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Archive for February, 2010

Restoration – River Lambourne Newbury

Saturday, February 27th, 2010

The River Lambourn had become devoid of many of the natural characteristics found within chalk stream rivers. Throughout the last 100 years the river has become twice the width of what it had been leading to reduced flow conditions. The slower flow allowed silt deposits to smother the natural river bed gravels upon which the fish, invertebrates and vegetation were all dependant upon. The tree canopy to the river banks had become dense over sustained periods and many areas of the river corridor lacked natural light.

River lambourn restoration Land and Water Case Study

Specialist consultants and project engineers worked closely with Land & Water Services to deliver the restoration project. The works covered some 2 km of river which is a designated Site of Special Scientific Interest. Large areas of tree canopy were reduced via the selected felling of the tree limbs in order to reintroduce natural light to the corridor. All felled timber was retained upon site for reuse within the project. New revetments were installed from the bank with retained material from the tree felling being utilised to face and infill the revetments. Large tree limbs were installed at upstream angles to the bed of the river to act as flow restrictors.  These tree limbs along with the revetments narrow the river and deviate the water flows resulting in water accelerating  around the installations (conditions favoured by fish species).

Over 6,000 tons of gravel was placed into the river in order to raise the bed height, again accelerating river flows but equally providing spawning areas for fish & other aquatic species.

Works were undertaken within urban areas proving highly restrictive for access. Land & Water acted as principal contractor under full CDM regulations.

River lambourn restoration long reach excavator in riverRiver lambourn restoration river flow