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Space is used as a proxy for time in determining the role of glaciation in shaping valley cross profiles in the Two Thumb Range (Southern Alps), New Zealand. The range is undergoing rapid tectonic transport and uplift as it is advected toward the Alpine fault. Repeated cycles of glacial erosion during the Quaternary have fashioned U-shaped valleys in the north of the range, close to the Main Divide, while valleys in the less glaciated south of the range have rounded divides and convex fluvial cross profiles. Tectonic transport and uplift rates, coupled with an offshore oxygen isotope [[delta].sup.18]O) record and glacialgeological reconstructions, allow time constraints to be applied to valley development along the range. Valley width and depth measurements and power-law equations were used to quantify the shape of cross-profile transects in 37 valleys. Valleys evolved into a characteristic U-shaped cross profile formed over [greater than or equal to] 400 k.y. of glacial occupancy. This, regardless of other models of glacial flattening of valley long profiles, suggests that alpine glaciation excavates greater volumes of rock, indicating that glaciers are a more effective erosional agent than fluvial activity in alpine mountain belts. Keywords: glacial valleys, morphology, landscape evolution.

Glacier melt is an important source of water for Andean rivers in central Chile, especially in dry years when it can be the main contributor to lowland flows in late summer and autumn. However, few studies have quantified the glacier melt contribution to river runoff. To address some of these shortcomings, we present an analysis of meteorological conditions and melt for Universidad glacier, a large valley glacier in the Mediterranean climate central Andes of Chile at the head of the Tinguiririca river, for the 2009-2010 ablation season. We used meteorological measurements from two automatic weather stations installed on the glacier to drive a distributed temperature-index melt and runoff routing model, and compare total modelled glacier melt to river flow measurements at three sites located between 0.5 and 50 km downstream. The temperature-index model was calibrated at the lower weather station site showing good agreement with melt estimates from an ablation stake and sonic ranger, and with a physically-based energy balance model. Universidad glacier is characterized by extremely high melt rates over the ablation season which exceed 10 m water equivalent on the lower altitude part of the glacier, representing a contribution between 10 % and 13 % of the total runoff observed in the upper Tinguiririca basin during the November 2009 to March 2010 period. This contribution rises to a maximum of 34 % in late summer demonstrating the importance of glacier runoff to river flow, particularly in dry summers such as 2009-2010. The temperature-index approach benefits from the availability of on-glacier meteorological data and is suited to high melt regimes, but would not be easily applicable to glaciers further north in Chile where sublimation is more significant. [ABSTRACT FROM AUTHOR]

This paper describes a point surface energy balance model which runswithin the Microsoft Excel spreadsheet package. The study incorporates a large amount of previous energy balance work and presents it in a useable form. The core model calculates the net shortwave and longwave radiation fluxes, the turbulent sensible and latent heat fluxes and the surface melt rate at a point on a melting ice or snow surface,from hourly inputs of incoming shortwave radiation, vapour pressure,air temperature and wind speed data. The latitude, longitude, slope angle, aspect, elevation, local temperature lapse rate, albedo and aerodynamic roughness of the study site, and the elevation of the meteorological station, can all be specified in the model. An output file containing the hourly and daily rates, and the totals of the energy fluxes is generated. The main advantages of the model are: first, thatit requires only a PC or laptop computer running standard Microsoft Windows software, enabling it to be used at a desktop or in the field; and second, that it can be adapted quickly to different sites, meteorological data formats and other application requirements. Model calculations are compared with measured surface melt rates at five points on Haut Glacier d'Arolla, Switzerland, over a 115 day ablation period. Allowing for differences in shading between the meteorological station and the glacier, the root mean square error of the calculated melt rates is 270 mm day-1 water equivalent melt (mean error +172 mm day-1), for measured melt rates in the range 23 to 42 mm day-1 water equivalent melt. [ABSTRACT FROM AUTHOR]