Trailbikes ruin dunes

Press, 3 September 1977, Page 2

Trailbikes ruin dunes

PA Hamilton Heavy-handed land use by man — including trail bike riding — has been named as one of the main causes of erosion on Bay of Plenty beaches. A Waikato University survey of Bay of Plenty beaches has found that three beaches are either doomed, bad, or hold a potential for disaster. The survey, released yesterday, said that intense coastal subdivision and sand extraction were key factors in erosion of the beaches. Natural factors combining with this included cyclical erosion and natural accumu-

lation or accretion, and ero-sion-accretion on a general and seasonal scale, depending on meteorological factors. Intense human trampling and trail bike riding on access ways and dunes had resulted in instability by damaging protective dune vegetation, said the report. While human misuse of beaches was not the only factor in their destruction “it is reasonable to conclude that intense population does contribute to frontal dune instability.” The report noted that "Ohiwa was doomed, Waihi looked bad, but Pukehina

showed the biggest potential disaster" through coastal subdivision. Long-term erosion generally occurred downdrift from barriers or partial barriers to the shoreline conveyor belt. Shoreline, or littoral, drift was the main way sediment was supplied to the beaches in the Bay of Plenty. Extraction of sand from this littoral system had a deleterious effect on the near-shore beach-dune system. The report recommended that sand extraction from beaches should be carefully monitored.