Scientists from Texas A&M University, led by Dr. Huilin Gao and Dr. Bingjie Zhao, have developed a new method for estimating daily reservoir evaporation rates. This research, detailed in the journal Water Resources Research, highlights the importance of accurate evaporation estimates for managing water resources, especially in Texas where summer temperatures can exceed 100 degrees.
Dr. Nelun Fernando from the Texas Water Development Board emphasized that this method “will enhance decision-making processes related to reservoir operations, water rights allocation, and long-term water planning in Texas and beyond.” The algorithm uses standard meteorological data such as wind, temperature, and relative humidity to simplify calculations for each reservoir.
Traditional methods rely on Class A Evaporation Pans to estimate evaporation by measuring changes in water level. However, these pans are often located away from reservoirs and do not account for factors like wind or temperature differences between air and water. Zhao pointed out that “the lakes are much deeper than the evaporation pans,” which leads to discrepancies in predicted evaporation rates.
Currently applied only to Texas reservoirs, the algorithm has shown a clear geographic distribution and seasonality of evaporation across the state. It also indicates an upward trend in evaporation rates at about 1.1 inches per decade.
The study was co-authored by researchers from multiple institutions including Desert Research Institute (DRI), Lower Colorado River Authority (LCRA), U.S. Army Corps of Engineers (USACE) – Dallas-Fort Worth District, and U.S. Bureau of Reclamation. Due to its success in Texas, the team is expanding their work to cover major reservoirs throughout the western United States.
