The groundwater-surface water connection

Sharlene Leurig:

We dug through a ton of data to learn what we could about how much water in Texas rivers comes from groundwater. We were really amazed to find that in an average year, not a drought year, anywhere between 15 and 40 percent of a river’s flow comes from the water below ground.

During times of drought, like what we have been experiencing in the past few years, the amount of water in a river in Texas that comes from below ground can be as high as 80 percent of total flow. So it is a really critical interaction, but it is one that is poorly understood in terms of data and monitoring. It is poorly managed in terms of state water plans, projections of future availability, the impact of our desired future conditions.