These are the five main reasons low lying gardens flood.
Heavy sustained rainfall. The simplest explanation is heavy rain. Wherever you live, you are surrounded by drains and public sewers designed to drain the rainwater away
into water treatment plant owned and operated by the water and sewerage companies. In most cases, it does its job. However, sustained heavy rains over a long period
can overwhelm these systems, especially where roadside drains have been neglected and become blocked and the water doesn’t drain away
as quickly as it needs to causing the water in the drainage systems to back up, and the water rise. Unfortunately if your garden is lower than the surrounding properties it's heading your
way! Into your garden!
Rivers overflowing. You may not have had heavy rain in your area. However, if you live near a river where areas upstream have had heavy rainfall, it could lead to flooding
where you live, especially if the river has become blocked down stream by debris or fallen
Nowhere for the water to go. Roads in our cities and towns, car parks our own and neighbours driveways and patios are mostly made of concrete and
other impermeable material. Meaning there is no ground for water to sink into anymore. So, where is the water going to go? It is going to flood low-lying gardens.
Melting Snow and Ice. Melting snow and ice has to go somewhere. A combination of the factors above mean once again, it's heading for you.
High water table. I have explained this in more detail here. Water table information
These are just a few examples of common causes of floods, but sometimes you need to look a little closer to home! Clogged or broken pipes, leaking gutters, down pipes discharging into the ground
instead of being connected into the drainage system, dripping outside taps, impermeable material used to construct our driveways and patios. Mud and
other rubbish brushed over kerbside drains.
Before setting about raising your garden, it might be worth considering a couple of other options. One option described here Building a Bund or Levee really can protect your home from flooding. You can find other solutions in the website menu.
The benefits of raising a garden;
You garden will be above the floodplain and associated flooding problem.
You and your kids won't be walking on a bog.
Plants will grow again.
The problems associated with raising a garden will be;
The underlying cause will still be there and you could be creating one big bog unless you install a drainage
Depending on how high you intend to raise your lawn or garden, you might need to get permission or at the very least
consider the effect on the environment and people around you.
Where will the flood water flow to ?
Raising a lawn or the complete garden surface above the flood-plane will almost certainly have an effect on yours and
others privacy, you could end up 2 feet higher and your neighbours 2 foot lower.
Unless you raise the height of boundary fencing or hedging you will be looking down on them and they will be looking up at
A six foot fence erected on the new level will be eight foot high on the neighbours side, probably needing planning permission.
Other important considerations.
Adding topsoil to permanently saturated soil without first laying a drainage course of clean rubble (explained below) will
create one big bog garden.
If you want to grow deep rooting plants like potatoes, carrots, parsnips etc. you will need a deep bed of
Don't bury manholes.
What is a floodplain.
A floodplain or flood plain is an area of flat or nearly flat land that is adjacent to a stream or river, stretching from the
banks of the river or stream to surrounding higher ground and experiences flooding during periods of heavy rainfall and run off from higher ground.
The run off can be from higher ground further up-stream.
Put simply, a floodplain is an area near a river or a stream which floods when the water level rises.
18 inch high retaining walls will need to be built around the
complete area being raised. These can be built using breeze blocks or any material that won't rot set on a sound footing. Bear in mind you won't see the retaining wall, just the top, as
it will be filled with soil. Strength and durability are more important than looks. For large areas building a bund may be the answer, this page describes how to construct a bund.
Slope the surface of the frame very slightly toward where you
intend the water to drain away. This should not be your neighbours garden or the footings of your house.
Weep holes for drainage need to be formed every 2 meters
and every 1 meter at the lowest end of the slope.
Top tip If you have got good access to the area you are raising leave a gap in the wall wide enough to get a digger and tipper lorry through. It's a lot
easier if you tip the rubble and then the soil directly onto the area being raised. Then finish the wall.
There are Pros and Cons involved in owning a home built on a floodplain. Pros; such as boating on the Thames,
fishing, bird watching, the land is rich and fertile, relaxing sound of running water.
You will probably pay significantly less for the property than for a similar house on the hill, possibly out weighing a major Con, higher insurance premiums. Other cons are: Sewers filling with river or groundwater and backing up into the house, Having to move and refit all electrical points and switches, if you are a worrier lying awake all
night every time it rains. There are a lot of pros and a lot of cons. Thoroughly check
it out before you buy.