Fusion of airborne LiDAR, multispectral imagery and spatial modelling for understanding saltmarsh

278 Pages·2016·17.15 MB·English

Fusion of airborne LiDAR, multispectral imagery and
spatial modelling for understanding saltmarsh
response to sea-level rise

PhD

Miriam Fernández Núñez

Coastal and Estuarine Research Unit
Department of Geography, University College London

A thesis submitted for the degree of
Doctor of Philosophy
May 2016

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To S.L. & E.L.

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Declaration

I, Miriam Fernández Núñez, confirm that the work presented in this thesis is my own.
Where information has been derived from other sources, I confirm that this has been
indicated in the thesis.

25 May 2016

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Acknowledgement

My first thoughts go to my supervisors Dr. Helene Burningham and Dr. Jon French for their
guidance, support, patience and kindness throughout this PhD. In particular, I wish to
thank Helene who has invested a lot of her time guiding me from the very beginning and
has paid very detailed attention to every aspect of my work. Her experience, knowledge
and enthusiasm have been a source of inspiration, and I really valued and enjoyed the time
that we spent discussing different matters integrated in this PhD. My second thoughts go
to my Spanish tutor Dr. Jose Ojeda Zujar (University of Sevilla) for his guidance and
support, and providing important data for this PhD. Thanks also to my colleagues in the
Department of Geography at University College London, especially Darryl, Katerina, Jose,
Sam, Charlotte, Mandy, TV, Pooya and other PhD students for our discussions and their
encouragement during lunch time and coffee breaks. Thanks also to my colleagues in the
Department of Geography at University of Seville, Natalia, Arsenio, Inma, Pablo, Noela,
Antonio, Jose and other colleagues for their help and support during my time in Spain.
Particularly, I would like to thank to Antonio (el topografo), J. Antonio (el teniente), Jesus
Pedrero, and the manager and workers of the ‘Paraje Natural Marismas del Odiel’ for their
help during my field work, and Paco and Cesar Borja for their advices about bibliography
and support. Thanks to my family for their unconditional support, especially to my mum.
Thanks also to Uncle John Barker for his help and advices throughout this PhD. Warm
thanks to Naoko Lam and Pilar Diaz for their support and for helping me to look after my
wonderful daughter Sophie, without them I could not have finished this PhD on time. A
special thanks to my wonderful husband for his support and encouragement during all
these years. He has been a key person at the beginning and the end of my thesis, and his
criticism helped me to improve my academic writing.
Finally, I acknowledge the two research projects that this work has benefited from:
one funded by the Spanish National Research Plan and European Regional Development
Fund (ERDF) (“Detail mapping and web dissemination of demographic, tourist and
environmental data for vulnerability assessments linked to beach erosion in the Andalusia
Coast (sea-level rise associated to climate change)”; CSO2010-15807) and the other one by
Andalusia regional government (“Espacialización y Difusión Web de Datos de
Urbanización, y Fitodiversidad para el Análisis de Vulnerabilidad ante los Procesos de
Inundación Asociados a la Subida del Nivel del Mar en la Costa Andaluz”; RNM-6207).

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Abstract
Coastal ecosystems are considered to be sensitive to changes in environmental forcing,
particularly sea-level rise. Saltmarshes occupy a discrete lateral and vertical position that
is fundamentally controlled by the position of sea level, but the nature of other factors
such as broader scale shoreline dynamics and anthropogenic ensure that the nature and
extent of sea-level rise impacts on saltmarshes are globally variable, and locally complex.
Thus, there is a need to understand these controls and to predict the potential response of
saltmarsh systems to sea-level change at the local scale. The present research presents a
multifaceted methodology for investigating the response of saltmarshes due to sea-level
rise at local scales with application to the Odiel saltmarshes (SW-Spain), using elevation
data derived from Light detection and ranging (LiDAR), high spatial resolution
multispectral imagery and spatial modelling, that in combination with historical estuary
evolution and field observation can be applied for effective management and conservation
of saltmarshes in the context of sea-level change. SLAMM (Sea Level Affecting Marshes
Model) has been used to evaluate coastal wetland habitat response to sea-level rise
Accurate model spatial model inputs such as digital elevation models (DEMs) and
saltmarsh habitat map are essential to reduce uncertainties in the model outputs, and part
of this thesis has been focused on improving accuracy in saltmarsh elevation and habitat
maps. Additionally, a sensitivity and uncertainty analysis was undertaken to explore first
the relative importance of data quality and resolution (spatial and vertical) in the
elevation data and saltmarsh habitat classification layers, and then the global uncertainty
of the model outputs using a Monte Carlo approach. Our findings suggested that model is
sensitive to DEM and habitat map resolution, and that historical sea-level trend and
saltmarsh accretion rates are the predominant factors that influence uncertainty in
predictions of change in saltmarsh habitats.

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