Comparison of measured suspended sediment concentrations with suspended sediment concentrations estimated from Landsat MSS data

Abstract

Abstract Landsat multispectral scanner (MSS) data for 27 dates between January 1983 and June 1985 for Moon Lake in Coahoma County, Mississippi, were analysed to determine if Landsat MSS digital data could be used to estimate suspended sediment concentrations in the surface waters of a small agricultural lake. Field measurements of suspended sediment concentration in the surface water and other water quality variables were available for five locations in Moon Lake within 0 to 13 days of each of the 27 Landsat overpass dates. Pixel values, radiance and reflectance measurements from Landsat MSS data from 14 scenes were compared with field data and used to develop simple and multiple regression equations to estimate suspended sediment concentration in the surface water of the lake. The best equations were used to estimate the suspended sediment concentrations for the 13 other Landsat scenes. The coefficient of determination for the relationship between measured and estimated suspended sediment concentrations was greater than 0·80 and the root mean square error was less than 40 mg l−1 when equations using either the radiance and reflectance data were used to estimate suspended sediment concentrations. This study shows that good estimates of suspended sediment concentrations can be made using Landsat MSS data especially in the range of concentrations between 50 and 250mg l−1 which are the critical concentrations for assessing conservation needs. Suspended sediment concentrations greater than 250mg l−1 were underestimated by most of the equations indicating a saturation of reflected solar radiation at higher suspended sediment concentrations. Thus a technique using Landsat MSS digital data can be developed to monitor the landscape to locate those reservoirs with critical suspended sediment concentrations quickly. Soil and water conservation efforts can then be concentrated on the watershed of those reservoirs where suspended sediment is greatest.