990 2. A CLIMATE-INFORMED FRAMEWORK FOR ASSESSING MINING WATER RISK Assessing potential water constraints on mineral production requires combining climate-driven water availability with deposit-level water demand. The framework integrates global climate projections, hydrological modeling of surface and groundwater resources, and process-based water demand calculations. It provides a scalable representation of water stress in mining regions. 2.1 The HyIR Global Hydrological Aggregation Framework This work introduces HyIR (HYdrological and Industrial Resilience), a global-scale hydrological aggregator developed to quantify the evolution of water resources under climate change. HyIR is implemented as an open-source Python framework and is designed to ingest climate forcings from the Coupled Model Inter-comparison Project Phase 6 (CMIP6) general circulation models (GCMs) under Shared Socioeconomic Pathways (SSPs). It represents water dynamics through three coupled components: surface water in rivers, surface water storage in lakes and reservoirs, and groundwater stored in aquifers. The framework explicitly represents hydrological processes and exchanges between these components, including runoff generation, river routing, surface storage changes, and groundwater recharge, allowing climate-driven variations in water storage and flows to be propagated consistently through the system. HyIR operates at the native spatial and temporal resolution of the climate forcings, typically on the order of 1° × 1° and monthly time steps, and produces simulations extending to 2100, subject to the length of the climate projections. The primary outputs of HyIR are spatially and temporally resolved time series of water storage volumes and storage changes for each hydrological component. In this study, the framework is applied using a single CMIP6 climate model and one Shared Socioeconomic Pathway to demonstrate the methodological capability of the approach rather than to provide probabilistic projections of future water availability. The implications of this choice and extensions to multi-model and multi-scenario configurations will be addressed later. 2.2 Climate-Informed Indicators of Extractable Water HyIR derives indicators of extractable water availability from simulated water storage and flow in surface water bodies, rivers, and aquifers. Extractable water is defined here as the volume that can be withdrawn while remaining physically sustainable under climate-driven variability, rather than total storage or flow. For lakes and reservoirs, extractable water is defined as a fixed fraction of stored volume. At each time step, yearly extractable water is set to 10% of the maximum stored volume of the previous year. This assumption ensures that, in the absence of recharge, a surface water body would persist for at least ten years, including during drought periods. Annual extractable volumes are redistributed across months using latitudedependent seasonal profiles: strongly seasonal distributions in temperate regions, inverted seasonality between hemispheres, and weak seasonality near the equator. River water availability is derived from daily river discharge and restricted to discharge above long term low-flow thresholds. For each river, a yearly moving minimum low-flow indicator is computed over a 30-day window, from which a long-term multiannual QMNA5 quantile is derived to define the low-flow threshold. Monthly extractable discharge is defined as the portion of discharge exceeding this threshold. Groundwater availability is derived from aquifer storage above a depth threshold determined from a permeability limit of 10⁻¹³ m² using an empirical depth–permeability relationship. Extractable groundwater is defined as a fraction of this accessible storage, representing a conservative 50-year long-term sustainable withdrawal rate assumption. All indicators evolve dynamically in response to climate forcing and are computed at the native spatial resolution of the driving climate model. The resulting indicators represent physically extractable water
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