by Curlan Campbell
- More impervious surfaces channelling water directly into drains and rivers, cause substantial increase in downstream flow to St John River
- Blockages at humpback bridge forces water out towards sides and into stadium
- Due to significant amount of rainfall experienced, additional work may be necessary upstream in project’s second phase
The St John River is experiencing heightened flooding, exacerbated by climate change-induced rainfall and the misdirected water from residential drainage systems.
Kevin Blache, the Chief Technical Officer at the Ministry of Infrastructure, Public Utilities, Civil Aviation, and Transportation, highlighted this as a contributing factor while addressing questions regarding the recent and recurring flooding in the River Road area. During a press conference on Tuesday, he highlighted that these issues persist despite the mitigation efforts implemented through the St John River Flood Mitigation Project.
“One of the contributing factors to the situation we’ve observed is related to what happens further upstream in the river’s catchment area. Due to the increasing number of impervious surfaces being constructed — such as paved driveways — many homeowners are redirecting their downspouts into roadside drains and directly into the rivers. This practice significantly increases the volume of water that flows downstream into St John River,” Blache explained.
Blache mentioned that revisions have been made to the proposed design for the St John River Flood Mitigation Project. However, due to the significant rainfall experienced, additional work may be necessary upstream in the second phase of the project, which will consider the excess surface runoff from residential homes.
He provided insight into the ongoing work needed in the River Road area. “The intended plan, particularly near the stadium, is to construct a new humpback bridge. The current design of the existing humpback bridge is problematic because it is lower and located close to the edge of the road. This positioning causes it to become blocked with bamboo, logs, and other debris, creating a hydraulic jump in the river that forces water out towards the sides and into the stadium. Therefore, until we seal all the openings in the river that allow water to exit, we are likely to face similar issues.”
The plan going forward is to start construction of the new humpback and another bridge located by Steele’s Auto Supplies in the upcoming dry season, which in theory, should help prevent sections of the riverbank from eroding and flooding the road during heavy rainfall.
Prime Minister Dickon Mitchell, who attended yesterday’s press conference, stated that the government would need to consult a flood mitigation expert. He is not convinced that the remaining remedial work will effectively address the flooding issue. “I’ll be honest with you, in light of what I’ve seen, I don’t know that merely having two new bridges and repaving roads is going to address the flooding that we are facing at River Road, and I don’t know that building a 200-foot wall, or 10-foot well, will address it. So it’s clear from where I sit that I think we are going to have to get a flood mitigation expert to review all of this and to provide further guidance.”
Meanwhile, Terrence Smith, Acting General Manager of the National Water and Sewerage Authority (Nawasa), has announced that preliminary estimates indicate the damage to water dams has exceeded $800,000. This damage is a result of 4 distinct periods of extreme rainfall that severely impacted the dams, intakes, raw water lines, distribution lines, and water treatment plants. As damage assessments continue, he noted that this figure represents a 60% increase compared to the losses incurred following Hurricane Beryl.
He indicated that 14 out of 28 surface water systems were adversely impacted during the first extreme rainfall event. “The impact on our ability to provide drinking water is significant, approximately 60% worse than the damage we experienced during Hurricane Beryl,” Smith said. “We are still conducting damage assessments, but our preliminary projections indicate a much larger impact this time. While Hurricane Beryl affected 7 or 8 of our dams, this event has impacted 14 out of 28 dams. We estimate the cost of the damage to be over $800,000, based on our initial assessment.”
Over 10 days, over 50 landslides occurred due to heavy rainfall. Cleanup efforts are ongoing, especially in severely affected areas, where authorities are forced to remove mud and debris up to 10 meters high from roadways.
