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Hydrogeomorphological Mapping

A C Pandey


A C Pandey
Haryana State Council for Science & Technology, Chandigarh.
[email protected]

M S Nathawat
Birla Institute of Technology, Mesra, Ranchi (Jharkhand)

Water is the most vital requirement for mankind. The growth of any area is dependent on its natural resources of which land and water form the core of ecological system. The water resources of Panchkula district are under threat due to depleting water table, which is causing land-degradation.

The principal source of ground water recharge in the district is through rainfall, although the river and streams emerging from Siwalik hills also form a significant recharge source The advent of Remote Sensing has opened up new vistas in geological, geomorphological and structural mapping for ground water exploration.

The satellite imagery portrays an unbiased picture of the area providing integrated information on different terrain factors controlling the ground water regime. In the present study the ground water prospect zones in Panchkula district were delineated using remote sensing techniques.

Objective
The present investigation is undertaken to prepare hydrogeomorphological maps of the Panchkula district on 1:50,000 scale using satellite images to delineate the ground water potential zones.

Study Area
The Panchkula district is located in the northernmost part of Haryana State, bounded by 76° 48′ – 77° 10′ east longitude and 30° 27′ – 30° 57′ north latitude covering an area of 893 square kilometers. The district is mainly drained by the river Ghaggar and its tributaries.

The relief of the area ranges from the lowest of 305m over the plains to the highest elevation of 1353m over the Siwalik hills. The climate of the district is characterised by a hot and dry summer, a southwest monsoon season and cold season. The average annual rainfall of the district is 1100 mm. Soils of the district are excessively drained, highly permeable and have low to medium productivity.

Geology of the area
The geological milieu in the district represents the lithological formation belonging to the Indo-Gangetic plain and Extra-Peninsular regions ranging in age from Upper Miocene to recent. The Subathu Series consist of shale with occasional sandstone and limestone forms the oldest rock type of the area. The Tertiary group of rocks belonging to Upper Siwalik are dominated by thick boulder and conglomerate horizons whereas the rocks of the Lower Siwalik are characterised by grey sandstone, purple shale and clay. The recent sediments mainly represent thick pile of fluviatile, unconsolidated sediments. The general geological succession in the district is given in Table-1.

Hydrogeomorphology
Hydrogeomorphological mapping incorporates relationship of geomorphic units with their groundwater potential as interpreted from the landform characteristics (nature of landform occurrence, lithology, structure, inter-relationship with other units etc.) as well as sub-surface geology. The Hydrogeomorphological interpretation (fig.1) of the investigated area has been carried out on 1:50,000 scale with the help of Indian Remote Sensing (IRS) 1C, False Colour Composite (FCC) imageries (February & October 2000) and Survey of India topographical sheet (53 B/13,14,15 & 53 F/1,2,3). Based on image characteristics of landforms (tone, texture, drainage, size, association etc.), their genesis, occurrence and composition, the hydrogeomorphic units of the area are classified under fluvial origin, denudational origin and structural origin. The aerial coverage of different units and their water prospects are given in Table- 2.

Fluvial origin
Alluvial plain and flood plain constitute the main forms of fluvial origin in addition to valley fills and channel bars. These are characterised by very gentle sloping, thick deposits of river alluvium mainly pebbles, cobbles, boulders, sand, silt and clays. These units form the main source of ground water in the region. The alluvial plain extends south of piedmont zone occupying elevation of 300 to 350 m above msl. They have a southwestward slope with an average gradient of 1.5m /km. Units of fluvial origin cover 30.87% (275.67 sq. km.) area of the district of which 20.49% and 6.60% area belongs to alluvial plain and flood plain units respectively. Ground water can be tapped through shallow and deep tube wells in alluvial plains and flood plains. The wells tapping the flood plains generally give high yield with good quality of water.

Denudational origin
The relief features of Panchkula district are dominated by units of denudational origin, which covers 387.08 sq. km. (43.34%). Denudational hills, piedmont zone and intermontane valley constitute the main units of denudational origin. Denudational hills cover 21.09% area followed by piedmont zone and intermontane valley accounting for 13.42% and 8.83% of area of the district respectively. These act as the main recharge zone in the area.

Dedudational hills are characterised by steeply sloping, highly weathered hills mainly consisting of sandstone, shales and boulder beds. These occupy elevation between 400 to 600m above msl and have poor ground water potential.

The piedmont zone having width of 3 -10 km lies on the foot of Siwalik hills with elevation ranging from 320 to 500 m above msl. This zone is constituted by sediments brought by the turbulent rivers emerging from the hills. The piedmont zone has moderate slopes with 10m to more than 30m thick deposits of colluvial and alluvial sediments. It serves as a good recharge zone but cannot hold ground water due to steep hydraulic gradient.

The intermontane valley exists along river Sirsa extending to a length of 17.5 km. with a width ranging from 2.5 to 7.5 km. The valley is characterised by unconsolidated clastic sediments, derived from the adjacent hills. Intermontane valley has very good ground water prospects as it is being recharged by the surrounding hills as well as by the river water.
Table-1 General Geological Succession at Panchkula District

Group System Series Description of rock types
Recent Newer Alluvium Fluviatile unconsolidated sands, silts & clays of flood plain deposits.
Quaternary Upper Pleistocene Older alluvium Fluviatile deposits poorly sorted consist of silts, sands, gravels, clays with variable proportion of kankar.
—————————unconformity———————-
Lower Pleistocene Upper Siwalik Boulder conglomerate, coarse sands, grits and some clays.
Tertiary Upper Pliocene Pinjore Stage: Coarse grit, sandstone and conglomerate.
Middle Pliocene Tatrot Stages: Soft sand stones, clays and some conglomerate.
Lower Pliocene Lower Siwalik Dhok Pathan Stage: Brown sandstone, gravel beds, orange clay and shales.
Upper Miocene Nargi Stage: Hard and grey sandstone and subordinate shales.
—————————unconformity———————-
Eocene Subathu Grey & red shale with occasional sandstone and limestone beds

Structural Origin
The structural hills representing the geomorphic landforms of structural origin cover an area of 185.80 sq. km. Structural hills are constituted by massive sandstones, shale and limestones having prominent joints and fractures. The hills trend NW-SE attaining an altitude of over 500m above msl. These have slope towards southwest with an average gradient of 28 m/km. The structural hills have poor to nil ground water prospects because most of rain water which falls over them goes down-slope as surface run-off.


Fig. 1: Hydrogeomorphological interpretation

Table 2: Aerial coverage of mapped hydrogeomorphic units and their ground water prospects in Panchkula district

Hydrgeo morphic Unit Map symbol Description Groundwater prospect Area( sq km) %Area
A. FLUVIAL ORIGIN
Channel Bar CB Small alluvial patch forming part of the riverbed. Excellent 1.82 0.20
Valley fill shallow VFS Narrow depressions filled with alluvial and colluvial matter of shallow depth (<10m) Good 8.46 0.95
Flood Plain Deep FPD Narrow flat areas along the rivers formed of recent sediments (> 20m thickness) Excellent 29.58 3.31
Flood Plain Deep Ravenous FPD-R Highly dissected flood plain deep Good 0.11 0.01
Flood plain Shallow FPS Narrow flat areas along the rivers formed of recent sediments (< 10 m depth) Very Good 29.42 3.29
Flood plain shallow ravenous FPS-R Highly dissected Flood plain Shallow Good 0.08 0.01
Alluvial plain deep APD Very gently sloping plain of alluvial sediments >20m thickness occupying southern part of the district Very Good 115.72 12.97
Alluvial plain deep Ravenous APD- R Highly dissected Alluvial plain deep Good 14.04 1.57
Alluvial plain shallow APS Very gently sloping plain of alluvial sediment < 10m thickness occupying areas between APD and piedmont. Good 67.13 7.52
Alluvial plain shallow Ravenous APS-R Highly dissected Alluvial plain shallow Moderate 9.31 1.04
B. DENUDATIONAL ORIGIN
Piedmont Alluvial Deeply Buried PDD Moderately sloping zone of colluvial and alluvial sediments at the foot of the hills > 20m thickness. Moderate 55.51 6.22
Piedmont Alluvial Deeply Buried-Ravenous PDD-R Highly dissected deeply buried Piedmont Alluvial Poor 1.08 0.12
Piedmont Alluvial Shallow Buried PDS Moderately sloping zone of colluvial and alluvial sediments at the foot of the hills > 20m thickness. Moderate 63.25 7.08
Interrmon- tane Valley IV Narrow linear valley of river Sirsa having widths of 2.5 to 7.5 km, occupied by unconsolidated clastic sediments. Very good 78.84 8.83
Denudational Hill DH Weathered, eroded & Denuded Hills generally made of boulders, sandstone showing rounded crests and attaining relief of about 300m. Poor 188.41 21.09
C. STRUCTURAL ORIGIN
Structure Hill SH High rising NW-SE trending hills, with prominent joints, occupying the NE part. Poor – Nil 185.80 20.80
Water Bodies (Rivers, Ponds) 44.55 4.99
Total 893 100

Table 3: Depth to water table in Panchkula district

Depth Range (meters) Area (sq. km) % of total district area
3 – 10 286.84 32.12
10 – 20 271.747 30.43
20 – 30 20.533 2.30
Out crop area 313.984 35.15
Total 893 100

Table 4: Ground water prospect zones in Panchkula district

Ground water Prospect zones Area(sq. km) % of total district area
Excellent to Very Good 75.95 8.50
Very Good to Good 223.97 25.08
Good to Moderate 89.82 10.06
Moderate to Poor 128.70 14.34
Poor to Nil 375.29 42.02
Total 893.10 100.00

Groundwater Prospects
The groundwater in the district occurs under the unconfined water table conditions in the upper aquifers which are mainly formed of alluvium and semi-consolidated formations. In the deeper aquifer zones where the water holding formations are shale, silt and clay the ground water occurs in semi-confined to confined conditions. The depth of water level in the phreatic aquifer varies from 8.3 to 30.1 m below ground level (Table-3). In most part of the district the general slope of water table conforms to the topography of the area. Generally the phreatic aquifers within depth of 50m below ground level provide yields between 100 to 500 lpm. The quality of groundwater is good.

Hydrogeomorphological mapping reveals that excellent ground water prospect area in the Panchkula district is only 8.5% (Table-4).

Conclusion
The Panchkula district exhibits diverse hydrogeomorphological conditions due to its location, topography and geology. The main hydrogeomorphic units found are alluvial plain, flood plain, denudational hill, piedmont zone, intermontane valley and structural hill. Excellent to good ground water prospect zones cover about 40% area of the district, whereas rests of the area constituted by denudational and structural hills has moderate to poor and nil prospects.

The groundwater in the districts occurs under unconfined water table conditions in the upper aquifers and semi-confined to confined conditions in the deeper aquifer zones. The level of development of groundwater is still to reach its optimum level. The potential aquifers can be exploited with shallow and deep tube wells. The Piedmont zone should be considered for further exploitation of groundwater through deeper tube wells.

It is to be noted that Raipur Rani and Barwala blocks in Panchkula district show maximum exploitation of groundwater, hence its further exploitation of groundwater in these two blocks should be restricted and possibilities of recharging aquifer zones should be explored.

References

  • Drury, S.A. (1987). Image interpretation in geology. Allen and Unwin Pub., London.
  • Hydrogeology and ground water resource potential of Panchkula district (1998), CGWB, NWR-Chandigarh.
  • National Rural Drinking Water Mission methodology manual for preparation of ground water prospective zone maps, NRSA, Department of Space, Hyderabad, 1999.
  • Tood D.K. (1980), Ground Water Hydrology, John Wiley and Sons, New York.