Study on the Fluvial Landscape Patterns of Upper Jingjiang Segment, Yangtze River, Using Multi-temporal Remote-Sensing Imageries

摘要

The apparently spatial-temporal dynamics of fluvial landscape ecology make multi-temporal data critical for study in river corridor. As a geomorphologic ally active segment in the middle reach of Yangtze River, China, Jingjiang segment provides important ecologic functions for Yangtze River. Taking upper Jingjiang segment as an example and using Landsat ETM+ imageries respectively acquired in the high-water and low-flow periods of 2002, we aims to understand the usefulness of multi-temporal remote-sensing data for the study of fluvial landscape in middle reach of large alluvial river. Four types of first-level landscape and 10 subtypes of second-level landscape are extracted from imageries. Scale effect of the fluvial landscape of upper Jingjiang segment is addressed. Surface-connected channel forms the matrix of upper Jingjiang segment in all hydrologic periods. Isolated patches of river islands, which are large in size and long in edge length and have high contiguity, may have critical importance for the fluvial landscape of upper Jingjiang segment. Patches of channel bars are relatively small in size but abundant in number and have high connectance. Pool patches, which are small in size, abundant in number and irregular in shape, may be of particular importance for the fluvial landscape in low-flow period. Large changes of the landscape of upper Jingjiang segment within a hydrologic period are also clearly presented and reflect the effect of hydrological disturbance. Patches in low-flow period are smaller in size, more in number, longer in edge length and more irregular in shape than that in high-water period. The contagion, diversity and evenness of patches apparently increase in low-flow period.