Application of Multivariate Statistical Analysis in Evaluation of Surface River Water Quality of a Tropical River

Abstract

The present study evaluated the spatial variations of surface water quality in a tropical river using multivariate statistical techniques, including cluster analysis (CA) and principal component analysis (PCA). Twenty physicochemical parameters were measured at 30 stations along the Batang Baram and its tributaries. The water quality of the Batang Baram was categorized as “slightly polluted” where the chemical oxygen demand and total suspended solids were the most deteriorated parameters. The CA grouped the 30 stations into four clusters which shared similar characteristics within the same cluster, representing the upstream, middle, and downstream regions of the main river and the tributaries from the middle to downstream regions of the river. The PCA has determined a reduced number of six principal components that explained 83.6% of the data set variance. The first PC indicated that the total suspended solids, turbidity, and hydrogen sulphide were the dominant polluting factors which is attributed to the logging activities, followed by the five-day biochemical oxygen demand, total phosphorus, organic nitrogen, and nitrate-nitrogen in the second PC which are related to the discharges from domestic wastewater. The components also imply that logging activities are the major anthropogenic activities responsible for water quality variations in the Batang Baram when compared to the domestic wastewater discharge.

Analysis of Groundwater Nitrate Contamination in the Central Valley: Comparison of the Geodetector Method, Principal Component Analysis and Geographically Weighted Regression

“…PCA reduces the dimensions of data by using a linear combination of variables to capture the maximum variance in the data [29][30][31]. The principal scores for each component can also be calculated, which are then used as the independent variables to build the predictive model [32][33][34] or compare it with other variables of interest [35]. The correlation matrix between the variables and the loadings of each variable in the principal components are used to investigate the contamination process in the study area.…”

Assessment of Near-Bottom Water Quality of Southwestern Coast of Sarawak, Borneo, Malaysia: A Multivariate Statistical Approach

“…Logging activities in the surrounding area have caused sedimentation and increased suspended solids level in the river and subsequently into the coastal area. Reference [9] demonstrated that logging was the main factor in regulating water quality of Sarawak forest streams compared to sewage discharge. In the present study, the Sarawak coastal water quality demonstrated different trend where dwellings, aquaculture, and agriculture were the major source compared to logging activities.…”

“…In the present study, the Sarawak coastal water quality demonstrated different trend where dwellings, aquaculture, and agriculture were the major source compared to logging activities. This is most probably due to the study in [9] that was conducted in inland freshwater forest streams which were subjected to active logging activities and lower population densities. Phosphorus enrichment in Sarawak coastal water was described in PC3 and PC4 with positive loadings on IP, TP, and OP.…”

“…Although deterioration of the coastal environment due to increasing population and urbanization is noticeable in Sarawak [6], the study conducted on Sarawak coastal water is scarce. Aquaculture and domestic sewage with high nutrients content is being discharged directly into rivers [7] while deforestation for timber production and agricultural development has increased soil erosion and inputs of fertilizers in Sarawak River [8,9], all of which could lead to increased sedimentation and eutrophication in coastal areas.…”

“…Among them, cluster analysis (CA) and principal component analysis (PCA) have been applied in the assessment of spatial variation of tidal river and freshwater forest streams water quality in Sarawak [7,9,22]. However, the study on Sarawak coastal water quality is scarce; and the application of CA and PCA for the assessment of the Sarawak coastal water quality has not yet been conducted.…”