8-Aug-2022: Flood Forecasting and Early Warning System

Forecasting system is essential to predict likely increase in water level in rivers. Central Water Commission (CWC) provides statistical methodology (gauge to gauge correlation) based short range flood forecast. Presently, flood forecasts are issued by CWC at 332 stations (133 Inflow Forecast Stations and 199 Level Forecast Stations). Annually, about 10,000 flood forecasts are issued by CWC.

CWC is currently providing near real time five-day advisory flood forecast on its web portal https://aff.india-water.gov.in/ for 20 major river basins of the country. The five day advance forecast is generated using various available rainfall data products like forecast rainfall data GFS (Global Forecast System) and WRF (Weather Research and Forecasting) provided by IMD (Indian Meteorological Department), rainfall estimates namely GsMaP (Global Satellite Mapping of Precipitation) & GPM (Global Precipitation Measurement), as a major input into the model system. The system is developed in-house using modelling software for flood forecasting which is updated every three hours for all the stations simultaneously in automatic mode during monsoon season.

CWC has also taken up the work of development of near real time Inundation Forecast for Ganga Basin through consultancy under National Hydrology Project (NHP) using High Resolution Digital Elevation Model (DEM) received from NRSC/ Survey of India / State Govt.

The data collected from field stations is transmitted from the site to the concerned Flood Forecasting Centre of CWC through wireless and/or telephone/mobile and satellite based telemetry system & VSAT. Central Water Commission maintains Wireless Stations for near real–time data communication. These wireless sets work on pre-fixed schedules for receiving the vital hydro-meteorological data immediately after its observation. Now under modernization program, satellite based Telemetry System has been installed at various stations for sensor based automatic data collection and satellite based communication. The data is transmitted to the Earth Receiving Station through Satellite and then to various Modelling Centres through VSAT Systems. The nodal officer of the dam/reservoir share reservoir related data with CWC through uploading on Water Information Management System (WIMS) or sending through e-mail/SMS/Phone/Wireless etc.

Dissemination of flood forecasts has also been modernised by having a dedicated website https://ffs.india-water.gov.in. In addition, telephone/mobile phone, fax and internet are used for dissemination of flood forecasts to user agencies. Daily Flood Situation Reports cum Advisories are shared with all stakeholders as well as general public using social media platforms.

14-Mar-2022: Flood Forecasting System

Central Water Commission (CWC) is currently formulating Five Day Advisory Flood Forecast for 20 major flood prone river basins in the country since the monsoon of year 2016. This activity has been developed in-house and utilizes global rainfall products like GPM (Global Precipitation Measurement), GsMAP (Global Satellite Mapping of Precipitation- a product of Japan Aerospace Exploration Agency) and IMD (India Meteorological Department). For formulation of flood forecasts based on these rainfall products, 1-D Mathematical Flood Forecasting Models have been developed for 20 major river basins. These advisories are shared with concerned stakeholders on a public domain GIS dashboard which can be accessed at https://120.57.99.138/.

The Development of Water Resources Information System (DWRIS) a Central Sector Scheme, has multiple components including inter-alia Hydrological Observations (which are also used for Flood Forecasting). DWRIS is a Central Sector Scheme with funds being released only to offices under CWC for establishing as well as running and maintenance of flood forecasting network in the country.

Under the National Hydrology Project (NHP), a central sector scheme with support from World Bank, the Real Time Data Acquisition System (RTDAS) and other Discharge measurement equipment are being installed to support the Flood Early Warning Systems across the country. Apart from this, some of the states facing flood issues on regional and local level are being supported for establishing Flood Forecasting Systems. These are as follows:

• Maharashtra: Real Time Stream flow Forecasting & Reservoir Operation System for Upper Krishna & Bhima River Basin.
• Damodar Valley Corporation: Developing Flood Forecasting and Inundation Model (Decision Support System) from 12 Km downstream of Durgapur Barrage up to outfall of Damodar River (Amta and Mundeshwari Rivers).
• Kerala: Establishment and Operation of Flood early warning System in flood prone areas in Periyar Basin.
• Nagaland: Development of Flood Forecasting Model in Dhansiri River.
• Punjab: Development of inflow forecasting system of Ranjit Sagar Dam and Inundation forecasting downstream of Ranji Sagar dam.
• Tripura: Development of Flood Warning System for Agartala and Kailashahar.

No information has been provided regarding establishing of the MAITRI Centers by the Water Resources Department of the State of Maharashtra.

3-Feb-2022: Challenges of Flood Forecasting

Flood Forecasting on International & Inter-state Rivers is formulated and issued by Central Water Commission (CWC) using statistical methods for short range forecasting and mathematical modelling for five day’s advance flood advisory. The main challenge being faced in flood forecasting is to accurately forecast the impending flood sufficiently in advance with high level of accuracy. Mathematical modelling based flood advisory although provide sufficient lead time, its accuracy is dependent on accuracy of weather(rainfall) forecasts. The growing incidents of high intensity rainfall in shorter duration due to likely impact of climate change poses another challenge for flood forecasting.

There is a continuous effort for improvement of Flood Forecasting using all the latest technology including space technology tools, Geographical Information System (GIS), web based applications, etc. Following steps have been taken to improve the Flood forecasting system in the country.

• Expansion of Flood Forecasting Network: CWC flood forecasting network has been expanded to 331 Flood Forecast Stations(199 Level Forecast for Villages/Town on the bank of the rivers and 132Inflow Forecast Stations for Dams and Barrages) covering 23 States &2 UTs in 20 river basins for taking proper mitigation measures by respective State Governments. In the State of Andhra Pradesh, there are 13 level forecasting stations and 10 in flow forecasting stations.
• Modernization of Flood Forecast Formulation: Flood forecasting is issued up to 5 days in advance for major river basins across the country including the State of Andhra Pradesh. The same is updated every three hours and is available online (https://120.57.99.138/index.php).
• Modernization in dissemination of flood forecasts: Dissemination of flood forecasts has also been modernized through a dedicated website. Daily Flood Situation Report cum Advisory is shared with all stakeholders as well as general public using social media platforms.

Bilateral agreements with upper riparian countries Nepal, Bhutan &China have been made for data sharing.

Common data platform, Water Information Management System(WIMS), under National Water Informatics Centre (NWIC), has been created to ensure seamless data flow from States and CWC for modelling work. In addition, arrangements for seamless data flow from agencies like INCOIS, NASA, JAXA, etc. have also been made.

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