University of Hawaii’s earth scientists have gathered evidence that urban wastewater infrastructure is now being inundated by tidally-driven groundwater. Using computer modeling, the results of their studies show that during sea level rises in coastal areas, groundwater flooding occurs in wastewater infrastructure.
Actually, tidally-driven groundwater flooding is already happening in urban Honolulu. The study revealed higher ocean water levels have been moving toward the coastal oceans and entering storm drains, likely to create a negative impact on the quality of coastal water and subsequently, adversely affect ecological health.
Researchers led by Trista McKenzie, a postdoctoral researcher at the University of Hawaii said that the results of their study have confirmed that tidally-influenced groundwater flooding has been causing wastewater discharge in storm drains. Ms. McKenzie added that while they predicted such results, she and her study co-authors were surprised by the scale and prevalence of the evidence they collected in relation to those processes.
How Groundwater Flooding Will Affect the Environment and Human Life
Along with study co-author,coastal geologist Shellie Habel and study advisor, Henrietta Dulai, an associate professor at the School of Ocean and Earth Science and Technology in the University of Hawaii in Manoa, they discovered that during high level sea rise, the floodings are sending untreated wastewater into storm drains, which are then subsequently discharged in streets and sidewalks.
Such occurrences not only pose as traffic impediments, they also prevent access to emergency vehicles. Contaminated water inundation can also threaten human health.
Moreover, the research team found evidence that in many low-lying coastal areas, human-contributed contaminants that have been discharged by storm drain flooding were in large concentrations; posing high risks for negative consequences that impact coastal and aquatic organisms.
Ms McKenzie warned such threats and negative consequences can be expected to occur in even greater magnitude and frequency in the future.
Mitigation Measures Recommended by the UH Researchers
Ms. McKenzie and her team give advice to coastal municipalities to implement mitigation strategies in minimizing flooding opportunities. Prevention must occur in the channels connecting wastewater infrastructure to drinking water sources and recreational water.
It’s also important to decrease the sources of contaminants by:
- Installing one-way valves for storm drains,
- Monitoring repairing defective sewer lines,
- Decommissioning cesspool, and
- Constructing raised streets and sidewalks.