Assessment of water quality of selected rivers in Bangladesh using fews software

Abstract

River water quality is a key concern for Bangladesh as river water is essential for drinking and domestic purpose, survival of aquatic life and also for the development of industries and agriculture. Unfortunately, due to rapid urban expansion and industrialization along with the absence of proper water management practices, the water quality of rivers in Bangladesh, particularly around Dhaka city, is deteriorating rapidly. Therefore, it is very important to improve the water quality of the rivers surrounding Dhaka and protect them from further pollution. Currently, the development of effective pollution prevention strategies is impeded by a number of factors, including inadequate monitoring of water quality and poor analysis of collected water quality data by the concerned government authorities. This study endeavors to assess the current pollution status of the major rivers around Dhaka City by using a new monitoring technology, Delft-FEWS software developed by Deltares. In this study, water quality data of the rivers Buriganga, Balu,Turag, Shitalakhya, and Meghna were collected from the Department of Environment (DoE) and Bangladesh Water Development Board (BWDB). Available data of the parameters pH, EC, DO, TS, TDS, TSS, Cl, BOD5 and COD, recorded during the period 2002-2017 from several monitoring stations of DoE and BWDB, were imported to FEWS Bangladesh System, a customized version of Delft-FEWS software. Temporal and spatial variation of the water quality of the rivers under the study were analyzed using the time series graphs and spatial maps displayed by the system based on the imported data. The study has found that FEWS system is an effective water quality monitoring tool which made it easy to identify the spatial and temporal nature of pollution. The time series and spatial data presented in the study indicate that, the water quality status of the rivers surrounding Dhaka (Buriganga, Turag, Shihitalakkhya and Balu) has deteriorated more in recent years than during the last decade. For all the rivers around Dhaka, high fluctuation of the BOD5, COD, Chloride, EC, TDS and TSS value was observed between dry and wet season. During dry season, the rivers were found extremely polluted with significantly lower DO level and higher BOD5 and COD value than the acceptable level. However, the other parameters e.g., Chloride, EC, TDS, TSS and pH were found within acceptable limits. The pollution level was found relatively higher at Kamrangirchar, Dholaikhal and Sadarghat stations of Buriganga river whereas a similar pollution trend was observed at all stations of Tuarg and Balu river. However, in case of Shitalakhya river, the stations at the lower reach were found more polluted than the upper reach. In contrast to the peripheral rivers of Dhaka, the water quality of Meghna river has been found suitable for all types of uses with acceptable level of DO and BOD5 in the river water. This research has investigated the recent pollution conditions of the major rivers around Dhaka and insight into the effectiveness of FEWS system as an innovative monitoring tool. Hence, the research may be used as a good reference for the concerned authorities in upgrading the existing water quality monitoring system and developing strategy for pollution prevention and protecting the rivers.