Evapotranspiration (ET) is an essential component of the water balance. Any attempt to improve water use efficiency must be based on reliable estimates of ET, which includes water evaporation from land and water surfaces and transpiration by vegetation. ET varies regionally and seasonally according to weather and wind conditions. Remote sensing based agro-meteorological models are presently most suited for estimating crop water use at both field and regional scales. Numerous ET algorithms have been developed to make use of remote sensing data acquired by sensors on airborne and satellite platforms. The use of remote sensing to estimate ET is presently being developed along two approaches: (a) land surface energy balance (EB) method and (b) Reflectance based crop coefficient and reference ET approach. The reported estimation accuracy varied from 67 to 97% for daily ET and above 94% for seasonal ET indicating that they have the potential to estimate regional ET accurately. Automated contours are not confined to specific pre-determined geographic areas (as in MLRA), require less time and cost. The spatial and temporal remote sensing data from the existing set of earth observing satellite platforms are not sufficient enough to be used in the estimation of spatially distributed ET for on-farm irrigation management purposes, especially at a field scale level (~10 to 200 ha). However, research opportunities exist to improve the spatial and temporal resolution of ET by developing algorithms to increase the spatial resolution of reflectance and surface temperature data derived from K1VHRR/Landsat/ASTER/MODIS images using same/other-sensor high resolution multi-spectral images.
Algorithms, Evapotranspiration, Radiometric, Radiation, Remote sensing
Brochet, P. and Gerbier, N. (1972). Une methode pratique de calcul de lâ€™hapotranspiration potentielle. Annales Agronomiques, 23(1), 31-49.
ChaÂ´vez J.L. and Neale, C.M.U. (2003). Validating airborne multispectral remotely sensed heat fluxes with ground energy balance tower and heat flux source area (footprint) functions. ASAE Paper No. 033128. St. Joseph, Michigan.
Chiew, F., Wang, Q.J., McConachy, F., James, R., Wright, W. and deHoed, G. (2002). Evapotranspiration maps for Australia. Hydrology and Water Resources Symposium, Melbourne, 20-23 May, Institution of Engineers, Australia.
Church, M.R., Bishop, G.D. and Cassell, D.L. (1995). Maps of regional evapotranspiration and runoff/precipitation ratios in the northeast United States. Journal of Hydrology 168: 283-298.
Droogers, P., Immerzeela, W.W. and Lorite, I.J. (2010). Estimating actual irrigation application by remotely sensed evapotranspiration observations. Agricultural Water Management, 97: 1351â€“1359.
Merkoci, A. L., Gjata, G., Bogdani, M. N., Dvorani, M. and Shkurti, E. (2010). An approach to mapping evapotranspiration by meteorological element with application to the territory of Albania. International Conference SDI â€“ Skopje.
Morton, F.I. (1983). Operational estimates of areal evapotranspiration and their significance to the science and practice of hydrology, Journal of Hydrology, 66: 1-76.
Najjar, G., Arnbroise, B. and Mercier, J.L. (1981). Measurement and mapping of potential evapotranspiration in a small mountainous watershed. Nordic Hydrology, 195-206.
Norman, J.M., Kustas, W.P and Humes, K.S. (1995). A twosource approach for estimating soil and vegetation energy fluxes from observations of directional radiometric surface temperature. Agricultural Forest Meteorology, 77: 263â€“293.
Rouse, J.W., Haas, R.H. Jr., Schell, J.A. and Deering, D.W. (1974). Monitoring vegetation systems in the Great Plains with ERTS. In: Proceedings of the ERTS-1 3rd Symposium, vol 1. NASA SP-351. NASA, Washington, pp 309â€“317.
Todd, R.W., Evett, S.R and Howell, T.A. (2000). The Bowen ratio-energy balance method for estimating latent heat flux of irrigated alfalfa evaluated in a semi-arid, advective environment. Agricultural Forest Meteorology, 103:335â€“348.
This work is licensed under Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) © Author (s)