Learnings from a Life Experiment of Irrigation Preconization by Remote Sensing in Morocco.
Le Page, Michel1; Khabba, Saïd2; Jarlan, Lionel3; Er-Raki, Salah2; Kharrou, Hakim4; Tavernier, Adrien5; Simonneaux, Vincent3; Hagolle, Olivier3; Chehbouni, Abdelghani5

In southern Mediterranean region, as well as other arid and semi-arid regions in the world, water consumption has significantly increased over the last decades, while available water resources are becoming increasingly scarce. In Morocco, irrigation is highly water demanding: it is estimated that 83% of available resources is dedicated to agriculture with an efficiency lower than 50%. The Haouz region, typical of southern Mediterranean basins, is characterized by a semi-arid climate (the potential evapotranspiration is about 1600 mm/year against an average annual rainfall of 250 mm) [5]. Under these conditions, crop irrigation is inevitable for growth and development. In this situation, and to preserve water resources, the rational management of water irrigation is necessary.

Water demand of crops mainly depends on two aspects: meteorological conditions and crop development. Many researches have demonstrated that optical and thermic imagery from earth observation satellites offer a precise input to estimate the state of crops. Associated with an hydric budget and some forecasting aspects (meteo, plant development), the remotely sensed information can be very helpful for the decision maker of irrigation. In order to obtain the more crops for a drop, plant stress must be avoided as far as possible so that the yield won't be affected. On the other side, excessive quantities of water, that would be finally lost for the plant, must also b avoided.

During the winter wheat season of 2013, a live experiment is taking place, comparing common strategy of irrigation to a Remote Sensing guided strategy of irrigation on a 4 hectareas test site located in the surroundings of Marrakech, Morocco. The experiment benefits from the swan song of SPOT4 satellite which consists in providing a high resolution image each 5 days, a space and time resolution very close to SENTINEL-2.

The first results of the experiment are convincing on evapotranspiration estimations compared to flux tower measurements (rmse=0.4mm/day). The irrigation recommendations suggested by the model are performed on the field by the collaborating farmer.
Several learnings are coming out of the life experiment. In particular, practical aspects of implementation are unveiled (telemetry, imagery repetitivity,...) while some indices about the social acceptance of such a technology are identified like simplicity and flexibility.