A comprehensive and detailed 669 page review of the current scientific knowledge about drought in the UK has flagged up gaps in current understanding of the causes, impacts and management of drought.

Th major project has reviewed the current scientific knowledge about drought in the UK, including how drought may alter due to climate change, and the implications for both the catchment environment and the management of water resources, both now and in the future.

The report highlights the fact that droughts are complex events and processes that can vary in duration, timing, location, and severity. These differences can cause different impacts on the environment, farming, and water supply. Until now droughts have been infrequent, meaning there is limited data and experience of impacts and responses. This is further complicated by uncertainty in how climate change may affect drought.

The review focused on three themes:

• the physical processes that drive droughts
• the impacts of drought
• the management of drought.

The Environment Agency worked with over 40 experts from 13 different universities, research institutes, and consultancies.

The review draws together and consolidates the current body of knowledge on drought and drought impacts and highlights the extent of our current understanding. It has identified gaps in our knowledge, both topic specific and recurring themes that cut-across drought management and research:

• Changing nature of drought
• Modelling, monitoring and data recovery
• Catchment processes and dynamics
• Development and ending of a drought event
• Drought as a social construct
• Impacts and interactions
• Vulnerability and resilience

According to the review, the large-scale atmospheric drivers of drought remain poorly understood. The nature of UK droughts is expected to change as the climate changes, but there is uncertainty about how, including the magnitude of any changes.

Current research into drought

There have been several recent initiatives in UK drought research, including projects undertaken as part of the Natural Environment Research Council’s (NERC) UK Drought and Water Scarcity research programme, and scientific meetings such as The Royal Society’s “Drought risk in the Anthropocene”. There have also been projects commissioned by the Environment Agency and Defra, and water companies through UK Water Industry Research (UKWIR). The research has often focused on specific questions, and the knowledge created is held across a wide range of different organisations, often in unpublished reports.

Commenting on the implications of drought for future water supply droughts, the report says that projections based on “change factors” (as recommended in current planning guidelines) indicate a likely increased risk to water supply from single-season droughts and decrease to multi-season, because of warmer and wetter winters and hotter and drier summers.

However, the report warns that the change factors approach misses important aspects simulated within climate models, such as the projected lengthening of summer and shortening of winter and increased spatial coherence of drought events. In addition, it points out that there are also large uncertainties around future demand, but household peak demand may increase because of increasing dryness and rising temperatures.

Present and future drought impacts

According to the review, there is currently large uncertainty in the present and future impacts of drought, and significant spatial differences in impacts across different scales. In addition, impact assessments are hampered by uncertainties that are introduced and can grow through the modelling chain, including bias correction and downscaling of climate model outputs. The researchers warn that reconciling secure water supplies and a better water environment will be increasingly difficult in the future.

The review has drawn together and consolidated the current body of knowledge on drought and its impacts and has highlighted where there are gaps in understanding. It also provides a focus for the transfer of existing ideas into practice and an outline for further research to meet scientific and operational needs.

Looking ahead, the Agency wants to build on the findings of the review and identify where further research could deliver benefits for drought management and resilience, both now and in the future.

Click here to download the Chief Scientist's Group summary report

Click here to download the detailed 669 page Review Appendix