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M.L. Leite & J.S.V. Filho2010. Analysis of rainfall in the Vila Velha State Park, State of Parana, Southern Brazil
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less frequent in all months, exceeding 5% frequency only in May (5.57%) and with the lowest
frequency in February (1.18%).
Table 1. Percentage corresponding to the class intervals of rainfall over the total number of days with
rainfall for each month analyzed. CRI = Classification of Rainfall Intensity; RI = Rainfall Intensity.
CRI RI (mm) J (%) F (%) M (%) A (%) M (%) J (%)
Drizzle 0,1 ├ 2,5 28,47 28,11 31,23 30,08 29,11 26,73
Light rain 2,5 ├ 10,0 31,11 32,25 33,66 27,57 29,11 29,46
Moderate rain 10,0 ├ 25,0 25,42 26,18 23,14 25,81 24,05 25,50
Heavy rain 25,0 ├ 50,0 11,94 12,28 9,55 14,79 12,15 13,37
Extreme rain > 50,0 3,06 1,18 2,43 1,75 5,57 4,95
TOTAL 100,00 100,00 100,00 100,00 100,00 100,00
CRI RI (mm) J (%) A (%) S (%) O (%) N (%) D (%)
Drizzle 0,1 ├ 2,5 25,78 27,11 22,45 24,86 26,79 28,34
Light rain 2,5 ├ 10,0 33,14 32,23 33,06 28,49 32,14 31,76
Moderate rain 10,0 ├ 25,0 24,65 26,51 26,94 29,76 30,16 26,87
Heavy rain 25,0 ├ 50,0 12,46 12,35 14,29 13,97 8,73 9,77
Extreme rain > 50,0 3,97 1,81 3,27 2,90 2,18 3,26
TOTAL 100,00 100,00 100,00 100,00 100,00 100,00
4. Discussion
The phenomenon called El Niño Southern Oscillation (ENSO), considered as the main cause of
climate variability in various regions of the globe is a phenomenon of ocean-atmosphere
interaction that occurs in the tropical Pacific Ocean and has two extreme phases: a warm phase
known as El Niño and a cold phase called La Niña (Berlato & Fontana, 2003). Among the
consequences of El Niño, is the increase in rainfall in southern South America, reaching
catastrophic proportions, as occurred in 1983 and 1998. In those years, there were registered the
two largest annual totals of rainfall in the series studied in Ponta Grossa (2494 mm in 1998 and
2217 mm in 1983). The other three largest totals of rainfall (2080.1 mm in 1957, 2071.1 mm in
1993 and 2054.7 mm in 1990) also occurred in El Niño years, although that the event was not as
strong as in 1983 and 1998. Furthermore, the La Niña phenomenon, opposite to El Niño, which
corresponds to the anomalous cooling of surface waters in the equatorial Pacific, Central and
Eastern, may explain the lowest rainfall observed in the series studied (910.3 mm in 1985).
From the standpoint of hydrology, rainfall up to 10 mm have little impact, except to moisten the
soil to the point of reaching its field capacity, increasing the efficiency of runoff into rivers.
Despite of the reduced frequency observed, the “very heavy” rains can cause further damage
such as landslides, floods, etc.. as a result of the use and occupation of land. It is very important
to make a suitable plan for land use, paying particular attention to areas of risk, as close to river
banks or slopes, which are greatly affected sites when it rains heavily. The uncertainty related to
global changes connected to precipitation, originated from natural phenomenas and/or
anthropogenic activities, makes it currently impossible to establish categorically the effects of
climate change on ecosystems and on agricultural activities more broadly. Nevertheless, studies
on various scales, including regional scale, will enable the understanding of how natural
ecosystems can respond and adapt to these climatic variability, becoming an increasingly
urgent need. Identified potential vulnerabilities, one should start the search for strategies and
technologies for adaptation, including taking advantage of possible climate changes that may be
considered beneficial.
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.