…from the ESRI Map Book, Volume 24…
“Some of the feature characteristics of potential aquifer recharge zones are soil permeability values and steepness of slope. In other words, water will tend to sink into the ground more readily in areas where the soil is more permeable and the slope is level or nearly level.
“Soil permeability values and slope steepness values can be represented as layers in a GIS for further analysis. A new layer (Potential Aquifer Recharge Zones) can be created by combining the soil permeability values with the slope steepness values.
“Courtesy of the California Department of Water Resources.”