Assessing agricultural water scarcity at the sub basin level using AWARE and water scarcity footprint in the Phetchaburi River Basin Thailand

Abstract

Water scarcity is an increasingly critical constraint on sustainable agricultural development in Thailand, where irrigation accounts for most freshwater consumption. This study applied the Available Water Remaining (AWARE) index and the Water Stress Index (WSI) to assess water scarcity risks in the Phetchaburi River Basin and quantify the Water Scarcity Footprint (WSF) of major crops at the sub-basin level under local water management scenarios. Both indicators showed consistent spatiotemporal patterns, with the Huai Mae Prachan sub-basin emerging as a critical hotspot under baseline conditions, particularly during the dry season. Incorporating the Royal Irrigation Department’s management plans substantially reduced water scarcity across most sub-basins, exhibiting the effectiveness of adaptive water allocation strategies. However, the Upper Phetchaburi sub-basin remained structurally vulnerable due to the interaction of crop composition, topography, and limited water availability. The AWARE-based WSF results indicated that rice cultivation in the Upper Phetchaburi sub-basin exerted the highest scarcity-related pressure on water resources, reaching 2,618.88 m 3 world-eq/ton under Scenario 3, reflecting WSF rather than direct water consumption. In contrast, sugarcane and cassava exhibited lower, though still notable, impacts than those in downstream areas. When normalized by economic value, the results further highlighted spatial disparities in water-use efficiency, providing strong support for crop zoning strategies aligned with SDG 6.4. Overall, the integration of AWARE and WSF offers a robust framework for identifying critical hotspots, quantitatively evaluating water management effectiveness, and guiding spatial crop planning to enhance long-term water security and resilience under increasing climate variability.