The Research of Hydrogeologic Framework and Land Subsidence in Taipei Basin
Date Issued
2012
Date
2012
Author(s)
Lin, Ming-Hsuan
Abstract
The political and economic center of Taiwan is located in the Taipei basin, and many of the subsurface excavations are done now. In this study, we collected the borehole core data and groundwater level record of the Taipei basin from 1976 to present, and use the elevation data to find the relation between groundwater level and land subsidence.
By analyzing the groundwater level record, we found 2 water level changing patterns, which can be identified by the 0m water level to two parts, the upper-part and the lower-part. The upper-part groundwater level is relative to the rain fall, but is a little bit different in every location. The lower-part groundwater level is from -40m to 0m, but human activities are highly relative with water level change. Comparing the depth of wells with core data, well screens are located in thin sand layer of Songshan formation, or Jingmei formation, or Wugu formation. The sallow wells are almost in the Songshan formation, where the deep wells are in the Jingmei formation or Wugu formation.We think there are 2 hydrogeological units in Taipei basin, which are Songshan formation and the combination of lower Songshan, Jingmei and Wugu formation.
During the last decade, periodical pumping and recharging cause the water level to fluctuant. Short-term water level variation becomes the primary factors for land elevation change. We found out the reason for subsidence and uplift is the elastic rebound. Although there is time lag, the contrast between the groundwater level and the land elevation is easy to perceive.
Subjects
Taipei Basin
hydrogeology
framework
land subsidence
Type
thesis
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