Reviewing Water Wars and Water Weaponisation Literatures: Is There an Unnoticed Link?

Abstract

The prediction made by former Vice President of the World Bank, Ismail Serageldin, that the wars of the 21st century will be about water, remains on the international political agenda. Yet, there is enough evidence corroborating that water wars have not occurred in the past and that there are sufficient mechanisms in place to prevent them in the future. Simultaneously, domestic water violent conflicts have been taking place, usually as immediate reactions to localised disputes. More importantly, water weaponisation has been gaining visibility during violent conflicts, violating international humanitarian law without any consequences so far. This paper reviews the water wars and water weaponisation literatures, arguing that there is an under-researched link between these two literatures and practices. This review suggests that the water weaponisation discourse and practice may facilitate the context for the water wars prophecy to become true.

1. Introduction

In 1995, the then Vice President of the World Bank, Ismail Serageldin, stated that as the wars of the 20th century had been about oil, the wars of the 21st century will be about water [1,2]. Since then, this prediction has been repeated in the news and on social media. It has become embedded in the political discourse of different decision-makers and has almost achieved the status of a La Palice truth, being understood as self-evident. The water wars literature has evolved into two, albeit interrelated directions: identifying water hotspots that gather the conditions considered essential for a water war to occur [3,4] and understanding the settings in which water wars have not occurred [5]. Although water weaponisation may seem an intrinsic element of water wars, its research has evolved somewhat in a dissociated manner [6,7,8]. After all, water wars follow a very specific typology, that is, violent conflict waged between/among riparian States over water access and utilisation. Water weaponisation includes these cases of water wars but presents a much broader map of the circumstances under which water may be weaponised, including civil wars, civil unrest, terrorism, domestic riots, among others. This article derives from the exponential increase in water weaponisation since the turn of the century (around a 500% increase in the weaponisation cases officially registered). Most of the water wars literature is focused on access to water as a natural good, and some structural infrastructures such as dams, whereas water weaponisation (although including water and dams) also includes water, sanitation and hygiene (WASH) infrastructures.

Although recognising that the literatures on water wars and water weaponisation present ample space for articulation, they have developed separately for the most part. This article argues that better attention should be given to the potential relationship between water weaponisation practices and the water wars debate. For this effect, the next section presents a literature review on water wars and water weaponisation. The third section lays out the article’s reasoning, discussing the potential interconnections between water weaponisation practices and water wars narratives. The final section identifies future avenues for research to contribute to a better understanding of water weaponisation and water wars.

2. Literature Review

2.1. Water Wars

When water wars are discussed, the focus is on the 310 transboundary rivers that cross two or more countries. This involves 150 States and their basins (territory delineated by a river, its affluents, and the extension of the remaining surface water that flows into that river and its affluents) where around 52% of the world population live, and 60% of freshwater is stored [9]. Although most of the research has been on transboundary river basins, one cannot dismiss transboundary lakes as well as aquifers [10,11]. Also, wars are understood to be armed conflicts between two or more sovereign States which reach at least 1000 battle-related deaths in a specific calendar year [12]. The literature reflects a sort of debate on the future occurrence of water wars, because although there is a clear group of scholars highlighting there has never been a water war, and therefore analysing the underlying dynamics that have prevented water wars in the past, these can be fostered to avoid water wars in the future [5,13,14,15]. Further, some scholars, often being the same authors [4,16,17], have invested in identifying transboundary water relationship hotspots that may evolve into violent conflicts and water wars. These two lines of research, although not excluding one another, create an idea of a debate about water wars (Figure 1).

The argument for predicting water wars is based on the concept of water scarcity and on the fact that with existing and increasing water scarcity, riparian States will have less water to share, triggering conflicts, and eventually water wars. This argument is based on a zero-sum understanding of inter-State relations (Figure 1). Water is finite. Water is scarce. Water is an economic good. As an internationally shared river, lake, or aquifer has less water available (either because riparian demand has increased or its freshwater supply has diminished), the riparian States’ relations will escalate, until water wars occur. There are several studies addressing water scarcity and how it can be measured [18,19,20,21,22,23] with several indicators of varying complexity being calculated. Most of these indicators “have rarely been applied beyond the research groups where they were developed” [24] (p. 547). Until the 2000s, water scarcity indicators were very basic.

The Water Stress Index (Falkenmark Indicator) (

Table 1. Water scarcity definitions.

Falkenmark Indicator		Water Criticality Ratio
Annual Renewable Freshwater *	Level of Water Stress		Withdrawal to Availability Ratio
>1700	Occasional or local	Low or no	<20%
≥ 1000 < 1700	Regular	Medium	≥ 20% < 40%
≥ 500 < 1000	Chronic	High	≥ 40% < 80%
<500	Absolute	Extremely high	≥80%

Note: * m³/per person/per year. Source: Adapted from [25,26] (p. 331).

) compares the estimated quantity of water available in a territory with the number of inhabitants of that same territory [25]. If a person has access to 1700 m³ to 1000 m³ of water per year, they live in a regular water stress situation which already conditions their means of living. If a person has access to 1000 m³ to 500 m³ of water per year, then they live in a chronic water scarcity context and their lives are directly affected by the lack of water. Finally, if a person has access to less than 500 m³ of water per year, they live in an absolute scarcity situation and their means of living are already severely undermined [25]. The Water Criticality Ratio (Water Vulnerability Index) (Table 1) compares the estimated quantity of water available in a territory with the estimated quantity of water extracted (Water Criticality Ratio) [26]. The great advantage of this indicator is that it focuses on the water use practices in a territory [26,27,28]. A territory in which water extraction in relation to the estimated quantity of water available is above 40% is characterised by high water stress, and extremely high water stress if above 80% [26]. On the other end, a territory that extracts less than 20% of the estimated quantity of water available is characterised by low water stress [26].

There are several variations of these indicators, but these two remain the most used [24,29]. Still, the remaining indicators consider various aspects that are also important when studying water scarcity, such as measuring physical and economic water scarcity where the economic ability to use water is considered [23], measuring water security at the household and community levels, and engaging with the concept of water poverty [30]. All these indicators, when compared among riparian States, provide grounding for increased demands for water by each riparian State and for discussions on the priorities of water use.

The results of this line of research have included the identification of Basins at Risk (Figure 2) by Wolf’s team at Oregon State University working on the Transboundary Freshwater Diplomacy Database [31], a risk assessment for the Emergency Response Coordination Centre of the Directorate-General for European Civil Protection and Humanitarian Aid Operations (DG-ECHO) [32], and water hotspots by the World Meteorological Organisation [33], among others. All these visualisations provide a prediction of possible international violent conflicts due to water access and use among riparian States.

The Basins at Risk project identified various river basins that should be monitored due the conflictual relations among riparian States that might escalate into war (Figure 2). Among these are the Ganges-Brahamputra-Meghna, and the Mekong River basins in Asia, as well as several in South Africa (i.e., Zambezi, Limpopo, Okavango, Kunene, Orange, and Incomati). River basins such as the Nile, Tigris/Euphrates, Jordan, and the Aral Sea are identified as being under dispute or undergoing negotiations at the beginning of the 21st century.

This work is a result of an extensive investigation on water wars in the past, which concluded that there have been no water wars fought, at least back to 2500 BC [34,35]. The oldest interaction that referred to violence between riparian States, related to water access and use, is from 2500 BC when two Sumerian City-States (Lagash and Umma) engaged in a dispute over water and irrigation which led to a century of conflict [34,36]. This finding constitutes the cornerstone of the line of research that argues that water wars are not self-evident and can be avoided (Figure 1). No author denies the fact that water has had, and continues to have, a significant role in various contexts of international armed conflicts and wars; however, they have investigated the reasons underlying the absence of water wars.

This line of research includes the investigation of the type of riparian interactions and analyses their hostile or cooperative nature [3,37,38]. In a 2003 study, Yoffe et al. [3] focused on water riparian interactions between 1948 and 1999. The results showed that there had been more water riparian interactions characterised by cooperation than by hostility [3]. Of all these registered interactions, around 45% were about quantitative water sharing and 19% on infrastructure issues [3]. Paradoxically, the main reasons for extreme hostile conflict (100%) and cooperation (59%) are very similar, as follows: water quantity (90%) and infrastructure (10%), and water quantity (29%) and hydroelectric production (30%), respectively [3]. This study considered various factors to explain the differing intensities of hostile conflict and cooperation. The overall conclusions of this line of research, as Wolf stated in 2003, were that “Arid climates harbored no more conflicts than humid climates, and international cooperation actually increased during droughts. (…) Democracies engaged in water conflicts as often as autocracies, rich countries as poor countries, densely populated countries as often as sparsely populated ones, and large countries as often as small ones” [35] (p. 117 emphasis in the original).

From these results, this line of research has evolved to better understand why water conflicts or disputes have not evolved into hostile or violent conflicts including war. The overall conclusion is that in the transboundary river basins where hostile or violent conflicts have not occurred, there were, or were created, institutions to regulate, manage, dilute, and address those conflicts [35]. Thus, the argument for predicting the non-occurrence of water wars is an institutional one. Creating water institutions among riparian States provides space for confidence building, increasing the predictability and stability of their water relations. In fact, the Lagash-Umma dispute resulted in a treaty that ended the dispute over the River Tigris’ water [34,39] (p. 5). According to the Food and Agriculture Organisation (FAO) of the United Nations Organisation, over 3600 treaties related to transboundary water have been signed between 805 AC and 1984 [39] (p. 6). Most of these treaties addressed issues of navigation and border delimitation [39]. Figure 3 provides a visualisation of how most transboundary river basins have some sort of agreement signed among their riparian States, such as the Nile River Basin in Africa, and the Great Lakes Basin in North America. Still, some transboundary river basins have no type of agreement in effect, such as the Orinoco River Basin in South America, with a recent Judgement from the International Court of Justice (2023).

More important, perhaps, is the fact that an institutional factor was not the only aspect that was statistically relevant [35]. In fact, a dynamic analysis showed that the crucial factor explaining the conflictual/cooperative intensity of diverging transboundary water relations were the institutions that had the capacity to absorb and manage sudden and drastic changes [35] (p. 118).

It also needs to be added that transboundary water interactions are now also framed by two United Nations Conventions: Convention on the Protection and Use of Transboundary Watercourses and International Lakes (1992), the Water Convention, and the Convention on the Law of Non-navigational Uses of International Watercourses (1997), the Watercourses Convention (for a comparison, see [40]). The Water Convention was initially negotiated among the United Nations Economic Commission for Europe (UNECE) members as a pan-European water governance framework. But, after an amendment in 2013, any United Nations member can join the Convention [41].

In conclusion, the literature on water wars reflects a sort of debate, in the sense that there is an argument, based on water scarcity, that reiterates the predictability of water wars. There is another argument, that does not preclude the former one completely, that water wars have not occurred and can be avoided through resilient riparian institutions.

2.2. Water Weaponisation

Even though water wars are not an international reality [42], water and armed conflict still share a complex relationship, particularly related to the use of water as a weapon of war. Despite being an ancient warfare practice, water as a weapon of war is a relatively novel concept, intimately associated with environmental terrorism and hydro-terrorism [43,44,45]. As a practice, water weaponisation can occur in multiple ways, namely by directly targeting water-related infrastructure, such as dams, dykes, and WASH facilities, and by contaminating water as a natural good through the use of poison or disease-causing agents [46]. Although poisoning water sources was a common practice in ancient times, at present, its actual use remains rare in violent conflicts and was prohibited after the Second World War with the Biological Weapons Convention [47,48]. Therefore, the attack, destruction and capture of water-related infrastructure represents the most frequent use of water weaponisation during armed conflicts [49].

Originally introduced by Gleick in the 1990s, the term ‘water as a weapon’ describes the use of water and its systems as tools or weapons in violent conflicts [6,50]. This author identifies other categories of water-related violence, as illustrated in Figure 4, including water as a trigger or root cause of violent conflict (i.e., when violence is triggered by economic or physical barriers to access water, or by water scarcity) and as a casualty during armed conflicts (i.e., when water becomes either a deliberate target or an unintended casualty of violence) [6,49,51].

For instance, the cut-off of the Mekorot water supply to Gaza in 2023 by the Israeli government is an exemplary case of the use of water as a weapon of war, whereas the destruction of a water well in Somalia in 2013, and the violent clash over water sharing in India in 2002, are all instances of water as a casualty and as a trigger, respectively [49]. Gleick [6] broadly defines water as a weapon by portraying it as a direct weapon and an indirect causality of armed conflict. This conceptualisation lacks depth, excluding important dimensions and meanings essential for a more comprehensive understanding of water as a weapon of war [52].

In recent years, this concept has gathered significant academic attention, often linked to the reported upsurge of cases where water has been used as a weapon since the 1990s [53]. Prominent scholars have offered different definitions of this practice, each framing water as a weapon in its multiple typologies, as represented in Figure 4 [6,7,8,54,55,56]. This concept has increasingly been labelled as water weaponisation, a term first coined by King [7] and later adopted by other researchers, including von Lossow [55], Daoudy [8], and Grech-Madin [56]. Although Gleick [6,53] does not employ this term, the examples described throughout this review were identified in his water conflict chronology and conform with water weaponisation and its various dimensions advanced by King [7], von Lossow [55], Daoudy [8], and Grech-Madin [56]. Therefore, the cases outlined in the water conflict chronology fall into the water weaponisation category and demonstrate an increase in the use of this practice as a tool of warfare [49].

King [7] (pp. 155–158) proposes a revised water weaponisation framework by considering other crucial categories, namely strategic, tactical, and unintentional types of water weaponisation, and the use of water as an instrument of psychological terrorism and extortion or incentivisation (Figure 4). This in-depth conceptualisation highlights the underlying meanings and motives behind the practice. As such, King embraces a security-focused approach that acknowledges the perpetrator’s deliberate use of water weaponisation to advance political and military advantages [7,54,57].

Whereas strategic weaponisation involves using water to virtually or effectively exert control over critical territories or facilities to achieve sovereignty, as well as leveraging it as a resource to finance activities (e.g., in 2012, Syrian rebels captured the Tishrin dam located on the Euphrates River), the use of water as an instrument of extortion or incentivisation seeks to establish legitimacy as a governing authority or to provide incentives for support from the ‘occupied’ population (e.g., in 2014, the Islamic State granted water discounts to Sunni residents who returned to Mosul after its initial conquest) [7] (pp. 156–158) [49]. Both dimensions dialogue with von Lossow’s [55] strategic political motive since they advance the belligerents’ political objectives, power, and authority (Figure 4). Moreover, King’s [7] strategic weaponisation is aligned with Grech-Madin’s [56] strategic weaponisation since in both conceptualisations, water is weaponised to achieve higher-order goals like a belligerent’s victory.

Conversely, tactical weaponisation is closest to Gleick’s concept because it relates to the employment of water to directly or immediately support military operations, or against targets of strictly military value (e.g., in 2022, Russian forces cut off water access in Sievierodonetsk, Ukraine) [7] (p. 157), [49,57] (p. 68). Grech-Madin [56] also dialogues with King’s [7] tactical weaponisation by arguing that the use of water weaponisation as a tactical objective assists with the accomplishment of low-order goals in conflict, thus supporting military operations. As demonstrated in Figure 4, unintentional weaponisation aligns with Gleick’s definition of water as a casualty, because it is concerned with the collateral damage caused by water weaponisation to civilians and the environment (e.g., in 2023, Israeli settlers and militias destroyed water systems in the West Bank triggering a water shortage) [7] (p. 158) [49]. Meanwhile, the use of water as an instrument of psychological terrorism aims to provoke fear among civilians by restricting access to, or contaminating water supplies (e.g., in 2016, Iraqi oil pipelines were destroyed and used to contaminate the Tigris River and the water supplies of downstream communities) [7] (p. 158), [49]. King’s framing of this concept emphasises the interconnectedness of the aforementioned dimensions, presenting a richer and denser interpretation compared to Gleick’s [52].

Inspired by King [7], von Lossow [55] underscores water’s strategic political, tactical military, and psychological value, arguing that these motives prompt water weaponisation. Tactical military and psychological goals include actions such as flooding an opponent’s territory or cutting off its water supplies to instil fear [55] (p. 85). Grech-Madin [56] also builds on King’s [7] conceptual work, offering the most up-to-date definition of water weaponisation that classifies this practice based on type (i.e., deprivation and inundation) and objective (i.e., strategic and tactical). Deprivation entails the reduction, complete denial, or degradation of water (e.g., by poisoning and water blockade). Inundation corresponds to the swift release of a substantial volume of water by demolishing storage structures or opening floodgates. Like von Lossow [55], Grech-Madin [56] (p. 90) argues that water weaponisation can be strategic when it serves to accomplish long-term goals during violent conflicts (e.g., victory or the enemy’s surrender), and can also be tactical, aiming to achieve immediate goals during wars, notably by undermining the opponent’s ability to fight through the cut-off of water supplies.

In turn, Daoudy’s [8] water weaponisation conceptualisation incorporates Gleick’s [6] and King’s [7] approach (Figure 4). By centring her analysis on the control of water and its historical dynamics, Daoudy [8] (p. 1351) considers water as both an offensive and defensive weapon by categorising the use of water weaponisation for domination and legitimacy (i.e., when water is used as a symbol of identity and a means to consolidate power by state and non-state actors in their interactions with the population); as a military target and goal (i.e., when water infrastructure is attacked, damaged or destroyed, and captured); as a military tool by cutting off water, intentional flooding, and defensive fortification (i.e., when a state or non-state actor instrumentalises water infrastructure already under their control or seized by them to intimidate populations, force concessions from adversaries, or directly advance tactical objectives during military operations); and as a tool of cooperation (i.e., delivery or negation of basic infrastructure-generated services). Daoudy [8] challenges the strictly militaristic view of water weaponisation developed by King [7] and Gleick [6] by showing how water control is not only about domination and coercion, but also about cooperation and negotiation. As such, Daoudy [8] brings forward an innovative and holistic understanding of water weaponisation.

The key distinction between these water weaponisation frameworks is that while Gleick [6], King [7], and Daoudy [8] frame the use of this weapon as both a deliberate and accidental practice of warfare, von Lossow [55] and Grech-Madin [56] interpret it exclusively as an intentional practice, always instrumentalised with a specific purpose. These definitions consider water as a strategic, tactical, and psychological weapon. On the one hand, Daoudy [8], King [7], von Lossow [55], and Grech-Madin [56] recognise the strategic use of water weaponisation for the accomplishment of political goals (e.g., power consolidation, legitimacy, sovereignty, and control of important territories). On the other hand, water weaponisation is tactically instrumentalised to support military operations according to all definitions [6,7,8,55,56]. The psychological dimension of this mode of warfare is only present in Daoudy’s [8], King’s [7], and von Lossow’s [55] conceptualisations as a means to terrorise civilians. Overall, these definitions prove that water is a powerful tool in armed conflicts. Nevertheless, the concept of water weaponisation is still underdeveloped [56].

As a practice, water weaponisation is a growing global issue that has been gaining international visibility. Presently, several actors at the international level have been addressing this warfare practice, especially in the context of the Israeli-Palestinian conflict’s most recent violent confrontations. For instance, the United Nations and its organs, including the Security Council and the Human Rights Council, the Special Rapporteur on the situation of human rights in the Palestinian territories (i.e., Francesca Albanese), and the Special Rapporteur on the human rights to safe drinking water and sanitation (i.e., Pedro Arrojo-Agudo); international tribunals, such as the International Criminal Court; and non-governmental organisations, such as Human Rights Watch, Oxfam, and Euro-Med Human Rights Monitor have been drawing attention to the use of water weaponisation by Israel [58,59,60,61,62,63].

Albeit this fledgling tendency of using water weaponisation in violent conflicts, Grech-Madin [56] maintains that the water taboo (comprising a set of principles and norms that prohibit such practices) has been accepted, adopted, and thus strengthened by the international community. As a result, the author suggests that States are increasingly refraining from using water weaponisation in international violent conflicts and becoming the de facto custodians of water [56].

3. Discussion

Although the water wars and water weaponisation literatures do not dialogue directly, Grech-Madin [56] has recently argued the existence of a water taboo regarding water weaponisation in international conflicts. The author’s focus is not the link between water weaponisation and water wars, but it does contribute to the argument that water wars are not an expected future occurrence. Her analysis of the emergence, adoption, and internalisation of the water taboo norm contributes to the existing institutional framework regarding transboundary water governance, i.e., the existence of a transboundary water governance regime that influences the behaviour of States [64,65]. The analysis of the literature on water wars, which argues that these are not necessarily going to occur in the near future, renders visible this transboundary water governance regime. Krasner’s definition of an international regime is adopted here, that is, understanding international regimes as implicit or explicit “principles, norms, rules and decision-making procedures around which actor expectations converge in a given issue-area” [64] (p. 185).

Consequently, the international regime on transboundary water governance is based on the principle of riparian solidarity and equality. This principle is rendered operational through the exercise of limited sovereignty and territorial integrity. This principle establishes that States cannot fully exercise their power of exclusion [66] (p. 5). In other words, riparian States, namely upstream countries, cannot use all the water flowing through its territory, depriving downstream countries from its access or use. This international regime includes three issue-specific norms: (a) only riparian States have rights over their internationally shared water; (b) there is a ‘natural right’ to water of the downstream States; and (c) there is an international water weaponisation taboo. In effect, this water weaponisation taboo is both a norm, weighing morally on riparian States, and a rule included in international humanitarian law. Two other rules have become part of international water Conventions: equitable and reasonable utilisation among riparian States, and an obligation not to cause significant harm. Finally, decision-making procedures are usually included in each agreement/treaty with specific provisions or, alternatively, addressed at the International Court of Justice, if needs be.

This international regime on transboundary water governance shapes the behaviour of riparian States and prescribes future water interactions with a clear emphasis on using peaceful means for addressing conflicts. It should be noted that the principle of limited sovereignty and territorial integrity is sustained by practice and jurisprudence across river basin settings of rules [67]. The norms render visible practices among riparian States and is partially derived from international water treaties’ analysis [67]. The rules have initially reflected practice, and then after being formally included in treaties and conventions, have become prescriptions on how riparian States should behave regarding their shared waters governance. This regime has emerged with these components during the post-World War II period and has stayed strong.

However, since the start of the 21st century, the use of water weaponisation has exponentially increased, intensifying the violent dynamics of both international and intrastate armed conflicts (e.g., the Russian-Ukrainian war, the Israeli-Palestinian conflict, and the Syrian and Yemeni civil wars). Between 2000 and 2023, there were 998 recorded instances of water weaponisation, compared with just 160 cases documented during the 20th century (1900–1999), according to the water conflict chronology [49]. The data suggests that water has been progressively instrumentalised as a strategic weapon by state and non-state actors, specifically during violent conflicts. Consequently, the augmented use of water weaponisation suggests the potential for this practice to be normalised in armed conflicts, serving as a means for actors to advance their political and military objectives. Grech-Madin does draw attention to the fact that in some cases, one may witness a “low-intensity weaponisation” where water weaponisation is less visible but occurs, and, on the other hand, “outside the scope of international conflict, the water taboo’s influence is limited” and that “it reaches only weakly to nonstate actors” [56] (p. 120).

These dynamics hold the potential to trigger a mimicry effect. Successful cases of water weaponisation may set a precedent for actors to adopt this practice to counterbalance or retaliate against their opponents, including States in international conflicts. Such replication can escalate cycles of violence, with water and its infrastructure becoming more frequent targets, thereby weakening international norms that prohibit water weaponisation (i.e., the water taboo) and potentially eroding them over time. Low-intensity water weaponisation may increase through this mimicry effect, questioning the mechanisms set in place that prevent water wars.

In other words, the increased practice of weaponising water may contribute to further exacerbate ongoing violent conflicts. This is not to say that water weaponisation cannot be the sole factor driving the emergence of violent conflicts around water. However, this review has focused on water weaponisation during violent conflicts. The aim is to grasp if the acceptance of water weaponisation practices within ongoing violent conflicts may contribute to a higher likelihood of water wars occurring.

As a result, further research is required to examine the relationship between the discourse and practice surrounding water weaponisation, and the discourse and practice associated with the absence of water wars. Future research on these dynamics needs to address the framing of practices on water weaponisation and its impact on the water wars narratives, focusing on norm degeneration and international regimes’ resilience.