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November 17, 2016 Ravi Nalamothu P.E.
HSW Engineering Inc.
Floodplain Habitat Area Analysis using GIS
Outline
Minimum Flows and Levels Floodplain Analysis - Methodology Case Studies
Minimum Flows and Levels (MFLs)
Statutory directive included in the Water Resources Act (1972)
Directs each WMDs to establish MFLs for surface water bodies, and aquifers
MFL Definition
Limit at which further withdrawals would be “significantly harmful” to the water resources or ecology of the area
Must be based on “best available” information Periodic Revision
Districts establish MFLs to:
Comply with Florida Statute 373.042 (1)(a)&(b) Protect water resource and ecology while permitting water
use (WUPs)
“Significant harm”
Statute does not quantify “Significant harm” Quantifying “Significant harm”
No more than a certain percent reduction in available habitat
“Significant harm” - Allowable percent reductions in resources of interest (WRVs) Recreation (Boat passage) Fish Passage Fish and Wildlife Habitat Floodplain Habitat Estuarine Habitat
MFL-Conceptual Approach
Floodplain Inundation Analysis
Objective - Flow reduction associated with 15% reduction in Wetland Community Inundation Area (WCIA) Flow available for withdrawal Water Elevations
• Hydraulic Models (HEC-RAS) • Hydrodynamic Models (EFDC)
Methodology
Generate Water Surface TINs
TIN – LiDAR = Inundation Polygon
Wetland Shapefile + Inundation polygon = Wetland Community Inundation Area (WCIA)
Aucilla River-SRWMD
Aucilla River
0
2
4
6
8
10
12
14
0 500 1000 1500 2000 2500 3000 3500
Inun
datio
n Ar
ea (S
q. m
iles)
Flow (cfs))
Wetland Inundation Area (Sq. miles) vs Flow
Floodplain Swamp Cypress
Mixed Wetland hardwoods Mixed Scrub-Shrub Wetland
Total Wetland
15% Area Reduction and 17% Flow Reduction
Upper Suwannee River-SRWMD
6170 Mixed Wetland Hardwoods
6130 Gum Swamps
6300 Wetland Forested Mixed
6210 Cypress
Inundation Area
Upper Suwannee River
0
1
2
3
4
5
6
7
8
9
10
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12,000
Are
a, m
i2
Flow, cfs
Wetland FLUCCS Code Area versus Flow
6130: Gum Swamps
6170: Mixed Wetland Hardwoods
6210: Cypress
6300: Wetland Forested Mixed
Total Wetland FLUCCS
Inflection Area
15% Area Reduction and 7.8% Flow Reduction
Tangent Line
Lower Peace River
Example
CLC shapefile + Inundation polygon = Wetland Community Inundation Area (WCIA)
Water Surface TIN – LiDAR = Inundation Polygon
Rainbow River
Wetlands-Rainbow River
0
50
100
150
200
250
Area
(acr
es)
HEC-RAS Rainbow River
Elevation >31.3 ft
RS 4.85
RS 4.85
0 200 400 600 800 1000 1200 1400 16018
20
22
24
26
28
30
32
34
36 Section: 2015_128 Source: 2015 Bathymetry & 2003 DEM
Station (ft)
Elev
atio
n (ft
)
Le gen d
W S F 15S 15W S F 15S 14
W S F 15S 13W S F 15S 12
W S F 15S 11W S F 15S 10
W S F 14S 15W S F 15S 9
W S F 15S 8W S F 15S 7W S F 15S 6
W S F 15S 5W S F 15S 4
W S F 13S 15W S F 14S 14
W S F 15S 3W S F 15S 2W S F 14S 13
W S F 14S 12W S F 15S 1
W S F 14S 11W S F 13S 14
W S F 14S 10W S F 12S 15
W S F 14S 9W S F 13S 13W S F 14S 8
W S F 13S 12W S F 14S 7
W S F 14S 6W S F 13S 11
W S F 14S 5W S F 14S 4
W S F 14S 3W S F 13S 10W S F 14S 2
W S F 13S 9W S F 11S 15
W S F 12S 14W S F 13S 8
W S F 13S 7W S F 14S 1
W S F 13S 6W S F 13S 5W S F 12S 13
W S F 13S 4W S F 13S 3
W S F 10S 15W S F 12S 12
W S F 13S 2W S F 12S 11
W S F 9S1 5W S F 13S 1
W S F 11S 14
W S F 12S 10W S F 12S 9
W S F 12S 8W S F 12S 7
W S F 11S 13W S F 8S1 5
W S F 12S 6W S F 11S 12W S F 12S 5
W S F 10S 14W S F 12S 4
W S F 12S 3W S F 11S 11
W S F 7S1 5W S F 12S 2
W S F 10S 13W S F 11S 10W S F 9S1 4
W S F 11S 9W S F 10S 12
W S F 12S 1W S F 6S1 5
W S F 11S 8W S F 11S 7
W S F 5S1 5W S F 10S 11W S F 11S 6
W S F 9S1 3W S F 8S1 4
W S F 11S 5W S F 4S1 5
W S F 11S 4W S F 9S1 2W S F 10S 10
W S F 11S 3W S F 10S 9
W S F 11S 2W S F 9S1 1
W S F 3S1 5W S F 10S 8
W S F 8S1 3W S F 10S 7W S F 7S1 4
W S F 10S 6W S F 9S1 0
W S F 8S1 2W S F 11S 1
W S F 2S1 5W S F 10S 5
W S F 9S9W S F 10S 4W S F 10S 3
W S F 7S1 3W S F 9S8
W S F 8S1 1W S F 6S1 4
W S F 1S1 5W S F 9S7
W S F 10S 2W S F 7S1 2W S F 9S6
W S F 8S1 0W S F 5S1 4
W S F 9S5W S F 9S4
W S F 8S9W S F 10S 1
W S F 7S1 1W S F 9S3W S F 6S1 3
W S F 4S1 4W S F 8S8
W S F 9S2W S F 8S7
W S F 6S1 2W S F 7S1 0
W S F 8S6W S F 5S1 3W S F 3S1 4
W S F 7S9W S F 8S5
W S F 5S1 2W S F 9S1
W S F 8S4W S F 4S1 3
W S F 6S1 1W S F 7S8W S F 8S3
W S F 7S7W S F 4S1 2
W S F 8S2W S F 7S6
W S F 5S1 1W S F 6S1 0
W S F 2S1 4W S F 3S1 3W S F 7S5
W S F 6S9W S F 7S4
W S F 4S1 1W S F 8S1
W S F 5S1 0W S F 7S3
W S F 1S1 4W S F 3S1 2W S F 6S8
W S F 6S7W S F 7S2
W S F 5S9W S F 2S1 3
W S F 4S1 0W S F 6S6W S F 5S8
W S F 3S1 1W S F 5S7
W S F 4S9W S F 6S5
W S F 2S1 2W S F 7S1
W S F 6S4W S F 1S1 3W S F 5S6
W S F 4S8W S F 6S3
W S F 3S1 0W S F 4S7
W S F 6S2W S F 5S5
W S F 1S1 2W S F 5S4W S F 4S6
W S F 2S1 1W S F 3S9
W S F 5S3W S F 3S8
W S F 4S5W S F 5S2
W S F 4S4W S F 3S7W S F 6S1
W S F 1S1 1W S F 2S1 0
W S F 4S3W S F 3S6
W S F 4S2W S F 2S9
W S F 5S1W S F 1S1 0W S F 3S5
W S F 3S4W S F 2S8
W S F 3S3W S F 2S7
W S F 1S9W S F 4S1
W S F 3S2W S F 2S6W S F 1S8
W S F 1S7W S F 2S5
W S F 2S4W S F 1S6
W S F 3S1W S F 2S3
W S F 2S2W S F 1S5W S F 1S4
W S F 1S3W S F 1S2
W S F 2S1W S F 1S1
G r ou ndBa nk St a
Elev 31.3 ft
TIN Extended using TIN Editor
Water Surface TIN Boundary
99% Non-Exceedance Results
Low Flow Inundation Area: 198 acres
High Flow Inundation Area: 441 acres
Area vs Flow
0
50
100
150
200
250
300
350
400
450
500 550 600 650 700 750 800 850 900 950 1000
Area
(acr
es)
Flow (cfs)
15.7%
63.8%
15% Area reduction and 18% Flow reduction
Conclusion
GIS used to look at potential change in habitat area for the entire river ArcGIS Tools
• 3D analyst • TIN editor • Model Builder for analysis automation
Questions?
Funding Agencies: Southwest Florida Water Management District Suwannee River Water Management District
