Lower Mole flood alleviation scheme
The Lower Mole flood alleviation scheme – covering Garsons Farm to Hampton Court – has reached the end of its design life. It is based on a series of six sluice gates which are showing signs of degradation. The Environment Agency has set up a website to outline the problem, along with options for the future of the scheme, and has invited comment from interested parties.
There are six options, the first two being doing nothing or very little, which simply puts off finding a proper solution. Option 3 involves new sluice gates. Options 4, 5 and 6, each involve alternatives to gates. The flow control effectiveness of these alternatives, in the Lower Mole context, is not clearly demonstrated/evaluated and they each have the potential to reduce or dry out water levels at certain times. This would affect local amenity: boating and other river activities could become impossible. Also, lower water levels and dry beds would increase concentrations of the polluting materials which find their way into the river.
Sluice gates have been very successful in controlling flows over many years and, given the importance of this for the many local residents affected, ERA has submitted a preference for option 3: installing new gates. The detailed pros and cons of each option are on the EA website, www.lowermolefloodalleviationscheme.co.uk including a benefits-to- costs ratio of each.