Hydraulic Efficiency of Penn State Stormwater Bioswale during Rain Events

Open Access
- Author:
- Lennon, Daniel
- Area of Honors:
- Civil Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Lauren Mc Phillips, Thesis Supervisor
S. Ilgin Guler, Thesis Honors Advisor - Keywords:
- Bioswale
Green Stormwater Infrastructure
Water Resources
Runoff Mitigation
GSI - Abstract:
- Background. Stormwater contamination and flooding are common concerns in many populated areas across the globe. Green Stormwater Infrastructure has been introduced to leverage ecological processes to reduce the impact of runoff on urban systems. The following study was conducted to calculate an average percent reduction from stormwater inflow versus outflow at a 16-year-old stormwater infiltration swale on the Penn State campus. Additionally, the data investigated the lag time from rainfall to underground flow in the runoff system. Methods. Precipitation data was gathered in the State College, PA, area for each rainfall event. This data was used to model inflow volume using. A pressure sensor in the underdrain outflow pipe was used to calculate water depth in the drainage pipes, which allowed for an outflowing pipe-flow volume to be found. This data was compared in time and quantity to determine any reduction in volume as well as lag time between the events. Results. The average percent reduction in flow volume, found using data from 4 different events, was 97.77 percent. The loss of water volume is assumed to be from evaporation and infiltration into underlying soil. Also, the sensor data showed an average lag flow time of 4 hours and 30 minutes after precipitation began. This time is accounted for through surface flow across the basin and ground seepage and transport. Conclusions. It is shown that infiltration-based stormwater basins could be effective at reducing the flow volume running off impervious surfaces, even many years past initial installation. They also can significantly delay the flow, to prevent overwhelming sewer systems and downstream flooding.