PhD Research
PhD Research Project:
Host Institute:
Institute of Earth Surface Dynamics (IDYST), Faculty of Geosciences and Environment, University of Lausanne, Switzerland [details]
Scholarship and Funding Agency:
Swiss Government Excellence Scholarship funded by the Federal Commission for Scholarships (FCS)
Thesis Title:
Influence of climate change influence on water resources in Alpine and Himalayan river basins using tree rings and stable isotope analyses
Summary of the Project:
Mountains are the ‘water towers’ that deliver freshwater to millions of people living downstream. Despite their importance, mountain regions are data-poor with complex terrain that makes space-time transferability of knowledge related to climate change impacts on water resources difficult. As a result, we know very little about past environmental variabilities in the high-altitude mountain basins. Therefore, to plug this data gap, this thesis aims to unlock the impacts of climate on tree growth and the stable isotope compositions of the tree rings for tracing changes in water resources in the Alpine and Himalayan river basins by addressing the following research questions:
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How does climate impact local temperature and precipitation conditions, and hence influence tree growth across the elevational gradient in Alpine environments?
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Can we use intra-annual (earlywood and latewood) information including isotope variations in tree rings to understand seasonal changes in the growth of trees and the relationship to water use in Alpine environments?
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Can the tree rings be used to reconstruct past history of river flow in a poorly gauged/ ungauged river in the Eastern Himalaya?
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Is it possible to detect the changing water sources for tree growth using annually resolved tree-ring stable isotope compositions in poorly gauged mountain river basins?
To answer these research questions, two specific methodologies have been used; (1) standard dendrochronology procedures for tree ring chronology building followed by reconstructing paleohydrology (e.g., streamflow), and (2) tree ring stable isotope analysis to improve our knowledge of how intra-annual ring growth and isotopic compositions respond to seasonal variations in temperature and precipitation in an Alpine river basin having a parent glacier and a hydropower dam upstream, as well as in the unexplored glacierised Himalayan river basin.
Figure: Steps involved in sample pre-processing; starting from tree-coring (a), followed by gluing, mounting and drying them in room temperature (b), sanding selected samples (c), slicing remaining samples using a core-microtome (d), and scanning all samples using a prototype machine called “Skippy” (e) to produce digital images (f).
This research proides useful evidence of how climate change has significant consequences on tree growth and streamflow variabilities in the high-altitude glacier-fed river basins. These findings have important implications for sustainable management of freshwater resources in the Alpine and Himalayan River basins.
