Investigating relationship of nephelometric turbidity unit and total suspended solids with the inherent optical properties parameters derived from spectra reflectance

摘要

In this project, the relationships between the turbidity of water measured by its total suspended solids (TSS), Nephelometric Turbidity Units (NTU) and the inherent optical properties computed from the spectral reflectance using the bio-optical model were investigated. It is hope that the results obtained could allow one to compute the water turbidity without needing to physically visit the site and take measurements. This could be extended to estimating the turbidity from remote sensing satellite imagery. Control experiments were initially carried out with a 1m deep by 0.5m × 0.5m tank. The tank was first filled with clean water. Various types of common soil (e.g. burnt soil, riverbed and silt) were then added progressively and the TSS, NTU and reflectance measured. The different types of soils were used to study the variability of the relationships across different soil types. The experiment results were very encouraging. Linear relationships between NTU and TSS, backscattering coefficient and TSS, backscattering coefficient and NTU were obtain. More interesting, the relationship between backscattering coefficient and NTU is independent of soil type. Field verification measurements were also conducted to confirm the findings of the lab experiments.