Research The Suspended Sediment's Density And Distribution In Lake Chaohu Based On Remote Sensing

Suspended sediment is one of most important parameters for water quality. Its content directly influences water transparency, turbidness, optical quality (e.g., water color), the aquatic ecology ical condition and so on. Its content and the dynamic change also influence the local development of submarine landform and the fluctuation of the silt change greatly. Therefore the investigation of suspended sediment content is crucial to the water quality along the lake coastal zone, the landform, the ecology, the environmental research, as well as the coast project, the harbor construction and so on. The conventional investigation method is sampling, usually by ship, point by point. However, this method is slow and time-consuming and only a limited number of separated spot data in the time and spatial distribution can be obtained. In the meantime, the changeable complex of water's current situation in river-mouth and lakeshore area, and the changeable rate of suspended sediment make it very difficult for researchers to get an accurate understanding of the continuous and synchronized of the distribution and change of big area water bodies.The development of satellite remote sensing technology has dramatically changed the above situation. Satellite remote sensing has fast synchronization characteristic and can get the water phantoms in several seconds to several dozens seconds, sometimes even in shorter time span or instantly. These synchronization phantoms are extremely straightforward and useful for studying the movement and subsidence of the suspended sediments at the lake surface. With its instant synchronism, remote sensing technology can help us obtain area water's suspended sediment content data and its repetition data in short cycles. These data then can be used to monitor the suspension content, especially the distribution of silt content and its dynamic change, efficiently and effectively. In short, by overcoming the inefficiency of the conventional method, remote sensing technology has become extremely important to this kind of research. In the article ,we take Lake Chaohu as an example area and process its TM/ETM+ data in following steps:(1)we uses the relative atmosphere adjustment method to analyze the spectrum characteristic of this district's different rank density of sand waters. (2)we proposes an index method which does not need the suspended sediment information withdrawn from actual material (3) we proposes a model to identify the different suspended sediments density. (4)The classified result from this method is verified and analyzed by comparing with the actual material. (5)we analyzed the distribution and sources of the sediment. At last, we get the conclusions:1)After the process of TM/ETM+ data and analyze the spectrum characteristic of this district's different rank density of sand waters, we accurately withdrew the water body of the Lake Chaohu. Using the silt index method, we accurately identified the water's suspended sediment density information.2)Using the silt index method, we accurately identified the water's suspended sediment distribution, we found that the high suspended sediment sand are mainly located at the center of the western lake and the southeastern shore of the lake, the high suspended sediment has a close relationship with the silt. according to the remote sensing images, the high-density suspended sediment area has expanded 3 times during the past 13 years.3)We clearly distinguished the changeable region through the shade aberration value chart, The areas with suspended sediment density increases are mainly located in the north of the western lake, the hangpu and zhegao river mouth districts, the center of the lake and the south of the eastern lake;The areas with suspended sediment density reductions are mainly located in most of western lake and the place of huangshazhan and dongguan village ; the invariable are mainly located in some of eastern lake.4)the comprehensive survey shows that the main sources of suspended sediment of Lake Chaohu are river transportation and erosion of the lakeshore ; the concentration change of suspended sediment concentrion of water body was closely related with land use change in lake chaohu basin .