and

Walter E. FrickUS EPA, Ecosystems Research Div., NERL, Athens, Georgia

Zhongfu GeNational Research Council, Athens, Georgia

Virtual Beach Progress Report

Ecosystems Research Division

Athens, Georgia, 8 March 2006

With guest

Robert A. DarnerUSGS, Columbus, Ohio

Richard WhitmanUSGS, Porter, Indiana

Meredith NeversUSGS, Porter, Indiana

Other Collaborators

Ecosystems Research Division

Athens, Georgia, 8 March 2006

Donna S. FrancyUSGS, Columbus, Ohio

Table of Contents

Frick Some basic physics of contaminated plumes Some reasons why empirical models are promising Modeling issues

Ge Statistical basis (manuscript) Demonstration of Virtual Beach

Darner USGS modeling directions

Discussion Questions Feedback

Great Lakes have beaches

Photo: Walter Frick, ©2003West Beach, IN

…and bacterial contaminations has many aspects

physical components and perspective empirical components and perspective …

Modeling Trail Creek and Kintzele Ditch

Mantha S. Phanikumar1, Lubo Liu1, and Richard L. Whitman2

1Department of Civil & Environmental Engineering, Michigan State Universtiy, East Lansing, MI 48824

2Lake Michigan Ecological Research Station, U.S. Geological Survey, Porter, IN

Kintzele Ditch

Trail Creek

Central Avenue beach

Mount Baldy beach

Physical Aspect

Plumes (Michigan City, Indiana Study)

current

Kintzele Ditch

Trail Creek

Central Avenue beach

Mount Baldy beach

current

Plumes, downcoast current

Empirical model

Rotated 67deg CCW, CA ChiP

recip. (in

)(cm

)

Rotated 67deg CCW, MB ChiP

recip. (in

)(cm

)

Mt Baldy, 2004 Field Season

Prototype Lead-in

Day 187 episodeBacteria > 100 (log 2)

antecedentupcoast flow

followed bydowncoast flow

antecedentrainfall

The Mechanics of a bacteria episodes at Central Avenue and Mount Baldy beaches(This paragraph applies to both beaches.) To understand the mechanics of a high bacterial count episode at Central Avenue Beach, first imagine that the observer is standing at the mouth of Kintzele Ditch. At that point the bearing of a vector perpendicular to the local shoreline is 337deg, giving a bearing along the beach of 63 deg, looking towards Mt. Baldy. With respect to this orientation, consider the figure fragment to the left. In the figure current vectors pointing straight upward represent currents flowing parallel to the Lake Michigan shoreline towards Mt. Baldy. Currents pointing straight downward represent beach-parallel currents flowing towards Central Avenue Beach. (Other directions have on or offshore components as well. Omit sentence.)Another important consideration is the time for a plume front to travel the distance between the mouths of the creeks and the measurement sites. As noted above, the distances from Central Avenue to Kintzele Ditch and Trail Creek are 0.6 and 3.9km respectively; the distances from Mount Baldy to Kintzele Ditch and Trail Creek are 1.0 and 2.4km respectively. As relative measures, the lake current velocities necessary to transport the fronts in one hour would be about 0.16, 0.28, 0.66, and 1.08m/s for the least to greatest distances respectively, assuming the currents are appropriately in the right direction. For two hours they would be about 0.08, 0.14, 0.33, and 0.54m/s, and so forth. Thus lag times would vary depending on the near-shore lake velocities. The measured currents are typically less than 0.5m/s but are sometimes in excess of 0.1ms during high concentration episodes. Thus, in the absence of substantial plume momentum, minimum times of travel for Central Avenue is on the order of one hour but, for all beaches, is typically more than two to ten hours.These lag times would tend to be decreased by the flow in the creeks themselves as the outflow jet momentum increases with flow. This momentum is partially preserved in the plumes as they bend in the direction of the lake current, actually able to reduce the lag time to the measurement site. In any case, Central Avenue could be affected by Kintzele Ditch effluent within one or two hours even in weak current scenarios.

Prototype Central Ave. Episode

Day 187 episodeBacteria > 100 (log 2)

antecedentupcoast flow

followed bydowncoast flow

antecedentrainfall

The Mechanics of a bacteria episode at Central Avenue beachIn the hours or days preceding an episode the antecedent flow is upcoast bending the Kintzele Ditch plume eastnortheastward towards Mt. Baldy. During this time, in the absence of a proximate source to the southwest of Central Avenue Beach, beach water quality improves as relatively clean lake water sweeps over it. When the currents reverse, as they do early on Day 187, the Kintzele Ditch plume is bent in the opposite direction and the plume front moves towards Central Avenue Beach. When the plume front arrives the bacteria concentration rises significantly as an episode occurs. If there is antecedent rainfall, as there is in this case, storm runoff is expected to greatly increase the source strength Kintzele Ditch. Minor local sources, perhaps the beach itself, cause some increase on Day 186 even before the plume front arrives.This pattern is observed to a lesser or greater extent on days 184, 187, 192, 196, 199, 205, 209, and 217. (It should be noted that the current vectors are plotted at the end of their averaging period on the time axis, so that some leftward shift of the vectors would be appropriate. This statement needs to be verified).This physical interpretation of events is supported by Figure ? that shows the variation of the correlation between current component and beach concentration as the projection of the current vector changes due to rotation of the coordinate system. The maximum negative correlation of 0.7 at about 65 degrees shows that the main bacteria source is in the direction of Kintzele Ditch. A component parallel to the beach would imply a rotation of only 23deg. Thus, it appears that a small shoreward component also helps to improve the correlation. This is consistent with a Kintzele Ditch plume that is bent towards Central Avenue beach but is prevented from entering the deep lake by a shoreward component.

Central Avenue Correlations

Rotation statistics for Central Avenue beach. Similar figures will be available for Mount Baldy.

Mount Baldy Episodes

Day 217 episodeTrail Creek source

Antecedentupcoast flow

followed bydowncoast flow

antecedentrainfall

The mechanics of two different bacteria episodes at Mount Baldy beachUnlike Central Avenue beach, where both the Kintzele Ditch and Trail Creek sources are upcoast, Mount Baldy beach is situated between the two main nearby sources. Consequently, it should not be surprising that bacteria episodes can occur anytime a persistent alongshore current pattern is followed by a current reversal. Figure ?a shows an episode when Trail Creek is the source of elevated bacteria concentrations. Antecedent rainfall and antecedent upcoast flow is followed by a current reversal and the apparent arrival of the Trail Creek plume front on Day 217. Figure ?b shows an episode when Kintzele Ditch is the source of elevated bacteria concentrations. Antecedent rainfall and antecedent downcoast flow is followed by a current reversal, upcoast flow, and the apparent arrival of the Kintzele Ditch plume front on Day 213.Because current reversals in either direction can lead to a bacteria episode, the correlation coefficient of concentration to current component decreases significantly, to about 0.4 (Figure ??). The sign of the correlation coefficient reflects the fact that Trail Creek is the more important source of bacteria.

Day 213 episodeKintzele Ditch source

Antecedentdowncoast flow

followed byupcoast flow

antecedentrainfall

Day 204 episodeKintzele Ditch and Trail Creek sources

Antecedentupcoast flow

followed bydowncoast flow halfway through the episode

antecedentrainfall

Day 189 episodeKintzele Ditch source

Little or no antecedentrainfall

persistentupcoast flow

Mount Baldy Episodes (cont.)

Other episodic scenarios at Mount Baldy beachOther sequences of events are possible at Mount Baldy. In Figure ?a period of little or no rainfall before the episode coincides with persistent upcoast during most of the two-day episode. Thus Kintzele beach is the likely source of contamination. (Is it possible that Kintzele Ditch concentrations are still high two days after the last rain event or was there rainfall in the Kintzele Ditch watershed that was not represent by the Washington site?) With sources on both sides of Mount Baldy, a current shift is not required with upcoast flow to bring a plume front to the site.Figure ?b represents a situation in which the first day of the episode occurs with antecendent rainfall predominantly upcoast flow, followed the second day by downcoast flow. Thus, especially with rainfall persisting through the first day of the episode, it is likely that the main source of contamination during the first day of the episode is Kintzele Ditch and the second day Trail Creek.With components of opposite sign being associated with high concentrations, it is not surprising that the correlation between concentration and current component is much lower than for Central Avenue.

Prelude to 2006 Field Season

Prelude to 2006 Field Season

Prelude to 2006 Field Season

Modeling Trail Creek and Kintzele Ditch

Mantha S. Phanikumar1, Lubo Liu1, and Richard L. Whitman2

1Department of Civil & Environmental Engineering, Michigan State Universtiy, East Lansing, MI 48824

2Lake Michigan Ecological Research Station, U.S. Geological Survey, Porter, IN

0.00 0.50 1.00 1.50 2.00 2.50 3.00Log E. coli

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Pre

dic

ted

Val

ue

R Sq Linear = 0.4260.50 1.00 1.50 2.00 2.50 3.00

Log E. coli

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Pre

dic

ted

Val

ue

R Sq Linear = 0.723

Central Avenue, all winds

Mount Baldy, all winds

Parameters used:Kintzele Ditch conductivityWave height

Parameters used:Kintzele Ditch conductivityWave heightBarometric pressureWave period

log E. coli =1.408-0.262(baropress)-0.179(KDspcond)+0.364(waveht)-0.153(wvperiod) + error

log E. coli = 1.286 -0.132 (KDspcond)+0.336 (waveht)+error

Modeling of Two Eastern Indiana Dunes Beaches

Zhaoqing YangBattelle, Seattle, Washington

CRADA etc. Collaborators

Ecosystems Research Division

Athens, Georgia, 8 March 2006

Tarang KhangaonkarBattelle, Seattle, Washington

Anne SigleoEPA, Newport, Oregon

Comparing models

Postulate:It is beneficial to have access to a variety of models.

Southwest Michigan

Yaquina River NOAA map

Slide ?

…

PDS velocity contouring output. Tarang, could you model this scenario?

Output of the steady-state PDS model

Slide ?

…

The ambient current is about 0.2m/s used in the following PDS run.

FVCOM model run, near maximum ebb

PDS run, two concentration similarity profiles

In this run the effluent and ambient concentrations are set to 0.81 and 0.2 respectively, numerically equal to the corresponding effluent and ambient velocities. Green corresponds to one similarity assumption (probably the 3/2 power profile), red to another (experimental one). (I won’t know the profile until I get my Delphi compiler going again, or I will do my best checking the code with an ASCII text editor.) As should be apparent from the following, I think the concentration isopleths represent the isotachs well.In the model superpositions, following, note that the PDS aspect ratio may not be perfect. Presumably the FVCOM graphics aspect ratio is 1:1.

Slide ?

This panel superimposes FVCOM and PDS simulations. The input conditions for PDS assume a uniform, steady-state ambient current of 0.2m/s flowing southward. The coastline is assumed to be linear and the water depth is assumed to be deeper than the penetration of the surface plume into the water column. The river effluent is assumed to have a velocity at the mouth of the jetties of 0.81m/s, corresponding to a flow of about 2000m3/s.

FVCOM vs PDS chi

The PDS simulation is shown in red. The input conditions are chosen to closely correspond to the FVCOM simulation shown in blue. The innermost isotach corresponds to 0.6m/s, decreasing by intervals of 0.05m/s: 0.6, 0.55, 0.5, and 0.45m/s respectively. In this case the isotachs are based on isopleths of concentration. This approach is justified because, in a model such as UM3, another Visual Plumes plume, concentration and lineal momentum share the same basic mixing equation. While in this case the plume momentum is obviously two-dimensional, the trajectory is sufficiently straight for the assumption to be useful. The plume is assumed to have a concentration value numerically equal to the velocity at the source, and the background concentration the same value as the ambient current speed.

This approach is adopted because it more nearly places the two solutions in agreement. In other words, PDS handles momentum conservation in a way that would indicate an even longer plume at the given isopleth values.

The disagreement between the two solutions gives this approach more weight. The PDS solution indicates that the 0.5m/s isotach based on the more conservative estimate extends 3.75km southward from the jetties. At this distance the FVCOM indicates that the plume velocity has decayed to a value of about 0.25m/sec, much closer to the ambient velocity of about 0.2m/sec than the PDS solution would indicate.

It is apparent that the dispersion implied by the FVCOM solution is much greater than the dispersion implied by the entrainment assumption used in the PDS model. The FVCOM plume rapidly loses its identity, whereas PDS maintains it to much greater distances. Previous runs with PDS in weaker currents show that it gives reasonable estimates of concentration and current measurements. This suggests that smaller dispersion coefficients in FVCOM or smaller grid elements, or both, would help to better estimate plume behavior….

Comparing velocity and concentration profiles

Scalar profile Velocity profile

These contour isopleths result from the same input conditions. In (a) the a conservative tracer concentration is contoured; in (b) the velocity distribution is contoured (isotachs). The velocities are much more persistent than the concentrations, indicating that PDS treats momentum mixing differently than dispersive tracer mixing. The former appears unrealistically persistent, the plumes becoming very long. This difference is not as pronounced under very low current conditions (a subject for another slide).The next slide shows the velocity profile solution superimposed on the FVCOM flow pattern.

Slide ?

This is the PDS velocity simulation. Notice that the innermost 0.6m/s isotach is longer than the 0.5m/s isotach based on the concentration mixing equation estimate used in the previous figure.

FVCOM vs PDS chi