Environmental Engineering Reference
In-Depth Information
Chapter 13
Evapotranspiration Estimates from Remote
Sensing for Irrigation Water Management
Timothy C. Martin, Richard G. Allen, Larry E. Brazil,
J. Philip Burkhalter, and Jason S. Polly
Abstract
Climate change impacts and increasing demands on Morocco's water
resources present serious challenges to irrigation districts and water managers. Mod-
ernization of irrigation practices and delivery systems can help conserve water by
improving efficiencies and water productivity. Satellite imagery from Landsat and
MODIS and the METRIC surface energy balance method were used to derive
objective estimates of crop evapotranspiration (ET) in three Moroccan irrigation
sectors. The METRIC analysis requires satellite imagery with thermal (surface tem-
perature) information, as well as high-quality weather data. The spatially distributed
ET estimate maps were combined with surface water supply records and weather data
and used as inputs to a water balance analysis to estimate the quantity of supplemental
groundwater used for irrigation. The results are useful as a pre-project, baseline
condition for investments in irrigationmethods and system improvements. The remote
sensing data analysis provides useful results for large irrigated areas that have little
information on crop consumptive use and irrigation efficiency and almost no informa-
tion on groundwater abstraction. A similar approach can be used to monitor and assess
the system during and after the irrigation improvement project is completed.
Keywords
Evapotranspiration ET Remote sensing Energy balance Morocco
Irrigation Consumptive use METRIC
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