Dynamic evolution of vegetation and drainages in the Jiuzhaigou valley scenic area before and after the "8 August 2017" earthquake under conditions of travertine habitat conservation and restoration

The restoration of the original habitat after an earthquake is very important for rapid reconstruction of territorial vegetation and the restoration of the drainage area. In this study，the dynamic changes of vegetation coverage，soil moisture，forest area and river system area of the Jiuzhaigou valley core travertine scenic spot and the whole scenic spot before and after the 2017 earthquake and after the travertine habitat conservation and restoration were evaluated by using Landsat-8，and Gaofen 1#，2# satellite images. The results show that the coverage area of high，medium and low vegetations at the travertine core scenic spot and the whole scenic spot has increased significantly after the travertine conservation and restoration with artificial as auxiliary and natural as the main. The ecological types of bare land still exist，but show a decreasing trend year by year. In addition，the types of medium vegetation cover also decreased compared with those after and before the earthquake. In the second year after conservation，wet and very humid areas， total forest area and river system area increased significantly compared with before and after the earthquake. Overall，there is a positive correlation among high vegetation coverage area，forest area and river area. This may be due to the rapid restoration of original habitat under human intervention，which increased vegetation coverage area，and enhanced the roles of vegetation evapotranspiration and interception，and further affected the hydrological process of the watershed and promoted the restoration of the drainage area.