THE POTENTIAL FOR REMOTE SENSING OF LOESS SOILS SUSPENDED IN SURFACE WATERS¹

Abstract

The potential for detecting the concentration and type of soils suspended in surface water through remote sensing techniques was investigated by studying the spectral reflectance of two types of soils in suspension. In a large tank filled with 7510 liters of water, 20 levels of suspended sediment (soil) concentration (SSC), ranging from 50 to 1000 mg/l were prepared. A high resolution spectroradiometer was used to measure the reflectance at each SSC level. The reflectance spectra of two contrasting soils were distinct in the visible and near infrared (NIR) portions of the electromagnetic spectrum. The wavelength range between 580–690 nm (visible) was found to be optimal for indicating the type of soil, whereas, the wavelength range between 714–880 (NIR) was found to be appropriate for estimating the concentration of sediment suspended in surface waters.

Application of spectral decomposition algorithm for mapping water quality in a turbid lake (Lake Kasumigaura, Japan) from Landsat TM data

“…Significant peaks were observed at 420 nm for clear water, 645 nm for NPSS, and 575 nm and 700 nm for phytoplankton. Similar spectral features were found in previous studies (Lodhi et al, 1997;Gitelson et al, 1999;Kobayashi et al, 2000).…”

A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

“…High concentrations of SPM lead to detectable water leaving reXectances and absorption in the near infrared, so that atmospheric correction methods for satellite data based on (near) infrared bands cannot be applied. High SPM concentrations might saturate the spectrum (as shown in the reXectance spectra presented by Lodhi et al 1997), while the similarity in absorption properties by SPM and CDOM, and to a minor extent by Chl-a (in the blue wavelengths: 400-500 nm), complicates the separation of individual components. A positive side eVect of the extremely high concentrations is that, even in these shallow waters, bottom inXuence is greatly reduced due to the high attenuation of light.…”

Contribution of Raman Scattering in Remote Sensing Retrieval of Suspended Sediment Concentration by Empirical Modeling

“…A comparison of Raman contribution at two peculiar stations (least cloudy) has been considered (Table I). According to Lodhi et al [43], the reflectance from suspended sediments (clay and silt) is greatest near 670 nm. The changes near blue end (443.7 nm) of EM spectrum can be considered as absorption dominated and changes near the red end (671.6 nm) of spectrum as scattering dominated [44].…”