Week 4a- Water

In summary, the effects of the proposed abstraction on the river as it flows past the site will be:

• A water level change of approximately 15 mm (low tide) and 22 mm (high tide) (compared with a typical water depth for these scenarios of approximately 6 m and a daily tidal variation of approximately 0.5 m).
• A change in mean velocity of 0.004 m/s (low tide) and 0.002 m/s (high tide) (compared with a mean velocity in these conditions of ~ 0.5 m/s).  Low summertime flows need to be calculated as during this time, the flow and energy will be reduced which changes sediment motion, can increase temperatures, change oxygen concentration and increase the intrusion of a saltwater wedge from the estuary.
• Compared to the existing conditions on the river, and the effects due to everyday tidal variation, the effects on the hydrology and hydraulic regime of the river due to the proposed abstraction will be no more than minor.

Image from teara.govt.nz