ment of rivers in the risk zone should be repaired to avoid breaching. Beyond this, as the storm approaches the area, nothing can be done.
6.2.6.3
Protection ofcrops against wind
Crop damage by winds can be minimised or prevented by the use of windbreaks (shelterbelts). These are natural (e.g. trees, shrubs, or hedges) or artificial (e.g.
walls, fences) barriers to wind flow to shelter animals or crops. Properly oriented
Table 6.4. Major cyclones in India and the neighbourhood
and designed shelterbelts are very effective in stabilizing agriculture in the regions where strong wind causes mechanical damage and imposes severe moisture stress on growing crops. Windbreaks prevent the loose soil being lifted by erosion and increase the supply of moisture to the soil in spring.
6.2.6.4
Tropical cyclones and storm surge
Coffee and bananas suffer the direct loss of fruits and mechanical damage due to tropical cyclones. Nonetheless, food crop losses were estimated to be higher (35%), while the livestock sector was less affected (8%, of which one fifth was poultry). The effects of strong winds in coastal areas are seen in stunted and often very sculpted trees providing the evidence of the direction of the strong winds. Fields inundated by the storm surge suffer a loss of fertility due to salt deposition, even after the sea
Chapter 6: Agrometeorological Risk and Coping Strategies 93
water has receded. The affected land takes a few years to regain its original fertil- ity.
6.2.7 Floods
Floods and droughts over India are the two aspects of weather associated with the abundance or deficit of monsoon rains. A large number of studies are available on various aspects of floods and droughts (Table 6.5).
6.2.7.1
Effects offlood on agriculture
Very intense (extreme) rainfall can result in catastrophic flood damage even though it occurs for a relatively short period of time (Table 6.6). In general, the greatest damage to agriculture results from high intensity rainstorms with sufficient dura- tion as opposed to the low intensity, long duration storms. Direct damage to grow- ing plants from floods is most often caused by depletion of oxygen available to the plant root zones. Flooding creates anaerobic soil conditions that can have signifi- cant impacts on vegetation. Root and shoot asphyxia, if prolonged, typically leads to plant death. Chemical reactions in anaerobic soils lead to a reduction in nitrate and the formation of nitrogen gas. The denitrification can be a significant cause of loss of plant vigour and growth following flooding.
6.2.7.2
Mitigation ofdamage on agricultural sector duetoflood and heavy rainfall
Soils that are saturated prior to an extreme weather event are more likely to be af- fected severely by a damaging flood than soils that are relatively dry. Fields that have recently been tilled and are devoid of vegetation are much more susceptible to water erosion. Vegetation that is able to use much of the water and that can act as a barrier to moving water (horizontally and vertically) can reduce flood sever- ity and impacts. Water storage systems (rivers, lakes, reservoirs, etc.) that are able to capture and hold most of the incoming water are usually effective in reducing flood damage.
6.2.7.3
Flooding and heavy rainfall
Soil erosion, disruption to critical agricultural activities, the logging of crops, in- creased moisture leading to increased problems with diseases and insects, soil moisture saturation and runoff, soil temperature reduction, grain and fruit spoil-
Table6.S Flood years and their category
age and transportation interruption are among the more significant agricultural impacts from heavy rainfall (Table 6.7). Direct damage to growing plants from flood is most often caused by depletion of oxygen available to the plant root zones.
Flooding creates anaerobic soil conditions that can have significant impact on veg- etation. Chemical reactions in anaerobic soils lead to a reduction in nitrate and the formation of nitrogen gas. The denitrification can be a significant cause of loss of plant vigour and growth following flooding. There is often a balance needed between retaining enough water for agricultural production and environmental health and maintaining enough available storage volume to capture incoming wa- ter and prevent floods. Crops like rice that can function effectively in saturated and even submerged conditions are appropriate for locations that flood regularly and the system becomes dependent upon regular flooding. Many other crops (e.g.
corn) would not be adaptable to such conditions and would not be appropriate al- ternatives to rice.
6.3
Crop Insurance
In India crop insurance was considered by the central government as early in 1947-48. The Indian government constituted an expert committee headed by Pro- fessor Dharam Narain, the Chairman, Agricultural Price Commission in 1970. A beginning in crop insurance was finally made in 1972 by implementing an exper- imental scheme for Hybrid-4 cotton in few districts of Gujarat State. The scheme