The glaciers in the McMurdo Dry Valleys (MDV) melt very little. Glacial melt is the

main source of water for the streams that transport freshwater and nutrients to the

terminal lakes. In this harsh environment, a microbial ecosystem relies on the freshwater

for survival. Currently, MDV glaciers are in stable equilibrium and melt very

little compared to other alpine glaciers. However, the melt regime currently rests

on the threshold of change in this warming world. It is anticipated that changes to

glacial melt will affect the survival and biogeography of the microbial communities.

Thus, a key challenge is to resolve the atmospheric controls on glacial melt and

streamflow to understand how future climate may impact hydrological connectivity.

To do so, a novel hydrometeorological modelling system was adapted to simulate

cold-based glacial melt on a MDV glacier. The modification of the meltwater percolation

scheme to allow near-surface runoff enabled the non-negligible contribution of

small-scale melt processes to seasonal runoff to be resolved. In addition, the spectral

albedo scheme parameters were optimized to simulate snow-albedo-melt feedbacks

for the first time on a MDV glacier. Accurately simulating albedo is vital, as net

shortwave radiation is the primary driver of melt in this energy-limited environment.

Adapting and testing the hydrometeorological modelling system at a point-scale laid

the foundation to model spatially distributed mass balance and streamflow in Taylor

Valley. This is the first modelling system capable of simulating sub-diurnal scale

streamflow variability at ecologically relevant timescales. By bridging glacial melt

to streamflow, the differences in the meteorological drivers on streamflow over two

seasons are explained. Furthermore, it was found that the second key driver of melt,

the sensible heat flux, can generate a similar amount of total seasonal streamflow

over a single event to a season driven by frequent, smaller, net shortwave radiation

driven melt events. The application of the modelling system was extended to investigate

the sensitivity of streamflow to future atmospheric warming and increased

snowfall. Increasing mean air temperatures resulted in a non-linear increase in total

runoff in Taylor Valley by approximately 39%, 90% and 240% for an increase of 0.5,

1 and 2°C, respectively. In addition, increasing air temperatures by only 1°C ensured

the sensible heat flux was positive (towards the surface) over the glaciers in Taylor

Valley. Increased snowfall led to decreased streamflow in cases where the snow was

enough to raise the albedo and trigger a cooling regime. However, in other cases,

snowfall contributed to increased streamflow through a greater mass turnover. This

is due to the relatively warmer and wetter air masses. These air masses decrease the

gradient between the surface and atmosphere, reduce the turbulent heat fluxes, and

result in more energy being available for melt. The research findings of this thesis

demonstrate the sensitivity of hydrological connectivity in the MDV to atmospheric

processes and the urgent need for regional-scale climate projections for this region

on the cusp of change.