IMPETUS: IMproving PrEdictions of Drought To inform USer decisions

Droughts have severe impacts on societies, economies, agriculture and ecosystems. The 1975-76 UK drought had a devastating effect on the UK economy causing an estimated £3,500M loss to agriculture, £700M of subsidence damage to buildings and a £400M cost to the water industry (present day figures adjusted for inflation). Forward planning is critical for managing the impacts of drought, since early action enables stakeholders, such as public water supply and agricultural companies, to curb demand and to effectively manage diminishing water resources. Improved forecasts on drought management (monthly to seasonal) and planning timescales (seasonal to decadal) would be exceptionally valuable for effective drought management and for minimising the negative impacts of droughts.

Droughts are complex events, with impacts dependent on meteorological, hydrological and land surface factors as well as on water demand and management. Consequently, drought forecasting has many components: forecasting meteorological drought (deficit of rainfall), agricultural drought (soil moisture deficit) and hydrological drought (decline in surface water and groundwater), forecasting the consequences of drought for water availability and forecasting the effects of drought management. All of these are uncertain and any improvement in decision-making needs to consider all aspects of the forecast process. IMPETUS focuses on meteorological and hydrological forecasting linked to innovative methods for forecasting local domestic water demand during drought.

IMPETUS is an interdisciplinary proposal that brings together scientists from the meteorological, land surface, surface water and groundwater communities and social scientists from the water demand and forecast usability communities. The project involves internationally-leading scientists and social scientist from three NERC Research Centres (NCAS, BGS and CEH), four leading universities (Oxford, Reading, Newcastle, and Southampton), the Met Office and ECMWF. IMPETUS aims to improve the forecasting of UK drought on monthly to decadal timescales, which will lead to the development of improved decision-making processes. This will be achieved by improving meteorological, hydrological and water demand forecasts and how they are combined to produce drought forecasts. This will be done in conjunction with stakeholders to ensure that drought forecasts are relevant for decision making. IMPETUS addresses WP2 (Forecasting Drought) of the UK Droughts and Water Scarcity call.

We envisage IMPETUS producing a range of high-impact publications in meteorology, hydrology, hydro-meteorological forecasting, water demand modelling and the usability of drought forecasts. The outcomes from IMPETUS will also benefit a wide range of stakeholders. These include informing the Environment Agency (EA) on the ability of the hydrological models used by EA for water resource management to represent drought, and furthering the understanding that underpins key operational projects, including the Hydrological Outlooks project. IMPETUS outcomes will also benefit the Met Office and ECMWF through an improved understanding of the drivers of meteorological drought and recommendations for improving the representation of drought in operational meteorological forecast systems and climate models.

Finally, IMPETUS aims to improve the forecasting of drought on monthly to decadal timescales, which will enable stakeholders to better curb demand and more effectively manage diminishing water resources. In particular, IMPETUS aims to engage stakeholders and assess their needs for drought forecast information, co-producing drought metrics from forecasts to ensure that they support real-world decision-making. Particular examples of this have already been identified through initial discussions with stakeholders including precipitation forecasts for Thames Water and soil moisture forecasts for the agricultural sector.

The overarching aim of IMPETUS is to improve the forecasting of UK drought on monthly to decadal timescales, which will lead to the development of improved decision-making processes. Given the substantial socioeconomic impacts of drought in the UK, there is a broad range of non-academic stakeholders who will be benefit from the outcomes of IMPETUS:

1. The Met Office and ECMWF: IMPETUS outcomes will benefit the UK operational meteorological forecasting centres (i.e. the Met Office and ECMWF) by: i) the improved understanding of the drivers of meteorological drought and their representation in climate models and operational meteorological seasonal and decadal forecasting systems, ii) an evaluation of operational forecasting systems for drought, iii) recommendations for improved forecasts systems and climate models (e.g. recommendations for the resolution of climate models) and iv) an improved understanding of how to produce hydro-meteorological forecasts for UK drought.

2. The Environment Agency: Part of the EA's role is to protect the environment by minimising the impact of droughts while ensure adequate public water supply. IMPETUS will benefit the EA by: i) providing insight into how to improve communication and facilitate the uptake of drought forecasts, ii) addressing the degree of model complexity appropriate to the forecasting of drought evolution across different timescales, iii) providing new methods to combine hydro-meteorological information in drought forecast systems and iv) providing guidance on how to integrate uncertain drought forecasts into decision-making process.

3. End-users of drought forecasts: Many economic sectors are sensitive to the impacts of UK drought including public water supply, agricultural, retail, finance and health. IMPETUS aims to improve the forecasting of drought on monthly to decadal timescales, which will enable stakeholders to better curb demand and more effectively manage diminishing water resources. In particular, IMPETUS aims to engage stakeholders and assess their needs for drought forecast information, co-producing drought metrics from forecasts to ensure that they support real-world decision-making. Initial discussions with stakeholders have already led to decision-relevant metrics being identified (e.g. one month and 3-month ahead precipitation over the Southeast England for Thames Water; one-month and 3-month ahead soil moisture deficit for drought planning in the agriculture sector).

4. Government departments (DEFRA, DECC): Policy-makers and government departments (in particular, DECC and DEFRA) are keen to reduce the negative socioeconomic impacts of drought, which may be possible if mitigation measures are enacted with enough warning. IMPETUS will benefit policy-makers by providing improved evidence-based guidance on the current capability to forecast UK drought.

5. Wider public interest: UK drought is an issue of intense interest to the wider general public (e.g. public discussion of the dry UK winter and spring in 2012; recurring public discussion about the 1975-76 UK drought). Through public engagement (via the project website, a Royal Society exhibition, public engagement material and media engagement - see impacts plans for more details) we will improve public understanding of the drivers of drought and our current capability to forecast UK drought.