JCBPS; Section D; August 2020 –October 2020, Vol. 10, No. 4; 393-398. E- ISSN: 2249 –1929 [DOI: 10.24214/jcbps.D.10.4.39398.] Journal of Chemical, Biological and Physical Sciences An International Peer Review E-3 Journal of Sciences Available online atwww.jcbsc.org Section D: Environmental Sciences CODEN (USA): JCBPAT Research Note Studies on the water qualities of the Dhalai River Tripura, India Jibesh Datta and Rahul Das Department of Civil Engineering, Tripura Institute of Technology, Tripura, India; Received: 29 August 2020; Revised: 10September 2020; Accepted: 16 September 2020 Abstract: Tripura is a tiny state with geographical area of 10,486 km2, situated in the North- Eastern Region of India and surrounded by Bangladesh on three sides.The Dhalai River (also known as Dhala River) a trans-boundary river in India and Bangladesh. It rises in the mountains of the Indian state of Tripura. It enters Kulaura Upazila of Maulvi Bazar District of Bangladesh. Later it joins Manu River in Rajnagar Upazila. The co- ordinates of Dhalai River at Ambassa are 23.55'128'' N and 91.51'204'' E in degrees minutes seconds (DMS). It originate from Atharamura Hill and is 117 kilometres (73 mile) long. Some of the popular riverside township of Dhalai River are Ambassa town, Baralutma and Kamalpur town. Water quality of lakes, rivers and reservoirs in developing countries like India is being degraded because of the contaminated inflows and surrounding influence. There is a serious need for appropriate water quality monitoring for future planning and management of Lake and other type of water resources. Quality of water in the Dhalai River, Tripura, India has been investigated in this paper. Water Quality Index (WQI) was applied in the Dhalai River India using water quality parameters like pH, Turbidity, Conductivity, Hardness, Alkalinity, Dissolved Oxygen, Biochemical Oxygen Demand and Nitrate. Tests were performed on site using electronic measuring device as well as on Laboratory with samples of water collected from different locations of the Dhalai River. It shows that water quality of the Dhalai 393 J. Chem. Bio. Phy. Sci. Sec. D ; August 2020 –October 2020, Vol. 10, No. 4; 393-398. DOI:10.24214/jcbps.D.10.4.39398.] Studies on … Jibesh Datta and Rahul Das. River falls within the good water ‘category but marginally’. Continuous monitoring of the Dhalai River is suggested for proper management. Keyword:pH; Water Quality Index; Turbidity; Biochemical Oxygen Demand; Hardness; 1. INTRODUCTON The well-known fact is that the existence of life on the earth is mainly due to presence of water. It provides sustenance to plants, animals, aquatic organisms and support human needs likes agriculture and industries. From ancient times, rivers are used as fresh water resources for human beings [1,2]. The quality of usable water is degrading due to the overexploitation caused by increase of population and its anthropogenic activities. Water bodies get polluted regularly by the dumping of domestic, hospital and industrial wastes. On the other hand, our religious rituals are also responsible for water quality deterioration as most of the rituals are performed near the bank of river and water bodies [3,4]. Majority of our population believes in idolatry and idol immersion has become a cause of water pollution during festive seasons. Water pollution caused by idol immersion has social, religious, scientific and environmental dimensions. Idols are made of clay, clothes, straw, bamboo, plaster of paris, nails and are decorated by natural and synthetic paints and colors. The constituting materials of idols degrade the quality of water on immersion [5]. Tripura, one of the north-eastern states of India, situated in the eastern part of India and surrounded by Bangladesh on the West, South and North side. Only North-eastern and Eastern boundaries are separated by Assam and Mizoram respectively. The state lies between 22°56' to 24°32' North latitudes and 91°09' to 92°20' East longitudes spread over 10,491.69 sq. km. with population as per the 2011 census data is about 3,671,032. The State is characterised by a warm and humid sub-tropical climate with five distinct seasons namely, spring, summer, monsoon, autumn and winter [6]. The average annual maximum and minimum temperatures are 38 and 10 ºC respectively with average annual rainfall recorded is about 1,881mm. Tripura is well gifted with surface water resources and all major rivers of Tripura bring about from hill ranges and occurrences like typical lattice and dendrite pattern. During rainy season the river water being in flurry while in summer month they remain almost in dry condition [7]. Out of ten major rivers in the state, River Dhalai is the lifeline of Ambassa city because it fulfills the major demand of drinking water as well as water for other purposes of the entire population of the city. Formerly Dhalai river water was pollution free due to less anthropogenic interferences. But nowadays numbers of inhabitants on the banks of the river are increasing very rapidly which deteriorates the quality of river water and put it into a distressing condition [8,9]. Objective of the study:Considering the physical, historical, administrative and economic importance of the area this study is directed towards the identification and assessment of environmental condition and man environment relationship of the study areas of Dhalai river basin area. The main objectives of the study area are as follows: To identify the environmental conditions along the Dhalai river. To determine the physio-chemical and biological properties of Dhalai river water. To identify the problems and environmental perception of the habitant along Dhalai river. 394 J. Chem. Bio. Phy. Sci. Sec. D ; August 2020 –October 2020, Vol. 10, No. 4; 393-398. DOI:10.24214/jcbps.D.10.4.39398.] Studies on … Jibesh Datta and Rahul Das. 2. MATERIALS AND METHODS Study Area: The study area of Ambassa, government hospital site in Dhalai River, Ambassa, Tripura is geographically located at Latitude: 23º 55´ 04´´ N and Longitude: 91º 51´ 11´´ E. Figure 1 showing the location taken up for study in the Dhalai River. Figure 1: Sampling Site To study the water quality of Dhalai River during. the water samples were collected from surface area water during morning hours at different intervals.All samples were collected in high density polypropylene bottles (Teflon make) which were cleaned properly first with dilute nitric acid and then with distilled water. The measurement of temperature and fixation of dissolved oxygen were completed at the site and analyses of other parameters were carried out in the laboratory of Department of Civil Engineering, Tripura Institute of Technology, Agartala. These samples were subjected to analyze the physiochemical parameters like pH, Temperature, Dissolved oxygen, Total hardness, Total alkalinity, Biochemical Oxygen Demand, Total dissolved Solids, Total Suspended solids etc. 3. RESULT AND DISCUSSION 3.1. Observations: To apprehend the nature of some changes in the physical and bio-chemical behavior of the river I have tried to find out the nature and extent of different natural and anthropogenic activities. Rural use:The people of Dhalai district in catchment, of the Dhalai River are engaged in agricultural practice and for this they are collecting water from the river by using pump.The people living along the bank of the river Dhalai are using the river water for their domestic use like washing clothes, utensils etc. Fishing is one of the most important economic activities in the river Dhalai. Due to the deterioration of water quality as well as the lowering of water level this activity is being threatened to 395 J. Chem. Bio. Phy. Sci. Sec. D ; August 2020 –October 2020, Vol. 10, No. 4; 393-398. DOI:10.24214/jcbps.D.10.4.39398.] Studies on … Jibesh Datta and Rahul Das. a greater extent. Urban use: People live near the channel for obtaining drinking water. The source of that purified drinking water to the inhabitants is also the River Dhalai. It was observed during the survey that there are three water purifying pumps along the channel and the source of water of those pumps from Dhalai River. In the whole catchment area of the Dhalai basin it has been noticed that there is a tendency of using the river side as toilet. But few toilets have been found directly joined with the river. Various solid wastes dumped by the market area and the inhabitants who are living along the channel have been found. The river water also heavily polluted through the chemical pollutants that the water turns green, say become green soup, due to phenomenal growth of algae and phytoplanktons in the river water. 3.2. Physiochemical Parameters: Dissolved Oxygen (DO): Oxygen absorbed by water from the atmosphere and standard natural water should have a DO content of 6 mg/l, depending on the standard temperature of about 200C. Depletion of DO indicates utilization by organic and inorganic compounds, i.e. contamination from domestic and industrial wastes. It was found that the DO values of four sites were below the standard limit (BIS: 6 mg/l). If DO is above standard value (6 mg/1) water quality is good. The DO values of the four sites were ranged from 6.8 mg/l to 6.34 mg/l. Bio-chemical Oxygen Demand (BOD):The amount of oxygen required by the organic matter in sewage to undergo aerobic decomposition is known as BOD (Biochemical Oxygen Demand). Thus, more BOD content indicates more amount of sewage disposal. From the tables it may be seen that the Bio-chemical Oxygen Demand (BOD) values of sites of the riverwere higher than the standard limit (BIS: 3 mg/l) and ranges from 1.2 mg/l to 2.6 mg/l and the BOD value of rest sites were within the standard limit and ranges from 1.2 mg/l to 2.6 mg/l.