Water Quality Of Perlis River Environmental Sciences Essay

Malaysia is enriched by abundance of natural resources and one of them is the rivers or also known as surface water. River or surface water is precious and vital natural resource for all life on Earth especially human being as it provides water supply for human domestic use, irrigation for agriculture, as a means of transportation, industries use and so on. Even though there always has been plenty of fresh water in Malaysia, clean water supply has not always been available due to the rising water pollution problem.

Nowadays, Malaysia has become an industrialized country and no longer left behind the other developed countries but at the cost of the environment. Effluent from the industrial area which is then discharged directly into the rivers without prior treatment is the main sources of water pollution. Besides, human activities such as the uses of agricultural chemicals, soil erosion due to improper development project, land use and so on are also contributed significantly to water pollution (Niemi et al., 1990). Pollution of river with high concentration of toxic chemicals and excess nutrients, which are resulting from surface water runoff, leaching from landfill site and ground water discharges has been aroused the public concern towards the water pollution issue. Thus, there is a need to assess river or surface water quality due to the increased understanding of the importance of water quality towards public health and aquatic life (Ying, 2005).

Peninsular Malaysia consists of 11 states and two federal territories whereas Perlis is the smallest state among them. Perlis state is situated at the northwest of peninsular Malaysia. There are more than ten major rivers within the Perlis area while Perlis River is one of the most important rivers in Perlis. The length of the Perlis River is approximately 11 km through Kangar city to Kuala Perlis while the size of the river basin is approximately 310 km². Perlis River has become the center stage for the public to socialize and for recreational activities particularly at Denai Larian Sungai Perlis. The number of visitors who are visiting to the river and surrounding area for rest and recreation purpose is estimated to be achieved 10,000 peoples per month. However, the quality of Perlis River does not reach the desired level and it is much difference if compared to the major rivers at developed countries.

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There are some problems which occurred at Perlis River at present. According to the Interim National Water Quality Standards for Malaysia, the status of water quality at Sungai Perlis is classified as Class III. There is heavy erosion occurred at Perlis River and leading to the river banks become very shallow. Residents which located surrounding the river have thrown rubbish or solid waste into the river therefore causing to unaesthetic scene and it is not accessible to boats. Besides, there is a landfill located in Kuala Perlis and this directly affects the water quality of the river when the leachate is leaching out. Squatters located near the river reserve area are also causing pollution problems and there is a need to regular patrols or hut-to-hut checks. Other point source pollution such as shrimp livestock ponds, Kangar wet market, esplanade at Perlis River, food stalls and the Kuala Perlis fisherman jetty are contributed significantly to the water pollution at Perlis River. (www.1s1rcommunity.net)

On the other hand, the sources of water pollution can be categorized into point and non-point sources. Point sources of pollution refer to those easily identifiable pollutants which enter the water resource though a direct route, for example, effluent from wastewater treatment plants. Whereas for non-point source pollution, it refer to those pollutants which enter from diffuse sources and they are difficult to control, such as stormwater runoff (P.Jamwal et al., 2008).

In this study, Mann-Kendall trend test and principal component analysis (PCA) have been applied to detect the trends of water quality data and to obtain the most significant parameters in order to trace the sources of pollutants. Mann-Kendall trend test is one of the most widely used non-parametric tests to detect significant trends in time series. It has the advantage that their power and significance are not affected by the actual distribution of the data (Hamed, 2009). Therefore it is more suitable for detecting trends in hydrological time series, which are usually skewed and contained the outliers.

Mann-Kendall trend test has been widely used in assessing the variability on hydrological time series (Hamed, 2008). The examples of earlier studies which applied Mann-Kendall technique are trend study and assessment of surface water quality in the Ebro River (Bouza-Deano et al., 2008), hydrological trend analysis due to landuse changes at Langat River basin (Juahir et al., 2010), identification of hydrological trends at Canadian Rivers (Khaliq, 2009) and so on.

Principal component analysis (PCA), one of the multivariate statistical techniques, is helps in reducing redundant parameters with minimum loss of original information (Helena et al., 2000). A better understanding of water quality can be achieved through the interpretation of complex water quality data matrices. Besides, it allows the identification of possible factors or sources that affect water systems and therefore a reliable management of water resources as well as swift solution to pollution problems can be found out (Vega et al., 1998; Wunderlin et al., 2001; Reghunath et al., 2002; Simeonova et al., 2003; Simeonov et al., 2004).

In recent years, principal component analysis (PCA) has been applied in various aspect of field including environmental issues. It has been used to characterize and assess water quality data, and it is efficacious in verifying temporal and spatial variations caused by natural and anthropogenic factors (Helena et al., 2000; Singh et al., 2004, 2005). The examples of application of PCA in environmental issues are interpretation of ground water hydrographs (Winter et al., 2000), examination of spatial and temporal patterns of heavy metal contamination (Shine et al., 1995) identification of herbicide species related to hydrological conditions (Tauler et al., 2000) and so on.

The aims of this study are to detect the trends of water quality data at Perlis River and determine the significant parameters that contributed to water pollution by using Mann-Kendall and principal component analysis techniques. A deeper understanding of the evolution in water quality from the year 2003 until year 2007 can be achieved via the Mann-Kendall trend test. Besides, by using the principal component analysis (PCA), the sources of pollutants can be traced and thus some mitigation measures can be carried out.