Monthly rainfall erosivity determined from information of four meteorological stations from Nicaragua

Abstract

The estimation of soil erosion with the Revised Universal Soil Loss Equation (RUSLE) method, requires estimating the rainfall erosivity index. The aim of this study is to determine the monthly rainfall erosivity index for the meteorological stations Managua Airport, Rivas at pacific south part, Jinotega at central north part and Juigalpa at central south part of the country. Pluviographs from the stations were used to calculate the rainfall erosivity index, using the equations proposed by Wischmeier & Smith in 1978.The total kinetic energy (E) was estimated for each storm and its maximum intensity in 30 minutes of duration (I₃₀), the storm erosivity index R_t was estimated as the product of EI₃₀, and the monthly rainfall erosivity index R_mes  was estimated as the sum of all the R_t from the storms that belong to a month. The monthlies precipitations data were used to calculate the Fournier modified index IMF. It was obtained linear correlation equations from the monthly values of rainfall erosivity index, and the Fournier modified index with a coefficient of determination greater than 0.70. It was verified the performance of the correlation equations with the coefficient of determination (r²), the Percent Biass (PBIAS) and the root mean square error (RMSE), resulting those the determined correlation equations are good to estimate rainfall erosivity index at monthly scale. The equations could be used through the months May to October, when are presents the significant rainfalls in the Managua, Jinotega, Juigalpa and Rivas departments. The maximums values of the erosivity index R were presents in the periods May-June and September-October.