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- Description:
- Classification of barrier island morphology stems from the seminal work of M. O. Hayes and others, which linked island shape to tidal range and wave height and defined coastal energy regimes (i.e., wave-dominated, mixed energy, tide-dominated). If true, this general relationship represents a process-based framework to link modern and ancient systems, and is key for determining paleomorphodynamic relationships. Here we present a new semi-global database of barrier islands and spits (n = 702). Shape parameters (aspect, circularity, and roundness) are used to quantify island boundary shape, and assess potential correlation with coastal energy regime using global wave and tide models. In adopting the original energy classification as originally put forth (i.e., wave dominated, wave-influenced mixed, tide-influenced mixed, tide dominated), results show that wave-dominated islands have statistically different mean shape values from those in the mixed energy fields, but the two mixed energy designations are not distinct from each other. Furthermore, each energy regime field contains a wide range of island shapes, with no clear trends present. Linear regression modeling shows that tidal range and wave height account for < 10% of the documented variance in island shape, a strong indication that other controls must be considered. Therefore, while energy regime distinctions can be used descriptively, their utility in predicting and constraining island shape is limited: barrier island shape is not indicative of coastal energy regime, and vice versa. Our analysis also demonstrates empirical scaling relationships among modern barrier islands for the first time, with implications for subsurface prediction. and This is the dataset of the Modern Barrier Island Database published in Mulhern et al., 2017 Marine Geology paper titled "Is Barrier Island Morphology a Function of Wave and Tide Regime?" with the DOI https://doi.org/10.1016/j.margeo.2017.02.016. If using this dataset please cite both the dataset and the paper.
- Keyword:
- paleomorphodynamic relationships, geology, barrier island, shallow marine, island shape, wave-dominated islands, shoreline morphology, Modern Barrier Island Database, and coastal geomorphology
- Subject:
- Geology
- Creator:
- Johnson, Cari L., Mulhern, Julia S., and Martin, John M.
- Owner:
- Julia Mulhern
- Language:
- English
- Date Uploaded:
- 09/08/2021
- Date Modified:
- 06/03/2024
- Date Created:
- 2015-01-01 to 2017-12-31
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50d-5pzj-r9vr
-
- Description:
- Subglacial water pressures influence groundwater conditions in proximal alpine valley rock slopes, varying with glacier advance and retreat in parallel with changing ice thickness. Fluctuating groundwater pressures in turn increase or reduce effective joint normal stresses, affecting the yield strength of discontinuities. Here we extend simplified assumptions of glacial debuttressing to investigate how glacier loading cycles together with changing groundwater pressures generate rock slope damage and prepare future slope instabilities. Using hydromechanical coupled numerical models closely based on the Aletsch Glacier valley in Switzerland, we simulate Late Pleistocene and Holocene glacier loading cycles including long-term and annual groundwater fluctuations. Measurements of transient subglacial water pressures from ice boreholes in the Aletsch Glacier ablation area, as well as continuous monitoring of bedrock deformation from permanent GNSS stations helps verify our model assumptions. While purely mechanical glacier loading cycles create only limited rock slope damage in our models, introducing a fluctuating groundwater table generates substantial new fracturing. Superposed annual groundwater cycles increase predicted damage. The cumulative effects are capable of destabilizing the eastern valley flank of our model in toppling-mode failure, similar to field observations of active landslide geometry and kinematics. We find that hydromechanical fatigue is most effective acting in combination with long-term loading and unloading of the slope during glacial cycles. Our results demonstrate that hydromechanical stresses associated with glacial cycles are capable of generating substantial rock slope damage and represent a key preparatory factor for paraglacial slope instabilities.
- Keyword:
- Aletsch Glacier, boreholes, numerical models, subglacial water pressure, Switzerland, Late Pleistocene, Holocene, ground water, and geology
- Subject:
- Geology
- Creator:
- Moore, Jeffrey R., Loew, Simon, Limpach, Philippe, Gischig, Valentin, Grämiger, Lorenz, and Funk, Martin
- Owner:
- Jeff Moore
- Based Near Label Tesim:
- Aletsch Glacier, Valais, Switzerland
- Language:
- English
- Date Uploaded:
- 01/03/2020
- Date Modified:
- 10/29/2024
- Date Created:
- Borehole P1 2013-07-12 09:28:09 to 2014-08-08 09:11:14 and Borehole P2: 2013-07-16 05:00:03 to 2014-08-08 22:10:44
- License:
- CC BY NC - Allows others to use and share your data non-commercially and with attribution.
- Resource Type:
- Dataset
- Identifier:
- https://doi.org/10.7278/S50D-A50H-3TE4