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Ann Calver (WMO Commission for Hydrology Advisory Group Member leading on ‘Water, Climate & Risk Management’)
UK Drought Management and Monitoring
WMO/ISDR Expert Group Meeting on Hydrological Drought Indices
Geneva 1-2 September 2011
1
Drought in the UK
Source: UK Climate Change Adaptation Sub-Ccmmittee, 2011; Rodda & Marsh, 2011
uses of abstracted water
rainfall June-Aug 1976
as % of 1971-2000 mean
drought orders issued in England 1976-2008
2
River flow indicators
3Source: Environment Agency
RIVER THAMES AT KINGSTON (NATURAL)Forecasts of mean monthly river flow from July 2006 for 12 months for different % average rainfall
0
5000
10000
15000
20000
25000
30000
35000
Oct-04 Jan-05 Apr-05 Jul-05 Oct-05 Jan-06 Apr-06 Jul-06 Oct-06 Jan-07 Apr-07
Flow
(Ml/d
)
Excep High Note High Above norm Norm Below norm Note low Excep low Actual
120%
% of AverageRainfall
100%80%60%
Projecting river flow indicators
4Source: Environment Agency
Groundwater level indicators
5Source: Environment Agency
Reservoir stock indicators
6Source: Environment Agency
Soil water indicators
7Source: Environment Agency
Drought management plans
EU Environmental Regulator Water Utility
8Source: EU, Environment Agency, Anglian Water
Environmental regulator’s drought management plan
9Source: Environment Agency
Water utility drought manage-ment plan: potential droughtsituation
10Source: Anglian Water
Water utility drought manage-ment plan: during drought conditions
11Source: Anglian Water
Translation of hydrological and other information into determination of an ongoing drought situation
12Source: Environment Agency
European level drought indicator use (1)
hydrological indicator use water scarcity/availability indicator use
Similar EEA information on water scarcity and drought indicators is available relating to meteorological, agricultural, adaptation & mitigation, water abstraction, economic and environmental issues
13Source: European Environment Agency
European level drought indicator use (2)
Examples of existing indicators used by Member States to identify and manage droughts
‘ ... UK, Spain, Portugal, Finland, Italy, Netherlands and France have presented drought indicators ...’
‘ ... there are two main types of indicators, those that are used to prepare for an event and those which make it possible to characterise the event ... ‘
‘ ... all indicators require a complex combination of different parameters and numerous samplings and monitoring systems ...’
‘ .. there is a need for a good and complete indicator system to compare and define droughts ...’
‘ ... parameters included ... may vary from one country to another ... to integrate the specifics of different climatic and geographic conditions ...’
‘ ... it is often not possible to use the single ‘rainfall’ factor to identify and manage a drought ...’
14Source: European Commission
Drought indicators outside the event management period
England & Wales Aridity Index
0.5
1
1.5
2
2.5
3
3.5
1766
1776
1786
1796
1806
1816
1826
1836
1846
1856
1866
1876
1886
1896
1906
1916
1926
1936
1946
1956
1966
1976
1986
1996
1995
1976
19591921 1949
19111933
1893
1870
18681826
20031990long term England & Wales
aridity indexbased on summer (April-September) rainfall and temperature anomalies
River Thames basin hydrological indicators during a long drought 1889-1910periods below long term averages shaded in red
15
Source: Marsh, Cole & Wilby, 2007
Seasonal and longer outlooks (1)
UK Met Office seasonal precipitation outlook
UKCP 09 rainfall scenarios under
anthropogenic climate changes
generated river flows using output from range of climate models
generated river flow changes using a single climate model
16Source: UK Met Office, CEH Wallingford
surface water – increased sensitivityto environmental derogation
groundwater – potential for poorer yields
Seasonal and longer outlooks (2)
mapping of groundwater drought susceptibilityin chalk aquifer (white)red - highest susceptibility; yellow moderate
17Source: British Geological Survey
Some concluding remarks relating to the wider use of hydrological drought indices
• Compelling need for evaluation of a range of drought indices [& drought forecasting methods] for potential use beyond their original destination
• Fitness for purpose is the key concern, together with early availability: ‘standard’ hydrological indicators have advantages but may not override local issues of availability, applicability etc
• Future indices may show greater use of remotely-sensed data and model-generated data, augmenting ‘conventional’ observations
• Indices do not remove the need for sound judgement
further information: anncalver@lwrc.co.uk18
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