International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 06 | June -2018 www.irjet.net p-ISSN: 2395-0072 © 2018, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 775 Assessment of Spatial Variations of Water Quality Index of Deepor Beel, Assam, India Sewali Kalita 1 , Himadri Kalita 2 , Minakshi Das 3 , Dr. Mimi Das Saikia 4 1,2,3 B.tech students, Civil Engineering, Assam down town University, Guwahati, Assam, India 4 Professor, Civil Engineering, Assam down town University, Guwahati, Assam, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - The aim of the study is to represent the water quality of Deepor Beel in terms of Water Quality Index (WQI) parameters and to assess the contamination sources. For determining the water quality variation, data were collected in the month of September and October, 2017 from 6 different sampling stations distributed around the Beel. The 13 Physico- chemical water quality indicators used are - Temperature, pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solids (TSS), Hardness, Alkalinity, Conductivity, Calcium, Magnesium, Chloride and Turbidity. The WQI calculation was done using arithmetic index method. The WQI value for these samples ranges from. The calculation was done using arithmetic index method. More or less, water of all the sites are found to be affected. The WQI value for these samples ranges from 78.82 to 158.25. The highest WQI value of 158.25 was recorded from site2 (Pamohi, near railway bridge) which is a picnic spot and its water is unsuitable for drinking and other house hold purposes. Deepor Beel is a large and internationally important natural wetland of Brahmaputra valley located in the Guwahati city. The waste from the city to this Beel has mainly degraded its water quality and hence it needs preventive study to take strong step for providing overall safety to the Beel. Key Words: Deepor Beel, Assam, Water Quality Index, Physico-Chemical Parameters, Weighted Arithmetic Index Method 1. INTRODUCTION Water quality describes the conditions of the water, including chemical, physical, and biological characteristics, usually with respect to its suitability for a particular purpose. The composition of water is affected by natural processes and human activities and is controlled by dissolved as well as suspended constituents. Other important factors affecting water quality include intensity and composition of the rainwater and the runoff , chemical interactions between water and soil composition or sediment, use of fertilizers or some chemicals in agricultural practices, industrial activities in the catchment and effluent discharge , emissions and subsequent depositions from the atmosphere and solid waste dumping. A healthy river or any wetland is very much essential as it is a source of fresh water for the substance and well-being of a society. But, unfortunately these natural resources are continuously being used during the last few decades for the society development and flood hazard mitigation. However, the Brahmaputra river along with their numerous wetlands in North-East India serve as the refuge to diverse organism and sub-ecosystems. Water Pollution is the contamination of water bodies such as lakes, rivers, oceans, aquifers and groundwater. This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds. Despite its importance to human life, water is the most poorly managed resources in the world. The existing tendency of industrialization and urbanization may contribute greatly to the poor quality of water through indiscriminate disposal of solid waste, industrial effluents and other toxic wastes which are the major environmental issues causing threats to the existence of human being. Wetlands are among the most productive ecosystem in the world and are associated with the environmental, social, and economic well-being of society. They provide livelihood & nutrition to the local human population. Wetlands near towns and cities have been adversely affected by urban storm water runoff. . There are no regulations controlling inputs from non-point sources because of difficulty in implementing them and the wetlands have continued to receive large loads of pollutants. The pollutants from city streets, urban and suburban households, business and industrial establishment are carried into low lying wetlands nearby, deteriorating water quality and destroying fish habitats and killing aquatic life including water birds. One of the largest & most important riverine wetland in the Brahmaputra Valley of lower Assam is the Deepor as it has a great biological and environmental importance. But the inflow wastewater from Guwahati city to this Beel has degraded its water quality making it hazardous. It is the only major storage water basin for Guwahati’s drainage. Thus, for the importance of freshwater body towards society its water quality assessment in terms of water quality index (WQI) is required to be found out. It will give an overall picture of the current water quality status of the Beel. 2. LITERATURE REVIEW Barman D et al., (2015) in this paper, eleven physico – chemical parameters of wetlands in Meghalaya were recorded in different seasons for two years to assess the quality status of water. COD and TSS were beyond the permissible limit. It may be due to addition of sewage or other agricultural residues. Brraich Singh Onkar et al.,(2015) Studied physico-chemical parameters of Ranjit Sagar Wetland, Punjab and found that WQI indicated poor quality of water so water of this wetland is not suitable for drinking