River flooding LS: Explain the soft and hard strategies of reducing flood risk. Write a case study for a flood event in an MEDC and LEDC and explain the differences.

Introduction to flooding Flooding mostly occurs in the lower course of a river where there is wide flat land – the flood plain, flooding can occur for many different reasons: Heavy rainfall Relief patterns Rock types – impermeable and permeable Weather conditions – wet conditions Prolonged rainfall – continuous rainfall for 2-3 days Snow and ice melt Human factors: Deforestation – the removal of trees = less interception storage Building material – buildings built from impermeable surfaces, increase run-off into river.

Impacts of flooding The impacts of flooding vary from LEDCs to MEDCs Flooding has primary and secondary impacts. The result of these impacts vary from LEDC to MEDC regions, case studies of flood events can show the outcome of impacts from flooding.

MEDC Flood event – Case Study Lynmouth Devon ) No early flood warning, due to lack of modern technology, the area suffered heavy rainfall over a long period of time. There was 1.75cm rain per hour, and rapid run off into V-shaped valleys. The ground is also saturated which means the soil absorbs water quickly and the water is transported to rivers 2) impacts: Caused 34 deaths 1000 people left homeless. 90 buildings were destroyed 150 total of lost transport.

LEDC Flood event – Case Study Mekong Delta Floods, 2000 V-Shaped valleys in Laos and Cambodia received heavy rainfall for a few days. The monsoon season was above average for 3 years, so the ground was very saturated. Deforestation and building with impermeable rock increased run-off. Impacts of flood: 350 people died, mostly young children. Hundreds of thousands forced to leave there homes in June to occupy small muddy banks. There was no return to the villages until December. No reserve food supply, people died from starvation. People relied on relief workers to bring food. Crops were lost such as rice. A plague of golden water snails threatened all surviving crops. Diseases spread from contaminated water.

Flood management – Hard Engineering Floods are managed and controlled by two different strategies: Hard engineering and Soft engineering. Hard engineering strategies are strategies which concentrate on the rivers physical features, which prevent further flooding. -Straightening river channels prevents flooding as rivers are no longer meandering and are flowing in straight flows. -Man-made levees, builders place man-made embankments in place to hold the capacity of water in the river and reducing the impact of flooding. -Building dams and artificial reservoirs, building dams keep water stored and lets water through in stages, reservoirs are man-made lakes to hold water behind dams, so instead rivers flow into the reservoirs. Hard engineering comes with a price, you don't get all these for nothing, they are very expensive and not to mention harmful to the environment, example Dams are being built in China which are wiping out ecosystems.

Soft engineering Soft engineering strategies are strategies not to prevent flooding, but to prevent the impacts and effects of flooding, this is done in several ways. -Weather forecasts and warnings, people are warned about the flood events and can prepare for the flood. -Preparation, when people have been warned they can prepare and evacuate the area, sometimes these two methods do not work because it may be too late. -Flood plain zoning, people that live in flood plain areas are restricted to move away from the area, or live further away from the river. -doing nothing, people accept the risks and live in flood livelihood, reasons people may not move away of leave is because of living near to family or there love for the area. Soft engineering has got some disadvantages though, it doesn't prevent flooding and can still effect people, especially those in LEDC and developing countries where the technology of warnings and no preparation is not in place. Which is more sustainable? Soft engineering is more sustainable than hard engineering, though it does not prevent flooding, it can reduce the impacts of flooding, hard engineering harms the environment is expensive, soft engineering doesn't do any of that.