The hydrodynamics of the southern basin of Tauranga Harbour

Abstract

The circulation of the southern basin of Tauranga Harbour was simulated using a 3-D hydrodynamic model ELCOM. A 9-day field campaign in 1999 provided data on current velocity, temperature and salinity profiles at three stations within the main basin. The tidal wave changed most in amplitude and speed in the constricted entrances to channels, for example the M2 tide attenuated by 10% over 500 m at the main entrance, and only an additional 17% over the 15 km to the top of the southern basin. The modelled temperature was sensitive to wind mixing, particularly in tidal flat regions. Residence times ranged from 3 to 8 days, with higher residence times occurring in sub-estuaries with constricted mouths. The typical annual storm events were predicted to reduce the residence times by 24%Á39% depending on season. Model scenarios of storm discharge events in the Wairoa River varying from 41.69 m 3 /s to 175.9 m 3 /s show that these events can cause salinity gradients across the harbour of up to 4 PSU.

Attenuation of Tides and Surges by Mangroves: Contrasting Case Studies from New Zealand

“…The mesotidal estuary has an average spring tidal range of 1.62 m and neap range of 1.24 m [26]. Due to the complexity of the estuary, exact tidal ranges are location-dependent [27].…”

“…dependent [27]. The shallow lagoon, with an average depth of 3 m at low tide, has extensive intertidal areas that make up nearly 2/3 of the estuary area [28].…”

The links between entrance geometry, hypsometry and hydrodynamics in shallow tidally dominated basins

“…Contrastingly, enclosed estuaries and tidal basins (e.g. Van Maanen et al, 2013;Tay et al, 2013) are often much shallower and are separated from the open ocean by rocky headlands, sand spits or barrier islands. Recent work has highlighted the importance of defining landscape settings when studying estuarine systems and tidal basins (e.g.…”

“…Wang et al, 2002;Bearman et al, 2010;Herrling and Winter, 2014;De Vet et al, 2017) that are based on available bathymetrical data and are calibrated to obtain a match between field observations and simulated variables. Van Maanen et al, 2013;Tay et al, 2013) are often much shallower and are separated from the open ocean by rocky headlands, sand spits or barrier islands. Funnel-shaped basins, such as wellstudied systems in the United Kingdom (e.g.…”

Implications of nutrient enrichment for the conservation and management of seagrass Zostera muelleri meadows

“…Three sites (Figure ) were chosen to reflect the different sediment characteristics that were anticipated to result from different seagrass responses to eutrophication. As the northern and the southern basins are relatively independent hydrodynamically (Tay, Bryan, de Lange, & Pilditch, ), sites were only selected within the northern basin to avoid significant hydrodynamic differences. The selected sites were similar in immersion periods but varied in sediment characteristics and seagrass properties (see the Results).…”