1
INTRODUCTION:
Groundwater
is one of earth’s most vital renewable and widely distributed resources as well
as an important source of water supply throughout the world. The quality of
water is a vital concern for mankind since it is directly linked with human
welfare. In India, most of the population is dependent on groundwater as the
only source of drinking water supply. The groundwater is believed to be
comparatively much clean and free from pollution than surface water. Groundwater
can become contaminated naturally or because of numerous types of human
activities; residential, municipal, commercial, industrial, and agricultural
activities can all affect groundwater quality.
Water is the basic requirements of all
life on Earth. The origin of life has
been attributed is water along with other basic elements water the source of
life is passionate. It must be remembered that any natural or manmade activity
on the surface of the earth will have its for most impact on the quality and
quantity of water this will be taken into the biosphere systems and ultimately
lead to hydrological extremes.
water quality refers to the chemical,
physical and biological characteristics of water Another general perception of
water quality is that of a simple property that tells whether water is polluted
or not. It is a measure of the condition of water relative to the requirements
of one or more biotic species and or to any human need or purpose. The most
common standards used to assesswater quality relate to health of ecosystems,
safety of human health and drinking water. In fact, water quality is a complex
subject, in part because water is a complex medium .The increase in population
and urbanization and urbanization necessitates growth in the agricultural and
industrial sectors which demand for more fresh water. When surface water is the non-available mode
the alternative is to depend on ground water.
The dependability on ground water has
reached an all time high in recent decades due to reasons such as unreliable
supplies from surface water due to vagaries of monsoon, increase in demand for
domestic, agricultural and industrial purposes. This has resulted in over
exploitation all over the country and in certain places it has reached critical
levels like drying up of aquifers.
1.2 NEED FOR THE STUDY:
Now a days water scarcity increases
rapidly due to decrease of ground water.
The ground water is also polluted due to various artificial man-made
activities. Due to this, quality of the
water is reduced. This will produce
various adverse impacts on human beings, animals and plants.Therefore, it is
necessary to monitor the water quality.
1.3
OBJECTIVES:
objectives of the Groundwater quality
are as follows:
i.
To check whether the water quality is in compliance with the standards
and hence suitable or not for the designated use.
ii.
To monitor the efficiency of a system working for water quality
maintenance
iii.
To check whether up gradation /change of an existing system is
required and to decide what changes should take place.
iv.
To monitor whether water quality is in compliance with rules and
regulations.
v.
To create Water Quality Index
(WQI).
2
.LETRATURE REVIEW:
i.
P.
Balakrishnan. Abdul Saleem. and N. D. Mallikarjun.:
Spatial variations in ground water quality in
the corporation area of Gulbarga City located in the northern part of Karnataka
State, India, have been studied using geographic information system (GIS)
technique. GIS, a tool which is used for storing, analyzing and displaying
spatial data is also used for investigating ground water quality information.
For this study, water samples were collected from 76 of the bore wells and open
wells representing the entire corporation area. The water samples were analyzed
for physico-chemical parameters like TDS, TH, Cl- and NO3-, using standard
techniques in the laboratory and compared with the standards. The ground water
quality information maps of the entire study area have been prepared using GIS
spatial interpolation technique for all the above parameters. The results
obtained in this study and the spatial database established in GIS will be
helpful for monitoring and managing ground water pollution in the study area.
Mapping was coded for potable zones, in the absence of better alternate source
and non-potable zones in the study area, in terms of water quality.
ii.
T.
Subramani, S. Krishnan, P. K. Kumaresan:
Groundwater Consultants were retained by the
Resource Inventory Committee(RIC), Earth Science Task Force to review
groundwater quality. The study team have reviewed existing methods for the
acquisition, processing, and dissemination of groundwater and other jurisdictions. The results of this
review and assessment are presented in a two-volume report:
Volume
1: Review and Recommendations offers
suggestions to facilitate the collection, management, and dissemination of
groundwater information;
Volume
2:Criteria and Guidelines has been prepared to encourage a consistent approach
to groundwater quality.
This
project included surveying a broad group of individuals to obtain comments on
groundwater quality as well as holding a
stakeholder workshop which provided a forum for discussion on this important
issue.
3.
GROUND WATER:
3.1
Defination:
Ground water is the water present beneath Earth’s surface
in soil pore space and in the fractures of rock formation..Groundwater lies beneath the
surface of the earth ,but is affect by surface supply.Groundwater is affected
by changes to all of the earth sphere due to linkage through the hydrologic
cycle.Ground water fills the spaces
between soil particle and fractured rock beneath the earth surface.
3.2
Hydrologic Cycle: The term
hydrologic cycle is used to refer to the constant movement of water above, on,
and below the surface of the earth. The concept of the hydrologic cycle is
central to an understanding of the occurrence of water and the development,
management and protection of the ground water resource.
Although
the hydrologic cycle has neither a beginning or an end, it is convenient to
discuss its principal features by starting with evaporation from vegetation,
from exposed surfaces including the land surface, and from the ocean. This
moisture forms clouds which, under favourable conditions, returns the water to
the land surface or oceans in the form of precipitation.
Precipitation
occurs in several forms, including rain, snow, and hail, but we will consider
only rain in this discussion. The first rain wets vegetation and other surfaces
and then begins to infiltrate into the ground. Infiltration rates vary widely,
depending on land use, from possibly as much as 25 mm per hour in mature
forests to a few millimetres per hour in silty soils under cultivation. When
and if the rate of precipitation exceeds the rate of infiltration, overland
flow occurs.
The
first infiltration replaces soil moisture and thereafter the excess percolates
slowly downward to the zone of saturation. The water in the zone of saturation
moves downward and laterally to areas of ground water discharge such as springs
on hillsides or seeps in the bottom of streams and lakes or beneath the ocean.
Water
reaching streams, both by overland flow and from ground water discharge, moves
to the sea where it is again evaporated to perpetuate the cycle.
Fig 3.1:Hydrological Cycle
3.2.1.
Global water cycle:
Water covers about three-quarters of Earth's surface
and is a necessary element for life. During their constant cycling between
land, the oceans, and the atmosphere, water molecules pass repeatedly through
solid, liquid, and gaseous phases (ice, liquid water, and water vapor), but the
total supply remains fairly constant. A water molecule can travel to many parts
of the globe as it cycles.
.
Surface area (million km)
|
Volume area (million km)
|
Volume %
|
Equivalent depth
|
Residence time
|
|
Oceans and seas
|
361
|
1370
|
94
|
2500
|
4000 years
|
Lakes and reservoirs
|
1.55
|
0.13
|
<0.01
|
0.25
|
10 years
|
River channel
|
<0.1
|
<0.01
|
<0.01
|
0.003
|
2 weeks
|
Soil moisture
|
130
|
0.07
|
<0.01
|
0.13
|
2weeks to 50 years
|
Ground water
|
130
|
60
|
4
|
120
|
2weeks to 100000 years
|
Atmospheric water
|
504
|
0.01
|
<0.01
|
0.025
|
10 days
|
Table 1. Estimate of the world water balance
3.3 Ground Water Flow System:
ground
water system serves as both a reservoir and as a transmitting medium. Water
enters the ground water system in recharge areas and moves through them, as
dictated by hydraulic gradients and hydraulic conductivities, to discharge
areas.
The
pore structure of soils, sediment, and rock is a central influence on
groundwater movement. Hydrologists quantify this influence primarily in terms
of:
•
Porosity: the proportion of total volume that is occupied by voids, like the
spaces within a pile of marbles. Porosity is not a direct function of the size
of soil grains the porosity of a pile of basketballs is the same as a pile of
marbles. Porosity tends to be larger in well sorted sediments where the grain
sizes are uniform, and smaller in mixed soils where smaller grains fill the
voids between larger grains. Soils are less porous at deeper levels because the
weight of overlying soil packs grains closer together.
•
Permeability: ability of the soil to transmit water through it.Materials with
high porosity and high permeability, such as sand, gravel, sandstone, fractured
rock, and basalt, produce good aquifers. Low-permeable rocks and sediments that
impede groundwater flow include granite, shale, and clay
3.3.1:
Three Flavors of Rock:
1.Aquifer
Rock: An aquifer is an
underground layer of water-bearing permeable
rock, rock fractures
or unconsolidated materials (gravel, sand, or silt) from which groundwater can be
extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called
hydrogeology.
2.Aquitard
Rock: Aquitards separate aquifers and partially disconnect the flow of
water underground. Aquitards comprise layers of either clay or
non-porous rock with low hydraulic conductivity.
3:Aquiclude Rock:
An aquitard is a zone within the
earth that restricts the flow of groundwater from one aquifer to another. A
completely impermeable aquitard is called an aquiclude or aquifuge.
Figure 3.2 : Three flavor of rocks
4 .GROUND WATER QUALITY:
The quality of ground water in some parts of the country,
particularly shallow ground water, is changing as a result of human activities.
Ground water is less susceptible to bacterial pollution than surface water
because the soil and rocks through which ground water flows screen out most of
the bacteria. Bacteria, however, occasionally find their way into ground water,
sometimes in dangerously high concentrations. But freedom from bacterial
pollution alone does not mean that the water is fit to drink. Many unseen
dissolved mineral and organic constituents are present in ground water in
various concentrations. Most are harmless or even beneficial; though occurring
infrequently, others are harmful, and a few may be highly toxic.
and their levels in different locations of the study
area. The rapid growth of urban population in Gulbarga city led to unplanned
settlements where the access to sewerage is limited and pit latrines or septic
tanks are the only options available for sewage disposal. The main sources of
nitrate and other pollutants of urban groundwater is sewage and nitrate can
reach the aquifer by sewer leakage and, on-site disposal.
4.1 PARAMETER GROUND WATER
QUALITY:`
Various
chemical parameters like PH , TDS,
chloride temperature, turbidity and total hardness were analyzed in the
groundwater samples used for drinking purposes GIS is used to evaluate the quality of ground water.
The major ground water quality parameters such as,
1. pH 2. Total dissolved
solids 3. Sulphate 4. Chloride 5.Turbidity 6.. Temperature.
1. PH
pH is a measure of how acidic/basic
water is. The range goes from 0 - 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH
of greater than 7 indicates a base. pH is really a
measure of the relative amount of free hydrogen and hydroxyl ions in the water.
pH values ranged from 7.52 to 8.79 during pre-monsoon period
and 7.42 to 8.74 during post monsoon period. 56.25% of samples were above the
standard limit (6.5 to 8.5) prescribed by BIS.
2.Total Dissolved Solids
Dissolved solids" refer to any
minerals, salts, metals, cations or anions dissolved in water. Total dissolved solids (TDS) comprise inorganic salts (principally calcium, magnesium,
potassium, sodium, bicarbonates, chlorides, and sulfates) and some small
amounts of organic matter that are dissolved in water. The TDS values in the present study vary from 229 to 980 mg/l during
pre-monsoon and 221 to 973 mg/l in post-monsoon period. 42.5% of samples were
above the standard limit (500 mg/l) prescribed by BIS .
3. Turbidity:
Turbidity is the measure of the
relative clarity of water. Turbid water is caused by suspended and colloidal
matter and microscope organism.turbid water may result in soil erosion urban
runoff.
4.Chloride
In the present study, chlorides content
of underground water varied from 25 to 464 mg/l in pre-monsoon and 27.0 to
436.0 mg/l during post monsoon period. 30% of samples were found above the
standard limit (250 mg/l) prescribed by BIS. Chloride concentrations vary
widely in natural water and it directly related to mineral content of the
water. At concentration above 250 mg/l, water acquires salty taste which is
objectionable.Chloride is habitually
present in water in form of sodium chloride. Animals usually can drink water with much more
concentration than humans can tolerate (300 to 400 mg/L).
5. Total Hardness:
Total hardness is a measure of the
capacity of water to the concentration of calcium and magnesium in water and is
usually expressed as the equivalent of CaCo3 concentration. In the present study, the
total hardness of the water samples ranges between 212 and 598 mg/l during
pre-monsoon and 198 to 605 during post monsoon 98.8% of samples were found
above the standard limit (200 mg/l) prescribed by BIS. Hard water is useful in
the growth of children, if within the permissible limit.
Calcium and magnesium mostly cause the hardness of water.
The total hardness of water may be divided in to 2 types, carbonate or
temporary and bi-carbonate or permanent hardness. The
hardness produced by
the bi-carbonates of calcium and magnesium can be virtually removed by
boiling the water and is called temporary hardness. The hardness caused mainly
by the sulphates and chlorates of calcium and magnesium cannot be removed by
boiling and is called permanent hardness.
PARAMETER
|
STANDARD
|
WEIGHTAGE
|
PH
|
8.5
|
0.026742
|
TDS
|
500
|
0.00672
|
TURBIDITY
|
5
|
0.045461
|
CHLORIDE
|
250
|
0.000909
|
TOTAL HARDNESS
|
300
|
0.00758
|
TABLE:2
water quality parameter ,BIS Standard
,Weightage
4.2
Important Water Analysis Equipment:
i.
Total Organic
Carbon Analyzer
A
total organic carbon
analyzer determines the amount of carbon in a water sample. There are two types
of analyzers. One uses
combustion and the other chemical
oxidation.
Figure 3.3 : Total organic carbon analyzer equipment
ii.
pH
Analyzer
Water pH testers
and analyzers help analyze
pH levels and detect fault s in
systems with electronic pH meters.
Figure 3.4 : PH analyzer equipment
iii.
Water
Desalination Equipment:
The
parameters measured in Desalination instrument s include Alkalinity,(COD), Conductivity, Dissolved Oxygen ,Water
Hardness, Iron, Manganese, Turbidity in water etc.
Figure 3.5: water desalination equipment
iv.
electrical conductivity meter:-
An electrical
conductivity meter measures the electrical conductivity in a solution
. It is commonly used in freshwater systems to monitor the amount of nutrients, salts or
impurities in the water.
Figure 3.6: electrical conductivity
meter:
4.3
Ground Water Quality Index (WQI):
A Water Quality Index (WQI) is a means by which water quality data is summarized for
reporting to the public in a consistent manner. It is similar to the UV index
or an air quality index, and it tells us, in simple terms, what the quality of
drinking water is from a drinking water supply. The
objective of an index is
to turn complex water quality data into
information that is understandable and useable by the public.
WQI value
|
Rating of water
Quality
|
Grating
|
0-25
|
Excellent water quality
|
A
|
26-50
|
God water quality
|
B
|
51-75
|
Poor water quality
|
C
|
76-100
|
Very poor water quality
|
D
|
Above
|
Unsuitable for drinking purpose
|
E
|
Table 3 :Rating Of Water Quality Index
Determination Of Water Quality Index:
WQI is computed by adopting the
following formula The relative weight (Wi ) is computed
Wi= wi/
A quality rating scale (qi) for
each parameter is assigned:
qi = (Ci
/ Si) x 100
where
q= is the quality rating,
C = concentration of each
chemical parameter in each water sample in mg/L,
Si=Indian drinking water
standard for each chemical parameter in mg/ L
4.4 ADVANTAGE AND DISADVANTAGE OF GROUND WATER
QUALITY:
ADVANTAGE GROUND WATER QUALITY:
ADVANTAGE GROUND WATER QUALITY:
It is collected in its pure, natural form, which makes it
free of chemicals often found in city ordinance water.
It is also
free to the harvesters, reducing monthly costs with the elimination of a water
bill.
It is also sustainable and naturally soft due
to an absence of dissolved minerals and common urban contaminants
DISADVANTAGE OF
GROUND WATER QUALITY:
One distinct disadvantage to harvesting
ground water is the effort it takes to do so.
A
specific protocol must be followed to keep water safe, clean and convenient.
These include designating a catchment area to
collect the rain.
5 . CONCLUSION
The
analytical results shows higher concentration of hardness (98.8), iron (62.5%), pH (56.25),
calcium (43.8%) and TDS (42.5%) which indicates signs of water quality
deterioration as per BIS standards.
urgent
need for regular underground water quality monitoring to assess pollution
activity from time to time for taking appropriate measures in time to mitigate
the intensity of pollution activity.
The Rate at
which water infiltrates into the ground depends on the permeability of the
rocks and the state of the ground surface.
Reference:
1) Haran
,H., Evaluation of drinking water quality at Jalaripeta village of
Visakhapatanam district, Andra Pradesh
2)
Srivastao, D.P. Groundwater quality at tribal town; Nandurbar (Maharashtra).
Indian J. Environ. Ecoplan, 5(2): 475-479.
3)
GUPTA, S.G. Ground water pollution due to discharge of industrial effluents in
Venkatapuram area. Visakhapatanam, A.P. India. Environ.
4) Reddy, A.S, Vuppala P, MA (2007). Remote
sensing and GIS techniques for evaluation of groundwater quality in Municipal
Corporation of Hyderabad (Zone-V), India. Int. J. Environ. Res. Public Health.
5) Babiker,
IS, Mohamed AM, Hiyama T (2007). Assessing groundwater quality using GIS. Water
Resour. Manage.
6) Jain CK, Kumar CP, Sharma MK
(2003). Ground water qualities of Ghataprabha command Area, Karnataka. Indian
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