Flood Forecasting and Inundation Mapping in the Mahanadi River Basin: A Collaborative Effort between India and the United States S.K. Sengupta 1 , J.D. Bales 2 , R. Jubach 3 , A.C. Scott 4 , and M.D. Kane 5 1 S.K. Sengupta: Central Water Commission, Plot No. A/13&14, Mahanadi Bhawan Bhoi Nagar, Bhubaneswar, Orissa, India, 751022; email: senguptask@yahoo.co.in ; phone: 0674-2545536; fax: 0674- 2545537. 2 J.D. Bales: U.S. Geological Survey, 3916 Sunset Ridge Road, Raleigh, NC, USA 27607; email: jdbales@usgs.gov ; phone: 919-571-4048; fax: 919-571-4041 (corresponding author). 3 R. Jubach: Hydrologic Research Center, 12780 High Bluff Drive, Suite 250, San Diego, CA USA 92130-2069; email: rjubach@hrc-lab.org ; phone: 858-794-2726; fax: 858-792-2519. 4 A.C. Scott: University of Arizona, Tucson, AZ, USA, 85719; email: cacsott@eamil.arizona.edu ; phone: 520-626-4393. 5 M.D. Kane, Riverside Technology, 2290 East Prospect Road, Suite 1, Fort Collins, CO, USA 80525-9768; email mdk@riverside.com ; phone: 970-484-7573. ABSTRACT Through a collaborative effort of several governmental agencies in India and the United States, a flood-forecasting and flood-inundation mapping system is being implemented for the flood-prone Mahanadi River basin on the east coast of India. The National Weather Service River Forecast System (NWSRFS) is being implemented and calibrated using hydrologic records for the Mahanadi basin. Central Water Commission (CWC) engineers in India are receiving training on the implementation, initialization, operation and calibration of the NWSRFS. Data-collection and telemetry are being enhanced through the efforts of Indian agencies. Flood-inundation maps are being developed through the collection of detailed topographic data and application of two-dimensional steady-flow models. These combined efforts will reduce the vulnerability of citizens in the Mahanadi River basin to floods, improve warning capabilities of the CWC, and increase long-term collaboration between Indian and American hydrologists and meteorologists. INTRODUCTION Approximately 16 percent of the world’s population lives in India on about 2.45 percent of the earth’s land. The country is subject to a variety of natural hazards, including droughts, flash floods, widespread flooding from monsoonal rains, severe thunderstorms, cyclones, tsunamis, landslides, and earthquakes. In 2003, the Government of India (GOI) and the United States Agency for International Development (USAID) initiated the Disaster Management Support (DMS) project as a collaborative effort to reduce the vulnerability of the Indian population to a variety of natural hazards. The DMS project includes implementation of a flood-forecasting and flood-inundation mapping system for the Mahanadi River basin as a demonstration 1