Flood risk reduction, Road Town, Tortola, BVI US$150,000

The ‘Ghetto’ area in Road Town was an area of concern, given the apparent lack of controls in place to prevent flooding of the area. The November 2003 floods affected this area particularly badly. The BVI Department of Disaster Management DDM detailed a set of specific drainage problems in the area. The area lies at the foot of steep slopes with shallow regolith, and thus there is little hillslope infiltration of rainfall that is possible. The immediate backslope topography and geology thus render the area liable to flooding.

There were two principal causes of flooding backflow [reverse flow] from the main channels into the area along three minor channels traversing the area, and unmanaged highway surface water flow.

From the site visit and talking to residents 3 interventions would appear worthy of immediate consideration:

• Raising channel bank levels to the same, consistent elevation throughout the area to prevent backflow and flooding This intervention would thus ‘secure’ the protection of the area to a consistent elevation;.

• Installation of manholes and grid to direct flow of water from the road into the covered channel, thereby preventing flow into the area

• Construction of sediment trap. A location having easy access for clearing. was selected The trap itself would need to be formed by raising the side walls immediately before the covered section, since the invert of the channel is on bedrock at this point.

Figure 1 shows one of the minor channels entering the main channel. Figures 2 shows a resident indicating the height to which the 2003 water levels reached.