Background

Background Monitoring Prediction Historical Data

About Drought

Drought is a part of North Carolina's climate - just like floods, hurricanes, and other severe weather. Drought can affect large regions at once, and can last anywhere from weeks to years. The time frame over which drought impacts accumulate and the wide-ranging sectors that can be impacted by a drought make arriving at an all-encompassing definition elusive. That said, several definitions exist that attempt to distinguish between the time frames and sectors that are commonly impacted by drought.

ECONET Station

Meteorological drought is defined as a deficit in the amount of precipitation falling over a given interval of time for a specific location, where the amount of deficit is determined using the normal amount that would be expected over the same interval and for the same location. Because different regions have different weather patterns, normal precipitation can vary drastically from one location to the next. Similarly, normal precipitation for a given interval of time can vary from one season to another. Meteorological drought is not tied to any specific impacts, but as the period over which the precipitation deficit occurs increases, meteorological drought can lead to other forms of drought.

Agricultural water use for irrigation
Image courtesy of AgroClimate

Agricultural drought is generally defined by insufficient moisture to meet the needs for crop production and typically occurs on timescales of a season or less. Frequently, agricultural drought impacts manifest as wilted and withered crops, but if conditions persist, it can lead to reductions in harvest quality and quantity. Agricultural drought impacts typically result from reduced soil moisture, but can be exacerbated by reduced groundwater or reservoir levels, increased evapotranspiration caused by high temperatures combined with decreased precipitation, and even strong winds. Agricultural drought impacts are also dependent on the specific crop and the stage it is at in its life cycle when drought conditions occur. For example, corn is highly susceptible to impacts resulting from insufficient soil moisture, especially when combined with higher temperatures, during its silking stage.

Hydrological drought focuses on impacts to reservoirs, lakes, groundwater, and stream flow that are caused by the accumulated effects of reduced precipitation over long periods of time. Because the time it takes for these effects to become noticeable can range from months to years, hydrological drought often lags behind both meteorological and agricultural drought.

Lake Mead Historic Low- July 11, 2014
Image courtesy of the National Weather Association

Socioeconomic drought refers to the combined effects of human demand for water and reduced water supply due to drought. This form of drought can have far-reaching consequences and demonstrates the fact that the various forms of drought described here are not mutually exclusive. For example, an agricultural drought can lead to reduced crop yield. Additionally, to compensate for reduced moisture from precipitation, growers may use irrigation, leading to a more costly harvest. This can in turn lead to higher grocery-store prices. Longer-term deficits in precipitation can lead to diminishing lake and reservoir levels, causing water quality concerns and reducing recreation activities. Tourism to the area may be reduced as a result of fewer boat slips or access to swimming spots. To compensate, local businesses might reduce their hours or hire fewer workers. The economic impact of the drought can be felt long after the return of more normal conditions.

This last form of drought highlights the importance of impacts: without impacts there is no drought, only dry weather. A drought is therefore measured in terms of its impacts, and often objective indices are formulated as ways to measure drought impacts.

Drought Status

More information on the current status of drought in North Carolina and across the United States can be found on the US Drought Monitor, which is created weekly. Additionally, information about drought impacts can be found on the National Drought Mitigation Center's Drought Impact Reporter. This tool displays reports from the media, the National Weather Service, individual users, cooperative observers, posted water restrictions, and official burn bans. To learn how to get involved, see the Community Collaborative Rain Hail and Snow Network's (CoCoRaHS) drought page.

Monitoring>>