Arizona Topographic Relative Moisture Index (TRMI)

Version 2025.V.1

The Topographic Relative Moisture Index (TRMI) is a terrain-based index that estimates how wet or dry a location is likely to be based on its topographic attributes. TRMI incorporates several topographic parameters that influence moisture dynamics, including slope gradient, aspect, relative elevation (or topographic position), and landscape convexity or concavity [@parker1982]. Unlike purely hydrologic models (which might require soil or rainfall data), TRMI infers relative soil moisture patterns from topography. It’s based on the idea that topography controls moisture accumulation. This raster data layer was created to assist in mapping suitability for groundwater recharge potential throughout the State of Arizona.