|
Vol - I , ISSUE - VIII [ February 2012 ] Article : Spatio-temporal Analysis of Groundwater Resource using GIS: A Case Study of Murshidabad District, West Bengal, India Author : Debabrata Mondal Abstract :
In modern time, Geographic Information System (GIS)
has been considered as a powerful tool in mapping of ground water resources. The
study area Murshidabad district has experienced a remarkable change in ground water
table throughout the decades. The present paper is an attempt to evaluate the decadal
trend of ground water fluctuation in several blocks of the district along with their
possible causes by using the data from secondary sources and processed them through
GIS software.
Key words: GIS, Ground water
table, Ground water resource.
INTRODUCTION
Groundwater is
the only reliable water resource for domestic, as well as for agriculture practice
in those countries where rainfall is erratic. Since the country of India has its
economic base lying on agricultural sector, a major emphasis has been given to accelerate
the agricultural production without concerning the environmental issues for feeding
its huge population. From the last few decades gradual depletion of groundwater
supplies as a consequence of continued population growth and initiation of Boro
cultivation over the Gangetic moribund delta has now been considered as an emerging
problem. Now a day’s Murshidabad district is also facing this invisible hazard of
groundwater depletion. In this regard monitoring, analyzing of groundwater is necessary
for assessing its quantity.
Ground water fluctuation map is an important tool for analyzing the temporal as well as spatial changing pattern of groundwater resources. In this regard Geographic Information System (GIS) plays a crucial role for analyzing, model building and interpreting the groundwater data. In order to obtain long term groundwater information, GIS has been used in this study to visually and spatially analyze groundwater data.
ABOUT THE STUDY AREA
The present
study area Murshidabad district is situated in the lower part of the Ganga basin
in the hearth of West Bengal. The district can be delimited by 23º 43' to 24º 52'
north latitude and 87º 49' to 88º 44' east longitudes covering an area of 5324 Sq
Km. It consists of 26 blocks and 255 Gram Panchayat with 2210 villages.
Geology:
The west
of the Bhagirathi river i.e. Rarh area has been formed by the depositional work
of Ajoy-Damodar-Mayurakhi river system constituting older alluvium of Pleistocene
age. It consists of stiff and plastic like clay and calcareous materials which are
susceptible to laterization process at the surface area. The east of the Bhagirathi
river is characterized by recent to subrecent alluvium deposits of the Ganga river
system.
Soil:
The soil
found in the Rarh area is of lateritic clay and calcareous nodules of the Sub-Vindhayan
region whereas the Bagri region is characterized by light alluvial fertile soil.
Hydrogeological set up:
Murshidabad
district belongs to hot and humid climatic type driven by south-west monsoon wind.
The maximum rainfall occurs at the later half of June. In addition, pre-monsoon
rain is received during the month of March-April. The annual rainfall ranges from
about 1100mm to 1500mm. May is the hottest month during which the maximum temperature
fluctuates between 40º-43ºC. January, the coldest month experiences a huge fall
in temperature up to 8ºC. A systematic hydrogeological survey conducted by CGWB,
1994 has revealed that the eastern part of Bhagirathi river is constituted by unconfined
aquifer and occurred down to 90-350 mbgl. Ground water occurs in the western part
of Bhagirathi river under semi confined condition within the deeper horizon of sand
and gravel having different texture where the main aquifers are found at greater
than 150mbgl.
OBJECTIVES
Ø
To build a model that will create a contoured water
table surface map.
Ø
To create groundwater fluctuation maps.
Ø
To evaluate groundwater fluctuation in different decades.
Ø
To assess the reasons behind such fluctuation in Murshidabad
district.
METHODOLOGY
I.
The study
of decadal (1980, 1990, 2000, and 2010) condition of ground water was conducted
based on secondary data of 114 network stations in different blocks of the study
area supplied by Senior Geologist, SWID, Berhampore, Murshidabad.
II.
The ground
water data of different stations has been integrated in GIS environment as point
vector layer, and then ground water contour map has been generated for the consecutive
periods.
III.
With the help of ‘Feature Info Tool’
in Global Mapper 10 software, the maximum and minimum depth of water level has been
procured for different years.
IV.
Groundwater fluctuation maps were developed by overlaying two individual groundwater
contour maps and the rise-fall patches were generated by subtracting the most recent
values from older one for the all blocks. This process is accomplished by the Overlay
Analysis Operation in PCI Geomatica 10.1.
V.
Finally, the trend of ground water fluctuation has
been generated in tabular format.
RESULTS AND DISCUSSION The Green Revolution has been introduced in Murshidabad District in a massive way in the late1980s. Due to erratic character of rainfall and lack of canal irrigation agricultural sector was highly dependent upon groundwater irrigation. As a consequence of which most of the blocks of western part has experienced a mark seasonal as well as decadal lowering of groundwater level.
Source:
Computed by author
The
decadal trend of ground water fluctuation, processed through tabular
format (Table-1.). This table reveals the following facts. 1. In
the Rarh area, where the decadal fluctuation of ground water is much
greater than Bagri. 2. The
water level fluctuation map of 1980-90 (fig.1) has depicted few numbers of
blocks with fall of water level ranges between -4.5 to -6.5, contrary to
this there is higher magnitude of fluctuation in the period of 2000 to
2010 (fig. 3) due to huge pump out of ground water for irrigational
practices. 3. Due
to flood of 2000 the average water level has been raised, so most of the
blocks suffered water logging condition. 4. The
water logging condition is found in the block of Farraka, Suti-I, Suti-II
and Samsergang during three consecutive decades. Where a rise has
been. 5. The
continuous significant decline of groundwater level in the Rarh area
during three decades has revealed a clear indication of disparity between
recharge and discharge. Table-2:
Depth of water level in pre and post monsoon period in different
years
*Metre
Below Ground Level Source:
Computed by author Table-2
shows the changing pattern of ground water level in different consecutive
period in Rarh and Bagri region of Murshidabad. The depth to water level
in pre-monsoon period in Rarh area varies from 1.17 to 15.35 mbgl while
during post-monsoon it is from 0.79 to 11.32 in 1980 but this figure
gradually changed in the year 2010 and representing a huge change of depth
of water level whereas the picture of Bagri is quite different from that
of Rarh. During post monsoon, 2010 the depth of water level, in general,
ranges between 3.5 to 9.5 mbgl in major blocks of Bagri region. In the
same time period Nabagram, Kandi Khargram blocks of Rarh has found deeper
water level (22.2 mbgl). CONCLUDING
REMARKS The
huge quantity of ground water abstraction by means of irrigation water has
laid upon a diverse effect upon ground water table of Murshidabad
district. In recent times, various reports categorized the district as a
highly arsenic prone area. It may be convenient to say that ground water
depletion as a consequence of faulty agricultural practice and misuse of
water in domestic purpose has directly or indirectly influenced the
contamination of arsenic in our drinking water. The present study highly
appreciates this problem and asks for kind attention of State as well as
Central Government authorities to take pilot project in sustainable use of
water resources by encouraging the use of surface water in irrigation and
domestic purpose. REFERENCES:
1)
Ghosh,
A. K. (2007): ‘Groundwater
Information Booklet, District: Murshidabad (Arsenic affected area), West
Bengal’, published by Central Ground Water Board, Eastern Region,
Kolkata. 2)
Jha,
B.M., Sinha, S.K. (2009):
‘Towards Better Management of Ground Water Resources in
India.’
in Bhu-Jal News, vol.24, no.4, pp.1-20 3)
Mukherjee,
A., Tewari, D., Verma, J.R., Ray, S.S.R.K. and Devangan, R. (2009):
‘Geogenic
Arsenic Contamination to Ground Water in Part of Ambagarh Chowki Block,
Rajnandgaon District, Chhattisgarh.’ in
Bhu-Jal News, vol.24, no.2 &3, pp.40-58. 4)
Napoli,
N.,Laton, W.R. (2006):
‘GIS; A Tool for Determining
Long-term Changes in Groundwater Storage A Case Study, Lucerne Valley
Groundwater Basin’ in http://www.grac.org/GIS.pdf (accessed on
10.12.2011). 5)
Roy,
A., Shekhar, S., (2009): ‘Ground
Water Issues and Development Strategies In West Bengal’
in Bhu-Jal
News, vol.24, no.1, pp.1-17. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
