Water Balance, Climate Classification and Empirical Distribution of the Probability of Rain for the Region of Tangará da Serra – MT

Abstract

Objective: The present work aimed to describe the Climatological Water Balance (BHC), carry out the Climate Classification (CC) and evaluate the Empirical Probability (EP) of rainfall occurrence for the region of Tangará da Serra – MT.   Theoretical Frame: This study used the following main citations as a theoretical basis: National Water Agency (ANA) and National Institute of Meteorology (INMET), source of climate data; Thornthwaite & Mather (1955) for the climatological water balance methodology; Thornthwaite (1948) and Koppen (1900) for climate classification; and Thom (1966) for the methodology of probability of occurrence and return period of rain.   Method: To carry out the study, a series of 31 years of climate data was used, covering the period from 1989 to 2019, obtained from the National Water Agency (ANA) and the National Institute of Meteorology (INMET). Filling gaps in the data was carried out using the Regional Weighting method, according to the methodology of Mello et al. (2017). The climatological water balance was estimated according to Thornthwaite & Mather (1955). The climate classification was obtained using the methodologies of Thornthwaite (1948) and Koppen (1900). The probability of occurrence and the period of return of rain were achieved using the methods of Thom (1966).   Results and Conclusions: Through studies carried out, it was found that the average annual precipitation in Tangará is 1603 mm and the average annual air temperature is 24.5 °C. The months of May, June, July, August and September present a water deficit, while in the months of December, January, February, March and April there is a water surplus. According to Thornthwaite's methodology, the region has a humid climate, with moderate water deficiency in winter, megathermal and with potential evapotranspiration in the summer less than 48% of the annual potential evapotranspiration, whereas according to Koppen's methodology, the location was classified as megathermal or tropical with drought in the winter. The probability of rainfall less than the maximum average of 47.7 mm is 93.3% and its return time is approximately 15 years.   Implications of the research: This research is classified as of great importance for the purposes of the Department of Agricultural Engineering of the State University of Mato Grosso, Campus of Nova Mutum and Tangará da Serra - MT, as well as for the entire academic and scientific community and interested rural producers. in climatic data, water balance and climate of the studied region.   Originality and value: This study aimed to show the academic and scientific community and rural producers the behavior of climatic variables throughout the year in the municipality of Tangará da Serra – MT, where this information can be used for agricultural planning in the region and also serve as a basis for future studies.