Meg Riley
Summary
Andrea Tavera, a former University of Oklahoma graduate student, used Innovyze drainage design software to promote LID-based, green infrastructure design in hopes of resolving Oklahoma’s two greatest drainage challenges caused by stormwater runoff: excessive flooding and pollution.
Efficient drainage design
A master’s student, Andrea Tavera focused her thesis on the evaluation of Low Impact Development (LID) and stormwater control systems for peak flow reduction. She was interested in how implementing LID techniques, through efficient drainage design, could help Oklahoma City and Tulsa improve their water quality and prevent the worst impacts of floods.
Following the 2017 flood in her home country of Colombia, Tavera grew passionate about finding a better way to reduce flood in other communities, to prevent others from suffering a similar tragedy. During her studies at University of Oklahoma, she worked with professor Dr. Jason Vogel to design LID models. They believed LID was most effective for reducing peak flow during heavy rainfall, thereby preventing flooding.
When Tavera took on this project for her thesis, her objectives were to:
- Model and design optimized LID practices for flood peak reduction for neighborhoods within Oklahoma City and Tulsa
- Compare model-simulated runoff water quantity and quality improvements within stormwater, to reduce pollutants
While exploring the potential of LIDs for peak flow reduction and total pollutant load reduction, she used the InfoDrainage stormwater model. “Felt like it was a good fit, though I had to learn modeling in InfoDrainage on-the-go as I was doing my thesis,” she says. “I really love the model feel.”
Flooding with challenges
“Urban flooding generally happens when heavy rainfall is immediately followed by a restricted drainage system capability. Flooding has been recurring from high-precipitation events and has been causing property damage, giving this investigation the opportunity to address and assess the issues related to the flooding and how to be able to mitigate them by modeling the current system and evaluating how LID is able to reduce peak runoff,” explains Tavera.
Stormwater creates two major challenges in the state of Oklahoma: flooding and pollution from stormwater. Additionally, harmful substances like oils, metals, pesticides, and bacteria make their way into the mix, presenting major water quality problems when they end up in rivers, lakes, and oceans. Stormwater leads to excess pollutants including Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN) pollutants. Tavera wanted to prove that LID could improve water quality and reduce those pollutants.
Using the InfoDrainage program, she input data collected from NOAA for rainfall, evaporation, and land cover. “My rainfall data came from NOAA, and to calibrate the flow in the outfall of one of the watersheds, I placed a pressure transducer in the concrete channel and collected data after a big storm to see how much flow would be present during a significant event.” Then, she received an output of runoff depth before and after LID implementation, allowing her to calculate the outcome of the design including cost.
Why you should choose LID
Low Impact Development (LID) seeks to reduce floods and water shortages, as well as improve water quality. “It is a site design strategy that aims to maintain, replicate, or minimize the change in the pre-development hydrologic conditions. It uses techniques that create functionally equivalent hydrologic landscapes as well as address maintenance for pollutant removal,” says Tavera.
The storm sewer system collects rainwater runoff, untreated waste, and an excess of Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN) pollutants. Unfortunately, those systems can often experience overflows because the water is going into a storm drain implanted into concrete that doesn’t drain properly. The volume of that wastewater exceeds the capacity of the system during heavy rainfall, which residents of Oklahoma experience regularly.
LID uses an underdrain system beneath the earth to drain water into grass, thereby avoiding water buildup. It’s green infrastructure; it prefers natural catchments over its concrete counterpart and utilizes stormwater as a resource. With LID design, Tavera could reduce inundation of Oklahoma’s traditional stormwater drainage networks and help mitigate flood risks, but with an environmentally sensitive approach.
It’s also preferred over other design methods for those who wish to minimize the cost of stormwater management, because it’s cheaper than laying concrete.
Within the InfoDrainage software, Tavera was able to model the ideal LID to get a real-live view, to see the accurate extent of any body of water needed and how the underdrain connects vegetated channels used in land development designs to divert stormwater runoff.
Raising awareness in Oklahoma for LID
Tavera successfully projected a 100-year storm event in Oklahoma City and Tulsa. With LID implementation from this model, peak flow was reduced from the 100-year storm event in Oklahoma City, earning 30% flow reduction in one of the most troubled areas in the city. Likewise, a thriving district in Tulsa experienced 57%-80% flow reduction, reducing peak flow from the 100-year storm event. So, if Oklahoma City were to get a huge storm like this, the LID drainage design model will be able to handle the flow within the pipes.
Tavera raised awareness in Oklahoma City and Tulsa on how efficient LID drainage design can be. When the model was completed, Tavera delivered compliant, sustainable, and cost-effective designs. Due to her work reducing peak flow reduction and water quality improvements, and her creativity using InfoDrainage to model the LID, Tavera graduated from Engineering student to earning a position as a Water Resources Engineer with a top industry firm, Jacobs Engineering.
Watch the presentation
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