Description:
<p>Historically, wave data coverage of New Zealand's coast has been poor, particularly for directional records. With very few data sets available of more than one year's duration, it has been difficult to establish accurate wave climatologies. To help fill in the gaps in our wave records, the WAM wave generation model has been established over a domain covering the Southwest Pacific and Southern Oceans. The model has been used to hindcast the generation and propagation of deep-water waves incident on the New Zealand coast over a 15-year period (1979-93), using winds from the European Centre for Medium Range Weather Forecasting (ECMWF). The resulting artificial climatology is expected to provide a valuable tool for researchers and coastal planners. The hindcasts were compared with data from several wave records, and found to provide a satisfactory simulation of wave conditions at sites on exposed coasts (e.g. Hokitika, South Island, West Coast). For regions of more complex coastal topography however, wave spectra can be considerably modified by the processes of refraction and shoaling over seabed of varying depth, diffraction, reflection and sheltering by land. The resulting, highly site-specific, wave transformations were investigated using nested shallow water models, and validated using data from inshore sites at Mangawhai (North Island, north-east coast) and Pegasus Bay (South Island, east coast). Methods were also investigated to filter hindcast spectra for the effects of limited fetch. As a result, good agreement was obtained when the 15-year hindcast was compared with buoy data from Foveaux Strait (at the southern end of the South Island) and Katikati (North Island, east coast), with regression between measured and hindcast significant heights achieving correlation coefficients exceeding 0.8.</p>