RIVER TEES

human activity

summary

how are geomorphic processes affected

positive impacts on the landscape

negative impacts on the landscape

reservoirs

9 of them

upper course reservoir called Cow Green → 41 million m²

Reservoirs trap sediment behind the dam walls and limit the transport of the load of material down the river. This can starve downstream river locations of sediment.

 

Water released from the reservoir also has more energy to erode as it is not carrying sediment. Therefore we find increased erosion just below the dam (channel scour).

 

By managing the outflow of water from the reservoir, this limits the amount of flooding downstream, reducing the deposition of fertile alluvium on to the floodplains. A more regular flow of water reduces erosion (in times of natural high flow) and deposition (in times of natural low flow).

  • Control of flooding for downstream communities (good for people and critical urban infrastructure)

  • Recreation opportunities on/around the reservoirs (boating, fishing, camping)

  • New habitats for aquatic species

  • Water storage can aid climate resilience, assisting during droughts

  • Control of flowing for downstream agriculture - starved of fertile deposits

  • Fish populations may lose easy migration routes upstream

  • Sedimentation behind the dam reduces fertility of downstream agricultural areas and also reduces the efficiency of reservoirs over time

  • Drowning forestry can be bad for climate emissions

The Tees Barrage

opened in 1995

cost £50 million

70m wide

When there are high tides and/or low pressure weather systems, sea water can come up the river and by closing the barrage, upstream settlements can be saved.

 

This stops flood events upstream along the river, reducing transport and then deposition of sediment on the floodplains

  • Recreation opportunities on/around the reservoirs (white water rafting course set up alongside the barrier)

  • Fish ladders have been installed to reduce the impact on migrating fish and fluvial ecosystems

  • Positive economic impact on surrounding area with white water rafting centre created.

  • Aesthetically unappealing

  • Barrier needs constant management to ensure there are no man-made disasters (e.g. barrier being shut in heavy rainfall would cause flooding around the barrier as water accumulated)

  • Reduction of flood events means fertile river alluvium does not help fertilise agricultural land

Afforestation

The Tees Catchment Partnership are in charge of managing the river and land around the Tees. They do lots of environmental practices, including afforestation.

Lots of the afforestation projects are in upland environments.

Vegetation binds soils and prevents erosion occurring. Afforestation therefore is good at protecting the landscape from erosion. This will also see a decrease in mass movement events.

 

Vegetation is also helpful as plants store water, meaning that less water flows in to rivers.  Drainage basins with more forestry see less intense flooding as plants uptake water to use for photosynthesis.

 

By having more trees, there is the potential for an increase in biological weathering as the roots from trees penetrate in to the rocks and split them apart.

  • Reducing flood risk

  • Habitat creation

  • Carbon sequestration

  • Good for human quality of life as new outdoor spaces are created (e.g. for dog walking or hiking)

  • Managing the basin can be time, resource and money intensive

  • Trees are often planted in monocultures and it takes a long time for ecosystems to revert to being genuinely mixed woodlands

  • Woodlands can be fire risks in the summer

  • Other land uses, such as farming, can be displaced

Urbanisation and floodplain zoning

687,000 live in the river tees catchment area

floodplain zoning is minimize potential damage by designating areas for uses based on their susceptibility for flooding

Urbanised drainage basins mean an increase in impermeable surfaces. If water cannot infiltrate in to the soil then it flows more quickly in to river channels via surface runoff.  This causes 'flashier' floods with more discharge in shorter periods of time. This increases erosion rates and erosion can cause mass movement events (e.g. on the outside bend of meanders)

  • Limited direct positive impacts of urbanisation (although this is sometime the reason other protection is put in place)

  • Floodplain zoning keeps critical urban infrastructure away from commonly flooded areas reducing the impact of floods on society.

  • Urbanisation disrupts natural processes and increases flood risk

  • An increase in urban areas means a decrease in rural (natural) spaces which has impacts on species habitats, diversity, food chains and carbon sequestration

  • Urban areas tend to be darker so they absorb more heat and add to the urban heat island effect