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Synopsis: Changing rainfall pattern including incidents of high and variable rainfall in NE states is causing problems like floods, land degradation and acidification.
The climate of North East India is changing, which includes changing rainfall patterns over the region, resulting in overall drying up of the region. A major reason behind it is the drying up of around 200 mountain springs which are direct primary sources of water for mountainous villages in the region.
The region is ultimately facing climate induced water crisis. Action plans on climate change by the northeastern states have identified the change in rainfall patterns as one of the major causes of vulnerability to climate change.
Why are springs important to NE states?
Contribution to rivers: The springs contribute a large share to the base flow of the large Himalayan rivers such as the Brahmaputra — more than glaciers, ice and snow.
Meeting water needs: Moreover, the mountainous regions of the northeastern states are mostly dependent on these springs to meet their water needs.
Why Assam is more vulnerable to climate change as compared to other NE states?
Groundwater levels: In Assam, the groundwater levels are closely related to the flow of water in the Brahmaputra, which means that the difference between the river flow levels and the ground water levels is less. Hence, a little rainfall in the catchments will affect the flow of the rivers and along with that the ground water levels will also be impacted.
Soils: Brahmaputra has mostly sandy soil and their water retention capacity is low, which creates a scare of water scarcity.
Irrigation: As per a study, Assam has the least area under irrigation, least forest area available per 1,000 rural households and the second lowest per capita income among the Indian Himalayan states. It is the most vulnerable to climate change. Mizoram is the next one.
Why have springs dried up?
The drying of springs in North East India may be because of human-induced geological and land use changes, along with the impact of climate change, especially rainfall.
The exact cause needs to be ascertained.
What are some negative consequences of changing rainfall pattern in NE states?
Land degradation: Another consequence of the untimely and excessive rains is that large parts of northeastern states have become degraded, which has a direct consequence for the region’s main occupation — agriculture.
Causes behind land degradation:
i) One of the major causes of this degradation could be increased frequency of high rainfall events in the region.
ii) Another common cause of land degradation in these states is acidification. In the top eight states in the country where acidification is the most rampant, seven are in the northeast.
Land in the North East is naturally acidic because it receives heavy rainfall every year. Climate change-induced high frequency of heavy rainfall events will further exacerbate the acidification, which will decrease the quality of soil.
|Acidity is measured in terms of the concentration of hydrogen ions (pH) in the soil, as they are essential for the formation of all acids. Acidification of soil or land takes place when the pH balance of the soil shifts towards acidic nature due to an excessive presence of hydrogen ions.|
Soil acidity increases when metallic minerals such as calcium, magnesium, potassium and sodium are lost from the soil and only hydrogen ions remain. These minerals get removed from soils due to heavy rainfall and flooding. They also get removed with crop residue or harvest hay.
Reducing acidification of the soil
We can use lime and organic manure in the soil and can adopt nutrient management practices and smart crop selection.
Source: This post is based on the article “Climate crisis in North East India: What is behind water scarcity in the region” published in Down to Earth on 10th September 2021.