Application of the comprehensive aquatic system model(CASM-4D) in support of ecosystem restoration

Steven M. Bartell1,2

1Cardno, Inc., Greenback, TN2Department of Ecology and Evolutionary Biology,University of Tennessee, Knoxville, TN

• Describe the CASM• Introduce the SAND model• Present SAND-CASM integration

to address ecosystem restoration

Purpose

Special AcknowledgmentsCraig FischenichBobby McComasERDC, Vicksburg, MS forSAND modeling

Benthic Insects

Decomposers

Benthic Omnivorous Fish

Benthic InvertebratesPeriphyton

Macrophytes

Benthic PiscivorousFish

Planktivorous Fish

ZooplanktonPhytoplankton

Dissolved and Particulate

CarbonLight

NutrientsDINDIPSi

Piscivorous Fish

TemperatureDepthVelocitySalinityTISPOC, DOCDissolved O2 Emergents

Direct mortalityToxicity dataChemical concentrations

Comprehensive Aquatic Systems Model – CASM-4D

What is the CASM? How does it work?

Coastal Louisiana example

Spatial domain Modeled nodes

Each node

CASM-MRGOBartell et al. 2010 Food web is embedded

in each layer of eachnode

Photosynthesis, P

Sinking, S

Respiration, R

Mortality, M

Grazing, G

Phytoplankton

ΔB = P – (R + M + S) – G + (I - O)

Inflow, I Outflow, scour, O

Periphyton

Macrophytes

Emergentaquatic plants

Primary producer bioenergetics

Modeling aquatic plant populations

Biomass: gC/m2

Flows: gC/m2/d

Modeling fish and invertebrate populations

C

R,AU

GΔB = C - F - (R + A) - U - G - M - P

F

M,P

Biomass: gC/m2

Flows: gC/m2/d

Habitat quality effects on population-specific modeled growth

Producer habitat modifierHmod = F (hsalinity, hdepth, hvelocity)

Consumer habitat modifierHmod = F(hDO, hdepth, hsalinity, hvelocity)

For each species, node, and time step:dB/dt = r Hmod B,

where, r is the overall growth rate determinedby the bioenergetics

0

1.0

h (F)

Factorx1 x2 x3 x4

x1 = lower thresholdx2-x3 = optimal rangex4 = upper threshold

Environmental inputs define habitat quality and distribution

Biological/EcologicalDaily values of population biomass (gC/m2)Community diversitySystem-level N and P assimilationOxygen producedCarbon sequestration

EnvironmentalDissolved oxygenDIN, DIP, Si, TIS, POC, DOC

Ecological RisksPopulation, community, ecosystem effects

CASM-4D Outputs

SAND V3: Sediment And Nutrient Diversion Model - Planform

Point of discharge

10 km

20 km

Sediment accumulation• Discharge, velocity• Suspended sediment concentrations• Particle size• Roughness

Example has 50 spatial zones across the model domain

SAND V3: Sediment And Nutrient Diversion Model

At+1 = At + δAt + Ased

where,At+1 = marsh area at t+1At = marsh area at tδ = percent change due to sea-level rise, erosion,

subsidenceAsed = benefit to marsh area of adding sediments

Example SAND input river discharge – 25 y

• Daily discharge • Suspended sediment load• Nutrient concentration

SAND annual sediment deposition (feet) – selected zones

• Depends upon discharge, velocity, particle size, bathymetry,and sediment consolidation

• Value of zero means maximum amount of land-building achieved for the zone

SAND modeled changes in land cover – entire domain

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

8 16 24 32 40 48

Mean depth (m) - initialMean depth - final (m)

Node

SAND modeled changes in mean zone depth – after 25 y

Zone

SAND V3 CASM-4D

Water depth

Percent land

Dissolvedinorganic N

Initial conditions:• Land cover • Bathymetry

Daily values:• Discharge• Suspended sediments• Nitrogen

Distribution and biomass:

Aquatic plants

Aquatic invertebrates

Fish

Risks and benefits of ecosystem restoration

Use an integrated modeling approach to examineecological implications of sediment management

SAND-CASM modeled changes in aquatic plants – entire domain

-30

-20

-10

0

10

20

30

40

50

4 8 12 16 20 24

PhytoplanktonPeriphytonSAVEmergent aquatic plants

Year

Results reflect• Population-specific depth preferences• Population-specific responses to DIN loading• Overall increase of land-cover, less open water

SAND-CASM modeled changes in benthic invertebrates – entire domain

0

10

20

30

40

50

4 8 12 16 20 24

OystersBlue crabBrown shrimpWhite shrimp

Year

• Population-specific depth preferences• Indirect food web effects ,

e.g., increased periphyton production

0

1.0

h (F)

Factorx1 x2 x3 x4

Relevance to GEER:

• Managed flows• Beneficial sediment use• Temperature• Salinity• Nutrients (N, P)• Combined factors

Thank you.

Governing equations

Aquatic plants

Fish and invertebrates

• First-order linear differential equations with nonlinear terms• One instance of the governing equation for each population• Equations interrelated by trophic interaction terms

Privileged and Confidential

Integration of CASM-4D with physical models

Hydrodynamic and Hydraulic Model Outputs- depth- current velocity- suspended sediments- temperature- salinity

time seriesof inputvalues

CASM-4D

Scale differences between H&H modelsand CASM routinely requires somespatial and or temporal averaging…

Privileged and Confidential