World Meteorological OrganizationWorking together in weather, climate and water

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Hydrological Drought Indices: Outcomes of Previous

WorkshopsRobert Stefanski

Chief,Agricultural Meteorology Division

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Overview of

WMO

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WMO OMMWorld Meteorological Organization

• United Nations agency for weather, climate, hydrology and water resources and related environmental issues.

• 189 Members from National Meteorological and Hydrological Services (NMHS)

• 10 major scientific & technical programmes (Secretariat)• 8 Technical Commissions advise & guide activities of

programmes (Experts)• 6 Regional Associations involved in implementation

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Five priority Areas

• Global Framework for Climate Services;• Aviation meteorological services;• Capacity-building for the developing and least

developed countries;• Implementation of the WMO Integrated Global

Observing System (WIGOS) and WMO Information System (WIS);

• Disaster risk reduction

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WMO OMMWMO Technical Commissions

• Commission for Aeronautical Meteorology (CAeM)• Commission for Agricultural Meteorology (CAgM)• Commission for Atmospheric Sciences (CAS)• Commission for Basic Systems (CBS)• Commission for Climatology (CCl) • Commission for Hydrology (CHy)• Commission for Instruments and Methods of Observation (CIMO)• Joint WMO-IOC Commission for Oceanography and Marine

Meteorology (JCOMM)

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Drought

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The Cycle of Disaster ManagementThe Cycle of Disaster Management

Source: Wilhite - NDMC

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Comparing drought to other natural hazards–

• slow onset, “creeping phenomenon”, a non-event

• difficult to determine drought onset and end• absence of a precise, universal definition• impacts are nonstructural and spread over

large areas• severity and impacts best defined by multiple

indices and indicators

Source: Wilhite - NDMC

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• no consistent methodology for assessing impacts or a data base for archiving impacts

• impacts are complex, affect many people, and vary on spatial and temporal timescales, multiple and migrating epicenters

• mitigation interventions are less obvious• water shortages increase conflict—regulatory, legal

authority (interstate and transboundary issues)• makes monitoring, early warning, impact

assessment, response, mitigation, and planning difficult!

Comparing drought to other natural hazards–

Source: Wilhite - NDMC

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• Causal factors• Multiple

– Regional in scale– Forcing functions not well understood

• Impacts• Institutional structure for monitoring, mitigation,

response, and planning/policy• Societal coping capacity (vulnerability/resilience)• Government policies (e.g., data sharing across

ministries, response measures)• Government/donor response capability

Drought is a normal part of climate in most climate regimes but differs in terms of

Source: Wilhite - NDMC

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Is drought a departure from normal climate

or a part of normal climate?

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Drought is a normal part of climate!

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Spatial Extent

Droughts differ in terms of:

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Natural and Social Dimensions of Drought

RainfallDeficienciesHeat Stress

Meteorological

SoilsCropsRange

LivestockForests

AgriculturalWater SupplySnow DepthRecreation

TourismHydropower

Hydrological

Socio-economic

Decreasing emphasis on the natural event (precipitation deficiencies)

Increasing complexity of impacts and conflicts

Time/Duration of the event

Societal Impact

Increasing emphasis on water/natural resource management

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Components of a Drought Early Warning System

• Monitoring networks– Who is the responsible authority?– Multiple networks?

• Data retrieval systems• Data quality control• Data analysis—converting data into information• Interaction with end users/stakeholders

– Creating an end-to-end-to end system• Information delivery—timely, reliable

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Key Indicators for Monitoring Drought

• climate data (precipitation, temperature)• soil moisture• stream flow• ground water• reservoir and lake levels• snow pack• short, medium, and long range forecasts• vegetation health/stress and fire danger• sectoral impacts

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• Droughts have different physical characteristics

• Society is dynamic so each drought event is superimposed onto society—impacts reflect changing vulnerabilities

• Does your country have a monitoring system for recording drought impacts?

• How do you incorporate impacts into a drought early warning system?

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WMO OMMDrought Indices

• Percent of Normal• Deciles• Palmer Drought Severity Index (PDSI)• Surface Water Supply Index (SWSI)• Standardized Precipitation Index (SPI)• Keetch-Byram Drought Index (KBDI)• Vegetation Condition Index (VCI)• And many more ……

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Previous Workshops

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Lincoln Workshop

• Inter-Regional Workshop on Indices and Early Warning Systems for Drought held in Lincoln, Nebraska, USA from 8 to 11 December 2009

• Co-Sponsors:– National Drought Mitigation Center (NDMC) – United States Department of Agriculture (USDA) – United States National Oceanic and Atmospheric Administration

(NOAA) – United Nations Convention to Combat Desertification (UNCCD) – University of Nebraska-Lincoln, School of Natural Resources – World Meteorological Organization

http://www.wmo.int/pages/prog/wcp/agm/meetings/wies09/index_en.html

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Workshop Objectives

• To review and assess drought indices currently used around the world for the three types of drought (meteorological, agricultural, and hydrological);

• To review and assess the strengths, weaknesses and limitationsof existing drought indices and early warning systems;

• To develop a consensus standard index for each of the three types of drought;

• To develop guidelines for WMO Members in implementing and improving drought early warning systems.

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Workshop Sessions• Drought Indices and Early Warning Systems for Drought: An

Overview

• Drought Indices in Current Use: Regional Perspectives (Africa, Asia, South America, North and Central America, South-West Pacific, and Europe)

• Impacts of Drought

• Hydrological and Agricultural Droughts

• Drought Monitoring: Current and Emerging Technologies

• Breakout Sessions to Develop Consensus Standard Indices for Different Types of Droughts

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Breakout Groups• Mostly followed methodology from Keyantash and Dracup (2002)

“The Quanification of Drought: An Evalution of Drought Indices”– Bulletin of AMS - August 2002

Used following criteria:• Robustness• Tractability• Transparency• Sophistication• Extendability• Dimensionality

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Meteorological Drought Group

• Precipitation Percentiles (includes deciles and quartiles)

• Percent of Normal Precipitation

• Palmer Drought Severity Index (PDSI)

• Standardized Precipitation Index (SPI)

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Indices Robust Tract Trans Soph. Extend. Dim. SumSPI 4.56 4.44 4.22 3.11 4.80 4.22 25.36

Percentile Ranking 4.25 3.89 4.00 3.25 4.38 4.33 24.10

PDSI 2.57 2.33 2.38 3.33 3.14 2.50 16.26

Percent of Normal 3.22 4.38 4.44 3.22 3.25 3.78 22.29

Meteorological Drought

Note: Percentile rankings include deciles and quartiles.

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Meteorological Drought Outcome

• Standardized Precipitation Index (SPI) and Percentiles were very close, but the SPI had a slightly higher score

• Percent of Normal Precipitation was ranked third

• PDSI was a distant fourth

Recommendation: Use drought indices that are based on a sound statistical and historical perspective (SPI and Percentiles). The SPI is the recommended Meteorological drought index.

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Agricultural Drought Outcome

• No consensus (17 indices)

Conclusions • Water Balance models are quite good since they take into account soil and crop growth

• NDVI is very useful and is comparable with hydrological balance

• For all indices, a temperature component is important

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• Not well understood ~ complex• Lags meteorological indices• Basin specific• Managed systems and unmanaged systems and

interconnections (eg. northern Rocky Mountains and the Missouri river)

• Complicated by water scarcity (competition for resources on average years)

• Major changes in land use (or wild fires) can corrupt time series data

• Data hungry and not easy to calculate

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WMO OMMIndices considered

• Reservoir Levels (unique to location/system and apatite for restrictions)

• Composite Hydro Index• Low flow index (e.g. 7 day moving average

inflow)• % NRR type (departure from the mean)• SPI as a ‘surrogate’ in areas with sparse data

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WMO OMMHydrology Summary Table

INDEX Robust. Tract. Trans. Sophis. Extend. Dimen. SUM

Reservoir Level (managed) 3.13 3.67 5.0 1.57 2.75 5.0 21.11

Percent Normal Rainfall 2.88 5.0 3.83 1.89 4.88 3.57 22.04

SPI 3.5 4.0 2.83 3.10 4.33 3.13 20.89

Composite Hydro Index 4.0 2.0 2.67 3.44 3.22 2.11 17.44

Low Flow Index 3.4 2.75 3.11 3.10 2.88 3.125 18.36

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Hydrological Drought Outcome

• No consensus (6 indices)Recommendations• Examine composite indices that take into account streamflow, precipitation, reservoir levels, snowpack, groundwater levels such as:

• Surface Water Supply Index (SWSI)• Aggregate Dryness Index (ADI)• Normalised ADI (NADI) (Barua and Perera 2009)

Also suggested;• Streamflow drought Index (SDI) Nalbantis and Tsakiris (2009)• Artificial Neural Networks (Perera et al. 2009)

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Lincoln Declaration - Recommendations

• The National Meteorological and Hydrological Services (NMHSs) around the world are encouraged to use the SPI to characterize meteorological droughts and provide this information on their websites, in addition to the indices currently in use.

• A comprehensive user manual for the SPI should be developed that will provide a description of the index, the computation methods, specific examples of where it is currently being used, the strengths and limitations, mapping capabilities, and how it can be used.

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Lincoln Declaration - Recommendations

• Two working groups with representatives from different regions and observers from UN Agencies and Research Institutions (and water resource management agencies for hydrological droughts) be established to further discuss and recommend, by the end of 2010, the most comprehensive indices to characterize agricultural and hydrological droughts.

• Recognizing the need to develop a framework for an integrated approach for drought monitoring to address all sectoral needs, a comprehensive study of consensus drought indicators is needed for potential global application.

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Lincoln Declaration - Recommendations

• A simple, systematic analysis of drought impacts in different sectors should be initiated in all affected countries in order to provide useful decision-making information for policy-makers.

• Drought indices and early warning systems must be implemented from the beginning with the end-users in mind. To accomplish this goal, a multi-disciplinary approach incorporating user involvement is absolutely necessary.

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Recommendations from Murcia

• Given enhanced availability and access to data, tools, and guidance materials, meeting recommends that countries move beyond the use of just rainfall data in computation of indices for the description of agricultural droughts and their impacts.

• It is important to use more comprehensive data on rainfall, temperature, and soils in computing drought indices. Hence, greater cooperation is required between different ministries and agencies responsible for addressing drought issues at the sub-national, national, and regional levels.

• Recognizing that diverse data and information are required for the use of a composite approach (such as the U.S. Drought Monitor), the meeting recommends that all countries examine this option.

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Current Actions

• The recommendation to use the SPI was approved by the WMO Executive Council in June 2010 and by WMO Congress in 2011.

• The UN International Strategy for Disaster Risk Reduction (ISDR) is providing funding for the meetings of the working groups on agricultural (June 2010 - Spain) and hydrological (Sep 2011 - Geneva) drought indices.

• With these recommendations, WMO contributed to ISDR on chapter on drought risks for the 2011 UN Global Assessment Report on Disaster Risk Reduction.

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WMO OMMOther Initiatives

• Integrated Drought Management Programme

• High-Level Meeting on National Drought Policies

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Proposed Integrated Drought Management Programme

• WMO and the Global Water Partnership are proposing an Integrated Drought Management Programme. Similar to APFM

• Targeting intergovernmental, governmental and non-governmental organizations involved in drought monitoring, prediction, drought risk reduction and management.

• Primary beneficiaries are expected to be governmental institutions, agencies responsible for developing drought management policies and/or implementing systems for drought monitoring, prediction, preparedness and mitigation.

• The principal approach to develop global co-ordination of efforts to strengthen drought monitoring, risk identification, drought prediction and early warning services and development of drought management knowledge base.

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Proposed Integrated Drought Management Programme (cont)

• The expected services to be provided are:– Regional coordination of drought monitoring, prediction and

early warning activities– Inception of pilot projects and coordination of regional projects

to showcase best practices – Collection and dissemination of information and knowledge on

good practices; – Guidelines, methodologies, tools and supporting documentation

on policy development and management practices and procedures; and

– Capacity building and advice on Integrated Drought Management.

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WMO OMMGoals of National Drought Policy (1)Goals of National Drought Policy (1)

• Proactive mitigation and planning measures, risk management, public outreach and resource stewardship as key elements of effective national drought policy.

• Greater collaboration to enhance the national/regional/global observation network and information delivery system to improve public understanding of and preparedness for drought.

• Incorporation of comprehensive governmental and private insurance and financial strategies into drought preparedness plans.

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WMO OMMGoals of National Drought Policy (2)Goals of National Drought Policy (2)

• Recognition of a safety net of emergency relief based on sound stewardship of natural resources and self-help at diverse governance levels.

• Coordination of drought programs and response in an effective, efficient and customer-oriented manner.

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WMO OMMWhy a HMNDP is needed ?Why a HMNDP is needed ?

• Despite the repeated occurrences of droughts throughout human history and the large impacts on different socio-economic sectors, no concerted efforts have ever been made to initiate a dialogue on the formulation and adoption of national drought policies.

• Amongst all the countries in the world, only Australia has a national drought policy which provides a clear description of when and how communities affected by droughts could seek drought relief under a legal framework.

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WMO OMMWhy a HMNDP is needed ? (2)Why a HMNDP is needed ? (2)

• HMNDP could ensure that government actions transcend far beyond the conventional reactive approaches. In fact, it has been demonstrated traditional drought assistance or relief programs actually result in less self-reliance and more dependence on governments, increasing the vulnerability of sectors to future drought events.

• If more acceptable results are to be achieved while dealing withdroughts, a new approach should be taken and new attitude adopted in dealing with droughts.

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WMO OMMWhy a HMNDP is needed ? (3)Why a HMNDP is needed ? (3)

• A high level meeting could help develop such a new approach through – developing a common understanding of the issues involved, – discussing the different approaches that could be

incorporated into a national drought policy and – finally establishing a framework of a national drought policy

that could help all the nations around the world.

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Suggested Steps for Organization Suggested Steps for Organization of HMNDPof HMNDP

• Seek the approval of the WMO Congress for this proposal (May 2011).

• Develop a comprehensive concept note on national drought policy through an Expert Meeting (July 2011) followed by meeting of the HMNDP International Organizing Committee (HIOC) (2011/2012).

• Organize a Symposium on Integrated Drought Information System (SIDIS) and refine the concept note further (Nov 2011).

• Engage diplomatic missions in Geneva to seek their comments on the concept note (Dec 2011); get comments from capitals (Feb 2012); revise the concept note and organize first meeting with missions (Feb 2012).

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Suggested Steps for Organization Suggested Steps for Organization of HMNDP (2)of HMNDP (2)

• Organize second meeting of HIOC to discuss and finalize programme for HMNDP (March 2012)

• Organize second meeting with missions (May 2012), get their final endorsement of the revised concept note and programme for HMNDP.

• Organize the HMNDPI ( Nov-Dec 2012).

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Thank Yourstefanski@wmo.intwww.wmo.int/agm