Drought, Student Seminar on Disaster Management, Bankura University, West Bengal, Dept of Geoinformatics, 2022.

Drought, Student Seminar on Disaster Management, Bankura University, West Bengal, Dept of Geoinformatics, 2022.

1. INTRODUCTION Low rainfall or failure of monsoon rain is a recurring feature in India. This has been responsible for droughts and famines. The word drought generally denotes scarcity of water in a region. Though, aridity and drought are due to insufficient water, aridity is permanent climatic feature and is culmination of a number of long-term processes.

2. DEFINITATION OF DROUGHT Early workers defined drought as period without rainfall. According to Ramdas (1960): Drought is a situation when the actual seasonal rainfall is deficient by more then twice the mean deviation. It is a period of below average precipitation in a given region, resulting in prolong shortage in the water supply, whether atmosphere, surface water or ground water. Drought is a period of inadequate or no rainfall over extended time creating soil moisture deficit and hydrological imbalance.

3. MAJOR DROUGHTS IN HISTORY THE DUST BOWL: ALSO KNOWN AS THE “Dirty Thirties,” the Dust Bowl period was the most destructive drought the United States has ever faced. According to the National Oceanic and Atmospheric Administration (NOAA), at least 50,000,000 acres of land were affected BENGAL FAMINE OF 1943: the Bengal famine of 1943was a major famine of the Bengal province in British2 million, out of a population of 60.3 million, died of starvation, or of malaria and other diseases aggravated by malnutrition, population displacement, unsanitary conditions and lack of health care.  

4. ETHIOPIAN FAMINE (1984 TO 1985) Widely televised throughout the west, the Ethiopian famine put five million people at risk of starvation when a 1981 drought wiped out crops. The 1984 harvest did not yield nearly enough crops to feed the population, and a fam quickly took hold.

5. CAUSE OF DROUGHTS LACK OF RAINFALL GLOBAL WARMING EL-NINO DRY SEASON HUMAN ACTIVITIES

6. TYPES OF DROUGHTS Permanent drought Seasonal drought Contingency drought Invisible drought Metrological drought Slight Moderate sever Hydrological drought Agriculture drought Socio-economic drought Early season drought Mid season Drought Late season / terminal drought Chronic drought Apparent Drought Soil Drought Atmospheric Drought 1.Based on duration 2. Based on source of water availability/relevance to the user 3. Based on time of occurrence 4. Based on medium

7. EFFECT OF DROUGHTS One can divide the effects of drought and water shortages into three groups: Environmental Economic Social

8. Environmental In the case of environmental effects: lower surface and subterranean water-levels, lower flow-levels (with a decrease below the minimum leading to direct danger for amphibian life), increased pollution of surface water, the drying out of wetlands, more and larger fires, higher deflation intensity, loss of biodiversity, worse health of trees and the appearance of pets and dendroid diseases.

9. Economic Economic losses include lower agricultural, forests, game and fishing output, higher food-production costs, lower energy-production levels in hydro plants, losses caused by depleted water tourism and transport revenue, problems with water tourism and transport revenue, problems with water supply for the energy sector and for technological process in metallurgy, mining, the chemical, paper, wood, foodstuff industries etc. Disruption of water supplies for municipal economics.

10. Social Social cost includes the negative effect on the health of people directly exposed to this phenomenon (excessive heat waves), possible limitation of water supplies, increased pollution levels, high food-costs, stress caused by failed harvests, etc. this explains why droughts and fresh water shortages operate as a factor which increases the gap between developed and developing countries.

11. State District Andhra Pradesh Anantapur, Chittoor, Cuddapah , Hyderabad, Kurnool, Mehaboobnagar , Nalgonda and Prakasam Bihar Munger, Nawadah, Palamau , Rphtas , Bhojpur , Aurangabad and Gaya Gujarat Ahmedabad, Amrely , Banaskanta , Bhavanagar , Bharuch, Jamnagar, Kheda, Kutch, Meshana , Panchmahal , Rajkot and Surendranagar Haryana Bhiwani, Gurgao , Mahendragarh and Rohtak Jammu and Kashmir Doda and Udhampur Karnataka Bangalore, Belgaum, Bellary, Bijapur , Chitradurga , Chickmangalur , Dharwad, Gulbarga, Hassan, Kolar, Mandya , Mysore, Raichur and Tumkur Madhya Pradesh Betul , Datia , Dewas , Dhar, Jhabuva , Khandak , Khargaon , Shahdol , Shahjapur , Sidhi and Ujjain Maharashtra Ahmednagar, Aurangabad, Beed, Nanded, Nashik, Osmanabad, Pune, Parbhani , Sangli , Satara and Sholapur Odisha Phulbani, Kalakhandi , Bolangir and Kendrapada Rajasthan Ajmeer , Banaswada , Barmer , Churu, Dungarpur, Jaisalmeer , Jalore , Jhunjhunu, Jodhpur, Nagaur , Pali and Udaipur Tamil Nadu Coimbatore, Dharmapuri, Madurai, Ramanathapuram , Salem, Tiruchirapalli , Tirunelveli and Kanyakumari Uttar Pradesh Allahabad, Banda, Hamirpur, Jalaun, Jhansi, Mirzapur and Varanasi West Bengal Bankura, Midnapur and Purulia Table:- Administrative districts frequently affected by drought

12. Digital Indices for Agricultural Drought Assessment: Different types of drought require different indices that can be used to quantify the moisture condition of a region and thereby detect the onset and measure the severity of drought events, and to quantify the spatial extent of a drought event thereby allowing a comparison of moisture supply condition between regions. It has become clear that no single indicator or index is adequate for monitoring drought on regional scale. Instead, a combination of monitoring tools integrated together is preferable for producing regional or national maps. Thus, spatiotemporal patterns of seasonal drought can be detected using meteorological, vegetative as well as crop performance indices among others.

13. Normalized Difference Vegetation Index: NDVI is an index of vegetation health and density and computed from the satellite Image using spectral radiance in red and near infrared reflectance using the formula(eq.1): NDVI= (NIR-R) / (NIR+R) equation (1) Where, NIR= near infrared band, R= Red band Vegetation Condition Index: Kogan (1990) developed Vegetation Condition Index (VCI) using the range of NDVI which is a good indicator for assessing the severity of agricultural drought. It is defined as(eq.3): VCI = (NDVI-NDVI Min) / (NDVI Max-NDVI Min)*100 equation (3) Where, NDVI is the actual value of NDVI , NDVI max and NDVI min are smoothed weekly NDVI absolute maximum and its minimum. Temperature Condition Index: TCI is also suggested by Kogan(1997). It was developed to reflect vegetation response to temperature i.e. higher the temperature more extreme the drought. TCI is based on brightness temperature and represents the deviation of current month’s value from the recorded maximum. It is defined as(eq.4): TCI = (BT Max-BT) / (BT Max-BT Min)*100 equation (4) Where, BT, BT max and BT min are smoothed weekly brightness temperature absolute maximum and its minimum.

14. COMMOM CONSEQUENCE OF DROUGHT : HUNGER AND FAMINE Drought conditions often provide too little water to support food crops, through either natural precipitation or irrigation using reserve water supplies. When drought undermines or destroys food source, people go hungry. When the drought is severe and continues over a long period, famine may occur. NOT ENOUGH DRINKING WATER All living things must have water to survive. People can live for weeks without food. But only a few days without water. When desperate for water to drink, people will turn to untreated sources that can make them sick.

15. DISEASE: Drought often creates a lack of clean water for drinking, public sanitation and personal hygiene, which can lead to a wide range of life-threatening diseases. The problem of water access is critical every year, millions are sickened or die due to lack of clean water access and sanitation, and droughts only make the problem worse. WILDLIFE: Wild plants and animals suffer from droughts, even if they have some adaptations to dry conditions. In grasslands, sustained lack of rain decreases forage production, affecting herbivores, grain-eating birds, and indirectly, predators and scavengers.

16. Thank You