This wetness indicator (WI) is a means of measuring drainage or drainage potential in a landscape, identifying areas where water will either pool or runoff will slow significantly. The process identifies where elevation changes are less than surrounding areas and where flow routes may be somewhat inhibited. WI areas are exclusive of permanent water bodies and wetlands but may provide significant storage and contribution to these areas. This model should not be confused with the Total Wetness Index (TWI) in that it is predicated on deriving two variables from the DEM – Elevation variation and Aspect variation.
The model was tested with DEMs ranging from 6m to 100m in spatial resolution in gently rolling (eastern Alabama) and mountainous (Grand Canyon, AZ) terrains and with a DSM with a spatial resolution of 6". The DSM was over a re-forested area and demonstrated that the model was not applicable to this data set. Tests on bare earth DEMs indicated that the model could detect collection spots and areas that are more likely to hold moisture. The model overestimated Most Probable Wet Areas at 6 meter resolution and under estimated Most Probable Wet Areas at 100 m resolution.
|Bare Earth DEM||Results at 6 m resolution|
|Results at 10 m resolution||Results at 30 m resolution|
|Results at 60 m resolution||Results at 100 m resolution|