Analysis of Groundwater/Surface Water Interaction at the Site Scale Babcock Ranch Community Development Lee County, Florida
1. Analysis of Groundwater/Surface Water
Interaction at the Site Scale
Babcock Ranch Community Development
Lee County, Florida
E.J. Wexler, P.J. Thompson
G.F. Rawl, Dirk Kassenaar
IAH-CNC 2015
Waterloo, ON
November 4, 2015
2. Babcock Ranch Development
Groundwater/Surface Water Interaction – Babcock Ranch 2
Land purchased in 1914
Located on Florida west coast
Straddles Lee and Charlotte Counties
Babcock Ranch City to have 45,000
residents
First fully solar-powered city in U.S.
4. Babcock Ranch Location
Groundwater/Surface Water Interaction – Babcock Ranch 4
Site located north of
Caloosahatchee River near
Ft. Meyers, FL
Telegraph Swamp is a key
wetland feature
Sold to state in 2006 as a
Nature Preserve
1100 km2 Study Area
includes Babcock Ranch,
Telegraph Swamp and
subwatersheds to either
side
Babcock
Ranch
Model Boundary
Callosahatchee River
Telegraph
Swamp
5. Conceptual Plan
Groundwater/Surface Water Interaction – Babcock Ranch 5
19,500 homes concentrated in
“development pods”.
Four residential villages and
five hamlets
Other light industry and
commercial
50% of developed area to be
left as nature reserve
6. Drainage Plan
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Runoff from developed areas
directed to stormwater lakes
Overflow to wetland preserves
Some runoff directed to treatment
marshes
Aggregate mines converted to
larger stormwater lakes
Remaining discharge to streams
going offsite
Seepage from stormwater lakes
re-hydrates wetlands
7. Lee County Settlement Agreement
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Lee County concerned about wetlands and possible flooding in Telegraph
and Trout Creek downstream of Babcock Ranch.
Wanted proof that stormwater management system will restore more
“natural” (pre-settlement) conditions
Telegraph Creek
8. Modelling Approach
Groundwater/Surface Water Interaction – Babcock Ranch 8
Integrated model needed to simulate
groundwater-fed wetlands and ET
Earthfx built an integrated GW/SW
model for:
“Current Conditions”
“Post-development” conditions - increased
imperviousness and stormwater
management
▪ “Natural Conditions” – all ditches, berms,
mines, roads removed
Compare infiltration, storm flow,
groundwater recharge, heads, and
wetland hydroperiod under each
scenario.
GSFLOW Code used for integrated Model
9. GSFLOW Code
Groundwater/Surface Water Interaction – Babcock Ranch 9
GSFLOW is a USGS code developed for
integrated GW/SW modelling
Based on MODFLOW-NWT and PRMS
(Precipitation-Runoff Modelling System)
Fully open-source, proven and very
well documented
▪ PRMS submodel handles soil moisture
accounting and groundwater recharge
▪ Groundwater submodel provides water to
soil zone in areas of shallow water table
Groundwater/surface interaction
simulated for lakes and streams PRMS Submodel in GSFLOW
10. Grid and Development Plan
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PRMS submodel was used
as a distributed model
Calculates soil water
balance for each
100 x 100 m cell.
Same grid used for
MODFLOW submodel
Overland runoff routed
between cells using
cascading flow
Runoff can re-infiltrate
downslope PRMS Submodel in GSFLOW
11. PRMS Submodel Parameters
Groundwater/Surface Water Interaction – Babcock Ranch 11
Four general categories:
▪ Topography
▪ Soil Properties
▪ Land Use/Vegetation
▪ Climate
Topography from LIDAR
and USGS data
▪ Total elevation change: 55 ft
Soil properties from
mapping
▪ % impervious, vegetation
type, CN values, cover
density based on land
use/cover mapping
Topography
12. PRMS Soil Mapping
Groundwater/Surface Water Interaction – Babcock Ranch 12
Grouped into 9 categories
▪ Mostly fine sand, but poorly
drained – B/D soils
▪ Muck/Organic soils in
wetlands
High runoff during wet
season (May-September)
due to high water table
Better drained in dry
season (October-April)
Soils
13. PRMS Land Cover
Groundwater/Surface Water Interaction – Babcock Ranch 13
FLUCS data
Natural cover is mainly
wetland, upland forest,
and rangeland
Agriculture is the primary
land use
▪ Limited urban development
in south
Cover type modified for
“post-development” and
“natural” conditions
Land Use
14. PRMS Rainfall
Groundwater/Surface Water Interaction – Babcock Ranch 14
Rainfall shows wet-season/dry
season variation
Rainfall also shows year-to-year
variation
Averages about 1370 mm/yr
Annual Rainfall
Monthly Rainfall
NEXRAD
15. PRMS PET
Groundwater/Surface Water Interaction – Babcock Ranch 15
ET is very high year-round
Averages about 1323
mm/yr
Nearly matches average
rainfall
Annual PET
Monthly PET
16. PRMS Results
Groundwater/Surface Water Interaction – Babcock Ranch 16
PRMS outputs daily values for Precipitation, Interception, ET,
Hortonian and Dunnian runoff, fast/slow interflow, infiltration,
and recharge
Easier to look at Monthly Averages
Daily Rainfall WY2006
20. PRMS Results
Groundwater/Surface Water Interaction – Babcock Ranch 20
August 2007 2007 GW Recharge - Natural
(Less RO, more ET)
August 2007 GW Recharge (after ET) – Post
(Less GW recharge due to impervious)
22. MODFLOW Calibration Targets
Groundwater/Surface Water Interaction – Babcock Ranch 22
13 significant streams
10 gages with 2-4 years
continuous data
505 wetlands represented
in current model
Structures at Curry Lake
and Telegraph Swamp
All agricultural ditches and
berms represented
Wells
23. MODFLOW Calibration Targets
Groundwater/Surface Water Interaction – Babcock Ranch 23
155 wells with water level
data
Most are in surficial aquifer
All have 2-4 years of
continuous data
Shallow wells in wetlands
used as surrogates for
wetland stage
Surface Water Features
25. Post-Development Features
Groundwater/Surface Water Interaction – Babcock Ranch 25
130 Storm Water Ponds
130 Wetland Preserves
12 Treatment Marshes
121 Structures
Added code to GSFLOW to
calculate stage/discharge for
weirs, gates, and orifices
Surface Water Features
26. GSFLOW Submodel Results
Groundwater/Surface Water Interaction – Babcock Ranch 26
Groundwater model outputs daily values for heads, lake
stage/volume, stream stage/discharge.
Data can be analyzed to determine hydroperiod.
Calibration can be done to average heads or to hydrographs
Daily Rainfall WY2006
31. GSFLOW Results
Groundwater/Surface Water Interaction – Babcock Ranch 31
Best seen as animation.
Shows rainfall, heads,
streamflow, wetland and
lake depth
Click for Animation
32. GSFLOW Results
Groundwater/Surface Water Interaction – Babcock Ranch 32
Detailed daily water budgets for each
cell for all inflow/outflow components
Averaged for monthly and annual
conditions
Averaged by basin and sub-basins
Results compared with natural and post-
construction conditions
33. GSFLOW Results
Groundwater/Surface Water Interaction – Babcock Ranch 33
Simulated wetland
hydroperiod
Ranges between 120-365
days
Blue areas are 365 days
Results compared with
natural and post-
construction conditions
35. GSFLOW Prediction Results
Groundwater/Surface Water Interaction – Babcock Ranch 35
Simulated wetland stage under current, natural, and post-
development conditions – general improvement
Area 3
Area 1 (Curry Lake)
Area 2
36. Area 3
Area 1 (Curry Lake)
Area 2
Wetland Stage Hydrographs
Natural, Post-development, and Current Conditions
37. GSFLOW Predictive Simulations
Groundwater/Surface Water Interaction – Babcock Ranch 37
Simulated 5-yr, 25-yr and 100 yr storm at JEI-570 - Improved
5 year Storm
25 year Storm
100-year Storm
Natural
Post-Development
Currrent
100-yr storm at JEI-570 under current, natural, and post-BRC conditions
38. Conclusions
Groundwater/Surface Water Interaction – Babcock Ranch 38
Integrated modelling is a
powerful tool for evaluating
natural and altered
hydrologic response
With sufficient data, very
good representations of the
groundwater and surface
water systems can be
obtained
Integrated models can
provide quantitative input
to land development/storm
water management studies
Questions?
