Droughts

The UK drought portal is a tool to help visualise the current meteorological conditions across the UK, and understand the severity and magnitude of drought at different spatial scales across the UK over the past half century. Droughts can be visualised and explored through interactive maps and graphs. Data is updated at the beginning of each month.

Launch the drought tool

The UK drought portal shows the relative magnitude of drought events within river basins and individual catchments based on rainfall deficits over durations ranging from 1 to 24 months. In future this will be extended to include the impact of varying evaporation rates, as well as drought metrics based on river flow and groundwater conditions.

At present, the UK Drought Portal provides an assessment of drought severity based on a single precipitation dataset and one particular indicator (the Standardized Precipitation Index, SPI). As with any hydrological/meteorological dataset, there are important limitations that the user should be aware of. Most importantly, the areal estimates of rainfall are based on a relatively sparse network and may yield different areal averages to results from higher density networks used by regulators/measuring agencies. The SPI is also sensitive to various aspects of its formulation (e.g. choice of statistical distribution, standard period etc; see also Svensson et al. 2017) and results could vary in comparison with other applications of the SPI.

As such, the UK Drought Portal is designed for awareness of the current water resource/dry weather situation, and in this regard it should be considered alongside other datasets and other indicators. As a result of the uncertainty of the rainfall estimates at the 5km scale derived from a relatively sparse underpinning rain gauge network, it is not recommended that the portal be sole source of any operational analysis.

There are many other sources of information for drought monitoring, notably the Hydrological Summaries produced at CEH and the Water Situation Reports produced by the Environment Agency (EA) and similar products developed by Natural Resources Wales (NRW) and the Scottish Environment Protection Agency (SEPA). EA, NRW, SEPA and the water utilities also have regulatory and operational duties to plan, respond and manage dry weather and drought incidents to mitigate their impacts on people and the environment. Users of the Portal should be aware that the Portal is only one measure of drought, based on one indicator (rainfall) and therefore the information on the Portal does not provide a full picture of drought status or impacts, as considered by the regulators and water utilities, who have particular triggers and terminology to indicate drought status.

The drought indicators on the portal have been derived through work on several NERC funded drought projects, DrIVER and Historic Droughts. Through these projects, much analysis has been undertaken to test the utility of drought indicators for indexing drought severity in the UK – for further information see the project websites and references below.

 

The data

The data within the drought portal are based on the Standardised Precipitation Index (SPI) – an indicator of drought that is widely used internationally for drought monitoring. This normalises rainfall deficits based on the historic record, meaning the current situation is expressed relative to the past range of variability for the place in question.

This means the index can be compared between localities with very different rainfall regimes (comparing, say, a wet catchment in upland Scotland with a dry catchment in low-lying East Anglia), and between times of year.

This is particularly important, as droughts occur in all regions, including areas that are generally known for being wet. And droughts are not just events that occur in the summer; rainfall deficiencies in winter are important as they result in less recharge of groundwater and less replenishment of reservoirs. Drought should be defined in relative terms, i.e. as below normal water availability for the time of year, and the place in question. The SPI allows current drought conditions to be expressed in these terms, and so allows comparisons between diverse places, and between different seasons.

The rainfall deficit can be calculated over different time periods, in this case over 1, 3, 6, 12, 18 or 24 months. SPI statistics over shorter durations generally represent shorter, more intense droughts which could impact on, for example, crop growth, while those over longer periods represent whole or multi-year droughts which could affect river flows, reservoir levels or groundwater storage.

Screenshot of the portal

The SPI is calculated initially on a 5km grid, based on rainfall data from the UK Met Office. The 5km rainfall is aggregated up to river basins from CEH’s Integrated Hydrological Units (IHU) dataset, at two different scales to represent the impacts over wider areas; the IHU Hydrometric Areas consist of over 100 UK water management areas, the IHU groups is a dataset of around 400 whole river catchments of around 400km2 across the UK.

Please note SPI data up to 2015 is published and available to download ( see below). Data from 2016 to present is unpublished and provisional and therefore is available for visualisation on the portal but is not yet downloadable.

Launch the drought tool

Screenshot of the portal

 

Access the data/services

The SPI grids, the spatial catchment areas and the derived SPI for these areas are all freely downloadable from the Environmental Information Data Centre (EIDC) for the validated period (up to the end of 2015). In addition, web map services (WMSs) are available to enable the integration of drought maps within other applications, and programmatic access to the data to enable further analysis and integration with other datasets.

The data can be accessed from the following links. They also detail licensing and citation details.

Standardised Precipitation Index 5km grid (1862-2015)
(https://doi.org/10.5285/233090b2-1d14-4eb9-9f9c-3923ea2350ff)

Metadata

licence

 

Integrated Hydrological Unit Areas
(https://doi.org/10.5285/3a4e94fc-4c68-47eb-a217-adee2a6b02b3)

Metadata

licence

WMS

Integrated Hydrological Unit Groups
(https://doi.org/10.5285/f1cd5e33-2633-4304-bbc2-b8d34711d902)

Metadata

licence

WMS

Standardised Precipitation Index time series for Integrated Hydrological Units Hydrometric Areas (1862-2015)
(https://doi.org/10.5285/a754cae2-d6a4-456e-b367-e99891d7920f)

Metadata

licence

 

Standardised Precipitation Index time series for Integrated Hydrological Units Groups (1862-2015)
(https://doi.org/10.5285/10.5285/a01e09b6-4b40-497b-a139-9369858101b3)

Metadata

licence

 

UKCP09: Met Office gridded and regional land surface climate observation datasets

Metadata

 

 

Terms and conditions of use apply to all of the datasets. While the data is freely usable for research purposes and for commercial internal business use, those wishing to build commercial services directly from CEH data are required to contact CEH data licensing.

 

References

Barker, L. J., J. Hannaford, A. Chiverton and C. Svensson (2016). From meteorological to hydrological drought using standardised indicators. Hydrol. Earth Syst. Sci. 20(6): 2483-2505. 10.5194/hess-20-2483-2016

Svensson, Cecilia; Hannaford, Jamie; Prosdocimi, Ilaria. (2017). Statistical distributions for monthly aggregations of precipitation and streamflow in drought indicator applications. Water Resources Research, 53 (2). 999-1018. 10.1002/2016WR019276

 

Other sources of hydrological situation monitoring information:

Hydrological Summaries http://www.hydoutuk.net

Hydrological Outlooks: https://nrfa.ceh.ac.uk/monthly-hydrological-summary-uk/p>

EA Water Situation Reports for England: https://www.gov.uk/government/collections/water-situation-reports-for-england

Water Situation Reports for Wales: https://naturalresources.wales/water/resources/water-situation-report

Please provide feedback on the portal, the datasets available, and the data services provided.


The CEH Droughts Portal is enabled by data from the Met Office
Met Office

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