project studies - Artificial recharge and
Ground water irrigation
has gained importance during the last decade in Karnataka
through dugwells, dug-cum-borewells and borewells in some districts,
especially in areas where perennial rivers are absent.
Kolar is one among such districts
which has experienced high stage of ground water development where a
spurt in groundwater activity is seen during the past two decades.
The periodical monitoring of wells for the period 1973 to 1996
shows a declining trend in ground water levels.
The area showing declining trend in ground water levels are
associated with higher degree of ground water development.
Central ground water
Board under Central Sector scheme has carried out Experimental
Artificial Recharge Studies (EARS) in Gauribidanur and Mulbagal taluks
The main activities
carried out in the above taluks are:
Desilting of two tanks and converting the same
into Percolation tanks.
Watershed treatment in
Construction of point
recharge structures at 5 locations.
Gravity recharge wells at 2 locations.
Roof top rain water harvesting structure at Gauribidanur.
The existing defunct and silted up Minor Irrigation (M.I.) tanks at Errapothenahalli and Manchiganahalli were taken up for conversion to percolation tank after desilting. Government of Karnataka had plans to take up desilting of M.I. tanks in Kolar district on a large scale and in this context the district level authorities emphasized the need to quantify the additional recharge through such desilting programme. Keeping this in mind, it was planned to take up study of the tank bed seepage prior to desilting and after desilting and thereby quantifying the same.
Treatment of Basavapura
and Bhovibikkanahalli micro-watersheds with traditional water harvesting
structures to study the impact
the same on ground water recharge.
The studies were taken up as watershed development programme,
which are being taken up in Karnataka on a large scale and the present
study attempts to quantify the additional recharge by such programmes.
Check dams are the major structures constructed under this programme.
Five PRS were taken up
in the district. The
construction of PRS involves two stages of work.
Firstly, the construction of a borewell for recharge and
secondly, designing a filter bed around the recharge borewell.
The surface water either from the M.I. tank or from the nalla is
allowed into the filter bed. The
silt free water from the filter bed will be let into the recharge
borewell tapping fractured aquifer.
The drilling of recharge borewells together with observation
wells (ie: recharge well field) were taken up by CGWB.
The five well fields are located at Hosur (two nos.), Bhakthara
halli, Sonaganahalli and Manchiganahalli.
Gravity Recharge Wells:
Two gravity recharge
well fields were constructed, one each at Belchikkanahali and
Hussainpura. A short
duration injection test was conducted in these two well fields and
tested for their intake capacity rates.
The source water for the tests was transported through pipe line
from an existing irrigation borewell located about 700 meter away from
the well field.
Findings of Artificial
results carried out at Percolation tank beds prior to and after
desilting showed an improvement in tank bed percolation. The
infiltration rate ranged from 0.17 to 2.4 cm/hr prior to desilting
whereas the rate has increased in the range of 1.8 to 8.8 cm/hr after
desilting at Errapothenahalli. At
Manchiganahalli, it ranged from 1.2 to 5.8 cm/hr prior to desilting
whereas the same was observed to be in the range of 10 to 16.8 cm/hr
after desilting. The ground water level data during post desilting
periods reveals a built-up in storage in the order of 2 to 4.5 m to the
downstream of the tanks.
It has revealed that
the flow recorded is considerably reduced after the treatment and the
construction of the structures. A
built-up in storage was observed to be in the order of 3 to 5 m in the
phreatic zone. The treatment of Basavapura
microwatershed has shown watershed treatment can arrest flows
during monsoon and enhance recharge to ground water.
This indicates that watershed treatment especially in the drought
prone district of Karnataka can be taken up on a large scale
which can contribute greatly to recharging of ground water and
retention of moisture for crop production.
The recharge through
point recharge structure has benefited the deeper aquifer to build-up
storage locally and to improve the ground water potential and are
effective in recharging deeper aquifer and can be applied in feasible
areas of a drought prone district.
The total amount
sanctioned under the EARS is Rs. 44.116 lakhs and this amount has been
released to State Government by CGWB under the central sector scheme.
campus, Bangalore University.
0.026 MCM of freshwater
is discharged into Vrishabhavathi river, which is highly polluted. Two exploratory borewells drilled by CGWB under exploration
programme have turned out to be high yielding which cater to the needs
of University campus. A fall of 3 to 5 m in ground water level has been
observed during the last four years resulting in indiscriminate pumping
of the bore wells in the water shed. thus laying heavy stress on the
aquifer system. In view of this, studies have been taken up for
harvesting rainwater which goes as run off in the micro water shed of
the campus. In this context, the rainwater harvesting is proposed
through three check dams of which one is a combination structure
consisting of a subsurface dyke and check dam.
The scheme has been sanctioned during the year for an estimated cost of Rs.13.75 lakhs. Shri.Arjun Charan Sethi, Hon’ble Minister for Water Resources, Govt. India has launched the scheme during Feb.'2001 in presence of other dignitaries from Govt.of India, Govt.of Karnataka, Central Ground Water Board and Bangalore University. The construction of the recharge structures were completed.
c) Conjunctive Use Studies In Ghataprabha River Basin.
Conjunctive use study
of surface and ground water in
The study indicated that canal water utilisation in the left
A conjunctive use plan has been drawn both for left and
A total investment of Rs 40.5 crores has been suggested
An area about 50 sq.km
in and around Bhadravathi town in Shimoga district was
studied to assess the ground water quality and aquifer material
vis-a -vis the industries existing, agricultural
practices and urbanisation. The area is drained by the
perennial Bhadra River and the major industries are
M/s Mysore paper mill and M/s Visweshwariah Iron and Steel
The area falls
in southern transition agroclimatic zone and receives
a mean annual rainfall of 826.3 mm. Extensive irrigation from Bhadra
reservoir and Gondi channel, which are constructed across
the river Bhadra is practiced around Bhadravthi. Premonsoon survey was
carried out in June, 1994 during which 26 dug wells and
17 bore wells were identified for water level
monitoring and sample collection. Solely granites underlie the
area. The premonsoon water levels ranged from 1.54 to 13.21
mbgl and post monsoon water levels ranged from 1.16 to 9.88 mbgl and the
seasonal fluctuation (1994-95) ranged from 0.16 to 5.60 m.
A total of 44
water samples, 20 no from dugwells, 21 from bore wells, 2
from Bhadra river and 1 from municipal water supply in two sets
were collected during pre-monsoon 1994. One set was
analysed in SWR office for 13 parameters and the other set
has been sent to Kerala region, CGWB,Trivandrum
for heavy metal analysis.
monsoon 1994, a total of 47 water samples were collected in
3 sets. Sources of sampling was 21 from dugwells, 18 from
bore wells, 2 from river Bhadra, 1 from Municipal
water supply, 1 from canal and 4 no.s from effluent samples. One
set of samples were analysed in SWR office, one set was sent to Kerala
region, Trivendrum for heavy metal analysis and third set
was submitted to Sriram institute for industrial research, Bangalore
for analysing selected parameters.
The key wells
were got surveyed to determine (1)reduced levels of ground
water levels to know flow direction and (2) to establish the
relationship of river Bhadra with the ground water in the
area. The study shows that elevation of W.T lies between 565 to
611 m above sea level and the river Bhadra in this section is
effluent in nature and receives water from surrounding
ground water reservoir.
A multi disciplinary
ground water project was carried out with Canadian Assistance (1971 –
1975) envisaged to develop methods of ground water resource evaluation,
mainly for granitic and basaltic terrains covering parts of Andhra
Pradesh and Karnataka which covers an area of 505 sq.km in parts of
Gulbarga and Bidar districts of Karnataka.
Vedavathi River Basin
Project (VRBP) was taken up during 1975-80 covering an area of 19,000
sq.km. falling in parts of
Chitradurga, Chikamagalur, Hassan, Shimoga, Bellary and Tumkur
districts. The aims of the project studies were to develop methodology
for scientific and rational development of ground water in
crystalline terrain and for quantification of ground
water resources and determination of Specific yield percent
of the formation and minimum rainfall required for recharging the
ground water body.
Ground water evaluation was carried out during 1979-81 in trap Bhima crystalline fringe areas and Kaldgi formation (sandstone, shales and limestones) in Gulbarga and Bijapur districts by drilling wells. The studies helped in locating fractures in different depths in the area.
Under the World Bank assisted hydrology Project constructed piezometers for continuous monitoring of ground water levels using digital water level recorders were taken up.
along with MGD, Govt.of Karnataka have drawn a plan to construct 805
Piezometers in Karnataka. The CGWB participation involves analysis
of NHS for water level and water quality data. The basis for
selection of sites for the piezometers construction is as follows.
Optimisation study for PZ density location
Depth of existing NHS location
Water level changes over a period of time.
Dark and grey blocks
Quality considerations in respect of fluoride and nitrate.
Based on the analysis of historical data of water levels the optimum number of observation station decided for CGWB in Karnataka is 305 Piezometers.
URBAN GROUND WATER MANAGEMENT
and Hubli urban area: Ground water studies in Urban agglomeration has
become essential, since the demand of the growing population and high
growth rate of industries is creating a remarkable change of scenarios
in the present environment. Hence
urban ground water management studies have been taken up. An area of
190sq.km was covered covering Dharwar and Hubli cities in Dharwar
district. The area is characterized by semiarid climate with an average
annual rainfall of 838mm and it is underlain by schistose
formations(Schists, Grewackes, shales and ferruginous quartzites) of
Dharwar super group of Archaean age. Ground water occurs under water
table conditions in weathered zones and under semi confined conditions
in deep-seated jointed formations. Depth of weathering varies from 5 to
Twenty-five key observation wells have been established all over the urban area for repeat measurements of water levels 4 times in a year to know the changes in the ground water regime. The premonsoon water levels vary from 3.5 to 16.54 mbgl and postmonsoon water levels vary form 1.81 to 14.19 mbgl. There are 6 NHS in the twin cities. The general trend of water levels in these NHS shows that two stations show falling trend and other stations maintain steady trend.
understand the quality of ground water 32 water samples were collected
and submitted for chemical analysis. The general quality of ground water
is good and potable for domestic purposes.
INLAND GROUND WATER SALINITY STUDIES
area of 2800 sq.km out of geogrpahical area of 2829 sq.km of Navalgund ,
Dharwad district and Nargund and Ron taluks of Gadag district(Under
district ground water management studies) was selected for inland ground
water salinity studies.. In order to have precise information on the
extent of saline aquifers a total of 54 water samples were collected
from ground water abstraction structures for detailed chemical analysis.
During the course of study it is found that certain factors which might
have influenced the relative ground water salinity in the aquifers of
Net balance between annual evaporation, precipitation and run
Rate of local rock weathering and solution with resultant
formation in the soil of water-soluble salts forms the decomposed
Salt content transported in the region by streams and rain from
Permeability and hydraulic gradient of the aquifer.
The rate of groundwater circulation and rate of salt accumulation
in the aquifer body from infiltrating water.
Poor permeability of the soil with major area covered by black
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