Vegetation dynamic in the water level fluctuating zone of Three Gorges reservoir area during 2015-2018 using GF-2

Abstract

In Three Gorges reservoir area, vegetation of the water level fluctuating zone (WLFZ) plays a key role in the ecological functions. This study develops a spatiotemporal dynamic analysis method for vegetation of WLFZ using Very High Resolution satellite imagery to monitor the characteristic of vegetation recovery in WLFZ of Three Gorges reservoir area in recent years. Five epochs of GF-2 satellite imagery acquired between 2015 and 2018 were analyzed. Multi-temporal vegetation classification maps against meteorological and hydrological data suggested that vegetation coverage of the WLFZ in the whole study area was not increasing over years (it was increased by 19.3% from 2015 to 2017, but decreased by 29.86% from 2017 to 2018.), but was closely related to the hydrology and meteorology of that year. By the spatial overlapping of multi-temporal vegetation classification maps, three and four years of vegetation no-change maps were obtained for spatiotemporal analysis. It was found that there were two kinds of vegetation recovery coexisting in the WLFZ of Three Gorges reservoir area, one shows stability in time and space, account for 32.27% of the WLFZ in the whole study area; another has great uncertainty and was vulnerable to the hydrology and meteorology factors.