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neurologyYou need to know

• The water cycle is the continuous movement of water between the Earth's surface, atmosphere, and oceans.
• Water changes state in the hydrological cycle through evaporation, condensation, and freezing or melting.
• Evaporation is the process where liquid water is heated and changes into water vapour.
• Condensation is the process where water vapour cools and changes into liquid droplets, forming clouds.
• Precipitation is water falling from the atmosphere to the Earth's surface as rain, snow, sleet, or hail.
• A river is a moving body of water that flows downhill from high land to low land in a channel.
• A drainage basin is the area of land drained by a river and its tributaries.
• A watershed is the highland boundary that separates one drainage basin from another.
• The main parts of a river system are the source, channel, tributary, confluence, mouth, drainage basin, and watershed.
• A river's upper course usually has a steep gradient, a narrow, shallow channel, vertical erosion, and landforms such as waterfalls and gorges.
• A river's middle course usually has a gentler gradient, a wider, deeper channel, more discharge, lateral erosion, and landforms such as meanders.
• A river's lower course usually has a very gentle gradient, a wide, deep channel, high discharge, deposition, and landforms such as floodplains, levees, and deltas.
• River erosion is the wearing away of the river bed and banks by the force of water and the sediment it carries.
• The four types of river erosion are hydraulic action, abrasion, attrition, and solution.
• Hydraulic action is erosion caused when the force of water compresses air into cracks in rock, causing the rock to break apart.
• Abrasion is erosion caused when sediment carried by the river scrapes and wears away the bed and banks.
• Transportation is the movement of sediment by a river, and deposition is the dropping of sediment when the river loses energy.
• The four types of river transportation are traction, saltation, suspension, and solution.
• Deposition is when material is dropped as the river loses energy.
• Waterfalls form where hard rock overlies soft rock.
• Plunge pools form through abrasion and hydraulic action.
• Undercutting causes the overlying rock to collapse, making the waterfall retreat.
• Repeated collapse and retreat of a waterfall form a steep-sided gorge.
• Meanders form where on the outer bend, fast-flowing water causes erosion, forming a river cliff, while on the inner bend, slower water leads to deposition, creating a slip-off slope; over time, the meander neck narrows until the river cuts through, leaving behind a cut-off meander known as an ox-bow lake.
• Flooding is when water covers land that is normally dry.
• Natural causes of flooding include heavy rainfall, snowmelt, impermeable geology, and steep relief, while human causes include urbanisation, deforestation, and building on floodplains.
• Hard engineering methods, such as dams, levees, channelisation, and flood walls, provide immediate flood protection but are often expensive, whereas soft engineering approaches, such as afforestation and flood warnings, aim to reduce flood risk more sustainably in the long term.

• Describe the water cycle by sequencing evaporation, condensation, cloud formation, precipitation, and the return of water to rivers, oceans, or groundwater.
• Label the key parts of a river system accurately, including source, tributary, confluence, channel, mouth, drainage basin, and watershed.
• Compare the upper, middle, and lower courses of a river using gradient, channel shape, velocity, discharge, erosion, transportation, and deposition.
• Explain the formation of a waterfall step by step, including hard rock over soft rock, erosion of soft rock, plunge pool formation, undercutting, collapse, and gorge retreat.
• Classify river transportation processes by matching sediment size to traction, saltation, suspension, or solution.
• Explain meander formation by linking faster flow and erosion on the outer bend to slower flow and deposition on the inner bend.
• Explain ox-bow lake formation by sequencing meander neck narrowing, cut-through during high flow, deposition sealing the old channel, and lake isolation.
• Explain the formation of floodplains and levees by linking lower-course meandering, lateral erosion, overbank flooding, and repeated deposition.
• Evaluate flood management strategies by comparing hard engineering and soft engineering in terms of cost, speed of protection, environmental impact, and sustainability.
• Assess the Somerset Levels flood case study by linking causes, impacts, management responses, and their effectiveness in reducing future flood risk.