Full text: Remote sensing for resources development and environmental management (Volume 1)

Ramana Rao (1984,1985). No attempt has so 
far been made to map land use through remote 
sensing techniques in this area. 
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 
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 
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(Unpublished technical report, 1971).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 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 
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

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