Water erosion accounts for more than 50 per cent of total degraded area in India
Around 91 million hectares in India is degraded land. This constitutes almost 28 per cent of the geographical area of the country, according to a new draft report on land degradation prepared by the Indian Space Research Organisation’s (ISRO) National Remote Sensing Centre (NRSC) in Hyderabad.
The report finds eight different processes by which land degradation takes place—water erosion, wind erosion, water logging, salinisation/alkalisation, acidification, glacial erosion, anthropogenic changes and others. These processes are further divided into different ways that they can happen.
Most of the degradation of land has happened because of water erosion which makes up more than half (55 per cent) of the total degraded area. This is followed by wind erosion which constitutes 15 per cent of land degradation. Among states, Rajasthan has the largest area of degraded land at 18 million hectares followed by Maharashtra. Some of the states have a high percentage of their areas covered by degraded land. For example Uttar Pradesh has more than 53 per cent of its area covered with degraded land while Rajasthan comes a close second at 52.
Surprisingly, the northeastern states also have large parts of their total land area under degradation. Most of the northeastern states suffer from acidification of their soil which reduces their productivity. Acidification takes place when the pH balance of the soil shifts towards acidic due to an excessive presence of hydrogen ions. States like Bihar and Uttar Pradesh suffer from water logging, especially during floods.
Eighteen Indian states have experienced minor to severe floods in 2018. The worst was in Kerala in August which caused a damage of anywhere between 30,000 to 40,000 crores, according to various estimates by the Kerala government, the World Bank and the KPMG. The major reason for all these flooding events was intense rainfall over a short span of time and this was highlighted by experts and the media.
In the case of Kerala, mismanagement of dams and reservoirs had also come into play. But, there was another reason for these events which has not been highlighted much by the media—degradation of land and land use change. When there is heavy downpour of water over land that is already degraded then flooding becomes more severe. It also increases the possibilities of flash floods and landslides.
The land degradation report shows that many of the flood affected states like Maharashtra and Rajasthan also have large tracts of degraded land. While Rajasthan accounts for 20 per cent of the degraded land in the country, Maharashtra has 12 per cent of degraded land. In the flood affected states of Maharashtra and Odisha the major cause for land degradation was water erosion. Floods are one of the major causes of water erosion which means that floods would further induce more floods.
At the time of floods when rains batter the earth’s surface where it has been degraded, most of the water flows into the water bodies and becomes surface run-off. This in turn leads to low retention of moisture in the soil which leads to droughts. Ten Indian states have either declared a drought or are in the process of doing so.
Eight of these drought affected states like Maharashtra, Karnataka and Assam had earlier suffered from floods. In some instances the same districts that were flooded before will now be suffering a dry season. In the context of risk management in the case of floods and droughts these factors also need to be accounted for. In fact “soil moisture retention and surface run off along with precipitation and evapotranspiration are the major factors that will help us understand the impacts of climate change at the local level”, K J Ramesh, director general of the India Meteorological Department said.
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