水域地形改正方法研究  

Study on topographic correction of water area

作　　者：韩革命[1] 杨亚斌[1] 梁萌[1] 

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000

出　　处：《地球物理学进展》2012年第4期1693-1700,共8页Progress in Geophysics

基　　金：国家"863"课题(208AA06Z104);国家地质矿产调查评价项目(1212010050235)

摘　　要：在区域重力调查工作中,地形改正误差对重力异常总精度影响较大,是提高布格异常总精度的关键因素.在以往的区域重力工作中,遇到河、湖等水体时,因为条件所限,通常将水域视为与地形改正密度相同的物质,对岸边点不进行水体改正,无形中对重力异常的精度产生了影响.随着技术进步,对地形改正精度要求越来越高,故,需要进行精细的地形改正.水体作为特殊的地表覆盖物,具有较大规模时,成为不容忽略的影响因子.根据本文评估计算,平均水深达20m、水面宽度达2km时,水体对测点的影响已经接近或超过现行规范的精度要求.所以,当遇到水深大于20m的青海湖、水深达到100m的纳木错等大型湖泊时,传统的、忽略水体影响的工作方法已不能满足精度要求,需要消除水体对测点产生的影响.本文给出了用计算机进行水体改正的具体方法:用DEM数据和水体深度资料,采用共用点法计算出进行了水体改正的地形改正值和水体改正值.并用模型数据进行了水体改正计算,根据计算结果对水体改正值进行了定性分析,得出结论:1)水体改正方法正确、简便,可应用于重力调查工作;2)当水体的平均厚度达到20m以上时,在区域重力工作中,必须考虑进行水体改正;3)水体改正值与测点距水体的距离、测点周边水体面积大小、水体边界形状、测点海拔高程和水底地形等因素有关.即,在以下情况下水体对测点的影响值增大:测点距水体距离减小、测点周边水体面积增大、测点位置突入水域越多、测点高程越接近水面高程、水底地形越陡.In the regional gravity survey, the influence of topographic correction error on total anomaly precision is great and it becomes the key factor of improving topographic correction error. In the past, when meeting rivers, lakes or other water bodies in the regional gravity survey, we regarded the density of them as the same density of material that was used in the topographic correction because of condition restriction, which would influence the gravity anomaly precision. With the development of technology, the topographic correction precision demand is improving. So we need do fine topographic correction. The large scale water body, as special surface mulch, becomes the factors that cannot be ignored when we calculate the fine topographic correction. According to the assessment of the water of average 20 meters deep and 2 kilometers wide in this paper, the influence has been close to or more than the current specification accuracy. When meeting big water bodies such as the Qinghai Lake which is more than 20 meters deep or the Namco Lake, the traditional work method ignores the influence of water body and can not meet the need of precision, so we have to eliminate the water impact. This paper discusses the method of water body correction. We use DEM data, water depth data and the method of common point to calculate the topographic correction that includes the influence of water body correction and analyses of the water body correction qualitatively. We get conclusions as follows. 1） The water correction method is right and simple, and can be applied to the gravity survey. 2） When the water depth reaches 20 meters, the gravity survey must include the water correction. 3） There are many factors which will effect the water correction, such as distance between station and water, the water area around the station, the shape of water boundary, the altitude of station and terrain of underwater etc. So we can say that the influence of water body will increase in the following cases： the distance between the statio

关 键 词：水体改正 地形改正 

分 类 号：P631[天文地球—地质矿产勘探]