Observation of Suspended Sediment in the Surrounding Sea Waters of Dajin Island Based on CASI Hyperspectral Data

Abstract

In recent years, with the rapid development of regional economy in the Pearl River Estuary, drastic change in the content and transport patterns of suspended sediment in water bodies, which mainly caused by variations in land use patterns and bank erosion, imposed a profound impact on the development and evolution of the estuary Delta as well as the coastal ecological environment. In this study, we used the measured spectral data to establish inversion algorithm and to inverse suspended sediment based on CASI hyperspectral data, the accuracy of the inversed CASI and MODIS suspended sediment were verified with in-situ measured data. The results show that: 1) Single-band exponential model (SSC=4.5e21.922*Rs(622.486)) can well retrieve the suspended sediment concentration in the experimental sea area, and the average relative error is approximately 11.15%; 2) The suspended sediment content lies between 0.45-12.15 mg/L over the study area, and the main input source is land-based input from the west coast of Huangmao Sea, the ecological impact on the dolphin reserve can be neglected; 3) Combined with MODIS-based remote sensing images of suspended sediment in the Pearl River Estuary, it is found that there is an obvious branching phenomena when the sediment is transported from the Huangmao Sea to the outside of the mouth. The main axis of runoff is transported along the northeast direction of Dajin Island to the southeast direction of Dajin Island in the estuary area, while the coastal current is transported along the northeast direction of Dajin Island to the southwest direction of Dajin Island. As a result, there are low suspended sediment and high transparency sea areas in the north of Dajin Island, which are suitable for aquaculture.