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Coastal sands of Northeastern Tasmania: geomorphology and groundwater hydrology

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Bowden, Adrian Russell (1981) Coastal sands of Northeastern Tasmania: geomorphology and groundwater hydrology. PhD thesis, University of Tasmania.

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Abstract

A regional study of the Quaternary geomorphology of
coastal northeastern Tasmania defined landforms and deposits
which offer good groundwater development potential, and also
pointed to geomorphic problems worthy of more detailed research.
Marine transgression and regression appear to have been a main
feature of landform development in coastal northeastern
Tasmania since Late Tertiary times. The present landscape is
dominated by low, sandy plains created during the Last
Interglacial marine transgression and by aeolian landforms
which were formed during the succeeding glacial stage. The
immediate coastal areas are backed by marine and aeolian
landforms deposited during and since the marine transgression.
The regional study revealed that deposits of possible
marine origin and interglacial age, occur to an elevation of
approximately 32 m. This is — 10 m above the upper limits of
similar deposits elsewhere in Tasmania and is — 26 in higher than
equivalent features in stable areas of mainland Australia. These
relationships indicated that tectonic uplift in Tasmania may
have occurred during the late Quaternary. Further research
indicated that the sea level in northeastern Tasmania most likely
attained an elevation of — 32 in during the Last Interglacial
Stage, and that the area has experienced a moderate uplift rate
of approximately 0.2 m/ka. The stratigraphic relationships
between Quaternary marine deposits also indicate that older,
probably of Oxygen Isotope Stages 7 and 9 age, marine deposits
occur to 49 and 71 in respectively, thus indicating that uplift
in Tasmania has been occurring over at least 300,000 years.
Mapping and examination of the extensive longitudinal
dunes and lunettes during initial stages of the programme
indicated that they are products of environmental conditions
substantially different from those of today. Dune morphology
and grainsize characteristics suggest that zonal westerly air
flows appear to have been stronger and from a slightly more
northerly direction during the Last Glacial Stage than air
flows which occur today. Stratigraphic studies infer that
the temperature was markedly lower during formation of the
longitudinal dunes. Evidence from fossil groundwater podzols
indicates that precipitation during the Last Glacial Stage may
have been only approximately one half of the present rainfall.
Lunette stratigraphy and morphology reveal shifts in the
relative importance of key components to the hydrologic cycle,
such as precipitation, evapotranspiration and surface run-off,
both during and since the late Last Glacial Stage.
The coastal plains of interglacial marine sand form
extensive unconfined aquifers and contain Abundant and
accessible groundwater supplies. Computer and graphical
simulations are applied to pumping test and drilling results,
water table maps and continuous water level records to assess
the groundwater system. Groundwater dynamics are controlled
principally by precipitation and evapotranspiration. The
system is renewable and moderate rates of groundwater withdrawal
may even be beneficial.

Item Type: Thesis (PhD)
Keywords: Sandy soils, Geomorphology, Groundwater
Copyright Holders: The Author
Copyright Information:

Copyright 1981 the Author. The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s)

Additional Information:

Thesis (Ph.D)--University of Tasmania, 1981. Bibliography: p. 306-319

Date Deposited: 25 Nov 2014 00:40
Last Modified: 11 Mar 2016 05:56
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