现代黄河三角洲地区地面沉降特征研究

IOCAS-IR > 海洋环流与波动重点实验室

	现代黄河三角洲地区地面沉降特征研究
其他题名	Study on the Characteristics of Land Subsidence in the Mordern Yellow (Huanghe) River Delta
	杜廷芹
学位类型	博士
	2009-05-27
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	现代黄河三角洲地面沉降 D-insar 固结沉降地壳垂直运动
摘要	针对目前现代黄河三角洲地区普遍存在的地面沉降问题，本文以整个现代黄河三角洲平原地区为研究对象，通过收集的重复性水准测量数据、遥感影像、渤海海底及三角洲平原沉积物物理力学数据、长期验潮站数据以及前人文献数据等资料，综合运用雷达差分干涉测量技术（D-InSAR）、工程地质学、GIS和随机动态分析方法，探讨了现代黄河三角洲地区近期地面沉降的现状，并对其自然因素影响下的形成与发展过程进行了综合分析，最后探讨了地面沉降对三角洲发育演化的环境地质效应。研究结果表明：现代黄河三角洲在以宁海为顶点的河口扇形区域，近期均经历了不同程度的地表下沉过程，但是随区域地理位置和时间的不同，地表变化空间差异性比较明显；三角洲顶点附近区域的下沉速率自上世纪末开始逐渐减小，后期甚至出现轻微的抬升；滨海沿岸附近地区的地表形变特征相对比较复杂，各期叶瓣相互叠置及其各类沉积物的不均匀分配，使由沉积物自然固结压实引起的地表形变具有显著的空间差异；目前，除清水沟流路叶瓣表现为快速沉降以外，其它滨海沿岸区基本上都表现为微弱的下沉。自然状态下三角洲平原的地面沉降分布主要受中―高压缩性软土层和黏性土层固结沉降的控制，分别占沉积物总固结沉降量的40～95%和3～12%（或30～50%）。三角洲平原区沉积层的自重固结沉降已进入后期缓慢沉降阶段，软弱土层的性质及厚度是控制本区不均匀沉降的主导因素。黄河新近沉积物的自重应力对海底浅层沉积物和前三角洲沉积层的固结压缩影响较大，特别是海底淤泥和淤泥质土层在受压初期会发生快速固结压缩，足以引起明显的地表下沉。近几十年来，因区域构造运动和均衡运动引起的地表绝对下沉速率约为3.42 mm/a。该区地面沉降的时空差异性及其在相对海平面上升中的叠加作用，不仅关系到三角洲的垂向发育过程，且对黄河尾闾的摆动、下游河道的淤积、海岸侵蚀和潮滩冲刷等方面都有着重要的影响。
其他摘要	In allusion to land subsidence in the modern Yellow (Huanghe) River delta, this paper addresses the recent characteristic, the factors and its effects to delta of this problem, in light of leveling data, nearby tide gauge records, the soil mechanics parameters of the seafloor and the delta sediments, remote sensing interpretation, results published in literatures analyzed integrated with GIS tools and so on. The results of repeat leveling from 1964 to 2007 covering the whole delta and the SAR data covering southern of delta from 2007 to 2008 acquired by the ENVISAT calculated using Differential Interferometric Synthetic Aperture Radar（D-InSAR）show the variability of the surface depression in the study area. The rate of subsidence has been decreasing from area near vertex of delta to the coastal zone and some place is even rising, particularly in the early formed area. What is the different in the coastal is that the rate of subsidence is still high and can sustain a long time. This is because the land subsidence in the delta is mainly caused by the consolidation of sediments if there is no human activity. Especially in the newly formed area, Qingshuigou sub-delta, the rate of subsidence was more than 50 mm/a in the begining and now is still higher than 10 mm/a. When the newly sediments discharged by the Yellow (Huanghe) River landed on the subaquatic delta, its load can drive the concolidation of the silt, which is on the surface of the Bohai seafloor. The rate of consolidation of the silt will be decreasing quickly in the first years, but still a long time in the later time with a slow rate. Consolidation of soft soil, which is caused by its weight in the natural state, is the main proportion of the ground settlement in the plain area, account for 40-90 % of the total settlement, while that of the upside silt is only 3-12 % or 30-50 %. As a result, characteristic of distribution of the Land subsidence is controlled by the thickness and the depth. Calculation of the consolidation rate show that the consolidation maybe approach to complete recently, but it will be still the main factor if there is superfluity load by human activity. From the result of relative sea level change in the delta by a stochastic dynamical prediction model, the rates of land subsidence is about 3.42 mm/a, which is mostly resulted in diastrophism and will continue a long time. The rate caused by tectonic is about 2.0 mm/a, while the other is caused by isostasy as a result of burden of sediments after 1855. With an accumulating land subsidence, it can change the surface slope, consequently influenced the riverbed and estuary evolution. Additionally it increased the rise of the relative sea level, as a result changed the models of coastal erosion and forced the coastline retreat landward or narrowed the tidal flats at an accelerating rate with the strengthened hydrodynamic action.
页数	131
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/891
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	杜廷芹. 现代黄河三角洲地区地面沉降特征研究[D]. 海洋研究所. 中国科学院海洋研究所,2009.

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