Remote Sensing of Suspended Sediments in Surface Waters, Using Modis Images

Collecting information about (Suspended Sediment Concentration) SSC, in coastal Waters and estuaries is vital for proper management of coastal environments. Traditionally, SSC used to be measured by time consuming and costly point measurements. This Method allows you to accurately measure SSC only for a point in space and time. Remote sensing from air-borne and space-borne sensors have proved to be a useful method to such studies as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. The reason for success of remote sensing in such surveys is the strong positive relationship that exists between SSC and remotely sensed spectral radiance Lλ . This Spectral radiance could be in the sun reflected and/or scattered or thermal terrestrial wavelength bands. Many workers have shown that the relationship between SSC and Lλ  strongly depends on the intervening atmospheric constituents as well as the suspended material and depth. To find an algorithm relating SSC to Lλ  over Bahmansheer River Estuary at the North-West of Persian Gulf, a three-month field measurement (April to June 2003) were conducted while we had MODIS sensor on board of Orbview-3 over-passed the scene simultaneously. Ninety samples in fifteen trips were collected. Also the environmental parameters such as atmospheric visibility, air and water temperature, current direction and speed of water at the sampling point, wind speed and humidity were measured simultaneously. The collected samples were analyzed thoroughly by measuring density, diameters of the sediment particles and determining the sediment constituents. Total density were ranging between 30 to 500 (mg/lit), the range of particle diameter were from less than a micrometer to more than 20 micrometers and finally it was found that the sediment were composed of Quartz, Kaolinite, Orthoclase, Chlorite, Calcite, Gypsum, Muscovite, Halite, Anhydrite, Apatite, Biotite, and low amount of Albite. It is found that the spectral characteristics of these compositions are partly responsible for the reflected and/or scattered energy in different bands while the correlation between larger suspended particle density and Lλ were profound. Also the effects of environmental parameters on the results were discussed. It is believed that the atmospheric aerosols are the main reason for the poorness of the correlation coefficients.