Using multi-temporal MODIS 250 m data to calibrate and validate a sediment transport model for environmental monitoring of coastal waters

Abstract

Abstract — Muti-temporal images of total suspended matter (TSM) derived from MODIS (Moderate Resolution Imaging Spectrometer) Terra 250 m red-band reflectance data were used to set the initial conditions and validate output of a hydrodynamic and sediment transport model ( ECOMSED) developed for Lake Pontchartrain, LA USA. During this initial study, the moderately high spatial resolution of the 250 m images provided a significant improvement in model definition when compared to model runs calibrated using 1 km data available from most ocean viewing instruments (e.g., AVHRR and SeaWiFS). The combination of daily MODIS imagery and model simulations offer a more robust monitoring and prediction system of suspended sediments than available from either system alone. The additional use of Aqua MODIS imagery should afford greater refinement in model paramerization and accuracy. Keywords-suspended sediments; sediment transport; MODIS; ECOMSED; water quality; monitoring. I. I NTRODUCTION Coastal waters, especially bays and estuaries, are often characterized by high concentrations of suspended materials derived from freshwater inflow and/or by the resuspension of bottom sediments. High concentrations of suspended sediments can govern many important water column parameters and processes including total water quality, benthic and phytoplankton productivity, and the redistribution and transport of water-borne pathogens, pollutants, and other materials. For example, several investigators [1, 2] have reported that the distribution and concentration of fecal coliform are directly associated with sediment resuspension and suspended sediment transport. These findings establish a direct link between sediment dynamics and public health. Hence, there is considerable interest in monitoring the transport and fate of suspended sediments from a broad range of investigators, environmental managers, and policy makers. Unfortunately, in many coastal aquatic systems, the use of traditional field measurements is inadequate to effectively monitor suspended sediments at the desired spatial and temporal scales due to the presence of dynamic physical processes (e.g., wind driven resuspension, river flow) or the large size of the system. In contrast, observations from remote sensing instruments and numerical models can provide unique information regarding the distribution and transport of suspended sediments that cannot be obtained using traditional field sampling techniques. Remote sensing from airborne and space-based instruments provide a large-scale synoptic view; numerical models provide a better understanding of the underlying system processes as 0-7803-9119-5/05/$20.00 (C) 2005 IEEE