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The understanding of the hydrological behavior of a region is important for the development of activities and socioeconomic enterprises and regional environmental management. Nevertheless, the hydrological monitoring network of a country sometimes does not represent the whole area or the historical series have flaws that must be filled. These problems are more serious in watersheds with greater relevance, as in the case of Rio das Mortes, which is part of the Rio Grande basin that has great hydroelectric potential. Thus,

This study investigates the applicability of Satellite Precipitation Products (SPPs) in streamflow simulations performed in the Brazilian Cerrado biome, which is one of the world’s biodiversity hotspots. Local data from ground observations were used as a reference for evaluating the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG). The Soil and Water Assessment Tool (SWAT) was used to simulate the streamflow in a subbasin of the Tocantins river basin. Statistical precision metrics showed that both SPPs presented a satisfactory performance for precipitation monitoring on a monthly scale, in which IMERG performed better than TMPA. The Nash–Sutcliff coefficient and Kling–Gupta efficiency obtained for both calibration and validation period were greater than 0.82 and 0.79, respectively, demonstrating that both SPPs were able to simulate the hydrological regime adequately. However, the bias indicated that the SPPs overestimated the observed streamflow. The r-factor and p-factor values showed that both TMPA and IMERG presented low uncertainty in streamflow simulations. SPPs offer a great alternative for monitoring the precipitation and hydrological studies in the Brazilian Cerrado biome, and presented better simulation results than rain gauges.

ABSTRACT Meteorological drought is a natural hazard characterized as below-average precipitation from expected or normal that can affect various economic sectors, and lead to period with inadequate streamflow for established uses of the water (hydrological drought). We aimed to apply the Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI) to identify the occurrence and the intensity of droughts in Doce River Basin (DRB), Southeastern Brazil. For this purpose, 71 rain gauge stations and one streamflow station were selected with 30-year monthly historical series (1987 to 2017). The SPI and SSI were calculated for the hydrological year (October-September) and the seasons (Spring, Summer, Fall, and Winter). SPI mapping was performed by geostatistical procedures. Pearson's coefficient was calculated to analyze the influence of meteorological on hydrological drought. The main meteorological drought events, observed in the hydrological years of 1994/95, 2000/01, and a recent and consecutive period of four hydrological years (2013-2017), were mainly influenced by events in spring and summer and, to a lesser extent, in fall. It was observed the influence of the meteorological drought on the hydrological drought on an annual and seasonal scale, except winter, where low precipitation does not influence in the streamflow.

The Brazilian savanna is one of the world’s 25 biodiversity hotspots. However, droughts can decrease water availability in this biome. This study aimed to analyze meteorological and hydrological droughts and their influence on the hydrological behavior in a Brazilian savanna basin. For that, hydrological indicators were calculated to analyze the hydrological behavior in the Pandeiros river basin (PRB). The Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI) were calculated for the hydrological year and rainy season from 1977 to 2018. The propagation of the meteorological to hydrological drought was studied by means of the Pearson coefficient of correlation between the SSI and SPI with 0, 3, 6, 9, and 12-month lags. A longer meteorological drought was observed from 2014/15 to 2017/18 which caused a reduction in the groundwater recharge, besides potentially reducing the ecological functions of the Brazilian savanna. This drought was intensified by an increase in the average annual temperature, resulting in the increasing of evapotranspiration. Regarding drought propagation, there is no significant difference among the coefficients of correlation from 0 to 6-month lags. For the lags of 9 and 12 months, the correlation decreases, indicating a greater influence of the current rainy season than the past ones.