Resumo

BEHRENDS KRAEMER, Filipe et al. Rainfall erosivity analysis for San Pedro county (Bs. As.). Cienc. suelo [online]. 2018, vol.36, n.1, pp.124-137. ISSN 1850-2067.

Water erosion is the main land degradation process over the world and affects more than 30% of the lands in the Rolling Pampa region of Argentina. The objective of this study was to analyse rainfall erosivity for the San Pedro County during 2001-2013. The individual erosivity index EI30 was significantly correlated with the daily rainfall events (y =0,1x^2,014 ;R²= 0,73, n=184). The calculated R factor was 5200 MJ mm ha^-1 h^-1 year^-1, which is consistent with estimated regional values. The 23,9% of the registered daily rainfall events and half the mean annual precipitation were considered as erosive. Summer season months showed the highest erosivity values. A close relationship was observed between the intra-annual variation of the erosivity index and the El Niño- Southern Oscillation phenomenon. Moreover, the soil cover and management factor C estimated for the Arroyo del Tala's creek using remote sensing imagery was 0,16 for fields devoted to annual crops, which was 130% higher than the same factor for livestock feeding prairies (0,07). This highlights the differential higher erosion risk particularly during the initial stage of summer crops and to a lesser extent during April. Surprisingly, the annual precipitation value was a better estimator of the R factor than the Modified Fournier Index. We consider that the obtained results contribute to the better design of sustainable management strategies for lands affected by water erosion in the study area.

Palavras-chave : precipitation; kinetic energy; maximum intensity; land degradation.

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