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Determining the influence of supraglacial debris on the characteristics of runoff from glaciers in Switzerland
As climate warms, diurnal variations in proglacial discharge are expected to increase. Debris-covered glaciers have different hydrographs, with smaller amplitudes and longer time-lags. This thesis will characterize the runoff for debris-free and debris-covered glaciers in Switzerland.
The area of supraglacial debris has been observed to increase over glaciers (Bolch et al., 2008; Bhambri et al., 2011; Lambrecht et al., 2011) and this pattern is likely to continue in the future as glaciers slow and thin due to increasingly negative mass balances (Kirkbride and Deline, 2013). Currently it is expected that as climate warms the diurnal amplitude of glacial runoff would increase due to an earlier retreat of the snowline and hence a longer period of ice melt (Escher-Vetter and Reinwarth, 1994). However, there is emerging evidence that glaciers with a significant debris cover have distinct proglacial hydrograph characteristics, specifically a smaller amplitude, longer lag time from peak air temperature to peak runoff and a reduction in the number of peaked diurnal hydrographs compared to clean glaciers (e.g. Li et al., 2016). Therefore, increasing glaciers’ debris-cover may have the opposite effect on hydrographs to what is currently expected, which has implications for water resources and especially run-of-river hydropower schemes.
The area of supraglacial debris has been observed to increase over glaciers (Bolch et al., 2008; Bhambri et al., 2011; Lambrecht et al., 2011) and this pattern is likely to continue in the future as glaciers slow and thin due to increasingly negative mass balances (Kirkbride and Deline, 2013). Currently it is expected that as climate warms the diurnal amplitude of glacial runoff would increase due to an earlier retreat of the snowline and hence a longer period of ice melt (Escher-Vetter and Reinwarth, 1994). However, there is emerging evidence that glaciers with a significant debris cover have distinct proglacial hydrograph characteristics, specifically a smaller amplitude, longer lag time from peak air temperature to peak runoff and a reduction in the number of peaked diurnal hydrographs compared to clean glaciers (e.g. Li et al., 2016). Therefore, increasing glaciers’ debris-cover may have the opposite effect on hydrographs to what is currently expected, which has implications for water resources and especially run-of-river hydropower schemes.
This study will analyse a large dataset of proglacial flow records in Switzerland using a consistent approach, enabling determination of the influence of supraglacial debris on the runoff hydrograph and flow duration curves. More specifically, you will determine the hydrograph characteristics (in terms of shape, timing and amplitude) of runoff from glaciers in Switzerland, then quantify the influence of secondary variables (catchment and glacier size, mean elevation, mean air temperature and mean precipitation rate) on the hydrograph characteristics. You will then statistically determine the influence of supraglacial debris on the proglacial runoff characteristics and quantify the overall difference in the standardised flow duration curve between debris-covered and debris-free glaciers.
This study will analyse a large dataset of proglacial flow records in Switzerland using a consistent approach, enabling determination of the influence of supraglacial debris on the runoff hydrograph and flow duration curves. More specifically, you will determine the hydrograph characteristics (in terms of shape, timing and amplitude) of runoff from glaciers in Switzerland, then quantify the influence of secondary variables (catchment and glacier size, mean elevation, mean air temperature and mean precipitation rate) on the hydrograph characteristics. You will then statistically determine the influence of supraglacial debris on the proglacial runoff characteristics and quantify the overall difference in the standardised flow duration curve between debris-covered and debris-free glaciers.
For further information please contact Dr. Francesca Pellicciotti (francesca.pellicciotti@wsl.ch) or Dr. Evan Miles (evan.miles@wsl.ch)
For further information please contact Dr. Francesca Pellicciotti (francesca.pellicciotti@wsl.ch) or Dr. Evan Miles (evan.miles@wsl.ch)