Modelling of Actual Crop Water Consumption Using Airborne and Optical-Thermal Satellite Data over Murrumbidgee Catchment
M. Hafeez, S. Khan, K. Song, U. Rabbani and J.P. Walker
Spatial knowledge of land surface evapotranspiration is of prime interest for environmental applications, such as optimizing irrigation water use, especially in arid and semiarid catchments where water shortage is a critical problem. This study examines the components of the surface energy balance in the Murrumbidgee catchment as part of the National Airborne Field Experimentation (NAFE) project conducted over a month in November 2006. The study areas are Yanco creek and Kyeamba creek located in Murrumbidgee cacthment. Instruments like a thermal imager and a tri-spectral scanner was flown onboard a small environmental research aircraft at different altitudes together with coincident ground data collection on soil moisture, surface roughness, skin and soil temperature, and vegetation water content. Optical-Thermal satellite images like Terra/ASTER, Landsat, and Terra/MODIS covering the same time period over Yancoo and Kyeamba creek were acquired to solve energy balance. Several algorithms were applied to solve energy balance from airborne and optical-thermal satellite data. The results of those algorithms were compared to figure out possible deviations in actual evapotranspiration measurements. This paper solves partitioning of energy balance using airborne and satellite data for the same day. Similarly, Eddy Covariance flux tower was also installed at Kyeamba creek near Wagga Wagga which was used to validate the actual evapotranspiration estimated from airborne campaign and optical-thermal satellites. Results show a good correlation of values of evapotranspiration measured from airborne and satellite data. Finally an error matrix and possible reasons of small deviations in measurement of actual crop water consumption at different spatial scales are discussed.