Remote sensing and landscape assessments

For my final year dissertation I completed research which examined the role of remotely sensed satellite imagery in carrying out Landscape Character Assessments (LCAs).  Although geographical information systems (GIS) are acknowledged as powerful tools for conducting LCAs, the role of remote sensing and image processing had not been extensively considered in previous research.

A LCA is a tool which is commonly used by planning authorities to account for the impact a development might have on the surrounding landscape.  For example, a huge multi-storey car-park would probably be found to be highly inappropriate for a rural village because it would degrade the aesthetics of the area.  LCAs can also be used to examine nuisances in an area.  For my project, I carried out a brief LCA of Courtmacsherry Bay, Co. Cork.  This estuary was an interesting study site because it has been plagued by an infestation of sea lettuce in recent years, as evident by the image below.  Sea lettuce is a green algae, and has been growing prolifically in the estuarine waters of Courtmacsherry Bay as a result of nitrogen and phosphorus enrichment.  The source of the nutrients is debated, however.  Some suggest the nitrogen and phosphorus are coming from agricultural land-use, while others claim they are originating from human waste.  Regardless of the source, the algal bloom is a menace to tourists and locals alike.  Not only does it prevent aquatic recreation in the area, as the algae becomes stranded and decomposes, noxious odours are produced.  The LCA methodology was adopted to assess the impact the sea lettuce was generating; however, the primary function of the LCA was to use it as a basis to consider the contribution satellite imagery and image processing could make to strengthening the findings of future assessments.

An image recorded in October 2012 which demonstrates the extent of the sea lettuce infestation in Courtmacsherry Bay.

An image recorded in October 2012 which demonstrates the extent of the sea lettuce infestation in Courtmacsherry Bay.

A traditional LCA is carried out by conducting a desk study which relies on secondary data, then field work, then consultations with stakeholders (often experts rather than people affected), and finally conclusions are drawn from the assessment’s findings.  The LCA I carried out used data from the GeoEye-1 satellite.  Field visits included recording photos and perceptions of the area.  Questionnaires were also distributed to local residents and an interview was carried out to acquire a detailed understanding of the area.  One interview was sufficient because the LCA was only being used as a baseline for comparative analysis; if, however, the LCA was being used by a planning authority, it is likely that many more respondents would be needed.  Once the information and data were acquired, the findings were analysed and discussed.

Chart providing a visual representation of how many km2 each land class occupies.  The sea lettuce infestation covers 0.21km2 of the image which is 17.6%.

Chart providing a visual representation of how many km2 each land class occupies. The sea lettuce infestation covers 0.21km2 of the image which is 17.6%.

Satellite image processing operates on the understanding that every surface (vegetation, infrastructure, water etc.) reflects different amounts of solar radiation.  This is why we see various things in different colours.  Using an image processing software package, it is possible to highlight surfaces and classify them.  By doing this, a researcher can quantify the amount of land an activity or feature occupies.  The pie chart on the right demonstrates how this can be visually represented.  For instance, 17.6 per cent of the area these data refer to was covered by sea lettuce.  This suggests that the sea lettuce is a considerable concern for the study site.  In quantifying land use and cover, scientific rigour can back up and strengthen qualitative (views and opinions) findings from questionnaires and interviews.

The outcomes of the questionnaires and interview could have easily been predicted: the sea lettuce infestation was undeniably a nuisance.  What could not be predicted was the level of damage the algae was causing.  Boats’ rudders, for example, were being destroyed, costing one respondent thousands of Euro.  Although people’s views are a major part of social research, some consider qualitative research “soft” because it is often considered non-replicable and unreliable.  At the same time, methodologies like environmental risk assessments (ERA) are criticised because relying solely on scientific data omits the people who will be directly affected by the results of the research.  As a result, the conclusion of my research found that a combination of subjective qualitative information and scientifically quantifiable data provided an excellent holistic view of the concern being addressed.

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About GeeMcAuliffe

Geography graduate predominately interested in agriculture's connection with the physical environment. Currently studying for a PhD in Geography and Environmental Science at University College Cork. I believe methods from the natural and social sciences can complement each other and that the two realms should not be mutually exclusive. Previous research I undertook examined the role of remote sensing and image processing in landscape character assessments and considered the benefits of including quantitative satellite image processing in a largely qualitative methodology. My current research involves carrying out an environmental risk assessment of commericial pig units on rivers in Co. Cork, Ireland, to examine the links between pig production and water quality. When I'm not working on my research, I usually entertain myself by playing or watching rugby, watching TV shows (True Detective, Breaking Bad, Game of Thrones, Mad Men etc.), watching films (big fan of Tarantino and David Lynch), or gaming. I also enjoy cooking and, more importantly, eating what I cook.
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