This thesis presents results from spatial-temporal and volumetric change analysis
of blowouts on the Cape Cod National Seashore (CCNS) landscape in Massachusetts,
USA. The purpose of this study is to use methods of analysing areal and volumetric
changes in coastal dunes, specifically blowouts, and to detect patterns of change in order
to contribute to the knowledge and literature on blowout evolution.
In Chapter 2.0, the quantitative analysis of blowout change patterns in CCNS was
examined at a landscape scale using Spatial-Temporal Analysis of Moving Polygons
(STAMP). STAMP runs as an ArcGIS plugin and uses neighbouring year polygon layers
of our digitized blowouts from sequential air photo and LiDAR data (1985, 1994, 2000,
2005, 2009, 2011, and 2012 for 30 erosional features, and 1998, 2000, 2007, and 2010 for
10 depositional features).
The results from STAMP and the additional computations provided the following
information on the evolution of blowouts: (1) both geometric and movement events occur
on CCNS; (2) generation of blowouts in CCNS is greatest in 1985 and is potentially
related to vegetation planting campaigns by the Park; (3) features are expanding towards
dominant winds from the North West and the South West; (5) the erosional and
depositional features are becoming more circular as they develop, (6) the evolution of CCNS blowouts follows a similar pattern to Gares and Nordstrom’s (1995) model with
two additional stages: merging or dividing, and re-activation.
In Chapter 3.0, the quantitative analysis of volumetric and areal change of 10
blowouts in CCNS at a landscape scale is examined using airborne LiDAR and air
photos. The DEMs of neighbouring years (1998, 2000, 2007, and 2010) were differenced
using Geomorphic Change Detection (GCD) software. Areal change was detected by
differencing the area of polygons that were manually digitized in ArcGIS. The changes in
wind data and vegetation cover were also examined. The results from the GCD and areal
change analysis provide the following information on blowout evolution: (1) blowouts
generate/initiate; (2) multiple blowouts can merge into an often larger blowout; (3) and
blowouts can experience volumetric change with minimal aerial change and vice versa.
From the analyzes of hourly Provincetown wind data (1998-2010), it was evident that
blowouts developed within all three time intervals. The percentages of comparable winds
(above 9.6 m s-1) were highest in 1998, 1999, 2007 and 2010. It is speculated that tropical
storms and nor'easters are important drivers in the development of CCNS blowouts. In
addition, supervised classifications were run on sequential air photos (1985 to 2009) to
analyze vegetation cover. The results indicated an increase in vegetation cover and
decrease of active sands over time. Two potential explanations that link increased
vegetation to blowout development are: (1) sparse vegetation creates a more conducive
environment for the initiation of blowouts by providing stability for the lateral walls, and
(2) high wind events (e.g. hurricanes and nor'easters) could cause vegetation removal,
allowing for areas of exposed sand for blowout initiation and development. / Graduate / 0799 / 0368 / kimia.abhar@gmail.com
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVIV.1828/5311 |
| Date | 29 April 2014 |
| Creators | Abhar, Kimia |
| Contributors | Walker, Ian J. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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