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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
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
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
200
210/220
110
120/160
300-330
140/150
100
200
210/220
110
120/160
300-330
140/150
100
200
210/220
110
120/160
300-330
140/150
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