Study on impacts of stormwater runoff from road and wood-pavement in Jiuzhaigou Valley
九寨沟公路和栈道降雨径流污染负荷过程的研究

The design,execution and interpretation of results from novel rainfall simulation experiments conducted on highroad and wood-pavement in Jiuzhaigou Valley in 2005 are described.These experiments employed adoption of indigenous method rainfall simulation technology to deliver controlled probability of occurrence of 60%,thirty-minute rainfall events to six predefined road and wood-pavement areas.The temporal evolution of total phosphorus loads from each road and wood-pavement surface was also measured downstream of the simulations at three-minute intervals.These experiments provide the first quantitative assessment of the pollutant export characteristics of roads and wood-pavements under representative and quantifiable rainfall conditions.In particular,the study showed road and wood-pavement runoff to be characterized by: a pollutant concentration first flush lasting approximately 3 minutes;and an approximately constant mass loading rate for a set rainfall intensity.It also showed that the majority of pollutant loads from roads and wood-pavements are exported from frequent small rainfall events,as compared to infrequent larger rainfall events.The results are used to provide a reason for constructing the load model of road and wood-pavement that makes use of event mean load instead of event mean concentration adopted by former researchers.