黄河三角洲侵蚀性岸段水下岸坡地质灾害及其空间分布

Geological hazards and their spatial distribution in the subaqueous slope at the erosive coast of the Yellow River delta

黄河的高含沙量和尾闾的频繁摆动，形成了独具特色的黄河三角洲。利用精密的测深仪，高分辨率的浅地层剖面仪和侧扫声纳等设备同步扫测所获取的记录，研究了黄河三角洲侵蚀性岸段水下岸坡的地质灾害及其空间分布特征。探测研究表明，研究区发育的地质灾害主要有冲蚀构造、凹坑与洼地、海底滑坡、海底刺穿、不均匀地层（切蚀-填充构造、声学透明层）、埋藏冲沟和古河道。地质灾害在空间分布上呈现平行岸线的带状分布，按水深可划分为3个区域。6m水深以浅区域，主要发育冲蚀构造，且冲沟、边缘陡坎和蚀余构造相间分布。6~14 m水深区域，主要发育凹坑与洼地、海底滑坡、海底刺穿和分布广泛的声学透明层。14 m水深以外区域，主要发育埋藏冲沟和古河道，其形成主要与海平面上升有关。

High sediment-laden water of the Yellow River and frequent migrations of the river course have formed a dis-tinctive Yellow River delta system. Based on the synchronous monitoring data obtained from the precise fathometer, high-resolution sub-bottom profiler and side-scan sonar, geological hazards and their spatial distribution in the subaqueous slope at the erosive coast of the Yellow River delta have been studied. Results showed that various geological hazards were found in the study area, including erosion structure, seabed pit and depression, submarine landslide, submarine diapir, uneven strata （cutting-filling structure and acoustic transparent layer）, buried gully and ancient riverway. Spatial distribution of these geological hazards could be generally divided into three belts parallel to the coastline with water depth changes. In area shallower than 6 m, erosion structure was a typical geological hazard, and the gully, erosion scarp and erosion residue appeared alternately. In the area with the water depth between 6 m and 14 m,the grouped seabed pits and depressions, the submarine landslide, the submarine diapir and the widespread acoustic transparent layers were distinctive geological haz-ards. In the area deeper than 14 m, the buried gully and the ancient riverway were found, which might be closely related to the sea level rise.