An enhanced MODIS remote sensing model for detecting rainfall effects on sediment plume in the coastal waters of Apalachicola Bay

Mapping of total suspended solids (TSS) was conducted to investigate rainstorm-induced characteristic of sediment plume in the coastal waters of Apalachicola Bay. An improved TSS quadratic polynomial regression model (Calibration: R2=0.8586, N=32; validation: RMSE of 4.76 mg/l, N=30) for MODIS remote sensing was presented in this study. TSS mapping of MODIS before and after a rainstorm event showed distinct temporal-spatial variability of TSS concentration. Driven by ocean tidal current, a storm plume of width at about 40-50 km was formed flowing towards southwest of study area. The distinct boundary separating the highly turbid (west side) and relatively clear water (east side) was found near Sikes Cut. Further, by taking the TSS mapping under the low river discharge condition due to a local rainstorm as a reference of background TSS, two thresholds of TSS (25 and 45 mg/l respectively) were used to estimate the range of rainstorm plume and the central area of sediment load from surrounding land, and the spatial extent and evolution of the sediment plume during the local rainstorm. Besides, it was found that the storm plume concentration of TSS at east side of Sites Cut was quickly diluted under 25 mg/L, forming a storm plume towards east with width at about 7-8 km. The method developed in this study may be used to support coastal storm water research and management activities.