The Kentucky Division of Water continuously monitors hydrologic conditions throughout the state, including precipitation, streamflows, lake elevations and various drought indices. This information is used to detect emerging drought conditions, to identify the locations and severity of drought and to provide timely and appropriate public notification.
Statewide Summary of Drought Development
UPDATE Oct. 10, 2008 - GOVERNOR DECLARES STATE OF EMERGENCY FOR MAGOFFIN COUNTY (To view press release, please click here.)
Updated Oct. 23, 2008
Drought conditions remain in place across the state. The next few days do hold the promise of some relief as a system approaches from the west that is anticipated to deliver potentially significant precipitation. In the past week a handful of water suppliers have issued advisories to raise customer awareness about the continuing drought and to ask for voluntary conservation in light of the uncertainty as to when drought conditions may break. The threat level to the vast majority of water supplies across the state is low at this point as we enter a period where temperatures and evapo-transpiration will be decreasing and the probabilities for precipitation should be increasing. It should also be noted that most of the U.S. Army Corps of Engineers projects have started drawdown to winter pool which means an increase in flows of regulated waterways that are home to many of our states public water supplies. The Division of Water will continue to monitor conditions as we move forward.
Useful Drought Indicators
PRECIPITATION
The Division of Water monitors a network of 24 daily climate-reporting stations to track developing shortages of precipitation. For the year, precipitation deficits for Kentucky range from 76 percent of normal in the Eastern climatic division to 106 percent of normal in the Bluegrass division. The annual deficit in southeastern Kentucky, which includes the headwaters of the Kentucky, Licking, Cumberland and Big Sandy river basins, is in the range of 6 to 16 inches. The current 30-day precipitation totals for the Western, Central, Bluegrass and Eastern climatic divisions average 66, 64, 42 and 22 percent of normal, respectively.
STREAMFLOWS
Overall, streamflows continue to show slight improvement. On Sept. 23, 2008, approximately 55 percent of discharge measurements on the United States Geological Survey’s continuous streamflow monitoring network for Kentucky were below normal. Today, approximately 40 percent are at that same level. As we continue to progress through the fall season, expect streamflows to show progressive improvement especially on those rivers being influenced by releases from U.S. Army Corps of Engineers reservoirs through the process of winter drawdown.
The 28-day average streamflow indicates that overall flows have been within a normal range for the Big Sandy, Lower Cumberland, Green, Salt and Tennessee river basins along with the Purchase area. In the Little Sandy, Licking, Kentucky, Upper Cumberland and Tradewater river basins the 28-day average flows are below normal. Seven-day average streamflows are below normal for the entire state with the exception of the Purchase area.
LAKE ELEVATIONS
Most small water supply lakes continue to exhibit normal drawdown. For those that are below normal for this time of year, reports are that they are not as low as they were at this time last year. Most lakes under the control of the Huntington District, Louisville District and Nashville District of the U.S. Army Corps of Engineers have started drawdown to winter pool. Those that haven’t typically begin drawdown in November. Taylorsville Lake in Spencer County is approximately 2 feet below winter pool elevation and doesn’t begin drawdown to winter pool until the end of November. Releases from Corps of Engineers reservoirs are important to the status of many Kentucky rivers as sources of supply for drinking water, assimilation of wastewater discharges, water quality and aquatic habitat. These rivers include the Green, Barren, Rough, Nolin, Kentucky, Salt, Licking and Big Sandy rivers.
DROUGHT INDICES
Assessing the severity of a drought is made easier with the use of drought indices that combine various source information into a single representative value of drought severity. The Palmer Drought Severity Index uses data for precipitation, temperature and evapo-transpiration to calculate a number that can be compared across different times and locations. This index was developed in the 1960s in Kansas and Nebraska but has since become a part of drought monitoring in a majority of the United States. The Palmer Drought Severity Index is updated weekly on Monday afternoons.
The Drought Monitor represents a comprehensive assessment of several factors that contribute to the development of drought or that indicate the severity and potential persistence of drought. The Drought Monitor is updated weekly on Thursday mornings.
Updated Oct. 23, 2008
Palmer Drought Severity Index values have declined slightly in the past week. The Palmer Drought Severity Index issued on Oct. 20, 2008, places the Western and Central climatic divisions in the near-normal category with index values of -1.40 and -1.76, respectively. The Bluegrass Climatic Division remains in moderate drought with an index of -2.33 and the Eastern Climatic Division remains in severe drought with an index value of -3.22.
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0 to -0.99 = near normal
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-1.00 to -1.99 = mild drought
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-2.00 to -2.99 = moderate drought
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-3.00 to -3.99 = severe drought
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-4.00 and below = extreme drought
It is important to note that the Palmer Drought Severity Index is used as a general index of drought over large geographic areas defined by the four climatic divisions of Kentucky. Rainfall that affects one part of a climatic division may substantially improve drought conditions on a county or multi-county level but have little or no impact on the regional average conditions defined by the Palmer Index.
Updated Oct. 23, 2008
An area in southeastern Kentucky is currently designated as in extreme drought by the U.S. Drought Monitor. The boundary of this designation which extends north from Georgia, South Carolina, North Carolina and Tennessee encompasses all or portions of Wayne, Russell, Casey, Adair, Lincoln, Pulaski, Rockcastle, Laurel, McCreary, Whitley, Knox and Bell counties in Kentucky. Surrounding the area of severe drought designation is an area that extends north from Allen County to Edmonson County northeast to Nelson County and east to Lawrence County. Above this area is a band characterizing conditions as moderate drought. The western boundary of this area runs north east from Graves County to Hancock County. The area west of this line is considered as being abnormally dry to normal in the north west corner of the Purchase area.
As a drought indicator, the Drought Monitor is not limited to four large climatic divisions, rather it incorporates the Palmer Index as just one of several indicators of drought development in a given area. These other indicators include more short-term components including the Crop Moisture Index, Standardized Precipitation Index and weekly streamflow percentiles. The Palmer Drought Severity Index and the Drought Monitor should be considered in combination with more localized data such as rainfall, streamflows, groundwater levels and climatic outlooks to form an accurate assessment of drought severity in a given location.
OTHER LINKS OF INTEREST:
- The Federal Emergency Management Agency (FEMA) provides additional water conservation tips to help you conserve water at home.
- Additional sources of weather-related information include the Kentucky Climate Center at the Department of Geography and Geology at Western Kentucky University.
- The Drought Severity Map is available from the Climate Prediction Center of the National Oceanic and Atmospheric Administration and presents drought conditions for the entire United States on one page.
- The Department of Biosystems and Agricultural Engineering of the College of Agriculture at the University of Kentucky also contains Kentucky weather information, including maps indicating amount of rainfall, temperature and moisture index.
- The United States Geological Survey (USGS) maintains a gauging station database that provides streamflow gauging data for the major river basins in Kentucky.