Government plans digital atlas to issue flood warnings to residents

The Union government is preparing a digital atlas with maps of flood-prone areas that will give real-time information and warnings about any rise in the water level of local rivers and streams that can inundate crops and homes, officials in the water resources ministry said.

According to the officials, who didn’t want to be identified, this project of the Central Water Commission with the help of the Survey of India and the National Remote Sensing Centre (NRSC) of the Indian Space Research Organisation will help local administrations reduce the loss of life and damage to property during floods.

Countries such as the United States are already using digital flood maps successfully. But the flood warning system in India is based on water-level forecasting, which tries to predict how much the level will rise by calculating the flow of water into dams and reservoirs, the officials said.

“For the first time the government will predict inundation areas at different levels of water. For example, which areas will be affected when a river’s water is a foot above the danger mark, or two feet above,” a senior ministry official said. “An evacuation plan can be made accordingly.”

The atlas, officially named “inundation flood advisory”, will be most useful in Assam where the Brahmaputra swells every monsoon and submerges large tracts of land, including the Kaziranga national park, the Majuli river island and scores of villages close to its banks.

In a pilot project, the government has mapped the Brahmaputra basin from eastern Assam’s Dibrugarh district to the international border from where the river enters Bangladesh to drain out into the Bay of Bengal. The high-resolution mapping with satellite imagery includes areas within a 2km kilometer radius of the river’s banks.

According to data released by the Assam State Disaster Management Authority, the state recorded its worst floods in four years in 2017 as the Brahmaputra and its tributaries breached their banks and inundated about 2,500 villages, displacing more than 1.8 million people.

The water resources ministry’s atlas project will help the state administration work with communities to protect lives — human and livestock — and property by providing tools and information to help them understand flood risks and make cost-effective mitigation decisions, the officials said.

The ministry is also planning to issue similar flood atlases for all the 20 river basins in the country by 2020. According to the officials, this will be an important step as many regions, other than the Northeast, have struggled with floods — such as flooding by the Jhelum in Srinagar and the Koshi in Bihar.

The maps for the Brahmaputra basin have been developed using 30 years of hydrological data, information on the frequency of floods, and highest recorded flooding in a particular area. The ministry has mapped at least 50 scenarios when the river, one of the mightiest in Asia, could flood its riparian areas.