A study of spatial and water quality index during dry and rainy seasons at Kelantan River Basin, Peninsular Malaysia

A study was conducted to identify the water quality status of Kelantan River Basin, Peninsular Malaysia, covering five sub-catchments (Nenggiri, Galas, Lebir, Pergau, and Kelantan downstream (DS)) during the dry and rainy seasons. Water samples were collected from 27 sampling stations along the Kelantan River at the years 2017 and 2018. The data consists of temperature, pH, total suspended solid (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia nitrogen (AN), nitrate (NO), phosphorus (P), and manganese (Mn). The water quality status was identified by calculating the water quality index (WQI) based on the National Water Quality Standards for Malaysia (NWQS) using six parameters. The study explores the spatial approach in assessing water quality status to produce an assessment index. Results showed that water quality status during the dry season at Kelantan River Basin was in class III for all sub-catchments, where the water can only be used for livestock drinking and tolerant species of fishes. Meanwhile, the quality of the water during the rainy season was in class III for the sub-catchments of Lebir, Pergau, and Kelantan DS. The Galas’ sub-catchment was in class IV, and the Nenggiri’s sub-catchment was experiencing the worse condition (in class V). Overall, the water quality in the Kelantan River Basin is at a moderate level, whereby more focus on the Nenggiri’s and the Galas’ sub-catchments should be take it seriously to ensure that the river water pollution levels in Kelantan are well under control.