Assessment of water quality and source of pollution for some selected rivers in southern region of Bangladesh

Abstract

Rivers are important for mankind. They provide water for economic development and human consumption; they provide recreational facilities; they support a large variety of wildlife and they are part of our natural scenic heritage. Industrial development, improvements in living standards and change in agricultural practice have resulted in an increased demand for good quality water. However, such developments have produced increased amount of sewage, industrial wastewater, agricultural discharge and agricultural runoff. The rivers that flow through almost all of the world’s cities shown an appreciable decline in water quality but these are often difficult to specify the exact cause of the deterioration. Khulna division is situated in the south western part of Bangladesh, its area is about 22274 sq.km and the population is about 14.47 million. It has 10 districts and 28 municipalities in Khulna division. Khulna Formed with the silted alluvial soil. This division is fertile and produces a lot of coconut, paddy, jute, betel leaf, sugarcane, potato, turmeric, oil seeds, mulberry plant, vegetables, mango, jackfruit, banana, litchi, berry, palm and papaya. The world biggest mangrove forest is found in Sundarban. Khulna is also known as the city of Shrimps, because 75% of all shrimps exported from Bangladesh are cultivated in the Khulna zone. This study was conducted depending on secondary data of some extensive laboratory tests which were performed by to DoE to determine the physical and chemical of some selected rivers (Bhairab , Kakshially, Garai, Rupsha, Poshur, Mouri, Mamundo, Kopotakha, Mathavanga) in Southern region of Bangladesh. The river water was found to be highly turbid and higher loading of BOD and COD in both Pre-monsoon and Monsoon period. This indicates that the bacteriological pollution load as compared to flow was very high in the both season. Also the pollutant load in downstream of the river and far away from the place of the major activities of the conveyor, were less. At the same time source of pollution were identified for the surrounding area.