Journal of Global Resources
doi.org/10.46587/JGR.2020.v06i02.001

Volume 6 (02)
July 2020
Page 01-09
ISSN: 2395-3160 (Print), 2455-2445 (Online)

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ASSESSING GROUNDWATER QUALITY USING GEOSPATIAL TECHNOLOGY: A CASESTUDY OF SURAT DISTRICT, GUJARAT, INDIA
Mukesh Kumar Bind1 and Rolee Kanchan2
1
Research Scholar, 1Professor
Department of Geography, The Maharaja Sayajirao University of Baroda, Vadodara, India
Email: roleekanchan@gmail.com, bnmukesh1994@gmail.com
Abstract: The quality of water is a vital concern for mankind since it is directly linked to humanhealth. Groundwater is a pivot because of its multiple uses for example, drinking, irrigation, andindustrial, etc. Thus, the availability of water and also its quality are the dimensions essential for
research. It has become necessary to determine the Groundwater Quality and for its
determination, Water Quality Index (WQI) is an important index and Geospatial Technology isan effective tool. Hence, the present study was performed to determine the level of somephysical and chemical properties of water in pre and post-monsoon seasons (2017-18) in Surat
district, Gujarat, India. The objective of the paper is to assess the spatial pattern of groundwater
quality with the use of Geospatial technology (GIS).Water quality was assessed using pH,
turbidity, Total Dissolved Solid (TDS), calcium, magnesium, sulphate, chloride, fluoride, nitrate,
alkalinity and total hardness parameters. Water Quality Index (WQI) is calculated to determine
the quality of groundwater. The water quality index category of<25 WQI was noted in 20.44
percent area during pre-monsoon which decreased to 18.36 percent in post-monsoon. 72.66
percent area had 25-50 WQI. After the rains, this area decreased to 62.28 percent. <25 WQI
was noted in 22.99 percent samples in pre-monsoon which reduced to 19.41 percent in the
post-monsoon. The next category with 25-50 WQI was noted in 67.20 percent samples in premonsoon and 56.87 percent in the post-monsoon season. 50-75 WQI was noted in 9.80 percent
samples in pre-monsoon which increased to 20.44 percent in the post-monsoon season. The
range with 75-100 WQI was not detected in any of the samples in pre-monsoon and wasobserved in 3.26 percent samples after the rains.
Key words: Spatial pattern, Water Quality Index, Variation Analysis, IDW, GIS.
Introduction
Groundwater is a prime natural resource and because of its multiple uses, it is considered to be
an important component. The quality of groundwater depends upon many natural conditions like
local climate, amount and intensity of rainfall, sub surface slope, geology, grain size of soil etc.
The hydrochemistry of groundwater determines its quality and subsequently its utilization. Oneof the threats to groundwater quality is the rapid increase in urbanization and industrialization
which might lead to its deterioration and become less suitable for drinking, irrigation, agriculturaland industrial purposes. Eleven parameters considered for the present study are pH, turbidity,
Total Dissolved Solid (TDS), calcium, magnesium, sulphate, chloride, fluoride, nitrate, alkalinity,
and total hardness. Groundwater quality can be influenced directly and indirectly by
microbiological processes which can transform both inorganic and organic constituents ofgroundwater through geochemical processes (Chapelle, 1993).Groundwater pollution occurs
when used water is returned to the hydrological cycle (Basavarajappa and Manjunatha, 2015).
Groundwater bodies are always less accessible than surface water bodies and technicallydifficult to derive a real picture. It contaminates mainly due to the rapid increase in population,industrialization, mining operations, application of fertilizers in agricultural fields and othermanmade activities (Rao et al., 2012). Industrialization is one of the most important phenomena
which ignites the mechanism of development. Disposal of solid waste in open pits anddepression, discharge of untreated liquid waste through open drains, and emission of toxic
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gases into the atmosphere are a few common features prevalent in the industrial region and its
vicinity. Groundwater gets contaminated in various ways such as excessive use of fertilizer infarming, seepage from effluent bearing discharged from industries, or human intervention. Oncethe groundwater gets contaminated, its quality cannot be restored by stopping the pollutant fromthe source in a short period (Sadashivaiah, 2008). The occurrence, distribution and movement
and composition of groundwater are intricately linked to the structure and nature of thegeological formations (Freeze & Cherry, 1979). The distribution of water in terms of quality andquantity varies from place to place and from one geological formation to another (Fetter, 1994).
Surat District is one of the fast industrializing regions of the State which has manyindustrial zones like Hazira in the west, Olpad in north-west and Surat city itself. These
industries manufacture different types of chemicals, petrochemicals, polymers, fibres, etc.
(GSIDS, 2016). The physico-chemical parameters study could help to determine the water
quality. WQI calculation and Geographic Information System (GIS) has emerged as a powerfultool for storing, analysing and displaying spatial data and these data for decision making inseveral fields including environment, earth and engineering sciences, urban planning,
agriculture, water resources etc. GIS is used as an effective tool for solution for water resources
problem for assessing and mapping of groundwater quality. Thus, the present study is an
important step towards it.
Objectives
Keeping in view the importance of quality of water the objective of the present paper is: To assess the groundwater quality.
 Analyze the spatio-temporal variation
Methodology
The secondary data of all physico-chemical parameters were collected from Gujarat Water
Supply and Sewerage Board (GWSSB), Jal Bhavan, Surat. The temporal data of pre-monsoon
and post-monsoon 2017-18 was taken into consideration. 582 groundwater samples werecollected from wells, bores, and hand pumps spread over the Surat district. Eleven parameters
have been considered for calculation of WQI such as: pH, turbidity, Total Dissolved Solid (TDS),
calcium, magnesium, sulphate, chloride, fluoride, nitrate, alkalinity and total hardness for thewater quality calculated by using Horton’s method (1965) in original form, latter which modified
by Brown et al., 1972 to determine the single value called Water Quality Index. WQI was
inputted into ArcGIS 10.2 and Spatial Interpolation Method was applied and in this paper IDW(Inverse Distance Weighting) method was applied for the spatial pattern. For calculation of
Water Quality Index, MS Excel 2013 was used and diagrams were prepared in Origin Pro
9.1.ArcGIS10.2 was used for the representation of the map.
Spatial Interpolation Method
Interpolation method is the process of using point with known value or sample point to estimate
at other unknown point. It can be used to predict unknown value for any geographic point data.
In this paper IDW (Inverse Distance Weighting) method was applied for spatial pattern of thestudy area. This method gave a better visual illustration to understand the present conditions
each of the parameters (Ghosh and Kanchan, 2014). The IDW interpolator assumes that each
input point has a local influence that diminishes with distance. It weights the point closer to theprocessing cell greater than those further away. A specific number of point or all points within a
specific radius can be used to determine the output value of each location.

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Figure 01: Ground Water Sample Location

Water Quality Index
Water Quality Index (WQI) provides information about water quality in a single value. It is
commonly used for the detection and evaluation of water pollution and may be defined as areflection of the composite influence of different quality parameters on the overall quality ofwater (Horton, 1965). WQI indices are broadly classified into physico-chemical and biologicalindices. The former are based on the values of various physical and chemical parameters inwater samples while biological indices are derived from biological information. Here, an attempt
has been made to calculate the water quality index of the Surat district based on physicochemical data. This research has adopted Horton’s Method (1965) in its original form.
𝑾𝑸𝑰 =∑𝒒𝒏 . 𝑾𝒏
∑𝑾𝒏

Where,𝒒𝒏 = Quality rating of nth water quality parameter, 𝑾𝒏 = Unit weight of nth water quality
parameter.
Quality rating (𝒒𝒏)
The quality rating (𝒒𝒏) is calculated using the expression given in Equation:
𝒒𝒏 = [(𝑽𝒏 − 𝑽𝒊𝒅 )] × 𝟏𝟎𝟎(𝑺𝒏 − 𝑽𝒊𝒅 )Where, 𝑽𝒏= Estimated value of nth water quality parameter at a given sample location.
𝑽𝒊𝒅 = Ideal value for nth parameter in pure water. (𝑽𝒊𝒅 For pH = 7 and 0 for all other parameters).
𝑺𝒏 = Standard permissible value of nth water quality parameter.
Unit weight (𝑾𝒏 )The unit weight (𝑾𝒏 ) is calculated using the expression given in Equation:
𝒌
𝑾𝒏 =
𝑺𝒏
Where,𝑺𝒏 = Standard permissible value of nth water quality parameter. 𝒌= Constant of proportionality
and it is calculated by using theExpression given in Equation
𝐤=

3

𝟏
∑

𝟏
𝐒𝐧=𝟏,𝟐,…𝐧

WQI and Status
Table 01: Ranges of WQI and Status and their Possible Uses as Per Horton’s Method
Sr. No
WQI
1
0-25
2
25-50
3
50-75
4
75-100Source: Horton’s Method (1965)

StatusExcellent
Good
Fair
Poor

Possible usages
Drinking, Irrigation, and Industrial
Domestic, Irrigation and Industrial
Irrigation and Industrial
Irrigation

Standard values and unit weights of water quality for Physico-chemical parameters
Table 02: Standard Values of Water Quality Parameters and their Corresponding Ideal Values andUnit Weights
Name of
Permissible
Vid=(1/sn)
K=[1/({1/Sn=1,2,n)]Parameters
Standards
Ph
8.5
0.118
0.9700
TDS
2000
0.001
0.9700Turbidity
50.200
0.9700T_hardness
600
0.002
0.9700
Calcium
200
0.005
0.9700Mg
100
0.010
0.9700Chloride
1000
0.001
0.9700Sulphate
200
0.005
0.9700
Nitrate45
0.022
0.9700
Fluoride
1.5
0.667
0.9700
Alkalinity
600
0.002
0.9700Source: Bureau of Indian Standards, GOI

Unit weight (k/Sn)
0.11410.00050.19400.00160.00490.00970.00100.00490.0216
0.64670.0016

Figure 02: Flow Chart showing the Methodology
Physico-Chemical Parameters

Calculation of Water Quality Index

ArcGIS10.2

Spatial Interpolation Method

Inverse Distance Weighted Applied

Spatial Pattern of Ground Water Quality

Study Area
Surat district lies between 20°30: 21°30'N and 72°35: 75°20'E with a total geographical area of
4,378 sq. km. (District Census Handbook Surat 2011). River Tapi is a major river that flows
downstream towards the Gulf of Cambay. This district has many industrial zones like Hazira in
the west, Olpad in north-west and Surat city. These industries manufacture different types ofchemicals, petrochemicals, polymers, fibres, etc. (GSIDS, 2016).
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Figure 03: Location Map

Geomorphology
Geographically, the district lies on the western coastal land of the Deccan peninsula. The
distinct zones viz. hilly area is dominant in the north-eastern part, piedmont slope in east-central
and this part shows a gentle slope towards the west. The topography is mainly plain withmoderate to the deep cutting river valley and occasional hillocks. The alluvial plain is situated in
the central part of the district and is characterized by flood plains of Tapi, Kim, and Purna
Rivers. The coastal plain towards west merges into dry barren sandy shorelines (CGWB 2013).
Figure 04: Geological Map, Surat District

Geology
The geological formation of the district falls under the Deccan trap (Basalt rock), flood plain.
Hydrogeology
The hydro-geological framework of the area is essentially governed by geological setting, Tapi
River, distribution of rainfall fall and facilities of circulation and movement of water through5interconnected primary and secondary porosity of the geological units forming the aquifers. The
major aquifers in the district are formed by alluvium and Deccan trap basalt. The alluvium
occurs in the western part of the district and along the streams whereas in eastern parts
weathered and fractured basalt from aquifers.
RESULTS AND DISCUSSIONWQI of Pre-monsoon Groundwater Quality
The water quality of <25 was noted in 22.99 percent samples and it was largely observed in thenorth-eastern part of the study area. Small pockets were seen in north-western and as small
patches in the south of the study area. This range of water quality is excellent for drinking.
Figure 05: Ground Water Quality, Surat District, 2017-18

Figure 5This range was dominatingly observed in the north-eastern part. This area has a Deccan
trap where the rocks of very hard (igneous rock {basalt rock} with dykes). Chances of infiltrationof water, reduces in hard rock largely due to porosity. Another large area is observed in thewestern part of the district. This area is an alluvial plain (sand and clay deposition) at the mouthof the Tapi River. The continuous flow affects the quality of the groundwater. It is continuously
recharged by freshwater. WQI between 25 to 50 was noted in 67.20 percent samples spreadingover 72.66 percent area. This range covered the entire region and is considered good for
drinking, irrigation and industries. This area is both an alluvial plain as well as Deccan trap. The
western part falls under the hilly region and the eastern part is plain. According to CGWB thegroundwater flows from west to east directly in direction with the terrain. The range between 50
to 75 WQI is noted in 9.80 percent samples and is spread 6.88 percent area. This range waslargely observed in the northern segment of the study area. The small isolated pockets werealso noted in the western and southern half of the district. This range of water quality is fair andit’s possible usage only for irrigation and industrial purposes (according to BIS for irrigation).
The areas of northern pockets are nearer to industrial regions as well as Surat city (GSIDS,
2016). Another isolated pocket is observed in western side where water quality is not good, maybe (i) because of the nearness to industrial region of Hazira (GSIDS, 2016), (ii) slope of the landand deposition of sediments brought by Tapi river (CGWB, 2013), and (iii) it's an alluvial region(sand and clay deposits) which helps water to get mixed with groundwater because of the large
amount of porosity. No area is observed with >75 WQI.
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WQI of Post-monsoon Groundwater Quality
A change in water quality was observed between the two seasons because of rainfall. <25 WQI
was noted in 19.41 percent samples which were spread over 18.36 percent area dominatingly
in north-eastern, central-east, and as small isolated pockets in the western half. The geology ofthe eastern part plays an important role in this segment which predominantly has basalt rock
(Figure 4) and at the same time there is an absence of industries (GSIDS, 2016). Another area
where the water quality was excellent was on the western side. The downstream flow of theTapi River from east to west helps to maintain the groundwater quality (CGWB, 2016). The next
category (25 to 50 WQI) was noted in 56.87 percent samples covering 62.28 percent area. This
category was spread over the entire study area and this quality of water is permissible fordomestic, drinking, irrigation and industrial purposes. This range was absent in the northeastern part. Between 50 to 75 WQI was noted in 20.34 percent samples covering 16.30
percent area. It was observed largely in northern and southern half and as small isolated
pockets over the entire region except for in the north-east. >75 WQI was in 3.26 percent
samples and they covered 3.04 percent area. It was observed in a large area in the north-west
and as small isolated pockets in the southern half. This range of the WQI category is poor andcan only be used for irrigation. In this area water quality is not good because of the tidal flat andnearness of industries.
Analysis of Spatio-temporal Variation
WQI (Area): The water quality index category of<25 WQI was noted 20.44 percent area during
pre-monsoon which decreased to 18.36 percent in post-monsoon. As compared to premonsoon, 2.08 percent area has reduced in post-monsoon. The range of water quality is
excellent for all purposes viz. drinking, domestic, irrigation and industries. In pre-monsoon,
72.66 percent area had 25-50 WQI. After the rains, this area percentage decreased to 62.28
percent with a decrease of 10.37 percent. The next category with 50-75 WQI was noted in 6.30
percent area in pre-monsoon and 16.30 percent in post-monsoon depicting an increase of 9.42
percent in area. In another category with >75 WQI, which is not acceptable for drinking andirrigation purposes, no area was noted in pre-monsoon and 3.04 percent in the post-monsoon
season.
Figure 06: Water Quality Index (Area)

Water Quality Index (Area)
80
percent of Area

60
40

Pre-Monsoon
Post-Monsoon

20
0
0-25

25-50

50-75

75-100Ranges of WQIWQI (Samples): <25 WQI was noted in 22.99 percent samples in pre-monsoon which reduced
to 19.41 percent in the post-monsoon. As compared to pre-monsoon, 3.57 percent of samples
had reduced after the rains. The next category with 25-50 WQI was noted in 67.20 percent
samples in pre-monsoon and 56.87 percent samples in post-monsoon.10.37 percent of thesamples were less in the post-monsoon season. 50-75 WQI was noted in 9.80 percent samples
in pre-monsoon which increased to 20.44 percent in the post-monsoon season.

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The range with 75-100 WQI was not detected in any of the samples in pre-monsoon andwas observed in 3.26 percent samples after the rains. It was noted that in the lower WQI ofwater and dilution of different parameters is the probable reason for it. The percentage ofsamples decreased while this percentage increased after the rains. The infiltration besides, this
district has a major river Tapi and minor rivers and their tributaries in which the flow of water
increases and rate of infiltration also rises resulting into this pattern.
Figure 07: Water Quality Index (Samples)

percent of Samples

Water Quality Index (Samples)
80
70
60
50
40
30
20
10
0

Pre-Monsoon
Post-Monsoon

0-25

25-50

50-75

75-100Ranges of WQI

Conclusion
The present study focused on the spatial pattern of groundwater quality in Surat District,
Gujarat. Fluctuation was observed in each category of WQI in both seasons. The geologicalstructure, urbanization and use of fertilizer in the agricultural field played a significant role inaffecting water quality in the western part of the study area which is highly developed ascompared to eastern part. It is very essential to sustain groundwater quality in poor quality
zones in the district. For the improvement in groundwater quality, construction of concretedrainage lines, treating of industrial pollutant water before discharging into river, continuous
monitoring of water quality, reframing the use of fertilizer limit for agricultural practices andreframing policy for discharging of industrial effluents are some of the means for improvising thewater quality. In the overall study, the eastern part of the study area has good water quality
which is suitable all purpose (viz. drinking, domestic, irrigation as well as industrial) because
their geological structure is made up of basalt rock which helped in purifying water, absence ofindustries specifically chemical and urbanization This part is largely covered by forest and water
bodies (UkaiDam).
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