4.2 Ajabgarh series
The Ajabgarh series of rocks comprise of
carbonacious phylite, slate, thinly bedded
quartzite, chlorite, sericite schist and
quartzitic schist. These are better aquifers
than Alwar rocks. There is a lack of primary
porosity and permeability due to metamorphism,
but secondary porosity and permeability is
found due to joints and fractures which faci
litates harbouring of the groundwaters under
watertable conditions mainly. Well in these
rocks yield discharges ranging from 3.6 to
10 cubic metres per hour.
4.3 Quaternary deposits
Recent to Sub Recent deposits of Alluvium
and loess with good primary porosity and
permeability has high recharge potential.
They form aquifers and contain potable to
brackish water. Wells tapping these depo
sits are capable of yielding good supplies,
ranging from 30 to 40 cubic metres per hours.
The yield of well varies from place to place,
but generally wells located in the vicinity
of Yamuna river and Agra canal yield more
than other wells.
5 GROUNDWATER POSSIBILITIES IN DIFFERENT
GEOMORPHIC UNITS
5.1 Structural and Denudational hills
Structural hills of hard quartzite rocks
form a runoff zone. However, some ground-
water occurs and moves through joints,
ractures and faults. Delhi quartzites with
high relief and steep slope show high runoff
zone and very poor recharge. No well has
been dug in this unit due to poor aquifer
characteristics. Near the Siva temple,
Firozpur Jhirka, one dug well in Alwar quart
zite is noticed. Depth to water is about
8 metres. It is also located in the faulted
zone of the Siva temple. A perennial spring
is also noticed close to dug well. The well
might be recharged through groundwater colle
cted in fracture zone, otherwise no dug well
has been reported.
5.2 Pediment
Owing to hardness of area, slope and very
limited weathering, pediment forms mainly
runoff zone. It possibly provides nominal
recharge surface for lower pediment zone.
The good quality water is found in this
unit.
5.3 Buried pediment
This unit consists of clay, silt and sand
with nominally weathered, jointed rocks.
beneath. It is a recharge zone. Water is
found under watertable conditions. The
thickness of deposited materials varies
from place to place. Depth to watertable
varies from 8 to 20 metres. The quality of
water ranges from potable to brackish.
5.4 Intermonatane valley fill
This unit consists of wind blown materials.
The unit is located between two ridges, so
it does not carry much groundwater weightage
in present study area.
5.5 Obstacle sand dunes and sandy loess
plain (dissec ted)
Most of the area is covered by sand. This
area is barren and intensive gaily network
has been developed indicating a high runoff
zone. The material is porous and permeable,
still owing to steep slope, there is very
poor recharge, and almost all precipitation
contributes for runoff. There is no culti
vation over this unit. Water is potable
but at places slightly brackish.
5.6 Sandy loess plain (undisserted)
Considerable area is covered by aeolian sand
which is being cultivated by well irrigation
and at some places rainfed cropping is also
practiced. Sand is fine grained, well groun
ded with high porosity and permeability.
Only local development of Kankar is found.
Depth to watertable in area ranges from
8 to 20 metres.
5.7 Alluvial plain
This unit comprises of old flood plain and
closed basin. The alluvial plain country
is composed of the clay, silt and sand. The
watertable varies from a few metres to 20
metres. In old alluvial plain salt affected
areas occur and paleochannels fills are
having shallow watertable and good recharge.
The good quality of water is found in paleo-
channel. The quality of water ranges from
potable to saline.
6 DEPTH TO WATERTABLE AND WATERTABLE
EVALUATION
The depth to watertable, in general, lies
within 8 metres below ground level in a
large part of the area; the shallowest being
0.2 metre below ground level and deepest
32.85 metres. It is evident from figure 2
that the depth to watertable is more in the
vicinity of hilly tracts. Shallow water-
table is found in a large parts of the area
east to the ridges, and west to Agra canal.
The watertable contours generally follow
the surface topography. The altitude of
watertable ranges from 179.6 to 281.5 metres
above mean sea level. In the eastern part,
hydraulic gradients are moderately steep.
The watertable slopes southwards in the
northeastern part of the area with an average
hydraulic gradient of 0.6 metres per kilo
metres. In the south western part, in the
valley between two ridges, groundwater move
ment is NNE with hydraulic gradient of the
order of 1.45 metres per km. NNE - SSW
trending ridges form a groundwater divide.
The fluctuation of watertable is of two
types, the long term and seasonal. Broadly,
the seasonal fluctuations are caused by
seasonal variation in rainfall and ground-
water draft whereas the secular variations
are mainly a result of groundwater develop
ment. During the period of June 1974 to 78
a rise in watertable has been observed in
most of the hydrographic stations of the
order 0.41 to 2.23 metres and a recession
of about 1 metre in two stations. The five
years average seasonal fluctuations in the
various blocks of the region varies from
1.2 to 2.5 metres. Considering the long
term fluctuations between 1961-63 and 1975-
76, it is seen that there is a rise in water
level in most of the part of the region
which ranges from 0.1 to 8.6 metres.