The Texas Water Development Board has published the second installment of an “Ask an Expert” series in which agency hydrologist Dr. Mark Wentzel answers common questions about the reservoir data featured on the state’s Water Data for Texas dashboard.
The dashboard, managed by the TWDB, brings together real-time information on reservoirs, aquifers, rainfall and evaporation, giving Texans a way to track water supplies and understand changing conditions.
In the July 15 article, Wentzel explained why reservoirs behave differently across the state. He compared reservoirs to a bank account, storing water in times of plenty for use in times of scarcity. East Texas reservoirs, fed by more consistent rainfall, typically decline in summer but recover later in the year except during extreme drought, he said, while West Texas reservoirs receive less frequent inflows and may refill only every few years.
Wentzel said the same storage level can mean very different things depending on location. A drop to 50 percent of capacity would mark a nearly 40-year low for Fort Worth’s surface-water reservoirs, which have averaged 91 percent since 1990, he noted, but the same level would represent relatively plentiful conditions for the Lubbock system, which has averaged 39 percent.
He also described the natural lag between rainfall, runoff and reservoir inflow, explaining that recovery can take months in humid East Texas and years in the arid regions of West and South Texas, though a single large rainfall event can refill a reservoir in days.
Looking ahead, Wentzel said advances in remotely sensed data and greater computing power are enabling more detailed reservoir monitoring, and may eventually make it possible to track smaller, ungauged lakes and reservoirs across Texas using satellite data.