3.2. Sediment Transport during Hurricane Harvey
Sediment transport during Hurricane Harvey was mainly affected by the
significant amount of silt carried by the floodwater from the highly
erodible silt-rich soil behind Addicks Reservoir (flood control dam) and
upstream of Greens Bayou (see Figure 1). TSS and flow data historically
collected indicated that during the low to moderate flow regimes, there
were significant correlations (P-value < 0.05) between TSS
concentrations and flow rates (at the time of sampling as) as shown in
Figure S4 in the SI. During Hurricane Harvey, with the historical high
flow rates, the measured TSS concentrations were higher than the median
historical levels (see Figure 3 as an example). Using the median TSS
values for each bayou multiplied by the daily flow rates from 1995 to
2020, Figure 4 shows the potential sediment daily load to the HSC-GB for
each bayou. It should be noted that this figure does not show the
outliers (mainly extreme events), and also, does not include all
bayous/rivers discharging into the HSC-GB system due to the absence of
flow gage or water quality monitoring stations in some of the
tributaries. Even without the outliers, a load as high as 7,000 tons/day
could have been discharged into the GBES just through the San Jacinto
River (SJR).