A remote sensing model estimating water body evaporation

International water delivery management is a difficult issue. For example, according to the US and Mexico water delivery treaty, the US needs to deliver a certain amount of water from the Elephant Butte Reservoir (in US New Mexico state) to Mexico every year. Similarly, Mexico also needs to deliver a certain amount of water to the US each year. However, Mexico had amassed a water deficit to the US since 1992. The deficit reached 1.5 million acre-feet at its highest point, costing U.S. agricultural producers in the Rio Grande Valley $1 billion. Farmers in both countries complained to their government that the water provider country did not deliver enough water. Their government explained to the farmers that although the reservoirs had a certain level of inflow, the evaporation (E) loss was large enough to decrease the outflow significantly. Reservoir evaporation measurements from an inflow-outflow water balance method, pan measurement method, or eddy covariance methods are time and labor intensive. Additionally, the accuracy of the methods may be affected by environmental factors and some of their assumptions. There is a need to create an accurate and convenient method to measure the evaporation loss that can be used internationally. The research in this paper developed a remote sensing tool to estimate evaporation loss from reservoirs to aid international water delivery management. The model uses the energy balance principle to measure evaporation depth (mm/day). The evaporation depth has a high temporal resolution (1 day) and a moderate spatial resolution (1000 m by 1000 m). The model is written in C++ as a user-friendly software package. The model uses MODIS (Moderate Resolution Imaging Spectroradiometer) satellite data (LIB raw data) and local weather data (radiation, wind speed, and humidity). The model was calibrated and evaluated using reservoir data. The model accuracy is acceptable and is capable for aiding international water delivery management.