The episodic and seasonal dynamics of salt transport in the Waitematā Estuary, a well-mixed estuary in New Zealand
- Author
- Chen, Z.; Bowen, M.M.
- Year
- 2024
- Journal / Source
- SSRN preprint article
- Month
- May
- Keywords
- preprint, not peer reviewed; Salt transport, well-mixed estuary, Total Exchange Flow, Waitematā Estuary, spring-neap tides, freshwater discharge
- Summary
- his study investigates the response of salt transport to freshwater discharge events, the seasonal cycle, and tides in the Waitematā Estuary. The salt transport is assessed by both observations and numerical simulations using a gridded salt balance and isohaline salt transport. The Waitematā Estuary represents a unique type of estuary in parameter space: it varies between well-mixed and strain-induced periodic stratification during the spring-neap tidal cycle. Tides create most of variation in salt flux. Spring tides often lead to a net inflow of salt. Higher freshwater discharge (>10 m3s-1) results in net downstream salt transport regardless of the amplitude of the tides. The estimates of estuarine parameters show that the whole estuary becomes partially-mixed when the freshwater discharge increases by another order of magnitude. If rainfall becomes lower on average with more intense events, as anticipated in regional climate projections, the estuary will experience less frequent but stronger salt outflow.