The impact of bottom brightness on spectral reflectance of suspended sediments

Two experiments were conducted outdoors to investigate how bottom brightnes s impacts the spectral response of a water column under varied suspended se diment concentrations. A white aluminum panel placed at the bottom of the t ank was used as the bright bottom, and a flat-black tank liner served as th e dark bottom. Sixteen levels of suspended sediment from 25 to 400 mg litre (-1) were used in each experiment. Spectral data were collected using a Spe ctron SE-590 spectroradiometer. The major findings include the following: t he bright bottom had the greatest impact at visible wavelengths; when suspe nded sediment concentrations exceeded 100 mg litre(-1), the bright bottom r esponse was found to be negligible; and, substrate brightness has minimal i mpact between 740 and 900 nm, suggesting that these wavelengths are best fo r measuring suspended sediment concentrations by means of remote sensing.