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Svalbard tidewater glaciers are retreating, which will affect fjord circulation and ecosystems when glacier fronts become land-terminating. Knowledge of the subglacial topography and bathymetry under retreating glaciers is important to modelling future scenarios of fjord circulation and glacier dynamics. We present high-resolution (150m gridded) digital elevation models of subglacial topography, ice thickness, and ice surface elevation of five tidewater glaciers in Kongsfjorden (1100 km(2)), northwestern Spitsbergen, based on similar to 1700 km airborne and ground-based ice-penetrating radar profiles. The digital elevation models (DEMs) cover the tidewater glaciers Blomstrandbreen, Conwaybreen, Kongsbreen, Kronebreen, and Kongsvegen and are merged with bathymetric and land DEMs for the non-glaciated areas. The large-scale subglacial topography of the study area is characterized by a series of troughs and highs. The minimum subglacial elevation is 180m above sea level (a.s.l.), the maximum subglacial elevation is 1400m a.s.l., and the maximum ice thickness is 740m. Three of the glaciers, Kongsbreen, Kronebreen, and Kongsvegen, have the potential to retreat by similar to 10 km before they become land-terminating. The compiled data set covers one of the most studied regions in Svalbard and is valuable for future studies of glacier dynamics, geology, hydrology, and fjord circulation.

Engabreen is an outlet glacier of the Svartisen Ice Cap located in Northern Norway. It is a unique glacier due to the Svartisen Subglacial Laboratory which allows direct access to the glacier bed. In this study, we combine both sub- and supraglacial observations with ice-flow modelling in order to investigate conditions at the bed of Engabreen both spatially and temporally. We use the full-Stokes model Elmer/Ice and satellite-based surface-velocity maps from 2010 and 2014 to infer patterns of basal friction. Direct measurements of basal sliding and deformation of lower layers of the ice are used to adjust the ice viscosity and provide essential input to the setup of our model and influence the interpretation of the results. We find a clear seasonal cycle in the subglacial conditions at the higher elevation region of the study area and discuss this in relation to the subglacial hydrological system. Our results also reveal an area with an overdeepening where basal friction is significantly lower than elsewhere on the glacier all year round. We attribute this to either water pooling at the base, or saturated sediments and increased strain heating at this location which softens the ice further.

Engabreen is an outlet glacier of the Svartisen Ice Cap located in Northern Norway. It is a unique glacier due to the Svartisen Subglacial Laboratory which allows direct access to the glacier bed. In this study, we combine both sub- and supraglacial observations with ice-flow modelling in order to investigate conditions at the bed of Engabreen both spatially and temporally. We use the full-Stokes model Elmer/Ice and satellite-based surface-velocity maps from 2010 and 2014 to infer patterns of basal friction. Direct measurements of basal sliding and deformation of lower layers of the ice are used to adjust the ice viscosity and provide essential input to the setup of our model and influence the interpretation of the results. We find a clear seasonal cycle in the subglacial conditions at the higher elevation region of the study area and discuss this in relation to the subglacial hydrological system. Our results also reveal an area with an overdeepening where basal friction is significantly lower than elsewhere on the glacier all year round. We attribute this to either water pooling at the base, or saturated sediments and increased strain heating at this location which softens the ice further.

Recent studies have likened the seasonal observations of ice flow at the marginal regions of the Greenland Ice Sheet (GrIS) to those found on smaller alpine and valley counterparts. These similarities highlight the need for further small scale studies of seasonal evolution in the hydrological and dynamic structure of valley glaciers, to aid interpretation of observations from the margins of the GrIS. This thesis aims to collate a large suit of glacio-hydrological data from the outlet glacier Engabreen, Norway, in order to better understand the role the subglacial drainage configuration has on surface velocities recorded at the site. The Svartisen Subglacial Laboratory (SSL) under Engabreen, augmented by additional subglacial pressure and hydrological measurements, provides a invaluable observations for detailed process-oriented studies. However, the lack of complementary surface velocity data complicates comparisons with other surface-oriented glaciohydrological studies. One major aim of this thesis is to provide a longer record of surface velocity, enabling a more complete understanding of the glacial hydro-mechanical relationship at Engabreen. In order to extend the velocity dataset here, a time-lapse camera based study was carried out, providing seasonal velocity maps over a large portion of an inaccessible region of the glacier. The processing and feature tracking of terrestrially based imagery, in order to obtain quantitative velocity measurements, is challenging. Whilst optical feature tracking has a relatively long history in glaciology, the availability of adaptable terrestrial georectifiaction and feature tracking tools is somewhat limited. A key achievement of this thesis is the development of a new, comprehensive, georectification and feature tracking toolbox, ImGRAFT. This adaptable tool performs both rectification of the time-lapse camera imagery, and feature tracking. The resulting velocity estimates are able to capture seasonal changes in