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Historic Water Use andGroundwater Trends in the
Suwannee River Basinfunded by SJRWMD
Kathleen McKee, M.S.Research Coordinator
UF Water Institute
For Santa Fe Springs Working Group Meeting May 19, 2011 in O’Leno State Park Florida
Statistical Evaluation Of Long Term Groundwater Level In Northeastern
Florida And Southern Georgia
• This project involved compilation and statistical trend analyses of historic hydrologic data (groundwater levels, rainfall, streamflow)
• in Suwannee River Basin counties• of Florida and Georgia • from 1980 to 2007
Also analyzed GWin northeast FLcounties
SPRINGSHEDSIchetucknee and Santa Fe springs
Number of Stations
• 132 groundwater levels (SRWMD, SJRWMD, USGS)– Includes NE Florida wells from SJRWMD– ONLY wells in the Floridan aquifer
• 44 rainfall stations (NCDC)
• 22 streamflow stations (USGS)
Data Compilation• Data combined into annual calendar year time series for the
period 1980 to 2007
• Annual average time series were used for groundwater & streamflow– GWL: 20 years of data with at least 2 measures / year– Streamflow: 10 years of daily averages
• Total annual inches time series were used for rainfall• Rain: 20 years of data with at least 8 monthly total / year
• Additional groundwater level data in northeast Florida and southeast Georgia were added (request from SJRWMD).
Statistical Trends• LOWESS – graphical evaluation to determine if
monotonic or piecewise (Cleveland, 1981) • Trend detections (for both monotonic and
piecewise) were conducted using Mann-Kendall test (Hamed, 2008; Hamed and Rao, 1998)
• Confid levels:– > 95%, very certain (there is a trend) (p-value < 0.05)– > 90%, probably trending (p-value < 0.10) – > 80%, possible (p-value < 0.20) – < 80%, no trend detected
MonotonicVery certain downwardSlope = 1.38 ft/yrp-value = 0.014
MonotonicNo Trend Detectedp-value = 0.175 slope = -0.099 ft/yr
Piecewise
1st section: Very certain upwardp-value = 0.014slope = 1.38 ft/yr
2nd sectionNo Trend Detectedp-value = 0.161slope = 0.478 ft/yr
7 USGS - GW level
52 SRWMD – GW level
73 SJRWMD, USGS -Groundwater level
Upward trend
22 NCDC – rainfallNo trends
22 NCDC - rainfall1 trending down Dixie
2 rain stations
NO trendP-value = 0.22
TrendP-value = 0.01
9 USGS – streamflowNo trends
13 USGS – stream flowNo trends
GW Trend Results Significant trends (conf level > 85%):• 12 wells in SRWMD • 5 USGS wells in Georgia• 28 SJRWMD wells
All were downward except one in St. Johns County.
Counties with Signif GW reduction
• Georgia– Worth, Tift, Cook
• Florida (SRWMD)– Baker, Bradford, Lafayette, Union
Water Use data estimation• from 1980 to 2007 in millions of gallons per year.
• Agric from USGS = Agricultural calculated by USGS every 5 years using estimated irrigated crop acreage mul tiplied by a use coefficient from selected crop irrigation models;
• Agric we calculated = estimated crops reported by NASS * recommended irrigation for that crop
• DomSelfSup = Domestic Self-Supply (USGS calculates using statewide per capita water use rate * population not using public supply)¥;
• PubSupp = Public Supply (from monthly permittee reporting); • Comm Ind Pow = Industrial/commercial/mining/power (from
monthly permittee reporting).
7 USGS - GW level
Water Use estimation data
Water Use estimation data
TiftCountyGeorgia
Water Use estimation data
Cook CountyGeorgia
52 SRWMD – GW level
Water Use estimation data
Baker CountyFlorida
Water Use estimation data
BradfordCountyFlorida
Water Use estimation data
LafayetteCounty Florida
Water Use estimation data
UnionCountyFlorida
Water use data
5 year reports done by Rich Marella at USGS:
http://pubs.usgs.gov/sir/2009/5125/
Water Use: important & not easy!Here is what Agriculture estimates look likewhen we try to do them:
Water Use: important & not easy!Here is what Agriculture estimates look likewhen we try to do them:
Thank you!
Kathleen [email protected]
Reports online: http://www.sjrwmd.com/technicalreports/pdfs/SP/SJ2010-SP12.pdf http://www.sjrwmd.com/technicalreports/pdfs/SP/SJ2010-SP11.pdf
