From Watersheds to Land-Use Zones: Thailand's 1A–5B and C–E–A Classification Systems for Sustainable Land Management

<p><span>This study presents Thailand’s watershed classification system, which categorizes land into five levels (Classes 1–5), each further divided into subcategories A and B, resulting in a total of ten levels (1A–5B). The numerical classes (1–5) indicate the ecological significance of a watershed, while the alphabetical classes (A and B) reflect the fragility and slope of the land. The system is designed to preserve ecosystem integrity, mitigate environmental degradation and guide land use according to ecological suitability. In parallel, Thailand also applies a land-use zoning system (C–E–A), which delineates areas for conservation, economic activities and agricultural or community development. Integrating watershed classification with land-use zoning enables government agencies, local communities and religious institutions to clearly understand both constraints and opportunities in land management. Notably, areas classified as Watershed Class 5B are considered the most suitable for community-based development due to their relatively low environmental restrictions.</span></p>