River Management Techniques. Upper Wharfedale Best Practice Project (Information Series No 6)

6.0. Creating riverside buffer zones, fencing and stockwater provision

6.1. Provision of stockwatering facility

BACKGROUND INFORMATION

The upper Wharfe is a dynamic river subject to high winter flows and flooding of adjacent fields. River bank erosion is severe in isolated cases but in other instances, minor sources of erosion and silt input to the river exist and are exacerbated by reduced bankside vegetation as a result of unrestricted livestock grazing.

6.1

LOCATION:
Kilnsey, SD 975706

DATE UNDERTAKEN:
Spring 2000

COST: Watering Point £400, fence (600m) £1,750

DESCRIPTION

The section of river bank selected for improvements was used to hold cattle and sheep at various times throughout the year and was grazed down to the edge of the river. Some areas of banking exhibited minor erosion damage and slumping. By agreement with the land owner, about 500m of bank was fenced off to provide a riparian buffer strip to allow recovery and the natural regeneration of a more diverse bankside vegetation. As part of the scheme it was necessary to maintain a provision for stock watering and advantage was taken of the topography to place a purpose-designed watering point within the new fence line.

DESIGN

This was located in a natural dip in the river bank, which allowed low summer flow levels in the adjacent river section to be accessed by livestock with a minimum need for excavation of land. The river bed at the point chosen had a stony substrate and the constructed access to the watering point was similarly stoned to avoid siltation.

A set of galvanised steel gates was prefabricated to close off the gap left in the new fence line and can be hinged out into the river as a semi-permanent fixture to allow access for stock to drink. In high winter flow conditions stock are normally removed from this land, and the design allows for the gates to be moved back parallel to the fence line to reduce the risk of damage from flood-borne debris on these occasions.

Approximately 500m of stockproof fence was installed on the right bank of the river and set back about 5m from the edge of the river to follow the natural curvature of the channel. The brief included the need to install the fence in independent 50m sections, with double straining posts in each section to reduce maintenance costs in the event of flood/debris damage. Stile access for anglers was provided at about 150m intervals.

The fence ends were tied into an existing enclosure line at the site upstream limit. Advantage was taken of steeply rising ground and a sheer faced limestone river bank at the downstream fence limit to install a post/rail fence to close the fence line out of peak river flow conditions.

 

SPECIFICATION

The fence was erected in accordance with BS1722 and the wire complied with BS4102. The netting was C8/80/15 galvanised steel. A plain groundwire was used, together with a single strand of galvanised mild steel and single barbed top wire, to obtain a fence height not less than 1.07m above ground level. Pressure-treated peeled timber was used. Straining posts were a minimum of 2.5m long and 150mm in diameter placed at a spacing not exceeding 75m, and were required at fence ends, corners, turning points and changes in gradients. Struts were a minimum of 1.9m long and 100mm in diameter and were required to be notched into strainer posts at an angle no greater than 45 degrees. Intermediate posts were round in section, of minimum diameter 100mm and were placed at a spacing not exceeding 2.7m.

SUBSEQUENT PERFORMANCE

The river has been outside its banks on several occasions since the work was completed. The fence has not been damaged by the high flows, which had left wrack debris in the field beyond the fence line and on the base of the fence. Minor damage to the stockwater gate had occurred but this could have been avoided if the gate had been secured as designed to be operated in flood conditions.

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