geography

• channel straightening helps to reduce the risk of flood by enabling the water to be quickly sped away from vulnerable areas such as city's, which lowers the risk of a flood happening.
• Channel straightening is when a river's natural bends are removed to make it straight. This makes water flow faster, reducing flood risk nearby. However, it can cause flooding further downstream and damage the river's habitats.
• • Hard engineering: Big, strong structures like dams to control nature.
  • Dam: A wall across a river to hold back water.
  • Reservoir: A big, man-made lake behind a dam that stores water.
• Hard engineering is the use of artificial, human-made structures built to control the flow of rivers and reduce flooding. This is the traditional way that river flooding has been managed. 
• soft engineering uses natural processes to manage rivers rather than building large structures. It aims to restore rivers to their natural states and allow them to flood more often. Soft engineering is cheaper and less disruptive than hard engineering but may not work as well.
• Flooding occurs when the discharge in a river exceeds its bankfull capacity
• two reasons floods are becoming more severe are Increased precipitation intensity, a warmer atmosphere holds more moisture, leading to heavier rainfall and potential flash flooding.Sea level rise: This directly increases the risk of coastal flooding and storm surges during extreme weather events.
• two reasons for people to develop settlements on the floodplain are fertile land and accessibility. the main problem is the flood risks occurring with such land.
• the two physical factors that make flooding more likely are : Impenetrable ground and Steep slopes
• the two human factors that make flooding more likely are deforestation and urbanisation
• Floods happen when too much water overwhelms land, usually caused by heavy rain, overflowing rivers, or coastal storms.
• Soft engineering strategies aim to work with nature
• Soft engineering strategies

  Help to slow flows of water in the upper parts of drainage basins
• There is increasing focus on using soft engineering strategies
• The fastest way for rainwater to reach a river channel is through surface runoff. This happens when the ground is saturated, impermeable
• The slowest way for rainwater to reach a river channel is through infiltration and groundwater flow
• Groundwater flow - The movement of water underground from areas where it has entered the soil (recharge) towards areas where it leaves the soil (discharge)
• A shorter lag time means less time for water to soak into the ground or slowly flow through rivers. This faster water accumulation in the river channel increases the risk of overflowing and causing floods.
• the two physical factors influencing the shape of a hydrograph are discharge and lag time.
• the two human factors influencing the shape of a hydrograph are deforestation (cutting down trees ) and urbanization (land unable to soak water like roads )
• Flooding occurs when the peak discharge of a river exceeds its channel capacity
• drainage basin is An area where all rainfall flows into a single river.
• The volume of water flowing in a drainage basin depends on the amount of precipitation, the length of time over which this falls, and the permeability of the land surface.
• Transportation - Rivers transport sediment from one place to another, including rocks, sand, gravel, silt, and clay.
• Weathering - The breakdown of rock through chemical processes such as acidic rainwater dissolving minerals in limestone.
• Erosion - The process by which material is removed from an area due to weathering and erosive action.