A Guide to Surface Water Drainage and Flooding

Surface water, also known as rainwater, storm-water or run off, is channelled through roof gutters, downspouts and road gullies into surface water drainage. This usually runs into the nearest watercourse.

Surface water (from rain or melted snow and ice) will also seep into soft land such as grass and soil. But increasing urbanisation (covering land with impervious materials, such as concrete, tarmac, etc) has reduced the surface area available to absorb rainfall. In extreme weather, land becomes saturated and, when heavy rainfall follows heavy rainfall, the water table stays high and excess has nowhere to go. The result, as we are seeing more and more often, is flooding.

Time and again we see flash floods devastating communities; residents being rescued from rising waters, possessions ruined, cars washed away, roads collapsing, homes and businesses made uninhabitable and, on occasion, lives lost. A grim reminder that we are at the mercy of the elements.