The Q&A: Yongli Gao

With each issue, Trib+Water brings you an interview with experts on water-related issues. Here is this week's subject:

Yongli Gao is the acting director of Center for Water Research and an associate professor at the Department of Geological Sciences at the University of Texas at San Antonio. He received a master's degree in computer science and a Ph.D. in hydrogeology from the University of Minnesota. His main research interests include karst hydrogeology and geomorphology, paleoclimate and paleoecology studies using speleothems and fossil records, GIS and database management in environmental investigations, assessments of sinkhole hazards and water resource, and basin-scale hydrologic simulations.

Editor's note: This interview has been edited for length and clarity.

Trib+Water: What does the role of acting director encompass for you and the center?

Yongli Gao: It is to make the Center for Water Research a catalyst and research leader for solving today’s — and future — water challenges. We also establish partnerships with entities in the San Antonio and Central Texas area.

We have research projects. In the past couple years, after I came here, it is is most focused on the local area: Bexar County, Comal County. We also partner with San Antonio Water System, Edwards Aquifer Authority.

 Trib+Water: What are the challenges that you are aiming to tackle?

Gao: A couple that are mostly related to the type of hydrology that is in area, the Edwards and Trinity Aquifer systems. Several of the challenges include surface water and groundwater interaction.

The Edwards and Trinity aquifers, we call them karst aquifer or carbonate aquifer. These usually have caves with conduit flow through the caves and also through the dissolved cavities or fractures so waters flow through aquifer very quickly. This type of aquifer can interact with surface water; in a lot of cases, very fast. That's not like the traditional aquifer. A lot of times, the flow velocity would be much slower, but in karst aquifer or carbonated aquifer, especially if it is well connected to the solution cavities, the flow can be really fast and contamination can spread out very quickly. 

So the challenge is to identify some of these features that have fast interactions with surface water or potential contamination.

Trib+Water: Are these issues that your partners are also interested in?

Gao: Yes, especially if there is is a sewage failure that can spread out into the carbonated aquifer very quickly, or a potential leak from an industrial site or municipal facilities.

Trib+Water: Does this research get implemented into San Antonio water policy or planning?

Gao: I’m not exactly sure, because we don’t work directly with a city office. Most of our work, especially related to this kind of research, is mainly for the scientific point of view.

I just started this kind of work here, but I used to also work on similar types of hydrogeology projects in other areas. Usually we don’t work directly with a city office or involving policy. We just provide what we find out from scientific research.

Trib+Water: Is the potential for contamination, along with the surface and ground water interaction, the major challenges? 

Gao: Another challenge would be still related to carbonated or karst aquifer. It is extremely difficult to study because they they are a heterogeneous system, so it is very complex. Part of the aquifer can be very highly permeable and have a very high flow velocity and part of the aquifer can be what we call a matrix, very slow, and there are some areas in between like fractures that connect conduits to matrix. Especially in the San Antonio segments of the Edwards and Trinity aquifer systems, and also the Balcones Fault zone, they displace the formation in areas, but also make the aquifer system extremely complex.

Trinity and Edwards are different formations. In some areas they might be separate, but in other areas they could be well connected. How these two aquifer formations interact with each other and also with surface water is poorly understood. That is another challenge that we are interested in studying, how the formations interact with each other and surface water.

Trib+Water: Why is it important to know more how they interact with each other?

Gao: The reason for that is a lot of the work in hydrology and hydrogeology involves modeling. Most of the time we only have a limited knowledge of a certain part of an aquifer system because you only have a limited number of wells. You can’t drill everywhere and those are the limited data we know. Most of the work will involve modeling, mathematical models of empirical models to tell us how the system works.

The problem in this type of karst system is that it is so complex, that it is a huge challenge for modeling.

Even though carbonate or karst systems are everywhere, different systems have their own complexities. Your study from one system may not work on another, like from Florida or the Midwest or the Appalachian karst areas where I used to work as a faculty member of East Tennessee State University. 

Trib+Water: Was the focus of the research different there than in Texas?

Gao: Another area of my research would be sinkhole hazards. I have studied many sinkhole hazards in karst in other areas but not much in this area.

It is not as severe of a hazard problem in the San Antonio or Austin area, but it is a huge problem in many other parts of the country, like Florida, Kentucky, Tennessee and Virginia. Also in Minnesota, where I did my Ph.D. Those areas have a lot of sinkholes. It is in part because of the landscape but it can also be because of human activities like pumping.

That is usually a main feature of karst areas. It is a hazard that can cause property damage or loss of life. There can also be a connection between the surface and an aquifer. So it can be a source of pollution. 

Trib+Water: Do you think the challenges the center is tackling on improving modeling and understanding the complexities, does that get the proper attention?

Gao: Definitely, it gets attention. There are many entities and communities that are involved at different levels to better understand and protect the water resources. What would be more important would be for different entities to communicate more frequently to know who is doing what.

If we can all work together and exchange ideas and share data; some state organizations have already been doing that, but the more we make these kind of efforts, in the long term it would help us to understand more. It would advance scientific research and help understanding of the system. And to apply that would help decision making for policy and planning to better protect water resources.