Quantifying Coastal Sediments using MERIS Data; a 10-year Study in the Taranaki Bight, New Zealand.
Tuohy, Mike; Proctor, Jon; Collins, Stephen
Massey University, NEW ZEALAND
The Taranaki Bight (off the southwest coast of New Zealand's North Island) has six major rivers emptying often sediment-laden water into it. The MERIS sensor on ENVISAT provided both imagery and derived products that could be interpreted to estimate the sediment concentration of these coastal waters and provide an insight into the erosion occurring in the river catchments.
The full archive of reduced resolution MERIS imagery for the Taranaki Bight was evaluated initially to determine which images were useful for this analysis. As an example, in 2011 a total of 200 images were available but only 86 (24% of the days throughout the year) were clear of cloud and able to provide useful measurements. A further 71 images (20% of days) provided useful, cloud-free data for portions of the region. Whenever it was available, the full-resolution imagery was then downloaded. The sediment loads were analyzed in conjunction with rain radar data of the river catchments and river flow and sediment data from permanent sampling sites in the lower reaches of the rivers. The satellite data captured the effect of recent storms and associated erosion; the extent of the sedimentation was clearly seen in the imagery and estimates of the total sediment load were made with confidence.