Tidal circulation in Tasman and Golden Bays: Implications for river plume behaviour

Abstract

An investigation into the tidal residual circulation in the Tasman/Golden Bays system was performed. This investigation involved collecting hydrographic and current meter data, and configuring a numerical circulation model. The model was able to reproduce the gross features of the major tidal flows within the system revealed by the data. The simulated tidal residual circulation conformed to that previously suggested, except along the western side of Tasman Bay where this investigation suggests that residual flows move northwards. The validated model was then used to produce simulations of the fate of the plumes from the major rivers. Salinity field simulations describing different river flow and wind direction/velocity scenarios suggest that the Motueka River plume can cover considerable proportions of western side Tasman Bay, extending into Golden Bay during flood conditions. The embedded sediment transport model was also used to investigate the fate of fine sediments entering the bays. Simulated distribution patterns of fine sediments entering the bays from the four major tributaries were found to be consistent with existing bathymetric and seabed substrate characteristics.

A study of tides and currents in Cook Strait, New Zealand

“…These components have properties in common with progressive and standing waves, respectively. Studies of the hydrodynamics of sub-domains of the GCS region have also been undertaken by Proctor and Hadfield (1998) for Pelorus Sound (a 3-D baroclinic model on a regular grid) and recently by Tuckey et al (2006), who applied a 2-D model to Tasman and Golden Bays.…”

5 Key Challenges and Solutions for Governing Complex Adaptive (Food) Systems

“…Most land use around Tasman Bay is associated with dairy, beef, and sheep ranching, as well as forestry [34,132]. Runoff carrying sediment is directed through prominent currents towards Tasman Bay [140]. New Zealand is unique as an industrial country in that most of its export economy is driven by agriculture and its agricultural sector is fully exposed to international markets (New Zealand has no protection oriented subsidies, [141]).…”

“…First, sediment is added to the bay mainly through input from terrestrial ecosystems, illustrating the importance of cross-system impacts [140]. Most land use around Tasman Bay is associated with dairy, beef, and sheep ranching, as well as forestry [34,132].…”

Motueka River plume facilitates transport of ruminant faecal contaminants into shellfish growing waters, Tasman Bay, New Zealand

“…During dry conditions when river flows and concentrations of faecal bacteria are low, it is unlikely that shellfish in the AMAs are at risk of contamination from land-based contamination sources. This is largely because the AMAs lie within a well flushed embayment (Tuckey et al 2006) and are located at least 6 km away from river inputs. In addition, dry periods would be accompanied by high levels of solar radiation, which is the primary factor regulating mortality of faecal microbes (Gameson & Gould 1975;Wilkinson et al 2011).…”

“…Tasman Bay is a shallow and highly productive water body; aquaculture for Greenshell TM mussels is currently being developed in three aquaculture management areas (AMAs) that collectively represent an area of 15 km 2 . Following heavy rainfall, the river produces extensive low-salinity plumes that can extend more than 18 km offshore and encompass the area of the AMAs (Tuckey et al 2006). During the flood event, we conducted a hydrographic survey of the Motueka River and the river plume in order to investigate the source and fate of faecal contaminants in Tasman Bay.…”