## 2 Methods
### Sieve Analysis  
GPR has been used in this study to understand the shallow subsurface of natural and anthropogenic coastal landforms. However, GPR facies are not equal to sedimentary facies. To correctly recognize the sedimentary characteristics, it is common to combine the detection of sedimentary strata with sediment sample analysis because the grain size distribution can reveal the characteristics of a dynamic sedimentary environment more accurately. Soil reconstruction is the core technique of land reclamation. As artificially assembled soil, the spatial distributions of reclaimed soil properties are different from those of natural soil since the parent materials of reclaimed soil are highly random. Therefore, the different grain size distribution patterns can indicate natural and anthropogenic coastal landforms, respectively [34]. Sieve analysis is a procedure to sort the grain size according to their diameters settled through a mechanical technique according to its weight [35]. The sieve materials were acquired by taking samples from the survey area. The samples were taken randomly but along the site's survey lines, using a cylinder bottle as a container, and placed into a plastic bag. Five sediment samples were collected from the Batu Ferringhi site, then another five were collected from the Queensbay Mall parking lot site. The raw data of these ten sediment samples can be accessed online (open access) from [[https://doi.org/10.5281/zenodo.4395](https://doi.org/10.5281/zenodo.4395)]([https://doi.org/10.5281/zenodo.4395](https://doi.org/10.5281/zenodo.4395)) 755, accessed on 11 April 2021. In the laboratory, the samples were placed in a beaker and washed with water. The samples were stirred using a spatula, and these steps were repeated a few times until it became apparent few impurities remained. The water was then removed. In the next step, the samples were dried in a drying oven set at 80 \({}^{\circ}\)C for 2 to 3 days. After the samples were completely dry, the dried samples was set up for sieving. The sieves' empty weight is determined as sieves with increasing mesh size are put on the pan. The sample is weighed and placed on the uppermost sieve, which is \(-2.5\,\Phi\) unit. The complete sieve stack was then placed on the sieve shaker and fastened. Ten minutes sieving time on the sieve shaker was set, and when the sieving time has stopped, the collecting pan and the fraction on it were weighed. The mass of each fraction is determined, recorded, and calculated in the Microsoft Excel application, then plotted on a graph. Figure 3: Survey lines of GPR at site 2, Persiaran Bayan Indah, Bayan Lepas representing anthropogenic coastal landform, plotted on Google Earth (2015), Persiaran Bayan Indah, Penang, Malaysia. The coordinates for the initial point of survey lines (\(\bullet\)) is \(05^{\circ}19^{\prime}57.19^{\prime\prime}\) N and \(100^{\circ}18^{\prime}30.23^{\prime\prime}\) E. Digital-Globe 2015. [[http://earth.google.com](http://earth.google.com)]([http://earth.google.com](http://earth.google.com)) (accessed on 3 February 2015). The most straightforward task for the grain analysis from the graph is the measurement of the central tendency, which is commonly measured for sieved samples as a central tendency, including median, mode, mean, kurtosis, and skewness. The frequency curve measures the central direction, including median, mode, and mean [36]. Percentages of coarse grain or fine grain can show up significantly as horizontal limbs at the ends of the curve. Cumulative curves are powerful to express sorting. Sorting is the tendency for the grains to arrange in one class of grain size. Half of the particles by weight are coarser than the median and half are finer, so the the diameter corresponds to the cumulative frequency curve's 50% value. It may be expressed either in phi (\(\Phi\)) or in millimeters (mm). The mode is the most frequently-occurring particle diameter corresponding to the steepest point on the cumulative curve. It also corresponds to the highest point on the distribution curve.