4.3 Vegetation Parameters and Vegetation Library File
The vegetation parameter and vegetation library files were
prepared from global land cover classification map generated by
The University of Maryland Department (UMD) of Geography
at a 1 km nominal spatial resolution (Hansen et al., 1998; 2000).
The vegetation parameter file defines the number of vegetation
types in each grid cell, along with their fractional coverage, root
depth and its fraction. The vegetation library file defines the
different landcover types allowed in the simulation and
corresponding influencing parameters namely architectural
resistance; minimum stomatal resistance; leaf-area index:
shortwave albedo; vegetation roughness length and
displacement height; trunk ratio; and height at wind speed is
measured. In this file, a flag has to be assigned to indicate
whether or not the current vegetation type has an overstory. The
values of these parameters correspond to each LULC class is
available in LDAS 8" database and MMS Terrain dataset
(http://1das.gsfc.nasa.gov/nldas/NLDASmapveg.php).
4.4 Global Parameter File
This is the main input file of VIC model which sets simulation
options, such as start/end dates and modes of operation;
compiling the locations of the above prepared input files and
directory which will store output files.
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5. RESULTS AND DISCUSSION
The hydrological simulation of the entire India has been carried
out using VIC model at 25 x 25 km grid. Initial run was carried
out for the base year 1995, which was normal rainfall year. It
was found that the estimated runoff is in close agreement as per
Indian conditions. The perfect water balance resulted for entire
landmass of India in the base year, provided impetus to study
the impact of climate/land cover change by developing various
scenarios.
The set up VIC hydrological model was run for modified
meteorological forcing files based on rainfall and temperature
increase as per scenarios developed. It was found that runoff
increase manifold with increase in overall rainfall percentage.
However, increase in temperature, which is mainly attributed
due to urban sprawl, reduces the runoff generation slightly. The
time series of estimated runoff for each scenario is presented in
Figure 4. A table of summary of analysis of each scenario is
given in Table 2. It can easily be noticed that increase in
rainfall, increase runoff manifold, whereas, increase in
temperature reduces runoff slightly.
Simultaneously, an analysis to study the effect of climate
change on evapotranspiration (ET) for the developed scenarios
has also been carried out. The summary of results is presented
in Table 3. It can be seen that ET is showing increasing trend in
both the cases.
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