Analysis of hydrogeophysical properties of aquifer and reserve estimation for sustainable development of Groundwater in Kewta Watershed, Hazaribagh


Sustainable Development of Groundwater
  1. Dugwell
    Based on water-table, depth of weathered material & its saturation, generalised yield prospects and analysis of hydro-geophysical properties of aquifer at depth of 11m helped in identifying the area most suitable ( 195 ha. i.e. 6.60 per cent of study area), suitable ( 310 ha., 10.16 per cent ) and marginally suitable ( 261.4 ha., 8.82 per cent of study area ) for groundwater development through dugwell ( Fig. 4 and Table - 1 ) . Suitable zone is an area where large-scale dugwell development is possible without disturbing the regional groundwater resources. In the less suitable area besides groundwater development stress should also be given on development of surface water harvesting structures. Similarly in marginally suitable area more stress should be given on development & utilisation of surface water resource and groundwater development should be given lowest priority.


    Fig. 4 Dugwell development feasibility map of study area

  2. Dug-cum-borewell
    Similarly area suitable for dugwell cum borewell has been identified which has been further cateogrised into different prospect zone ( Fig. 5 and Table - 1 ) i.e. most suitable ( 118 ha., 3.98 per cent ), suitable ( 338 ha., 11.42 per cent ) and marginally suitable zone ( 672 ha., 22.70 per cent ). The development as per feasibility map will reduce the chance of over exploitation of groundwater in area where aquifer is not suitable for dugwell cum borewell development.

  3. Deep borewell


    Fig. 5 : Dugwell cum borewell development feasibility map of study area

    Based on DBTM and hydro-geophysical parameters, total 15. deep borewell sites have been identified which is supposed to provide sustainable yield without affecting the regional groundwater environment. Most of the sites are located in the broader fracture zones or in the sub-surface basins where high recharge to the aquifer is expected.


Groundwater Development and Management Possibility
In the entire Kewta watershed ( 2961 ha ), 362.42 ha.m replenished utilisable groundwater reserves are available. The utilisable groundwater reserve has potential to provide irrigation to 906.00 ha (30.60 per cent ). Besides that huge amount ( 830 ha. m ) of utilisable groundwater reserves lies below the existing dugwell depth ( i.e. 10 m b.g.l. ) and basement surface. This untapped groundwater reserve has potential to irrigated 2075 ha. (70 per cent ) land ( Table - 2. ). But this untapped groundwater reserves can only be utilised when suitable recharge mechanism will be developed for balancing the intake and outtake from the aquifer.

Table - 1: Feasibility for Dugwell and Dug-Cum-Borewell Development

Dugwell Development Dug-Cum-Borewell Development

Areal extent Per cent Areal extent Per cent

(ha.) ( ha. )

Category

Most suitable zone 195.00 06.60 118.00 03.98

Suitable zone 301.00 10.16 338.00 11.42

Marginally suitable 261.00 08.80 067.00 22.70

Not suitable zone 2204.00 75.42 1833.00 61.90


Table - 2: Groundwater Reserve Estimation

Area of watershed ( ha ), (under consideration) 2961

Aquifer effective porosity / specific yield (per cent) 5.94

Average generalised seasonal fluctuation of water table ( m b.g.l.) 5 - 10

Replenished groundwater reserve ( ha. m ) 426.38

Utilisable groundwater reserves ( ha. m ) 362.42

Irrigation potential of utilisable groundwater reserves (ha) 906.05

Volume of aquifer material between two extreme of water table ( ha.m ) 8489.14

( i.e. 5 - 10 m b.g.l. )

Volume of aquifer material below 10 m b.g.l up to basement surface ( ha. m ) 16434.90

Utilisable groundwater reserve lying between 10 m b.g.l. up to basement

surface ( ha. m ) 830

Irrigation potential of available groundwater reserves below the 10 m b.g.l ( ha ) 2075

Conclusion
The analysis of hydroheophysical properties of aqufier in hard rock area has helped in understaing the aquifer properties with limited geohydrological inputs. On the basis of hydrogeophysical properties, study area has been cateogarised in different zones for groundwater development and management. Further DBTM has helped in estimating the groundwater reserve beyond the replenished reserve by estimating the entire volume of aquifer above the basement surface. Results indoicate that the groundwater reserve lying below the lower extrem of watertable ( pre monsoon ) which not replenished at present has potential to irrigate 2075 ha of land. Therefore there is enough scope for providing irrigation through groundwater. This can be utilised only when recharge to the aquifer will increased simultaneouly. The sub-surface basin may be used for retrieval and storage of groundwater. DBTM has helped in understanding the lineaments derived from remotely sensed data in better manner.

Acknowledgments
 Authors are thankful to Prof. D. P. Singh, Project Director, Bihar Council on Science and Technology, Patna for giving constant encouragement for research work. Authors are thankful to Deptt of Science and Technology, Govt. of India for providing financial assistance to the project.

References
  • DST - CSRE ( 1999 ). GRAM++ Window based GIS Package, Deptt of Science & Technology, New Delhi.
  • Kumar, Ashok, Sinha, Ranjan and Prasad, B. B. ( 1997 ). Digital Basement Terrain Modeling (DBTM) - a tool for sustainable utilisation and management of groundwater in hard rock area. Nat. Conf. on Emerging Trends in Development of Sustainable Groundwater Sources held at JNTU, Hyderabad from Aug. 27-28, 1997.
  • Kumar Tomar Savita and Prasad L.B. (1999 ). Groundwater prospects analysis through hydrogeophysical parameters and hydrogeomorphic zonation - A case study in parts of Kewta watershed, Upper Barakar Basin, Bihar. Seminar on Earth System Sciences in the next millennium, IGU, Pondicherry, Dec. 21-23.
  • Rangarajan …(2000). Personnel communication on groundwater recharge study using Nuclear tracer techniques for measurement of natural recharge in hard rock terrain.
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