On the North Island, New Zealand east coast from Castle Point to Cape Kidnappers, prevailing winds are offshore. However, large climbing dune systems dominate the Holocene dune types and occur in the lee of high bedrock hills. Foredunes are relatively rare and occur across the fronts of valley entrances and where the near-coastal hills are situated further landwards. On this coast, fetch lengths (beach widths) and potential sediment supply are inversely related to dune type and size. Small foredunes occur in the lee of the widest fetches and greatest potential sediment supply areas because the regional prevailing and local near-surface winds both blow offshore. Climbing dunes occur in the lee of the shortest fetches and lowest potential sediment supply areas because local wind flow separation and reversal is common in the lee of the high coastal hills during prevailing offshore wind events.Thus, the widespread occurrences of climbing dunes along this coast are directly related to the operation of large scale flow separation cells that locally reverse the prevailing offshore wind and cause onshore movement of sediment even though the fetch is quite limited.
|Number of pages||12|
|Journal||Zeitschrift fur Geomorphologie, Supplementband|
|Publication status||Published - 1 Dec 2005|