关键词: InSAR, 永久散射体雷达干涉测量, 现代黄河三角洲, 地面沉降

Abstract:

Currently, with the influence of long term exploitation of oil, gas, groundwater and brine resources, the increase of surface load and the compaction of recent sediments, ground subsidence has become one of the main geological hazards of the modern Yellow River Delta, China. Wetlands are broadly distributed , and most areas are covered by vegetation in this region, which make monitoring more difficultly. This article introduces monitoring of ground subsidence in the modern Yellow River Delta area using PSInSAR technique. To carry out experiment 10 ERS1/2 images during June 1992 and August 1995 were collected, and with Hooper’s PSInSAR algorithm model, more than 80 000 PS points were selected. 3.0 was chosen as the threshold of standard deviation to screen the PS points, and PS points were drop out which were affected by noise. PS points that in Dongying airport were chosen as reference points to correct the results, then the mean subsided velocity map and the deformation quantity in time series were derived.Ground subsidence phenomenon are widely distributed in the modern Yellow River Delta area.The mean subsided velocity is about 4.4 mm/a in most coastal area, mean subsided velocity of Shengli Oil Production Plant and its surrounding areas is 10.1mm/a. In the west city district of Dongying the value is 7.1 mm/a and in the east city district of Dongying the value is 7.4 mm/a. Subsided velocity map, the residential map and oilfield distribution map were overlapped to analyze the relationship between them. The results show that subsided velocity of the modern Yellow River Delta has high correlation with exploitation of oil, the increase of surface load and natural compaction of sediments.The accuracy of PSInSAR technique was verified by traditional Leveling data. Four leveling points were taken near PS points. Although the monitoring time interval and location of Leveling points was not in full accord match with PS points, the monitoring results gotten by PSInSAR technique was consistent with the leveling results. The subsided quantity curve of one leveling points which were 80 m distant from the nearest PS point and monitoring during the same time interval is very similar with the PS point’s subsided quantity curve, and the mean square error between them is 0.88 mm, so the mean square error gotten by PSInSAR technique was within the bounds of millimeter level. The results show that PSInSAR technique based on small data set can be used to monitor ground subsidence either the area is vegetation covered or wetland area, if only it have stable scatters.

Key words: InSAR, Permanent Scatters InSAR, the modern Yellow River Delta, ground subsidence