Importance of a Sound Regional Groundwater Flow Model for Water Resource Management

Transcription

1 Imprtance f a Sund Reginal Grundwater Flw Mdel fr Water Resurce Management Wakulla & Len Cunty Sil and Water Cnservatin Districts Natural Resurces Cnservatin Service January 16, 2014 Tdd Kincaid, Ph.D. GeHydrs, LLC 1

2 Prblem Diminishing Grundwater Flw Diminished Spring Flws Reduced flw t Wakulla & Spring Creek springs Spring Creek is nw reversing flw in summers Flw is diverted t Wakulla Diminished water clarity at Wakulla Salt water intrusin at Spring Creek Rapid and pervasive salt water intrusin Spring Creek reversals send salt water at least 3 miles inland via cnduits Salt water persists at depth until grundwater levels rise sufficiently t frce it back ut Duratin f salt water intrusins and vertical extent likely increasing Failing t recgnize and address prblems Pumping and sea level rise imprtant factrs Existing mdels and mdeling appraches incapable f delivering reliable predictins Cedar Key 2

3 Prblem Diminishing Grundwater Flw Diminished Spring Flws Reduced flw t Wakulla & Spring Creek springs Spring Creek is nw reversing flw in summers Flw is diverted t Wakulla Diminished water clarity at Wakulla Salt water intrusin at Spring Creek Rapid and pervasive salt water intrusin Spring Creek reversals send salt water at least 3 miles inland via cnduits Salt water persists at depth until grundwater levels rise sufficiently t frce it back ut Duratin f salt water intrusins and vertical extent likely increasing Failing t recgnize and address prblems Pumping and sea level rise imprtant factrs Existing mdels and mdeling appraches incapable f delivering reliable predictins Cedar Key 3

4 Why are mdels failing? Inaccurate cnceptualizatin Assume Equivalent Prus Media Aquifer is a sand bx Reality Aquifer is karst where cnduit flw is dminant Inaccurate water budget Let mdels dictate hw much water flws thrugh the aquifer Castal bundaries are nt cnstrained Assume large diffuse flw t Gulf f Mexic (n data) Reality Spring flws represent majrity f flw t Gulf f Mexic D nt incrprate all f the key factrs affecting flw Nt large enugh (plitical vs. natural bundaries) Overly simplified spatial and magnitude assignments (i.e. pumping) Lack f data (can usually be vercme with enugh wrk) 4

5 Mdeling Prblem Examples Nrth Flrida Mdel (SRWMD) Presented as well calibrated Clser inspectin big errrs errr > 5 feet: 207 wells errr > 10 feet: 63 wells errr > 20 feet 13 wells 5

6 Mdeling Prblem Examples Inaccurate simulatin f spring and river flws Flws simulated at expense f head Over-estimates head in rivers by feet 6

7 Mdeling Prblem Examples Simulated permeabilities t high Elevated permeabilities required because cnduits nt simulated times higher than bserved and published values Distributin nt gelgically defensible 7

8 Mdeling Prblem Examples - Result Mathematics invalid ver half f mdel dmain 8

9 Mdeling Prblem Examples - Result Under-predicts Gainesville cne f depressin by 30+ feet 9

10 Mdeling Prblem Examples - Result Under-predicts Gainesville zne f influence by 100+ square miles 10

11 Mdeling Prblem Examples - Result Ttal Simulated UFA Flux 13,130 CFS % Rivers & Springs 7,163 55% Over-estimates ttal flw thrugh aquifer Under-estimates impacts f pumping Wells 1,005 8% Castal Bundaries 1,809 14% Nn-castal Bundaries 3,153 24% Nn-verifiable Bundaries = 38% f Ttal UFA Flux 11

12 Imprved Mdeling Apprach Hybrid Mdel Simulates Cnduit & Matrix Flw Darcy flw in matrix Pipe flw in cnduits Cnduit lcatins and dimensins estimated thrugh mdel calibratin Dramatic imprvement in calibratin 12

13 Imprved Mdeling Apprach Hybrid Mdel Hybrid Mdel EPM Mdel 13

14 Imprved Mdeling Apprach Hybrid Mdel Substantially mre reliable mathematics 14

15 Imprved Mdeling Apprach Hybrid Mdel Reasnably Simulate Springsheds 15

16 Imprved Mdeling Apprach Hybrid Mdel Reasnably Simulate Impacts f Grundwater Pumping 16

17 Wakulla Area Hydrgelgy KARST CONDUITS >1 mile/day >1 mile/day ~1/2 mile/day ~1000 ft/day ~1000 ft/day Western Wdville Karst Plain Flw is fast in caves and in surrunding aquifer (caves t small t map) Large part f Wakulla s discharge is inflw frm swallets (surface water) Wakulla & Spring Creek are cnnected Spring Creek began reversing fr appreciable duratins in 2006 Spring Creek reverses nw every summer fr weeks - mnths We re lsing the largest spring in Flrida & the assciated fresh water that flws t the Gulf f Mexic estuaries 17

18 Spring Creek Saltwater Intrusin Wakulla Cave Punch Bwl Sink ~ 3 miles Spring Creek 18

19 Wakulla Reginal Grundwater Flw Mdel

20 Wakulla Mdel - Histry Began in 2002 with Rdney DeHan and FGS Can we build a better muse trap? Identify technlgies that wuld accmmdate cnduit flw Hybrid Mdeling Technlgy established in early 1990 s Built n existing mdels largely limited t Flrida Wdville Karst Plain Expanded reginal scpe in 2009 Allw mdel t define springshed bundaries internally Used cmpiled pumping and gelgic datasets Learned f much mre pumping cmpiled all pumping data frm Flrida & Gergia frced reinterpretatin f gelgy cmpiled frm mre available data 2012 new datasets cmpiled and presented mdel needs t be revised shuld address technlgies develped fr the Santa Fe Mdel 20

21 2010 Mdel Results Ptentimetric Surface Velcities 21

22 2010 Mdel Framewrk ~900 wells and brehles 22

23 Revised Gelgy 2000 additinal brelgs 2010 Mdel Miller 1986 Miller Mdel - added Herrick 1961 McFadden & Others 1986 FL LithPrg Database 23

24 Agricultural Pumping Natinal Envirnmentally Sund Prductin Agriculture Labratry (NESPAL) - University f Gergia's Cllege f Agricultural and Envirnmental Sciences Gergia EPD NWFWMD SRWMD GA: 183 MGD Cntributing Cunties / 93 MGD Mdel Dmain FL: 29 MGD Cntributing Cunties / 21 MGD Mdel Dmain 24

25 Municipal Pumping GA: Fanning & Trent 2009 FL: Maralla 2009 FL: NWFWMD GA: 54 MGD Cntributing Cunties FL: 24 MGD Cntributing Cunties 25

26 Revised Hydrstratigraphic Framewrk Expanded Mdel t bttm f Oldsmar r equivalent 9 mdel layers (expanded frm 5) Divisins set t describe lateral and vertical hetergeneity in Flridan aquifer system units GWM LAYER AGE HIGH PERM LOW PERM NOTE 1 Pst Micene Undif. sand & clay Micene Altamaha Hawthrne Cntinuus, vertical K will define where Hawthrn present 2 Micene Chattahchee / Tampa / St. Marks Discntinuus, all Micene limestnes where present 3 Upper Oligcene Suwannee Discntinuus, all Suwannee where present 4 Lwer Oligcene Marianna / Undif. Discntinuus, all Marianna where present 5 Upper Late Ecene Ocala Cper Marl Discntinuus, all Ocala where present 6 Lwer Late Ecene Wilsn Undif. / Barnwell 7 Upper Middle Ecene Avn Park Lisbn 8 Lwer Middle Ecene Lake City Tallahatta 9 Early Ecene Oldsmar HTGB Discntinuus, hrizntal K will define Wilsn / Undifferentiated divisin Cntinuus, hrizntal K will define Avn Park / Lisbn divisin Cntinuus, hrizntal K will define Lake City / Tallahatta divisin Cntinuus, hrizntal K will define Oldsmar / HTGB divisin - Palecene Cedar Key Cedar Key Tp f the layer is bttm slice f mdel 26

27 Revised Framewrk Early Ecene Layer 27

28 Revised Gelgy Lwer Middle Ecene Layer 28

29 Revised Gelgy Upper Middle Ecene Layer 29

30 Revised Gelgy Lwer Late Ecene Layer 30

31 Revised Gelgy Upper Late Ecene Layer 31

32 Revised Gelgy Lwer Oligcene Layer 32

33 Revised Gelgy Upper Oligcene Layer 33

34 Cmpletin Tasks & Objectives Revise calibratin datasets Typically use ne perid Wuld like t use tw (high-water & lw-water) based n benefits bserved in the Santa Fe Mdel Revise mdel framewrk with new gelgic delineatins Calibrate Mdel Simultaneus calibratin t tw datasets Adapt glbal parameter estimatin (ptimizatin) cde t hybrid mdel Develp scenari analyses Impacts f pumping (GA vs FL) Impacts f sea-level rise Timeline: 6 mnths t 1 year depending n calibratin apprach 34

35 Prbable Applicatins f Cmpleted Mdel Predict impacts f grundwater extractin n spring flws Simulate springshed bundaries and hw they interact Simulate specific spring discharges Simulate magnitude and spatial lcatin f pumping Simulate specific grundwater extractins Predict impacts f changing recharge cnditins n spring flws Simulate land use and land use changes Simulate 3D hydrstratigraphic framewrk Map spring and well vulnerability t cntaminatin Simulate grundwater flw patterns t springs Simulate grundwater velcities Identify surces f cntaminatin t springs 35

36 Thanks fr Listening Acknwledgements Flrida Gelgical Survey Rdney DeHan, Jn Arthur, Sctt Dyer, Tm Greenhalgh, Harley Means FGS Staff Applied research t slve prblems The Cca-Cla Cmpany Vested interest in sustained clean freshwater discharge t the Western Santa Fe River Diminished water quality & quantity diminishes ur business and their brand 36