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Pickering Beck (river catchment) case study - Coggle Diagram
Pickering Beck (river catchment) case study
Flood Management
As one third of the land in the catchment is in public ownership , it has been easy to change aspects of the catchment.
Low level bunds at Newtondale mean water can be stored in the upper catchment until discharge decreases.
The scheme to reduce flood risk in Pickering has adopted a policy called 'Slowing the Flow', aiming to reduce peak flow through Pickering using land management techniques.
Riparian woodland of hydrophilic plants, e.g. alder and willow has been planted in strips 30 m wide on either side of the Beck. This creates a water stored and encourages infiltration.
The scheme aimed to reduce flood risk, increase biodiversity, water quality and community involvement.
Moorland drains have been blocked with heather bales, encouraging natural storage within moorland and reducing low to the Beck.
Physical geography of catchment and location and impact on water cycle
Upland areas such as the large, flat moorland plateaus in the north of the Pickering Beck catchment receives large amounts of precipitation in a short time as a result of relief rainfall.
Steep valley side within the catchment make it vulnerable to flash flood following heavy downpours during gummer convectional rain. Water fails to infiltrate leading to surface runoff and flooding.
After long periods of antecedent rainfall groundwater and soil moisture storage can become saturated resulting in surface runoff and flooding.
For these reasons, discharge does not tend to be 'flashy' within the catchment.
The large catchment of 68km2 consists of gritstones and limestones (permeable rock) which means precipitation can infiltrate and percolate, creating underground stores of water.
The flat valley floor at Pickering allows water to spread out, thus flooding a wider area.
Near its source, the land use pf the Pickering Beck catchment is moorland, e.g. Saltergate Moor and Levisham Moor.
There are a number of tributaries such as Gundale Beck which add water to the main river.
Location
Pickering Beck is located in North Yorkshire, north east of Leeds and York.
It is found in North York Moors National Park.
Pickering Beck is a tributary of the River Derwent.
Flooding
The beck flows through Pickering town centre which flooded in 1999, 2000 and 2007.
In 2007, 85 properties and the A170 (main route through town) flooded, which disrupted tourism in the NYMNP, deliveries and peoples' lives. The access to marketplace was restricted with a resultant loss of earnings.
The 2007 flood affected the whole of the Yorkshire and Humber region where the total damage was estimated at £2.1 billion
Human activities affecting flooding
Urbanisation: the market town of Pickering (population of 7000) is found to he south of the catchment and the main A170 passes through the town. Impermeable surfaces and artificial drainage increase discharge and reduce store. It also means deforestation.
Arable land use in the lower catchment means natural covering vegetation has been removed. Soil between crops can be eroded during heavy rainfall, e.g. particularly slopes.
Soil erosion leads to siltation: soil is transported to river channels where it reduces the possible water volume, encouraging flooding.
Agricultural land use has been responsible: pastoral farming has resulted in overgrazing. Loss of vegetation by grazing animals removes a water store, leaving soil vulnerable to erosion. Trampling by livestock can compact soil, reducing infiltration or churn soil up encouraging eorion.
Drainage of moorland has reduced the river catchments' natural water storage capacity. Moors and the peat soil beneath act as a sponge, soaking up cast amounts of precipitation and releasing it slowly into becks and streams. Draining moorland artificially causes water to get to the river more quickly.