Increase in rainfall patterns in Indian river will increase floods in cities: Study

A recent study conducted by researchers at Banaras Hindu University (BHU) has raised concerns about the future of agriculture in the low-lying areas of the Ganga basin. The study predicts a potential drought in the near future due to a decrease in average rainfall. The average monthly rainfall in this region may reduce significantly by seven to 11 millimeters per day.

The Western Ghats and Northeast river basins will likely see an increase in the frequency of extreme rainfall, while projections indicate an increase in heavy rainfall intensity over the Upper Ganga and Indus basins. The study identified potential new hotspot regions for future urban flooding due to the increasing patterns of heavy rainfall over different Indian River Basins.

Over the past few decades, global warming has increased the frequency of hydroclimate extreme events over the Indian River Basins (IRBs), leading to a significant rise in flood-related disasters, mortality rates, and economic losses, that ultimately affect the gross domestic product.

Examining the future hydroclimate extremes and identifying hotspot regions over the Indian River Basins (IRBs) that are most susceptible to hydroclimate extremes becomes exceedingly essential. This examination and identification can prioritize urgent policy interventions, mitigation, and adaptation strategies.

Ganga Basin faces drought, urban floods

The research indicates that the increasing temperature and decreasing rainfall will not only affect the yield but will also affect the sweetness of sugarcane, a major crop sown in the Ganga river valley.

The study also identifies new potential urban areas where there may be a risk of floods in the future due to continuous heavy rains. Experts estimate that these changes in the rain pattern will cause serious floods in the Western Ghats as well as in metropolitan cities like Mumbai and Pune.

The risk of floods will also increase in Hyderabad, Bengaluru, and Chennai due to heavy rains in monsoon. Urban planners and policymakers will need to take proactive steps to deal with this emerging threat.

The research, led by Prof. R. K. Mall from Banaras Hindu University (BHU), used high-resolution simulated precipitation from Coupled Model Intercomparison Project-6 (CMIP6) experiments to examine future hydroclimate extremes over different River Basins of India. The study projected an increase in intense precipitation over the Western Ghats and Northeast river basins, and an increase in heavy rainfall intensity (14.3%) over the upper Ganga and Indus basins as well as intensification of severe droughts.

The study also highlighted an agricultural drought in the lower Ganga basin due to a decline in mean rainfall. It urged policymakers to devise strategies to cope with water surplus or scarcity.

Approximately 4% to 10% of heavy rainfall is projected to increase over the western part of Indian River basins. Under certain carbon emission scenarios, a significant increase of about 30% precipitation per day was likely over the West flowing River Kutch & Saurashtra, including Luni, Indus, and Upper Ganga River Basins.

Rainfall intensity may increase

The researchers have used the CMIP-6 climate model for analysis along with data from the Indian Meteorological Department (IMD). The results of this study indicate a possibility of an increase in the frequency of extreme rainfall in the river areas of Western Ghats and Northeast under the low emission scenario i.e., SSP1-2.6. This means that these areas may see more heavy rainfall events than ever before, which may increase the risk of floods.

The research also shows that the intensity of heavy rainfall over western India could increase by four to ten percent by 2060 under a low emissions scenario. However, if we examine the next few decades, some parts of Rajasthan and west-flowing river valleys will be the main concentration of this growth.

Under SSP2-4.5, there may be a significant increase of 14.3 per cent in the intensity of heavy rains in the upper Ganga and Indus basins. The increase in the intensity of heavy rains can have a significant impact on water management and flood preparations.

However, if we look at high-emission scenarios, the challenges in the country may become more serious. Under the high-emissions i.e., SSP-8.5 scenario, the northern, central, and western river basins of the country may face even more extreme climate events.

This also underlines the importance of curbing emissions as well as mitigation efforts to reduce its impacts. In the study, researchers have also suggested making effective strategies to deal with the worsening situation.

Global weather changes linked to climate

Recently, The University of Texas in its study had highlighted how the weather patterns are changing rapidly around the world. Areas which were once experiencing drought suddenly get flooded. Scientists have held climate change responsible for these changes, due to which such incidents are coming to the fore again and again.

Something similar has also come to light in a study published in the international journal Nature, according to which the increasing temperature at the global level is affecting not only the long term but also the daily rainfall.

According to scientists, the biggest reason for this is the change in climate, due to which the weather patterns are changing completely. The weather is becoming so irregular that it is becoming difficult to even predict it.

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