RESUMO:A distribuição da precipitação numa bacia hidrográfica durante o ano é um dos fatores determinantes para quantificar a necessidade de irrigação de culturas e de abastecimento de água doméstico e industrial, além de estudos para o controle de inundações e da erosão do solo. O potencial da chuva em causar erosão hídrica pode ser avaliado por meio de índices que se baseiam nas características físicas das chuvas de cada região, entre os quais se destacam índice de erosividade. Analisaram-se, neste trabalho, a espacialização da precipitação pluvial e o índice de erosividade médio anual e mensal na Bacia Hidrográfica do Rio Dourados. Analisando os resultados obtidos, foi possível concluir que: o regime de precipitação apresenta oscilação unimodal, com período chuvoso compreendido entre os meses de outubro e março; todos os meses da estação chuvosa apresentam drásticas reduções da precipitação média; a erosividade média anual variou de 3.192,0 a 4.977,0 MJ mm ha -1 h -1 ano -1 ; e os meses de dezembro a janeiro apresentam os maiores riscos de ocorrência de perdas de solo por erosão hídrica. PALAVRAS-CHAVE:precipitação média, índice de erosividade, perda de solo. RAINFALL AND EROSION SPACIALIZATIONIN DOURADOS RIVER BASIN, MS, BRAZILABSTRACT: The distribution of rainfall in a watershed bay during the year is one of the determining factors to quantify the need for irrigation of crops and domestic and industrial water supply, beyond studies to control flooding and soil erosion. The rain potency to cause erosion can be assessed by indices that are based on physical rainfall characteristics in each region, which erosion is an index. In this study it was analyzed the yearly and monthly indices of rainfall and erosion spacialization in Dourados Watershed Bay. According with the results it was possible to conclude: the rainfall presented a unimodal oscillation, the rainy season ranged from October to March, every month of the rainy season showed a dramatic reductions in the average rainfall, the yearly erosion ranged from 3.192,0 to 4.977,0 MJ mm ha -1 h -1 year -1 , and the highest risks of soil loss by water erosion was in the months of December and January.
ResumoO objetivo deste estudo foi adaptar a proposta metodológica de Ross (1994) para novos procedimentos de determinação da fragilidade ambiental. Para o trabalho de geoprocessamento, foi utilizado o Sistema de Informação Geográfica (SIG) SPRING, tendo como bases cartográficas imagens LANDSAT/TM 5. Foram gerados os mapas de fragilidade potencial e emergente. O primeiro foi elaborado por meio da sobreposição dos planos de informação de declividade, erodibilidade, erosividade e geologia. Para a geração do mapa de fragilidade emergente, efetuou-se a sobreposição do mapa de fragilidade potencial ao mapa de uso da terra. Os resultados demonstraram que: a adaptação da base metodológica com a integração dos fatores de análise declividade, erodibilidade, erosividade e geologia promoveram diferenciação significativa na elaboração do mapa final de fragilidade ambiental; a utilização da classificação contínua por meio da média ponderada permitiu uma análise da fragilidade ambiental condizente com a escala de trabalho utilizada; os SIG, por meio do SPRING e da álgebra de mapas, demonstraram eficácia na análise da fragilidade ambiental, atestando a possibilidade de aplicação da metodologia em estudos de planejamento ambiental em bacias hidrográficas. Palavras-chave: Vulnerabilidade; sistema de informação geográfica (SIG); uso da terra. AbstractDetermination of environmental fragility of watersheds. The aim of this study was to promote the adaptation of new procedures for determining the environmental fragility of watersheds, based on the method proposed by Ross (1994), taking as a case study the Dourados river watershed. For the geoprocessing was used the Geographic Information System (GIS) and LANDSAT/TM 5 images as a cartographic base. The maps of potential and emerging fragility were generated. The first was prepared by the overlapping of layers of slope, erosivity, erodibility and geology, and the emerging fragility map was obtained by cross referencing the map of potential fragility with the map of soil use. Results showed that: the adaptation of the methodological with the integration of factors of analysis such as slope, erodibility, erosivity and geology promoted a significant differentiation in the production of the final map for environmental fragility; the use of continuous ratings by the weighted average allowed for an analysis of the environmental fragility according to the scale of work used; the SPRING (GIS) software, combined with algorithms of map algebra, demonstrated effectiveness proved effective in the theoretical analysis of environmental fragility, confirming the possibility of applying the methodology in studies of environmental planning of watersheds. Keywords: Vulnerability; geographic information system (GIS); land use. INTRODUÇÃOA influência antrópica no ambiente, inclusive em bacias hidrográficas, tem sido motivo frequente de preocupação na sociedade, o que tem levado ao aumento de pesquisas para qualificar e quantificar impactos da ocupação territorial. Nesse contexto, tem se tornado primordial...
-The objective of this work was to evaluate soybean (Glycine max) grain yield and the establishment of perennial intercropped forages. Soybean was evaluated in sole crop and intercropped with the following forages: Megathyrsus maximus, Aruana and BRS Tamani cultivars; Urochloa brizantha, Xaraés, BRS Piatã, and BRS Paiaguás cultivars; U. decumbens; and U. ruziziensis. A randomized complete block design was used, with seven replicates, in the 2011/2012 and 2012/2013 crop seasons. In the intercropped system, the forages were sown 21 and 14 days after soybean emergence, in the first and second crop seasons, respectively. Grain yield did not differ for soybean in sole crop or intercropped, except for soybean + U. ruziziensis and soybean + 'BRS Paiaguás', which were less productive in the second year of evaluation. The 'BRS Tamani' forage was the most suited for intercropping with soybean, considering its morphological characteristics and its low competition potential. Soybean intercropped with perennial forages contributes to suppress weed growth and, overall, does not compromise soybean yield.
Exposure scenarios in combination with simulation models have been used in the procedure of Environmental Risk Assessment (ERA) of pesticides to estimate exposure concentrations in environmental compartments.The appropriate definition of exposure scenarios is primordial to guarantee ERA purpose to evaluate if a pesticide use in an intended area can be considered safe. This work had the aim to present and test a geo-and statistically based approach to define worst-case groundwater exposure scenarios for Brazil. To do so, soil-climate data of Mato Grosso do Sul state consisting of 42 locations (3 soil classes and 14 meteorological stations) were used to generate populations of Predicted Environmental Concentrations (PEC) at 3 and 5-m depth for a simulation period of 24 years. A total of 3,780 graphs were generated of PEC populations for 15 "dummy" pesticides. After setting equal risks in both dimensions (spatial and temporal) equal to 20%, the overall risks exceedance of tested worst-case groundwater exposure scenarios were about 10% for both depths. Thus, this approach can be considered suitable to guarantee a pre-defined overall risk exceedance once defined by the regulatory authorities in Brazil.
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