If there is going to be a flood, you might know two weeks in advance. 24 hours’ notice is better. | Mint

In view of the massive devastation caused by extreme climate events like flash floods in the country, the Central Government is working on a plan to upgrade the warning system to minimise loss of life and property.

The Water Resources Department is planning to leverage its technical arm, the Central Water Commission (CWC), to issue warnings about potential floods a fortnight in advance instead of the present practice of doing so 24 hours in advance, two officials said.

According to data from the Centre for Disaster Epidemiology Research, India faces a total loss of $56 billion due to weather-related disasters between 2019 and 2023, a quarter of the $230 billion losses suffered by Asia Pacific countries.

Moreover, according to the National Flood Commission, India is the most flood-affected country in the world after Bangladesh, and one-fifth of the global deaths due to floods occur in India.

One reason for this is that about 75% of total Indian rainfall is concentrated during the southwest monsoon months of June to September, causing massive river overflows and widespread flooding.

This is where the water resources department’s plans will come in. It proposes to use the CWC’s hydrological observation network of 1,543 stations, including 340 flood forecasting stations, and the India Meteorological Department’s 5,000-6,000 rain gauges to track the flow and levels of rivers and streams to provide more advance warning of floods, rather than relying solely on rainfall forecasts.

This is where the Water Resources Department’s plan comes in. It proposes to use the CWC’s 1,500 surface water monitoring observatory systems and the India Meteorological Department’s 5,000-6,000 rain gauges to monitor the flow and levels of rivers and streams, so that flood warnings can be given well in advance, rather than relying solely on rainfall forecasts.

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“At present, we issue flood warnings 24 hours in advance. Now the plan is to extend it to 7-15 days in advance,” said one of the officials. “If you are issuing advisories 24 hours in advance, the administration doesn’t have much time to work. But if it is issued seven days in advance, they can prepare better and save lives.”

The official said that initially the advisory will be issued 3-7 days before the expected flood and gradually it will be increased to 15 days.

The spokesperson and secretary of the Water Resources Department did not give any reply to this. Mints Questions were asked via email on Thursday.

New workbook for flood warning

In many countries the development of flood forecasting and warning systems is an essential element in regional and national flood preparedness strategies.

According to a report by the Assam State Disaster Management Authority, this generally involves risk assessment in terms of the probability of flood occurrence and vulnerability assessment in terms of the damage caused by floods, and hence estimating the economic savings resulting from flood reduction.

According to the National Flood Commission, about 40 million hectares of land in India is affected by floods and on an average 18.6 million hectares of land is affected every year.

“Flood forecasting means understanding which areas may get inundated, which is different from knowing how much rainfall will occur, as there is no correlation between rainfall and flood forecasting,” said the second official cited above.

“Suppose it is raining in Maharashtra and the state’s river passes through Karnataka. Heavy rains in Maharashtra can lead to increased water flow in Karnataka even if there is no rain or clouds in Karnataka. These are the things that usually cause a lot of flood problems… IMD cannot predict this as it gives area-wise forecast,” the official said.

Another approach involves assessing the water-carrying capacity of the river and determining when its water will overflow the embankments.

The second official said, “You should understand the natural path of the flow of river water…suppose there is rain on the Yamuna side in Haryana, there may be a possibility of increase in the flow in Yamuna river. (But) it is difficult to estimate right now how much rain has occurred and how much the flow will increase.”

“We will keep a close watch on rivers and streams and issue advisories to the states… The Central Water Resources Department will communicate the information to the CWC along with technical details such as water flow, level, volume of inflow.”

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Although the IMD will not be directly involved, the Jal Shakti Ministry will monitor the rainfall forecast.

“The Centre and state governments have several observatories for surface water flow. Through those observatories we keep getting information about the river flow and based on the increase or decrease in the flow, we can predict the flood situation,” the first official said.

An important tool for long-term vision

A key tool in advance flood warnings will be CWC’s Extended Hydrological Forecast or EHP, a forecasting system to predict monthly or seasonal stream or river flow patterns in the long term.

Currently, CWC’s EHP project covers three major basins of India—Yamuna in the north, Cauvery in the south and Narmada in the west. Forecasts are prepared at four major locations in each basin using a four-week horizon.

Forecasting river or stream flows several weeks out offers numerous benefits for improving water resources planning for flood mitigation, including reservoir pre-positioning, drought planning for shortages, and optimal power utilization.

Also Read | Heatwaves will be more destructive than floods in future, say experts; will have greater impact on economic growth