160
R. Murmu and S. Murmu
The Subarnarekha basin falls in the tropical monsoon climate region with a marked
hot and dry season, with a pronounced monsoon season, and a mild winter season.
Rainfall received by the river comes during the monsoon, which spans from the
month of June to August. The season of the retreating monsoon experiences mild
rainfall and sometimes tropical cyclones that occur from September to November.
3 Model Setup
The SWAT model is a physically based distributed parameter model which has been
developed to predict runoff, erosion, sediment and nutrient transport from a catchment developed by the USDA Agricultural Research Service. In this model, prediction of runoff as well as pre and post-processing of runoff is carried out using a
number of spatially varied dataset, i.e., topography, soils, land cover, and weather. The
ArcSWAT interface package in ArcGIS was used to setup the model. The model simulation was conducted on the basis of delineation of catchment area using the Digital
Elevation Model (DEM) data, preparation of the input data using soil, slope, land
use, Hydrologic Response Unit (HRU) definition weather data definition. Finally, it
was run to obtain the output.
3.1 Watershed Delineation
For delineating the catchment area ASTER GDEM acquired from https://earthexpl
orer.usgs.gov/ with spatial resolution 30 m has been used. The watershed delineator
tab in ArcSWAT was used to define the basin and subbasins for the river under
study based on the DEM as input. At this stage, few steps were followed in which
flow direction, flow accumulation, stream definition maps were developed to obtain
subsequent stream network utilizing DEM, and finally, the outlet point was defined (at
Gopiballavpur gauging station) to for the development of the catchment. The entire
catchment with a total area of 11,394.152 km
2 has been divided into twenty-one
sub-catchments to represent its spatial variability ‘Fig. 2.’
3.1.1 Landuse Classification
Analyzing the effect of land use and land cover (LULC)practices on the hydrological
response of a watershed is important as the distribution and land cover class affect
the rate of infiltration, runoff, and thus the volume of total surface runoff at the
outlet. Image classification is done using supervised classification technique using
Landsat 8 image. The landuse are classified into five classes, i.e., Sand, Forest, River,
Reservoir, Agricultural land and Fallow land. In ‘Fig. 3,’ the classified LULC map
has been shown.
R. Murmu and S. Murmu
The Subarnarekha basin falls in the tropical monsoon climate region with a marked
hot and dry season, with a pronounced monsoon season, and a mild winter season.
Rainfall received by the river comes during the monsoon, which spans from the
month of June to August. The season of the retreating monsoon experiences mild
rainfall and sometimes tropical cyclones that occur from September to November.
3 Model Setup
The SWAT model is a physically based distributed parameter model which has been
developed to predict runoff, erosion, sediment and nutrient transport from a catchment developed by the USDA Agricultural Research Service. In this model, prediction of runoff as well as pre and post-processing of runoff is carried out using a
number of spatially varied dataset, i.e., topography, soils, land cover, and weather. The
ArcSWAT interface package in ArcGIS was used to setup the model. The model simulation was conducted on the basis of delineation of catchment area using the Digital
Elevation Model (DEM) data, preparation of the input data using soil, slope, land
use, Hydrologic Response Unit (HRU) definition weather data definition. Finally, it
was run to obtain the output.
3.1 Watershed Delineation
For delineating the catchment area ASTER GDEM acquired from https://earthexpl
orer.usgs.gov/ with spatial resolution 30 m has been used. The watershed delineator
tab in ArcSWAT was used to define the basin and subbasins for the river under
study based on the DEM as input. At this stage, few steps were followed in which
flow direction, flow accumulation, stream definition maps were developed to obtain
subsequent stream network utilizing DEM, and finally, the outlet point was defined (at
Gopiballavpur gauging station) to for the development of the catchment. The entire
catchment with a total area of 11,394.152 km
2 has been divided into twenty-one
sub-catchments to represent its spatial variability ‘Fig. 2.’
3.1.1 Landuse Classification
Analyzing the effect of land use and land cover (LULC)practices on the hydrological
response of a watershed is important as the distribution and land cover class affect
the rate of infiltration, runoff, and thus the volume of total surface runoff at the
outlet. Image classification is done using supervised classification technique using
Landsat 8 image. The landuse are classified into five classes, i.e., Sand, Forest, River,
Reservoir, Agricultural land and Fallow land. In ‘Fig. 3,’ the classified LULC map
has been shown.