Índice de anomalia da precipitação pluvial como subsídio ao planejamento agrícola e urbano em Tracuateua-PA

Abstract

The life of human populations is directly impacted by the spatio-temporal variations of rain events, knowledge about the dynamics of rainfall is essential for the establishment of good territory management, being important for urban planning to decrease and to reduce risks in the sector agricultural. Thus, this study aimed to analyze and discuss the variability of rainfall by means of anomaly rates, between the periods from 1973 to 2019 in the municipality of Tracuateua-Pa. The study used precipitation data from the meteorological station of the National Institute of Meteorology (INMET) in Tracuateua from January 1973 to December 2019. The classification of dry and wet periods was performed using the Rain Anomaly Index (IAC) with the analysis of the degree of severity and the frequency of dry and rainy years. The historical average for the region was 2,398.32 mm / year, reaching a minimum of 1,381.70 mm in 1983 under the influence of the La Niña event and a maximum of 4,084.40 mm in 1985 under the influence of the La Niña event. Considering all 41 years of the studied time series, 22 years (53.6%) had accumulated rainfall below the average and 19 years (46.4%) with rain above the historical average. Of this total, 10 years (24.4%) were classified as extremely dry or very dry and 6 years (14.6%) were classified as extremely rainy or very rainy. It was possible to observe three periods that presented three or more consecutive years of drought: 1st period 1978, 1979, 1980,1982 and 1983; 2nd period 1996, 1997 and 1998; 3rd period 2012, 2014, 2015, 2016 and 2017. Regarding the years classified as rainy, two periods were identified that presented three or more consecutive years of drought: 1st period 1999, 2000 and 2001; 2nd period 2007, 2008 and 2009. A rainier period was investigated (January to June), which presents a greater volume of rain concentrated in the months of February, March and April due to the performance of the Intertropical Convergence Zone (ZCIT), which operates in the region mainly at this time of year. The least rainy period (July to December) has the peak of drought in the months of September, October and November. It is inferred that the use of the IAC was an effective technique to analyze rainfall dynamics in the region, this study generated preliminary information for other research and to be used with discretion in decision making for the purposes of urban planning and agricultural activities.