Water Quality Management - River Dynamics and Integrated River Management - page 563

Fig. 9.4 Reaeration-rate coefficients measured and estimated with equations developed from multiple linear regression
for pool and riffle streams in the USGS database (after Melching and Flores, 1999)
Fig. 9.5 Reaeration-rate coefficients measured and estimated with equations developed from multiple linear regression
for channel control streams in the USGS database (after Melching and Flores, 1999)
conditions, the mean stream width and depth adequately describe stream scale, whereas for pool and
riffle conditions, the mean stream width and depth are difficult to determine and, thus, discharge serves
as a surrogate for stream scale.
For equation verification, a data set of K a measurements made with tracer-gas procedures by other
agencies was compiled from the literature. This compilation included 127 reaches on at least 24 rivers in
at least 7 states. The streamflow regime was identified as pool and riffle for only about 30 reaches in the
verification database, and for the other reaches streamflow regime was unspecified. Because the flow
regime is unknown for most reaches, the best estimate of K a from Eq. (9.14) or (9.16) and Eq. (9.15) or
(9.17) was used for the unspecified reaches in the overall verification statistics in Table 9.3 and in the