historic water use and groundwater trends in the suwannee river basin funded by sjrwmd

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 McKeekatmckee@ufl.edu

Reports online: http://www.sjrwmd.com/technicalreports/pdfs/SP/SJ2010-SP12.pdf http://www.sjrwmd.com/technicalreports/pdfs/SP/SJ2010-SP11.pdf