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The purpose of this paper is to evaluate the performance of the spline interpolation method in predicting and mapping the concentration of Total Suspended Solids (TSS) in the surface water of Pulau Tuba, Kedah. Thirty sampling points were set up and geolocated using the Geographic Positioning System (GPS). Gravimetric analyses were used to determine the TSS level. Fifty percent of the total sampling points were randomly chosen for developing spatial models using regularised and tension spline methods. The research found that the tension spline methods outperform the regularised spline method. The Mean Squared Error (MSE), Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), and Mean Absolute Error Percentage (MAPE) were reported at 351.641, 18.752, 15.81, and 21.51%, respectively. This study’s findings are critical in the domains of spatial statistics and interpolation for creating a precise map of water properties.

Interpolation map of salinity is a helpful scientific instrument for environmental monitoring and for social economic development especially for the community who lived in Sungai Merbok. This research was conducted to develop a spatial model of salinity using spline interpolation technique. 20 sampling stations were randomly set up to measure the level of salinity using YSI 650 Multiparameter Display System (MDS). Quantitative analysis of standard regression and error index were used to evaluate the developed model. The research found that the tension splines type performed better than regularized splines type. The local government and community, who live in Sungai Merbok, can use the developed map of salinity for guidelines and future development of Sungai Merbok, Kedah.

This study aims to assess the characteristics and occurrence of the microplastics contamination in surface sediment of Selat Pulau Tuba, Langkawi, Kedah. Van Veen Grab Sampler was used to collect the samples of sediment. The samples were immediately preserved and analyzed using a Fourier-transform infrared spectrophotometer and a microscope to determine the presence and characteristics of microplastics. The result indicates the presents of polypropylene and polyethylene with a size of 500 µm -1000 µm and 1000 µm - 1500 µm respectively. Overall, Selat Pulau Tuba, Langkawi, Kedah has minimal pollution of microplastics in sediment.

This research is conducted to assess the accuracy of spline interpolation methods to predict and model the surface water pH of Pulau Tuba, Langkawi, Kedah, Malaysia. In-situ sampling activities using pH-meter and Geographic Positioning Systems (GPS) were carried out during high tides and at noon in November 2018. The development of spatial models was constructed using Regularized and Tension spline methods. Then, validation of models was carried out to compare the observed and predicted values of pH using correlation analysis, regression analysis, and error analysis. The accuracy of the developed map was calculated using the overall accuracy equation. This research found that the regularized spline method had more accuracy in estimating surface water pH variability than the tension spline method. Pearson correlation coefficient (r), Coefficient of determination (R2), Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) were reported at 0.896, 0.803, 0.0265 and 0.0344 for the regularized spline method,respectively. The developed spatial model was then transformed into a map by adding map elements such as legend, title, north arrow, and scales for effective visualization. The developed map has an accuracy of 87.50%. The surface water pH was found at the range of 7-8. Low reading of pH is expected due to the addition of rainwater to the coastal water of Pulau Tuba, Langkawi, Kedah. The research outcomes would benefit government and non-government agencies to monitor the coastal and ocean acidification and the development of strategic policies and rules to reduce the impact of anthropogenic activities and climate changes for this area.