A new procedure to estimate the RUSLE EI30 index, based on monthly rainfall data and applied to the Algarve region, Portugal

One of the best indicators of the potential erosion asks is the rainfall-ru noff erosivity factor (R) of the revised universal soil loss equation (RUSL E). Frequently however there is not enough data available to compute the R value, and other parameters, such as the modified Fournier index (F-mod), a re used instead. But RUSLE is less effective if only the alternative proced ures exist. One of the major discrepancies between R and the alternative pa rameters is time resolution: individual storms are used to calculate R whil e monthly averages. over the year are used to calculate F-mod. In this study, a multiple linear regression (r(2) = 0.89) involving monthly EI30, monthly rainfall for days with greater than or equal to 10.0 mm and monthly number of days with rainfall greater than or equal to 10.0 mm, for the Algarve region, is presented. Twenty-seven years of monthly rainfall er osivity values were computed far the 32 standard daily-read raingauge stati ons of the Algarve region. (C) 2001 Elsevier Science B.V. All rights reserv ed.