Calibración de los coeficientes de corrección del modelo de Hargreavez-Samani para la región de Ñuble, Chile
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Date
2025
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Universidad de Concepción
Abstract
El método de Hargreaves-Samani (H-S) fue aplicado para calcular la evapotranspiración de referencia (ETr) en ocho distritos agroclimáticos de la región de Ñuble, Chile. El estudio se centró en calibrar los coeficientes de corrección del modelo de H-S (α y β), con el propósito de adaptar su uso a las características específicas de la región. La calibración se realizó en función de la ETr obtenida desde el modelo de Penman-Monteith (P-M) para un cultivo de pasto corto. Para ello, se utilizaron datos diarios de temperatura, humedad relativa, radiación solar y velocidad de viento de las estaciones de Santa Rosa, Ninhue, Portezuelo, Yungay, Sauzal, Chanco, Bulnes y Monte Blanco - Tucapel, cubriendo un intervalo de tiempo de 14 años (2009-2023). Los resultados mostraron que los coeficientes α y β variaron entre 0,1428 y 0.00537 en zonas cordilleranas, mientras que en el valle central oscilaron entre 0,1235 y 0.00667, respectivamente. Con la corrección de α y β se encontraron R2 y RMSE promedios de 0,81 y 1,30 mm dia-1, mientras que para zonas más cercanas a la costa, como Chanco, los valores de R2 aumentaron en un 1,81% y el RMSE disminuyó un 50% en comparación con los valores promedios. Finalmente este enfoque permite determinar la ETr en áreas donde el acceso a datos meteorológicos detallados es limitado con una correlación promedio mayor al 80%. Se espera que futuros desarrollos se enfoquen en incorporar estimaciones de ETr en una aplicación móvil para pronosticar la demanda de agua de cultivos y frutales a 1, 3 y 5 días, lo que permitirá programar el manejo de riego futuro en la región de Ñuble.
The Hargreaves-Samani (H-S) method was applied to calculate the reference evapotranspiration (ETr) in eight agroclimatic districts of the Ñuble region, Chile. The study focused on calibrating the correction coefficients of the H-S model (α and β) to adapt its application to the specific characteristics of the region. Calibration was conducted based on the ETr obtained from the Penman-Monteith (P-M) model for a short grass crop. Daily data on temperature, relative humidity, solar radiation, and wind speed were utilized from the stations of Santa Rosa, Ninhue, Portezuelo, Yungay, Sauzal, Chanco, Bulnes, and Monte Blanco - Tucapel, covering a time span of 14 years (2009-2023). The results indicated that the coefficients α and β varied between 0.1428 and 0.00537 in mountainous areas, while in the central valley, they ranged from 0.1235 to 0.00667, respectively. With the correction of α and β, average R² and RMSE values of 0.81 and 1.30 mm day⁻¹ were obtained. In coastal areas such as Chanco, the R² value increased by 1.81%, and the RMSE magnitude decreased by nearly 50% compared to the average values. Ultimately, this approach enables the determination of ETr in regions where access to detailed meteorological data is limited, achieving an average correlation greater than 80%. Future developments are expected to focus on incorporating ETr estimates into a mobile application to forecast (1, 3, and 5 days) the water demand of crops and fruit trees, facilitating the scheduling of future irrigation management in the Ñuble region.
The Hargreaves-Samani (H-S) method was applied to calculate the reference evapotranspiration (ETr) in eight agroclimatic districts of the Ñuble region, Chile. The study focused on calibrating the correction coefficients of the H-S model (α and β) to adapt its application to the specific characteristics of the region. Calibration was conducted based on the ETr obtained from the Penman-Monteith (P-M) model for a short grass crop. Daily data on temperature, relative humidity, solar radiation, and wind speed were utilized from the stations of Santa Rosa, Ninhue, Portezuelo, Yungay, Sauzal, Chanco, Bulnes, and Monte Blanco - Tucapel, covering a time span of 14 years (2009-2023). The results indicated that the coefficients α and β varied between 0.1428 and 0.00537 in mountainous areas, while in the central valley, they ranged from 0.1235 to 0.00667, respectively. With the correction of α and β, average R² and RMSE values of 0.81 and 1.30 mm day⁻¹ were obtained. In coastal areas such as Chanco, the R² value increased by 1.81%, and the RMSE magnitude decreased by nearly 50% compared to the average values. Ultimately, this approach enables the determination of ETr in regions where access to detailed meteorological data is limited, achieving an average correlation greater than 80%. Future developments are expected to focus on incorporating ETr estimates into a mobile application to forecast (1, 3, and 5 days) the water demand of crops and fruit trees, facilitating the scheduling of future irrigation management in the Ñuble region.
Description
Tesis presentada para optar al título de Ingeniero Civil Agrícola
Keywords
Evapotranspiración - Chile - Chillán, Manejo de suelos, Riego - Administración