Remote sensing and GIS techniques
have emerged as powerful tools for watershed management programmes. Watershed
management is the process of formulating and carrying out a course of action
involving manipulation of natural system of a watershed to achieve specified
objectives. This implies the proper use of land and water resources of
watershed for optimum production with minimum hazard to natural resources. The
quantitative analysis of drainage system is an important aspect of
characterization of watersheds. Morphometry is measurement and mathematical
analysis of landforms. Satellite images used for this study include Landsat 8
OLI image of 2018 year with a spatial resolution of 30m.Drainage networks and
other baseline information of the watershed were prepared from the Survey of
India top sheets on 1:50,000 scale and were further updated using satellite
data. Landsat 8 OLI data of study area co-registered to Survey of India
toposheet was used for displacement in the crust of the earth and have an
important role to play in development of drainage network of the region. The
present study is an attempt to evaluate the drainage morphometrics of Getalsud
region using Remote Sensing and GIS approach. The low values of bifurcation
ratio and drainage density suggest that the area has not been much affected by
structural disturbances. The study reveals that the different geomorphic units
in the study area i.e. Structural hills, Pediments, Valley fills, Pedi plains
formed under the influence of permeable geology, are moderate to nearly level
plains, with medium to low drainage density(<2.0)&low cumulative length
of higher order streams. Such studies can be of immense help in planning and
management of watershed.
Figure 1. Drainage map of the Study Area
Table
1. Stream orders, stream number, stream length in the study area.
Serial No
|
Stream Order
|
Stream Number
|
Total Stream Length (Km)
|
Mean Stream Length
|
Bifurcation Ratio
|
1.
|
1st order
|
131
|
101.62
|
0.77
|
-
|
2.
|
2nd order
|
40
|
56.75
|
1.41
|
3.2
|
3.
|
3rd order
|
11
|
21.15
|
1.92
|
3.6
|
4.
|
4th order
|
03
|
29.52
|
9.84
|
3.6
|
5.
|
5th order
|
01
|
12.27
|
10.05
|
3.0
|
Stream
Order (Nu)
The
stream order of Getalsud region
is presented in Table 1.The total number of stream segments is found to
decrease as the stream order increases in the basin. The study reveals that the
development of 1st order streams is maximum in the basement complex area and
minimum in the alluvial plains (Table 1). The number of 1st stream
order in a basin of a given size is dependent upon a number of factors which
include climatic, geologic and hydrologic. The trunk stream through which all
discharge of water and sediment passes is therefore the stream segment of the
highest order Getalsud region which is the trunk in the study area is of the
fifth order.
Stream Length (Lu)
The
stream length of the various stream orders in Getalsud region is presented in
Table 1. Stream length is one of the most important hydrological features of
the basin as it reveals the surface runoff characteristics. Streams of
relatively smaller lengths are characteristics of areas with larger slope and
finer textures. Streams with longer lengths are generally the characteristics
of flatter surface with low gradients. Usually, the total length of stream
segments is highest in first stream orders and decreases as the stream order
increases.
Figure
2.Harvesting structure of the Study Area
Serial no
|
Parameter
|
Calculated value
|
1.
|
Drainage density
|
0.78
|
2.
|
Stream frequency
|
0.66
|
Figure3.
LU/LC of the Study Area
The
land use land cover map of the study area shows that the area mainly consists
of waste land, fallow land .The small patches of dense vegetation & light
vegetation can be seen.
Figure
4. Aspect Map of the Study Area
The
study reveals that GIS and remote sensing can be very useful in evaluation of
various morphometrics parameters and its influence on landforms. Interpretation
of satellite images can help delineate lithological and geomorphic units. GIS
facilitates analysis of various mor phometric parameters and acts as an
effective tool in establishing relationship between drainage Morphometry and
properties of landforms. The study also reveals that DEM can useful in studying
the topography within GIS environment. Geomorphological study of an area is the
systematic study of present day landforms, related to their origin, nature, development,
geologic changes recorded by the surface features and their relationship to
other underlying structures.A particular watershed may get the top priority due to various reasons, but, often, the intensity of land degradation is taken as the basis. The assessment of the physical parameters of the land is possible by analyzing the slope, soil, geomorphology, land use; terrain parameters etc. are very much amenable to GIS analysis.
Obaidullah Ehrar, Msc (ARTD) 1st Year
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