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).