River Sediment Calibration Rules

Gary Shenk

5/3/05

Modeling Subcommittee

Schedule

• Sediment calibration must be done by June 1.

• Nutrient Calibration must be done by August 1.

• Refinements will follow over the next 18 months.

Calibration Method

• Flow– Automatic calibration method developed

• Edge-of-Field Sediment– Automatic calibration method developed

• River Sediment– Two out of three ain’t bad– Developed calibration rules and will apply

them by hand

critz

w

eMass

1

1

River Cohesive Sediment Simulation

SuspendedSediment

Bed Storage(unlimited)

Outflow

Sco

ur

Dep

osit

ion

Inflow

1*

crit

AreaM

critz

w

eMass

1

1

River Sediment Simulation

Bed Storage(unlimited)

Dep

osit

ion

River Sediment Simulation

Bed Storage(unlimited) S

cour

1*

crit

AreaM

River Sand Simulation

Jvelocityksand }{*][

Adjustments are then made to the bed depth

Calibration Rules

• All rivers segments upstream of a calibration point have identical parameters

• For nested rivers, this applies only to rivers downstream of any upstream gages.

Remington

Robinson

Rappahannock

1

Uncalibrated

Stau 97 percentileCtau 93SW .001 inches/secCW .0001 CM = 1 lb/ft^2/daySM = 1KS = .003 empiricalES = 4

High flow in the ballpark, but low flow is a problem. Lowest concentrations are mostly VSS, which is not yet simulated and are at LOD in the observed

Stau 97Ctau 93SW .001CW .0001CM = 1SM = 1KS = 3ES = 3

To deal with the lack of VSS in the simulation, use SAND to make the low concentrations work out. This can be easily reversed when VSS are simulated

Stau 99Ctau 96SW .001CW .0001CM = 1SM = 1KS = 3ES = 3

Reduce the frequency of scour to deal with over-simulation

Stau 99Ctau 96SW .001CW .0001CM = .5SM = .5KS = 3ES = 3

Reduce the effect of scour to deal with over-simulation

Stau 99.5Ctau 98SW .001CW .0001CM = .5SM = .5KS = 2.8ES = 3

Tighten up the simulation

Issues with simulation

• Low values dominate the CFD, but they are not meaningful from:– A load standpoint– An accuracy of observation standpoint– Simulation standpoint (no VSS)

• Flow not perfectly calibrated– If peak is missed by a day, then the

concentration simulation should not match the observed.

‘Windowed’ comparison

• If simulated or observed value is below 10 mg/l set it to 10 mg/l.

• Check simulation for 24 hours before and after observation and set simulated value to point closest to observation.

Of the highest observed and simulated peaks at all calibration stations, almost as many peaks occurred one day apart, but few occurred on two days apart

One day apart – 83% of the same day figure

Two days apart – 19% of the same day figure

I

Reported Error

Stau 97Ctau 93SW .001CW .0001CM = 1SM = 1KS = .003ES = 4

Starting point

Stau 97Ctau 93SW .001CW .0001CM = 1SM = 1KS = 3ES = 3

Sand Calibration

Stau 99Ctau 96SW .001CW .0001CM = 1SM = 1KS = 3ES = 3

Reduce Frequency of Scour

Stau 99Ctau 96SW .001CW .0001CM = .5SM = .5KS = 3ES = 3

Reduce effect of scour

Stau 99.5Ctau 98SW .001CW .0001CM = .5SM = .5KS = 2.8ES = 3

Tighten up calibration

paired daily values of flow X conc

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7 8

simulated load

ob

serv

ed lo

ad

obs load

1:01

Hope for automation

• Separate out sections of the CFD– Low part: sand - VSS– Highest part: silt– Mid-high part: clay

• PEST– Few parameters– Short run time ~ 1-2 minutes

Plan

• Following calibration rules, team will calibrate all stations this month.– Jing Wu – Susquehanna– Jason Pope – Southern Rivers– ICPRB – Potomac

• Set up nutrient calibration– Jeff Raffensperger – observed data and input– Gary Shenk – model simulation setup– CBP nutrient team – nutrient input data