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Wind and Water-Related Natural Disaster: Floods

by | Apr 16, 2022 | Disaster Management

Introduction

Water-related disasters like floods, cyclones, landslides, waves, and surges will pose an ever-increasing danger to vulnerable populations, and sustainable development as climate change increases the frequency and intensity of extreme weather.

Wind storms can form when warm and cold winds collide over the ocean after a rainstorm or when different zones of wind pressure hit. Storms with winds above 119 kilometres per hour are known as cyclones, hurricanes, and typhoons (74 MPH). On average, 80-100 of these storms strike each year, and while only a small percentage of them make landfall, the ones that do may wreak massive damage.

Water-related disasters have direct and indirect consequences, such as damage to structures, crops, and infrastructure and casualties of life and property. Losses in production and livelihoods, increased investment risk, indebtedness, and human health effects are some of the indirect effects.

Floods, droughts, and intense storms are examples of water and wind-related hazards that can lead to disasters when people or economic commodities are exposed to them, and there is insufficient preparedness. Floods harm the most people each year, affecting around 77 million people. Floods also cause the most economic damage, with an estimated yearly cost of $9.25 billion. Landslides, subsidence, wildfires, and saltwater intrusion are all secondary water and wind threats.

Floods

Floods are the most common natural catastrophe, and they occur when a large amount of water overflows and submerges normally dry terrain. Injuries or deaths might result from failing to flee flooded regions or entering flooding. Floods can occur when heavy rains fall, ocean waves crash on the beach, snow melts fast, or dams or levees fail.

Causes of Flooding

Floods in coastal locations are frequently produced by heavy rainfall, quick snowmelt, or a storm surge from a tropical cyclone or tsunami. In minutes, an area can get flooded, or it can be for over a lengthy period, lasting days, weeks, or even months. Atmospheric conditions that contribute to heavy rain or quick melting of snow and ice generate severe floods. A flood can be caused by a variety of factors. Here are a few examples:

  • Extreme rainfall
  • Oncoming waves from the sea, such as a storm surge
  • Ice jams caused by melting snow and ice
  • Breaking of dams or levees

Hazards Associated with Flooding

Floods have a variety of consequences. Floods may create havoc in communities. It can cause damage to properties, important public health infrastructure, and even deaths. Floods impacted almost 2 billion people globally between 1998 and 2017. There have been cases of human and cattle deaths and illness epidemics. Floods can be seriously dangerous to people living in floodplains or structures that aren’t flood-resistant, don’t have flood warning systems, or aren’t aware of the danger. Massive levels of erosion can be caused by floodwaters. Bridges, levees/dykes, and structures can all be weakened and undermined by erosion, resulting in their collapse.

Food supplies and help may be delayed as a result of disruptions in transportation, electrical, and fuel infrastructure. In less developed countries, this has led to hunger.

Flood Forecasting

Flood forecasting is the practice of estimating and predicting the amount, timing, and intensity of flooding based on known features of a river basin to avoid harm to human life, property, and the environment. Flood forecasting is an essential instrument for lowering vulnerabilities and flood risk and an essential component of the life with floods approach, which contributes to long-term national development. The accessibility of accurate and timely meteorological and hydrological forecasting is very crucial. All weather-related services and reporting to authorities responsible for civil protection and the general public would have been critical to the various national disaster management authorities’ preparedness and response actions.

Flood Management 

All strategies employed to limit or prevent the negative consequences of floodwaters are referred to as flood management. Installation of rock berms, rock rip-raps, sandbags, preserving normal slopes with vegetation or applying soil cement to steeper slopes, and building or enlargement of drainage systems are all frequent flood control strategies.

Flood risk assessment and mapping to identify flood-prone regions and risk particular such studies can assist in reducing flood damage by regulating land use and urban development, therefore preventing the siting of necessary infrastructure.

Forecasting and flood warning systems monitor weather and aid in damage reduction by informing people to evacuate or prepare themselves, safeguard their valuables, and floodproof their homes and other infrastructures before a flood occurs. Urban and agricultural communities, residences, and other economically significant regions and the people who live there can be protected by flood management systems.

Database on floods – https://eartharxiv.org/repository/object/1722/download/3728/

 

 

Floods

Droughts

A drought is when a region or area receives less rain than usual. Decreased soil moisture or groundwater, reduced streamflow, agricultural damage, and general water scarcity are several problems resulting from inappropriate precipitation, whether heavy rain or snow. Droughts, after hurricanes, are the most expensive weather occurrences.

Droughts affect an estimated 55 million people worldwide each year. It poses a significant threat to biodiversity, animals and crops in practically every corner of the globe. This kind of disaster endangers people’s livelihoods, raises illness and death risks, and encourages mass migration. Water shortage affects 40 per cent of the world’s population, with up to 700 million people in danger of being displaced by drought by 2030.

Droughts have a variety of effects on individuals. All life needs clean drinking water, and water supplies may be depleted during a drought. People must bring in enough water from somewhere to survive if there is no water. Water is also required for the growth of crops. When there isn’t enough rain to water crops naturally, they must be irrigated using irrigation. Irrigation is only possible if there is sufficient water in adjacent rivers, lakes, or streams or if groundwater is available. These water sources are depleted and may even dry up during a drought, preventing crops from being watered and leading them to perish.

Because of rising temperatures at high levels brought on by climate change, existing dry regions become dryer, while wet ones become wetter. In arid locations, this implies that water evaporates more quickly when temperatures rise, increasing the danger of drought or prolonging drought spells.

Cyclones

Cyclones are a vast system of winds that rotates in a counter-clockwise manner north of the Equator and in a clockwise way south of the Equator around a low atmospheric pressure centre. Cyclonic winds are potent winds. With the exception of the equatorial belt, these winds travel across all of the Earth’s surface. The cyclonic winds are usually bringing rain or snow.

When we talk about the types of cyclones, these are of two kinds – Tropical cyclones and medium latitude (mid-latitude) cyclones. Medium latitude cyclones mainly cause winter storms in the middle latitudes. Hurricanes are the name given to tropical cyclones.

Mid-latitude Cyclone

When the temperature difference between two air masses is large, mid-latitude cyclones, also known as extratropical cyclones, occur near the polar front. As they pass each other, these two masses of air blow in opposite directions. In the Northern Hemisphere, the Coriolis Effect deflects winds to the right, forcing winds to strike the polar front at an angle.

Tropical Cyclone

Tropical cyclones go by a variety of names. In the North Atlantic and eastern Pacific oceans, they are known as hurricanes, typhoons in the western Pacific, tropical cyclones in the Indian Ocean, and will-in Willi are the waters surrounding Australia. They are the most destructive storms on the planet, regardless of their name. In the summer and fall, when the temperature of the sea surface rises to 28 ℃ (82 ℉) or greater, in these conditions’ hurricanes form in tropical latitudes (between 10 and 25-degrees N). A vast humid air mass is created by the warm oceans. Warm air rises and produces a tropical depression, which is a low-pressure storm.

https://public.wmo.int/en/our-mandate/focus-areas/natural-hazards-and-disaster-risk-reduction/tropical-cyclones

Tsunamis

Tsunamis are a sequence of massive waves caused by an undersea disturbance such as an earthquake, volcanic eruption, landslide, or meteorite (often referred to as “tidal waves”). A tsunami may travel hundreds of miles per hour in the open ocean and hit land with waves of 100 feet or more.

The height of Tsunami waves does not drastically increase as they move further into the ocean. Soon as the depth of the water declines, the waves rise to greater and higher heights as they go onshore. The speed of tsunami waves is generally measured by the depth of the water rather than the distance from the wave’s source. Tsunami waves are fast-moving. They may move as rapidly as jets across deep water. They stop down only when they reach shallow water. Tsunamis are frequently referred to as tidal waves. It is the wrong terminology by oceanographers. This is because tides have nothing to do with the massive waves of tsunamis.

Waves move outward in all directions from the point where the tsunami began. As the wave gets closer to the coast, it gets bigger. The magnitude of the wave will be influenced by the geography of the shoreline and the ocean floor. There might be more than one wave, and each one could be bigger than the one before it. That’s why a minor tsunami on one beach might turn into a massive wave just a few kilometres elsewhere.

Tsunamis are all potentially destructive, even if they may not cause damage to every shoreline they hit. A tsunami may strike almost anywhere along the shoreline.

 

Author

  • The author has done a master's in Environmental science and is currently working as chief Environmental Advisor with New Delhi State Government.

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