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Project Title:
Assessment and Management of Groundwater Resources of Purulia District of West Bengal

Thematic Area:
District level groundwater resources assessment and Management for developmental planning

Location:
Latitude: 22040’N - 23045’N 
Longitude: 85055’E-86055’E 

Objective:
* To create comprehensive database on the following hydrological parameters of Purulia district:

(i) Status of water table during post monsoon and pre-monsoon periods and its fluctuations in different hydrological formations based in water table data will be collected from other agencies like CGWB, SWID etc.
(ii) Delineation of principal aquifers along with other morphological variations.
(iii) Hydraulic characteristics of the water bearing formations
(iv) Remote sensing studies for locating weak zones and for understanding factors influencing groundwater movement in different geomorphologic setup.
(v) Locating new bore-well sites in the basis of electrical sounding data in the water scarce areas.
(vi) Generation of groundwater flow models to study the effects of the existing and proposed water harvesting structures on groundwater regime particularly in the drought-prone areas.
(vii) Detailed chemical quality assessment of groundwater for different aquifers.
(viii) Block-wise assessment of groundwater recharge, present utilization status and the balance available for further development and management. 
Preparation of thematic maps on various groundwater related parameters
* To evolve schemes of augmentation of groundwater resources by artificial recharge and laying out water harvesting structures and predicting changes in groundwater regime.
* To formulate a rational groundwater development policy for immediate requirements as well as long term need.


Abstract:
The project, which was sponsored by the DST under the NRDMS programme, was carried out from July 1994 to June 1997. Purulia district is a part of Chhotonagpur plateau and is underlain mainly by Precambrian metamorphics excepting a small area in the northeastern part where sedimentaries of Gondwana age are exposed. Adjacent to major rivers and streams, unconsolidated Quaternary sediments occur as discontinuous patches.
Groundwater in the district occurs at shallow depth under water table condition within the weathered mantle, fractured zone of hard rock and narrow zone of unconsolidated sediment along major valleys. The potential aquifers comprise two units, viz (i) a weathered residuum which is in general 8-10 m thick, porous and unconsolidated, containing water in the interstices and (ii) underlying fractured hard rocks which stored water within zones of the secondary porosity. 
Large diameter dugwell pump tests in the Hanumata, Nangasai and Sanka sub-basins of the district reveal that the potentiality of the aquifer to transmit water was of low order and transmissivity value ranged between 2.42 and 11.61 m2/day. The specific yield value ranged between 0.79 X 10-1 and 2.82 x 10-1indicating that the aquifers were unconfined in nature. The average yield of dug wells in granite gneiss, mica schist and sandstone formations were 4.80 m3/hr, 0.92 m3/hr and 16 m3/hr respectively.
The water table in general was at depths varying between 6 and 8 m.bgl during pre-monsoon period and between 2 and 4 m.bgl during post-monsoon period. In the southern and extreme northeastern parts, the water table was at depths greater than 8m.bgl. Water table, in general fluctuating between 3 and 4 m.bgl. Greater fluctuation of water table was observed mostly in mica schist and Gondwana terrain and relatively lower fluctuation was recorded in granitic terrain. The long term water table behaviour projected from 11 network stations of C.G.W.B for the last 16 years showed 3 types of patterns viz. pre-monsoon falling, post-monsoon rising; pre-monsoon falling, post-monsoon falling and pre-monsoon rising, post-monsoon rising.
As per the standard of drinking water (BIS 10500, 1991), the groundwater of the district was fresh and potable. The Sodium absorption ratio, percent sodium and electrical conductivity indicated that the groundwater was in general suitable for irrigation of most crops on almost all types of soils.
Scanning of bacteriological test results revealed that water samples collected from tubewells located at selected villages were bacteriologically 100% safe in only 5 blocks. In the remaining 15 blocks the number of unsafe water samples varied between 10-58%. All the water samples collected from dugwells located at selected villages in Puruliya district were bacteriologically contaminated and hence not fit for drinking. 
Taking into consideration the above facts the following management plan was proposed for Purulia district
First phase: Blocks, where construction of water harvesting structures should be immediately implemented, are Banduan, Baghmundi, Jahald-II and Puncha.
Second phase: water harvesting structures to be implemented to Manbazar-II, raghunathpur-I and Kashipur blocks.
Third phase: water harvesting structures to be implemented to Jaipur, Arsha and Puruliya –II blocks.

Highlights/Findings:
First phase: Water harvesting structures should be immediately constructed in Bandwan, Baghmundi, Jahald-II and Puncha.
Second phase: Water harvesting structures to be constructed in Manbazar-II, raghunathpur-I and Kashipur blocks.
Third phase: Water harvesting structures to be constructed in Jaipur, Arsha and Puruliya –II blocks.

In Purulia district, most of the open dug wells dried up during peak summer and there was a severe scarcity of drinking water. So it was suggested that the depth of dugwells should be increased and in-well boring should be done at the bottom of the well to increase the yields.
Pump tests carried out on dug wells revealed that the potentiality of the aquifer to transmit water was of low order. Therefore it was suggested that the dugwells should be appropriately designed to increase the flow of groundwater into the wells.
The water table in many parts of the district revealed a falling trend in the postmonsoon period. Groundwater reserve depletion took place substantially in four blocks viz. Banduan, Baghmundi, Jhalda-II and Puncha compared to that of 1978 and 1989. In Manbazar-II, Raghunathpur-II and Kashipur blocks, the groundwater resource came down compared to that of 1989. In Jaipur, Arsha and PuruliaII blocks there was a trend of falling groundwater potential over the years. Hence, regulation of groundwater draft should be immediately enforced to check the excess draft and to ensure sustainable supply.
With rising population, the demand of water for irrigation was also rising. The only way by which this demand could be met was through use of water harvesting structures.
It was recommended that the groundwater and harvested surface water should be economically used because they had limited potential, especially in the western and eastern parts of the district. 
Artificial recharging of groundwater by recycling of sewage and wastewater after necessary treatment through pits, shafts and recharge wells to enhance the natural supply of groundwater should also be adopted after detailed studies.
The concentration of iron at places was above the desirable limit of BIS 10500, 1991 (i.e. 0.3 mg/l), especially in the northeastern, northern, northwestern, central and south-central parts of the district and hence excess iron should be removed by installation of iron removal plants.
In the northeastern, eastern, northern, central, south-central and northwestern parts of the district the TDS concentration of groundwater was high; use of this water of irrigation might cause salinity hazards in the long run.
Water samples from dugwells and tubewells are bacteriologically contaminated. The most important improvement, which could be made to an existing dugwell, is by having a bucket permanently hanging in the well from a windlass so that it is not taken home or put on the ground. The bucket could be made of collapsible rubber so that it is less likely to be put on the ground or stolen. Pollution could be avoided by covering the well with a concrete slab and connecting the bucket and a tap fitted in the well head by plastic hosepipe. Tube wells can be protected from pollution by a concrete slab at least 2 m across, used as a base for the pump. In addition tubewells should be properly constructed so that polluted water did not percolate move downward through the annular space between the casing and the borehole well. The casing pipes used should also be free from cracks and leaks.

Data used:
Survey of India toposheets
Satellite images of IRS1B & LISS-II
Bore-hole log data
Vertical Electrical Soundings (VES)
Groundwater samples data for chemical analyses
Pump test data for various locations
Depth to water level data and meteorological data (rainfall).

Output:
The functions of the ‘Water Users’ committee should be as follows:
* To identify the suitable sites for the sinking of groundwater abstraction structures.
* To select and train woman caretakers for maintenance of the groundwater structures so that they can do the same without external dependence.
* To maintain the tubewells/dugwells, the beneficiary should pay a certain initial fixed amount either in cash or in kind as decided by the committee at the start and subsequently 25-50 paise from every family every month to create a maintenance chest fund.
* To keep account and maintain all records in this connection.
* To keep the surroundings of the abstraction structures specially dugwells neat and clean and also educate the people on how to handle the drinking water during collection and to preserve the same at home.
* To arrange at intervals, to get the water examined to safeguard the water quality of the tubewell/dugwell.

Date of Project completion:
June 1997

Total cost of project:
Rs. 11,05,000/- (including one more project: "Assessment and Management of Groundwater Resources of West Medinipur district, West Bengal")

Project Investigator:
Honorary Secretary
Center for Study of Man & Environment,
Parivesh Kendra, CK-11, Sector-2, Salt Lake, 
Kolkata-700 091
E-Mail: csme[at]vsnl[dot]net
Phone: (033) 23210861, 23590781