PREDICTING RAINFALL EROSIVITY IN HONDURAS

Iso-erodent maps can be used in soil conservation planning to identify regions with high rainfall erosive potential. This study was conducte d to determine the significance of elevation in predicting the rainfal l erosivity index (R) in addition to the average annual precipitation and to develop an iso-erodent map for Honduras. With previously calcul ated R-factor values for eight climatic stations in Honduras, a regres sion relationship was established for estimating the rainfall erosivit y index as a function of average annual precipitation and elevation wi th R(2) Of 0.972. This regression model was used to estimate the rainf all erosivity index for each of the 344 Honduran climatic stations wit hout calculated rainfall erosivity indices. Due to the limited number of data points and their geographic clustering, the best estimates of mean rainfall erosivity indices were for stations with average annual precipitation in the range from 831 to 1313 mm and elevation between 3 60 and 1080 m. A provisional iso-erodent map of Honduras at a scale 1: 1000000 was compiled in Arc/Info format, using a basemap obtained from the digital chart of the world. Iso-lines for the 95% prediction inte rvals for new rainfall erosivity indices are displayed on the map to s how the accuracy of the new estimates. Elevation was found to be highl y significant in predicting the rainfall erosivity in addition to the average annual precipitation. Data from Costa Rica, Sri Lanka, and the southeastern USA supported this finding.