RIVER EROSION

Southland Times, Issue 22471, 6 November 1934, Page 3

RIVER EROSION

PROTECTION AT EAST GORE. report of engineer. The Gore borough engineer (Mr E G. Wilson) submitted the following report to the council at last night s meeting in reference to erosion occurring at East Gore on the banks of the Mataura river:— The only effective method of stopping erosion of this bank is by rock paving. This is giving highly satisfactory results in many places and is now considered standard for this purpose. It is, however, costly and in the case under review the value of the land being eroded may not justify it. A certain amount of useful work could be done by lining the banks with willow branches and trunks and anchoring them securely. There is, however, another aspect of the case that requires notice. Any system of protection on the east will have a tendency to cause greater erosion lower down on the west bank and this is already becoming serious and may cause more difficulty than the east bank. Everything considered, I think that without going to excessive cost a certain amount of useful work could be done by cutting a narrow channel along the line at which the gravel is now being carted out. If a certain amount of river water can be induced down this channel it will have the tendency to relieve the quantity of water at present causing erosion on the western bank and at the same time cause an increase of velocity down the eastern side of the river which would in turn cause a deflection from the east bank. This new channel would have the tendency to set up a new action by the river in regard to its eroding powers and should eliminate to a certain extent necessity of bank protection. A judicious use of rocks and willows afterwards should in time make the hunks secure. It is difficult to say, but I think that the river on the east bank has about reached the limit of its eroding powers. On the west bank, however, a direct set-in is very noticeable and something should be done to relieve and if possible break this current. The report was referred to the Works Committee.