Full text: Commission VI (Part B6)

  
4. DATABASE AND METHODOLOGY 
Digital data IRS 1A LISS II, October 1990, Path 29 Row 48 A1, 
Geocoded FCC (band 2,3,4) ofIRS 1B LISS II, October, 1992 and 
March, 1993 satellite imagery and panchromatic B/W aerial 
photographs, 1988 (1:50,000 scale) have been used in the above 
study. Based on monoscopic interpretation of satellite imagery, 
bytakinginto consideration various image interpretation elements 
such as color, tone, texture, size, shape, shadow and association 
etc., stereoscopic interpretation of aerial photographs and 
information extracted from field observations on depth to water 
level and water quality and digital image processing, the following 
thematic maps were prepared on 1:50,000 scale. 
* Geological map 
* Geomorphological map 
* Lineament map 
* Slope map 
* Drainage map 
* Drainage density map 
* Depth to water level map 
(Nov. 1994) 
* Water level fluctuation map 
(June to Oct. 1993) 
* EC based quality map 
All the above thematic maps were digitized by reducing these 
maps on 1:131,578 scale to fit the size of the digitizer (20 cm x 
20cm). IDRISIGIS software package was used to integrate all the 
above thematic maps. À standard grid cell size of 200X200 has 
been selected by considering a number of factors like size of 
minimum interpretable unit and appropriate format for the screen 
display. All these digitized maps were rasterized by the process 
of lineras and polyras. A rating weightage factor system has been 
developed for the integration ofthese thematic maps. A numerical 
rating system ranging between 0 to 10 have been assigned to 
various classes of individual theme maps based on the degree of 
influence of individual categories on ground water regime of the 
region. Secondaly all these thematic maps have been assigned a 
weightage factor, this is called equal wieghtage integration method 
aimed at reducing subjectivity in the analysis, however it can not 
remove subjectivity in rating/coding, completely from the analysis. 
Two composite maps one based on integration of satellite based 
information and another integrated field observation map, were 
prepared. These were further overlayed and a composite map was 
prepared. By integrating this map with EC based quality map, 
hydromorphogeological map was finally prepared showingutility 
map for ground water prospects. 
S. RESULTS AND DISCUSSION 
Hydromorphogeological map of the area is shown in map -2. 
Utility map showing ground water prospects in various zones is 
shown in map -3. Hydromorphogeological characteristics and 
ground water prospects of various geomorphic units are discussed 
below: 
5.1 HILLS 
5.11 Low structural hills: The area is traversed by two parallel 
ridges bordering the N-S Sohna valley, known as Harchandpur 
and Sohna ranges. These are composed of Alwar group of rock 
formations of Delhi super group. Lithological composition is 
20 
essentially quartzites with pegmatite veins and schist intercalations 
with subordinate bands of arsenopyrite and graphite. Five set of 
joints have been demarcated. In the vicinity of pegmatite bodies 
the quartzites are often sheared. Joints allow limited infiltration 
into them. However by and large “low structural hills" acts as a 
Zone of surface run off and is negligible from ground water point 
of view. 
5.12 Valley fills: It consists ofunconsolidated material, coarseto 
fine sand, silt and clay. Water level was observed as 6 to 12 
meters below ground level (bgl) with fresh quality. It is good from 
ground water prospects point of view. It harbours limited water 
hence dug wells/ shallow tubewells are suggested in this zone. 
5.2 PEDIMENT 
A narrow zone immediately bordering the hills is pediment, 
representing partly an undulating rocky surface sloping away 
from the hills and partly a surface with very shallow weathering 
and a thin veneer of soil. It is composed of weathered quartzites 
with gravelly soil and is found at few places in the study area. 
Water level in this zone varies from 15 to 20 metres (bgl). 
Pediments with joints or fractures yield limited extent of ground 
water. This zone is poor from ground water exploration point of 
view. 
5.3 PIEDMONT PLAIN 
This zone is constituted of both piedmont aeolian plain and 
piedmont alluvial fan plain. It is composed of coarse to fine sand, 
silt and clay and is highly porous and permeable. Dendritic 
drainage pattern observed. This is a fresh water zone with water 
level ranging from 16 to 21 metres (bgl). EC in this zone varies 
from 0-2,000 micromhos/cms. It falls under fairly moderate to 
good ground water prospective zone. 
S.4 AEOLIAN PLAINS 
Large area in western side is covered by sand of aeolian origin 
with presence of scattered sand dunes/sand mounds. The color of 
sand varies from light brown to tan/buff. Lithological composition 
is medium to fine sand with little clay. It is porous and permeable. 
There is no surface drainage in this zone, but small drains which 
originate from hill sides die out in this area, hence it is good from 
ground water recharge Point of view. Depth to water level varies 
from 17 to 27 meters. EC in this geomorphic unit varies from 0- 
2000 micromhos/cms. Average discharge of tubewells in this unit 
ranges from 150 to 350 ltrs per minute (lpm). This is good to 
moderate from ground water point of view. Moderately deep to 
deep tubewells are recommended in this area. Artificial recharge 
should be considered by constructing check dams/waterharvesting 
structures or erthen dams at suitable locations after due 
investigations. 
S.S ALLUVIAL PLAIN 
5.51 Paleochannels/channel remnants: Two paleochannels of 
probably Yamuna River have been demarcated in the area. Few 
channel remnants have also been identified. These are composed 
of coarse to medium sand with silt and clay, forming good 
aquifers. These are highly porous with water level varying from 
4-9 meters (bgl). Shallowto deep tubewells are feasible. This unit 
is excellent from ground water point of view. Pump test results 
showtubewell discharge of 632 Ipm near village Isaqi in this unit. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996 
 
	        
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