Using coupled models to place constraints on fluvial input into Lake Ohau, New Zealand Phaedra Upton1, Rachel Skudder2 and the Mackenzie Basin Lakes Team3
[email protected], 1GNS Science, 2Victoria University of Wellington, 3GNS Science + Otago University + Victoria University of Wellington 2004: no large storms 0 2000 kg/sec 1/1/10 daily rainfall Godley River modelled suspended sediment load Tasman River LakeTekapo 1/1/00 0 200 mm Lake Pukaki 1995: large summer storm 0 2000 kg/sec Hopkins River Box core #1 1/1/90 daily rainfall modelled suspended Lake Ohau Box core #2 Raymond Film Services sediment load Ahuriri River Figure 2: Lake Tekapo following a large rainfall event in its catchment. A sediment laden inflow plunges into the lake and leaves the surface waters clear. We use HydroTrend (Kettner and Syvitski 2008, Computers and 6 m core Daily Rainfall (mm) 0 200 mm Geoscience, 34) to calculate the overall sediment influx into the lake and 1/1/80 couple it to a conceptual model of how this sediment might be distributed 1969: large winter storm through the lake basin depending on the season to produce model cores. 0 2000 kg/sec 0 3 6 12 18 24km Figure 1: Located east of the main divide in the central Southern Alps, the Mackenzie Lakes; Ohau, Pukaki and Tekapo, occupy fault Figure 3: Map of Lake Ohau showing the location of the three cores we controlled glacial valleys and contain high resolution sedimentary compare our models to. daily rainfall records of the last ~17 ka. These sediments potentially contain a 1/1/70 modelled suspended record of climatic events and transitions, earthquakes along the Alpine sediment load Fault to the northwest, landscape response during and following deglaciation and recent human-influenced land use changes.