Soil erosion in India by Chris Dunstan Cynffig

Soil erosion in India by Chris Dunstan Cynffig Comprehensive School

Key idea on WJEC specification § 1. 6 Key question : What are the environmental challenges and solutions facing India? § The causes and consequences of soil erosion

What are we learning? § What are the causes of soil erosion? § Himalaya case study, Terai Nepal § What are the effects of soil erosion? § What ways can you manage soil erosion? § Case study : Management of soil erosion in the Rajasthan Desert § Soil not oil

What are the Causes of soil erosion ? In the forests of Assam and Madhya Pradesh, shifting cultivation, is practised by the tribal people in these areas, is a major cause of destruction of forests. Unregulated grazing In the north-western Himalayas, grazing by cattle, sheep and goats is the most important cause of depletion of the vegetation cover and soil erosion. §Intensive felling to obtain supplies of fuel or timber, and clearance of forests for extension of cultivation under the pressure of demand for agricultural land from the increasing population.

4. Considerable erosion results from faulty land use practices on farmlands themselves. Failure to practise such measures as ploughing along the contours on sloping lands, proper crop rotations and in particular growing of cover crops are causes of erosion. 5. Deforestation Vegetation acts as a protective cover against the forces of wind and water and protecting the soil from being washed or blown away. Forests, provide the most effective protection against erosion on hill slopes. They break the force of run-off by impeding the flow of rainwater down the slopes and by absorbing large quantities of it in their dense mat of undergrowth.

§This absorbed water flows away slowly over a period of time In this way, the hill slopes are protected from erosion, the flow of streams is regulated, the danger of floods is reduced and sufficient quantities of water are available in dry periods. When the protective cover of forests is destroyed rainwater flows down the slopes unimpeded at great speed and carries with it large quantities of soil and other loose material. The hill-slopes are denuded of valuable soil and in the foot-hill zone where this mass of sands and gravels is deposited are rendered unproductive. §Most of the water flows away during the rainy periods with the result that on the one hand floods are more frequent and more severe and, on the other, little water is available during the dry periods. Ground-water, supplies are also reduced as much less water is absorbed in the soil than before.

Deforested & eroded Hillslopes

Pupil task: flowchart design § Produce a flowchart to show the causes of soil erosion that are associated with DEFORESTATION. You could use some of these key words: § Floods § Runoff § Underground vegetation mat § Protective cover § Foot hill § Ground Water supplies

HIMALAYAN Terai, Nepal Soil erosion case study § 90% of the population are rural subsistence farmers. § Increases in fuel wood demand, fodder tree cutting and construction means that Deforestation rates have increased § Terrace construction for agriculture on steep marginal land has led to increases in soil erosion.

§ Reductions of fuel wood supply lead to increased use of dung for fuel reducing nutrient status of hill slope soils. § Terrace soils degrade - giving higher erosion rates § Changes in river flow regime and high sediment yields lead to river bed deposition and increased siltation of reservoirs and increased flood stages on the Gangetic plain.

What are the Effects of soil erosion ? § Physical damage is the most visible form of soil loss. Gravity pulls constantly at soil, moving it down hill, causing soil slips, earth clips, cracks, creep and slumps. § Monsoon rainfall is a major source of soil erosion. The results from this study estimate current soil erosion rates for Kerala to be in the order of 19 -150 tonne/ha/yr which are higher as compared to non-monsoon rainfall erosion of the UK of 0. 23 -1. 5 tonne/ha from a typical site.

What ways can you manage soil erosion ? 1. Regulation of land use. —Retiring cultivated lands in highly erodable areas from cultivation and bringing them under forests or grazing ; restrictions on or closure of grazing in badly eroded areas, and settlement of shifting cultivators to permanent cultivation. 2. Afforestation and preservation of forests by scientific forest management. § 3. Improvement of land use practices on farm lands. This includes such measures as ploughing along the contours and strip-cropping on sloping lands; proper crop rotations ; application of adequate manures and fertilizers 4. Engineering measures. —Under this are included construction of bunds and terraces, check dams and channels for drainage of surplus water.

Why is it soil conservation important for India ? § Soil conservation if of utmost importance for a country like India which is mainly has an agricultural economy. § A large part of India’s population depends on the soil for their livelihood and hence soil erosion and the measures of soil conservation taken up to prevent soil erosion are of key concern for the Indian government.

Case study : Management of soil erosion in the Rajasthan Desert § What is the Issue? = Desert and semi-desert conditions occur in Rajasthan and there has been advance of the desert and encroachment of sand on fertile lands due to desertification and soil erosion. § There has been a programme of action which includes: 1. Creation of a vegetation belt—five miles wide—along the western border of Rajasthan. 2. Improvement of land-use practices, especially the creation of shelter belts of trees by cultivators 3. A Desert Research Station is being set up at Jodhpur to investigate the problems of desertification. Research on soils, land-use and afforestation practices would be undertaken at this station.

Soil not oil § Condemning industrial agriculture and industrial bio fuels as recipes for ecological and economic disaster, Shiva’s champion is the small, independent farm. § What we need most in a time of changing climates and millions hungry, she argues, are sustainable, biologically diverse farms that are more resistant to disease, drought, and flood. Calling for a return to local economies and small -scale food production. § In Soil Not Oil, Indian scientist and agricultural activist , Dr Vandana Shiva, connects the food crisis, peak oil prices and climate change to show that a world beyond a dependence on fossil fuel and globalization is both possible and necessary.

Terai, Nepal: Khet Terraces

Thank you to the following for allowing use of the images: § § § www. grida. no/general/2832. aspx www. theglaciertrust. typepad. com www. unu. edu/mountains 2002/photoexhib it/descriptions. htm