An improved methodology for erosion hazard mapping. Part I: the technique

A methodology using a simple factorial scoring procedure for erosion hazard was derived in Zimbabwe in the early 1970s. Basing the new procedure on African conditions, limited data availability and coverage at a sub-continental scale, the SLEMSA (Soil Loss Estimation Model for Southern Africa) framework is shown as a useful tool in designing a suitable methodology. The abstraction of the variables - average slope, kinetic energy of rainfall, vegetal cover and an index of erodibility - is described and it is shown how they can be combined through a set of design graphs taken from the Zimbabwe Highveld version of the SLEMSA framework. Hazard is expressed in "Erosion Hazard Units' and not t/ha.