Evaluation of erosivity extremes caused by precipitation in the apodi/ mossoró-RN river basin

Abstract

Identifying areas with a potential risk of environmental degradation by anthropic or natural processes is important for sustainable management of natural resources, especially in the semiarid regions of northeastern Brazil. Rain erosivity is given by the Universal Soil Loss Equation (EUPS) which relates the erosive capacity of rainfall and its ability to disin- tegrate by the impact of the particle surface. The present study aimed to evaluate the erosion index (EI 30) and to evaluate the EI 30 extremes in the Apodi/Mossoró watershed through the theory of extreme values and to associate with the rain- fall pattern of the region. For this, precipitation data from the Agência Nacional das Águas (ANA) and the Tropical Rainfall Measuring Mission (TRMM) project were used. Among several methodologies for the selection of mathema- tical models that explain the extremes of erosivity, this research used the Akaike Information Criteria (AIC) and the Schwarz Bayesian Criterion (BIC), together with the correlation assessment at EI 30 and the coefficient of rain (Rc). Thus, Felipe Guerra station presented the best results to generate the hydrological effect of the EI 30 in the basin with TRMM data. It can be concluded that TRMM data can be of great value for the estimation of the EI 30 where observa- tional data is not available. Moreover, the EI 30 follows the precipitation seasonality and was classified as moderate whose highest values occur from February to May.