Poorly managed rain-water can lead to flooding and damage your property

You may have bought land or are already residing in a place that is prone to flooding. Every time it rains, your compound is flooded and sometimes the water gets into the house.

This is a problem for people who reside in Bwaise, Kalerwe, parts of Namboole and Nateete Kigaga zone, among many. Whenever it rains, the rainwater has to be drained away.

Some people drain water into underground tanks where it is stored and later withdrawn for use. Others let it follow its own course. David Kireli, a civil engineer at the Ministry of Education says stopping rain water from draining under your house or in the compound is a fairly simple process.

 “Doing this may even lower your water bill by allowing you to use harvested rain water. It can irrigate the flowers, vegetables, lawn and others,” he says. Rainwater falling on natural open ground will just lie on the surface, if the soil is impermeable, evaporate into the air, run off into streams and rivers or seep into the ground. According to Kireli if rain water flowed off the roof of a building in an uncontrolled way, it could easily flood the area around that building.

Floods in your home

According to Ronald Lotet, a senior environment officer in Mubende, some lowland areas may receive less rainfall, hence minimal flooding. He says where the water is coming from also matters. There are areas that receive heavy rainfall, making all the land in their catchment area susceptible to floods.

 “The catchment area where the house is built matters, the further downstream the bigger the catchment area hence the more vulnerability of flooding.”  This makes areas like Bugolobi, which are near Lake Victoria more vulnerable as they are the catchment area of much of Kampala.  He also mentions the nature of the soil structure as a factor on how long water will hold in a particular area. From those that allow easy movement of water to those that hold it.

On protection against the water, he says a buffer zone like reinforced walls can protect the house from flooding although he advises builders to use precast reinforced concrete if the house is to be sustained.

Fred Lukoda, a civil engineer says the first step in protecting a house against flooding is to establish whether the flooding in the area is seasonal or temporary. He advises the partitioning of the plot into two parts to prevent flooding on flat land. Part A for the house and part B for the pond where the water is to drain.

If the plot has access to the drainage, he advises the developer to drain in the drainage system. “The channel should be above two metres above the surface,” he points out. Lukoda says eucalyptus or pine trees should be planted to hold the soil and reduce the amount of water in the soil.

He further says having ground beams prevents the house from sinking. He warns against mixing waste and water together. “The waste must not get contaminated with the water. It must be treated separately.”

Ways of controlling water

Rainwater from the roof may also be blown into the house through the windows. If the rainwater is not properly drained away, it affects the part of the construction on which it is falling. The use of a soak away pit would be of help in this situation.

• The drainage channels or pipes should direct the water into this pit.
• The soak away pit is a round circular pit dug into the ground.
• It is filled with stones to prevent the sides from collapsing.
• The water within the compound drains into this pit and then soaks into the ground.
• The pit should be about three or four metres from any building.
• The size of the soak away pit will depend on the area to be drained and the average annual rainfall.

Kireli says it is important to know the type of soil into which the water is to be drained. Clay soils should not be used for the soak away pit because the water will not easily soak into the ground. This will cause the pit to fill up quickly and the water will flow back and flood the compound.

How you can avoid flooding in your compound

• Ensure that the soil graded slopes away from the house. Soil that slopes toward the house traps water by the foundation, and flat ground doesn't channel water away.
• Install a rainwater catchment system. This not only keeps rainwater from harming your foundation and saturating the area around your home,­ but also gives you free water to use around the house.

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