Floods and its causes

Why is it that some places flood and others don’t? Here we investigate what causes floods. One area might receive a lot of rain and won’tflood while in other areas the same amount of rainfall can wreak havoc, destroying homes, businesses and the natural environment. Take the Boxing Day floods of 2015, for example. The north of England and Scotland saw thousands of homes and businesses wrecked and people forced to move and flee their homes. But why did it happen? Well, in the aftermath of the floods, teachers at Causes of floods Lead teacher Anil Sarna asked hislocal Year 5 and Year 6 pupils to see if they could work out what causes flooding, testing what they learnt using a series of experiments. Ask your teacher if you could try this experiment, too! “First, we discussed how features in a landscape can influence the way water descends from the high lands into valleys where flooding occurs,” Anil explained. –Trees maintain the soil structure, while deforestation increases erosion and makes the land less ‘permeable’ (less able to soak up water) – Straight rivers speed up water descent, while meandering ones slow it down – Plants hold the water back, while water rushes off concrete or paved built-up areas Anil and his team invited local kids to make model landscapes and experiment to see how much water collected in the ‘valleys’. Two tables were set up at 30° angles with waterproof bags at the bottom to collect water. Then a green fleece blanket was placed on on...

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. • Review Article • 10 August 2021 Causes, impacts and patterns of disastrous river floods • ORCID: orcid.org/0000-0002-5992-1440 • • ORCID: orcid.org/0000-0003-4639-7982 • ORCID: orcid.org/0000-0002-1388-3303 • ORCID: orcid.org/0000-0002-2162-5814 • • ORCID: orcid.org/0000-0002-5283-0386 • • • ORCID: orcid.org/0000-0003-0529-8128 • … • ORCID: orcid.org/0000-0003-0198-6556 Show authors Nature Reviews Earth & Environment volume 2, pages 592–609 ( 2021) Disastrous floods have caused millions of fatalities in the twentieth century, tens of billions of dollars of direct economic loss each year and serious disruption to global trade. In this Review, we provide a synthesis of the atmospheric, land surface and socio-economic processes that produce river floods with disastrous consequences. Disastrous floods have often been caused by processes fundamentally different from those of non-disastrous floods, such as unusual but recurring atmospheric circulation patterns or failures of flood defences, which lead to high levels of damage because they are unexpected both by citizens and by flood managers. Past trends in economic flood impacts show widespread inc...

Floods are the most common (and among the most deadly) natural disasters in the United States. They have brought destruction to every state and nearly every county, and in many areas they are getting worse. As global warming continues to exacerbate sea level rise and extreme weather, our nation’s floodplains are expected to grow by approximately What is a flood? A flood is the accumulation of water over normally dry land. It’s caused by the overflow of inland waters (like rivers and streams) or tidal waters, or by an unusual accumulation of water from sources such as heavy rains or dam or levee breaches. Major types of floods River Flooding This occurs when a river or stream overflows its natural banks and inundates normally dry land. Most common in late winter and early spring, river flooding can result from heavy rainfall, rapidly melting snow, or ice jams. According to one study, approximately Many factors can go into the making of a flood. There are weather events (heavy or prolonged rains, storm surge, sudden snowmelt), and then there are the human-driven elements, including how we manage our waterways (via dams, levees, and reservoirs) and the alterations we make to land. Increased urbanization, for example, adds pavement and other impermeable surfaces, alters natural drainage systems, and often leads to more homes being built on floodplains. In cities, under-maintained infrastructure can lead to urban flooding. More and more, flooding factors are also linked to clim...

Flooding results when water enters an area quickly and cannot drain, evaporate, or soak into the ground. There are many kinds of floods. Flash floods and river floods are the most common. A Dry climates and rocky terrain increase the risk of flash floods. This is because these conditions encourage torrential rainstorms to flow overland rather than seep into the ground. Greater runoff from prolonged rainstorms and occasionally from melting snow causes a slower rise in water level over a wider area. This makes Although ice jams on a river or high tides can also result in flooding, storms of some kind are usually to blame for most floods. Aside from these types of floods, several things can cause them. Earthquakes Indirectly, earthquakes can cause flooding in several ways, such as by setting off Also, parts of Japan’s coast dropped in height because of the quake, which cut up to three feet off the length of sea walls and protective levees. Barriers that were broken or lowered made the damage from the tsunami even worse. The The authorities relocated tens of thousands of people out of the valley because they were concerned. The risk and pressure on the vulnerable dam were then lessened over the course of three days as they decreased the water level in the reservoir. Most modern dams are constructed to withstand large earthquakes in seismically active regions, but anyone who lives in an area where a dam could flood needs to be aware of the risks and know how to evacuate. The 20...

A flood is a body of water that covers land which is normally dry. Floods are common natural disasters that can affect millions of people around the world. They destroy houses and buildings, and carry soil away from valuable farming land. Floods can also contaminate drinking diseases. They are often caused by overflowing lakes and seas can also cause flooding. Flooding has always been a part human history. Many ancient civilizations deve loped along waterways and rivers because people needed water for their fields. Floods are not always destructive natural events. Before the Assuan High Dam was built yearly floods in Egypt brought along nutrients and made the land around the fertile. Every year floods during the deposit fertile soil but also kill thousands of people and leave millions homeless. How do floods occur? At least once a year the plains around large rivers are flooded. This is due to the amount of water that rivers bring with them, because of heavy rainfall or melting snow in the mountainous regions. Thunderstorms can cause flash floods, in which small rivers can swell quickly and carry up to ten times the normal amount of water. Rivers that flow slowly carry water, sand and silt. They build up their own beds, making them higher than the land around them. The Huang He, or Yellow River, in China and the Mississippi in North America are examples for such rivers. Flooding here builds up slowly but causes more damage because more land is affected. Coastal regions can...