The events of natural disasters have received much attention in recent years due to their
magnitude and intensity, as well as the effect they have had on the population. The
urban population is one of the most affected, especially the one that occupies
inappropriate areas within the cities, like slopes, floodplain areas, areas without
adequate drainage, among others. One of the most recurrent events in urban areas and
that are in evidence in the State of Pará are the erosive processes. And it is in the Pará
context, more specifically in the urban territory of the city of Rondon do Pará
(mesoregion southeast Paraense), that this work was developed, in order to generate
information about these events for the public power and for the resident population, that
has been suffering with the consequence of these disasters. For this, initially, the
behavior of the rain and its effects on the erosions in the region was evaluated, through
the analysis of the Provisional Normal generated for the place, based on data from the
CMORPH satellites, the Hydrological Balance and the analysis of a study of case of
events registered in the city. Subsequently, through the calculation and analysis of rain
erosivity (R) from 1999 to 2015 and with projections for 2035, its return period and
probability of occurrence, it was searched to identify which period of the year and in
which years the loss due to erosion is most likely. Based on the analysis of the
distribution and behavior of rainfall in the region, it was observed, through provisional
normal, that the hydrological year starts in October with the rainy season and ends in
September with the aim of drought, being the month of March the wettest and August
the less rainy. The hydrological balance showed surplus water in the months from
January to April and water deficiency from June to November, with replacement from
December with the return of the rains. The cases of erosion presented annual
distribution similar to the distribution of precipitation, indicating its great influence on
them. Individual analysis of cases showed that erosion may be due as much
precipitation occurred on the day of the event as accumulated in the five days prior to
the event, the latter being the most common case. Regarding the analysis of erosivity, it
was observed that, based on the analyzes from 1999 to 2015, the value of the R factor
was 16,390 MJ mm ha-1h-1year-1, with a probability of 47% being equaled or exceeded
at least one once every 2.1 years. In the period from 2016 to 2035, the R value was
13,038 MJ mm ha-1h-1year-1. Between February to April and January to April, the
largest soil losses are likely for 1999-2015 and 2016-2035, respectively. From the analyzes carried out in this work, it was possible to indicate which periods of the year in
which more quantity and intensity of erosive events are expected.
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