Erosión y desertificación.-Índices de Fournier modificado y de concentración de la precipitación, como estimadores del factor de riesgo de la erosión, en Sinaloa, México

Abstract

ABSTRACT Some of the parameters which characterize the climatic zones, identified as Hydric Régime Indices are the rainfall concentration index (ICP), and the Modified Fournier index (IFM), which allow to evaluate, in terms of the rainfall behavior, the risk of soil erosion. The conventional ICP rank of variation goes from uniforms to irregular (8 to 100%). The calculation of this index must be done for every year and then the average is the value to use. IFM considers the monthly rainfall of the most humid month of the year in relation to the other months. This index characterizes the rainfall aggressiveness, and their conventional values go from very low (0 to 60), until very high (more than 160), and mainly mean the vulnerability and risk to soil loss. It must be calculated for every year and its annual average is then used. Altogether with ICP, these indices give a very objective idea of the possible rainfall effect in soil erosion. In this work the estimation of these two indices for the Sinaloa State (NW of Mexico) is made; ICP shows a high seasonality, and IFM depends strongly on the topography. The potential consequences of soil erosion in then estimated, through conventional values of the indices.