Articles
REMOTE SENSING OF IRRIGATION REQUIREMENTS IN WINE GRAPES; VALIDATION OF AN ENERGY BALANCE MODEL AND POTENTIAL APPLICATION OF VEGETATION INDICES
Article number
1038_29
Pages
249 – 254
Language
English
Abstract
Field measurements of basal crop coefficients (Kc) were taken during the 2001 season in order to validate the energy balance algorithm at the land level (SEBAL) in multiple commercial vineyards located within the Central Valley of California.
For this purpose, we used estimates of crop coefficients (ETa/ETo), basal crop coefficients (ETp/ETo), and NDVI, all derived by SEBAL North America from Landsat TM 5 images collected at different times during the growing season.
Since vineyard evapo-transpiration (ETa) is affected by the interaction between irrigation levels and atmospheric demand we focused on potential water use (ETp) and basal crop coefficients (Kc=ETp/ETo). The basal crop coefficients obtained from SEBAL were compared with field measurements of potential water use collected over several locations in multiple commercial vineyards.
The results showed a very good accuracy of the SEBAL model (error +/- 5% across multiple vineyards and varieties).
We also looked at the relationship between basal crop coefficients and NDVI, and then studied the link between NDVI and vineyard parameters such as yield, and soluble solids.
NDVI and basal crop coefficients for almost two hundred commercial vineyards were analyzed covering a very wide range of the two variables, which were found to be highly correlated (r2>0.95) However, NDVI did not correlate very well with either yield or fruit composition variables such as soluble solids.
For this purpose, we used estimates of crop coefficients (ETa/ETo), basal crop coefficients (ETp/ETo), and NDVI, all derived by SEBAL North America from Landsat TM 5 images collected at different times during the growing season.
Since vineyard evapo-transpiration (ETa) is affected by the interaction between irrigation levels and atmospheric demand we focused on potential water use (ETp) and basal crop coefficients (Kc=ETp/ETo). The basal crop coefficients obtained from SEBAL were compared with field measurements of potential water use collected over several locations in multiple commercial vineyards.
The results showed a very good accuracy of the SEBAL model (error +/- 5% across multiple vineyards and varieties).
We also looked at the relationship between basal crop coefficients and NDVI, and then studied the link between NDVI and vineyard parameters such as yield, and soluble solids.
NDVI and basal crop coefficients for almost two hundred commercial vineyards were analyzed covering a very wide range of the two variables, which were found to be highly correlated (r2>0.95) However, NDVI did not correlate very well with either yield or fruit composition variables such as soluble solids.
Authors
M. Mendez-Costabel, A. Morgan, N. Dokoozlian, B. Thoreson, B. Clark
Keywords
NDVI, basal crop coefficients, water
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