A scoping review of dimensions, methodologies, and scales in global trends in water security (2015–2026)

Assessing water security requires integrated approaches capable of capturing its multiple dimensions, methodological perspectives, and spatial dependencies. This scoping review examines 170 publications from 2015 to 2026 to identify global trends in water security research, focusing on conceptual dimensions, indicators, methodological approaches, and spatial-scale dependency. Based on the reviewed literature and major international frameworks, water security was organized into five interconnected dimensions: availability and access, water quality, risk management and resilience, governance and ecosystems and sustainability. Results reveal a strong predominance of watershed-scale assessments, particularly for dimensions associated with biophysical and ecological processes. Methodologically, studies were grouped into six categories, with hydrological models dominating (64%), followed by statistical and climate trend analyses (11%), water security indices (8%), risk and scenario assessments (7%), socioeconomic models (6%), and ecological approaches (4%). Methodological selection showed scale dependency: hydrological models were strongly associated with watershed assessments; statistical and climate analyses and composite indexes were more transferable across scales; risk and scenario approaches gained prominence at broader scales; and socioeconomic models shifted from local stakeholder interactions toward macroeconomic dynamics. Several indicators, including water demand, water pressure, runoff, land-use change, and ecological flows, exhibited cross-dimensional linkages. Despite the multidimensional conceptualization of water security, governance and particularly ecosystems and sustainability remained comparatively underrepresented. These findings highlight the need for more integrated, coupled, and scale-sensitive methodologies capable of linking hydrological processes with socioeconomic dynamics, governance, ecosystem functioning, climate uncertainty, and compound risks to support adaptive and sustainable water management.

Water security has emerged as a central challenge for sustainable development due to the increasing pressures exerted on water resources by population growth, urbanization, socioeconomic development, land-use change, pollution, and climate change. These interacting drivers affect not only the physical availability of water but also its accessibility and quality, the exposure of societies to droughts and floods, the capacity of institutions to manage competing demands, and the functioning of water-dependent ecosystems. Consequently, water security can no longer be understood exclusively in terms of the amount of water available to satisfy human demand, but rather as a multidimensional concept encompassing interconnected environmental, socioeconomic, institutional, and risk-related components (Gain et al., 2016; Ganoulis, 2023). The growing recognition of these interdependencies has progressively shifted water-security research toward more integrated approaches capable of representing interactions between human activities and natural systems.

Among these dimensions, water quality represents one of the most critical components of water security because of its direct implications for human health. Water security is closely linked to human health, as inadequate water quality and water pollution remain major drivers of disease worldwide. Contaminated water contributes to the transmission of diarrheal diseases, skin infections, certain cancers, and a range of childhood illnesses, highlighting the importance of integrating water quality into water security assessments (Lin et al., 2022).

Despite its increasing relevance in the past decade, impulses by the United Nations from Millennium Development Goals (MDGs) to Sustainable Development Goals (SDGs), water security remains a concept without a universally accepted definition or assessment framework. International organizations have approached the concept from different but complementary perspectives. The Organization for Economic Co-operation and Development (OECD) emphasizes a risk-based perspective, focusing on the risks associated with water scarcity, inadequate water quality, hydrological extremes, and weaknesses in water governance (OECD, 2013). The Global Water Partnership (GWP) places greater emphasis on integrated water-resources management, adequate water availability for multiple uses, effective institutions, and the maintenance of healthy aquatic ecosystems (GWP, 2025). The Asian Development Bank (ADB) operationalizes water security through domestic, economic, urban, environmental, and resilience-related components, facilitating its application across different territorial contexts (ADB, 2016). UNESCO, in turn, adopts a broader sustainability perspective that connects access and availability, water quality, water-related risks, governance, and ecosystems with wider interactions among water, energy, food, and nature-based solutions. Although these frameworks differ in their conceptual emphasis, their convergence demonstrates that water security is inherently multidimensional and requires consideration of physical water resources together with societal needs, institutional capacities, risks, and ecosystem functioning (UNESCO, 2018).

The multidimensional nature of water security has led to considerable diversity in the indicators and analytical frameworks used for its assessment and is also reflected in the different methodologies used to investigate water-security challenges. The Global Water Security Index, for example, integrates indicators associated with water availability, accessibility, safety and quality, and management through normalization and multicriteria aggregation, enabling spatial comparisons of water-security conditions (Gain et al., 2016).

Hydrological models such as the Soil and Water Assessment Tool (SWAT), from Texas, United Stated of América (United States of America), have been widely applied to simulate watershed processes and evaluate changes in streamflow, runoff, groundwater recharge, evapotranspiration, and other components of the water balance (Najimi et al., 2023; Lee et al., 2024), while the Water Evaluation and Planning System (WEAP), from Massachusetts, United States of America, is frequently used to assess water supply, demand, allocation, and management alternatives (Dlamini et al., 2023). Increasingly, these tools are combined in integrated modeling frameworks in which hydrological simulations provide estimates of water supply and planning models represent sectoral demands and allocation priorities. Coupled SWAT-WEAP applications, for example, enable the simultaneous evaluation of hydrological processes, socioeconomic development, climate change, and future supply-demand imbalances (Kishiwa et al., 2018; Tran et al., 2024; Tran et al., 2024), while more complex architectures incorporating Modular three-dimensional ground-Water Flow model (MODFLOW), from Virginia, United States, extend these assessments to surface-groundwater interactions (Abbas et al., 2022).

However, water-security research extends considerably beyond hydrological simulation. Risk and scenario assessments incorporate climate projections, hazard indicators, exposure, vulnerability, and increasingly compound and cascading disturbances to explore potential future water-security conditions (Wang et al., 2024). Composite indexes synthesize multiple dimensions into standardized measures, whereas socioeconomic models examine the reciprocal relationships among water scarcity, population, economic development, agricultural production, food demand, prices, trade, and resource allocation (Vieira et al., 2020; Zare et al., 2023). Ecological approaches further expand the analytical scope by incorporating environmental flows, ecological water requirements, ecosystem health, biodiversity, resilience, and interactions between water resources and socioeconomic systems (Zhou et al., 2024).

Despite extensive research, critical gaps remain in understanding how methodological choices align with specific spatial scales and conceptual dimensions. Existing reviews have predominantly focused on specific methodological subfields (e.g., hydrological modeling) or individual spatial scales without systematically synthesizing how dimensions, indicators, and tools co-vary across territorial contexts. To address this gap, this study presents a systematic review of global water-security research published between 2015 and 2026, examining how the concept has been operationalized across different geographical contexts and analytical scales. Specifically, the review aims to (i) integrate the principal conceptual dimensions used to characterize water security and identify their associated indicators; (ii) examine how these dimensions vary according to spatial scale; (iii) classify and analyze the main methodological approaches applied in water-security research, including hydrological models, statistical and climate analyses, water security indexes, risk and scenario assessments, socioeconomic models, and ecological approaches; and (iv) evaluate the relationship between methodological selection and spatial scale. By jointly examining dimensions, indicators, methodologies, and scale dependency, this review seeks to provide an integrated perspective on current research trends and to identify methodological concentrations, complementarities, and underrepresented areas that may guide the development of more comprehensive water-security assessments.

Search strategy and PRISMA-ScR flow

This study employed a scoping literature review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) (Page, et al., 2021) guidelines to identify and analyze global trends in water security research published between 2015 and 2026. The literature search strategy was executed across major academic databases, primarily Scopus and EBSCOhost, and complemented by targeted searches on publisher platforms including Elsevier, ResearchGate, and MDPI (Water and Sustainability) to maximize the inclusion of relevant open-access literature.

Boolean search strings were developed by combining keywords with operators (AND, OR). Papers were retrieved using keywords “water security”, “water availability”, “water stress”, “water scarcity”, “floods”, “water risk”, and “water pollution”. The systematic identification, screening, eligibility assessment, and final selection workflow followed the PRISMA scoping review process, as summarized in the flow diagram (Figure 1).

Inclusion and exclusion criteria

The review process involved the identification, screening, eligibility assessment, and final selection of relevant publications following a PRISMA-ScR methodology. The literature search was conducted using EBSCOhost and Scopus as the main bibliographic databases. Complementary searches were performed through ResearchGate and within specific scientific publication platforms and journals, including Elsevier publications and journals from MDPI (Water and Sustainability). These complementary sources were used to broaden the coverage of potentially relevant open-access studies that met the established eligibility criteria.

Studies were selected according to predefined inclusion and exclusion criteria. Publications were considered eligible when they: (i) were available through open access; (ii) showed a clear thematic relationship with water security or with one or more of its associated dimensions; (iii) were published within the 2015–2026 study period; and (iv) were written in English or Spanish.

Reports published by international organizations were also considered during the review process when they provided relevant conceptual or methodological contributions to the understanding and assessment of water security. These documents were used primarily to support the development and interpretation of the integrated water security framework.

Publications were excluded when they were duplicate entries, were written in languages other than English or Spanish, or lacked direct relevance to water security dimensions or methodologies.

To promote geographical balance in the analytical corpus, a maximum of 10 publications per country was established. When more than 10 eligible studies were identified for a country, studies were selected according to three predefined criteria: (1) conceptual breadth, prioritizing studies addressing multiple water-security dimensions or providing broader conceptual coverage; (2) methodological novelty, prioritizing studies applying distinct or integrative methodological approaches; and (3) representation across spatial scales, seeking to include studies conducted at different analytical scales. These criteria were applied to obtain a conceptually and methodologically diverse representation of the eligible literature from each country rather than to characterize national research productivity.

Data extraction and analytical framework

The literature search identified 210 potentially relevant records. Before screening, 29 records were removed, including 11 duplicates and 18 records removed for other reasons, resulting in 181 records proceeding to screening. Five reports could not be retrieved, leaving 176 reports for eligibility assessment. Following eligibility assessment, six reports were excluded because they did not demonstrate sufficient relevance to the review objectives, resulting in a final corpus of 170 studies. Information from the 170 selected publications was systematically extracted and organized into an analytical database. Each study was categorized across five primary attributes: Geographic location and spatial scale: Country, regional context, and spatial scale of analysis, categorized into Local, Watershed, National, Regional, and Global.

Water security dimension: Primary dimension addressed, classified into five overarching domains based on international policy frameworks: (i) Water Availability and Access, (ii) Water Quality, (iii) Water-related Risks and Resilience, (iv) Governance, and (v) Ecosystems and Sustainability.

Methodological approach: Predominant analytical tool or model, grouped into six categories: (i) Hydrological Models, (ii) Statistical and Climate Analyses, (iii) Water Security Indexes, (iv) Risk and Scenario Assessments, (v) Socioeconomic Models, and (vi) Ecological Approaches.

Assessment indicators: Specific biophysical, socioeconomic, or institutional metrics employed.

Cross-scale transferability: Analytical capacity of the applied methods to operate across multiple spatial boundaries.

For the methodology-scale analysis, each study was assigned to a single methodological category according to its primary methodological approach. In studies using mixed or coupled modeling frameworks, classification was based on the predominant methodological approach used to address the water-security assessment. Consequently, each study was counted only once in Figure 2, even when multiple tools or models were applied.

Water security methodologies and scale dependency

The methodological approaches identified in the reviewed literature showed a clear but heterogeneous dependence on spatial scale (Figure 2), suggesting that methodological selection is influenced by the processes represented, data requirements, analytical objectives, and spatial resolution of water-security assessments.

Hydrological models exhibited the strongest scale dependency, accounting for 78% of watershed-scale methodologies, compared with 20% at local and national scales and 38% at the regional scale, with no primary applications identified globally. Their predominance at the watershed scale reflects the capacity of process-based models to represent hydrological responses to topography, soils, land use, and climate within hydrologically defined units (Shukla et al., 2023; Ware et al., 2024; Valencia et al., 2024). This scale also facilitates integration with water-allocation and planning tools (Kishiwa et al., 2018), while applications at broader scales increasingly require coupled frameworks integrating surface water, groundwater, socioeconomic dynamics, and water quality (Deng et al., 2023; Hong et al., 2024).

In contrast, statistical and climate analyses and water security indexes showed greater transferability across scales. Statistical approaches represented 20% of local, 30% of national, and 33% of global-scale methodologies, reflecting their ability to use standardized, gridded, and remotely sensed data while supporting finer-scale applications through statistical downscaling (Mital et al., 2022). Similarly, water security indexes were more prominent at national (30%) and global (11%) scales than at the watershed scale (6%), reflecting a trade-off between standardized comparability at broader scales and contextual specificity at finer scales (Gain et al., 2016).

Risk and scenario assessments were more prominent at regional (24%) and global (33%) scales, where climate projections, spatial vulnerability, and interconnected or compound risks become increasingly relevant (Wu et al., 2024; Ridgway et al., 2024). Considering the global effects of climate change may influence these studies to have a scale larger than that of a basin. Conversely, socioeconomic models were most prominent locally (40%) but extended across broader scales, shifting from stakeholder interactions, resource allocation, and benefit sharing toward aggregated relationships among water stress, economic growth, food systems, and international trade (Zhang K. et al., 2024; Kompas et al., 2024). Ecological approaches remained scarce across all scales, with watershed and regional applications addressing ecological flows, vegetation water requirements, water-storage dynamics, and ecological security, reinforcing the gap between the conceptual recognition of Ecosystems and Sustainability and its methodological operationalization (Huang et al., 2024; Sun L. et al., 2022; Zhou et al., 2024).

Methodological scale dependency is not uniform: hydrological models are strongly associated with watershed-scale analysis; statistical and climate methods and indexes are more transferable across scales; risk and scenario assessments gain prominence at broader scales; and socioeconomic models shift from local stakeholder interactions toward macroeconomic dynamics as spatial extent increases. Ecological approaches remain comparatively underrepresented.

Integrated water security framework

To establish a common analytical framework for systematic review, the conceptual approaches proposed by four major international references on water security, the Organisation for Economic Co-operation and Development (OECD), the Global Water Partnership (GWP), the Asian Development Bank (ADB), and the United Nations Educational, Scientific and Cultural Organization (UNESCO), were comparatively examined. Although these frameworks share a multidimensional understanding of water security, they differ in their primary emphasis. The OECD adopts a risk-oriented perspective, focusing on the management of water-related risks associated with scarcity, inadequate water quality, excess water, and the capacity to ensure sustainable water management (OECD, 2013). The GWP emphasizes integrated water resources management, linking reliable access to adequate water with sustainable development, human wellbeing, ecosystem protection, and resilience to water-related risks (GWP, 2025). The ADB provides a more operational and scale-oriented framework, organizing water security around interconnected domains related to households, economic activities, urban areas, environmental systems, and resilience to water-related disasters (ADB, 2016). The UNESCO adopts a broad and integrative perspective that connects water availability, quality, human wellbeing, socioeconomic development, ecosystem conservation, and protection against water-related hazards, while emphasizing the importance of governance and sustainable resource management (UNESCO, 2018).

Rather than adopting a single institutional definition, the analysis was focused on identifying conceptual similarities, recurring components, and complementary elements across these frameworks. Components related to the physical availability of water and the ability of populations and economic sectors to obtain adequate water services were grouped under “Water Availability and Access”. Aspects concerning the suitability of water for different uses and pressures associated with pollution were integrated into “Water Quality”. Components addressing scarcity, floods, droughts, climate variability, and the capacity to cope with water-related disturbances were consolidated within “Risk Management and Resilience”. Institutional arrangements, policies, planning, and management capacities were grouped under “Governance”, while elements concerning ecosystem integrity, environmental water requirements, and the long-term sustainability of water resources were incorporated into “Ecosystems and Sustainability”.

Table 1 summarizes the conceptual contributions of the four international frameworks considered in this study and their correspondence with the five integrated dimensions of water security. The comparison reveals both convergence and differences in emphasis among the frameworks. While the OECD primarily approaches water security from a risk-based perspective, the GWP emphasizes integrated water resources management and the ADB provides a more operational and sector-oriented structure. UNESCO, in turn, incorporates a broader perspective linking water availability, quality, water-related risks, governance, and ecosystem sustainability. Despite these differences, substantial conceptual overlap is observed across the frameworks, supporting their harmonization into the five dimensions adopted in this review. This integrated structure provides a common analytical basis for examining how water security has been operationalized across the studies included in the systematic review.

Table 2 shows the geographical distribution of the reviewed studies that reveal marked differences in the research coverage of the five water security dimensions. “Availability and Access” and “Risk Management and Resilience” showed the broadest geographical representation, with studies conducted across countries in Asia, Africa, Europe, Latin America, and the Middle East. In contrast, “Governance” and “Water Quality” were addressed in a smaller and more geographically concentrated set of countries, while “Ecosystems and Sustainability” exhibited the most limited geographical representation. These patterns suggest that global water security research has predominantly focused on issues related to resource availability and water-related risks, whereas governance, water quality, and ecosystem-based dimensions remain comparatively less represented in the reviewed literature. This situation may stem from a wide variety of circumstances; however, certain problems may be more significant than others in some regions, leading to the prioritization of specific lines of research.

Water security dimensions and scale dependency

The distribution of the reviewed studies revealed a clear relationship between water security dimensions and spatial scale. As can be seen in Figure 3, all five dimensions were assessed across different territorial contexts. The watershed scale was predominant, accounting for 69% of studies addressing “Availability and Access”, 74% of “Risk Management and Resilience”, 75% of “Governance”, 80% of “Water Quality”, and 88% of “Ecosystems and Sustainability”. Other spatial scales as local and national showed considerably lower representation, although their relative importance varied across dimensions, reflecting differences in the processes, indicators, and management challenges addressed. Following this, operationalization of water security is strongly scale-dependent, with watershed-level assessments providing the primary spatial framework for integrating hydrological, environmental, socioeconomic, and institutional processes. The following subsections examine how each water security dimension is operationalized across spatial scales and highlight the main variations in indicators and analytical focus.

Availability and access

“Water Availability and Access” showed scale-dependent operationalization across the reviewed studies. At the urban scale, assessments extended beyond physical availability to include infrastructure and service reliability, incorporating indicators such as resource availability, precipitation, service coverage, distribution losses, and continuity of supply (Jabari et al., 2020). At the river-basin scale, the focus shifted toward supply-demand balances and competing water uses, using variables such as water demand, delivered supply, unmet demand, and streamflow under alternative scenarios (Nivesh et al., 2023). Basin assessments also demonstrated that overall water surpluses may coexist with seasonal deficits, emphasizing the importance of temporal variability when evaluating water security (Avilés et al., 2020). At larger basin scales, the emphasis increasingly shifted toward the spatial distribution and allocation of water resources, as national-level assessments may obscure hydrological heterogeneity and disparities among individual basins (Harifidy et al., 2022).

These reveal a transition from service-oriented indicators at urban scales to supply-demand relationships at the basin scale and spatial resource distribution across larger hydrological systems, demonstrating that scale influences both indicator selection and the methodological operationalization of water availability and access.

Risk management and resilience

“Risk Management and Resilience” exhibited a strong scale-dependent pattern, shaped by the type of hazard, exposure, and system assessed. At local scales, resilience primarily reflected the capacity of water systems to maintain their functions and adapt operations to hydroclimatic variability, emphasizing monitoring, operational reliability, and adaptive management (Szewczyk et al., 2024). At the river-basin scale, assessments increasingly integrated hydrological and climate modeling to characterize drought, flood, and water-scarcity risks under future conditions. Projected changes in streamflow, for example, revealed potential extensions of dry seasons and increasing drought and flood risks (Gesualdo et al., 2019), while the use of multiple drought indices demonstrated that indicators incorporating soil-water conditions can capture impacts not fully represented by precipitation-based metrics (Zare et al., 2023).

At regional and national scales, the focus shifted toward the spatial heterogeneity of climate impacts and sectoral exposure. Climate projections across Brazil identified contrasting regional patterns of increasing dryness and extreme precipitation, emphasizing the need for geographically differentiated adaptation strategies (Tavares et al., 2023). Similarly, national-scale modeling in China showed that changes in precipitation and runoff may redistribute risks to hydropower generation across regions and river basins, extending water-related risks to interconnected economic and energy systems (Sun L. et al., 2022). As assessments incorporate longer temporal horizons, uncertainty associated with emission scenarios, climate models, hydrological parameters, and internal climate variability becomes increasingly relevant (Cai et al., 2022), while integrated surface water-groundwater and demand scenarios provide a broader basis for evaluating system resilience under simultaneous changes in water availability and demand (Abbas et al., 2022).

These results show a transition from operational reliability and adaptive management at local scales, toward hazard characterization at the river-basin scale, and spatially differentiated exposure and sectoral vulnerability at broader scales. As spatial and temporal coverage expands, climate scenarios and uncertainty become increasingly important, shifting the conceptualization of resilience from the adaptive capacity of individual water systems toward the capacity of interconnected territorial and socioeconomic systems to anticipate and respond to hydroclimatic change.

Water quality

“Water Quality” exhibited scale-dependent progression from direct assessment of water-quality status at local scales, toward spatially representative monitoring and process-based analysis of pollution at basin scales, and ultimately to vulnerability assessment and evaluation of management interventions at watershed and sub watershed scales. Thus, spatial scale influences not only the parameters and indicators selected but also the purpose of water-quality assessment, shifting from characterizing current conditions to understanding pollution processes and supporting target management responses.

At local scales, studies primarily relied on direct physicochemical monitoring and comparison with regulatory standards to characterize surface-water and groundwater conditions, contamination, seasonal variability, and suitability for human use (Vieira et al., 2020). As the spatial extent increased, monitoring approaches increasingly addressed spatial and temporal representativeness. At the river-basin scale, for example, Temporal Stability Analysis was used to identify representative monitoring sites and optimize networks for assessing broader water-quality conditions (Zhang et al., 2022).

At watershed and river-basin scales, the focus shifted toward understanding pollutant sources, transport processes, and land-use pressures. Distributed hydrological models such as SWAT were used to simulate sediment and nutrient dynamics and support non-point-source pollution management (Das et al., 2024), while integrated land-use analyses demonstrated relationships between nutrient concentrations and cultivated, constructed, and forested areas (Lei et al., 2021). Other studies extended modeling toward the evaluation of management interventions, including low-impact development techniques that simultaneously improved hydrological conditions and reduced pollutant concentrations (Han and Lee, 2024), as well as green-infrastructure scenarios designed to reduce nutrient loads and identify spatially targeted mitigation strategies (Mugisha and Sinha, 2025). Groundwater assessments further incorporated spatial vulnerability approaches to identify areas susceptible to nitrate contamination and evaluate the influence of alternative agricultural-management practices (Potrykus et al., 2026).

Governance

“Governance” exhibited a distinctive scale-dependent pattern, determined primarily by the institutional arrangements, actors, and decision-making processes operating at different territorial levels. At local and urban scales, assessments emphasized institutional responsibilities, access to information, stakeholder participation, and water-service management, with fragmented responsibilities and limited engagement identified as important governance risks (Jabari et al., 2020). Governance at this scale also incorporated decision-support tools, such as WEAP scenarios, to connect technical evidence with strategic decisions on water supply, demand management, network efficiency, and resource allocation (Bessedik et al., 2023).

At watershed scale, governance increasingly involved translating scientific and hydrological information into coordinated planning and management. Hydrological modeling provided evidence to support sustainable water-resource decisions (Alitane et al., 2022), while analyses of land-use and management changes highlighted the importance of collaboration among watershed managers, landowners, and scientists (Noreika et al., 2021). At broader regional and transboundary scales, the focus expanded toward competing sectoral demands, strategic resource allocation, and pressures extending across administrative and political boundaries, including the effects of upstream development on downstream water availability (Abdulhameed et al., 2022). Across these scales, the Governance-Policy-Science Nexus further emphasizes communication among scientists, policymakers, authorities, and stakeholders as a fundamental mechanism for translating scientific knowledge into policy and management decisions (Ganoulis, 2023).

Governance shifts from institutional coordination, participation, and service management at local scales, toward evidence-based and multi-actor planning at the watershed scale, and strategic allocation and coordination across jurisdictions at broader scales. Unlike predominant biophysical dimensions, its scale dependency is therefore expressed mainly through increasing institutional complexity, stakeholder diversity, and decision-making scope as the geographical extent of water management expands.

Ecosystems and sustainability

“Ecosystems and Sustainability” exposed a scale-dependent progression from specific ecological water requirements toward integrated assessments of socioecological sustainability. At local and river-section scales, studies focused on defining ecological flow requirements and thresholds needed to maintain ecosystem functioning while balancing competing human water uses (Zhang K. et al., 2024).

At basin scale, this perspective expanded to terrestrial ecosystems, distinguishing between minimum water requirements for ecosystem survival and optimal conditions for conservation and restoration (Huang et al., 2024). Also adopting an ecosystem-services perspective, we can find hydrological modeling used to quantify and spatially map multiple services, including groundwater recharge, dry-season flow, water storage, peak-flow attenuation, and environmental flow provision, enabling the identification of spatial hotspots of ecosystem-service supply (Ha and Bastiaanssen, 2023). Other integrated approaches combined hydrological modeling with participatory methods to connect land-use dynamics, water quantity and quality, ecosystem services, local management practices, and sociocultural water use, demonstrating the importance of incorporating both biophysical and human dimensions into ecosystem sustainability assessments (Ordoñez et al., 2023).

At broader landscape and regional scales, the focus shifted toward interactions among land-use pressures, ecosystem-service supply and demand, and coupled social-ecological systems (Yang et al., 2024). Integrated ecological-security frameworks further incorporated socioeconomic drivers, environmental pressures, ecosystem conditions, impacts, and institutional responses (Zhou et al., 2024), and ecosystem-accounting approaches linked to hydrological processes and ecosystem services with agricultural externalities to identify environmental hotspots and support spatially targeted management (Borges et al., 2026).

Scale dependency in this dimension reflects progression from ecological requirements and thresholds at finer scales, toward ecosystem functions and services at the basin scale, and ultimately to socioecological interactions, trade-offs, ecological security, and sustainability accounting at broader scales. This progression demonstrates that increasing spatial extent broadens the conceptualization of ecosystem-related water security from maintaining individual ecological functions toward understanding the interactions between ecosystems, human demands, land use, and economic activities.

Water security indicators

The indicators identified across the reviewed studies further demonstrate the multidimensional and interconnected nature of water security, as shown in Figure 4. Although classified according to the five primary dimensions, several indicators showed important cross-dimensional linkages, indicating that water security components cannot always be assessed independently.

Availability and Access indicators primarily addressed physical water availability and access to adequate services, including safe water, sanitation, renewable water resources, water demand, and water pressure. At basin and regional scales, however, availability assessments increasingly incorporated hydrological variables such as precipitation, runoff, groundwater contributions, and evapotranspiration, reflecting the need to represent water generation, storage, and redistribution in heterogeneous systems (Cheng et al., 2024; Copeland et al., 2025). Water Quality indicators focused on the condition and suitability of water resources and showed particularly close connections with ecosystem health and sustainability.

Risk Management and Resilience incorporated indicators related to droughts and floods, hydraulic vulnerability, population exposure, runoff, storage capacity, early warning systems, and contingency planning. Several of these variables extend beyond hazard characterization, as they are influenced by land use, resource management, and ecosystem conditions. Governance indicators, including management plans, institutional performance, legal frameworks, community participation, and public investment, were more dimension-specific, reflecting the institutional and financial capacities required for effective water management. Ecosystems and Sustainability indicators addressed ecological flows, ecosystem health, protected wetlands, land-use change, and environmental degradation, with land-use change emerging as particularly cross-cutting because of its influence on runoff, water availability, hydrological risks, and ecosystem functioning.

Among the indicators identified, water demand, water pressure, runoff, land-use change, and ecological flows appeared as particularly relevant cross-dimensional indicators. Their interconnections demonstrate that indicator interpretation depends on both hydrological and territorial context and reinforce the need for integrated assessment frameworks capable of capturing interactions among resource availability, risk, governance, water quality, and ecosystem sustainability.

Methodological approaches in water security

Hydrological models

Hydrological models constituted the predominant methodological approach, accounting for 108 of the 170 studies reviewed: 68 applied SWAT, 30 used WEAP, and 10 implemented coupled or combined frameworks. Distributed across 24 countries and all five water security dimensions, their applications can be grouped into four main areas: hydrological process simulation, water-resource planning and allocation, climate and land-use scenario assessment, and coupled or hybrid modeling.

The Soil and Water Assessment Tool (SWAT) and its variants are predominantly used to simulate watershed processes, including streamflow, runoff, water yield, groundwater recharge, and evapotranspiration, and assess hydrological responses to land-use and land-cover (LULC) change (Shukla et al., 2023; Ware et al., 2024). Model adaptations such as SWAT-T and SWAT-Tb further emphasized the importance of representing region-specific ecohydrological processes (Valencia et al., 2024). In contrast, the Water Evaluation and Planning System (WEAP), primarily supported water-resource planning by integrating availability with sectoral demands, infrastructure, allocation priorities, and management scenarios, including agricultural water budgeting, water-food-energy interactions, adaptation and reuse, future supply-demand balances, and allocation policies under climate change (Yaykiran et al., 2019; Yaykiran et al., 2019; Saka and Mohammady, 2024; Zare et al., 2022). These applications highlight the complementary roles of SWAT in representing watershed processes and WEAP in resource planning and allocation (Nevárez-Favela et al., 2021).

Hydrological models have also evolved into prospective tools by incorporating climate projections, emission pathways, water-demand scenarios, and future LULC changes to anticipate water-security conditions and support adaptation planning (Sone et al., 2022; Loukika et al., 2022). More integrative frameworks couple SWAT and WEAP to connect hydrological processes with sectoral demands, allocation, and transboundary pressures (Kishiwa et al., 2018; Mejdar et al., 2023), while combinations with MODFLOW, RT3D, and System Dynamics extend assessments to groundwater, contaminant transport, and socioeconomic interactions (Hong et al., 2024; Deng et al., 2023). Hydrological outputs have also been incorporated into ecosystem accounting to assess ecosystem services and agricultural externalities (Borges et al., 2026).

The evolution of hydrological modeling in water security research reflects a transition from stand-alone process simulation toward integrated, coupled, and scenario-based modeling frameworks. SWAT predominantly represents the biophysical functioning of watersheds, while WEAP emphasizes planning and supply-demand allocation; their integration with climate, land-use, groundwater, water-quality, socioeconomic, and ecological components increasingly position hydrological modeling as the biophysical core of integrated water security assessments.

Statistical and climate analyses

Statistical and climate-based approaches are primarily used to identify spatial and temporal patterns in water-security variables rather than simulate entire hydrological systems. Methods included climate-data analysis, downscaling, trend and multivariate analyses, remote sensing, and vulnerability assessments, with applications concentrated in hydroclimatic variability and water availability, climate-related risk and vulnerability, and water quality.

For water availability, statistical downscaling improved the representation of hydroclimatic variability in heterogeneous environments where coarse-resolution datasets may not capture local conditions (Mital et al., 2022). Climate projections combined with spatial and multicriteria analyses also enabled the identification of areas exposed to future climatic and land-use pressures (Campos et al., 2024), while frameworks integrating hazard, susceptibility, vulnerability, and potential losses supported spatially explicit water-security risk assessments (Holding and Allen, 2015). In water quality assessments, statistical and multivariate techniques characterized seasonal and long-term pollution patterns (Zhang et al., 2019), whereas remote sensing combined with in situ validation provided spatially distributed information on water-quality dynamics (Izurieta et al., 2023).

Water security indexes

Water security indexes integrate multiple biophysical, socioeconomic, institutional, and risk-related indicators into standardized composite measures. Their construction generally involves indicator selection, normalization, weighting, and aggregation, although their structure varies according to spatial scale, data availability, policy objectives, and context-specific water-security challenges.

At national and global scales, standardized multidimensional indexes facilitate territorial comparison, as illustrated by the Global Water Security Index (GWSI), which integrates physical and socioeconomic components within a spatial multicriteria framework (Gain et al., 2016). At local scales, indexes can incorporate locally relevant indicators and expert-based weighting to reflect specific institutional, socioeconomic, and environmental conditions (Jabari et al., 2020). Index-based approaches also support policy monitoring, although their applicability depends on the availability and continuity of monitoring and official data (Cortez-Mejía et al., 2021). Specialized metrics, such as the Green Water Scarcity Index, further complement multidimensional frameworks by quantifying specific pressures on water resources (Núñez et al., 2012).

Water security indexes translate complex conditions into comparable metrics, ranging from standardized global assessments to context-specific and specialized applications. Their methodological challenge lies in balancing comparability, contextual relevance, and data availability.

Risk and scenario assessments

Risk and scenario assessments represent a methodological transition from individual hazard characterization toward prospective frameworks that integrate hazard, exposure, vulnerability, uncertainty, and interacting disturbances. The reviewed studies primarily addressed water scarcity, droughts, floods, and compound hydroclimatic risks using drought indices, machine learning, spatial analysis, climate projections, and vulnerability frameworks.

Predictive applications combined historical observations with data-driven techniques to anticipate future hazards. The integration of the Standardized Precipitation Index (SPI), Long Short-Term Memory (LSTM) neural networks, and geospatial analysis (Taylan, 2024). More integrated frameworks incorporated hazard and potential consequences, combining meteorological, agricultural, and hydrological drought indicators with environmental, social, and economic vulnerability to assess water-scarcity risk (Thomaz et al., 2023), while climate-model ensembles and multiple drought indicators incorporated scenario and methodological uncertainty into future risk assessments (Zare et al., 2023).

Recent approaches increasingly address compound and cascading risks, recognizing that common climatic drivers may generate spatially divergent drought and flood responses within the same hydrological system (Wu et al., 2024). Similarly, sequential disturbances such as wildfire, extreme precipitation, and post-fire debris flow demonstrate how cascading impacts can propagate through river systems, affecting infrastructure, water quality, ecosystems, and water supply (Ridgway et al., 2024). These approaches reflect an evolution toward multidimensional and dynamic risk assessment, providing a stronger basis for anticipatory and resilience-oriented water management.

Socioeconomic models

Socioeconomic models extend water security assessments beyond physical water availability by representing interactions between water resources and human systems. Integrated population, economy, food and water models examine how demographic and economic trajectories, agricultural production, food demand, and trade influence future water requirements and water-food security (Kirby and Mainuddin, 2022). On national and regional scales, economy-wide models capture indirect effects through markets and international trade, demonstrating how water and heat stress can affect agricultural productivity, prices, and food security beyond the regions directly experiencing scarcity (Kompas et al., 2024). Econometric approaches complement these models by quantifying empirical relationships between water use and economic production, including differences in agricultural water productivity and irrigation efficiency (Andrade-Servín et al., 2020).

Other approaches address resource allocation and cooperation among competing users. Cooperative game-theory models evaluate how allocation and benefit-sharing mechanisms influence collective gains and incentives for cooperation (Zhang et al., 2024), while integration with hydrological planning connects socioeconomic development with resource constraints. WEAP-based nexus assessments, for example, combine population growth, agricultural expansion, climate change, and energy requirements to evaluate water-energy tradeoffs under alternative development scenarios (Chengot et al., 2024).

Socioeconomic models capture the bidirectional relationship between water security and socioeconomic development: water scarcity affects production, economic benefits, markets, trade, and food security, while demographic and economic change, consumption, and allocation decisions simultaneously reshape water demand and pressure on available resources.

Ecological approaches

Ecological approaches were the least frequently applied methodological category but broadened water security assessments by explicitly incorporating ecosystem water requirements, ecological health, and human-nature interactions. At finer scales, studies assessed ecological flows and water requirements to balance ecosystem needs with competing human uses (Zhang Y. J. et al., 2024), while vegetation-based approaches distinguished between minimum water requirements for ecosystem survival and optimal conditions for conservation and restoration (Huang et al., 2024). At broader scales, remote sensing enabled spatial assessment of relationships among water storage, ecological conditions, and climatic and anthropogenic pressures (Sun Y. et al., 2022).

More integrated approaches conceptualized water resources as components of coupled socioecological systems. Ecological-security frameworks incorporated socioeconomic drivers, environmental pressures, ecosystem conditions, and management responses (Zhou et al., 2024), while emerging eco-water security and Water, Energy, Food nexus perspectives emphasized interdependencies among water, biodiversity, ecosystem services, resilience, and other resource systems (Xia et al., 2021; Herrera-Franco et al., 2023).

Despite this methodological evolution, their limited representation reveals a gap between the conceptual recognition of Ecosystems and Sustainability as a fundamental dimension of water security and its empirical operationalization. Greater integration of ecosystem health, ecological flows, biodiversity, and ecosystem services therefore remains an important direction for developing more comprehensive water security assessments.

This review confirms that water security is inherently scale-dependent, as the dimensions, indicators, and methodologies used to assess it vary according to the spatial scale of analysis. The predominance of watershed-scale studies reflects the suitability of river basins for representing interactions among hydrology, climate, land use, and ecosystem processes, whereas national and global assessments increasingly rely on standardized indicators and composite frameworks to address broader spatial patterns (Gain et al., 2016; Shukla et al., 2023; Ware et al., 2024; UNESCO, 2020).

The predominance of hydrological models may be explained by several complementary factors. Water availability, runoff, streamflow, and climate-driven hydrological variability are among the most directly quantifiable components of water security, and watershed-based models provide established frameworks for representing these processes spatially and temporally. In addition, widely applied tools such as SWAT and WEAP have progressively expanded beyond conventional hydrological simulation to incorporate climate projections, land-use change, water demand, allocation, groundwater, and socioeconomic components (Kishiwa et al., 2018; Deng et al., 2023; Hong et al., 2024). This methodological maturity and capacity for coupling may partly explain their continued dominance compared with governance and ecosystem approaches, whose variables are often more context-dependent and less easily represented within standardized quantitative frameworks.

The comparatively limited representation of governance and ecosystems and sustainability appears to reflect challenges that extend beyond data availability and model maturity. Governance processes involve institutional arrangements, regulatory structures, stakeholder participation, power relations, and decision-making mechanisms that are highly context and scale-dependent and are therefore difficult to translate into standardized and comparable quantitative indicators (Ganoulis, 2023). Moreover, governance outcomes do not necessarily correspond to hydrological boundaries, as institutions and regulatory authorities generally operate within administrative jurisdictions, creating spatial mismatches between the units used to model water processes and those in which water-related decisions are made. Ecosystem-based assessments face a related conceptual challenge: ecological responses emerge from nonlinear interactions among hydrological processes, land-use pressures, ecological requirements, ecosystem services, and human interventions, making it difficult to represent ecosystem functioning through a limited set of water-security metrics (Ordoñez et al., 2023; Zhou et al., 2024). Consequently, the marginal representation of these dimensions may reflect not only technical constraints but also the difficulty of operationalizing institutional and socioecological processes within assessment frameworks historically structured around more readily quantifiable variables such as water availability, runoff, demand, and hydrological risk.

Several indicators, including water demand, water pressure, runoff, land-use change, and ecological flows, were found to connect multiple dimensions simultaneously, reinforcing that water security should be understood as an interconnected rather than compartmentalized concept (Ganoulis, 2023; Huang et al., 2024; Zhou et al., 2024). From an applied perspective, these cross-dimensional indicators can be jointly used to connect hydrological conditions with human pressures and ecosystem requirements. For example, practitioners can evaluate runoff and water availability against water demand, while incorporating land-use change to identify territorial pressures and ecological-flow requirements to assess potential trade-offs between human water uses and ecosystem needs. Their combined interpretation can therefore support the identification of critical pressures and the prioritization of management interventions.

An additional cross-scale challenge arises from the mismatch between hydrological and administrative boundaries. While watersheds provide natural spatial units for representing water flows, runoff, ecological processes, and upstream-downstream interactions, socioeconomic planning, regulation, investment, and decision-making generally operate within fixed administrative jurisdictions (Abdulhameed et al., 2022; Ganoulis, 2023). This mismatch becomes particularly relevant in transboundary and multi-jurisdictional basins, where hydrological impacts may propagate across territories governed by different institutional arrangements. Future integrated assessments should therefore couple hydrological models with socioeconomic and governance frameworks capable of explicitly representing administrative boundaries, jurisdiction-specific policies, stakeholder interactions, and allocation decisions (Kishiwa et al., 2018; Mejdar et al., 2023). Such coupling could allow hydrological outputs generated at watershed or sub-watershed scales to be translated into decision-relevant information for municipalities, regions, and national authorities, while also accounting for institutional interactions across shared water systems.

Future research should therefore move beyond general calls for methodological integration toward specific coupled frameworks. Promising directions identified within the reviewed literature include linking hydrological models such as SWAT with water-allocation tools such as WEAP, incorporating System Dynamics to represent socioeconomic feedbacks, integrating remote-sensing products for spatially distributed monitoring, combining hydrological modeling with participatory approaches, and linking hydrological outputs with ecosystem-service and ecosystem-accounting frameworks (Kishiwa et al., 2018; Deng et al., 2023; Ordoñez et al., 2023; Borges et al., 2026). These approaches could provide more operational pathways for incorporating socioeconomic dynamics, governance processes, ecosystem functioning, and cross-scale interactions into water-security assessments.

Key limitations of the review

This review has several limitations that should be considered when interpreting the identified global patterns. The literature search was primarily conducted through Scopus and EBSCOhost and complemented by targeted searches in selected publisher platforms and other scientific sources. Although this strategy provided broad coverage of the literature, the exclusion of other major bibliographic databases, particularly Web of Science, may have resulted in relevant studies not being captured. Consequently, the geographical and methodological distributions reported in this review should be interpreted as patterns within the literature corpus analyzed rather than as an exhaustive representation of all global water-security research.

Eligibility was restricted to publications available through open access and written in English or Spanish. These criteria facilitated consistent access and analysis of the selected studies but may have introduced both accessibility and language biases. Research published behind subscription barriers or in other languages may represent methodological approaches, governance contexts, and region-specific water-security challenges that are insufficiently captured in the present dataset. This limitation may be particularly relevant for regions where scientific and institutional knowledge is frequently disseminated in national languages or through locally accessible publication channels. Consequently, the geographical representation observed in the review may partly reflect the language eligibility criteria and should not be interpreted as a comprehensive representation of water-security research production across all regions.

The same way, the review primarily focused on peer-reviewed scientific publications, while grey literature was incorporated only selectively, particularly reports from international organizations used to support the conceptual framework. Local governmental reports, technical assessments, basin-management plans, regulatory documents, and other institutional sources were not systematically included in the analytical corpus. This limited representation of grey literature may be particularly relevant to the Governance dimension, as local and national governmental documents may contain information on institutional arrangements, regulatory implementation, stakeholder participation, and operational water-management practices that are not captured in peer-reviewed publications. Their limited inclusion may therefore have contributed to the comparatively low representation of governance-related studies and may restrict the review’s ability to capture locally specific institutional and management practices.

Although, the application of a maximum threshold of 10 publications per country was adopted as a geographical balancing criterion to limit the disproportionate influence of highly represented countries on the identification of global research patterns. When the number of eligible studies from a country exceeded this threshold, studies were prioritized according to conceptual breadth, methodological novelty, and representation across spatial scales. Although this procedure increased the geographical diversity of the analytical corpus, it may also have introduced selection bias by excluding eligible studies from countries with larger scientific outputs and favoring studies with broader conceptual coverage or methodological novelty. Consequently, the synthesized global trends may underrepresent more recurrent or conventional methodological approaches within highly productive countries, while comparatively increasing the influence of conceptually or methodologically distinctive studies. Country-level frequencies should therefore not be interpreted as measures of national research productivity. The findings are instead intended to characterize broader patterns in water-security dimensions, indicators, methodologies, and spatial scales within a geographically balanced corpus of literature, and regional-level interpretation is more appropriate for discussing geographical research patterns.

This systematic review supports the organization of water security into five interconnected dimensions: water availability and access, water quality, risk management and resilience, governance, and ecosystems and sustainability. The findings suggest water security as a multidimensional concept in which biophysical, socioeconomic, institutional, risk-related, and ecological processes interact, requiring assessment frameworks capable of capturing their interdependencies.

Spatial scale emerged as a fundamental determinant of how water security is conceptualized and operationalized. The watershed was the predominant analytical scale, particularly for biophysical dimensions, where interactions among climate, hydrology, land use, water availability, water quality, and ecosystems can be explicitly represented. However, scale dependency extends beyond geographical extent: local assessments emphasize services, infrastructure, institutions, and stakeholder interactions; watershed studies focus on hydrological and ecological processes; and broader scales increasingly incorporate aggregated indicators, climate scenarios, socioeconomic dynamics, and interconnected risks.

Water security dimensions cannot be assessed independently. Variables such as water demand, water pressure, runoff, land-use change, and ecological flows showed cross-dimensional relevance, connecting resource availability with risk, water quality, governance, and ecosystem sustainability. Indicator frameworks should therefore move beyond rigid dimensional classifications toward integrated structures capable of representing interactions and feedback among water-security components.

One limitation in water security research is the imbalance between conceptual and methodological treatment. Availability and access and water-related risks and resilience were the most widely represented dimensions, whereas governance and particularly ecosystems and sustainability remained underrepresented. This highlights a gap between the widespread conceptual recognition of water security as a multidimensional challenge and its empirical operationalization, which remains disproportionately centered on hydrological processes and physical water availability. Comprehensive research into water security is necessary.

Although water security is a global challenge, its assessment remains inherently territorial and context specific. Future research should strengthen the integration of governance and ecosystem components, cross-dimensional indicators, socioeconomic dynamics, climate uncertainty, and compound risks through increasingly coupled methodologies. Bridging these conceptual, methodological, and spatial dimensions will be essential for advancing water security assessments capable of supporting adaptive and sustainable water management under growing climatic and socioeconomic pressures.