Sampling in Geographical Fieldwork Using GIS Techniques , pp. 4 of 6

From the remote sensing image results in Figure 5, at Cha-am beach (‘low erosion sites’), the remote sensing imagery results show that there is no significant, observable coastline retreat from the years 2008 to 2016. The three lines (representing Cha-am coastlines in the three years – 2008, 2012 and 2016) are very much overlapping one another, which indicates that there is no significant coastline retreat or advancement recorded at that area. On the other hand, from Figure 5, at Cha-am south beach (‘high erosion sites’), the remote sensing imagery reveals that there were changes in the coastline along Cha-am south beach from 2008 to 2016. The results show that certain sections along Cha-am south beach underwent coastline retreat from 2008 to 2012 and then to 2016. Results also showed that other sections further south of Cha-am south beach experienced an advancement of coastline from 2008 to 2012, followed by a subsequent retreat of coastline from 2012 to 2016, The coastline in 2016 exhibited the most extreme retreat.

Interviews, Beach Profiling and Sediment Analysis On-Site

Due to the GIS remote sensing techniques, it was therefore possible to identify in advance, the sites for data collection. The on-site data collection included beach profiling, sediment analysis and semi-structured interviews with the locals living along Cha-am’s coastline at the two selected sites of high and low erosion.

Two transects were marked out, one located at Cha-am beach and the other located at Cha-am south beach. Along each transect, three sand samples were collected at L1, L2, L3 and H1, H2, H3, at 0 m, 4 m and 8 m from the high water mark respectively (Figure 7). The collected sand samples were then sieved and analysed. In addition, beach profiling was done at the same two transects.

The sediment analysis results from Table 1 reveal that the sediments collected from the transect at Cha-am south beach generally comprised of coarser and larger sediments, while the sediments collected from the transect at Cha-am beach comprised of finer and smaller sediments. Using the sediment size analysis data along with the remote sensing data (Figure 5) that shows coastline retreat indicates that the areas with highest coastline retreat and erosion (i.e. Cha-am south beach) was found to have coarser and larger sediments, while the areas with no significant coastline retreat and erosion (i.e. Cha-am beach) was found to have finer and smaller sediments. This suggests that the more erosive beaches (i.e. Cha-am south beach) generally comprised of coarser and larger sediments, which could be associated with the increased intensity of the selective winnowing of the finest fractions of sediments and the progressive coarsening of the resulting lag deposit (Guillen and Jimenez, 1995). In contrast, the less erosive beaches generally comprised of finer and smaller sediments, since the waves do not have as much energy to transport the larger and coarser materials up onto the shore.

An Inspiring Quote

"[Open-mindedness] includes an active desire to listen to more sides than one; to give heed to facts from whatever source they come; to give full attention to alternative possibilities; to recognize the possibility of error even in the beliefs that are dearest to us."

~ John Dewey, How We Think

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