Análise de correlação entre a produção primária bruta do sensor MODIS e balanço hídrico do SWAT para bacia hidrográfica do Riacho do Pontal, Pernambuco

Abstract

The correlation between gross primary production and the water balance of the Riacho do Pontal watershed, located in the state of Pernambuco, Brazil, was evaluated. For this, the components of precipitation (PRECIP), water production (WYLD), soil water storage (SW), surface runoff (SURQ), potential evapotranspiration (PET) and actual evapotranspiration (ET) of the water balance were used simulated by the SWAT model and the MOD17A2H remote sensing product of Gross Primary Productivity (GPP) from the MODIS (MODerate Resolution Imaging Spectroradiometer) sensor. The data obtained by the MODIS sensor and the SWAT model were analyzed and then correlated using Spearman correlation coefficient. The results show that the minimum GPP with runoff had the lowest correlation value of the entire analysis (of 0.13), a negative correlation with the potential evapotranspiration (of -0.63) and positive with the other components of the balance water, ranging from 0.22 with precipitation to 0.38 with actual evapotranspiration. With the average GPP, there was a negative correlation for potential evapoternspiration (from -0.74), and with the other components of the water balance, there was a positive correlation, ranging from 0.36 with runoff to 0.6 with real evapotranspiration. At maximum GPP, there was again a negative correlation with potential evapotranspiration (from -0.76), and a positive correlation with all other components of the water balance, ranging from 0.28 with runoff to 0.46 with actual evapotranspiration and water production. The existence of a correlation between the gross primary production and the water balance was observed, even if it is low, as occurred between the minimum GPP and the runoff. The correlation between GPP and real and potential evapotranspiration was greater than the correlation between GPP and the other components of the water balance, with the exception of the maximum GPP with water production, which had the same value as the maximum GPP with the real evapotranspiration. Thus, monitoring evapotranspiration in semiarid regions is of great importance for predicting gross primary production. And according to the predictions of the Intergovernmental Panel on Climate Change (IPCC), which predicts the increase of extreme events in semiarid regions, it is possible to say that if climate change scenarios come to occur, there is a strong trend in production primary gross, in semiarid regions, decrease.