黄河三角洲潮滩潮沟近期变化遥感监测

Change Detection of Tidal Flats and Tidal Creeks in the Yellow River Delta Using Landsat TM/ETM+ Images

作者选用1986年和2001年两个时相的Landsat TM/ETM+影像,结合遥感、地理信息系统(GIS)和分形理论研究了黄河三角洲典型河口岸段潮滩潮沟的发育演变.结果表明:近15年来,挑河口～106站和现行水河口(1976～1996年黄河入海口,下同)～甜水沟岸段分维值D增大,呈顺向演替;其余岸段分维值均减小,表现为逆向演替.人工围垦挤占了大面积潮滩,人工岸线不断向海扩展,其最大推进速率达0.8 km/yr;同时,潮沟长度缩短,最严重的岸段每年减少14.9 km.通过分析表明,人类活动已成为影响三角洲潮滩发育的重要因子,其导致整个三角洲的潮滩体系严重退化,自然形成的潮沟时空谱系不复存在;另外,发育时间长短、入海泥沙、海浪和潮流对潮滩发育演变亦非常重要.目前,黄河三角洲潮滩可分为河口滩、潮控滩、浪控滩和人控滩4大类型.

We have interpreted tidal flats and tidal creeks in 5 typical tidal basins around the Yellow River Delta using Landsat TM/ETM+ images acquired in June 1986 and August 2001. The drainage density and fractal dimension of tidal creeks of each tidal basin were calculated. The results show that a lot of changes have taken place during the past 15 years in tidal zones of the Yellow River Delta. The average change rate of tidal creeks' length in 5 typical tidal basins is -14.9 km/yr, -8.4 km/yr, 2.5 km/yr, 4.7 km/yr and -4.9 km/yr respectively (1986-2001). In the Taoer River Estuary, artificial coastline has advanced rapidly towards the sea (0.8 km/yr) due to the development of oil fields, fishponds and salt ponds. Box-counting dimensions of tidal creeks and coastlines have decreased, which showed that the tidal flats and tidal creeks systems in the study areas are retrogressive except the tidal basins from south of the Yellow River mouth to the Tianshuigou River Estuary and from Tiaohe River Estuary to 106 Station.