SUMMARYThe Brazilian East coast was intensely affected by deforestation, which drastically cut back the original biome. The possible impacts of this process on water resources are still unknown. The purpose of this study was an evaluation of the impacts of deforestation on the main water balance components of the Galo creek watershed, in the State of Espírito Santo, on the East coast of Brazil. Considering the real conditions of the watershed, the SWAT model was calibrated with data from 1997 to 2000 and validated for the period between 2001 and 2003. The calibration and validation processes were evaluated by the Nash-Sutcliffe efficiency coefficient and by the statistical parameters (determination coefficient, slope coefficient and F test) of the regression model adjusted for estimated and measured flow data. After calibration and validation of the model, new simulations were carried out for three different land use scenarios: a scenario in compliance with the law (C1), assuming the preservation of PPAs (permanent preservation areas); an optimistic scenario (C2), which considers the watershed to be almost entirely covered by native vegetation; and a pessimistic scenario (C3), in which the watershed would be almost entirely covered by pasture. The scenarios C1, C2 and C3 represent a soil cover of native forest of 76, 97 and 0 %, respectively. The results were compared with the simulation, considering the real scenario (C0) with 54 % forest cover. The NashSutcliffe coefficients were 0.65 and 0.70 for calibration and validation, respectively, indicating satisfactory results in the flow simulation. A mean reduction of 10 % of the native forest cover would cause a mean annual increase A costa leste brasileira passou por vasto processo de desmatamento, reduzindo drasticamente seu bioma original. Os possíveis impactos desse processo sobre os recursos hídricos ainda são desconhecidos. Objetivou-se com este trabalho avaliar os impactos do desmatamento sobre os principais componentes do balanço hídrico da bacia hidrográfica do córrego do Galo, ES, localizada na costa leste do Brasil. Para as condições atuais da bacia, o modelo SWAT foi calibrado, no período entre 1997 e 2000, e validado, entre 2001 e 2003. Os processos de calibração e validação foram avaliados pelo coeficiente de Nash-Sutcliffe e pelos parâmetros estatísticos (coeficiente de determinação, coeficiente angular e teste F) da regressão ajustada entre a vazão medida e estimada. Depois do modelo calibrado e validado, novas simulações foram realizadas, considerando três cenários distintos de uso do solo: o legalmente ideal (C1), que leva em consideração a preservação em áreas de APPs; o otimista (C2), que considera a bacia em quase sua totalidade preservada por vegetação nativa; e o pessimista (C3), que considera a bacia coberta em quase sua totalidade por pastagem; o que corresponde a 76, 97 e 0 % de cobertura florestal nativa. Os resultados foram comparados com a simulação realizada com o cenário atual (C0), com 54 % da área coberta com floresta. Os valores d...
This study aimed at evaluating the replacement of inorganic copper, manganese, and zinc sources by organic sources in the diet of laying hens during the second laying cycle in trace mineral excretion, egg production, and eggshell quality. Two hundred and fifty 100-week-old Dekalb hens were distributed according to a completely randomized design into five treatments with five replicates of ten birds each. The control treatment consisted of a basal diet with all trace minerals in the inorganic form. The other treatments consisted of a basal diet with a mixture of the minerals copper, manganese, and zinc in the organic form with concentrations of 100%, 90%, 80%, and 70% of the levels of inclusion of inorganic mineral sources in the control treatment. Trace mineral excretion was determined in five layers per treatment by the method of total excreta collection. Excreta trace mineral contents were determined by atomic absorption spectrophotometry. Egg production and eggshell quality were determined by the mass of the eggs and the egg specific gravity, respectively. For all trace minerals examined, the dietary supplementation with organic sources reduced trace mineral excretion compared with the control group, even at 70% inclusion level, without compromising egg production or eggshell quality. The replacement of the inorganic trace mineral sources by organics source effectively reduced the excretion of copper, manganese, and zinc by laying hens in the second laying cycle.
A morfometria de uma bacia hidrográfica pode fornecer subsídios para o adequado planejamento e gestão de recursos hídricos em nível de bacia hidrográfica. Neste sentido, objetivou-se com este estudo realizar a análise morfométrica de uma sub-bacia hidrográfica do Rio Piracicaba (MG), utilizando o Sistema de Informações Geográficas. A área de drenagem e o perímetro da bacia estudada foram estimados em 1.138,80 km² e 205,16 km, respectivamente. A análise dos parâmetros de forma, do sistema de drenagem e do relevo da bacia aponta, respectivamente, baixa susceptibilidade a ocorrência de enchentes, baixa capacidade de drenagem, potencial de degradação por erosão do solo e ocorrência de precipitações bem distribuídas e regulares. O uso de dados advindos de imageamento por satélites integrado às técnicas de geoprocessamento comprovou elevada eficiência como ferramenta para ações atreladas ao planejamento e gestão dos recursos hídricos, sendo ainda eficiente na redução de custos, tempo e padronização científica na execução de experimentos.
Alguns elementos químicos são essenciais à vida em pequenas quantidades, no entanto, grandes quantidades podem comprometer a qualidade do curso hídrico e ocasionar danos à saúde. O objetivo deste trabalho foi quantificar a presença de alguns elementos químicos potencialmente tóxicos em um trecho do rio Turvo Sujo, localizado na cidade de Viçosa-MG em diferentes vazões. Nesse rio, foram escolhidos cinco pontos de coleta, as quais foram realizadas nas quatro diferentes estações do ano. Para cada ponto foram obtidas as concentrações de cobre, manganês, ferro, zinco, crômio, cádmio e chumbo. As concentrações de ferro e manganês foram maiores na época do verão, em razão do maior escoamento superficial nesse período, enquanto os elementos mais tóxicos, como o crômio, cádmio e chumbo, foram observados em maiores concentrações no período da primavera, época correspondente à menor vazão.
Land-use changes promote significant variations in streamflow regimes, and hydrological models allow studying their impacts. Based on this approach, this study aimed to assess the applicability of the SWAT model for different land-use scenarios and their respective impacts on the flow regime of the Mucuri River. The average monthly and daily water balance was generated after the calibration and validation of the SWAT model in the basin. Three land-use scenarios were analyzed in relation to the current land use, as follows: replacement of the agricultural area by the eucalyptus crop, replacement of the native forest area by the sugarcane crop, and replacement of pasture by exposed soil. The results showed that the SWAT model is adequate to simulate the land-use change and its impact on the flow regime of the Mucuri River; the replacement of agriculture by eucalyptus in the basin led to a decrease in the average and minimum reference streamflows; and the replacement of the forest cover by sugarcane and pasture by exposed soil provided an increase in the average and minimum reference streamflows.
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