3. Methodologies
3.1. Coding the Soil Units:
In order to input the soil maps in the geographic information database, it was necessary to codify the
mapping units. It was found that the number of soil sub-great groups identified in the soil map of Egypt [2]
amount to 20. These units belong to three soil orders (i.e. Entisoil, Vertisols and Aridisols), classified down
to the level of sub - great group, according to USDA [5]. Coding the soil units ought to be indicative to the
soil taxonomy, properties, as well as the landscape.