analysis of groundwater/surface water interaction at the site scale babcock ranch community...
TRANSCRIPT
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
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.
Location
West Coast of Florida
North of Ft. Myers.
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
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
Drainage Plan
Groundwater/Surface Water Interaction – Babcock Ranch 6
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
Lee County Settlement Agreement
Groundwater/Surface Water Interaction – Babcock Ranch 7
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
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
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
Grid and Development Plan
Groundwater/Surface Water Interaction – Babcock Ranch 10
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
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
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
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
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
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
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
PRMS Results
Groundwater/Surface Water Interaction – Babcock Ranch 17
November 2007 Rainfall August 2007 Rainfall
PRMS Results
Groundwater/Surface Water Interaction – Babcock Ranch 18
August 2007 Overland Runoff August 2007 Cascade Flow (in/mon)
PRMS Results
Groundwater/Surface Water Interaction – Babcock Ranch 19
August 2007 Infiltration August 2007 GW Recharge (after ET) - Current
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)
Groundwater Submodel
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
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
Existing Structures
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
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
GW Calibration
Groundwater/Surface Water Interaction – Babcock Ranch 27
Simulated average wet season heads versus observed
GSFLOW Streamflow Calibration Results
Groundwater/Surface Water Interaction – Babcock Ranch 28
Simulated (blue) and Observed (red) flows at three key gages
Daily Rainfall WY2006
JEI-570
JEI-567
JEI-569
Wetland Stage Calibration Results
Groundwater/Surface Water Interaction – Babcock Ranch 29
Simulated (blue) and Observed (red) stage at three key wetlands
JEI-509
JEI-1476
JEI-510
GSFLOW Results
Groundwater/Surface Water Interaction – Babcock Ranch 30
August 18, 2008 Streamflow August 19, 2008 Streamflow
GSFLOW Results
Groundwater/Surface Water Interaction – Babcock Ranch 31
Best seen as animation.
Shows rainfall, heads, streamflow, wetland and lake depth
Click for Animation
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
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
GSFLOW Prediction Results
Groundwater/Surface Water Interaction – Babcock Ranch 34
Simulated flow under current and post-development conditions
JEI-570
JEI-567
JEI-569
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
Area 3
Area 1 (Curry Lake)
Area 2
Wetland Stage Hydrographs Natural, Post-development, and Current Conditions
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
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?