Coastal_Ecological_Flows_Working_Group_Update

Update for Coastal
Ecological Flows Working
Group
Bob Christian
July 17, 2013
Working Group Membership
•Bob Christian ECU
•Eban Bean ECU
•Dean Carpenter APNEP
•Scott Ensign Consulting
•Mike Griffin ECU
•Kevin Hart NC DMF
•Mike O'Driscoll ECU
•Mike Piehler UNC IMS
•Judy Ratcliffe Natural Heritage
•Fritz Rhode NOAA
•Bennett Wynne NC Wildlife Resources

Overall Objectives
•Assess applicability of previous coastal work
–Other states
–Greenville
•Develop stream typology
•Advance spatial modeling and mapping
•Establish relevant ecological and biological dependencies on flow
•Develop frameworks for potential coastal EF criteria and protocols if possible
•Identify factors limiting EF protocols and needed research within coastal systems

by Scott Ensign
Link of Stream Typology & Potential EF Determination
Origin Slope EF determinant
Discharge &
Habitat
Downstream
Salinity

Overbank Flow
Piedmont Medium
gradient
X X
Upper Coastal
Plain
Medium
gradient
X X
Upper Coastal
Plain
Low gradient X X X
Lower Coastal
Plain
Low gradient X X X
Lower Coastal
Plain

Wind or tidal
driven flow
X X
Eban Bean and
Mike Griffin
Natural vs.
Engineered
Natural
Engineered
(Canal/Ditch)
Channel Slopes
(with aid from Kimberly Meitzen)
•Elevation change over reach length
–average reach slope
•Range:
–TNC: 0.00001% – 2.9%
•Distribution:
–TNC: Most 0.00001% -- 2%
Channel Slope Threshold:
0.02 m/m
Channel Slope Threshold:
0.005 m/m
Channel Slope Threshold:
0.002 m/m
Channel Slope Threshold:
0.001 m/m
Channel Slope Threshold:
0.0002 m/m
Channel Slope
Threshold: 0.0001 m/m
Slope threshold for typology
•Low slope = <0.001 m/m
•Medium slope = >0.001m/m to 0.005 m/m

•Appears to relate to stream order, catchment
size

by Scott Ensign
Objectives for July 15
•Assess applicability of previous coastal work
–Other states
–Greenville
•Develop stream typology
•Advance spatial modeling and mapping
•Establish relevant ecological and biological dependencies on flow
•Develop frameworks for potential coastal EF criteria and protocols if possible
•Identify factors limiting EF protocols and needed research within coastal systems

Link of Stream Typology & Potential EF Determination
Origin Slope EF determinant
Discharge &
Habitat
Downstream
Salinity

Overbank Flow
Piedmont Medium
gradient
X X
Upper Coastal
Plain
Medium
gradient
X X
Upper Coastal
Plain
Low gradient X X X
Lower Coastal
Plain
Low gradient X X X
Lower Coastal
Plain

Wind or tidal
driven flow
X X
Special Coastal Plain Considerations
•Because of flatness, low elevation and proximity to the sea
–Ground water and surface water are closely linked
•Ground water withdraw can be important to surface water flow
•Ground water withdraw may alter inundation patterns of low
order streams
•Ground water may be shunted into surface water for agriculture
–Flow is closely linked to water quality
•Salinity
•Dissolved oxygen
–Stage is not necessarily well defined by freshwater flow

Key nekton
•Species are often different than those found in inland waters or having different ecology from that inland.
–Examples (Some require Fisheries Management Plans involving flows)
•Anadromous fish (upstream spawning)
–Blueback herring and alewife (under consideration for endangered status)
–American shad
–Atlantic sturgeon (endangered)
–Shortnose sturgeon (endangered)
–Striped bass (stock status – concern)
•Catadromous fish (marine spawning)- eel – (stock status - depleted)
•Estuarine species – some of the common low-salinity species that occur in river systems: southern flounder, Atlantic croaker, spot, menhaden, bay anchovy, blue crab, white shrimp, striped mullet
Anadromous fish
•Ecologically and economically important
•Large database for State
•Spawning flows important
•Flows during larval and juvenile growth and
development equally important
–not simply spawning season
–position of salt “wedge” important
•Habitat suitability models available

Table 2.4. Physical spawning (adult) and egg development requirements for resident freshwater and anadromous fishes inhabiting coastal North Carolina.

Species
Salinity (ppt) Temperature (C) Dissolved oxygen (mg/l) Flow (cm/s) Other parameters
Adult Spawn/ Egg Adult Spawn/ Egg Adult Spawn/ Egg Spawning Spawn/ Egg
Alewife [S] 0-5 [S] 0-5 [O] 0-2 [S] 11-28 [O] 17-21 [S] >3.6 [S] >4 [O] slow current
[S] Suspended solids <1000
mg/l
American shad [S] 0-18 [S] 0-18 [S] 10-30 [S] 13.0-26.0 [S] >5 [S] 30-90
Blueback herring [S] 0-5 [S] 0-22 [O] 0-2 [S] 14-26 [O] 20-24 [S] >5 [O] strong current
[S]
Suspended solids <1000
mg/l
Striped bass [S] 0-5 [S] 0.5-10 [S] 20-22
[S] 12-24,
[O] ~18-
22
[S] >5 [S] 30.5-500, [O]
100-200
Yellow
perch [S] 0-13 [S] 0-2 [S] 6-30 [S] >5
[S]
Suspended
solids <1000 mg/l
White perch [S] 5-18 [S] 0-2 [S] 10-30 [S] 12-20 [S] >5
[S]
Suspended solids <100
mg/l
Sturgeon,
Atlantic
[S] 0 to
>30 [S] 0-5 [S] 0 to
>30 [S] 11-20
Sturgeon,
Shortnose
[S] 0 to
>30 [S] 0-5 [S] 0 to
>30 [S] 5-15
[S] = Suitable, and [O] = Optimum

Physical factors
and flow
influence select
species and life
history stages
Vegetation (foundation species)
•Riparian swamp trees
–Important flow conditions:
•Overbank flow frequency, timing and duration
•Salinity
•DO
•Submerged aquatic vegetation
–Important flow conditions:
•Salinity
•DO
Link of Stream Typology & Potentially Key
Assemblages
Origin Slope Assemblage
Anadromous
Fish
Resident fish

Vegetation
(Foundation
species)
Piedmont Medium
gradient
X
Upper Coastal
Plain
Medium
gradient
X
Upper Coastal
Plain
Low gradient X X
Lower Coastal
Plain
Low gradient X X
Lower Coastal
Plain

Wind or tidal
driven flow
X X
Research Needs
1.Juvenile abundance indices vs. flow and
salinity/conductivity
2.Salinity distribution across coastal plain
3.Quantification of stream typology classes
4.Roanoke slabshell mussel distribution and abundance as
representative of benthos
5.Hydrologic metrics and characteristics of coastal
streams
6.Determine reference flow regimes for each river basin
7.Balance of withdraws from and discharges to coasta;
streams
Where are we?
•Not far enough for a “Trial balloon.”
•There is a need for a coastal plain approach at
least for coastal plain originating, low gradient
and tidally dominated streams
•Stage may be the tracking hydrologic property
rather than flow
•Flow and water quality cannot be separated
•Different key assemblages may be needed for
different stream classes