Erosão hídrica pós-plantio em florestas de eucalipto na bacia do rio Paraná, no leste do Mato Grosso do Sul

Nas regiões tropicais, o desgaste provocado no solo por ação das águas da chuva, ou seja, a erosão hídrica é a mais importante forma de degradação do solo. Visto que os plantios florestais de eucalipto estão inseridos em ecossistemas sensíveis às perturbações antrópicas em razão de ocorrência de plantações em solos com baixos teores de argila, com baixa fertilidade natural e grande parte das plantações estabelecidas em antigas áreas agrícolas e de pastagens degradadas, surge a necessidade do entendimento dos processos que regem a erosão hídrica e suas relações com as perdas de solo e água nos sistemas florestais. Objetivaram-se com este trabalho calcular os valores de erosividade da chuva (fator R - EI30), estimar a tolerância de perda de solo (T) para as classes representativas nas áreas de estudo, avaliar as perdas de solo e água por erosão hídrica e verificar a influência, por meio de análise de componentes principais (ACP), de atributos físicos e matéria orgânica do solo sobre a erosão hídrica em florestas de eucalipto no estádio de pós-plantio. Os tratamentos constituíram de diferentes sistemas de manejo dos resíduos e da disposição de plantio (nível e desnível), em dois biomas distintos, Cerrado e Floresta, e solo descoberto. Os solos foram classificados como Latossolo Vermelho distrófico típico textura média-alta fase floresta (LVd1) e Latossolo Vermelho distrófico típico textura média-baixa fase cerrado (LVd2). O estudo foi realizado em áreas experimentais de plantio de eucalipto localizadas no município de Três Lagoas, na bacia do Rio Paraná, no leste do Mato Grosso do Sul. O índice de erosividade anual obtido foi de 6.792,7 MJ mm ha-1 h-1 ano-1. Os valores de T variaram de 9,0 a 11,0 Mg ha-1 ano-1, para o LVd2 e LVd1, respectivamente. As perdas de solo apresentaram valores em torno de 0 a 0,505 Mg ha-1 no LVd1 e de 0 a 0,853 Mg ha-1, no LVd2. A ACP evidenciou-se eficiente na discriminação dos sistemas de manejo em razão da interação entre os atributos físicos e matéria orgânica do solo e suas relações com a erosão hídrica, possibilitando visualizar de forma clara a influência do manejo sobre esses atributos e a relação de ambos com as perdas de solo e água

CABra: A novel large-sample dataset for Brazilian catchments

In this paper, we present the Catchments Attributes for Brazil (CABra), which is a large-sample dataset for Brazilian catchments that includes long-term data (30 years) for 735 catchments in eight main catchment attribute classes (climate, streamflow, groundwater, geology, soil, topography, land cover, and hydrologic disturbance). We have collected and synthesized data from multiple sources (ground stations, remote sensing, and gridded datasets). To prepare the dataset, we delineated all the catchments using the Multi-Error-Removed Improved-Terrain Digital Elevation Model (MERIT DEM) and the coordinates of the streamflow stations provided by the Brazilian Water Agency, where only the stations with 30 years (1980-2010) of data and less than 10% of missing records were included. Catchment areas range from 9 to 4 800 000 km2, and the mean daily streamflow varies from 0.02 to 9mmd-1. Several signatures and indices were calculated based on the climate and streamflow data. Additionally, our dataset includes boundary shapefiles, geographic coordinates, and drainage area for each catchment, aside from more than 100 attributes within the attribute classes. The collection and processing methods are discussed, along with the limitations for each of our multiple data sources. CABra intends to improve the hydrology-related data collection in Brazil and pave the way for a better understanding of different hydrologic drivers related to climate, landscape, and hydrology, which is particularly important in Brazil, having continentalscale river basins and widely heterogeneous landscape characteristics. In addition to benefitting catchment hydrology investigations, CABra will expand the exploration of novel hydrologic hypotheses and thereby advance our understanding of Brazilian catchments' behavior. The dataset is freely available at https://doi.org/10.5281/zenodo.4070146 and https://thecabradataset.shinyapps.io/CABra/(last access: 7 June 2021). © 2021 André Almagro et al.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Effects of climate and land cover changes on water availability in a Brazilian Cerrado basin

The effects of riparian restoration and soil and water conservation practices on catchment hydrology are still unclear. Here, we assess whether a positive change in soil and water conservation practices and riparian reforestation will affect the water availability and boost resilience in a Brazilian Cerrado basin under climate change scenarios. This study was developed in the Três Marias basin (50.600 km²) located in southeastern Brazil. First, we calibrated (1992–2005) and evaluated (2006–2012) the Soil and Water Assessment Tool (SWAT) model. Then, we created a land cover and land use change (LCLUC) scenario that considers improving soil and water conservation practices and the reforestation of riparian zones, following the recommendations of the Brazilian Payment for Ecosystem Services (PES). We also used the trend SSP2-4.5 and the fossil-based economy SSP5-8.5 (Shared Socioeconomic Pathways) climate scenarios data from the Coupled Model Intercomparison Project Phase 6 (CMIP6) project for the period of 2015–2100. Along with a decrease of 5 %–15 % in precipitation in the projected period, an increase of 7 %–15 % in forest areas due to the LCLUC scenarios generated an increase in evapotranspiration values up to 38 %, resulting in a decrease of surface runoff and baseflow. Riparian reforestation and soil and water conservation practices did not necessarily enhance water availability on the simulations performed, as expected by many PES. © 2021 The Author(s)Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Significant baseflow reduction in the sao francisco river basin

Water scarcity is a key challenge to global development. In Brazil, the Sao Francisco River Basin (SFB) has experienced water scarcity problems because of decreasing streamflow and increasing demands from multiple sectors. However, the drivers of decreased streamflow, particularly the potential role of the surface-groundwater interaction, have not yet been investigated. Here, we assess long-term trends in the streamflow and baseflow of the SFB during 1980–2015 and constrain the most likely drivers of observed decreases through a trend analysis of precipitation (P), evapotranspiration (ET), and terrestrial water storage change (TWS). We found that, on average, over 86% of the observed decrease in streamflow can be attributed to a significant decreasing baseflow trend along the SFR, with a spatial agreement between the decreased baseflow, increased ET, and irrigated agricultural land in the Middle SFB. We also noted a decreasing trend in TWS across the SFB exceeding –20 mm year−1 . Overall, our findings indicate that decreasing groundwater contributions (i.e., baseflow) are providing the observed reduction in the total SFR flow. A lack of significant P trends and the strong TWS depletion indicate that a P variability only has likely not caused the observed baseflow reduction, in mainly the Middle and Sub-middle SFB. Therefore, groundwater and surface withdrawals may likely be a driver of baseflow reduction in some regions of the SFB. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Gridded 20-year climate parameterization of Africa and South America for a stochastic weather generator (CLIGEN)

CLIGEN is a stochastic weather generator that creates statistically representative timeseries of daily and sub-daily point-scale weather variables from observed monthly statistics and other parameters. CLIGEN precipitation timeseries are used as climate input for various risk-assessment modelling applications as an alternative to observe long-term, high temporal resolution records. Here, we queried gridded global climate datasets (TerraClimate, ERA5, GPM-IMERG, and GLDAS) to estimate various 20-year climate statistics and obtain complete CLIGEN input parameter sets with coverage of the African and South American continents at 0.25 arc degree resolution. The estimation of CLIGEN precipitation parameters was informed by a ground-based dataset of >10,000 locations worldwide. The ground observations provided target values to fit regression models that downscale CLIGEN precipitation input parameters. Aside from precipitation parameters, CLIGEN’s parameters for temperature, solar radiation, etc. were in most cases directly calculated according to the original global datasets. Cross-validation for estimated precipitation parameters quantified errors that resulted from applying the estimation approach in a predictive fashion. Based on all training data, the RMSE was 2.23 mm for the estimated monthly average single-event accumulation and 4.70 mm/hr for monthly maximum 30-min intensity. This dataset facilitates exploration of hydrological and soil erosional hypotheses across Africa and South America. © 2022 The Author(s). Published by Taylor & Francis Group and Science Press on behalf of the International Society for Digital Earth, supported by the International Research Center of Big Data for Sustainable Development Goals, and CASEarth Strategic Priority Research Programme.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Bentonites modified with phosphomolybdic heteropolyacid (HPMo) for biowaste to biofuel production

Two bentonites from Paraíba (Northeastern Brazil) were impregnated with heteropoly phosphomolybdic H 3 PMo 12 O 40 (HPMo). The materials produced were characterized by various techniques such as N 2 adsorption-desorption (specific surface area, SSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA/DTG), Scanning Electron Microscopy (SEM) equipped with Dispersive Energy X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), acid-base titration analysis. The catalytic activity of these materials was tested in the esterification of a waste from palm oil deodorization and the main results obtained (about 93.3% of conversion) indicated that these materials have potential to act as heterogeneous solid acid catalysts. The prepared materials exhibited satisfactory catalytic performance even after a very simple recycling process in three reuse cycles, without significant loss of their activities. © 2019 by the authors