关键词: 面源污染, 新安江上游, 土地覆被, 净化磷素量, 经济价值

Abstract: Urban park accessibility is an important index, which reflects the service level and the layout reasonability of urban parks. Using the network analysis and simple buffering methods from GIS technique, in combination with the data of roads and population, we evaluated the accessibility of urban parks within the 3rd Ring Road area in Shenyang City, Liaoning Province. The results show that the urban parks’ accessibility and quality of services are low within the 3rd Ring Road area of Shenyang. The accessible area measured by simple buffering is larger than that by network analysis, and their difference is nearly twice when the access time is within fifteen minutes. The accessibility of urban parks in the urban center area is much better than that of those parks in the suburb. The numerical relation of accessible area’s difference is related to the types of urban road network. In checkboard road network, the accessible area calculated using simple buffering is nearly three times larger than that by network analysis when the access time is within fifteen minutes, and the difference decreases gradually with the time increasing. This study can provide theoretical basis for optimizing green space structure.

Key words: nonpoint source pollution, upper Xin’an River, land cover,  , retained phosphorus, economic value.