IndicatoRs to Impacts for drought Surveillance and management (IRIS)

Droughts are complex, slow-evolving and costly natural hazards. Detecting their onset and tracking their development can be hard, as they spread through the water cycle. Although the UK is stereotypically a wet country, recent droughts in 2012 and 2018 had significant impacts on water supplies, agriculture and the environment. Projected changes to future climate suggests that they will become more frequent and severe in the coming decades. We therefore need to urgently be more resilient to and better prepared for droughts, both now and in a rapidly warming world.

Drought Monitoring and Early Warning (MEW) is an important part of effective drought management, but this is complicated by the challenges in defining drought, the difficulties in identifying drought impacts before they are very severe, and the diverse needs of the wide range of decision makers that use drought MEW information. In the UK, drought research has advanced substantially over the past decade thanks to the £12.5m NERC Drought and Water Scarcity Programme (DWSP) led by the UK Centre for Ecology & Hydrology (UKCEH), as well as other allied international research projects in which UKCEH was heavily involved. This has led to significant progress in the understanding of droughts and the development of drought MEW tools. This includes the UK Water Resources Portal, which provides real-time hydro-meteorological data and drought indicators. However, drought monitoring tools like this typically lack information on drought impacts - despite the fact that this is the single most important piece of evidence required by decision makers to take actions, as has been highlighted in work we have done with key stakeholders from sectors including water supply, agriculture, health, energy and the environment.

Understanding the link between drought indicators commonly used in MEW systems (i.e. that describe the physical drought hazard, e.g. in terms of rainfall or river flows) with the drought impacts seen on the ground has been the focus of drought scientists for some time. However, due to the challenges of collecting and recording drought impacts, the analysis has generally been carried out at large spatial scales (e.g. for Wales as a whole), which are not relevant to decision makers who tend to manage water at more local scales, from field to catchment scale.

In the IRIS project, we propose to address this issue of spatial scale by using new high resolution drought indicators and drought impact datasets to predict drought impacts at a high spatial resolution. We will do this across three integrated Work Packages (WPs): WP1 will focus on gathering data from multiple sources of both drought indicators and drought impacts, including new crop yield data at an unprecedentedly high resolution for the UK. We will also use high resolution remote sensing data which have become available in recent years such as Sentinel-2 to derive proxies for drought impacts (e.g., vegetation indices and wildfires). WP2 will then use the data gathered in WP1 to identify the relationships between drought indicators and drought impacts, and build 'impact functions' that describe these relationships quantitatively, using statistical and machine learning approaches. These relationships can then be used to forecast potential drought impacts using indicators that are readily available in near-real-time. In WP3 we will work with key stakeholders to develop case studies and assess whether the impact forecasts have sufficient skill to be used to manage droughts and mitigate impacts. The findings and outcomes of this project have the potential to be scaled up into a nation-wide drought impact forecasting system through future funding opportunities. An impact-based drought forecasting capability would revolutionise the way droughts are managed and mitigated in the UK, and would have huge potential for transferring to other countries and environments.