Drying up of water springs, land degradation, sandy soils of the Brahamputra point to a grim situation in the region
In the third part of the series tracking climate change in North East India, Down to Earth reported on the many factors causing changes in rainfall patterns in the region. These included drying of the land and increased snowfall in the Eurasian region — which point to increasing concern of the impact of climate change on the region.
The climate of North East India is changing: Rainfall patterns over the region in the last century have considerably changed, resulting in its overall drying up.
The crux behind climate change-induced water problem in the North East is the drying up of the mountain springs, which feed every other water source in the region.
As many as 200 mountain springs, direct primary sources of water for mountainous villages in the state, have dried up due to a decrease in rainfall, Arunachal Pradesh’s environment minister had said in 2018.
“With climate change and rising temperatures, rise in rainfall intensity and reduction in its temporal spread as well as a marked decline in winter rain, the problem of dying springs is being increasingly felt across the Indian Himalayan Region,” a NITI Aayog report said.
This points to a grim situation for all mountainous regions of the northeastern states as they are mostly dependent on these springs to meet their water needs. In Sikkim, over 94 per cent villages have mountain springs. In Meghalaya, Mizoram and Manipur, 55.7, 54.6 and 54.4 per cent villages have them.
Nagaland and Arunachal Pradesh have 44.7 and 37.3 per cent villages with springs. 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 — according to the report.
This means that those living in the plains, especially in Assam, will also be affected by the drying up of these springs. “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,” said Mahanta.
The springs have to be studied in great detail to ascertain the exact causes of the decrease in water flow. But Assam has another worry: The groundwater levels are closely related to the flow of water in the Brahmaputra.
“This is because the change in Brahmaputra’s altitude is only 90 metres between its entry into the plains in Pasighat (Arunachal) and its forming of a delta (in Bangladesh). This means that the difference between the river flow levels and the ground water levels is less. So if there is little rainfall in the catchments it will affect the flow of the rivers and along with that the ground water levels will also be impacted,” said Patnaik.
Another aspect is that the soils of the Brahmaputra are mostly sandy and their water retention capacity is low, which creates a scare of water scarcity.
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,” found a climate vulnerability assessment by Indian Institute of Technology Mandi, Indian Institute of Technology Gandhinagar and Indian Institute of Science, Bangalore.
These factors make the state, among other Himalayan states, the most vulnerable to climate change. Mizoram comes second close based on similar reasons.
The assessment was carried out using four broad indicators: Socioeconomic, demographic status and health, sensitivity of agricultural production, forest dependent livelihoods and access to information services and infrastructure. These were then divided into more sub-indicators. Among the top five states most vulnerable to climate change in the Himalayan region, four are from North East India.
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. The riverine islands of the Brahmaputra, for example, have been identified as the most vulnerable to health impacts of climate change owing to frequent floods caused by heavy rainfall in the region and in upstream areas.
Assam’s state action plan on climate change said:
“According to the Union Ministry of Development of North Eastern Region and the North Eastern Council, those living on the small islands in the Brahmaputra are the most vulnerable to disease outbreaks. They are isolated from the rest of Assam, have no permanent healthcare facilities and are prone to frequent flooding. As climate change continues, these islands will become increasingly vulnerable and hence public health facilities need to be extended to such areas effectively”.
Assam experienced major floods in 1954, 1962, 1972, 1977, 1984, 1988, 1998, 2002, 2004 and 2012.
The state suffers losses of Rs 200 crore or more every year due to foods, according to the state’s government.
“Crop failure due to high rainfall variability and increased crop water needs” is identified by Manipur’s state action plan on climate change as one of the major impacts of climate change on agriculture and its allied sectors in the state. The state does not suffer from floods usually, but has witnessed some in recent years.
For instance, in June 2018, the most flood-affected districts — Imphal, Ukhrul and Thoubal — covered 25 per cent of the total area of the state.
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.
Land in the northeastern states has become degraded to a great extent, according to a draft report on land degradation prepared by the Indian Space Research Organisation’s (ISRO) National Remote Sensing Centre (NRSC) that came out in November 2018.
Among the top seven states with the highest increase in land degradation in the last 10 years, six are in the North East. Nagaland has 47 per cent of its land area under degradation, after Uttar Pradesh and Rajasthan, which have 53 and 52 per cent degraded land area.
In Manipur, Mizoram and Meghalaya, 38, 35 and 28 per cent of land is degraded. One of the major causes of this degradation could be increased frequency of high rainfall events in the region. The degradation could, in fact, be one of the reasons for the devastating surface floods, flash floods and landslides throughout the region of the country in 2018.
Five states — Assam, Manipur, Tripura, Mizoram and Nagaland — suffered from minor to major floods in 2018. More than water erosion, which worsens floods, the report found that the most 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. The highest among these is Nagaland where almost 7.5 lakh hectares of land area is acidic which constitutes around 45 per cent of the total area of the state. Manipur comes second with 6.3 lakh hectare acidified land, which is more than 28 per cent of its total geographical area.
Only in Arunachal Pradesh and Assam the degradation caused by water erosion is greater than that caused by acidification.
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.
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.
In a region that is predominantly dependant on agriculture, with 70 per cent of the population engaged in farming, such loss of arable land could spell doom for livelihood. Using lime and organic manure in the soil can help the situation. Acidification can also be remedied by adopting nutrient management practices and smart crop selection.
Land degradation exacerbates other impacts of climate change too. The region is rich in biodiversity. As many as 5,000 of the 17,000 flowering plants in the country are found in the region.
Dams and other constructions as well as deforestation have compounded the challenges posed by the crisis. “The most dramatic changes in the land use in the North East, especially Assam, has come from the arrival of sand that is much coarser than before,” said Arupjyoti Saikia, professor of economics, IIT Guwahati.
The volume of sediments carried by the Ganga and Brahmaputra every year can be loaded into 20,000 million trucks, Saikia added. The sand in Brahmaputra has now become coarser, replacing the earlier softer sand and more fertile alluvial soils that is bad for agriculture.
This sand has had a visible impact on the rice fields of Assam, whose productivity has diminished.
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