Abstract: With the development of the remote sensing, it became more and more important in environmental monitoring. Especially in water quality remote sensing and environment background mapping, there has been a lot of work to be done. But water quality is relative to the environment and human’s activities. The suspended sediment is one of the most important aspect of the water quality, so in this paper, some work about environmental background mapping and its relationship to the suspended sediment in Jilong River, Taiwan, is done. First, according to the suspended sediment concentration measured in field and the standard provided by Environment Office of Taiwan, the river suspended sediment concentration is divided into four levels. The grades of all the river are acquired by use of maximum likelihood classification of SPOT band 1 and 2. Then, the environmental background is acquired by supervised classification with TM and SPOT images based on the landuse map and other statistical information. The predominant background is forest, about 41% of the total area. The suspended sediment map and the environmental background map of Jilong River show that the suspended sediment concentration is lower in upper reaches of the river where the land is mainly forest, while it is higher in lower reaches of the river where the river flow through the city. By calculate the proportion of the length of every grade of water bordering upon every kind of environment background, we find that the suspended sediment concentration is related to the land cover and city pollution. The source of the suspended sediment is mainly the polluted warter poured from the city.

Key words: Environmental background, Jilong River, Suspended sediment, Water quality remote sensing