Pollution monitoring at Sungai Semantan tributaries using georaphical information system

Abstract

The availability of fresh water for human use has become a problem due to climate change scenario. This study aims to assess the water quality patterns of pollution concentrations in Sungai Semantan catchment using GIS. This spatial pattern of each parameter was then analysed based on the Water Quality Index (WQI) and National Water Quality Standards (NWQS) to determine the locations of major pollutant sources that contribute to water quality depletion in the Sungai Semantan catchment. The considerations of sampling were focused on land use data that contributes to high potential impact to water quality. The water sampling was collected from nine different locations of the Bentong region starting from Sungai Bentong and Sungai Kelau to Sungai Semantan in the sunny and rainy seasons from November 2016 to April 2017. The samples collected were then analysed for different physicochemical parameters including pH, TSS, DO, BOD, COD, NH3-N, turbidity, colour, iron and manganese to determine the spatial distribution of water quality in the study area. Geo-statistical analysis and Geographical Information System (GIS) were used to visualize the spatial pollution characteristics and identify potential polluted risky regions. From the obtained results of the parameters characteristics, it can be concluded that the water in Sungai Semantan is disturbed due to the presence of BOD, COD, TSS, turbidity, colour, iron and manganese concentrations. This parameter was exposed to various pollutants and seriously exceeded the standard of Category III (refer Malaysia NWQS). However, based on WQI, most of the parameters measured remained in Class II ranged from 85.12 to 90.11 (mean 88.13). In this study, the final representation of WQI has been done on the GIS map to show the spatial variation of pollution levels in the entire Sungai Semantan catchment. It is suggested that monitoring should be carried out continuously for proper management of this river basin to ensure sustainability of the water supply. WQI calculation formula should be reviewed by authorities to ensure important water quality parameter is relevant to analysis.