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Sudan Journal of Agricultural Research
Monitoring evapotranspiration using remote sensing: application possibilities and future prospects
Bashir M. A. , H. Tanakamaru and A. Tada
Abstract:
The availability of actual water use from agricultural crops is considered
as the key factor for irrigation water management, water resources planning,
and water allocation. Estimating the crop water demand is important for
adequate water management in semi-arid areas where irrigation is necessary
and water is quite expensive. In many parts of the world, the available
water resources are presently being tapped close to the limit, thus the
provision and the sustainable management of water are of paramount
importance. The assessment and management of water resources requires
accurate measurements of evapotranspiration (ET). Most conventional
techniques that use point measurements to estimate ET are representative
only of local areas and can not be extended to large areas because of the
dynamic nature and regional variation of ET. Remote sensing techniques,
which provide a global and almost continuous dataset, have a potential for
use in monitoring regional ET. In recent years, many models/algorithms for
monitoring ET using remotely sensed data have been developed and evaluated
with a few selected dataset. These models need to be evaluated in the Sudan
in order to assess their potential applicability in estimating ET. In this
study a satellite-based model known as SEBAL was used to estimate the
spatial distribution of ET and surface energy exchange over the Gezira
scheme using satellite measurements and ground observations. The daily and
seasonal ET values were compared to the actual measurements in the field.
The derived crop coefficients from remotely sensed data were used to
calculate crop water requirement of sorghum. The results depict that
satellite-based method and data from remote sensing can be used effectively
for estimating CWR as well as crop coefficient values for irrigated crops in
the Gezira scheme.
Sudan Journal of Agricultural Research Vol. 10 (2007) PP. 59-71
