Draught natural disaster

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DROUGHT 1 Drought

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  • 1. DROUGHT1Drought

2. IntroductionDefinitionCausesSummary of common causes of draught inIndiaDrought classificationEffects of draughtCase StudyGovernment policies to combat droughtsDrought2 3. I n t r o d u c t i o nWe can feel the dryness in your throat. The land is barren and covered in thin dust.cracks appear in the earth. This is drought, when water is so scarce that theexistence of life becomes threatened. How do humans effects from drought?Drought3W h a t s a d r o u g h t ?A drought occurs when there is not enough rain to support people or crops. Intemperate regions, a drought is classified as 15 consecutive days with less than 0.01inches (0.25 millimeters) of rain.A drought (or drouth [archaic]) is an extended period of months or years when aregion notes a deficiency in its water supply. Generally, this occurs when a regionreceives consistently below average precipitation. It can have a substantial impacton the ecosystem and agriculture of the affected region. Although droughts canpersist for several years, even a short, intense drought can cause significantdamage and harm the local economy. 4. Drought4C a u s e s o f d r o u g h t s1. Less rainfall: We already know that a drought occurs when not enough rainfalls to the ground. However, water vapor condenses only if air rises into thecolder regions of the atmosphere. If the air doesnt rise, then no rain will form.2. High Air pressure: When there is high air pressure, air falls instead of rising.With the air pressing down in a high pressure zone, no currents of water vaporare carried upward. As a result, no condensation occurs, and little rain falls toearth. In addition, high-pressure areas push clouds and air currents downwardand away, resulting in sunny, cloudless weather.3. Low air pressure: Low-pressure systems see more cloudy, stormy weather.Usually, however, we experience both high- and low-pressure systems.4. It is normal for a high-pressure system to pass over an area and move on,being replaced by a low-pressure system. However, when a high-pressuresystem is stalled, the sunny weather can drag on for days. If it keeps on going,the result is a drought. 5. Drought5move from place to place can be locked in one area by jet streams.6. Monsoon role: Usually, summer winds known as monsoons carry water vapornorth from the Indian Ocean inland, providing desperately needed rain.Sometimes, however, instead of blowing from north to south, they blow east towest. When that happens, the vapor doesnt leave the Indian Ocean and manypeople suffer from the resulting droughts.7. Water Vapor role: Droughts occur because water vapor is not brought by aircurrents to the right areas at the right times. Water that evaporates from theoceans is brought inland by wind to regions where it is needed. However,sometimes those winds are not strong enough.8. Moisture: In some states, moisture is carried up from the ocean by blowingwinds. This moisture is then pushed by other winds until it reaches the location.However, if the winds dont blow at the right time, in the right direction, or withenough force, the moisture falls in other areas and suffers from drought.9. Mountains region wind: Mountains can prevent wind from blowing moisture toneeded regions. As air is moving past a mountain range, it is forced to rise in orderto pass over the peaks. However, as the air rises, it becomes colder and the vaporcondenses into rain or snow.The rain then falls on that side of the mountain, known as the windward side (theside that is 6. Drought6turned toward the wind).When the air mass finally makes it over the mountain, it has lost much of its vapor.This is another reason why many deserts are found on the side of a mountain facingaway from the ocean. This phenomenon is known as the rain shadow effect.10. Rainfall pressure: Generally, rainfall is related to the amount of water vapor inthe atmosphere, combined with the upward forcing of the air mass containing thatwater vapor. If either of these are reduced, the result is a drought. This can betriggered by an above average prevalence of high pressure systems, winds carryingcontinental, rather than oceanic air masses (i.e. reduced water content), and ridgesof high pressure areas form with behaviors which prevent or restrict the developingof thunderstorm activity or rainfall over one certain region.11. Global warming: Human activity can directly trigger exacerbating factors such asover farming, excessive irrigation, deforestation, and erosion adversely impact theability of the land to capture and hold water. While these tend to be relatively isolatedin their scope, activities resulting in global climate change are expected to triggerdroughts with a substantial impact on agriculture throughout the world, andespecially in developing nations.Overall, global warming will result in increased world rainfall. Along with drought insome areas, flooding and erosion will increase in others. 7. Drought7Paradoxically, some proposed solutions to global warming that focus on more activetechniques, solar radiation management through the use of a space sunshade forone, may also carry with them increased chances of drought.12. Decline in groundwater : India has seen a sharp decline in groundwater levels,leading to a fall in supply, saline water encroachment and the drying of springs andshallow aquifers. Around 50% of the total irrigated area in the country is nowdependent on groundwater, and 60% of irrigated food production depends on irrigationfrom groundwater wells.13. Depletion of forest : The rapid depletion of forest cover is also seen as one ofthe reasons for water stress and drought. India has a forest cover of 76 millionhectares, or 23% of its total geographical area much lower than the prescribedglobal norm of 33%. Although the scientific evidence is inadequate, forest-waterlinkages are widely acknowledged, especially the watershed functions of forests,greater availability of water, less soil erosion, more rainfall, flood and landslide control,etc.14. Rainwater harvesting : Combined with these and a host of other factors poorirrigation systems, pressure from the increasing industrial use of water is the appallingindifference displayed towards rainwater harvesting. Little has been done over theyears to drought-proof the country, when community based rainwater harvestingmeasures could easily accomplish this feat. 8. Drought8Co m m o n c a u s e s f o r i n I n d i aMeteorology Inadequate monsoon rainfall. High temperature & evaporation, wind speed. Unseasoned rains & fog / snowfall.Water Resources Inadequate water availability, high water loss in storage & distribution, utilities. Over exploitation of surface & ground water.Agriculture- Crop Yield Shift in agricultural practices(low to moderate water demand crops to high crops). Crop damage due to rain & snow / pest.Population High greater rate of human & animals. Location of high water consuming milestones at semi arid / arid regions. 9. Drought9 10. Drought10C l a s s i f i c a t i onPhysical aspects also used to classify drought. Theyclubbed into three major groups:MetrologicalAgriculture Hydrological 11. Meteorological-usually an expression ofprecipitations departure from normal over time.Agricultural Agricultural-Links various characteristics ofmeteorological or hydrological drought to agriculturalimpacts. precipitation shortages differences between actual and potential evapotranspiration soil water deficits, reduced ground water or reservoir levels.Drought11 12. Hydrological drought refers to deficiencies in surface andsubsurface water supplies. It is measured as streamflowand as lake, reservoir, and groundwater levels. There is atime lag between lack of rain and less water in streams,rivers, lakes, and reservoirs, so hydrologicalmeasurements are not the earliest indicators of drought. Although climate is a primary contributor to hydrologicaldrought, other factors such as changes in land use(deforestation), land degradation, and dam constructionalso contribute.Drought12 13. Drought13E f f e c t sE c o n o m i c :-Loss of national economicgrowth-slowing down of economicdevelopment.- Damage to crop quality, less food production.- Increase in food prices. 14. Drought14- Insect infestation.- Plant disease.- Loss from dairy and livestock production.-Unavailability of water and feed for livestock whichleads to high livestock mortality rates.- Disruption of reproduction cycles (breeding delaysor unfilled pregnancies). - Increased predation.- Range fires and Wild land fires. 15. Drought15- Damage to fish habitat, loss from fisheryproduction.- Income loss for farmers and others affected.- Unemployment from production declines.- Loss to recreational and tourism industry .- Loss of hydroelectric power.- Loss of navigability of rivers and canals. 16. Drought16S O C I A L:- Food shortages-Loss of human life from food shortages, heat,suicides, violence .- Mental and physical stress .-Water user conflicts.- Political conflicts.- Social unrest. 17. Drought17- Public dissatisfaction with governmentregarding drought response.- Inequity in the distribution of drought relief .- Loss of cultural sites.- Reduced quality of life which leads tochanges in lifestyle.- Increased poverty.- Population migrations 18. Drought18ENVIRONMENTEL 19. Drought19- Increased desertification - Damage toanimal species.- Reduction and degradation of fish andwildlife habitat .- Lack of feed and drinking water .- Disease .- Increased predation. 20. Drought20Case Study: Draught in Rajasthan 2002In the history of Rajasthan, the drought of 2002 was among the worstdroughts, caused by thefailure of the southwest monsoon in all the 32districts. All districts received scantyldeficientrainfall. Overall monsoonrainfall deficiency in Rajasthan in 2002 was (-) 65 percent, i.e. 65percent below normal, which was the lowest in the last 100 years. Inwestern parts of Rajasthan,the situation was worse with monsoon raindeficiency being 71 percent below normal.Relief MeasuresDrinking WaterAs all major sources of drinking water had dried up, a contingency plan of Rs. 5 18crore wasprepared and implemented to ensure supply of drinking water. 21. Drought21Wealth and NutritionAs against the normal seem of 1 00 beneficiaries per ' Aanganbari' ,100 percentcoverage of theage group of 0-6 years and expectant women was made in severely affectedblocksEmployment GenerationThe major thrust area in providing relief to about 38 million vulnerable peoplewas the employment generation specially for people below poverty line, small&d midium farmers and landless agriculturelabourers etc.Gratuitous ReliefIn the unprecedented situation, some vulnerable unemployed families i.e. about5 lakh people were provided foodgrains at the rate of 10 kg per person.Essential CommoditiesCattle conservation 22. Drought22Government policies to combatdroughtsCentral Arid Zone Research Institute (CAZRI)Rural Works ProgrammeDrought Prone Area Programme (DPAP) - labor intensive schemes such asmedium and minor irrigation, road construction, soil conservation and afforestactionDissemination of technologies relating to soil management, water harvesting,improved agronomic practices and drought-resistant crops CRIDADesert Development Programme (DDP)Integrated Watershed Management Programme rejuvenate depleted naturalresources on watershed basisNational Watershed Program for Rainfed Areas (NWSDPRA) 23. Drought23