Edexcel B GCSE Geography > The UK’s Evolving Physical Landscape > The influence of climate, geology and slope processes on river landscapes and sediment load
A range of physical factors, including climate, geology, and slope processes, shape river landscapes. These same factors also help explain the characteristics of storm hydrographs, which show how a river responds to a rainfall event. The speed and volume of water flow, along with sediment load, are all linked to the physical geography of a drainage basin.
Climate and River Landscapes
Climate plays a significant role in shaping river systems:
Rainfall intensity and frequency influence the amount of water in a river. Areas with high rainfall tend to have greater discharge, more erosion, and a higher sediment load.
Storm events can cause flash floods, leading to rapid erosion and transportation.
In cold climates, freeze-thawweathering can break down rock, increasing sediment supply.
High temperatures increase evaporation, reducing water flow and sediment movement.
Geology and River Features
Geology influences how rivers erode the landscape:
Hard, resistant rocks like granite form steep-sided valleys, waterfalls, and rapids because they erode slowly.
Soft rocks such as clay and shale erode easily, forming wide valleys and meanders.
Permeable rocks like chalk allow water to soak in, reducing surface runoff, whereas impermeable rocks like slate increase runoff, affecting river discharge.
Slope Processes
Slope processes affect the shape of valleys and sediment supply:
Mass movement (sliding, slumping, soil creep) can add material to rivers.
Steep slopes encourage rapid surface runoff, leading to increased erosion and a higher sediment load.
Gentle slopes slow down water flow, promoting deposition.
Sediment Load
Sediment comes from:
Weathered rock and mass movement on valley sides
Erosion from river processes like abrasion and hydraulic action
Human activity, such as deforestation or farming (though this is human, not physical)
The size and amount of sediment depend on:
Rock type – soft rock provides more material
Gradient – steep slopes increase erosion and material movement
Climate – heavy rainfall and freeze-thaw weathering both contribute to increased sediment
Summary
Climate and Rivers
High rainfall and intense storms increase river discharge and erosion, resulting in increased sediment transport and deposition.
Rock Type Matters
Hard rocks like granite create steep valleys, while soft rocks erode more easily, shaping wider river valleys and contributing more sediment.
Permeability of Rocks
Permeable rocks (e.g. chalk) allow water to soak in, reducing surface runoff, whereas impermeable rocks (e.g. clay) increase runoff and flood risk.
Slope Processes
Steeper slopes increase runoff and erosion, while gentle slopes promote slower movement and more deposition along the river.
Mass Movement
Processes like soil creep, slumping and landslides add rock and soil to rivers, increasing the sediment load and influencing channel shape.
Sediment Load Sources
Sediment comes from weathering, erosion, and slope processes, and varies in size depending on slope, geology, and climate.
