Assessing the ecological impact of reservoirs

Our scientists monitor, analyse and quantify flow regimes in rivers and assess the ecological impacts of reservoir operations.

CAPABILITY:

Assessing the ecological impact of reservoirs

Reservoirs may impact river ecosystems in varied ways.

When associated with in-river structures like dams, reservoirs can affect a river’s longitudinal connectivity and fragment its catchment.
The operating rules for storing and releasing water can disrupt a river’s natural hydrological regime and environmental flows.
Releasing reservoir water can modify river water quality and ecology, for instance by altering a river’s thermal regime or enabling the spread of diatoms throughout its network.

At UKCEH, our scientists monitor, analyse and quantify flow regimes in rivers and assess the ecological impacts of reservoir operations. We also develop ecological and hydrological models to help water companies understand how reservoirs modify river regimes and ecosystems, and find solutions.

Image credit: Roger Bradshaw

CASE STUDY:

Modelling changes in river flow regimes

UKCEH scientists modelled the response of macro-invertebrate indices to changes in river flow regimes resulting from planned reservoir schemes in the Fens and South Lincolnshire. This project was led by Mott Macdonald on behalf of Anglian Water.

Different operating scenarios were run through an eco-hydrological model to assess their potential impact on biological indices commonly used as proxies for river ecology.

CASE STUDY:

Reservoir impacts on Thames algal bloom risk

UKCEH is conducting research for Thames Water to investigate the impact of reservoir inputs on the algal community and on algal blooms in the River Thames.

As part of this work, water and associated algae from Farmoor and Wraysbury Reservoirs have been mixed with Thames water and incubated within the AQUA-REP facility at Wallingford. This allows us to assess the growth rates of diatoms, green algae and cyanobacteria resulting from reservoir inputs.

We have also been working with Atkins to monitor the water quality and algal communities of these reservoirs at weekly intervals since March 2020.