A watershed is a hydrologic unit that is often used for the management and planning of natural resources. Watershed terminology; basin, sub-basin, watershed and sub-watershed are being used inconsistently due to the lack of any reference to define their extent in Pakistan.
GIS Laboratory of WWF-Pakistan is in process of building a comprehensive watershed and drainage network database using high resolution DEM derived from ASTER satellite images under the Pakistan Wetlands Programme. The aim is to support the conservation of wetlands and associated important biodiversity. The automated delineation of watershed boundaries from DEMs is recognized as a viable alternative to conventional manual methods. Automated Watershed delineation process includes fill DEM, flow direction computation, flow accumulation, derivation of stream network and delineation of watershed boundaries.
Three basins were delineated using 1km spatial resolution USGS DEM. 46 sub basins were delineated using 500m USGS DEM. Each sub basin further processed on 90 m spatial resolution USGS DEM to delineate watershed.
Each watershed further processed to delineate sub watershed for this 30m spatial resolution ASTER based are used. 290 watersheds were delineated and 280 out of 290 watersheds have been compiled to delineate their corresponding sub watershed and ancillary data are being attached with the drainage network. On completion of this exercise, the database will serve as a long-term decision making tool in watershed related activated.
Qamer, F. M., R. Saleem, N. Hussain & S. M. Raza (2008): Multi-scale watershed database of Pakistan, 10th International Symposium on High Mountain Remote Sensing Cartography (HMRSC X), September 8-11, 2008 Katkmandu, Nepal. http://menris.icimod.net/HMRSC-X/index.html