National Remote Sensing Centre (NRSC), ISRO at Hyderabad monitors the status of all the water bodies in the country using satellite images and provides water spread area information on a fortnightly basis. Images from Indian remote sensing satellites, Resourcesat-2 and RISAT-1 are regularly processed using automated spectral and hierarchical analysis algorithm and to generate spatial water information.
This consists of all surface water features like reservoirs, tanks, lakes, ponds, rivers and streams. Due to the presence of cloud cover, the daily processed data are time-composited and fortnightly water spread information is made available through Bhuvan Geospatial Platform. (To access, visit Bhuvan Thematic Services and select “Water Bodies” under “Select Theme” option).
This water spread layer is used to generate grid-wise (grid size of 5 km x 5 km) water body fraction product for download throughBhuvan Open Data Archive (select “Programmes/Project” under Category, “National Information System for Climate and Environment Studies (NICES)” under Projects, “Terrestrial Science” under Group and “AWiFS: Water Bodies Fraction” under Product). This data is useful in hydrological modelling, drought assessment, surface water dynamics analysis, etc.
The temporal water spread information generated since 2012 is organised in a geospatial database in the form of water bodies. This data is published on Bhuvan Geo-Platform under Water Body Information System (WBIS) for visualisation and spatial query. It provides an integrated view of water-spread dynamics for more than 12,500 water bodies in the country. The geospatial tool provides:
- Fortnightly water spread area,
- Graphical representation of multi-temporal water spread (since 2012)
- Monthly scenarios for each water body.
It also provides regional water spread scenarios at river basin, river sub-basin, district, and state level.
It may be noted that due to the presence of cloud, there could be underestimation of the spread in few areas as optical images cannot penetrate cloud cover. Glacial lakes and water bodies in hilly regions of Himalayas are not part of this database.