8/12/2019 Sheet 1 - What is Drought

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Drought Fact Sheet #1

Defining Drought Is Key When Developing a Drought PlanDefining Drought Is Key When Developing a Drought PlanDefining Drought Is Key When Developing a Drought Plan

What Is a Drought and HowWillIt Affect My Community?

been calculated monthly since 1895 and theresulting data can be found at www.cpc.ncep.noaa.

gov/products/monitoring_and_data/drought.shtml

4. The Crop Moisture Index is derived from thePalmer index and reflects short-term moisturesupply. This index does not work well forlong-term drought studies.

5. The Surface Water Supply Index was designedto complement the Palmer Method in the State ofColorado. The index uses snow pack, stream flow,precipitation and reservoir storage to makeassessments that are unique to each river basin.

6. The Reclamation Drought Index is alsocomputed at the river basin level and addstemperature to the list of parameters used in the

What Is a Drought?There are many definitions of drought. Webstersdictionary defines it as 1:a period of drynessespecially when prolonged that causes extensivedamage to crops or prevents their successfulgrowth; or 2:a prolonged or chronic shortage orlack of something expected or desired.

We also have conceptual definitions of drought,which are stated in general terms that most citizenscan understand readily, such as We are not gettingenough rain, and its starting to affect the land.

There are also operational definitions of drought.These definitions are usually triggered by one of theindexes developed for predicting or describing adrought and can describe the ongoing status of thedrought. Six indexes have been developed in theUnited States to help define when observed

conditions rise to the level of a drought:

1.The Percent of Normal method is one youfrequently hear about during television weatherforecasts. It is easy to compute and understand andquite appropriate for a given location or season.This index is sometimes misunderstood because itis based on a mathematical definition of normal,which often does not correspond with the publicsview of weather.

2. The Standard Precipitation Index is used by

many drought planners. This index can becomputed for different time scales and can provideearly warning of drought conditions. Since thisassessment is based on preliminary data, the valuescan change and lead to significant inaccuracies.

3. The Palmer Drought Severity Index is a widelyused index for drought prediction. It is based onsoil moisture and is used by many federal agenciesto trigger drought relief programs. The index has

This lake near San Luis Obispo, California barely containsany water following a several year long drought.

PhotocourtesyofTimM

cCabe/USDANRCS

8/12/2019 Sheet 1 - What is Drought

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All programs and services of the NARC&DC are offered on a non-discriminatory basis, without regard to race,color, national origin, religion, sex, sexual orientation, age, marital or family status, disability, or political beliefs.

March, 2006

assessment. Both the Bureau of Reclamation and theState of Oklahoma use this index as part of theirdrought planning.

In some cases drought is identified in accordancewith a field of study or interest. For example, there

are specific definitions from a meteorological(rainfall), hydrological (surface and groundwater),agricultural (soil moisture/crop), and socioeconomic(economic effects on the community) perspective.Additional detail is available atwww.drought.unl.edu/whatis/concept.htm

You do not need to understand the details of thedrought indexing systems to make a Drought Plan.But at some point you will need to define thethreshold for putting your plan into action. This iswhat Drought Planning is all about. While

variations in rainfall are normal, they can causesignificant stress on a region that is experiencing aprolonged period of decreased precipitation. Acommunity can prepare for variations and have aclear plan in place for dealing with the effects.

What Affects Can Drought Have on My Community?The possible impacts from a drought depend onwhere you live and what you do. Somecommunities have an economy that is based onagriculture; other communities have an economybased on industry. Some communities rely on

rainfall while others have widespread irrigation andwill be more resistant to short term drought events.Some municipal users rely on surface water, whileothers use groundwater and may not be as likely toexperience water rationing. There are exceptions toall generalizations. Nonetheless, it is important tounderstand that there are common effects that needto be considered in the process of developing aDrought Plan. For more information, see Fact Sheet# 11.

Common Impacts to Municipalities

Drought events have the potential to causesignificant disruption to the lives of urban water

users, who consume an estimated 5 - 7% of thewater resources in the United States. Even thoughthis seems like a very small percentage of the totalwater budget, it is tremendously important from ahealth and political standpoint. Rationing of waterusually starts by voluntary limitations on lawn

watering, car washing and other discretionarywater uses. As supplies grow more limited, theserestrictions can become mandatory. Cities may berequired to change to back-up or alternate watersources at a significant increase in cost. For moreinformation, see Fact Sheet #6.

Common Impacts to IndustryIndustry is credited with consuming 20 - 22% ofthe United States water resources. This wateruse is directly related to jobs and payrolls. Therequirement to curtail or shut down industrial

production due to water limitations can havedevastating effects on a community. In the shortterm this can result in a loss of payrolls as thewater limited plant struggles to maintain itscompetitive position. In the longer term it maymean the loss of the industry due to uncertaintyover the reliability of the water supply. For moreinformation, see Fact Sheet # 4.

Common Impacts to AgricultureAgriculture is attributed to using 65 - 75% of theavailable water resources. Impacts on agriculture

differ significantly based on the availability ofgroundwater and the agricultural communitysreliance on natural rainfall. Reduced yieldscommonly reduce payrolls and cause reducedsales levels for the many companies that servicethe farm industry. Drought Plans can help sustainagricultural business units and their supportingbusinesses by ensuring equitable water distribution.For more information, see Fact Sheet #5.

The NARC&DC would like to thank the USDAsNatural Resources Conservation Service for their

assistance in the development of this fact sheet.