CN-Idris: An Idrisi tool for generating curve number maps and estimating direct runoff

This article presents a raster-based Geographic Information Systems (GIS) tool called CN-Idris that outputs runoff estimates from land use/land cover and hydrologic soil group maps based on the Natural Resources Conservation Service Curve Number method. The tool enables the user to select among three antecedent moisture conditions and two values of the initial abstraction (Iₐ) parameter, and it has the option to include spatial variation in rainfall input.