Estimación de evapotranspiración a escala regional a partir de imágenes Modis
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Date
2007
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Publisher
Universidad de Concepción
Abstract
Una buena estimación de la Evapotranspiración es primordial en los estudios hidrológicos, climatológicos, agronómicos y ecológicos. Para lograr este objetivo se utilizaron tres modelos para su estimación, a partir de las imágenes del sensor MODIS; Estos modelos se basan en la determinación de: Fracción de Evaporación (EF), Índice de Temperatura de Cubierta Vegetal (TVCI) y Resistencia Aerodinámica y de Canopia (). La Evapotranspiración estimada mediante las imágenes, fue comparada con los valores calculados usando los modelos de Penman – Monteith y Hargreaves La estimación es puntual sobre un pixel de 100 ha sin considerar el radio de influencia de la información que entrega la estación meteorológica, por lo que se consideró la diferencia media cuadrática (DCM). La temperatura ambiental estimada no considera el efecto orográfico y geomorfológico de la región, es por esto que es sobreestimada en la costa y subestimada en el valle central. De los modelos utilizados el TVCI y EF fueron los de menor DCM, debido a que TVCI considera de mejor manera la vegetación existente en la imagen, y EF sólo considera índice de vegetación y temperatura ambiental.
A good estimation of evapotranspiration is highly important for hydrological, climatological, agronomic and ecological research. To improve a methodology for ET estimation, at a regional scale, three models were develop to generate values based on the use of images captured by the sensor MODIS, mounted on the satellite Terra and Aqua. Those models are base on the determination of: Evaporation fraction (EF), Temperature vegetation cover index (TVCI) and aerodynamic and canopy Resistances(). The Evapotranspiration estimated through the images was compared with Penman – Monteith and Hargreaves - Samani. The estimation was made on a 100 ha resolution. The TVCI and EF models give a best mach, because TVCI incorporate in a better way the existent vegetation in the image, and the EF considers an index of vegetation and environmental temperature. The environmental estimated temperature, from Modis, does not consider the orographic effect and the geomorphology of the area, so temperature is overestimated at the coast and underestimated at the region Central Valley.
A good estimation of evapotranspiration is highly important for hydrological, climatological, agronomic and ecological research. To improve a methodology for ET estimation, at a regional scale, three models were develop to generate values based on the use of images captured by the sensor MODIS, mounted on the satellite Terra and Aqua. Those models are base on the determination of: Evaporation fraction (EF), Temperature vegetation cover index (TVCI) and aerodynamic and canopy Resistances(). The Evapotranspiration estimated through the images was compared with Penman – Monteith and Hargreaves - Samani. The estimation was made on a 100 ha resolution. The TVCI and EF models give a best mach, because TVCI incorporate in a better way the existent vegetation in the image, and the EF considers an index of vegetation and environmental temperature. The environmental estimated temperature, from Modis, does not consider the orographic effect and the geomorphology of the area, so temperature is overestimated at the coast and underestimated at the region Central Valley.
Description
Tesis presentada para optar al título de Ingeniero Civil Agrícola
Keywords
Evapotranspiración, Cubierta vegetal, Agricultura de precisión - Chile