GUWAHATI, April 25 - In the North East region, climate change-induced higher agricultural vulnerability, is observed in its northern parts and the vulnerability declines towards its south, says a research paper titled ‘Climate change vulnerability profiles for North East India.’ Though it was published in about eight years back in August, 2011, the paper provides some important observations which are still relevant.
The paper says that additionally, high relative variability and inter-annual variability of rainfall have created increased occurrence of droughts and floods in the recent times, leading to uncertainty in yield and increased agricultural vulnerability.
It has projected the very high vulnerability of the districts of Tirap, West Siang, Nalbari, Changlang and Dibrugarh remain very highly vulnerable. In the future scenario, the vulnerability of West Sikkim, North Sikkim, East Sikkim and Imphal East to decrease from high to moderate levels, while the vulnerability of the districts of Bishnupur and South Tripura are projected to be decreasing from moderate to low levels. The other districts do not show much variability from the current scenario, says the paper.
It maintains that the northern part of the NE region shows a reduction in precipitation varying from 3 per cent in the northwest portion to about 12 per cent in the northeastern portion. In the remaining part of the NE region, there is an increase in precipitation varying from zero per cent to as much as 25 per cent in the central portion. Major parts of the NE region, except for some parts of Mizoram, Tripura, Manipur and Assam, show an increase in the evapotranspiration during the near-term scenario. Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.
The paper was jointly authored by 12 scholars, who included NH Ravindranath, Sandhya Rao, Nitasha Sharma, Malini Nair, Rajnith Gopalakrishnan, Ananya S Rao, Sumedha Malaviya, Rakesh Tiwari, Anitha Sagadevan, Madhushree Munsi, Niharika Krishna and Govindasamy Bala.
The scholars belonged to the Centre for Sustainable Technologies and Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, Department of Civil Engineering of the Indian Institute of Technology, Delhi. The paper was published in the Current Science, Vol 101, No. 3, August 10, 2011.
It says that even those parts of Arunachal Pradesh that showed a decrease in the precipitation exhibited an increase in evapotranspiration, all leading to increased water availability and thus lesser water vulnerability. This can only be explained by the higher temperatures that will enhance the evaporative force. However, the increase in evapotranspiration ranges from a small fraction to about 20 per cent. The reduction in evapotranspiration in the southern portion is only marginal. The trend in water yield in the North East region is similar to that in precipitation.
The reduction in water yield for Arunachal Pradesh is up to about 20 per cent and the increase in the water yield in Assam and Manipur areas is up to about 40 per cent. Both intensity of floods and drought severity are likely to increase in many parts of the NE region. There is a general increase in flood magnitude of the Barak basin, compared to the Brahmaputra basin in future, says the paper.
State-wise analysis shows that in Tripura, Mizoram, Manipur, parts of Meghalaya and Nagaland, the flood magnitude is likely to increase by about 25 per cent in the future compared to the present. Arunachal Pradesh, Assam, Sikkim and parts of Meghalaya are likely to experience floods of lower magnitude (about 5 per cent to 10 per cent less) in future, compared to the present.
The number of drought weeks during monsoon months shows an increasing trend in Arunachal Pradesh, parts of Assam, Meghalaya, Mizoram, Tripura and Manipur, to the tune of about 25 per cent increase in future. A few districts in Assam, Nagaland, Meghalaya and Mizoram show improvement in drought situation during the onset of monsoon. Many parts of the Brahmaputra basin show a tendency of extreme soil moisture stress during monsoon months, which is likely to lead to moderate to extreme drought condition, says the paper.