A Poly-Shock Sentinel-Node Framework for Scenario-Based Assessment of Water-Scarcity Risk in the Transboundary Talas River Basin Using GIS-WEAP

Transboundary river basins in Central Asia are exposed to interacting reductions in available inflow, increasing water demand and infrastructure losses. This study develops a poly-shock sentinel-node framework for the scenario-based assessment of water-scarcity risk in the Kazakhstan part of the transboundary Talas River Basin. The methodology combines GIS-based spatial analysis, WEAP water-allocation modeling, nine scenarios for 2026–2030, and the Poly-Shock Sentinel Risk Score (PS-SRS) for four water-demand nodes. Here, poly-shock denotes a deliberately constructed combination of hydrological, demand-related, infrastructure, and operational stressors. The model outputs are interpreted as conditional scenario-based stress tests rather than deterministic forecasts. Under the specified assumptions, annual unmet demand in 2030 ranges from 5.98 million m3 yr−1 in Reference to 56.90 million m3 yr−1 in TP2. Under the assumed Policy parameter package, no simulated unmet demand occurs, while TP4 reduces unmet demand from 52.01 to 20.33 million m3 yr−1 relative to TP3. Sentinel identity is scenario-dependent: PS Asa is the first system-level node under Reference and Growth, whereas Zhambyl SDPP is the earliest chronological system-level detector under the Climate Scenario, Adaptation, and TP1–TP4. PS Asa remains the first irrigation-season agricultural sentinel across all scenarios in which agricultural risk occurs. The proposed PS-SRS is interpreted as a case-specific node-level diagnostic that should be considered jointly with annual unmet demand and the first threshold-crossing month.