FLOODING An Environmental Management Presentation
What is a flood? • A flood is an overflow of an expanse of water that submerges land. • The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water.
What causes flooding? • Rain is usually a flood’s main cause.
What causes flooding? • Tropical monsoon climate that have a high average annual rainfall.
Tropical cyclones that bring rain-water. What causes flooding?
What causes flooding? • Relief, that is, the configuration of the country. If the country is near the coast, lies low above sea level or on a flood plain or delta, it will have heavy rains that may cause flood.
What causes flooding? • Drainage, or the amount of water the rivers and lakes can hold and the amount of water present in these bodies when the country is not experiencing flood.
What effects does it have? Its effects can be • Immediate • Short-term • Long-term
Immediate: Loss of lives from the force of the flood water. Many people drown. What effects does it have?
Immediate: Destruction of property, again from the water and force of the flood. What effects does it have?
Immediate: Destruction of crops, plants, trees, and livestock. What effects does it have?
What effects does it have? • Immediate: Destruction of natural habits which may lead to the death of valuable species of animals.
Immediate: Disturbance of communication. What effects does it have?
What effects does it have? • Short-term: Need of medical treatment and breakout of water-related diseases.
Short-term: People are made homeless. What effects does it have?
What effects does it have? • Short-term: Shortage of food and safe drinking water.
What effects does it have? • Short-term: Problems of moving.
What effects does it have? • Long-term: Rebuilding, repairing, restoring and replacing houses, bridges, railway lines and essential public services like water and sewerage.
What effects does it have? • Long-term: Reclaiming farm-land and buying new seeds and animals.
What can be done? • Constructing dams to store water so that water that can help flood can be held back and, in addition, electricity produced.
What can be done? • Constructing reservoirs so that water can be stored and then later used for agriculture if desired. This, however, does not produce electricity.
What can be done? • Constructing strong coastal embankments so that not too much water spills out from the water body. The river embankments should also be increased in height to help it carry water.
Anything cheaper? • Dredging, that is, removing the excess sediments at the bottom of the river so that the river is able to carry more water for itself.
Anything cheaper? • Better flood forecasting and warning schemes, so that people can be aware and well-prepared for what is to come.
Anything cheaper? • More flood shelters so people can stay somewhere safe at the time of flood.
Anything cheaper? • Better prepared emergency services, so that more people in trouble can be saved.
Flood brings us sediments and water which are very important for agriculture. The sediments can act as fertiliser. Any good sides of flood?
What is a flash flood? • A flash flood is a rapid flooding of geomorphic low-lying areas – washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or melted water from ice or snow flowing over ice sheets or snowfields.
Some more flood prevention • In many countries across the world, rivers prone to floods are often carefully managed. Defences such as levees, bunds, reservoirs, and weirs are used to prevent rivers from bursting their banks. When these defences fail, emergency measures such as sandbags or portable inflatable tubes are used. Coastal flooding has been addressed in Europe and the Americas with coastal defences, such as sea walls, beach nourishment, and barrier islands.
The 1998 Bangladesh flood • In September 1998, Bangladesh saw the most severe flooding in modern world history. As the Brahmaputra, the Ganges and Meghna spilt over and swallowed 300,000 houses, 9,700 kilometres of road and 2,700 kilometres of embankment 1,000 people were killed and 30 million more were made homeless with 135,000 cattle killed, 50 square kilometres of land destroyed and 11,000 kilometres of roads damaged or destroyed. Two-thirds of the country was underwater. There were several reasons for the severity of the flooding. Firstly, there were unusually high monsoon rains. Secondly, the Himalayas shed off an equally unusually high amount of melt water that year. Thirdly, trees that usually would have intercept rain water had been cut down for firewood or to make space for animals.
The 1998 Bangladesh flood • Bangladesh is now widely recognised to be one of the countries most vulnerable to climate change. Natural hazards that come from increased rainfall, rising sea levels, and tropical cyclones are expected to increase as climate change, each seriously affecting agriculture, water & food security, human health and shelter. It is believed that in the coming decades the rising sea level alone will create more than 20 million climate refugees. Bangladeshi water is contaminated with arsenic frequently because of the high arsenic contents in the soil. Up to 77 million people are exposed to toxic arsenic from drinking water. Bangladesh is among the countries most prone to natural floods, tornados and cyclones.
Are we increasing floods? • Human activity can increase the risk of flooding. For example, clearing forests and replacing them with urban areas is responsible for the increased flood risk in many towns and cities located in valleys. This can become is a major problem in Bangladesh. Global warming is helping to increase flood. It is also causing the sea-level to increase rapidly. If it continues, a lot of the country will become submerged under water. A flood at that time would be catastrophic. So, we should do anything necessary to stop global warming, as it will definitely destroy Bangladesh if we do not.
THE END Thank You For Watching
Prepared By: Abidur Rahim Roll: 207 Sec: I Class: 8 Teacher: Mohammad Yakub (MY) ‘O’ Level Course Coordinator of Environmental Management Credits