Lake Waves and Gravel Beach Variation, Loch Lomond, Scotland

Pierce, Lydia R (1997) Lake Waves and Gravel Beach Variation, Loch Lomond, Scotland. PhD thesis, University of Glasgow.

Abstract

Lake waves and gravel beach variation, Loch Lomond Scotland. Keywords: beach variation; gravel beaches; lake beaches; waves; sediment budget; restricted fetch. Beaches respond morphologically to changes in wave conditions, water level and sediment supply. As coastal sediment stores, which reflect the terrestrial hydrological process balance, beaches are very sensitive to environmental change. However, controls on beach variability are not yet fully understood. In comparison to sand or mixed sand/gravel beaches, gravel beach response to environmental changes is muted. Low-energy gravel beach adjustments to external controls remain poorly understood. This research investigates gravel beach variation within a relatively low energy upland lake environment in mid-high latitudes (Loch Lomond). To assess the nature of the lake wave climate, waves were recorded throughout 1994 and statistical and spectral analysis performed. The wave climate is distinctive, characterised by small amplitude, high frequency waves and periods of calm. Water levels fluctuate and showed clear seasonal trends with bi-annual periods of rapid rise/fall. Water levels are a fundamental control on beach variability, both in rates of fluctuation and in that they provide the underlying control on the effects of waves. The research was largely field-based and gravel beach variability was examined with respect to morphological and sedimentological change and sediment budgets for two beaches were calculated. Fluvial sediment delivery was modelled from peak monthly stage. Cliff recession and beach morphology were surveyed to show highly variable longshore beach characteristics which are closely related to beach elevation, exposure and sediment supply. Sections of beach represented by individual profiles type showed profile types may persist from month to month. Sedimentology was examined for the sub-aerial and sub-aqueous beach into the offshore. Cross beach offshore fining was observed, with a clear abrupt limit to coarse sediment in the nearshore. Fluvial discharge exerts a significant control on beach development as it affects sediment entrainment and delivery, distribution and storage within the beach. Water level is also significant in sediment redistribution. The deltas are major sediment stores within the beach sediment budgets often for long time periods (years). At high water levels deltaic sediments are often below wave base and are therefore not entrained and transported. This limits sediment availability for beach morphological readjustment and shore defence. This research is important for the understanding of sediment-poor, low energy beach behaviour and response to changing environmental conditions. The research has implications for modelling lake gravel beach sediment transport and storage mechanisms. It also highlights the need for appropriate management strategies for lake coastal environments.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Jim Hansom
• Keywords: Physical chemistry, Physical geography
• Date of Award: 1997
• Depositing User: Enlighten Team
• Unique ID: glathesis:1997-75567
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 19:25
• Last Modified: 19 Nov 2019 19:25
• URI: https://theses.gla.ac.uk/id/eprint/75567