Research and analysis

Scoping a flexible framework for producing river water temperature projections: summary

Published 22 October 2021

Applies to England

1. Chief Scientist’s Group research report summary

This project reviewed alternative approaches to modelling future river water temperature for England. The findings will help the Environment Agency to develop temperature projections and inform measures to help adapt to a changing climate.

2. Background

Climate change is expected to change freshwater ecosystems and water quality. Understanding how and where changes may take place and their likely magnitude will help to project water quality changes and target management activity.

Patterns of change in water temperature may not be the same as for projected air temperature change, for which information is readily available. This study aimed to understand the best approaches for the Environment Agency to use to model future river water temperature projections for England to better inform future management actions.

3. Approach

The project reviewed available approaches for modelling river temperature and grouped them into 4 categories: statistical, process-based, machine learning and hybrid.

The review included consideration of the data and modelling requirements, and the benefits and limitations of each approach to produce projections of river water temperature for England under climate change scenarios. The most suitable methodology for developing these projections given current data availability was identified.

4. Results

Several promising approaches were identified that may be suitable for modelling English river temperatures. ‘Spatial network models’ (a statistical approach) represent the current best approach with machine learning/artificial intelligence techniques holding promise for future development. Data, application purpose and scale all constrain potential applicability of the different approaches.

Decision trees were developed for selecting water temperature models based on methodological approach and data availability over space and time. A potential modelling approach, mixed effect regression, was identified for making English water temperature projections based on constraints in data availability and the scale required for the estimates.

Additional steps needed to develop a water temperature projection for the entire river network were also considered.

5. Conclusions

The ability to generate water temperature projections for England under climate change scenarios is limited by the available data. However, a flexible modelling approach was identified for making projections in some places, which can be extended as more data becomes available.

The study gives the Environment Agency an approach to produce an important source of climate impacts data allowing us to now understand, and prepare for, climate impacts on water quality and river ecosystems.

6. Project details

This summary relates to information from project SC200008, reported in detail in the following output:

• Report: SC200008/R
• Title: Scoping a flexible framework for producing river water temperature projections
• Project manager: Judy England, Chief Scientist’s Group

This project was delivered by the Environment Agency’s Research, Analysis and Evaluation group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

Enquiries: research@environment-agency.gov.uk

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