ODPEM Government of Jamaica
Office of Disaster Preparedness and Emergency Management
Search:  Go
Disasters Do Happen
 
Flood Control Structures in Jamaica

Thousands of Jamaican homes and communities are either located near rivers or on lands prone to flooding. The best way to ensure safety from floods is to divert human settlements and economic developments away from flood-risk areas.

However, existing settlements can be protected to some extent by the flood-proofing of buildings and engineering flood control protection works.


The types of flood control structures erected for the various catchment areas of a river vary in purpose and cost.

In the upper parts of the catchment, engineering ing works such as check dams, protect gullies from being eroded by rainfall and runoff impact.

The lower parts of the catchment area are protected by river training works such as retaining walls and bunding.

The various types of flood control structures used in Jamaica are:

 


Check Dams

These are small gravity dams, usually constructed with rocks and mortar or concrete, of variable height and width. These structures are located in small or medium-sized gullies to stabilize riverbed slopes and prevent soil erosion.

Back to top


Retaining Walls

These are rock/concrete block structures built on steep slopes anywhere in the watershed, where the erosion of the base foundation threatens lands and/or homes.

Back to top


Bunding

Bunding is the general name used in Jamaica for flexible structures of variable thickness and length, composed of galvanized wire mesh, stone, wild-cane and riverbed materials.

Bunding is used to prevent bank erosion and landslips and to protect agricultural lands from being flooded.

Back to top


Sausage Groynes

These are long, cylindrical, slightly flexible structures of variable thickness, composed of wire and rocks. Groynes are placed at the foot of banks along small, slow-moving streams, where there are signs of undermining and threats to permanent structures.

Sausage groynes are designed to stop such action by allowing the bank to collapse to an angle of repose in such a manner as to form a moderate slope, which encourages the growth of vegetation.

Back to top


Gabion/Mattress Groynes

These are long, flexible structures of variable thickness, composed of wire and rocks. They are placed on the shaped banks of large, fast-moving streams where severe erosion is occurring and many pose a danger to permanent structures.

Mattress groynes are designed to prevent the further erosion of the riverbank. They trap soil particles to allow a build-up of soil; thereby encouraging the growth of vegetation.

The most commonly used mattress groyne has 1:2 and 1:15 side slopes and a 10' flat top surface covered with a wild cane matting threaded between 12" wire mesh anchoring both teardrops. Both teardrops and mattress are made of stones encased in wire mesh and the mattress is tucked at 1'6" intervals.

Back to top


Paved Drains

These are U-Shaped concrete structures designed to quickly remove water from highly susceptible erodable areas such as road-sides, under-bridges and steep slopes.

  1. Levees:
These serve the purposed of confining flood waters to the stream and to portions of the flood plain. In Jamaica, levees made of clay or earth fill material are being used with some structural modifications and have proven quite effective. The slopes of an earth fill levee should be no more than 2:1. The base should be wide to allow for a gradual slope. Trees and bushes should not be planted on or near a levee because their root systems tend to weaken it.
  1. Flood Walls of reinforced concrete:
Flood walls require very little space and are often used to protect cities and developed areas. They are costly to construct, but involve minimal maintenance costs.
  1. Channel Alterations:
Reduce floods by deepening and widening the channel by cutting meanders. Sometimes these works can have undesirable effects, by aiding the sediment transport process. Care must be taken when channel alternatives are considered.
  1. Detention Ponds:
Ponds placed on and off-side, can minimize the damage to downstream structures by reducing peak flows. They should be considered in the design of downstream protective structures.
  1. Dams:
These structures can be used in Jamaica to control flood peaks, provided suitable impounding sites can be found. Dams are designed for return periods usually exceeding 25 years. Their cost, however, is usually high and their design and construction require careful planning.

 

 

Return to Floods

 

 

Important Notices | Help | © 2008, Government of Jamaica.All Rights Reserved