For forecasting floods in the major rivers of the country, the nodal agency is the Central Water Commission (CWC) under the Ministry of Water Resources of the Government of India. CWC’s headquarters are in New Delhi with field stations located in the major interstate river systems. Flood forecasting for rivers means basically that an estimate is made of the future stages or water levels in the river at selected points along the river during flood season.
The aim is to forecast the crest and its time of occurrence at a place along the river. For this, it is necessary to have hydroiogical data (characteristics of the river basin and the flood plains) and hydro meteorological data (rainfall in the catchment area, weather forecast, current levels of water and flow along the river). The meteorological data related to weather and climate and the weather forecasts are provided by the India Meteorological Department (IMD) of Government of India to CWC who use this information, along with the hydroiogical data generated by their own organization, to formulate flood forecast.
For floods other than river floods such as flash floods, blockage of water due to inadequate drainage, forecasting takes the shape of monitoring because forecasting of such local events is not practical and the only effective method is to mount a monitoring and reporting system locally.