High human and livestock pressure on the sandy lands bereft of natural vegetation cover, are resulting in serious soil erosion and dust emissions. Unless we gear up our efforts to increase the perennial vegetation cover several fold, link it with alternative livelihood development for economic well-being, start conserving water and make sincere efforts to recharge our depleted groundwater aquifers, there is every chance that high incidence of sand/ dust storms would start engulfing our prime cultivated lands.
The dried up aquifers forced many farmers to shift back from the irrigated winter cropping to the rainfed subsistence farming in monsoon, which led to new socio-cultural problems
‘Desertification’ is a slow and less perceptible process that gradually leads to the decline of production potential of the land, thus affecting the socio-economic conditions of people whose livelihoods depend on that land.
The arid western part of Rajasthan and Gujarat states are the most vulnerable to desertification in India. While periodic droughts and floods are the natural triggers for accelerated land degradation, these are essentially integral to a dryland climate, thus are generally cyclical.
In contrast, the human pressures on the land are progressive in nature and non-cyclic, which make the land increasingly more prone to degradation if adequate measures are not taken to arrest the degradation.
A recent assessment by Central Arid Zone Research Institute (CAZRI) shows that about 18% area of western Rajasthan is now severely affected by desertification and 66% slight to moderately, while the rest 16% is largely unaffected. In arid western Gujarat, about 44% area is severely affected, 53% slight to moderately, and the rest 3% is almost unaffected.
Mounting pressure on desert lands
One of the major reasons for very high wind erosion in western Rajasthan is the high human and livestock pressure on the sandy landforms. As population growth and modernization of agriculture progressed in the post-independence era, the traditional system of land fallowing became the first major casualty. Permanent pastures became almost bereft of ground flora, and brows-worthy shrubs became fewer. At the same time, the sparse natural woody vegetation on the sand dunes and low sandy hummocks gradually became the targets of fuel wood collectors, making the sand dunes more vulnerable to wind.
Over the decades, tractor ploughing has become the single major factor of potential sand and dust blowing activities. More land is being opened for cropping (mainly irrigated cropping) in the sandy terrain. Deep tillage with tractors has replaced the traditional plough. The natural vegetation cover along with its intricate root structure gets destroyed over much wider areas, thus causing more of soil erosion in the pre-kharif months of May and June.
Tractor operation becomes difficult in a shrub/tree dominated area. Thus, the easiest way is to clear the natural vegetation cover. This has severely affected the traditional agroforestry system of the region, a highly sustainable practice for centuries under rainfed cropping system. As tractor-ploughing became omni-present even on the higher slopes of the sand dunes, and natural vegetation cover diminished. A huge loose sandy area became available to the strong pre-kharif summer wind for mobilization. Consequently, with each episode of dust/sand storm, the soils are rapidly becoming poorer with loss of silt, clay as well as the precious plant nutrients.
Apart from erosion of the topsoil, containing the little organic matter, the other major impact of wind erosion is the damage to crop plants, burial of good agricultural land and infrastructure, and disruption of transportation network. Broadly, the western-most part with finer soils, higher wind strength, more dryness and poorer plant cover is a major source of atmospheric dust, which gets carried eastwards during the dust storms and gradually settles in the eastern part of Rajasthan and adjoining parts of Uttar Pradesh and Madhya Pradesh.
Irrigation, a trigger to land degradation
Salinization is dominant in the groundwater-irrigated south-central part and canal-irrigated northwestern part of western Rajasthan. Over-irrigation, lack of proper drainage in an alluvial plain dominated by buried stream courses, and seepage from the canals are the root causes for the rise in water table and build-up of salinity in the canal command areas. Also, irrigation with groundwater having salinity/high residual sodium carbonate is a spoiler elsewhere. Till now, irrigation in the desert has led to huge increase in crop production, especially in winter crops, fetching large income for the farmers.
Water management in irrigated areas has, however, remained a neglected field. Farmers of the Indira Gandhi Canal command area have learnt their lessons after their prime lands had to be abandoned due to water logging and salinization. The recently commissioned Narmada Canal project in the southwestern part of western Rajasthan needs to learn lessons from some of the environmental issues raised by the faulty water management in the Indira Gandhi Canal command area. This will enable in taking corrective measures in time, especially because, part of the canal network runs through areas having highly saline soils as well as saline groundwater at shallow depth.
Elsewhere in the desert, groundwater being a free commodity and farmers being enthused by the success of irrigation, over-irrigation of fields has gradually become a rule. Presently, the well-irrigated area is about 60% of the total irrigated lands, the rest being under canal irrigation. Over the decades, as pumping of groundwater increased, the discharge from many wells began to dwindle, and the aquifers began to dry up. The affected farmers started going deeper for water, which not only escalated the cost of lifting water, but in many cases, the lifted water was also found to be of poor quality.
The soils got affected and the yield was reduced. Irrigated farming then became either un-remunerative or difficult to pursue due to dried up aquifers. This forced many farmers to shift back from the irrigated winter cropping to the rainfed subsistence farming in monsoon, which led to new socio-cultural problems for the affected families. Many farmers have now resorted to sprinkler and drip irrigation.
The erstwhile fields, now bereft of natural vegetation cover, are becoming the new foci of wind erosion and dust emission. In other words, irrigated cropping is becoming a trigger for wind erosion in longer term! Sadly enough, groundwater use for drinking purpose constitutes currently about 15% of the total extracted, while that for irrigation is about 80%!
It’s time for action
Presently, the three major environmental issues in our desert are water management, land quality and dust emission, all being interrelated. The dwindling groundwater reserve has forced the state to stop digging for irrigation in many affected areas. But, more efforts are needed to enforce water management and promoting crops / varieties that demand less water, which are heat and drought tolerant. This is needed owing to higher warming trend linked to climate change, as well as shifts in rainy days and rainfall intensity during the monsoon months.
Water storage and conservation need to be given a strong boost, with emphasis on groundwater recharge. At the same time, wind strength is expected to increase severalfold in the coming decades. This will lead to more blown-sand activity, higher loss of precious soil nutrients and higher atmospheric dust load, assisted by the churning up of a large sandy tract through tractors and the depleted soil moisture in a warmer climate. The eastern fringe of the Thar faces a higher threat of sand mobilization and spread.
Recent studies show that the increased atmospheric dust load from the Thar has already started affecting the monsoon rains in the east-central India. This, therefore, calls for a policy shift to keeping more sandy lands under permanent vegetation cover, especially through agroforestry and management of pastures, rangelands and sand dunes. People’s participation in the activities can be expected only when there are assured returns to the stakeholders. Hence, the management strategies should be based on well-researched alternatives that are acceptable to the stakeholders.
For example, people may be encouraged to manage pastures and rangelands if the state can build adequate infrastructure and market facilities crucial for dairying and other animal-based economies, which could be lucrative enough for villagers in managing their livestock better.
The arid parts of Gujarat might face a greater problem of water erosion, as rainfall and its intensity is gradually increasing. Since the soil depth is low and slope is high, higher rainfall intensity leads to faster depletion of topsoil, unless adequate conservation measures are in place. These areas need better soil conservation measures.
Salt water ingress in the aquifers of the coastal belt poses another threat due to higher withdrawal of groundwater. Unless we gear up our efforts to increase the perennial vegetation cover several fold, link it with alternative livelihood development for economic well-being, start conserving water and make sincere efforts to recharge our depleted groundwater aquifers, there is every chance that high incidence of sand/dust storms would start engulfing our prime cultivated lands.
Dr. Amal Kar
Former Principal Scientist and Head,
Division of Natural Resources & Environment,
Central Arid Zone Research Institute,
Jodhpur, A 1/6, Baitalik Housing Society, KMDA Housing Complex,
Baghajatin (near Hiland Park),
Kolkata 700 094.