Análise pretérita e prognóstica do Balanço Hídrico Climatológico (BHC) da Bacia Hidrográfica do Rio Paranaíba - Brasil

Abstract

It was decided to develop this thesis for the drainage basin of the Paranaíba River - Brazil, due to its importance for the national context, as it is an interstate drainage basin with a drainage area of 222.6 thousand km², covering approximately 2.6% of the national territory, with its economic base mainly agricultural. Therefore, it is necessary to rethink on a daily basis the adoption of methodologies that can help the various planning sectors (rural and/or urban) to make assertive decisions. With this in mind, the climatological water balance (BHC) proposed by Thornthwaite and Mather (1955) has been an indispensable tool, where, in a simplified way, one can account for the dynamics of water in the soil, i.e., it brings the flows corresponding to the inflow and outflow of water, and this factor is calculated over time. Seeking to know the applicability of the climatological water balance (BHC) proposed by Thornthwaite and Mather (1955), the objective is to verify all its temporal-spatial dynamics, i.e., to evaluate its dynamics in the past and then seek to evaluate it prognostically. For this work to be carried out, a database was used composed of 10 climatological stations belonging to INMET, contemplating a temporal and/or historical series from 1991 to 2021, except for the station EC10 - Araxá that contemplated from 1991 to 2017, and this station was adopted for the southern region of the basin in order to compose a better distribution. The sum total of rainfall among the adopted stations was 412,697.0 mm, and when analyzing seasonally the average rainfall totals it is observed that the general average for the period considered rainy was 1,283.4 mm, while for the dry period it was 202.6 mm, that is, the difference between both periods is 1,080.9 mm, which is an average value considered ideal for the period evaluated. Statistically, the trend analysis proposed by Mann-Kendall indicated that most stations presented TNSQ (non-significant tendency to decrease), with the exception of stations EC01 - Brasília that presented TNSA (non-significant tendency to increase) and EC10 - Araxá with TSQ (significant tendency to decrease). The temperature data (maximum, average and minimum), showed the greatest amplitude at station EC05 - Jataí totaling 13.9°C. After checking the rainfall and temperature indices, the climatological water balance (BHC) analysis was applied, highlighting that during the entire period evaluated the stations EC01 - Brasília and EC10 - Araxá remained well below the overall average rainfall and temperature of the watershed and, Statistically evaluating the rainfall by the Mann-Kendall method, stations EC06 - Paracatu and EC10 - Araxá, showed TNSA (no significant upward trend), while the others showed TSA (significant upward trend), a result that draws attention to any sector of planning. Individually, stations EC06 - Paracatu, EC07 - Paranaíba, showed longer periods of water deficiency while the others showed practically the same period of water deficiency. Prognostically, the IPCC AR6 report was used and based on the SSP2 - 4.5 scenario, considered to be median, we found that in all the proposed prognostic scenarios there will be an increase of the water deficit, which could characterize possible areas of desertification in the basin. Finally, the climatic typological characterization of the basin characterized it preteritatively on the typology B1sA'a' and prognostically evolved among the proposed scenarios among the typologies C2sA'a', C1wA'a' and D2dA'a', thus characterizing possible climatic impacts.