Adaptive agro-ecological zoning for climate-resilient land use in the Mekong delta

ABSTRACT The Vietnamese Mekong Delta is increasingly exposed to dry-season freshwater scarcity and salinity intrusion, challenging static and rice-centric land-use planning frameworks. This study aims to develop an Adaptive Agro-Ecological Zoning (AAEZ) framework that translates hydrosalinity dynamics into operational land-use guidance under climate variability. The framework integrates percentile-based salinity scenarios (P50 and P85), dry-season discharge at Kratie, functional accessibility of water infrastructure (canals, sluices, pumping stations), and land suitability into a rule-based GIS zoning algorithm. Three hydrosalinity typologies are defined using salinity magnitude and exposure duration: freshwater (<1‰ for >300 days), transitional brackish (1–4‰ for 60–150 days), and high-risk saline (>4‰ for ≥90 days). Application of the AAEZ framework reclassifies the Delta into freshwater rice zones (about 38%), shrimp–rice transition zones ( about 42%), and brackish aquaculture zones (about 17%), with approximately 3% identified as priority transition areas where current land use conflicts with hydrological constraints. Salinity simulations using MIKE 11/21 were validated against observed records (RMSE < 0.6‰). District-level zoning guidance is provided for key provinces including Ca Mau, Tra Vinh, Bac Lieu, and Long An. The AAEZ framework offers a practical decision-support tool for integrating water-driven zoning into provincial land-use planning and climate adaptation strategies.