Lhanbryde Flood Alleviation Scheme | Royal HaskoningDHV

The village of Lhanbryde, near Elgin in Moray, suffered from five separate flood events during the 1990s. The most severe was in July 1997, which caused flooding and damage to around twenty residential and five commercial properties in the area. Without flood alleviation measures, studies showed that there was a 50% chance of flooding in any one year, with a 10% chance of severe flooding, similar to that experienced in 1997, being experienced.

The Lhanbryde flood alleviation scheme (FAS) provides a 100 year standard of protection by the provision of an upstream flood storage reservoir, in combination with improvements to the capacity of the watercourse through the village.

Material for the dam, which is 200m long and 6m high, was sourced from an on-site borrow pit. The dam is capable of storing 140,000 cubic metres of water. Discharge following a flood event is via a fixed orifice control structure and takes around 40 hours.

The Lhanbryde FAS is the first of the Moray Flood Alleviation schemes to be completed and has a capital value of £2million. Construction of the scheme was completed in July 2005.

In September 2009 a flood event with an estimated 1 in 300 year return period hit the area. Despite this flood event exceeding the design standard by a factor of three, the scheme performed well and defended Lhanbryde against an estimated £1.5 million of damages.