Impacto do balanço hídrico em diferentes tipos de solos: comparação entre dados de radar-pluviômetro e análise de tendência da chuva em área agrícola
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Data
2008-02-08
Autores
Emídio, Zildene Pedrosa de Oliveira [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A presente pesquisa foi realizada com a finalidade de comparar e avaliar o desempenho de um balanço hídrico, denominado balanço hídrico distribuído – BHD devido a sua alta resolução espacial. Com base nos mapas pedológicos das áreas das quadrículas de Assis e Piracicaba, o BHD foi executado em 19 períodos decendiais, entre 21/outubro/2004 a 29/abril/2005, objetivando determinar o percentual de água disponível no solo (AD%) a cada 1 km². Como dado de entrada na equação do BHD, a chuva média nas áreas citadas foi quantificada de duas formas: pelos pluviômetros, através do método dos polígonos de Thiessen e pelo radar meteorológico, obtida através da relação Z-R específica, sendo Z fator de refletividade do radar e R a taxa de precipitação. Os dados de radar foram obtidos por meio de imagens do produto CAPPI (Constant Altitude Plan-Position Indicator) num raio de 240 km, com altura de 3,5 km, a cada 7,5 ou 15 minutos, amostradas pelo radar meteorológico Doppler, banda S, localizado em Bauru/SP e operado no IPMet/UNESP e foram processados permitindo que as chuvas fossem integradas em períodos decendiais sobre pixels do radar, com resolução de 1 km x 1 km. Para a avaliação do comportamento espacial da chuva medida com o radar, utilizou-se a técnica de análise de superfície de tendência (Trend Surface Analysis) com regressão polinomial de primeiro grau em um modelo de grade de 51 X 51, elaborado pelo programa SURFER®, v. 7, objetivando o mapeamento e a identificação dos resíduos positivos (excesso de chuva) e negativos (falta de chuva) nas áreas de Piracicaba e Assis. Os resultados do BHD executados com os dados do pluviômetro e radar, mostraram diferença do campo de distribuição de água disponível nas áreas de Assis e Piracicaba.
The present research was carried out with the aim of assessing and comparing the performance of an specific water balance process, denominated Distributed Water Balance (acronym in Portuguese: BHD) due to its high spatial resolution. Based on pedological maps of unitary cell areas from Assis/SP and Piracicaba/SP regions, the BHD was computed for 19 dekadal periods between 21 October 2004 and 29 April 2005, to determine the percentage of soil water availability (designated AD%) for each 1 km² cell. The mean areal rainfall for both Assis and Piracicaba, used as input to the BHD equation, was quantified in this different ways, e.g., based on rain gage through Thiessen polygon method and weather radar through an appropriate Z (radar reflectivity) to R (rainfall intensity) conversion relationship. Radar data were from the CAPPI (Constant Altitude Plan Position Indicator) product covering an area of 240 km range, at a 3,5 km (agl) height, generated each 7,5 or 15 minutes from the observations of the Doppler S band weather radar operated by IPMet/ UNESP in Bauru-SP. Date were processed to provide rainfall accumulations over dekadal periods for radar pixels at 1 x 1 km² resolution. To evaluate the spatial behavior of the radar derived rainfall, the Trend Surface Analysis technique was employed with a first degree polynomial regression in a grid model of 51 x 51 dimension, elaborated with the version v.7 of the SURFER® program aiming to map and identify the positive (excess rainfall) and negative (rainfall deficit) residuals in the Assis and Piracicaba regions. BHD effected with rain gage data, and with radar data provided different results for the maps of available water distribution for both regions. In the BHD based in rain gage a more homogenous pattern is perceived in the AD distribution as compared to the BHD computed with radar observations where results show a more heterogeneous rainfall distribution.
The present research was carried out with the aim of assessing and comparing the performance of an specific water balance process, denominated Distributed Water Balance (acronym in Portuguese: BHD) due to its high spatial resolution. Based on pedological maps of unitary cell areas from Assis/SP and Piracicaba/SP regions, the BHD was computed for 19 dekadal periods between 21 October 2004 and 29 April 2005, to determine the percentage of soil water availability (designated AD%) for each 1 km² cell. The mean areal rainfall for both Assis and Piracicaba, used as input to the BHD equation, was quantified in this different ways, e.g., based on rain gage through Thiessen polygon method and weather radar through an appropriate Z (radar reflectivity) to R (rainfall intensity) conversion relationship. Radar data were from the CAPPI (Constant Altitude Plan Position Indicator) product covering an area of 240 km range, at a 3,5 km (agl) height, generated each 7,5 or 15 minutes from the observations of the Doppler S band weather radar operated by IPMet/ UNESP in Bauru-SP. Date were processed to provide rainfall accumulations over dekadal periods for radar pixels at 1 x 1 km² resolution. To evaluate the spatial behavior of the radar derived rainfall, the Trend Surface Analysis technique was employed with a first degree polynomial regression in a grid model of 51 x 51 dimension, elaborated with the version v.7 of the SURFER® program aiming to map and identify the positive (excess rainfall) and negative (rainfall deficit) residuals in the Assis and Piracicaba regions. BHD effected with rain gage data, and with radar data provided different results for the maps of available water distribution for both regions. In the BHD based in rain gage a more homogenous pattern is perceived in the AD distribution as compared to the BHD computed with radar observations where results show a more heterogeneous rainfall distribution.
Descrição
Palavras-chave
Geofisica, Radar meteorológico, Meteorologia, Balanço hidrológico, Pluviometros, Water balance, Rain gage
Como citar
EMÍDIO, Zildene Pedrosa de Oliveira. Impacto do balanço hídrico em diferentes tipos de solos: comparação entre dados de radar-pluviômetro e análise de tendência da chuva em área agrícola. 2008. 147 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Geociências e Ciências Exatas, 2008.