Tidal Heights in Hyper-Synchronous Estuaries

Ian M Kidd,Shuhong Chai,Andrew Fischer

doi:10.4236/nr.2014.511053

Abstract

Inconsistencies between datasets are examined with reference to flood tidal elevations in the Tamar River estuary, Tasmania Australia. Errors in a 30-year-old commonly cited dataset have been perpetuated in subsequent publications and datasets, and a clarification is herein provided. Elevation of the flood tidal wave as it propagates the estuary is evident in mean tide level and mean sea level, although the analysis is compromised by the temporal differences of the datasets. As sea levels rise due to global warming, the importance of accurate on-going sea level data in any estuary will become more acute.

Highlights

Expression of elevation on the surface of the Earth is not a trivial matter, and many countries develop their own systems
The Launceston data used by Foster et al [8] had a datum of Low Water Ordinary Spring Tide (LWOST) or −2.26 m Australian Height Datum (AHD); 5.238 m below an existing bench mark on the City of Launceston’s Customs House, which is adjacent to the Charles St Bridge (Figure 1(c))
Our results confirm that the figure for tidal heights produced by Foster et al is inconsistent with data from other sources

Summary

Introduction

Expression of elevation on the surface of the Earth is not a trivial matter, and many countries develop their own systems. In Australia, the system used is the Australian Height Datum (AHD) which is an elevation relative to mean sea level (MSL), as measured at one of 30 reference stations around the Australian coast [1]. Tasmania has two such stations: Burnie and Hobart (Figure 1(A)). The geoid to which AHD refers is not a true spheroid but undulates due to variations in the sea surface, caused by ocean currents, the Coriolis force, and meteorological influences. 0 m AHD is the MSL at any one of the 30 reference points around Australia, but may vary depending on which station is used as a reference.

Methods

Results

Discussion

Conclusion