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1.6 drought
 

1.6 drought

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  • Press play – the water cycle will play out on the screed.

1.6 drought 1.6 drought Presentation Transcript

  • Drought Presented byCT.Lakshmanan B.Arch., M.C.P. SRM School of Architecture SRM University
  • What is Drought?Drought occurs when more water is taken out of thesoil than is added to it. This is often the result of acombination of many days without rain andexcessive use of water for human activities.According to the UN, an area of fertile soil the size ofUkraine is lost every year because of drought,deforestation and climate instability. Prepared by CT.Lakshmanan 2
  •  One of the greatest threats to people from a drought occurs when agricultural regions receive unusually low amounts of rain, causing vegetation to become dry. When this happens, crop yields can decrease dramatically, often resulting in increased food prices, food shortages, and even famine. At the same time, decreased drinking water quality and availability puts additional strains on our health. Prepared by CT.Lakshmanan 3
  • Causes Rainfall is related to the amount of water vapour in the atmosphere, combined with the upward forcing of the air mass containing that water vapour. If either of these are reduced,the result is a drought.Factors include: Above average prevalence of high pressure systems; Winds carrying continental, rather than oceanic air masses (ie. reduced water content); Ridges of high pressure areas form with behaviors which prevent or restrict the developing of thunderstorm activity or rainfall over one certain region; Deforestation and erosion adversly impacting the ability of the land to capture water; Climate change has a substantial impact on agriculture Prepared by CT.Lakshmanan 4
  • Droughts can be of three kinds (i) Meteorological drought: This happens when the actual rainfall in an area is significantly less than the climatological mean of that area. The country as a whole may have a normal monsoon, but different meteorological districts and sub-divisions can have below normal rainfall. The rainfall categories for smaller areas are defined by their deviation from a meteorological areas normal rainfall - Excess: 20 per cent or more above normal Normal: 19 per cent above normal - 19 per cent below normal Deficient: 20 per cent below normal - 59 per cent below normal Scanty: 60 per cent or more below normal (ii) Hydrological drought: A marked depletion of surface water causing very low stream flow and drying of lakes, rivers and reservoirs (iii) Agricultural drought: Inadequate soil moisture resulting in acute crop stress and fall in agricultural productivityEarlier years of all-India drought 1987, 1979 Prepared by CT.Lakshmanan 5
  • Damages due to extreme events between the period 1900 to 2004 180 1600 156 no. of events Total no. of people affected 150 133 total affected 1200 120 No. of events 90 800 60 37 37 400 30 21 0 0 Extreme Land slides Wind Storm Flood Drought Temperature Number of people affected due to various extreme events in India. Prepared by CT.Lakshmanan 6
  • Probability of Occurrence of Droughts A perennial feature 19% of area affecting 12% of population annually Frequency of droughts: Tamilnadu, J&K, Telangana, West Rajasthan - every 2.5 years Gujarat, E. Rajasthan & Western Uttarpradesh – every 3 years Other states have droughts every 4-5 years Based on the rainfall deficiency for the last 100 years Prepared by CT.Lakshmanan 7
  • Prepared by CT.Lakshmanan 8
  • Severe droughts in India in last 100 years Year % of country % of less % of less area affected rainfall over rainfall over entire India drought reg. 1918 71 -26 -49 1965 41 -17 -36 1972 47 -25 -35 1979 45 -21 -38 1987 50 -18 -45After 1987, India experienced severe drought in 2002, where 29% ofthe area was affected Prepared by CT.Lakshmanan 9
  • Temporal-spatial spread of drought & impacts Drought is occurring in some or the other part of the country1984 2000 Primary impacts: water availability, agriculture production, hydropower generation Secondary Impact: Agricultural GDP dips,1986 2001 increase in commodity prices, livelihood of people dependent on rainfed farming (marginal farmers & farm laborers surviving) affected1997 2002 Rainfed areas (61%) – most affected Prepared by CT.Lakshmanan 10
  • Damages due to droughts 3000 1800 cropped area affected/ cattle 1600 2500 Number of Districts 1400districts /population affected 2000 1200 Population affected 1000 (lakh) pop. 1500 800 Cropped Area affected (lakh ha) 1000 600 Cattle population 400 500 affected (lakh) 200 0 0 1984 1985 1986 1987 Prepared by CT.Lakshmanan 11
  • Risks associated with droughts Depletion in water resources for agriculture and drinking : women walk 1-2 kms to fetch water Reduction in crop yields and change in cropping pattern Dwindling fodder stock and declining income of farmers lead cattle selling; esp. marginal and small farmers who sell at depressed prices Increased incidences of debt: Decline in nutrition and health status: malnutrition strikes (esp. among children and women) whenever drought occurs Prepared by CT.Lakshmanan 12
  • Traditional coping strategies in response to drought Physical Household/Community  Migration (15-30%)  Sale of assets (land, livestock, durable assets)  Reduce intake of food and decline in other expenditure  Shift from superior to inferior food grain  Mixed cropping State/Government  Food distribution system  Water supply (tanker, new wells etc)  Employment programs Prepared by CT.Lakshmanan 13
  • Traditional coping strategies in response to drought (contd.) Social Economic Sharing and cooperation Borrowing Sacrifice by senior members Imports/assistance New Community Diversification in source of relationships income Inter and intra community Subsidy/grants exchange programs - Relief works Prepared by CT.Lakshmanan 14
  • The water cycle
  • Modern coping strategies Coping with water shortages requires a basic understanding of how the Earths water cycle operates. There are usually many inputs and outputs for any reservoir. When too much water is removed from a reservoir relative to how much is added, a drought may soon follow. Water conservation is the most effective method for mitigating droughts. Farming techniques to retain productivity during droughts Soil & water conservation practices Farm Pond : enables storing runoff water Xeriscaping, which involves planting drought-tolerant species Prepared by CT.Lakshmanan 16
  • Consequences Periods of drought can have significant environmental, agricultural, health, economic and social consequences. Examples include: Death of livestock. Reduced crop yields. Wildfires, such as Australian bushfires, are more common during times of drought.[28] Shortages of water for industrial users.[29][30] Dust storms, when drought hits an area suffering from desertification and erosion Malnutrition, dehydration and related diseases. Famine due to lack of water for irrigation. Social unrest. Substandard or highly limited crop growth or yield productions. Mass migration, resulting in internal displacement and international refugees. War over natural resources, including water and food. Reduced electricity production due to insufficient available coolant for power stations[31] and reduced water flow through hydroelectric dams.[32] Snakes have been known to emerge and snakebites become more common.[33][34] Creates windblown dust bowls which erodes the landscape, damages terrestrial and aquatic wildlife habitat Prepared by CT.Lakshmanan 17
  • Conclusion - drought Marginal & small farmers and landless are most vulnerable to drought Middle level farmers have also fallen prey to recurrent droughts due to:  Decline of crop acreage  Fall in water table & water harvesting structures  Fall in employment & purchasing power  Scarcity of food and fodder  Lack of change in cropping pattern & lack of drought resistant seeds  Inability of farmers to repay loans with continuous droughts Dominant strategies in drought prone areas:  Adopting mixed farming system (crop, livestock & agro- forestry)  Resources conservation approach  Collective sustenance Prepared by CT.Lakshmanan 18
  • Thank You Prepared by CT.Lakshmanan