rivers form part of the water cycle - they are a downward flow of water, under the force of gravity
rivers shape the land through erosion, transportation and deposition - these create distinct landforms
in the upper course, vertical erosion creates waterfalls and v-shaped valleys
in the middle and lower courses, lateral erosion creates meander bends, oxbow lakes and deltas
the hydrological cycle, or water cycle, shows the movement of water between the atmosphere, land and oceans
energy from the Sun heats the surface of the Earth
water is evaporated from oceans, rivers, lakes
the warm, moist air rises because it is less dense
condensation occurs when water vapour is turned back into water droplets as it cools down
precipitation occurs as water droplets get bigger and heavier they begin to fall
surface runoff is water that flows on the surface of the ground
infiltration is when this water moves into the soil and rock layers below the surface
through flow is water that flows downhill within the soil
groundwater flow is water that flows downhill within rock layers under the soil
evapotranspiration - water moves from the land surface to the atmosphere via evaporation and transpiration
percolation - movement and filtering of fluids through porous materials
Waterfalls and rapids are found in the upper course. These form when rivers flow over hard and soft rock. Vertical erosion wears away soft rock, forming rapids and waterfalls
V-shaped valleys are found in the upper course. Vertical erosion lowers the level of the river channel. The bank either side are unsupported and so fall into the wate, leaving behind a v-shaped valley
Floodplains are found in the middle course - these are are flat areas of land either side of a river channel
there are many physical and human causes of river flooding, including heavy rainfall, steep surfaces and urbanisation
consequences of flooding include damage to property, loss of power and deaths
the impacts of flooding are often more severe in LICs
river floods can be managed using hard and soft engineering strategies - hard engineering strategies aim to control natural processes and soft engineering strategies work alongside natural processes
hard engineering: man made structures or approaches to reduce floodig
soft engineering: natural approaches to flood prevention
