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Knowledge of groundwater storage in tropical soils of the Cerrado biome is relevant because of its importance for stream flow regime in Brazil's central plateau, where rivers are perennial during the drought period of the year. The purpose of this study was to: (i) identify environmental variables capable of explaining the amplitude of groundwater variation in points of an agricultural basin in the Cerrado; and (ii) develop a statistical model to simulate the amplitude of water table variation from the chosen variables. The study was developed with monthly data obtained from 35 piezometric wells located at the Upper Jardim experimental river basin (105 km2), collected between 17/02/2004 and 01/10/2012. Two multivariate analysis methodologies were used: (i) Ordinary Least Squares regression (OLS); and (ii) Geographical Weighted Regression (GWR). Groundwater amplitude in the studied period was correlated with independent variables related to soil's physical properties and related to the basin's geomorphology, where six explanatory variables were selected to compose the statistical model. The results indicate that both OLS and GWR methodologies were capable of establishing correlations between the response and the explanatory variables. However, GWR managed to capture local correlations between the explanatory and the dependent variable that were not obtained by the OLS. Despite the complexity of groundwater behavior in tropical soils, this study demonstrates the possibility to estimate with data collected near the surface, how much water is stored in porous aquifers and groundwater behavior in soils of the Brazilian central plateau, being of great use to unmonitored river basins.

During the last decades, agriculture has drastically increased over the South American Andean Plateau (Altiplano), resulting in extensive changes in land cover from native vegetation to essentially Quinoa crop. Along with climatic variability, these land use changes appear as a catalyst in worsening the already existing drought events and water scarcity processes. Hence, understanding their relative contributions to the regional desertification process is crucial for sustainable water-use adaptation, but also is quite ambiguous because of water resource data scarcity over the Altiplano. Therefore, in the present study, an attempt to measure the impact of severe droughts and agricultural intensification on the water resources has been made using remote sensing datasets. The first step was dedicated to the validation of newly released CHIRPS v.2 precipitation and GLEAM v.3 potential evapotranspiration products by comparing their estimates with the results obtained from gauges data. Then, the Standardized Precipitation Index (SPI) was used to describe past hydro-meteorological drought events in terms of their spatial extent, duration, intensity and their impacts on the regional water resources. Finally, the dynamic trends in the spatial extent of the Quinoa crop and the meteorological conditions derived from CHIRPS v.2 and GLEAM v.3 were compared with the Vegetation Condition Index (VCI) and the Total Water Storage (TWS) derived from AVHRR and GRACE data respectively, to observe the respective influence of agriculture and climate variability on the regional hydrological system. A significant increase in Quinoa crop extent is observed from 2001 which corresponds to a significant decrease in regional VCI and TWS. Based on this trend, agriculture appears as a contributing factor in the water scarcity process over the Altiplano. The outcomes of this study will contribute to local decision making for a better water management and hydro-meteorological monitoring system.

This study assesses the performance of the new Global Precipitation Measurement (GPM)-based satellite precipitation estimates (SPEs) datasets in the Brazilian Central Plateau and compares it with the previous Tropical Rainfall Measurement Mission (TRMM)-era datasets. To do so, the Integrated Multi-satellitE Retrievals for GPM (IMERG)-v5 and the Global Satellite Mapping of Precipitation (GSMaP)-v7 were evaluated at their original 0.1&deg, spatial resolution and for a 0.25&deg, grid for comparison with TRMM Multi-satellite Precipitation Analysis (TMPA). The assessment was made on an annual, monthly, and daily basis for both wet and dry seasons. Overall, IMERG presents the best annual and monthly results. In both time steps, IMERG&rsquo, s precipitation estimations present bias with lower magnitudes and smaller root-mean-square error. However, GSMaP performs slightly better for the daily time step based on categorical and quantitative statistical analysis. Both IMERG and GSMaP estimates are seasonally influenced, with the highest difficulty in estimating precipitation occurring during the dry season. Additionally, the study indicates that GPM-based SPEs products are capable of continuing TRMM-based precipitation monitoring with similar or even better accuracy than obtained previously with the widely used TMPA product.

The purpose of this study was to analyze the soil database influence on streamflow simulation using the SWAT model in the experimental catchment of the Pipiripau river (235 km²), located in Brazilian savanna (Cerrado biome). To achieve this goal, two databases were used, one developed with data collected nearby the Pipiripau region (SDB1), and another one with data from literature (SDB2). The evaluation was performed using a streamflow historical time series of 10 years (1989-1998), on monthly and daily basis. The analysis was made without calibration, using only the results from SWATs first simulation, as it was applied in an ungagged basin. For daily simulations, the Nash & Sutcliffe model efficiency (NSE), the adapted Nash & Sutcliffe model efficiency (ANSE), and the Percent Bias (PBIAS) were respectively -11.88, -11.80, and -23.15% for SDB1, and -9.94, -9.88, and -84.72, for SDB2. For the monthly simulations, the NSE, ANSE, and PBIAS results were, respectively,-1.78, -2.98, and -24.53% for SDB1, and 6.51, 9.88, and -84.72 for SDB2. Even if the PBIAS analysis and the annual water budget results for the SDB1 simulations had better results, the negative values of NSE and ANSE indicates that, without calibration, the simulations failed to represent observed data. It is remarkable that the use of SDB1 visibly improved daily baseflow simulations during the rainy season. The results indicate the importance of developing specific soil databases for different regions, as well as research on other parameters in order to improve SWATs physical basis.

O Cerrado rupestre é a comunidade vegetal que ocupa afloramentos de arenito e quartzito. Este é ainda encontrado em bom estado de conservação principalmente devido ao acesso relativamente restrito maioria de suas áreas. Ocorre na Serra Dourada - GO onde foi objeto do presente estudo na Estância Quinta da Serra (16o 02ââ?¬â?¢ 01ââ?¬Â S e 50o 03ââ?¬â?¢ 41ââ?¬Â W) que visa avaliar a fitossociologia e a estrutura diamétrica do seu componente lenhoso. Para o inventário permanente foram aplicadas 10 parcelas de 20 x 50 m para a avaliação dos indiví­duos com Db30cm ââ?°¥ 5 cm, inclusive os mortos em pé. Foram encontradas 54 espécies de 43 gêneros e 25 famí­lias. O H= 3,13 nats.ind-1, equalibilidade Jââ?¬â?¢=0,79, Chao 1= 66 e Chao 2 = 63 espécies refletem a alta diversidade florí­stica na amostra. A densidade total foi 1.137 ind.ha-1 e a área basal total foi 7,085 m2.ha-1. As espécies mais importantes foram Andira vermifuga Mart. Ex Benth, Qualea parviflora Mart., Wunderlichia crulsiana Taub., Anacardium occidentale L. e Heteropterys byrsonimifolia A. Juss. A comparação com a fitossociologia de outras 23 áreas de cerrado sentido restrito no Brasil Central, em diferentes classes de solos, estudadas com o mesmo método, ressaltou diferenças florí­sticas e estruturais entre as áreas. A distribuição dos diâmetros indicou a tendência auto-regenerativa para a comunidade, onde 96% dos indiví­duos apresentaram Db30cm < 15 cm. O maior Db30cm foi de 41,06 cm anotado para um indiví­duo de Caryocar brasiliense Cambess. O pequeno crescimento em diâmetro parece ser uma das limitações impostas aos indiví­duos nestes ambientes. Os indiví­duos mortos ââ?¬Å?em péââ?¬Â representaram apenas 2,2% da densidade total, 2,3% da área basal total e ocorreram em 70% das parcelas, o que salienta o estado de conservação da vegetação local. O cerrado rupestre estudado é composto por 21 (38,9%) espécies amplamente distribuí­das no Bioma, é portanto, fonte potencial de sementes e propágulos para recuperação de áreas degradadas em diferentes classes de solos na região.