Erosion and sediment yield from a landing failure after a moderate rainstorm

Authors: A.J. Pearce, P.D. Hodgkiss
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1987, Issue N.Z.J.For. 32(3) 1987, pp 19-22, Nov 1987
Publisher: New Zealand Institute of Forestry

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Abstract: A rainstorm of a size likely to occur once every 1.5-2.0 years caused substantial erosion of a recently formed log landing. Sediment yield from the catchment affected was 3000 times larger than from an adjacent catchment during the storm. Sediment yields from subsequent storms were higher than from the adjacent catchment by factors of 30-80, 2-7 and 15, respectively, for the 1st, 2nd and 3rd years after the storm which caused the erosion. Avoiding hazardous sites for landings, or modifying construction and harvesting techniques to reduce the impacts of fill failures if hazardous sites cannot be avoided, are identified as essential ingredients of good harvest planning. Steep slopes leading directly into streams are particularly hazardous because fill failures are likely to create debris slides or flows which will transport large volumes of sediment into streams. Fill compaction and drainage of landings and roads leading onto landings are essential components of good landing construction.

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