century and has resulted in unprecedent levels of groundwater contamination. The accidental detection of numerous cases of local groundwater pollution scattered over many countries has functioned as a wake-up call for groundwater and environmental professionals around the world. Awareness has grown among these professionals that having a good picture of the potential pollution sources in a particular area is key to identifying polluted groundwater.

Domestic waste and wastewater have been produced throughout history, but the quantity and diversity of domestic contaminants are currently much higher than ever, due to unprecedented population growth and changing lifestyles. Septic tanks, untreated sewerage, and sewage disposal on land have produced (and are still producing) microbiological pollution of groundwater, making it unsafe for drinking purposes. In addition, countless open dumps and poorly designed landfills have left legacies of severely polluted soils and aquifers.

Agriculture—in particular arable farming and horticultureis globally the most widespread source of groundwater pollution. It produces diffuse pollution as a result of the application of manure, fertilizers, and pesticides. A portion of these chemical substances moves from the soil in a downward direction, passes through the unsaturated zone, and finally reaches the groundwater domain. During this downward movement it is subject to different processes that lead to attenuation and reduction of the concentrations: dilution (by dispersion), sorption, ion exchange, filtration, precipitation, hydrolysis, complexation, volatilization, and biodegradation (Morris et al., 2003). Massive use of fertilizers (N, P, and K) and pesticides has rapidly emerged after the 1950s. For example, the global nitrogen fertilizer consumption shows a nine-fold increase over the period 1961–2014: from 12 million tons in 1961 to 109 million in 2014, with by far the biggest increase being in Asia (Roser & Ritchie, 2017). If the land is irrigated, then the shallow groundwater below it is enriched with the irrigation water’s chemical and microbiological compounds, and it also tends to become more mineralized because evapotranspiration causes an increased mineral concentration of the infiltrating residual irrigation water.

Industries, mining activities, oil/gas production, and geothermal energy development have seen significant expansion during the 20th century. They are producing and processing a wide range of chemical substances (organic and inorganic compounds), part of which is disposed of as waste, with the potential to pollute groundwater (Fetter, 1993; Van der Gun & Custodio, 2018). Also, the related transport and distribution activities and infrastructure (roads, railways, waterways, pipelines, petrol stations) are potential sources of groundwater pollution. Attention to these unintended side effects has emerged only in recent decades.

The same is true for other subsurface activities such as disposal or storage of hazardous waste (e.g., radioactive waste, oil field brines, CO2), injection and recovery (e.g., temporary storage of heat, short-term storage of hydrocarbons, managed aquifer recharge), nuclear testing, and construction into the underground space (Van der Gun & Custodio, 2018).

Emergence of Integrated Groundwater Management and Governance

Defining Groundwater Management and Groundwater Governance

The two main subjects discussed in the previous sections—the Silent Revolution and fundamentally changing views on groundwater—have triggered the third component of the Global Groundwater Revolution: the emergence of integrated groundwater management and governance around the world. Before describing this process, however, a few questions need to be answered: How are groundwater management and groundwater governance defined? What is the difference between the two? How are they interrelated?

A definition of groundwater management is rarely presented in the numerous scientific papers and books addressing the subject. Not even in dedicated books such as Findikakis and Sato (2011) and Jakeman et al. (2016a) can it be found. Apparently the editors and authors made the implicit assumption that the term is understood intuitively. Adopting with minor modifications a version in Margat and Van der Gun (2013), the concept can be defined as follows: Groundwater management consists of a planned program of actions aiming at pursuing maximum benefit from the local groundwater systems to the human society, in good balance with and between the objectives of meeting vital water demands, making profits, maintaining resource sustainability, allocating benefits equitably, and conserving the groundwater-related environment and ecosystems.

For groundwater governance, a term that came into fashion more recently, several definitions have been proposed (Villholth & Conti, 2018). One of these, adopted from FAO (2016), reads as follows: “Groundwater governance comprises the enabling framework and guiding principles for responsible collective action to ensure control, protection, and socially sustainable utilisation of groundwater resources and aquifer systems for the benefit of humankind and dependent ecosystems.”

Groundwater management and groundwater governance are closely related. While groundwater management is action oriented, groundwater governance focuses on the related actors, processes, and provisions (FAO, 2016; Varady et al., 2012). In practice, there is no sharp divide between the two: some activities seem to be in a diffuse transition zone between the two and are ranked under groundwater management by some authors and under groundwater governance by others.

The Forerunners: Early Groundwater Management and Governance

Long before countries started to take responsibility for managing and governing their national groundwater resources systematically, at the local level there were already scattered instances of groundwater management and governance.

The existence of springs in populated areas and the construction of qanats (the latter since 8th century bc) obviously forced local societies to come to a consensus about rights of accessing and using local groundwater. In cases of collective use this triggered the development of rules on allocation (in cases of water scarcity) and on protection and maintenance of the physical infrastructure. Such rules and their implementation are an early form of groundwater governance and management (Molle & Closas, 2017; García, Smit, & De Vries, 2018). Wells more often than springs and qanats are exclusively used by individual well owners or well users. For such private wells, management traditionally did not go beyond operating them and adjusting the technical infrastructure if required (e.g., in response to declining water levels). However, specific management and governance practices have usually been developed in cases of collective wells (collectively owned and/or used), public wells (provided by the government), or corporate wells (Molle & Closas, 2017).

Man-made drainage of flat lowlands is another groundwater management activity that has been practiced for many centuries. In The Netherlands, this started in the 9th century with converting swampy marshlands and peatlands in the lower parts of the country into polders, and later—between 1200 and 1970 ad—with the reclamation of lakes and other water-covered areas. Prominent among the governance provisions are the water authorities, which still play an important role in the country’s operational water management (NHV, 1998; Van de Ven, 1993). Similar artificially drained land is found in several other European countries: the United States, China, Pakistan, India, Mexico, and elsewhere. Most of it is agricultural land, with a total area of 167 million hectares (Feick, Siebert, & Döll, 2005).

These examples of early groundwater management have in common that they do not attempt to address all potential services and functions of the local groundwater system. Instead they are “single-issue” oriented (adequate use of given groundwater abstraction infrastructure; groundwater level control). Each case is driven by a single purpose and serves a relatively homogeneous group of stakeholders, which means that conflicts between objectives do not occur—although competition for scarce resources may exist. In addition, the spatial scale tends to be smaller than in full-fledged contemporaneous groundwater management that will be denoted here as “integrated groundwater management.”

Integrated Groundwater Management

During the second half of the 20th century many countries at one time or another reached a turning point regarding their attitude to groundwater. Dealing with groundwater was no longer merely seen as a matter of mobilizing sufficient funds and technology to exploit the resource. Triggered by observed groundwater-related problems, the awareness was growing that groundwater is a finite resource and vulnerable to pollution, salinization, and depletion; that its allocation deserves special attention, in particular in water-scarce areas; that it provides simultaneously a variety of functions and services; and that it is interacting with the environment, land use, and uses of the subsurface. Consequently, it became evident that exploiting groundwater should be accompanied by managing the corresponding groundwater systems in all their complexity. This marks the beginning of mainstreaming integrated groundwater management and governance in the water policies of countries on all continents.

Jakeman (2016b) defined integrated groundwater management as

“a structured process that promotes the coordinated management of groundwater and related resources (including conjunctive management with surface water), taking into account non-groundwater policy interactions, in order to achieve balanced economic, social, welfare and ecosystem outcomes over space and time.”

This is a rather ambitious definition. Essential elements expressed by the adjective “integrated” are coordination (apparently between different activities regarding groundwater) and a multi-objective setting. As a result, integrated groundwater management implies taking decisions that belong to the category of “wicked problems.”

An important feature of integrated groundwater management is that it extends beyond the “groundwater box” and considers the interaction of groundwater with other policy sectors. Several international organizations have developed vision and guidance on this aspect, in order to catalyze the adoption of integrated groundwater management by individual countries. For instance, the Global Water Partnership (GWP) has produced “Perspective Papers” highlighting the relationship between groundwater and land use (GWP, 2014), urbanization (GWP, 2013), and irrigated agriculture (GWP, 2012). More recently, the International Association of Hydrogeologists (IAH) produced an open-access web series entitled “Strategic Overviews,” in which well-illustrated briefs assess, for a non-specialist audience, the relation between “sustainable groundwater” and the Sustainable Development Goals of the United Nations (UN-SDGs). These Strategic Overviews (IAH, 2017) address groundwater in relation to global change, human health, ecosystem conservation, resilient cities, food security, and energy generation, respectively. The UN-SDGs do not only function as an umbrella for activities contributing to sustainable development, but they form above all an ambitious political agenda adopted by heads of state around the world.

General objectives presented in groundwater policies and in strategic groundwater management plans are translated into groundwater management tasks or “challenges” of area- or aquifer-specific operational groundwater management plans. Table 1 presents selected groundwater management challenges, as observed in different parts of the world. It also shows examples of corresponding interventions and other management measures designed to address the challenges. These measures are subdivided into three categories: the first one (technical measures) is mainly related to technical infrastructure and its operation, while the other two focus on changing human behavior, either by formal rule (regulation and law enforcement) or by encouraging desired behavior in one way or another (incentives).

Developing integrated groundwater management is a gradual process, moving from an initial state without any significant groundwater management action (pre-management stage) through a stage in which at least one groundwater management challenge is effectively addressed (initial management stage) toward an advanced management stage characterized by mature groundwater management that effectively addresses the main groundwater challenges of the area concerned in an integrated fashion (FAO, 2016). This process did not start and does not run simultaneously in all countries: some countries (especially rich countries) have already reached an advanced groundwater management stage, whereas in some other countries the local conditions did not yet permit anything beyond the pre-management stage. In many countries, however, awareness of the need to manage groundwater properly has triggered action to establish integrated groundwater management.

Contemporaneous Groundwater Governance

Progress in groundwater management is inseparable from the development of groundwater governance. For a brief description of contemporaneous groundwater governance it is convenient to focus on its four main components: (1) actors; (2) area-specific data, information, and knowledge; (3) policy and planning; and (4) legal and regulatory framework (FAO, 2016; Van der Gun & Custodio, 2018).

Actors in groundwater governance include many categories: politicians, government agencies in charge of groundwater management, persons and entities abstracting groundwater, potential groundwater polluters (i.e., everyone living or active in the area above the aquifers considered), professionals assisting groundwater management agencies, companies offering services and equipment to those who want to abstract groundwater, water authorities, and more. All of them play their role in groundwater governance, and if some of them are missing, inactive or non-cooperative, then stagnation is likely to occur. For instance, political support is indispensable to get funds allocated for groundwater management and to get dedicated legislation developed and approved; government agencies with sufficient capacity are needed to take the lead in groundwater policy development and planning and to implement the measures decided upon; and a positive attitude and cooperative behavior of local stakeholders are crucial for the feasibility and effectiveness of most groundwater management interventions.

Table 1. Selected groundwater management tasks (“challenges”) and related measures.

Groundwater management tasks (“challenges”)

Groundwater management interventions and measures (examples)

Technical measures

Regulation and law enforcement

Incentives (in addition to awareness raising and informing stakeholders)

Promoting beneficial use of groundwater

Public well drilling programs; public water supply wellfields; government operation of facilities

Licensing

Subsidies for wells, pumps and energy; rural electrification; price guarantees for agricultural products

Optimal groundwater allocation among users and uses

Allocating water from collective wells; use of swipe cards

Defining allocation rules and priorities; licensing (accordance to rules and priorities set)

Subsidies for selected categories of uses and users

Controlling the number of wells

Closing and/or backfilling illegal wells

Licensing; minimum well spacing; control of drillers

Sanctions for violating the rules

Controlling abstraction by existing wells

Allocating water from collective wells; use of swipe cards; rehabilitate leaky artesian wells

Imposing quotas (per ha or per well)

Taxes for well drilling and for groundwater abstraction

Augmenting and managing supply (including MAR and conjunctive use)

Wells, dams, and other artificial recharge works; water harvesting works

Regulations on the use of wastewater for artificial recharge

Subsidies and technical support; providing alternative supplies; technical assistance

Control of groundwater levels (for optimal land use and for protecting ecosystems and the environment)

Drains, ditches, canals, embankments, drainage wells, pumping stations (including its operation); monitoring

Minimum, maximum, and target water levels to be maintained by local water authorities; selective prohibition of groundwater pumping

Subsidies and technical assistance; sanctions for no-compliance of obligations by stakeholders

Groundwater salinization control

Skimming wells; wide-diameter wells; scavenger wells; drainage provisions in irrigated lands

Licensing (taking into account zone- and depth-specific risks of salinization)

Subsidies and technical assistance

Groundwater pollution control

Clean-up of accidental pollution sites; wastewater treatment; well head protection; monitoring potential pollution sources and groundwater quality

Wellfield protection zones; ban on the use of certain chemicals; regulations on waste and wastewater handling; and on use of manure, fertilizers, and pesticides; land-use planning (zoning); obligatory EIA for certain activities

Sanctions on polluting behavior (according to “polluter pays” principle)

Note: Groundwater management ideally should be coordinated with land-use planning and practices, environmental management, and planning of subsurface space use and the extraction of subsurface resources.

Area-specific data, information, and knowledge are essential for the adequate identification of groundwater management issues to be addressed in each particular area, for developing appropriate groundwater management policies and plans, and for assessing the effectiveness and impact of implemented groundwater management measures. Best results and continuity are most likely obtained if the related tasks are entrusted to dedicated institutions (e.g., groundwater agencies, geological surveys, or water resources institutes). The scope of the local data, information, and knowledge to be acquired goes beyond groundwater systems and includes also their socioeconomic and environmental setting and interactions (Van der Gun, 2018). Monitoring relevant time-dependent variables is a very important activity within this component, but worldwide this is often neglected or poorly performed (FAO, 2016).

Groundwater policies define groundwater-related goals that strike a balance between the interests and preferences of the diversity of stakeholders. Usually they also present an outline of the envisaged general approach to achieve these goals, including the main principles adopted. Examples of such principles are adaptive management, the Integrated Water Resources Management (IWRM) principle, the polluter-pays principle, and the precautionary principle. On the basis of a policy and information on the local context, an area-specific groundwater management plan can be developed to define the relevant local challenges and envisaged groundwater management measures (see Table 1), to guide the implementation of the latter, and to allow periodic evaluation of the groundwater management activities and their impact.

Legal and regulatory frameworks contribute to preventing or resolving conflicts on groundwater and to dealing with groundwater matters in an orderly and satisfactory manner. First of all, there is a need to define who owns locally present groundwater and who is entitled to use it. Customary practices and older laws show a wide range of views and paradigms, often with a strong link to land ownership. But worldwide there is in modern legislation a tendency to shift from legal or perceived private or community ownership to state stewardship (Burchi, 2018). The latter opens the possibility to regulate groundwater abstraction by licenses issued by the state and to levy a tax on groundwater quantities pumped. Other areas of concern for legislation and regulation include groundwater pollution, the interaction with land use, subsurface space use or mining, and transboundary aquifer management. Enforcement of regulations (often unpopular to at least part of the local stakeholders) and levying taxes and fines require a solid legal basis. The weakest point of legal and regulatory frameworks is in most countries their implementation (FAO, 2016).

Current State and Achievements of Groundwater Management and Governance

The current state of groundwater management and groundwater governance varies considerably from country to country, and even between areas within a single country. The differences are caused by differences in local contexts; these explain the main issues focused upon, the stage of groundwater management, and the type of measures implemented. Sketching a reliable and balanced worldwide picture of the current state of groundwater management and governance is difficult, since the conventional scientific literature mainly offers fragmentary and geographically scattered information that covers a limited number of aquifers, facets, and countries. The Groundwater Governance project (FAO, 2016) made an admirable attempt to broaden the available country-oriented information by organizing five regional meetings, attended by several hundreds of groundwater professionals of all continents who responded to questions on groundwater governance in their countries. Among others, the replies showed a clear correlation between the severity of identified constraints to good groundwater governance and the present stage of groundwater management (ranging from a “pre-management” stage in most of the reporting countries of sub-Saharan Africa to a predominantly “advanced” stage in the UNECE region.1 Lack of awareness and knowledge on groundwater, insufficient political commitment, lack of funds, and weak institutions were the most frequently mentioned constraints. The inventory results showed the key groundwater management issues in different countries to vary according to physical conditions, groundwater management stage, and governance constraints. For example, improving domestic water supply is a top priority in most sub-Saharan African countries but not any more in the UNECE region; groundwater use for irrigation is a primordial issue in many Asian countries; rapid urbanization is a major issue in several countries in Asia and Latin America; groundwater pollution from agricultural land-use and environmental/ecosystem protection are key issues for most countries in the UNECE region, but they are not (or only low) on the agendas of the reporting countries from Africa and the Middle East.

What has been achieved so far seems to be little to nothing in countries affected by extreme poverty, prolonged armed conflicts, or lack of stable governments. Notable achievements, however, can be observed in several other countries. For instance, the incentives provided by the government of India to encourage the use of groundwater as a source of irrigation water have evidently enhanced the welfare of the poor in rural India, although the groundwater boom threatens to create “illfare” on a comparable scale (Shah, 2009). In Australia, elaborate programs have been carried out since 1989 to stop avoidable losses of groundwater from the Great Artesian Basin (see section “The Great Artesian Basin”). To this end, uncontrolled flowing artesian wells are capped, and open-earth bore drains are replaced by polyethylene pipes; the result is that groundwater levels started recovering during the decade 2000–2010 (Habermehl, 2018). In the United States, each state has its own groundwater legislation and other groundwater governance provisions, as well as its own governance priorities. Arizona is an early adopter of a comprehensive groundwater management approach by securing water from the Colorado River for aquifer recharge and by creating active management areas in the most populated regions (Megdal et al., 2018). In Europe, several countries have already advanced groundwater governance provisions since the 1960s or 1970s, with some emphasis on groundwater pollution control and the protection of groundwater-related environment and ecosystems. In addition to this, the Water Framework Directive (WFD) of the European Union, adopted in 2000, and its Groundwater “Daughter” Directive of 2006 have obliged member states to accelerate their groundwater management efforts in order to ensure good quantitative and chemical status of their groundwater bodies by 2015 (Fried, Quevauviller, & Vargas Amelin, 2018). On different plains in Japan, land subsidence caused by groundwater abstraction has been brought under control since the 1960s by regulating groundwater exploitation and using river water to serve the needs of some of the users previously served by groundwater (Jinno & Sato, 2011).

Since the beginning of the 21st century, significant progress has also been made at the supra-national level, in particular by regional inventories of transboundary aquifers, by the UNILC Draft Articles on the Law of Transboundary Aquifers and by pilot projects on selected transboundary aquifers (Puri & Villholth, 2018). The work done on the Guaraní aquifer, shared by Argentina, Brazil, Paraguay, and Uruguay is an impressive example (Amore, 2018). Finally, groundwater governance is even expanding toward considering issues at the global level. These include not only problems triggered by predicted climate change that will change the global patterns of water endowment and water requirements, but also those related to global trade. By means of the export of “virtual water,” global trade may have a significant influence on the fate of local groundwater systems (Hoekstra, 2018).

Conclusions

During the 20th century (mainly its second half) a radical historical change has taken place in the relation between human society and groundwater. This change—referred to here as the Global Groundwater Revolution—consists of three main components:

  1. 1. rapid intensification of the exploitation of groundwater, especially in arid and semi-arid regions (the Silent Revolution);

  2. 2. fundamentally changing views on groundwater;

  3. 3. the emergence of integrated groundwater management and governance.

These three components are to a large degree interdependent, although their emergence and development tend to be somewhat asynchronous. In addition, there are also considerable differences in timing between countries.

Several factors have driven the rapid intensification of the exploitation of groundwater resources. Prominent among these factors are technical innovations (improved drilling techniques and pumps suitable for deep wells) and the development of information and knowledge on local groundwater systems. Groundwater abstraction and use have most spectacularly increased in arid and semi-arid regions, where numerous farmers seized the opportunity to expand their irrigated land and to boost their incomes by getting access to reliable groundwater resources. Because this process was mainly the result of many uncoordinated decisions and actions by individual farmers, it is referred to as the Silent Revolution. It has produced and still is producing huge benefits, but the aggregated rates of abstraction are not sustainable in many areas of intensive groundwater exploitation, as is testified by progressively declining groundwater levels. In such areas it is a major challenge to bring the abstraction rates down to a sustainable level in a timely manner and to adapt the agricultural economies smoothly to decreasing groundwater availability.

Around the globe, the views on groundwater have expanded fundamentally in several ways. In the first place, the acquisition of data and information has contributed to knowledge of the local groundwater systems and their context, which has allowed for the replacement of the previously prevailing perception of groundwater as hidden, mysterious, and unpredictable by science-based conceptual models or images. Furthermore, the exploration of local groundwater systems revealed and highlighted also the existence of the multiple services, functions, and roles of groundwater, now recognized by a steadily growing number of groundwater professionals and planners. In addition, the views have been enriched by the awareness of interactions within single groundwater systems (e.g., interference between pumping wells) and those across groundwater system boundaries, such as the reduction of spring yields and baseflows, the degradation of wetlands, or the occurrence of land subsidence caused by groundwater abstraction, or—in the opposite direction—the pollution of groundwater by different categories of land use, use of subsurface space, or mining activities. Especially during the late 20th century, the severity and the ubiquitous presence of groundwater pollution has become evident, which ranks this phenomenon—together with groundwater depletion—under the category of main global groundwater management issues.

Identification of major problems related to groundwater—such as groundwater depletion, groundwater pollution, inequitable distribution of benefits from groundwater, degradation of groundwater-related ecosystems, environmental impacts of groundwater abstraction—has created in virtually all countries around the world a sense of urgency for integrated groundwater management and governance. Consequently, groundwater management activities and groundwater governance have emerged (or are emerging) across the globe. The pace of their evolution varies, due to large differences in boundary conditions inherent to the local context. Integrated groundwater management and governance have already proven to be effective and rewarding in a number of countries, which may encourage countries that are lagging behind to persevere in their endeavors to overcome the many obstacles on their paths. For the more advanced countries there is still a long way to go, too. The increasing interwoven nature of human activities both above and below the surface demands that policies for groundwater, land use, and subsurface activities should be coordinated. In addition, new challenges have appeared at the horizon: climate change, transboundary aquifer management, and globalization.

Groundwater has come to the forefront. The Global Groundwater Revolution marks the beginning of an era in which human society derives more benefit from groundwater than ever before. Yet at the same time this society has to take on the responsibility of governing this important resource wisely, in order to keep groundwater systems and interlinked systems in good shape for future generations.

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Notes:

(1.) The UNECE region includes the countries of Europe and Central Asia, United States, Canada, and Israel.