479
Ramana Rao (1984,1985). No attempt has so
far been made to map land use through remote
sensing techniques in this area.
GEOMORPHOLOGY
The geomorphic map (Fig.2) shows the distri
bution and extent of landforms and the geo
morphic units. The different landforms and
land units identified and mapped in the area
are denudational hills, hogback ridges,
escarpments, river built plain, valley fills,
river terraces, abandoned channels, piedmont
zone, residual hills, 'V'shaped valleys and
pediments.
The hogback ridges are sharp-crested rid
ges, often serrated and the dips of the
strata are high (45° to 70°). The front
slope of the hogback is steeper than the
back slope. These ridges are made up of an
intercalated sequence of hard and soft rocks
namely quartzites or slates and schists or
phyllites respectively. Soft rocks like
shale and phyllites were denuded and formed
as valleys. Later these valleys were filled
up with unconsolidated colluvio-fluvial
material. The footslopes of hogback ridges
have a number of piedmont fans. The eastern
part of the Q study area has a number of large
fans with 3 slope and in the central and
western parts of the area are a number of
small fans with 3° to 5° slope. This varia
tion is probably due to the variation in the
rainfall distribution within the area. The
rainfall decreases from east to west. The
river built plain is found along the Cheyyeru,
Pulang Eru and Patagunjana rivers. River
built plain is a depositional plain with 0°
to 0°45' slope formed as a result of verti
cal accretion and planation of the river
deposits.
SOILS
Soils in the study area are broadly classi
fied into four types. Black cotton soil
(light - moderately deep to deep) occurs in
the narrow valley-fill area along Patagun
jana river. It is dark brown to gray in
colour, moderately deep to deep. Clay
content varies from 30 to 50 percent. The
pH value ranges from 7.0 - 8.5 and almost
normal in salt content up to 120 to 150 cm
(Unpublished technical report, 1971). Red
loamy soil is derived mostly from shales,
slates, phyllites, schists and quartzites.
It occurs in a broad valley fill area around
Rajampet under slight to moderate erosion.
The top soil is pale brown to light reddish
brown with uniformly reddish brown to dark
reddish coloured sub-soil. The surface soil
is loamy and the sub-soil layers are denser
tending to become clayey, with increase in
depth. The sub-soil has blocky to prismatic
structure. It is usually neutral in soil
reaction tending to become weakly alkaline
in unfavourable locations and are normal in
soluble salt content. Red earth is mostly
developed from granites and gneisses. It
occurs only in the northeastern part of the
study area. It has a rapid to excessive
surface drainage conducive to erosion. The
main problem is to improve moisture holding
capacity. Alluvium is exposed along all the
major streams.
LAND USE AND LAND COVER
Land use refers to "man's activities on
land which are directly related to land"
(Clawson and Stewart, 1965 in Anderson et
al, 1976). Land cover refers to "the
vegetational and artificial constructions
covering the land surface" (Burley, 1961 in
Anderson et al, 1976). The planning and
development of land requires an intimate
knowledge of land, its physical characte
ristics, present biological productivity,
capacity and limitations. Among all the
types of uses that the land is being put
to, the land utilised for agriculture
activities by man commands utmost importance.
The land use and land cover map (Fig.3) is
mainly based on Anderson's (1971) land use
classification. The land use and land cover
is classified into twelve types, viz., wet
crop land, dry crop land, land under horti
culture, grass land and shrub land, southern
tropical dry deciduous forest with red
sanders, southern tropical dry thorn forest,
roadways, railways, built up area, barren
land, broken ground - dissection and erosion,
and water bodies. The classification is
based on their location, type of vegetation
and human activity and general geomorphic
configuration. The following is a brief
description of the prominent units.
Wet crop land
Irrigation is mainly carried out using the
water from the surface tanks and wells. The
important crops are paddy, sugar cane and
banana. These fields occupy the low lying
plains of red loamy soil and black cotton
soil. In some places these crops are raised
only during the rainy season when the
surface tanks are full. During the dry sea
son the same areas are used for dry crops
like jowar, bajra, groundnut, which do not
require irrigation.
Dry crop land
The main crops under rainfed cultivation are
jowar, bajra, korra, ragi, pulses, horse-
gram, and turmeric. Mostly these crops can
be seen occupying the upstream areas of
tanks in the valley fill zone and river
built plain on red loamy, black cotton and
alluvial soils.
Land under horticulture
Lemon, orange, and mango plantations predo
minate in this category and occupy small
portions of valley-fill and fluvial plain
areas. Betel leaves are grown on the point
bars.
Grass land and shrub land
This unit is confined to certain places on
ridges and piedmont zones. The surface is
rocky with little or no soil cover. This
land has been utilised only for fuel, and
livestock grazing.
Southern tropical dry deciduous forests
with red sanders
This type of forest is confined to the
