Why do we need to model the
Lower Passaic – Newark Bay?
December 19, 2011
Ed Garland1, Eugenia Naranjo2
1- HDR|HydroQual 2-USEPA
Models
1. Why do we need them?
– For sediment sites, for Passaic
2. What are they doing?
3. Why does modeling take so long?
4. Initial results of Lower Passaic Modeling
study
A model is a schematic
CARP
Model
Grid
16,000 water
column
and 16,000
sediment cells
With a model we can:
PREDICT
EVALUATE
&ASSESS
• Future Conditions
• Impact of Extreme Events
• How would Newark Bay
sediment affect the
remediated Passaic?
• Impact of a storm on a ‘cap’
•
•
effects of “no-action” and
“complete removal or other
remediation alternatives
How resuspension from
dredging might affect Newark
Bay
Sampling Locations vs Model
It’s not possible to measure everything
Data
Collected with
Moored
Instruments
What if we don’t use a model?
• We would not be able to show what be
may achieved after millions of $$ are
spent
• We would not be able to predict what
would happen to the environment if we
do nothing
• All of this uncertainty increases the
likelihood that the clean-up plan will be
challenged in court
Modeling Framework
Hydrodynamics
WATER
movement
Sediment
Transport
Particles
movement
Contaminant
Transport & Fate
RCATOX
Contaminants
attached to
particles
Risk
Assessment
Passaic,
Hackensack,
Newark Bay,
NYNY-NJ Harbor
Sediment Transport
44 x 243
(10,692 grid cells)
Top Active zone
divided into 10 layers
A partially mixed estuary
based on Dyer, 1972; Pethick, 1984
Low River Flow
Range of Salinity
Front Location
Dundee Dam
Low Flow Input
from Passaic River
Downstream
Transport of
River Material
Erosion and Deposition
(Mixing) of Material
Due to Estuarine
Processes
Newark Bay
Lower Energy Region
– Less Erosion and
Deposition
Estuarine
Exchange
with
Newark Bay
Net Upstream
Transport of Bay
Material
Physical Water Column
Monitoring Period
Model Data Comparisons
Movement of Salt Front
SHOW
SALINITY
MOVIE
Depth_TSS_Salt.exe
March 2010 High Flow:
Comparing model results to data
Sediment Bed Elevation Changes:
Comparing model results to data
3) Why does it take so long
• To correctly develop and apply a model is time
consuming
• A model is not reality, the modeler is trying to
reproduce what is happening in the real world
–
–
–
–
–
Model calibration
Needs to understand the data
Create a or understanding of the system with the data
Needs to “translate” data into “model language
Long process
Despite super fast computers, heavy computations
per grid/layer
We are making long term calculations/predictions
Now what?
How does this information get transferred?
Hydrodynamic Model
Flow
Tides
Sediment Transport Model
Information Transfer
Sediments
Current Velocity
Salinity
Sediment Bed
Organic
Carbon
Suspended Solids
Concentration
Deposition
Burial
Contaminant Fate Model
Scour
Chemical
Loads
Particulate and
Dissolved
Chemical
Concentrations
Part and Diss
Chemical
Concentrations
QUESTIONS