International Journal of Civil, Structural, Environmental and Infrastructure Engineering Research and Development (IJCSEIERD) ISSN 2249-6866 Vol. 3, Issue 2, Jun 2013, 135-144 © TJPRC Pvt. Ltd. ASSESSMENT OF SPATIAL DISTRIBUTION OF GROUNDWATER QUALITY IN KONDAGATTU CATCHMENT OF GREATER VISAKHAPATNAM MUNICIPAL CORPORATION, INDIA – A GIS BASED APPROACH JANARDHANA SWAMY C1, VENKATESWARA RAO T2 & PRADEEP KUMAR G. N3 1Research Scholar, Department of Civil Engineering, College of Engineering, Sri Venkateswara University, Tirupati, Andhra Pradesh, India 2Scholar, Department of Geo-Engineering, College of Engineering, Andhra University, Visakhapatnam, Andhra Pradesh, India 3Professor, Department of Civil Engineering, College of Engineering, Sri Venkateswara University, Tirupati, Andhra Pradesh, India ABSTRACT Qualitative analysis of groundwater is having equal importance on par with the quantitative assessment for best water management practice. Present study appraises the groundwater quality in Kondagattu Catchment of Greater Visakhapatnam Municipal Corporation. Groundwater Quality Index (GWQI), a congregate parameter representing the quality and suitability of groundwater is computed and coupled with GIS technology. Spatial analyst module in ArcGIS software has been used to generate the spatial distribution of water quality parameters. Based on the analysis, most of the area under study falls in good water zone. The results revealed that the spatial distribution maps generated for various physico•chemical parameters using GIS techniques could be useful for planners and decision makers for initiating groundwater quality development. KEYWORDS: Spatial Distribution, Groundwater Quality Index (GWQI), Greater Visakhapatnam Municipal Corporation, Geographical Information System (GIS) INTRODUCTION GENERAL Groundwater, of late has become an important source of water to reckon with to meet different needs of an individual and also society. Heavy and indiscriminate usage of this source obviously results in degradation of its quality. Ascertaining the quality is crucial before its use for various purposes such as drinking, agricultural, recreational and industrial use. Water Quality Index (WQI) is an important parameter for ascertaining water quality and its suitability for use. It is one of the most comprehensive tools to yield information on the quality of water. It is simply an integration of data on complex quality parameters and generating a score that describes water quality status. It is also defined as a rating that provides the composite influence of quality parameters. Brown et al. (1972) developed a water quality index paying great rigor in selecting parameters, developing a common scale, and assigning weights for which elaborate Delphic exercises were performed. This effort was supported by the National Sanitation Foundation (NSF) and that is why also referred as NSFWQI. This work seems to be the most comprehensive and has been discussed in various papers (Brown et al, 1972; Landwehr and Deininger, 1976). 136 Janardhana Swamy C, Venkateswara Rao T & Pradeep Kumar G. N Swarna Latha et al. (2010) used raster interpolation technique in GIS is used to delineate the distribution of various water quality parameters. Along with raster interpolation technique, point layer data of sampling location were imported duly assigning unique codes and standard permissible and excessive values of various water quality parameters in the study area resulted in delineation of spatial distribution maps of water quality parameters and groundwater quality index (GWQI). STUDY AREA Greater Visakhapatnam Municipal Corporation (GVMC) is the second biggest city with rapid urbanization in the State of Andhra Pradesh. Visakhapatnam or Vizag is located midway between two metropolitan cities of India namely Kolkata and Chennai. The city consists of golden beaches, green fields, hills consisting of valleys with peaceful living conditions, great history and varied environment. The Greater Visakhapatnam, lies between 17º 32' N to 17º 51' N latitudes and 83º 05' E to 83º 24' E longitudes with semi arid maritime tropical climate situated in coastal Andhra Pradesh on the east coast of India. Figure 1: Map Showing the Study Area The study area is located adjacent to the Meghadri Gadda watershed bounded between latitudes 17043'30" to 17049'00" and from longitudes 83011'45" to 83016'30". Kondagattu Catchment area is starting from Visakhapatnam Air Port and is ending at Pendurthi covering famous Hindu pilgrimage of Simhachalam Hills. The temperature exhibits extreme characteristics, decreases due to South West Monsoon and tumbles to a mean minimum of 18o C by December and then gradually increases to mean maximum temperature of 40o C by the end of May. The study area receives annual normal rainfall between 1028 to 1111 mm, the maximum received is from south-west monsoon season from August to October. The relative humidity averages 72% over the year with 64% of lowest average occurs in November and December and 77% of highest average occurs in April and May. The maximum altitude is 478 m., on top of Simhachalam Assessment of Spatial Distribution of Groundwater Quality in Kondagattu Catchment 137 of Greater Visakhapatnam Municipal Corporation, India – A GIS Based Approach hill and the minimum elevation is about 10 m. observed in the southern part of the study area at Kothapalem. The study area is as shown in figure 1. MATERIALS AND METHODS Groundwater Sampling and Analysis Water samples were collected in November’ 2012 from 73 wells spread over 20 suburbs of the study area. Plastic containers were used for the collection of water samples and analyses were carried for water quality parameters viz. pH, Total Dissolved Solids (TDS), Alkalinity (Al), Chlorides (Cl), Fluorides (F), Nitrate (No3), Sulphate (So4), Calcium (Ca), Magnesium (Mg), Total Hardness (TH) and Electrical Conductivity (Ec) in the laboratory. Global Positioning System (GPS) was used for locating sampling stations. As per APHA (1995) , methods adopted for estimating various groundwater parameters are detailed in Table 1. Table 1: Methods Adopted for Estimating Different Physico-Chemical Parameters of Groundwater in the Study Area Sl. No. Parameters Method 1 pH Digital pH meter 2 Total Dissolved Solids (TDS) Elico meter 3 Alkalinity (Al) Titrimetry 4 Chlorides (Cl) Titrimetry 5 Fluorides (F) Spectrophotometric method 6 Nitrate (No3) Spectrophotometric method 7 Sulphate (So4) Spectrophotometric method 8 Calcium (Ca) Titrimetry 9 Magnesium (Mg) ICP Mass Spectrometry 10 Total Hardness (TH) EDTA titration method 11 Electrical Conductivity (Ec) Elico meter Water Quality Index (WQI) Numerical representation of overall quality of water is Water Quality Index, which is proven to be a very useful tool in water quality management. Horton (1965) defined Water Quality Index as a reflection of composite influence of individual quality characteristics on the overall quality of water. It is an effective tool to bring several water quality parameters onto a common scale and forming into a unique number with a chosen method of estimation. WQI value greatly varies with quality parameters selected. In the present study, eleven physico-chemical parameters namely pH, Total Dissolved Solids (TDS), Alkalinity, Chloride, Fluoride, Nitrate, Sulphate, Calcium, Magnesium, Total Hardness and Electrical Conductivity were used to calculate WQI. Estimation of Water Quality Index (WQI) A widely used method of computing WQI, developed by Brown et al. (1972) and supported by the National Sanitation Foundation (NSF) is used in the present study to compute WQI. Each of the 11 parameters has been assigned a weight (wi) based on its influence on health hazards. A maximum weight of 5 has been assigned to parameters like chloride, magnesium and electrical conductivity. A minimum weight of 1 is given to calcium. Other parameters were assigned a weight between 1 and 5 as listed in Table 2. 138 Janardhana Swamy C, Venkateswara Rao T & Pradeep Kumar G. N Relative weight (Wi) of each parameter is computed using Equation (1): Wi = wi / ( ∑ wi ) (1) where wi = weightage of individual parameter, ∑ wi = sum of all the weightages. Then quality rating is computed using Equation (2) qi= ( ci / si ) *100 (2) where, qi = the quality rating, ci = concentration of each chemical parameter in each water sample in mg/l and si = allowable water quality standard for each chemical parameter in mg/l (Table. 2). Table 2: The Weight, the Calculated Related Weight Values and Water Quality Standards as Per BIS & WHO BIS & WHO Relative Weight Sl. No Chemical Parameters Standards Weight (wi) Max. Limit (Si) (Wi) 1 pH 8.50 2 0.0526 2 Total Dissolved solids (mg/l) 2000.00 3 0.0789 3 Alkalinity (mg/l) 600.00 4 0.1053 4 Chlorides (mg/l) 1000.00 5 0.1316 5 Flouride (mg/l) 1.50 2 0.0526 6 Nitrate (mg/l) 45.00 5 0.1316 7 Sulphate (mg/l) 400.00 4 0.1053 8 Calcium (mg/l) 200.00 1 0.0263 9 Magnesium (mg/l) 30.00 5 0.1316 10 Total Hardness (mg/l) 600.00 2 0.0526 11 Electrical conductivity (µS/cm) 3000.00 5 0.1316 ∑w 38 i Weighted quality rating, Sii, is then determined for each parameter using Equation (3). Sii = Wi * qi (3) qi = rating based on concentration of ith parameter. Groundwater Quality Index (WQI) is then arrived at using Equation (4): n GWQI = Sii (4) 1 n = number of parameters. Computed WQI values are then classified into five categories as excellent, good, poor, very poor and unfit for drinking as shown in Table. 3. Table 3: Classification of Groundwater Based on GWQI