SAM-ET model development at 10cm spatial resolution from a UAV

Very high spatial resolution evapotranspiration (ET) estimation by close range remote sensing is as important for agricultural production as it is to irrigation infrastructure leakage detection. Unmanned Aerial Vehicles (UAV) are becoming a common research and monitoring tool in agricultural and horticultural crops monitoring World-wide. Our UAV has been operating in irrigation systems for several years now, and we are developing energy balance and thermodynamic flux modeling from its produced imagery which is comparable to Landsat satellite, albeit the spatial resolution which is at about 10cm. This paper is concentrating on the recent enhancements of our UAV to increase position and attitude recording, and the developments of an adaptation of the SAM-ET model to estimate ET from the on-board sensors, a multispectral sensor and a thermal infrared sensor. Questions of radiometric calibration of images will be tackled with specifically designed reflective boards, while geometric corrections are still minimal. Development of a processing chain system involves multi-disciplanry effort since it all starts in automation process at hardware communication level. A several steps approach is followed, with isolation of few parts initially, before merging them as one chain from hardware, to software, to RS product delivery. The question of time to delivery is also under close scrutiny too, as irrigation system monitoring requires a fast feed-back to farmers through our web service, meaning to real-time processing.