Geomorphologic & land use planning for Danda watershed
Generation of thematic maps
Hydro-geomorphology Map Streams:
Drainage information for
this map has been derived from SOI toposheet and IRS-1C PAN data. The drainage
pattern present in SOI topographic sheet was digitised and drainage lines were
superimposed on IRS-1C PAN digital data. Digitised drainage pattern was compared
with satellite observed drainage pattern and a corrected drainage map was
finally prepared. In this watershed, various streams forming a dendritic pattern
are present. The streams are seasonal in nature and remain dry in non-rainy
seasons. Small amount of water is available only in the downstream portion of
the main stream. This map is useful for site location for harvesting of surface
water and for prioritising the watershed development.
Digital Elevation Map
The contour map and spot height map
of the area were merged together and a composite map having information about
contours as well as spot height was formed. This combined map was further
interpolated at 6-metre pixel resolution using map interpolation function
available in Integrated Land and Water Information System (ILWIS) to generate a
DEM of the area. This DEM was further checked for flats and pits present in it.
Since the area lies in steep mountainous terrain, only few flats and pits were
observed in the DEM. These flats and pits were then removed using iterative map
calculation functions of ILWIS and final DEM was generated. Removal of flats and
pits in a DEM is necessary to maintain continuity of water to the catchment
outlet from any point inside the catchment. This DEM is then used to delineate
watershed boundary using eight-direction pour point algorithm. The study area
shows the continuous increase of elevation from east to west. The DEM was
further analysed to generate slope map of the watershed. The slope map is
helpful in prioritising areas for development measures like engineering, land
suitability etc. From the slope map of the area it can be seen that most of the
watershed area falls under slope categories from 25-100%.