Characteristics of Landscape Change Patterns at Three Distinct Stages of the Construction and Operation of the Three Gorges Reservoir From 1986 to 2017

Abstract

Analyses of landscape change patterns that are based on elevation and slope can not only provide reasonable interpretations of landscape patterns but can also help to reveal evolutionary laws. As a complex geographical unit, the ecosystem environment in the middle reach of the Yangtze River has experienced great changes due to the construction of the Three Gorges Reservoir (TGR) and its associated human activities. Here, based mainly on a digital elevation model (DEM) and remotely sensed images from 1986, 2000, 2010, and 2017 and by using GIS technology, buffer analysis, landscape element change and landscape pattern indices, the spatial and temporal evolution characteristics of different elevations, slopes, and buffer landscape types were analyzed in a typical watershed, as well as an evolutionary model of the landscape pattern. The results indicated that (1) the landscape elements along the land classification and buffer zone that were influenced by the TGR construction have undergone a phased change, with the period 2000-2010 being the most dramatic period of landscape evolution during the impoundment period; (2) landscape type shifts from human-dominated farmland to nature-driven forestland and shrub-land as elevations, slopes and buffer distances increased. The landscape has shifted from diversity to relative homogeneity. (3) land types and buffer zones have exhibited a significant effect on the landscape pattern index, which is reflected in the differences in landscape type indices for spatial extension and temporal characteristics. The results of this study illustrate the pronounced effect of the TGR on landscape patterns, and these findings will elucidate the scientific basis and provide a reference for sustainable land resource management in the study region.