Analysis of Aggressiveness Rainfall in the Far North of Chile

The far north of Chile presents characteristics of arid zones, where the rainfall it is mainly a convective origin, which leads to high intensities in a limited space and reduced time. This pattern in associated with term aggressiveness, which has been quantified through the use of indices. In the extreme north of Chile, called Norte Grande, aggressiveness has been studied small extent, but its consequences, such as mudflows in Antofagasta, Chañaral and Calama, are widely know for the multiple human deaths and economic losses. The aim of this research was to evaluate the rainfall aggressiveness in Norte Grande of Chile through the use of indices, for this it was necessary to analyze the spatial behavior of aggressiveness indices and also to apply a trend analysis to examine the temporal variability of the indices.

66 gauge stations distributed in four administrative regions of Chile were used to average seven aggressiveness indices in 30 years of study. The punctual information serves to carry out a spatial interpolation by kriging for different indices. In addition, the Mann-Kendall´s test was realized to the series of annual rainfall and on two aggressiveness indices to find a tendency to increase or decrease.

The results of the research indicated that aggressiveness has an evident spatial pattern; increase in the indices from littoral zone towards the east, where the maximums were located in the Altiplano in the extreme north of the study area. Regarding the trend analysis, only signs were observed of a decrease in aggressiveness indices in the extreme north attributable to decrease in the concentration and amount of rainfall.