The effect of climate on the fluvial system has long been investigated due the significant
impact it can have on a river’s hydrological regime and fluvial processes. In recent years
this interest has increased as global changes in climate are expected to bring more
frequent high magnitude flood events globally and to North West Europe in particular.
Despite the knowledge that the frequency and magnitude of floods is to increase, less is
known about the geomorphological implications of this for river channels and where
channel instability is likely to occur at both the river network and national scale. This is
certainly the case in Scotland where increased flooding is expected and large floods have
been abundant over the last two decades. To manage Scottish river catchments effectively
in the future, in terms of hazard mitigation and nature conservation, river managers need
to be able to predict not only how climate will impact flood magnitude and frequency in
Scotland but the effect these changes will have on the internal dynamics of river channels
in terms of erosion, sediment transport and deposition, and morphological dynamics.
Such knowledge will ensure adequate measures are implemented to reduce fluvial risks
to humans and to maintain and preserve valuable river habitats and linked species.
In this thesis, several novel methods incorporating field, laboratory and GIS-based
analysis, have been investigated as a means of predicting how climate change will affect
channel stability in Scottish rivers and the implications of this for river management and
river ecology. This includes (i) analysing the potential change in the frequency of
geomorphologically-active flood flows with climate change; (ii) the use of stream power
thresholds to predict changes in channel stability on a national scale with climate change;
and (iii) using a Digital River Network developed using geospatial data to predict changes
in the rate of bedload transfer and channel stability with climate change. Studies were
undertaken on 13 different rivers across Scotland from north to south and east to west.
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As a case study of ecological implications, the thesis also examines how changes in
habitat and stability of freshwater pearl mussels (Margaritifera margaritifera) may be
altered by increased flooding. Predictions of the frequency of geomorphic activity,
channel stability, rate of bedload transfer, and the stability of freshwater pearl mussel
habitat with climate change are discussed along with the methods used to obtain these
outcomes.
The results all suggest an increase in the frequency and rate at which bedload is
transferred through the river system and an increased frequency of flood flows resulting
in greater channel instability. Morphological responses vary spatially with some river
reaches experiencing greater increased erosion and transport potential than others.
Climate change effects on the freshwater pearl mussel are: increased occasions of
disturbance and transport downstream and the importance of specific populations in more
stable environments for ensuring population recovery post flooding is highlighted. It is
hoped that the methodologies developed for predicting changes in channel stability with
climate change will provide useful screening tools to regulatory agencies which can be
developed further to assist management decisions in the future which aim to reduce fluvial
hazards and maintain good quality river environments for the species that inhabit it. The
approaches used in this study allow for the identification of areas at high risk of
morphological and ecological change, and the pro-active planning and management of
sediment-related river management issues and nature conservation.
Date of Award | 2017 |
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Original language | English |
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Awarding Institution | |
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Supervisor | David Gilvear (Other Supervisor) |
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- Freshwater Pearl Mussel
- Channel Stability
- Stream Power
- Climate Change
CHANGING FLOOD FREQUENCY IN SCOTLAND: IMPLICATIONS FOR CHANNEL GEOMORPHOLOGY, ECOLOGY AND MANAGEMENT
Thompson, F. H. (Author). 2017
Student thesis: PhD