Desertification: meaning, primary causes and impacts

Introduction

Deserts are natural ecosystems, but desertification is not natural growth of the desert. It is the loss of the productive capacity of land, mostly in dry regions, caused by the way people use the land and made worse by drought.

Meaning of desertification

Desertification is the process by which productive land in arid and semi-arid areas degrades until it behaves like a desert: plant cover thins out, the soil loses its fertility and moisture, and the land can no longer support crops, pasture or forest. It spreads together with deforestation and large-scale changes in land use, as forest and grass cover are lost and the water table falls. It is therefore a form of land degradation, seen most sharply where rainfall is low and uncertain.

Primary causes of desertification

1. Overgrazing. When too many cattle, sheep and goats graze a grassland too often, it becomes bare, the soil is compacted by trampling, washed away in the monsoon and whipped into dust storms in summer; with no grass left to hold it, the land becomes wasteland.
2. Deforestation and changes in land use. Clearing vegetation exposes the soil and lets rainwater run off instead of soaking in; with deforestation and wider land-use change, desertification spreads.
3. Faulty irrigation in dry lands. Canal water spread over desert soils evaporates fast and brings salts to the surface, so the land turns saline and unproductive; pulling too much groundwater through tube wells adds to the drying. In the Deccan, grasslands converted to irrigated sugarcane became saline and useless within a few years.
4. Drought. In arid regions rains are unpredictable and droughts follow the failure of one or more monsoons; repeated drought on land already stripped of cover speeds its decline.
5. Population pressure and development projects. Growing human numbers and development strategies have begun to change the natural desert and semi-arid ecosystem.

Impacts of desertification

• Loss of productive land and food. Saline and eroded land becomes highly unproductive, cutting crop and fodder output.
• Water problems. As vegetation and soil cover are lost, sub-soil water tables drop, once-perennial rivers become seasonal, small streams dry up soon after the monsoon, and rapid surface run-off in the rains causes floods with loss of life and property.
• Dust storms and air quality. Bare soil is blown into dust storms in the hot, dry season.
• Loss of biodiversity. The habitat left for specialised desert and grassland species shrinks sharply, pushing them towards extinction.
• Hardship and poverty. Drought years bring food shortages and malnutrition, especially among children, and leave farmers without income.

An example of our own: a village in western Rajasthan that ploughs up its common grazing land and over-pumps its tube wells may first see its wells go deeper, then saline patches in its fields, and finally sand drifting over abandoned plots.

Conclusion

Desertification is largely human-made and therefore preventable. Controlled grazing, protection of tree and grass cover, careful irrigation and water conservation can halt it, and restoring the land is far cheaper than living with its loss.