Hydrologic, Hydraulic, and Ecological Modeling Issues and Implementation

for the Blind River Fresh Water Diversion Project

Restore America’s Estuary ConferenceNovember 16, 2010

Michael Morgan, P.E. CFMKirk Westphal, P.E.

Ashok Bathulla, P.E. CFM

Purpose of Hydrologic and Hydraulic Modeling

Understand the project area hydrology

Quantify the movement of water through the swamp and the network of drainage canals

Evaluate alternatives to improve the hydroperiod

Confirm that proposed improvements will not have adverse flooding impacts

Study Area Hydrology

Connect Analyses to Field Conditions

Existing Land Use

Land Use Type Percent Area(%)

Forest Land 7.69Water body 0.28Wetland 53.37Cropland/Agriculture 30.58Commercial/Industrial 4.31Residential 3.04Others 0.73

ApproachConsiderations

• Existing hydrologic and hydraulic performance

• Location and magnitude of diversion flows

• Frequency of dry and wet periods

• Hydraulic residence time

• Distribution of water and nutrients

• Potential for offsite flooding

Tools

• Engineering Calculations

• Hydrologic and Hydraulic Modeling

• HEC-HMS• HEC-RAS

• Hydrodynamic Modeling

• EFDC

Analyses

• Long term, multi-year analysis to capture above average and below average precipitation conditions

• Average hydrologic conditions

• Average year

• Extreme storms

Engineering Calculations Schematic

HEC-RAS Schematic

100

330200

210

110 120

140

300

800 400

Existing Flow Patterns

Lake Maurepas Stages

Review of Lake Maurepas stages indicates that downstream conditions influence flows and stages in the study area

Feb Apr Jun Aug Oct Dec2003

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

River: BLIND RIVER Reach: BLIND RIVER 1 RS: 508.5759

Date

Sta

ge

(ft)

Legend

Stage

Blind River Flow Upstream of I-10

12 17 22 27 04 09 14 19 24 29 03Feb2003 Mar2003 Apr2003

-4000

-2000

0

2000

4000River: BLIND RIVER Reach: BLIND RIVER 3 RS: 34493.19

Time

Flow

(cfs

)

Legend

Flow

HEC-RAS simulates positive and negative flow in the Blind River, which is consistent with field observations following periods of rainfall and high water levels at Lake Maurepas

Advantages of Improved Drainage with Berm Cuts

28 02 07 12 17 22 27 02 07Aug2003 Sep2003 Oct2003

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Storage Area: 73

Time

Sta

ge (f

t)

Existing Conditions

Improved Drainage

Diversion Flow Options

Test system response with diversion flows of varying magnitude Reduce backflow from Lake Maurepas Deliver nutrients and sediment Reduce frequency of high water levels

24 01 06 11 16 21 26 31 05 10 15Feb2003 Mar2003 Apr2003

-4000

-2000

0

2000

4000

River: BLIND RIVER Reach: BLIND RIVER 3 RS: 34493.19

Time

Flow

(cfs

)

Legend

Flow - CSwGapsTst2

Flow - BRCSw500div

Flow - CSwGaps2aDiv2

Baseline

500 cfs Diversion4000 cfs Diversion

Screening Diversion Magnitude

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

0 1000 2000 3000 4000 5000

Ann

ual A

vera

ge D

iver

ted

Flow

(ac-

ft/y

r)

Total Diversion Capacity (cfs)

Existing with Berm CutsTotal Diversion Flow

Diversion to North Bridge Canal Diversion to Romeville Canal Diversion to North Bridge and Romeville Canals

050000

100000150000200000250000300000350000400000

0 1000 2000 3000 4000 5000

Ann

ual A

verg

ae I

nflo

w (a

c-ft

/yr)

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to North Bridge Canal & Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

0%

20%

40%

60%

80%

100%

0 1000 2000 3000 4000 5000

Freq

uenc

y A

bove

Lak

e M

aure

pas

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to North Bridge Canal & Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

0%10%20%30%40%50%60%70%80%90%

100%

0 1000 2000 3000 4000 5000

Dep

th E

xcee

danc

e Fr

eque

ncy

Total Diversion Capacity (cfs)

Existing with Berm Cuts

Diversion to Northbridge Canal & Romeville CanalHU1

0.5 ft

1.0 ft

1.5 ft

2.0 ft

Dryout Frequency: 0%

Total Annual Diversions

Frequency Above Lake Maurepas

Average Annual Freshwater Inflow

Water Depth Exceedence (Area 100)

Total TSS to Swamp

100

200

210/220

110

120/160

300-330

140/150

100

200

210/220

110

120/160

300-330

140/150

0.0

0.5

1.0

1.5

2.0

2.5

0 1000 2000 3000 4000 5000

Long

-Ter

m A

vera

ge W

ater

Dep

th (

ft)

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to North Bridge Canal & Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

Average Water Depth

100

200

210/220

110

120/160

300-330

140/150

Comparing Diversion Locations

0%

20%

40%

60%

80%

100%

0 1000 2000 3000 4000 5000

Freq

uenc

y A

bove

Lak

e M

aure

pas

Total Diversion Capacity (cfs)

Diversion to North Bridge Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

0%

20%

40%

60%

80%

100%

0 1000 2000 3000 4000 5000

Freq

uenc

y A

bove

Lak

e M

aure

pas

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

0%

20%

40%

60%

80%

100%

0 1000 2000 3000 4000 5000

Freq

uenc

y A

bove

Lak

e M

aure

pas

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to North Bridge Canal & Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

Diversion location and magnitude appeared to distribute benefits differently

Multiple diversion locations and rates considered in final array of alternatives

100

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210/220

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120/160

300-330

140/150

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210/220

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120/160

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140/150

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210/220

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120/160

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140/150

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110 120

140

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800

Flow Patterns With Project

Metrics for Evaluating Model Results

Annual increase in freshwater flows and volumes

Frequency of wet and dry conditions (120 days)

Hydraulic residence time Frequency of backflow

reduction Flux of nutrients, TSS, and

salinity

0.0

0.5

1.0

1.5

2.0

2.5

0 1000 2000 3000 4000 5000

Long

-Ter

m A

vera

ge W

ater

Dep

th (

ft)

Total Diversion Capacity (cfs)

Existing with Berm CutsDiversion to North Bridge Canal & Romeville Canal

HU1

HU2

HU3

HU4

HU5

HU6

HU7

Average Water Depth

100

200

210/220

110

120/160

300-330

140/150

0.0

0.5

1.0

1.5

2.0

Alternative 1 Alternative 2 Alternative 3 Alternative 4 Alternative 5 Alternative 6

TSS

Load

ing

(mm

/yr)

Scenario

Metric Analysis Summary for Average Annual TSS Loading (mm/yr)No Sea Level Rise

Alt 1 = Romeville Diversion (1,500 cfs) Alt 2 = Romeville Diversion (3,000 cfs)Alt 3 = South of Hwy 70 Bridge Diversion (1,500 cfs)Alt 4 = South of Hwy 70 Bridge Diversion(3,000 cfs)Alt 5 = Total Diversion (1,500 cfs); Romeville Diversion (750 cfs)/South of Hwy 70 Bridge Diversion (750 cfs)Alt 6 = Total Diversion (3,000 cfs); Romeville Diversion (1,500 cfs)/South of Hwy 70 Bridge Diversion (1,500 cfs)

0.0

1.0

2.0

3.0

4.0

Existing Conditions; No

Berm Cuts; Total Diversion = 0 cfs

Alternative 1 Alternative 2 Alternative 3 Alternative 4 Alternative 5 Alternative 6

Wat

er D

epth

(ft)

Scenario

Metric Analysis Summary for Average Annual Water Depth, (ft)No Sea Level Rise

100 200

210, 220 110

120, 160 300, 320, 330

140, 150

Sub-basinsAlt 1 = Romeville Diversion (1,500 cfs) Alt 2 = Romeville Diversion (3,000 cfs)Alt 3 = South of Hwy 70 Bridge Diversion (1,500 cfs)Alt 4 = South of Hwy 70 Bridge Diversion(3,000 cfs)Alt 5 = Total Diversion (1,500 cfs); Romeville Diversion (750 cfs)/South of Hwy 70 Bridge Diversion (750 cfs)Alt 6 = Total Diversion (3,000 cfs); Romeville Diversion (1,500 cfs)/South of Hwy 70 Bridge Diversion (1,500 cfs)

Addressing Hydrologic, Hydraulic and Ecological Issues for Restoration Projects Strive to develop a comprehensive

understanding of contributing processes

Allow project specific issues to drive selection of the analysis approach and tools

Connect hydrologic and hydraulic analysis with available information from multiple perspectives