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Abstract
One of the most important parameter of climatic water balance computation is crop coefficient (Kc). Unfortunately, the Kc is one of the most difficult parameter to measure in the field. This paper attempts to determine the crop coefficient by using climate observation data and the NDVI (Normalized Difference Vegetation Index) derived from NOAA (National Oceanic and Atmospheric Administration). Calculation using Morton’s Complementary Relationship Areal Evapotranspiration (CRAE) method that used elevation (m), annual precipitation (mm), monthly air temperature ( C), sunshine duration (%), as minimum requirement data, has been applied for more than 900 climatic stations over the Asian region that well documented by FAO-CLIM agroclimatic database to obtain the Kc value. The result was then related to NDVI derived from spectral reflectance of NOAA/AVHRR data. The relation results of NDVI and crop coefficient gave significant linear equation as Kc = 0.08 + 1.83 NDVI, with average correlation coefficient 0.72. It was high over humid area such as in Java island of Indonesia; on the other hand, it was low in semi arid area, such as west part of India. Even the results above were fit only for a specified area; this study has demonstrated a potential use of NOAA image for supplying the crop coefficient value that would be particularly necessary to determine actual evapotranspiration.
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References
- Allen, R.G., L.S. Pereira, D. Raes, and M. Smith. 1998. Crop Evapotranspiration: Guidelines for computing crop water requirements. Irrigation and Drainage Paper 56, Food and Agriculture Organization of the United Nations, Rome
- Choudhury, B.J. 1997. Global pattern of potential evaporation calculated from the Penman Monteith equation using satellite and assimilated data, Remote Sens. Environ., 61:64-81.
- Doorenbos, J., and Pruitt, W. O. 1977. Guidelines for predicting crop water requirement, FAO Irrigation and Drainage Paper 24. FAO Rome, Italy.
- Heilman, J.L., Heilman, W.E. and Moore, D.G. 1982. Evaluating the crop coefficient using spectral reflectance. Agron. 74: 967-871.
- Jensen, M. E., Burman, R. D., and Allen, R. G. 1990. Evaporation and Irrigation Water Requirement, ASCE Manual No. 70, American Society of Civil Engineers, New York
- Kondoh A., 1994. The comparison of evapotranspiration in Monsoon Asia by different methods.J. Japan Assoc. Hydro logical Sciences, 24, 11-30. (in Japanese with English Abstract)
- Morton, F.I. 1983. Operational estimates of areal
- evapotranspiration and the significance to the science and practice of hydrology, J. Hydrology, 66: 1-76.
- Salazar, L. F and G. Poveda. 2006. Validation of Diverse Evapotranspiration Estimation Methods using the Long-term Water Balance in the Amazon River Basin. p. 815-820. Proceedings of 8 ICSHMO, Foz do Iguaçu, Brazil, April 24-28, 2006, INPE,
- Testi, L., Villalobosa F. J., and Orgaza F. 2004. Evapotranspiration of a young irrigated olive orchard in southern Spain. Agricultural and Forest Meteorology, Issues 1-2, 121: 1-18.
- Williamsa, L.E, and Ayarsb J.E. 2005. Water use of Thompson Seedless grapevines as affected by the application of gibberellic acid (GA3) and trunk girdling – practices to increase berry size. Agricultural and Forest Meteorology, Issues 1-2, 129: 85-94.
References
Allen, R.G., L.S. Pereira, D. Raes, and M. Smith. 1998. Crop Evapotranspiration: Guidelines for computing crop water requirements. Irrigation and Drainage Paper 56, Food and Agriculture Organization of the United Nations, Rome
Choudhury, B.J. 1997. Global pattern of potential evaporation calculated from the Penman Monteith equation using satellite and assimilated data, Remote Sens. Environ., 61:64-81.
Doorenbos, J., and Pruitt, W. O. 1977. Guidelines for predicting crop water requirement, FAO Irrigation and Drainage Paper 24. FAO Rome, Italy.
Heilman, J.L., Heilman, W.E. and Moore, D.G. 1982. Evaluating the crop coefficient using spectral reflectance. Agron. 74: 967-871.
Jensen, M. E., Burman, R. D., and Allen, R. G. 1990. Evaporation and Irrigation Water Requirement, ASCE Manual No. 70, American Society of Civil Engineers, New York
Kondoh A., 1994. The comparison of evapotranspiration in Monsoon Asia by different methods.J. Japan Assoc. Hydro logical Sciences, 24, 11-30. (in Japanese with English Abstract)
Morton, F.I. 1983. Operational estimates of areal
evapotranspiration and the significance to the science and practice of hydrology, J. Hydrology, 66: 1-76.
Salazar, L. F and G. Poveda. 2006. Validation of Diverse Evapotranspiration Estimation Methods using the Long-term Water Balance in the Amazon River Basin. p. 815-820. Proceedings of 8 ICSHMO, Foz do Iguaçu, Brazil, April 24-28, 2006, INPE,
Testi, L., Villalobosa F. J., and Orgaza F. 2004. Evapotranspiration of a young irrigated olive orchard in southern Spain. Agricultural and Forest Meteorology, Issues 1-2, 121: 1-18.
Williamsa, L.E, and Ayarsb J.E. 2005. Water use of Thompson Seedless grapevines as affected by the application of gibberellic acid (GA3) and trunk girdling – practices to increase berry size. Agricultural and Forest Meteorology, Issues 1-2, 129: 85-94.