Watershed Delineation - a watershed as an enormous bowl. As water falls onto the bowl’s rim, it either flows down the inside of the bowl or down the outside of the bowl. The rim of the bowl or the watershed boundary is sometimes referred to as the ridgeline or watershed divide. This ridge line separates one watershed from
another.
Topographic maps created by the United States Geological Survey can help you to determine a watershed’s boundaries.
Land use and land cover map (LULC Mapping) -
Land cover indicates the physical land type such as forest or open water whereas land use documents how people are using the land. … Land cover maps provide information to help managers best understand the current landscape. To see change over time, land cover maps for several different years are needed.
1. Preparation of landuse/landcover map
using RS and GIS techniques
Mentor :
Dr. CHANDER PRAKASH
Prepared by:
ARUN KUMAR (17142)
NITISH THAKUR (17137)
KAPIL THAKUR (17141)
NEERAJ KUMAR (17190)
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2. • Land use/cover are two separate terminologies which are often used
interchangeably.
• Land cover refers to the physical characteristics of earth’s surface
(vegetation, water, soil and other physical features of the land, including
those created by human activities e.g., settlements.
• Land-use refers to the way in which land has been used by humans.
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Introductions
3. Objective
• DEM-Based stream and watershed Delineation.
• Visually interpreting the satellite data to map different categories of
land use/ land cover (LULC) of delineated watershed.
• Change assessment of watershed using remote sensing and GIS and
understanding the impact on the ecosystem .
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4. Study Area
UPPER BEAS WATERSHED
Kullu, Himachal Pradesh.
Kullu
Beas river rises in the Himalayas in central
Himachal Pradesh.
Outlet point of watershed –
• Location - Bhunter
• Coordinates –
Latitude - 31°53'44.06"N
Longitude - 77° 8'31.31"E
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5. ASTER DEM -
ASTER provides high-resolution images of
the planet Earth in 14 different bands of
the electromagnetic spectrum, ranging
from visible to thermal infrared light.
The resolution of images ranges between 15
and 90 meters. ASTER data are used to
create detailed maps of surface temperature
of land, emissivity, reflectance, and
elevation.
ASTER GDEM V3 From NASA Earth-data
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DATASETS AND SOFTWARE USED:
6. LANDSAT-8 SATELLITE
DATA -
The Landsat 8 satellite payload consists of
two science instruments—the Operational
Land Imager (OLI) and the Thermal Infrared
Sensor (TIRS). These two sensors provide
seasonal coverage of the global landmass at
a spatial resolution of 30 meters (visible,
NIR, SWIR); 100 meters (thermal); and 15
meters (panchromatic).
Landsat-8 Satellite data From USGS earth-explorer
DATASETS AND SOFTWARE USED:
7. Satellite Date of Generation Path-Row Sensor Band Spatial Resolution
Landsat 8 2020-10-14 147-38 Operational Land Imager
(OLI)
Band 1 - Coastal /
Aerosol
30 m
Band 2 - Blue 30 m
Band 3 - Green 30 m
Band 4 - Red 30 m
Band 5 - Near Infrared 30 m
Band 6 - Short
Wavelength Infrared
30 m
Band 7 - Short
Wavelength Infrared
30 m
Band 8 - Panchromatic 15 m
Thermal Infrared Sensor
(TIRS)
Band 10 - Long
Wavelength Infrared
100 m
Band 11 - Long
Wavelength Infrared
100 m
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The Landsat 8 OLI/TIRS C1 Level-1 satellite image captured on 2020-10-14 is used. The images were downloaded
from United States Geological Survey (USGS,https://earthexplorer.usgs.gov/) earth explorer.
DATASETS AND SOFTWARE USED:
8. Software Used -
The following software were used for satellite data processing and GIS
analysis-
ERDAS Imagine for Pre-processing.
ArcGIS 10.2 for database creation, analysis and map composition.
Hec-GeoHMS ArcGIS extension tool is used for watershed delineation and
catchment characteristics.
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DATASETS AND SOFTWARE USED:
9. Digital Elevation Model (DEM) based Hydro processing and Watershed delineation are estimated by using the HEC-GeoHMS tools
of Arc GIS Software.
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METHODOLOGY :
Fig. Flow chart for Watershed delineation.
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Various steps involved in the Preprocessing :
• Fill sinks: Fill sinks operation removes local depression from a DEM by replacing
the local depressions by flat areas in the output DEM.
• Flow Direction : Flow Direction grid, contains cells with only the numerical values
dictated by the 8-direction pour point model.
PREPROCESSING
• Flow Accumulation: It is used to determine the ultimate flow path of every
cell on the landscape grid.
• Stream Definition and segmentation : With a flow accumulation grid, streams
may be defined through the use of a threshold flow accumulation value.
• Catchment Polygon Processing: The function of catchment polygon processing
is to convert a catchment grid into a catchment polygon feature.
• Drainage Line Processing: Drainage Line Processing converts the input Stream
Link grid into a Drainage Line feature class.
Fig. HEC-GeoHMS tool bar.
WATERSHED DELINEATION
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The values represent flow in particular direction i.e.
1 – East, 2 – South East, 4 – South, 8 – South West,
16 – West, 32 – North West, 64 – North and 128 –
North East.
For ASTER DEM, the maximum flow is in the
Southwest (SW) direction, whereas the minimum flow
is in the North (N) direction.
Flow Direction Map of Beas Watershed
WATERSHED DELINEATION
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Fig. Process from the determination of flow direction to flow pattern.
WATERSHED DELINEATION
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Start New Project:
Go to start new project and enter the project name. Specify the
outlet point of the basin model by using ‘Add Project Points’ tool.
Generate Project:
Generate the project by using the method of generating as
Original stream definition. Watershed is delineated and project
setup is completed.
PROJECT SETUP
WATERSHED DELINEATION
Fig. Project Setup in HEC-GeoHMS
15. Flow Chart for making land use/land cover map (LULC)
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LULC MAPPING :
16. • For image Pre-processing and performing supervised classification of the satellite imageries,
mosaicking of data tiles is performed initially.
• For Image Enhancement, several corrections and layer stacking of satellite imageries are done to
convert multiple bands into a single layer.
• Resultant shapefile of watershed area produced through watershed delineation process was used
to clip the study area from the imageries using ArcGIS.
• These clipped images are then re-projected to Universal Transverse Mercator zone 43N and
resampled, if needed.
• FCC of the study area was also generated using band 5, 3 & 4.
R = 5 (NIR band)
G = 3 (red band)
B = 4 (green band)
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LULC MAPPING :
Image Pre-processing :
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LULC MAPPING :
LULC Mapping:
• Visual image interpretation technique of classification was applied in the study
• This Comprises of the following six major steps-
- Selection and acquisition of data
- Pre-field interpretation
- Ground data collection and verification
- Post-field interpretation and modification
- Computation of area
- Final cartographic map preparation and reproduction.
• Then all satellite data were studied by assigning per-pixel signatures. The whole watershed is
differentiated into five classes- Forest, vegetation, bare land, water bodies and snow.
• The maximum likelihood algorithm is used for supervised classification of the imagery.
18. Image interpretation key for LULC classification -
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• A final interpretation key for the various classes was
prepared using spectral characteristics of classes and
field knowledge.
• Red in false color composite image indicates the
density of the vegetation.
• Water bodies were appeared in dark blue or light blue
tone with smooth texture
• Patches of light red tones represented vegetation.
Tone Texture Shape Spectral
Signature
Description
Dark red
to light
red
Rough Irregular Tree cover (forest
canopy density >40%)
Light Red Smooth Irregular Tree cover (forest
canopy density 10-
40%)
Light red or
pinkish red
Coarse Varying Bushy vegetation with
shrubs or scattered
trees (forest canopy
density <10%)
Pinkish red to
light green
Medium
Smooth
Irregular Scattered
trees/shrubs with
exposed ground
surface; canopy
density <10%.
Pinkish or
light green
or light
blue or
light cyan
Medium
Smooth
Regular Crops/ current
fallow Lands,
surrounded by small
to medium size
settlements.
Cyan Rough Irregular/
regular
Urban as well rural
(Maximum rural)
Dark blue or
light blue
Smooth Irregular/
Linear
River, stream and
pond
LULC MAPPING :
20. Results
• The visual interpretation of the satellite data with
the ground truth was used to map different
categories of land use/ land cover (LULC) map of
UPPER BEAS WATERSHED.
• Five categories of LULC were classified which
include forest(open forest, dense forest and
degraded forest), vegetation, snow, other land use
(agriculture, settlement) and water bodies. Brief
descriptions of different categories of land use/ land
cover are given further
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Results
• Area statistics of different categories of land
use/ land cover is also given in table.
• Pie chart shows distribution of different
categories of land use/land cover.
• It can be concluded that the bare land (including
settlements) and Forest land have the highest
percentage of the total area covered in the study
area of upper Beas watershed.
22. • For many planning activities accurate and current information on land use and land cover is required.
• Visual interpretation method allows the most detailed differentiation of structures and objects which is
advantageous in detecting spatial patterns and in drafting precise boundaries around relatively
homogenous area.
• We can further use this knowledge to assess the LULC scenario and assessment by applying the
methodology on maps of past years and deriving data will along with land use change assessment table
for those years.
• Further for comprehensive study certain figures like temporal pattern and relative change in land will be
drawn and a cross tabulationa i.e. two-way cross-matrix containing different combinations of ‘‘from–to’’
change classes will be formed on pixel-by-pixel basis using in order to determine the quantity of
conversions from one land cover to other land cover category within the time frame.
• At last accuracy assessment will be done by site visiting or using google earth pro.
Discussion
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