三峡水库的建立对库区地球重力场及地壳形变的影响

作为人造工程的三峡水库的建立，使得库区水体聚集，地球质量重新分布，将使地壳的物理结构以及局部地球重力场发生变化．针对上述问题，对库区的水准面、点绝对重力值、垂线方向和高程、高程基准面等的重力场变化以及地壳形变进行了研究．主要结果是：当蓄水水位达到峰值１７５ｍ（坝高）时，大地水准面有２．２３－１１．２ｍｍ的变化，点重力值有（０．８３－４．６）×１０^－５ｍｓ^－２的变化，垂线偏差的变化分别为－０．６２＂－６．５０＂（南北方向）和－６．４２＂－１．３４＂（东西方向）地壳的形变量为１．３２－６．６５ｍｍ，这些变化将引起测区的高程产生３．５５－１７．８４ｍｍ的变化．因此，原有库区及其附近的测量资料（包括水准、天文、重力等）必须审慎使用，并应建立库区形变监测网，对地壳形变、地震、滑坡、大坝变形等进行监测．

GRAVITY FIELD VARIATION AND EARTH CRUSTAL DEFORMATION IN THE THREE GORGES AREA DUE TO THE WATER LOADING OF THE YANGTZE RIVER

As one of the world biggest reservoirs, the Yangtze River reservoir, will be established in China in the near future. The accumulation of the water body mass will cause the redistribution of the earth mass. The local geophysical structure of the earth will be changed. Thus, the local gravity field and the levelling datum variations, as well as the earth crustal deformation, will occur in the Three Gorges area.In this paper, all of the above problems are discussed theoretically and evaluated numerically. The study results show that the equipotential surface (and geoid), gravity vector (value and direction), spirit levelling result and the earth crustal deformation will be changed significantly. So it is very important for geodesists and geophysicists to establish some monitoring networks and to study the problems such as earthquake, slip-off slope, deformation of the big dam and the geophysical structure of the earth crust. The influences on the original geodetic observations such as gravity observations, spirit levelling data, astrogeodetic observations and GPS satellite observations, should be reconsidered carefully and corrected.