11 5 Figure 2. Global annual surface air temperature anomaly relative to the pre-industrial period. The dashed line indicates the 1.5°C threshold; shaded area highlights 2023–2025. Source: Copernicus Climate Change Service (ERA5) data; authors’ elaboration. These dynamics are increasing water stress in regions with structural or seasonal scarcity and even in areas without a historical deficit of water resources. Moreover, these pressures are compounded by gaps in the very systems intended to manage them. In fact, in most countries currently experiencing, or projected to experience, water stress, weaknesses exist in water resources management. These weaknesses manifest in: i) water information, both for climate scenario modeling and for monitoring the quantity and quality of surface and groundwater resources, as well as its use for basin-level decision-making; ii) efficiency in water use, characterized by high losses and limited reuse; and iii) the timely development of conventional and nature-based water supply augmentation projects. Monitoring networks remain fragmented and uneven, with limited hydrometric and piezometric coverage often designed under assumptions of climatic stationarity, reducing their capacity to detect shifts in water availability (European Union, 2024). Continuous water-quality monitoring, QA/QC, and data interoperability are also inconsistent. Although advanced tools - including groundwater geophysics, AI-assisted inversion, environmental isotopes, Earth observation, continuous sensing, and coupled modelling-are increasingly available (Dimech et al., 2022; Mudunuru et al., 2022; Lubczynski et al., 2024), they are not yet routinely integrated into basin-scale management, leaving surface–groundwater interactions and subsurface storage dynamics insufficiently understood. Climate-scenario modelling and hydroclimatic projections are often weakly translated into actionable water management strategies (Suárez-Almiñana et al., 2020). Basin scorecards and medium-lead early-warning systems are generally absent, limiting risk-based operation and adaptive allocation. Water-use inefficiencies persist across sectors. Agriculture accounts for roughly 70% of global freshwater withdrawals (UNESCO, 2024), yet significant volumes are lost through inefficient irrigation and conveyance. Urban systems face similar challenges: in Latin America, non-revenue water averages 38%, far above efficient benchmarks of 15–25% (World Bank, 2022). At the same time, formal wastewater reuse remains limited. Although countries such as Chile and Mexico treat more than 60% of urban wastewater, systematic productive reuse
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