Thus, for each climate simulation grid point (Fig. 1c), the R-factor
was calculated based on the average between the values generated by
Eqs. 5 and 6. Having estimated the R-factor for each time slice and for
each one of the 420 points, R-factor maps were generated based on a
geostatistical approach by ordinary kriging.
In order to analyze the behavior of rainfall erosivity (EI3h) over time,
the Mann-Kendall test (Mann, 1945) was applied to statistically analyze
if there is significant trend in these data throughout the century. Furthermore,
the Precipitation Concentration Index (PCI) for MRB was
also evaluated for this purpose, since it reveals the behavior of rainfall
concentration, especially important for regions with seasonal or semiarid
climate. Its original concept was developed by Oliver (1980) in an
attempt to define the temporal variability of rainfall distribution. The
theoretical limits range from 8.3 (uniform pluvial regime) to 100, if
the rainfall is concentrated in a month (irregular pluvial regime). According
to Mello et al. (2015), the PCI is important for analysis of erosive
potential of rain, since it can characterize a more active dynamic effect
of climate change on erosive potential of rainfall, being a complementary
index. Its calculation is given by: