‘Global-Warming Will Increase Water Flow In South Asian Countries’

Mismanagement of the water flow will exacerbate floods, water logging and land erosion, experts say.

A wetter future awaits South Asia, says a new study based on global cli­mate change models that informed the fifth assessment re­port of the UN’s Intergovernmental Panel on Climate Change.

The South Asia region will see a 20%-30% increase in mean annual run­off for the period 2046-2075 relative to the study baseline period of 1976-2005, says Hongxing Zheng, corresponding author of the study published in August in the Journal of Hydrology: Regional Studies. The study was carried out by the Com­monwealth Scientific and Industrial Re­search Organisation, Australia.

“We also discovered that the per­centage change in precipitation may amplify by 1.5%-2% in wet areas and by more than two per cent in dry areas,” Hongxing told SciDev.Net.

South Asia is home to 54 rivers of varying sizes linked to the Indus, Gan­ges and Brahmaputra river basins, all originating in China’s Tibet Autono­mous Region. While the Indus basin connects China with Afghanistan, India and Pakistan, the Brahmaputra and Ganges basins connect Bangla­desh, Bhutan, China, India and Nepal.

“A spike in mean annual runoff of about 10% is projected for the Indus, Ti­betan Plateau and Arakan Coast regions, and about 15% in the Ganges-Brahma­putra, Deccan Plateau and Ghats Coast regions,” Hongxing said, adding that the spike will be over 20% in the Narmada- Tapti region and Sri Lanka.

Hotter days

The change will be driven by high­er temperatures from global warming, leading to more rain, according to the study. Average daily temperatures would rise by 2.9-4 degrees Celsius in 2046-2075, relative to the baseline. It also says the winter season will be slightly warmer and the summer sea­sons may see noticeably higher tem­peratures, especially in the northern (high altitude) regions.

Arun Shrestha, manager of the river basins programme of the Inter­national Centre for Integrated Moun­tain Development Centre, Kathmandu, said that until recently hydrologists and climatologists perceived runoffs across South Asia as reducing due to climate change. “But field and satellite imagery show that water availability is likely to increase – this is consonant with the new study on runoff scenarios for all the rivers.”

Managed properly, Shrestha said, increased runoffs could help socio-eco­nomic growth and poverty reduction in countries of South Asia which largely rely on farming. However, failing to do so will exacerbate floods, land erosion, water logging, droughts and related im­pacts, he warns.

Food security and farm-based live­lihoods expert at Mountain Develop­ment Centre, Golam Rasul, suggests “investing in flood-resilient farming systems, flood-tolerant crop varieties and infrastructure as well as collabora­tion among South Asian countries for joint river basin management and ear­ly flood-warning systems to mitigate projected impacts.”

This Article First Appeared On SciDev Net.


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