In: Wagner W., Székely. B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B
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soil texture and were derived using soil hydraulic properties
index defined in VIC model documentation.
a. Landuse/Landcover Map of 1972
b. Landuse/Landcover Map of 1985
c. Landuse/Landcover Map of 2003
Fig. 2 Landuse/landuse Map of 1972, 1985 & 2003
Table l.LULC statistics of 1972,1985 & 2003
W#» îawS*
ÎH)
DF Al^M D**4
SDttrr
{Hi
i*2
m.
»72
1.16
27.23
1196
5406
a os
415
134
1*85
1 19
26 64
10.92
5641
0.22
383
135
:ooj
162
23.52
996
5&63
0.31
3.51
144
The vegetation parameter file describes the vegetative
composition of each grid cell, and uses the same grid cell
numbering as the soil file (latitudes and longitudes are not
included in the file). This file cross-indexes each vegetation
class (from any land-cover classification scheme) to the classes
listed in the vegetation library. To prepare this file, landuse map
was overlaid on the grid map and the no. of vegetation classes
as well as fraction of grid covered by those classes was
extracted. A small code in C language was used to read this
information from crossed map and arrange it in the format
specified by the model. Root depths for landcover types were
accepted as recommended by Canadell et. al. (1996). It was
assumed that the specified root zone contains all of the roots of
a landcover type. For the selected land cover classification of
the study area, a vegetation library file was set up. This
describes the static (varying by month, but the same values
year-to-year) parameters associated with each land cover class.
LAI defines an important structural property of a plant canopy
as the one sided leaf area per unit ground area. For derivation of
LAI, MODIS LAI maps (MOD 15A02 product) were
downloaded from NASA’s GSFC website (www.modis-
land.gsfc.nasa.gov). For each landuse class, sufficient number
of cloud free points were chosen and their LAI profile on the
stacked image was drawn. An average monthly value of those
points was taken as the LAI value in each month for that
landuse class. Albedo was also derived from MODIS BRDF/
Albedo product in the same way. Other variables like roughness
length, displacement height, overstory, architectural resistance,
minimum stomatal resistance were derived from LDAS 8 th
database (http://ldas.gsfc.nasa.gov/LDAS8th/MAPPED.VEG/
web. veg.monthly.table.html) and MM5 terrain dataset.
The Meteorological forcing file contains meteorological
variables required to force the VIC model like daily
precipitation, daily maximum and minimum air temperature.
Forcing data files play big role in the model input to produce all
the outputs in both water balance and full energy balance modes
of the model. Accurate streamflow simulation requires forcing
input of high accuracy as it is the most influential variable
generating runoff and driving hydrological cycle. Precipitation
input was prepared using India Meteorological Department’s
1°X1° gridded rainfall dataset. Daily rainfall values for each 1
degree grid falling in the basin were extracted for 365 days in
the year 2003. Rainfall grids were then overlaid with the basin
grids to extract precipitation in each basin grid. VIC model
requires one forcing file for each grid having 365 rows and 3
columns in ASCII format. Temperature data from NCDC
(National Climatic Data Centre, NOAA) is available for some
selected stations in the study area. This point temperature data
was used to derive maximum and minimum temperature of each
basin grid using nearest neigbour and lapse rate method since it
is assumed that temperature varies with the altitude. The
following relation was applied in MS Excel spreadsheet:
T grid — Tnearest point + 5.5/1000*(elevation near est point - grid
elevation) (1)
A Global control file where the necessary information to specify
various user preferences and parameters was prepared. It
contains information like N-layers, Time step, start time, end
time, Wind H, snow temp, rain temp., Location of the input
output files, modes which are to be activated etc. The VIC 4.0.5
was compiled using gcc complier on Linux operating system.
The code was compiled using the make file included in the
archive, by typing 'make'. The compiled code creates an
executable entitled 'vicNl'. To begin running the model, ‘vicNl -
g (global control file name)' was written at the command
prompt. Global control parameters were modified according to
the input characteristics and to activate the ware balance. In
addition to that input and output path were specified. VIC
source code was executed in the LINUX environment to
generate the flux files for each basin grid. These flux files