The problem of flooding can easily be controlled through proper landscape planning. Part of the reason our streets and rivers flood every time it rains is that most of our drainage systems are designed to convey rain water out of our compounds, neighbourhoods and cities.
Our conventional landscape is often slanted or mounded in shape, complete with massive impervious surfaces and hard drains. This causes it to spill water rather than absorb it.
A well planned, water-harvesting landscape on the other hand is concave, with plenty of low points to hold rainwater on the site and keep it out of the streets and rivers.
Soft features
Features such as swales, percolation chambers and rain gardens can be included in the landscape to manage storm water. A swale is a shallow ditch with gently sloping sides that runs gradually downhill in the direction you want water to flow. This allows rainwater to soak in as it goes. A percolation chamber can be dug at a low stable point on your compound. Water gets into the chamber and continues to percolate down into the soil, recharging the groundwater.
Rain gardens are planted depressions that allows storm water from impervious surfaces like roofs, driveways, walkways, parking lots and compacted lawn areas, the opportunity to be absorbed into the soil. While these soft storm water management systems may not completely eliminate the need for culverts and engineered drainage systems, they can greatly complement them and improve their efficiency.
Storage systems
Harvesting storm water is a good way to store up water. When setting up a water storage system, your first task is to study your site to determine where the water comes from and where you can intercept it.
The main idea behind a water-harvesting system is to collect water from as many places as possible and deliver it to as many places as possible.
Start at the high points of your land and follow the path of the water as it flows across the ground, running along low points in the terrain. Follow the water as it runs off your roof into gutters and downspouts. It is best to perform this water-flow check while it is raining so that you see what really happens, not what you think might happen.
Imagine the shape of your land in light of your objective: Slowing the moving water and giving it as many opportunities as possible to soak in and irrigate your garden.
The writer is a landscape architect
