Abstract:
Mauritius is a typical tropical volcanic island with a raised interior where extreme
rainfall events generate the bulk of the erosivity. Intra-event characteristics of the 120 highest
erosive events at six selected locations between 2004 and 2008 were analysed to provide the
first detailed intra-storm data for a tropical island environment. On Mauritius, spatial variation
is evident in the characteristics of the extreme erosive rainfall recorded at the stations, with a
noticeable increase in rainfall depth, duration, kinetic energy and erosivity of extreme events
with altitude. Extreme events in the raised interior (central plateau) show a high variability in
peak intensity over time as well as a higher percentage of events with the greatest intensities
in the latter part of the event. Intra-event distribution of rainfall in the interior of the island shows
that rainfall has a higher potential to exceed infiltration rates as well as the ability to generate
high peak runoff rates and substantial soil loss. The study suggests that even though the
within-event rainfall characteristics is complex it has implications for soil erosion risk, and that
in tropical island environments the within-storm distribution of rainfall must be incorporated
in soil loss modelling.
