长江三角洲地貌演变模拟模型的构建

从海面-地面系统出发,对三角洲地貌演变模拟模型进行了完整构建,它是包括地面高程、沉积厚度、地壳垂直运动速率与古海面波动等在内的多变量地学过程模拟模型。根据长江三角洲地区的实际资料,运用该模型对长江三角洲全新世时期的地貌演变过程进行了初步模拟,从模型输出的各时期古地貌图来看,效果良好。模拟结果表明：以太湖平原为主体的长江三角洲平原南部区域的地貌演进过程可大致以7000 a BP和3000 a BP为界划分为早期快速海侵,中期岸线反复摆动,晚期迅速海退三个阶段;太湖平原核心区始终未曾遭受过大规模海侵,基本保持为陆地环境,但太湖平原西缘和太湖湖盆等部分区域可能曾数度受到过海侵的影响。分别利用304个分文化期考古点数据和73个考古点测年数据对模拟结果进行了定性和定量验证,验证结果表明：模型对全新世长江三角洲古地貌和海陆关系演变的模拟结果有较好的可信度。

Construction of the Simulating Model for Geomorphic Evolution of the Yangtze Delta, China

Based on the existing data of the Yangtze delta area, a preparatory simulation has been done by the model on the Holocene geomorphic evolution in the Yangtze delta area, and a good simulative effect has been observed from the paleotopographic maps, which are generated from the model. The simulation shows that (1) the coastline evolution can be divided into three stages by taking 3000 aBP and 7000 aBP of the Holocene as a divide, the early stage is a rapid transgression stage, the middle stage is a transgression-regression repeated fluctuating stage and the late stage is a transgression stage; (2) the core region of the Taihu lake plain maintained basically a land environment all through the Holocene, not being suffered from large-scale transgression. But it is quite possible that transgressions have happened in the western part of the Taihu lake plain and part of the Taihu lake basin. In order to validate the simulation modeling, we have conducted qualitative and quantitative analyses from different aspects using data of the 304 archaeological sites in different cultural periods and the 73 14C dating data corrected by tree-ring. The validation results showed that the simulation method is a preferably reliable one to reconstruct the Yangtze delta geomorgraphic evolution and the simulation results are believable. So this study has set up the model simulation experimental method based on the GIS/DEM technology, which can be used to reconstruct and inverse the delta geomorgraphic evolution.