Saturday, April 12, 2008

Grain size distribution analysis at Chek Jawa

Remember the post made in February regarding Studying substrate variability in Chek Jawa by GIS? It is a team effort made by Yikang, Yong Jian and Jing Kai from NUS Geography department. They went out in February to collect sediments from the transects my project was doing. More about their adventures in my CJ project blog and Ria's wildfilms blog.

The team has done up a website: where you can conveniently have access to their work. It's interactive, informative and beautiful! Here's some screenshots from the webpage.

The homepage of the website shows the grain size distribution using a Google Map. It was done using GIS applications on the sediment data collected from the transect. I like how you can click on the right side the different sediment size classes and the distribution will be shown on the Google Earth image. Try exploring around to find out more.

You can get to know more about their background, study area, sorting of sediments and most importantly the objectives. To summarise, the main objective will be to gain an insight into the coastal processes affecting the beach at Chek Jawa, in particular the grain size sorting process and the variables that influence this phenomenon. Importantly, this project aims to show that GIS aids in data collection, visualization and manipulation.

If you are curious how they conducted their study, feel free to read more about their sampling, sieving and interpolation method. I believe you will be amazed how technology can aid in research, especially in the area of GIS, which in this project can help to do interpolations of grain distribution in Chek Jawa.

Analysis of results mainly show:

1. Velocity of less than 0.5 m/sec in this area (Wong, 1985) may prove to be significant as from the Hjulstrom curve would imply sediments between 0.01 mm and 0.15 mm may be affected due to sufficient energy of the tidal streams

2. Presence of river indicates source of sediments as well as a counteracting force to the long shore current

3. The sand bar may be the resultant feature of the tidal flow and the river flow due to the lowering of energy levels

4. Selective sorting may also have taken place as can be seen from the progressive reduction in grain sizes further away from the river where fluvial influence is the greatest (Self, 1977)

The last segment explains more about GIS, their limitations, and conclusion.

The team ended off with "This case can serve as a starting point which can be expanded to the other beaches in Singapore, especially in context of the heavy modifications to the coastline in recent years. Knowing how sand grains are sorted can possibly give an idea of the energy level of a particular beach environment (Nordstrom, 1977). This will have implications on the methods of beach protection employed. For instance, predicting the possible morphological changes to the beach should beach nourishment activities take place will help in determining the effectiveness of the activities."

Find out more about their work here:

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