为全面和具体地了解整个黄河三角洲的地面沉降状况,收集了现代黄河三角洲地区1956、1967、1980年1:5万比例尺的地形图资料,利用地理信息系统软件进行数字化、建立高程数据库,生成数字高程模型。通过对不同时期数字高程进行空间运算发现,1956-1980年间黄河三角洲地区地面沉降现象普遍,沉降区年平均沉降数厘米。基于数字高程空间分析结果,探讨了诱发三角洲地面沉降的自然和人为因素。
Three digital elevation models(DEM) were generated from 1:50 000 topographical maps of the Yellow River delta,whlch was surveyed in 1956,1967 and 1980,respectively. Knowledge of ground subsidence in the delta from 1956 to 1980 was obtained through spatial analyses of these DEMs,and three major impact factors of ground subsidence were addressed. The results show that ground surface of the Yellow River delta experienced a widespread subsidence during the past 24 years, with an average rate of several centimeters per year in the subsidence areas. Neotectonic sinking had a faint but persistent influence on ground subsidence in the Yellow River delta. Consolidation of deposits,a major cause of ground subsidence in the delta before the Yellow River switched to the Qingshuigou course,induced sheets of subsidence. Human activity played an increasing role in ground subsidence in the delta with the rapid development of oil industry and the over-exploitation of underground water, which usually induced small points of subsidence at the beginning and then gradually expanded to the whole region.