Satellite-based evapotranspiration and crop coefficient for irrigated sorghum in the Gezira scheme, Sudan

M. A. Bashir (1) , T. Hata (1) , A. W. Abdelhadi (2) , H. Tanakamaru (1) , A. Tada (3)

1 Dept. of Food Systems and Field Sciences
2 Agricultural Research Corporation
3 Faculty of Agriculture

The availability of the actual water use from agricultural crops is considered as the key factor for irrigation water management, water resources planning, and water allocation. Traditionally, evapotranspiration (ET) has been estimated in the Gezira scheme by multiplying the reference evapotranspiration (ET_o) by crop coefficient (k_c) which is derived from the phenomenological crop stages. Recently, advanced developed energy balance models assist to estimate ET through remotely sensed data. In this study Enhanced Thematic Mapper Plus (ETM+) images were used to estimate spatial distribution of daily, monthly and seasonal ET for irrigated sorghum in the Gezira scheme, Sudan. The daily ET maps were also used to estimate k_c over time and space. Results of remotely sensed based energy balance were compared with actual measurements conducted during 2004/05 season. The daily actual ET values estimated using the energy balance model during the satellite acquisition dates (28 July, 29 August, 16 October and 17 November) were 4.7, 5.5, 7.1 and 2.7 mm/day, while the average seasonal evapotranspiration for irrigated sorghum estimated to be around 596 mm. The remotely estimated k_c values in the initial, crop development, mid-season and late-season stages were 0.62, 0.85, 1.15, and 0.48 respectively. On the other hand the widely used tradition k_c values during the pervious mention stages are 0.55, 0.94, 1.21 and 0.65, respectively. This research shows that remotely sensed measurements can help objectively analyzed the irrigation water requirement for different field crops on daily and seasonal time step. Moreover, the remotely sensed real-time data availability provides the system managers with information that not previously available.

Domaines: Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

M. A. Bashir, T. Hata, A. W. Abdelhadi, H. Tanakamaru, A. Tada. Satellite-based evapotranspiration and crop coefficient for irrigated sorghum in the Gezira scheme, Sudan. Hydrology and Earth System Sciences Discussions, 2006, 3 (3), pp.793-817. ⟨hal-00298697⟩