Fisheries Improvement Project 2016-17

Elmswell & Driffield Trout Stream

The aim of this project is to firstly re-instate a section of the Elmswell Beck at TA 02077 56601 where a tree has caused sediment build up and diverted the flow creating scour leading to loss of a large amount of soil and vegetation into the river channel. The second phase on the Driffield Trout stream is to create a meandering channel by using course woody material & logs gained from the removal and or crown reduction of nearby overhanging trees.

Elmswell Beck at TA02077 56601 showing massive erosion to the right bank.

Original river bank line – stakes being ‘spiled’ (woven) with alder, willow & poplar gained from operation to ‘skylight’ overgrown sections of Driffield Trout stream.

Backfilled the new bank reinstatement with silt from the river channel. Coir sheeting protecting any soil loss. Hire of a long reach machine made it possible to complete this section from a single bank.

 

Driffield Trout Stream

Material gained from crown reducing overhanging trees being used as a ‘kicker’ to divert flow towards the centre channel.

Moving brash to create a clearing within the former shaded area on the river bank.

Aerial view of stream narrowing formed by infilling logs pinned to the river bed.

Machine working in the river channel. Raking the compacted bed and placing arisings into the LWD installations. The machine is following a marked channel indicated by the yellow pole. This method was used over the full length of the project site, 450 metres.

River bed was made up of compacted gravel and sediment.This was raked to a depth of between 30 – 50 cm. Any sediment caused throughout this operation could be captured by the use of ‘Sedimats’ placed at strategic points downstream. The raked channel was kept to a width of between 2.5 – 3 metres. It was meandered through the existing over wide channel.It can be seen that this kind of project can only be undertaken during a very low flow period.

Top picture (viewing upstream) shows overhanging willow. Bottom view, (downstream) the tree is part cut through near the base and allowed to rest on the riverbed. This hinging keeps the tree alive and with the crown branches trimmed does not create a snag to collect floating debris.

 

A. Mullinger

January 2017