GIS: SPATIAL- TEMPORAL, DRAINAGE NETWORK & INTERCONNECTIVITY ANALYSES
Spatial analyses
Integrated approach involving remote sensing data,
spatial and temporal analyses tools [Geographical Information System (GIS)],
collateral data and conventional field survey were adopted for this purpose.
The base maps and the drainage maps were prepared using 1:50,000 scale
Survey of India (SOI, 1973) toposheets.
The thematic maps were prepared based on the visual interpretation of
IRS-1C satellite imagery, using the visual interpretation keys such as tone,
colour, texture, pattern, association, size shape, topography and drainage
The 1: 50000 Survey of India (SOI, 1973) toposheets were
used for the preparation of base maps and drainage maps giving a detailed
drainage information of the area, showing the streams and the drainage
channels. Ground verification and field validation of the thematic maps were
done by selecting the Training Sites consisting of prominent features like
water bodies, road and railway network and major settlements as ground control
points, and field visits were made to check the interpretation accuracy.
Wetland Map
Wetland map of 1973 was prepared using 1 : 50000 Survey of
India (SOI) toposheets. IRS-1C imagery of 1996 was used for 1996 wetlands map.
This was done by visually interpreting tools as tone, colour, texture, pattern,
association, size, shape, topography, drainage and analysed using Image processing
software (IDRISI) and GIS. The temporal changes in the number of water bodies
over two decades was detected by overlaying maps of 1973 and 1996.
WATER QUALITY ASSESSMENT
Exploratory field surveys and extensive literature review
were carried out to find the present status of wetlands in Bangalore and the
associated problems. This has helped in selecting the waterbodies (sample)
for further study. [Detailed investigations were carried out in seven water
bodies selected based on the type of pollution load and its location in
order to get an overall picture. Water quality of these water bodies was
assessed on monthly basis, by monitoring the physico-chemical and biological
parameters following APHA [American Public Health Association, Standard Methods
for Water and Wastewater Analysis, 1995], for about twelve months
at the inlet, towards center and outlet (subjected to avaliability of the boat).