Khadri S.F.R*, Sachin Thakare and Pooja Surkar
In this study an attempt has been made to understand various geomorphological factors controlling the various landforms which in turn helpful in the delineation of watershed in Amravati tehsil through remote sensing and GIS techniques. The study area exposes part of Pedhi River and Kholad River which is a part of Wardha Watershed. The present investigations have helped to understand the groundwater potential as well as nature of the watershed with the help of detailed geomorphological investigations. Satellite remote sensing data as well as topographic data has been widely utilised in this study to identify the watershed and groundwater potential zones with the help of latest available techniques.
The results of the present study demonstrate the presence of various hydro geomorphological zones showing their groundwater potentialities which vary from excellent to poor. The study area covering Pedhi watershed shows excellent to good ground water quality whereas the Kholad and Kapasi watersheds show moderate to poor ground water quality. Overall, the present study demonstrates the useful ness of remote sensing and GIS techniques in the delineation of potential aquifers in the region which plays a major role in the sustainable management of water resources in the Amravati region.
Key Words: Remote Sensing, GIS, Geomorphology, Watershed, Satellite, Topography.
A watershed can be defined as the area of land that drains to a particular point along a stream. Each stream has its own watershed. Topography is the key element affecting this area of land. The boundary of a watershed is defined by the highest elevations surrounding the stream. A drop of water falling outside of the boundary will drain to another watershed (Sewickley Creek Watershed Conservation Plan, 2003). From a planning standpoint, watershed is considered the most ideal unit for analysis and management of natural resources. For optimal use of environmental resources in a region, integrated watershed development approach is still viewed by many to be the most ideal as it helps in maintaining the ecological basis of resources utilization (Sahai 1988). Geomorphology is defined as the science of landforms with an emphasis on their origin, evolution, form, and distribution across the physical landscape. The science that deals with surface features of the earth, their forms, nature, their origin and development is termed as geomorphology. DAVIS (1912) first projected the concept of geomorphic cycle. According to bauling (1950), the role of factors that are important the geomorphology are lithology, stratigraphy, climatic variation and the regional basis for the development of landforms. The use of remote sensing technology for Geomorphological studies has definitely increased its Importance due to the establishment of its direct relationship with allied disciplines, such as geology, soils, vegetation/Land use & hydrology.
Geomorphological mapping involves the identification and characterization of various landforms and structural features. The various landforms can influence a conservation area in many ways like slope gradient, elevation and aspect, affect the quantity of solar energy, water, nutrients and other materials, while the slope affect the flow of materials. Slope is also the deciding factors of intensity of disturbance, such as fire and wind, which are strongly influenced by the pressure of vegetation (Swanson et al 1988).
Amravati Tehsil basically part of Amravati city and the villages around it lying between 220 45” N to 210 20” N and 770 32” E to 780 02” E. Amravati is District place and major city in Vidharbha region. Amravati names comes from Hindu goddess “Ambadevi”, in Mahabharata epic Amravati is a capital of Vidarbha Naresh, and it is a part of Varhad (Berar).
Amravati Tehsil is bordered with Achalpur tehsil as well as Murtizapur Tehsil in North direction and Chandur Bazar Tehsil touches the boundary in east and west direction. Wardha River is naturally separate Amravati District from Wardha District. Wardha River is a major River of Vidarbha region which is join Painganga River in the boundary of Marathwada. Pohra Malkhed is protected forest area in Amravati. The average elevation is 543m from MSL.
Climate of Amravati Tehsil is hot and dry, April to June Month having extremely heat and temperature goes to 450 C as well as winter season temp goes down 110 C which shows temperature variation, Rainy season start from end of June Month to September in an average.
There are three main types of soil present in Amravati Tehsil which is-
- Deep Black Soil b) Medium Black Soil c) Shallow black Soil
Amravati Tehsil is having different types of Crop Pattern such as Cotton, Sorghum (Jawar), Green Gram (Moong), Soybean etc. but Amravati tehsil as well as whole District is famous for Orange (Citrus Spp.)
In Amravati tehsil Badnera is Major Railway Station of Central Railway. National Highway 6 is passed through the Amravati Tehsil.Fig.1 shows the location of Amravati Tehsil.
Fig. 1 Location Map of Study Area
Materials and Method:
- Toposheet Approved by Survey of India Having 1:50000 scale
- Satellite Imagery LISS data having 23.5m resolution
- ERDAS Imagine Remote sensing Software
- ARC GIS Software
Fig.2: Flowchart showing the methodology used for Watershed
- Arc GIS 10: This software has been developed by ESRI Inc. it is one of the leading software for desktop GIS and mapping. Arc GIS gives the power to visualize, explore, query, and analyze data geographically. In this project Arc GIS has been used to display raster map, digitizing different features and querying the data for finding the attributes for any feature on map. Arc GIS Spatial Analyst is a tool which helps in analysis and understanding of spatial relationships in our data. Reclassify tool has been used to reclassify different data and raster calculator has been used for overlay analysis and calculation of final results.
- Generation of contour map: Contours are polyline that connect points of equal value of elevation. The elevation points were prepared from toposheets on a scale of 1:50000 collected from Survey of India (SOI). The collected toposheets were scanned and registered with tic points and rectified. Further, the rectified maps were projected. All individual projected maps were finally merged as a single layer. The contours were digitized with an interval of 10m. The contour attribute table contains an elevation attribute for each contour polylines. The contour map was prepared using Arc Map of Arc GIS 10. Contour map is a useful surface representation because they enable to simultaneously visualize flat and steep areas, ridges, valleys in the study area.
Fig. 3: Contour Map of Amravati Tehsil
- Generation of digital elevation model (DEM): A DEM is a raster representation of a continuous surface, usually referring to the surface of the earth. The DEM is used to refer specifically to a regular grid of spot heights. It is the simplest and most common form of digital representation of topography. The Digital Elevation model for the study area was generated from the Tin.
Fig. 4: Digital Elevation Model of Amravati Tehsil
- Generation of slope map: The Slope function in Arc GIS 10 calculates the maximum rate of change between each cell and its neighbors. Every cell in the output raster has a slope value. The lower the slope value indicates the terrain is flatter and the higher the slope value, the steeper the terrain. The output slope raster was calculated in both percent of slope and degree of slope. Slope map was prepared from the DEM.
Fig. 5: Slope Map of Amravati Tehsil
- Generation of watershed: Watershed of the study area was demarcated using the software Arc GIS. Drainage pattern was taken as the input data.
Fig. 6: Drainage Map of Amravati Tehsil
Fig. 7: Water body of Amravati Tehsil
Fig. 8: Watershed of Amravati Tehsil
- Ground Potential zones map: Ground Water Potential Zones map of Amravati Tehsil Shown in fig. 9 having four different types of zone, they are Excellent, Good, Moderate and Poor. The Ground Water Potential Zone of Study area generated with the help of drainages, geomorphology and land use land cover with integration of Remote Sensing and GIS technique as well as Geology of that area plays an important role. Geomorphology of the study area having alluvial plain, Denudation Hills and Platues. During weighed overlay analysis, the ranking has been given for each individual parameter of each thematic map and weights of 25%, 35%, 30% and 10% were assigned according to their influence for Soil, Hydro-geomorphology, Land use/Land cover, and Slope themes respectively and obtained the ground water potential zones in terms of Excellent, Good, Moderate and Poor zones in the form of a GIS map.
Fig. 9: Ground Water Potential Zone of Amravati Tehsil
- Geomorphology Map: Geomorphology as a science developed much later than geology although several aspects of geomorphology are embedded in geological processes. Geomorphology deals with the genesis of relief forms of the surface of the earth’s crust. Geomorphological mapping and necessary supporting data are crucial to developing countries that are usually under severe environmental and demographic strains. Approaches and methods to map the variability of natural resources are important tools to properly guide spatial planning. In this paper a comprehensive and flexible new geomorphological combination legend that expands the possibilities of current geomorphological mapping concepts. The piece-by-piece legend forms a “geomorphological alphabet” that offers a high diversity of geomorphological information and a possibility for numerous combinations of information. This results in a scientific map that is rich in data and which is more informative than most previous maps but is based on a simple legend. The system is developed to also be used as a basis for applications in GIS.
Fig. 10: Geomorphological Map of Amravati Tehsil
Results and Discussion
Five major watersheds were identified in the area. The area occupied by the largest watershed is 167 Sq.km and it falls under the Sub-watershed category which covers around 66.01 % of the area under study, the second watershed has an area of 37 sq km and this also falls in the sub-watershed category and covers around 14.62 % of the study area, the third watershed has an area of 35 Sq.km and falls in the category of Micro-watershed occupying about 13.83 % of the study area. There are two small watersheds having an area of 5 Sq. Km. and 9 Sq. Km respectively falling in the category of Mini-watershed and covers around 4% of the study area
- DEM is the 3-D presentation of the surface derived by the interpolation of contour map. It represents x, y and z-axes in pixel size of the order 23.5 meters. The altitude or z axis ranges from 291 meters to 466 meters above sea level
- Digital slope was derived from DEM on pixel size of order 23.5 meters
- Ground water potential zones were identified on the basis of slope of the area. Five classes i.e. very good, good, moderate, poor, very poor, were identified. Most of the area comes under very good and good ground water potential zones. The area which has 1-3% slope has very good ground water potential due to nearly flat terrain, area having 3-5% slope has good ground water potential due to slightly undulating topography and some run-off, area with 5-10% slope has moderate ground water potential because these areas have relatively steep slope leading to high run-off, areas with 10-15% and 15-35% slope has poor ground water potential due to steep slope and higher run-off
Geomorphology as a science developed much later than geology although several aspects of geomorphology are embedded in geological processes. Geomorphology deals with the genesis of relief forms of the surface of the earth’s crust. Certain Natural Processes are responsible for the forms of the surface of the earth. The earth’s surface forms are primarily due to hypo gene or endogenous processes, which include diastrophism, leading to geologic structure, tectonic activity and volcanism leading to volcanic landforms.
An alluvial plain is a relatively flat landform and created by the deposition of highlands eroded due to weathering and water flow in study area. The sediment from the hills is transported to the lower plain over a long period of time. It identified on the imageries dark reddish moderate to fine texture due to agriculture activities. Alluvial deposits of the area constitute gravel, sand, silt or clay sized unconsolidated material. The area under alluvial plain cover in geomorphological map is 246 sq km.
Denudetional hills are the massive hills with resistant rock bodies that are formed due to differential erosional and weathering processes. These hills are composed of Vindhyan sediments which are fractured, jointed having no soil cover moderate to steep slope. On the satellite image, these landforms were identified by light or dark brownish with mix green color due to thick forest cover. The area under Denudetional hills cover in geomorphological map is 32 sq km.
Structural hills are representing the geologic structures such as- bedding, joint, lineaments etc. in the study area. They are located in the eastern parts of the study area having greenish and reddish tone with rough texture on the satellite image. The area under structural hills cover in geomorphological map is 3 sq km.
A flood plain is an area of land that is prone to flooding. People realize it is prone to flooding because it has flooded in the past due to a river or stream overflowing its banks. A flood plain usually is a flat area with areas of higher elevation on both sides. The area under flood plain cover in geomorphological map is 1 sq km.
A habitation Mask is an area of land that is occupied by human being. It is human settlement area. It is defined as an area of human habitation developed due to non-agricultural use and that which has a cover of buildings, transport, communication utilities in association with water, vegetation and vacant lands. The area under Habitation Mask cover in geomorphological map is 118 sq km.
A plateau is an elevated land. It is a flat topped table standing above the surrounding area. A plateau may have one or more sides with steep slopes. The area under plateau cover in geomorphological map is 458 sq km.
It is an area of impounded water, areal in extent and often with a regulated flow of water. It includes man-made reservoirs/lakes/tank/canals, besides natural lakes, rivers/streams and creeks. The area under water body cover in geomorphological map is 32 sq km.
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