Abstract
Abstract. There are frequent sand digging and heaping activities in shoal in the Pearl River Estuary (PRE). Water depth has changed in patches, which can be imaged by synthetic aperture radar (SAR). According to SAR imaging mechanism of underwater bathymetry, a 3-D hydrodynamic model is used to demonstrate the temporal variations of the shoal topography changes due to sand digging and heaping. A microwave radar imaging of oceanic surface’s program is used to simulate the variation of normalized radar cross section (NRCS) induced by the ocean surface current. The simulation is carried out to study the digging-heaping shape, water depth changes on SAR imaging of shoal bathymetry. Results indicate several points as followings. 1. Circle-shaped sand digging and heaping are imaged clearer by SAR than other shapes. 2. Sand heaping has a greater effect on SAR imaging than sand digging. 3. Bigger depth change induces bigger NRCS variation.
Highlights
Since the 1980s, with the economic booming in China, there has been great demand of sand for the infrastructure
The light streak appears in the left of the sand heaping area, while the dark streak appears in the right, which is contrary to the case of the sand digging
(1) Circle-shaped sand digging and heaping are imaged clearer by synthetic aperture radar (SAR) than other shapes
Summary
Since the 1980s, with the economic booming in China, there has been great demand of sand for the infrastructure. A large amount of sand is being minded across most rivers in China regions with the largest scale of such activity in the middle and lower reaches of the Yangtze River, the Pearl River Delta, and the adjacent estuarine areas (Jia et al, 2007). The deterioration of ecological environment in these estuarine areas has something to do with the frequent sand excavation activities (Liu et al, 2006). With the rapid population growth and economic development, the Pearl River Delta is the area with the highest urbanization development level. There are plenty of sand resources in channels and shoals in the PRE, which can supply raw materials for construction. There are two kinds of large-scale dredging activities, one is reclamation for construction, and the other is channel dredging (Liu et al, 2005)
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