The past few weeks have highlighted a challenge for water resource managers in Texas: We either have too much water when we don’t need it or too little when we do.
What is obvious is that the recent floods were devastating and underscores the need to be better prepared in not only monitoring, but also keeping as much of that water as possible.
One of the primary approaches for managing water resources for these extremes is to store water from times of excess for use during droughts. Traditional approaches for storing water are surface reservoirs, but unfortunately the rate that we built new reservoirs has slowed dramatically since the 1970s while our population has about doubled since that time, resulting in halving the per capita reservoir storage since the peak in the 1970s.
Therefore, we have less storage buffer in the system now than we did in the 1970s. The prime locations for surface water reservoirs have already been developed, and getting permits for new reservoirs is challenging and expensive. So what should we do?
Instead of storing excess water on the surface where it can evaporate, particularly during droughts, we should increase the use of storing excess surface water underground in aquifers using “Aquifer Storage and Recovery,” or ASR.
The San Antonio Water System has been doing this since 2004, storing water from the Edwards Aquifer during times of excess in the Carrizo Aquifer. This storage was very beneficial for San Antonio, particularly during the 2011 drought.
There are many more opportunities as well as capacity for doing ASR across the state, and such storage would complement surface reservoirs and off-channel reservoirs.
The Texas Legislature, particularly state Rep. Lyle Larson, is a strong advocate of this approach, and House Bill 655 should advance the application of ASR in the state. The bill allows a water right holder to use water from existing permits, such as reservoir storage during a flood, for ASR without the need for an amendment. The bill was recently signed by Gov. Greg Abbott.
This is a good first step, but we can do more.
Excess water during flooding could be transferred to aquifers for long-term storage. The heavily depleted Trinity Aquifer near Dallas provides a huge potential storage reservoir for ASR. During the recent heavy rains in Central Texas, excess surface water could have been stored in the saline portions of the Edwards Aquifer in Austin for later use.
Rainwater harvesting is another approach that is expanding, with more households installing systems for nonpotable water use, including lawn watering. The Texas Water Development Board estimates that the City of Austin could collect approximately 32,000 gallons of water per house annually (with a 2,000 sq. ft. roof) using rainwater harvesting, and Austin incentivizes rainwater harvesting through its rebate program.
While storage seems to be one of the key approaches to managing the extremes, monitoring these extremes is also critical. As we saw in recent news reports of the flooding along the Blanco River, the existing monitoring program was inadequate.
We should expand the current monitoring program by considering citizen science and community-based monitoring. When and where flooding will happen is extremely difficult to predict. However, citizen smartphones represent a large number of eyes that can inform disaster management programs if we develop approaches for handling the data.
Water is one of our most precious resources, and although the recent floods have been devastating, we can learn from these disasters by expanding water storage in the state, improving monitoring programs and being better prepared in the future.
Bridget Scanlon is a senior research scientist in the Bureau of Economic Geology at The University of Texas at Austin.
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