Dependency on groundwater for drinking and domestic purpose has increased.
By
Dr. Nitish Priyadarshi
Geologist.
nitish.priyadarshi@gmail.com
Introduction:
Water is essential for life- all living organisms contain water. In fact
most living organisms consist of over 60 percent water.
Through out his brief history on earth, man has depended on three basic
natural resources for his survival: air, land and water. Of these three, none
has been more abused and neglected by man than water. Yet without water, the
land produces nothing; without water, life vanishes from the face of the earth.
Civilizations arose and have prospered for millennia where water was abundant.
The Nile valley is a prime example. When water disappeared, civilizations
withered and died. Mesopotamia is a classic example.
The utter human dependence on water is exemplified by the fact that man
can survive for five weeks without food, but he dies after only five days
without water. If the water supply of a human being is cut off for just a few
days, he will die of dehydration long before the water is completely evaporated
from his body. Water vapor is lost with every breath, and we cannot avoid
breathing.
In recent years due to increasing contamination of surface water bodies,
dependency on groundwater for drinking and domestic purpose has increased many
fold. But these water sources are now badly affected with global warming.
Groundwater is depleting day by day due to effect of rising temperature and
urbanization.
The excess soil moisture that saturates subsurface soil or rock and migrates
downward under the influence of gravity. In the literal sense, all water below
the ground surface is groundwater; in hydrogeologic terms, however, the top of
this saturated zone is called the water table, and the water below the water
table is called groundwater.
Ranchi the capital city of Jharkhand state of India
is located at 23.350 N and 85.330 E. The total area covered by Ranchi-Municipal
area is about 141 square kilometers and the average elevation of the city is
645 m above Mean Sea Level (MSL). As of 2001 India census Ranchi had a
population of 846,454.
Water supply, in adequate quantity and at desirable quality, is essential for any sustainable urbanization. Water supply in Ranchi dates back to more than 50 years ago.
There are three main dams ( Hatia, Rukka, and Kanke dam) from where the water is supplied to the city. Surface water is always vulnerable to pollution. People of Ranchi are dependent more on purer source like groundwater. Of the total consumption more than 60% comes from groundwater storage. Due to increasing population more pressure has developed on groundwater from the aquifer beneath the city.
The process of urbanization and industrialization from last 20 years has caused changes in the water table as a result of decreased recharge and increased withdrawal. Many of the small ponds which were main source of water in the surrounding areas are now filled for different construction purpose affecting the water table. Lots of DEEP- BORING in the Ranchi city has also forced the water table to move down as well as Ranchi plateau.
Water supply, in adequate quantity and at desirable quality, is essential for any sustainable urbanization. Water supply in Ranchi dates back to more than 50 years ago.
There are three main dams ( Hatia, Rukka, and Kanke dam) from where the water is supplied to the city. Surface water is always vulnerable to pollution. People of Ranchi are dependent more on purer source like groundwater. Of the total consumption more than 60% comes from groundwater storage. Due to increasing population more pressure has developed on groundwater from the aquifer beneath the city.
The process of urbanization and industrialization from last 20 years has caused changes in the water table as a result of decreased recharge and increased withdrawal. Many of the small ponds which were main source of water in the surrounding areas are now filled for different construction purpose affecting the water table. Lots of DEEP- BORING in the Ranchi city has also forced the water table to move down as well as Ranchi plateau.
Groundwater in Ranchi city:
Groundwater in Ranchi city is mainly stored here in secondary porosity features or void spaces developed as result of weathering, fracturing, jointing, shearing or faulting phenomena. The gneisses and granitic rocks with associated schists and quartzites constitute the main consolidated rock terrain of Ranchi district.
Major portion of Ranchi city which is part of the Chotanagpur Plateau occupied by hard rock which are devoid of primary porosity and occurrence and movement of groundwater is controlled by the joints, fractures and fissures present in them.
During the long span of geological history these rocks have been deformed and tectonised in many ways including deep erosion.
In Ranchi city water table in the consolidated formations is now at its lowest from April to June. Water table is at its highest peak during August, gradually stabilizing in the month of November.
Sources of groundwater recharge in Ranchi city and the other parts of Jharkhand State is the vertical percolation of rain water. Although city experiences about 1000 to 1200 mm rainfall annually, the rate of vertical percolation is hindered by the presence of highly weathered and metamorphosed rocks. The Ranchi plateau gradually slopes down towards south east into the hilly and undulating region of Singhbhum. Due to this uneven topography the rain water are lost through surface runoff resulting in less water percolation below the surface. The thin soil layer of Ranchi plateau which is becoming more thin due to weathering is gradually loosing its water retaining capacity, Moreover, present land development practices in the recharge area and natural canals or rivulets in and around the city is also reducing the natural recharge significantly. More than 40% of the rain water is lost in the form of surface runoff. The rate of decline ranges between 1m/year to 5m/year at different observation locations within the city.
Groundwater in Ranchi city is mainly stored here in secondary porosity features or void spaces developed as result of weathering, fracturing, jointing, shearing or faulting phenomena. The gneisses and granitic rocks with associated schists and quartzites constitute the main consolidated rock terrain of Ranchi district.
Major portion of Ranchi city which is part of the Chotanagpur Plateau occupied by hard rock which are devoid of primary porosity and occurrence and movement of groundwater is controlled by the joints, fractures and fissures present in them.
During the long span of geological history these rocks have been deformed and tectonised in many ways including deep erosion.
In Ranchi city water table in the consolidated formations is now at its lowest from April to June. Water table is at its highest peak during August, gradually stabilizing in the month of November.
Sources of groundwater recharge in Ranchi city and the other parts of Jharkhand State is the vertical percolation of rain water. Although city experiences about 1000 to 1200 mm rainfall annually, the rate of vertical percolation is hindered by the presence of highly weathered and metamorphosed rocks. The Ranchi plateau gradually slopes down towards south east into the hilly and undulating region of Singhbhum. Due to this uneven topography the rain water are lost through surface runoff resulting in less water percolation below the surface. The thin soil layer of Ranchi plateau which is becoming more thin due to weathering is gradually loosing its water retaining capacity, Moreover, present land development practices in the recharge area and natural canals or rivulets in and around the city is also reducing the natural recharge significantly. More than 40% of the rain water is lost in the form of surface runoff. The rate of decline ranges between 1m/year to 5m/year at different observation locations within the city.
As Ranchi is becoming one of the important business
center in Eastern India there is a rampant increase in construction and expansion
of city. Due to inadequate water supply from the dams, dependency on ground
water is increasing. Over pressed zones are Upper Bazar, Main Road, Ratu Road,
Piska More, Chutia, Hindhpirhi, Circular Road, Burdwan Compound, Lalpur and
Harmu Road.
Objective:
The main objectives of
Rain Water Harvesting are:-
• Increasing the
availability of ground water during periods of requirement.
•Preventing depletion of
ground water reservoirs in areas of over exploitation.
• Improving quality of ground water through dilution.
Rainwater
harvesting is the collection, storage and injecting precipitation down in the earth of for later human use. This project focuses on
the selection of the site and rainwater harvesting system located at the
different rickshaw pullers garage located in different areas of Ratu road and
Piska more in Ranchi city. The information collected from this project will be used to build a
template for designing a rain water harvesting system that can be placed in the
selected areas.
Fig.1 Depletion of ground water.
Fig. 2. Structure of rain water harvesting.
Fig.3. Depleted water in a well in Piska More, Ranchi.
Rickshaw pullers are the most affected people as they are more dependent on surface and well water which is polluted and gets dry in summer season.
Till about thirty years back,
the areas surveyed used to be unpaved
and the rain falling on these areas would percolate into soil and remain there
for being drawn through shallow open wells. With the proliferation
of flat complexes, these areas been covered, resulting in stopping of percolation of rain water into the soil. But on
the other hand the use of ground water has risen immensely. With Increase in the number of deep bore wells, the
shallow wells started drying up. The reason is that no sincere attempt was made
to re- establish the ground water table to its original level during
monsoons.
Rooftop rain water harvesting was
suggested in the surveyed areas. Out of 30 sites 10 sites were selected as the
rickshaw pullers were using dug well waters for their daily purpose. Rooftop catchments is the most
basic form of this technology, rainwater is collected in simple vessels at the
edge of the roof. Variations on this basic approach
include collection of rainwater in gutters which drain to the collection vessel through down-pipes constructed for this purpose,
and/or the diversion of rainwater from the gutters
to the settling tanks/percolation
tank or absorption tank filled with sands and cobbles and pebbles
working as water filters. As the rooftop is the main catchment
area, the amount and quality of rainwater collected depends on the area and
type of roofing material. Reasonably pure rainwater can be collected from
roofs constructed with galvanized corrugated iron, aluminum or asbestos
cement sheets, tiles and slates. Roofs with metallic paint or other coatings are
not recommended as they may impart tastes or color to the collected
water. Roof catchments
should also be cleaned regularly to remove
dust, leaves and bird droppings so as to maintain the quality
of the water.
Settling tanks
for collecting rainwater harvested using guttering may be either
above or below the
ground. Precautions required in
the use of se tanks include provision of an adequate enclosure to minimize contamination from human,
animal or other environmental
contaminants, and a tight cover to prevent algal growth and the breeding of
mosquitoes.
Sr.No
|
Garage Name
|
Garage owner name
|
Address
|
No.of rickshaw
pullers staying in the garage
|
Water Harvesting
status
|
Remarks
|
Date of visit
|
1
|
Vijay
|
Vijay
Tirkey
|
Near
Krishi Bazar, Pandra, Ranchi
|
50
|
Yes;
Important
|
29-01-2018
|
|
2
|
Amit
|
Amit kr.
Bhagat
|
Piska
More
|
70
|
Yes;
Important
|
29-01-2018
|
|
3
|
SLK
|
Suresh
Kachhap
|
Piska
More
|
15
|
No
|
Shed not
much and well is not owned by owner but garage owner has himself made some
water harvesting system.
|
29-01-2018
|
4
|
Pawan
|
Pawan
Sharma
|
Piska
More
|
40
|
Yes
|
29-01-2018
|
|
5
|
BPK
|
Suresh
|
Karam
toli
|
40
|
No
|
Has
naturally available water resources which maintains the water level.
|
29-01-2018
|
6
|
JPB
|
Jagdish
Bagla
|
Piska
More
|
20
|
Yes;
Important
|
30-01-2018
|
|
7
|
Guddu
|
Rajiv
Agarwal
|
Near
Uphar cinema, Ratu road
|
30
|
No
|
Consist
of self built water system which maintains water level
|
30-01-2018
|
8
|
Mitu
|
Jayant Agarwal
|
Near
Uphar cinema, Ratu road
|
30
|
No
|
Land too
low so naturally land absorbs water, sheds are not available in much
|
30-01-2018
|
9
|
MPS
|
Madhukar
Singh
|
Near
Pahadi Mandir
|
25
|
No
|
No well;
no boring and monthly rented land
|
30-01-2018
|
10
|
Sunil
|
Sunil
Yadav
|
Near
Pahadi Mandir
|
50
|
No
|
Less
possibility of holding rain water
|
30-01-2018
|
Acknowledgement:
This survey was carried out with the help of Mrs.
Aprajita Mishra and Smita Dasgupta of Maitri India,
Ranchi.