长江三角洲地区海面—地面系统模型构建与试验

Construction and experiment for sea-level & land surface system model in the Yangtze Delta Region

本文从海面-地面系统研究的视角出发,介绍了由滑动底界计算、分段沉积速率计算、古地面高程计算和模拟结果验证等四个基本模块构成的海面—地面系统模型的基本构架,阐明了该模型的数据分类系统、基本功能目标及其实现的技术系统。初步建成的该系统模型,可以通过对海面变化、沉积作用、地壳运动等多种控制参数的调控,自动生成相应控制条件下任意指定时刻或时间段的二维、三维古地形图等多种形式的图件,因而可以用以对三角洲平原古地貌和海陆关系演变历史进行动态演示,并且为专业人员开展三角洲古环境反演研究和虚拟实验提供一种新的平台。根据长江三角洲地区的实际资料,运用该模型对最近一万年以来的海面—地面变化过程进行了初步的模拟试验,从模型输出的分层设色古地形图和三维彩色地貌晕渲图来看,效果良好。

The S/L （sea-level and land surface） system change plays a very important role in the evolution course of natural and human history in coastal area, so it may be an effective solution to study the environmental evolution and human-land relationship development in the Yangtze delta region by performing a virtual experiment on the platform, which relates to the consolidation of the S/L system integrated study and the construction of a digital and visual S/L system model. From the visual angle of the S/L System, this paper introduces the basic framework about the S/L System model, which is composed of four modules： the sliding bottom boundary calculating, segmentation rate of sedimentation calculating, the ancient land surface elevation calculating and simulated result validating, and throws light on the model＇s data classification system, as well as the model＇s basic function aims and on the model realized technology system. Using the DEM and GIS technology, through regulating the variable multi-parameters of sea level changes, sedimentation, crust movements and so on, sorts of maps can be automatically created by the preparatory system model, such as 2D or 3D paleotopographic maps, which are compiled respectively according to the control conditions of the randomly designated time or time intervals. Hence this can be used to dynamically demonstrate the delta plain＇s paleogeomorphology and sea-land relationship evolution history, besides providing the professionals with a new platform in the delta paleoenvironmental reconstruction and virtual experimental study. Based on the existing data of the Yangtze delta region, a preparatory simulative experiment was done by the model on the sea-land change course in the Yangtze delta region since 10000aBP. The good simulative effect is obvious from the hypsometric paleotopographic map and 3D color shaded-relief map, both the output of the model. This pro-vides a visual scene to analyze and discuss the Yangtze delta evolution, coastline shifting,even the relationship between the ancient civilizations migration and environments.