! "" # $# %$& ’() Determining Water Quality Index for the Evaluation of Water Quality of River Godavari Er. Srikanth Satish Kumar Darapu, Er. B. Sudhakar, Dr. K. Siva Rama Krishna, Dr. P. Vasudeva Rao 1 Dr. M. Chandra Sekhar 2 ! " #$% %&# ’(’ ) * +, - ./ 0/, ( 1 0/, )/! ( 2,3, ’(’ ) * + # , -. " ## / 0. # "" ! ! / 0. - !# ## " . / / #1 #. . # # " ! !# / # #.2 " -# #. 3. # "- 4 " - #0 / ! $ + 5. , %+5& " # .# " " - " 0. ! " / -. 3 # ## / -# # -# / ! / 0. # 3 # -" " -/ / 0. " " 3 # . ! 6 . #" ! +5 ! ! #!# ! 7"1 +"" #!!# ! / 0. %8 & ##" # # ! 3 !/ .9 . !!# / 0. "!#. 3 /"" #!!# # # " 3 ! +5 " 3 +5 ! . ! "8 %! "& 9 3 . # . # /# - ! !"#— + 5. , 6 ! + 5. +5 " +5 " , +"" !!# !# " ! + 5. %+5& . :0#. :# # , $" . +5 # I. INTRODUCTION $% & ’ ’ (# &#() ’ *& && ’ & ( ’ & + ( & (#, – Luna Leopold (1915-2006), U.S. geomorphologist and hydrologist Water Quality is an important factor to judge environment changes, which are strongly associated with social and economic development. The evaluation of water in the developing countries has become a critical issue in recent years, especially due to the concern that fresh water will be scarce in near future. Water form a certain source may be good enough for drinking without any treatment but it may not be suitable as a coolant in an industry. It may be good for irrigating certain crops but not for certain other crops. Expressing water quality is not as easy as expressing water quantity. One rudimentary way to describe the quality of water is to list out the concentrations of constituents which may range from 20-odd common ones to a few hundreds. Comparing the quality of water sources cannot be done easily by comparing the list of constituents of samples. For e.g. a water sample containing six components in 5% higher-than- permissible levels: p H , hardness, chloride, sulphate, iron and sodium may not be as bad for drinking as another sample with just one constituent – mercury – at 5% higher-than- permissible. It is necessary to point out that the current conditions in the manual processing to a large number of analytical data practically prevent faster interpretation of results. As a solution, Water Quality Indices aim at giving a ‘single value’ to the water quality of a source on the basis of one or other system which translates the list of constituents and their concentrations present in a sample/samples into a single value. ’ , 4 5 ,6 +45- Water Quality Index is a form of average derived by relating a group of variables to a common scale and combining them into a single number. A WQI summarizes information by combining several sub-indices of constituents (quality variables) into a 6. The group should contain the most significant parameters of the dataset, so that the index can describe the overall position and reflect change in a representative manner. Water resource professionals generally communicate water quality status and trends in terms of the evaluation of individual water quality variables. While this is readily understood within the water resources community, it does not readily get translated to communities having profound influence on water resources and related policies: the