Temperature and bathymetry of ice‐contact lakes in Mount Cook National Park, New Zealand

Abstract

Several ice-contact lakes have formed in conjunction with twentieth century glacier retreat in Mt Cook National Park. They occupy overdeepened glacial valleys and are dammed by terminal moraines and/or outwash heads. During the autumns of 1994 and 1995, the temperature and bathymetry of "Maud lake", "Godley lake", and Hooker Lake were surveyed. The near-glacier vertical water temperature profiles exhibited greater temperature variation than those at the distal ends of the lakes. Thermal stratification existed in Hooker Lake, whereas both Maud and Godley lakes were thoroughly mixed. Water temperatures in the latter were consistently between 3 and 4.5°C, but most parts of Hooker Lake were cooler than 2°C, with a minimum recorded temperature of 0.2°C. These contrasts are important because melting of submerged parts of glacier termini is significant for ablation rates and for the dynamics of calving termini. All the lakes are steep sided and deep. Maud and Godley lakes approach 100 m in depth, whereas Hooker Lake has a maximum recorded depth of 136 m. Extensive flat floors in Maud and Godley lakes probably reflect rapid sediment accumulation following glacier retreat. Water depth at the termini of iceberg-calving glaciers is known to correlate strongly with rates of iceberg production and hence the rate of glacier retreat. However, given the substantial water depths through which these glaciers (and also the neighbouring Tasman Glacier) have retreated, they appear to be more stable than comparable glaciers in other countries. The subaqueous geometry of all the glacier termini comprises a projecting ramp of glacier ice. All the lakes are being enlarged by glacier retreat except Maud lake, which has been reduced in size since 1995 by the advance of Maud and Grey Glaciers.

Annual ice volume changes 1976–2008 for the New Zealand Southern Alps

“…Bathymetric data has been used for the pro-glacial lake at Tasman glacier terminus from 2003 (Röhl, 2006) and at Godley glacier from 1994 (Warren and Kirkbride, 1998). Volume errors from this source are likely to be less than +/−10%.…”

“…Ice margin recession at the glacier terminus is calculated directly from photographic records of lake growth that have been documented since 1980 (Chinn, 2002) and from bathymetric measurements (Warren and Kirkbride, 1998;Röhl, 2006,;Hochstein et al, 1998). Detailed rates of ice calving into lakes are also available for the Hooker and Tasman Glaciers (Kirkbride, 1993;Hochstein et al, 1995Hochstein et al, , 1998Kirkbride and Warren, 1999;Purdie and Fitzharris, 1999;Kääb, 2002;Röhl, 2006).…”

Onset of calving at supraglacial lakes on debris-covered glaciers of the Nepal Himalaya

“…Warren and Kirkbride (1998), Benn and others (2001) and Haresign and Warren (2005) have also observed the thermal undercutting rate. The above results by several researchers suggest that thermal undercutting acts as a trigger for lacustrine calving.…”

The Schmidt hammer as a relative‐age dating technique: Potential and limitations of its application on Holocene moraines in Mt Cook National Park, Southern Alps, New Zealand

“…1,3). The snout of the Hooker Glacier (which has 25.1 % of its surface covered in debris) is actively calving into a c. 0.75 km 2 proglacial lake that has been enlarging since the late 1980s (Warren & Kirkbride 1998). As a result of a series of years with positive net balance, the retreat of Hooker Glacier has recently slowed down and ceased (Chinn pers.…”