The River Catchment Case Study: River Holford Flashcards
Where is the River Holford located?
The River Holford is in the Quantock Hills, Somerset, England.
What is the geology of the River Holford catchment?
The river sits on sandstone geology, which is impermeable, preventing percolation into the rock layer.
How does vegetation influence water movement in the River Holford catchment in upper slopes?
Maritime heather moorland, intercepting rainfall.
How does rainfall occur in the River Holford catchment? Give 2 steps
• Prevailing winds from the southwest bring moisture from the Atlantic.
• Relief rainfall occurs as air rises over the Quantock Hills.
How does water enter the River Holford?
Water flows from saturated soils at the source into a narrow, shallow channel.
What were the results of the infiltration fieldwork study near the river channel?
Infiltration rate was higher (2.15cm/min), suggesting most water reached the river through throughflow.
How does geology affect infiltration in the River Holford catchment in upper areas?
Permeable limestone, allowing greater infiltration.
Give 2 reasons why flooding is unlikely in the upper course of the River Holford?
• Water enters the river slowly through throughflow and soil water storage. (Since its sandstone)
• Steep slopes prevent long-term accumulation.
Give 2 reasons why Holford village in the middle course is prone to flooding?
• The gradient of the land is less steep.
• More impermeable surfaces (roads, houses).
How is flooding managed in the lower course at Kilve in 3 ways?
• The river flows through flat land and is carefully managed.
• Kilve village has flood defences to prevent flooding.
• The river forms a pool on the beach before reaching the sea at Kilve.
How long is the river?
It is 4.5 miles long and flows into the Bristol Channel at Kilve Beach.
How does vegetation influence water movement in the River Holford catchment in lower slopes?
Forested, allowing infiltration into peat soils.
What is the average annual rainfall in the River Holford catchment?
790-890mm.
What were the results of the infiltration fieldwork study further up the valley:?
Infiltration rate was lower (0.1cm/min), suggesting more surface runoff.
How does geology affect infiltration in the River Holford catchment in lower areas?
Permeable limestone, allowing greater infiltration.
Give an example of flooding in Holford Village
Flooding in February 2014 due to Storm Amber (heavy rain, 80mph winds).
