Charles River E. coli (Lagrangian)

The processes affecting the fate and transport of Escherichia coli in surface waters were investigated using high-resolution observation and modeling. The concentration patterns in Boston's Charles River were observed during four sampling events with a total of 757 samples, including two spatial surveys with two along-river (1,500 m length) and three across-river (600 m length) transects at approximately 25-m intervals, and two temporal surveys at a fixed location (Community Boating) over seven days at hourly intervals. The data reveal significant spatial and temporal structure at scales not resolved by typical monitoring programs. A mechanistic, time-variable, three-dimensional coupled hydrodynamic and water quality model was developed using the ECOMSED and RCA modeling frameworks. The computational grid consists of 3,066 grid cells with average length dimension of 25 m. Forcing functions include upstream and downstream boundary conditions, Stony Brook, and Muddy River (major tributaries) combined sewer overflow (CSO) and non-CSO discharge and wind. The model generally reproduces the observed spatial and temporal patterns. This includes the presence and absence of a plume in the study area under similar loading, but different hydrodynamic conditions caused by operation of the New Charles River Dam (downstream) and wind. The model also correctly predicts an episode of high concentrations at the time-series station following seven days of no rainfall. The model has an overall root mean square error (RMSE) of 250 CFU/100 ml and an error rate (above or below the USEPA-recommended single sample criteria value of 235 CFU/100 ml) of 9.4%. At the time series station, the model has an RMSE of 370 CFU/100 ml and an error rate of 15%.

Hellweger, F. L., Masopust, P. 2008. Investigating the fate and transport of E. coli in the Charles River, Boston using high-resolution observation and modeling. J. Am. Wat. Res. Assoc., 44(2):509-522.

Note: The animation is from a slightly earlier version of the model than the final one presented in the paper.

Category:

Science & Technology

Tags:

• Charles River
• Bacteria