WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2005ID54B
Title: Evaluation of remote sensing of leaf area index for estimating evapotranspiration on irrigated lands
Project Type: Research
Focus Categories: Irrigation, Management and Planning, Water Quantity
Keywords: Evapotranspiration, Remote Sensing, Irrigation, Leaf Area Index
Start Date: 03/01/2005
End Date: 02/28/2005
Federal Funds: $18,997
Non-Federal Matching Funds: $35,064
Congressional District: 01
Evapotranspiration is a major component of basin water budgets and consequently knowledge of this feature is essential to studies and planning of water management. For example, in the eastern Snake River Plain, estimates of evapotranspiration (ET) were used to represent the consumptive portion of ground water irrigation pumping in an aquifer model and in applications of that model to determine effects of pumping on spring discharge. ET estimates are often used in water balance analyses to determine lesser known components such as aquifer recharge.
Remote sensing can be a valuable tool in estimating evapotranspiration on large scales due to the high areal variability of ET. In previous work, algorithms such as SEBAL and METRIC have made use of the thermal bands of LANDSAT data in energy balance calculations of ET. The continued use of these tools is in jeopardy due to the planned discontinuation of distribution of the thermal band of data from LANDSAT.
The purpose of this project is to develop and evaluate an alternative means of determining the areal distribution of irrigated ET from visible and near-infrared bands from LANDSAT. The project would use an existing Normalized Difference Vegetative Index as a proxy for leaf area index and develop a relationship between this index and crop coefficients (e.g. the ratio of ET for a specific crop and field and reference ET). The Index would be calibrated to SEBAL determined crop coefficients for specific fields and periods. The accuracy of the resulting relationship would be determined by application to a test data set with results compared against SEBAL estimated ET. The cost and time requirement for application would be evaluated to help assess the potential for practical application of the method.
If the project is successful, it will result in the development of a method to replace existing remote sensing algorithms when the thermal band is no longer available. Success of this project may also result in subsequent related studies for remote sensing of ET from non-irrigated areas.