New Zealand Journal of Marine and Freshwater Research abstracts

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A temperate, tidal lake-wetland complex 

1. Water balance and ecological implication

Marc Schallenberg
Carolyn W. Burns

Department of Zoology
University of Otago
P.O. Box 56
Dunedin, New Zealand
email: marc.schallenberg@stonebow.otago.ac.nz

Barrie M. Peake

Department of Chemistry
University of Otago
P.O. Box 56
Dunedin, New Zealand

Abstract   A water-balance model was developed for a tidal lake-wetland complex to: (1) determine the relative contribution of hydrological flows through the lake-wetland complex; (2) determine the tidal and non-tidal hydraulic residence times of two lakes in the lake-wetland complex; and (3) estimate the potential importance of groundwater inputs to the lake-wetland complex. All surface hydrological inputs to the system were either measured or estimated over 1 year. Daily evaporation from the water bodies was also estimated. Discharge at the outflow of the lake-wetland complex was monitored to calculate the net daily outflow. A correction procedure was used to remove the error resulting from aliasing of the daily calculation period and the tidal period. The difference between the measured net outflow and that calculated by the water-balance model indicated that a large amount of net discharge from the lake-wetland complex may have been a result of previously unrecognised groundwater inputs to the system. The non-tidal hydraulic residence times of the two lakes differed markedly as did the relative importance of tidal inflows. The influence of variation in tidal and non-tidal hydraulic residence time on limnological processes is discussed, particularly with respect to impacts of global climate change on tidal lake ecosystems.

Keywords   hydrology; groundwater; water balance; lake; tidal; estuary; Lake Waipori; Lake Waihola; lagoon

M02015 Received 4 March 2002; accepted 4 September 2002; Published 20 June 2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37: 415-428
0028-8330/03/3702-0415 $7.00 © The Royal Society of New Zealand 2003

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