Study projects increase in heavy rainfall intensity over Western Himalayas, stresses upon need for long-term mitigation strategies

Vijay Mohan

Chandigarh, November 5

Exploring new possible hotspot regions for future urban flooding due to increasing heavy rainfall patterns over different Indian River basins, a study has projected an increase in heavy rainfall intensity over the Indus and Upper Ganga basins in the Western Himalayas as well as intensification of severe droughts.

The significant changes in the frequency of hydro-climate extreme events may have a considerable impact on agriculture, heath and other socio-economic conditions of the society, the study states, while stressing upon the need for long-term climate adaptation and mitigation strategies, including water and emergency services policies, to minimise risk due to extremes in the basins.

Research undertaken by experts at the Mahamana Centre of Excellence in Climate Change Research at Banaras Hindu University used high-resolution simulated precipitation experiments to examine the future hydro-climate extremes over the different river basins.

The study, supported under the Climate Change Program of the Department of Science and Technology, projected a 14.3 percent increase in heavy rainfall intensity over the Indus and Upper Ganga Indus basins as well as intense precipitation over the Western Ghats and Northeast river basins.

According to the Ministry of Science and Technology, in the past few decades the increased frequency of hydro-climate extreme events over the Indian River basins due to global warming has led to a significant rise in flood-related disasters, mortality rates and economic losses, ultimately affecting the gross domestic product.

In this context, it becomes exceedingly essential to examine the future hydro-climate extremes and identify hotspot regions that are most susceptible to hydro-climate extremes.

In many river basins, extreme rainfall events are projected to increase and intensify throughout the 21st century, with greater increases after 2040.

They are projected to reach unprecedented levels by the end of the century in the absence of strong mitigation measures such as achieving the Paris Agreement targets to limit global warming to 1.5 and 2.0 degree Celsius, the researcher said.

Global warming has increased rapidly since the mid-20th century due to enhancement of greenhouse gas emissions, resulting in more hydro-meteorological hazards, which account for more than 90 percent of worldwide catastrophes and 43 percent of floods, the study observed.

At the end of the 21st century, Indian River basins will have a warmer and wetter climate that will result in variability in the hydro-climate extremes, especially during the monsoon season over the Indian sub-continent, the study said.

The continuous precipitation and temperature changes cause frequent floods in South Asia and ultimately affect food security. India is one of the world’s most vulnerable countries to hydro-climatic extremes such as droughts and floods, which affect the agricultural production of the nation, the study observed.