Sea Level Rise Effect on Groundwater Rise and Stormwater Retention Pond Reliability
Singhofen and Associates Incorporated, 11723 Orpington St., Orlando, FL 32817, USA
Department of Biosystems and Agricultural Engineering, Oklahoma State University, 111 Agricultural Hall, Stillwater, OK 74078, USA
Centre for Environmental Policy, Imperial College London, London SW7 2AZ, UK
Department of Physical Geography, Stockholm University, SE-106 91 Stockholm, Sweden
Author to whom correspondence should be addressed.
Water 2020, 12(4), 1129; https://doi.org/10.3390/w12041129
Received: 9 March 2020 / Revised: 6 April 2020 / Accepted: 12 April 2020 / Published: 15 April 2020
(This article belongs to the Special Issue Integrated Water Resource System Modeling to Support Sustainable Water Management)
The coastal areas of Florida, United States, are exposed to increasing risk of flooding due to sea level rise as well as severe hurricanes. Florida regulations suggest constructing stormwater retention ponds as an option to retain excess runoff generated by the increased impervious area and to protect the environment by reducing pollutants from new developments. Groundwater level rise can significantly lower the soil storage capacity and infiltration at retention ponds, in turn, reducing the pond’s capacity to capture consecutive storms due to longer pond volume recovery time. Partial groundwater inundation can affect retention ponds’ ability to decrease peak flow rates and keep the post-development outflow lower than or equal to pre-development conditions. In this paper, the reliability and performance of a retention pond near Tampa Bay, Florida, was evaluated under sea level rise conditions. An integrated surface water and groundwater model was developed, and the groundwater table was projected for future conditions as a function of sea level rise. The results showed that sea level rise could increase the seasonal high water elevation of the retention pond up to 40 cm by mid-21st century. This increase lowered the reliability of the retention pond by about 45%. The pond failed to recover the designed treatment volume within required 72 h because of the high groundwater table, increasing the risk of pollutant discharge. Furthermore, the peak flow and volume of runoff significantly increased under sea level rise and associated groundwater table rise conditions. The study results suggest that it is imperative to consider future sea level rise conditions in stormwater design in low-lying coastal areas of Florida and around the world to prevent poor pond performance and increased risk of flooding in the future.