The Modeling Simulation Experiment About Sea-Level And Land Surface Changes Over The Past 10 000 Years In The Changjiang Delta

The Yangtze delta area is one of the most economic-developed and populous areas in china, and it plays an important role in economical development of China. Today mostly deltas were developed by the global marine transgression and the sea level changes drive in Holocene, which have been intensively reconstructed by the human activities in present, which have recorded a great deal of information about the Holocene environment evolution, so the deltas is also a typical region in the physical geography process study. As a geoscience's research tool, Geographical Information System (GIS) has put great impulse in geographical research on the aspects of digital, quantitative, modeling, experimentation and visualization, and have profoundly changed the traditional research methods. It provides some possibility to lots of research ideas to come true, which seem to be unable by the traditional means in the past.Under the condition that there have been accumulated lots of materials and research findings about sea level change, sedimentology, stratigraphy and palaeogeography in china coastal areas, it is a deserve attention problem on how to clear up the different academically options and resolve the difficulty problem. The S/L (sea-level and land surface) system change act as a very important role in the course of natural and human history evolution in coastal region, so it's may be an effective solution to study the environmental evolution and human-geo relationship development in delta region by performing a virtual experiment upon on the platform, which relay on consolidating the S/L system integrated study and constructing an digital and visual S/L system model. In the research, Yangtze delta is the research object, grid DEM is the basic simulation data, GIS is the basic simulation platform, Holocene is the research timescale, the S/L system is the visual angle, through analyzing the S/L model and S/L system's interrelated elements in Yangtze delta, the study has set up a model simulation experimental method, which to be used to reconstruct the delta geomorphology evolution. The study has succeeded in the reconstruction and inversion about Yangtze delta evolution by the digital, quantitative, modeling, experimentation and visualization research method in the past 10000 years.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 map, which are respectively according to the control conditions of the randomly designated time or time intervals, so it can be used to dynamically demonstrated the delta plain's paleogeomorphology and sea-land relationship evolution history, besides it provides the professionals with a new platform in the delta paleoenvironment reconstruction and virtual experiment study.Based on the existing data of the Yangtze delta area, a preparatory simulative experiment have been done by the model on the sea-land change course in Yangtze delta area since l0000aBP, and a good simulative effect are obvious from thehypsometric paleotopographic map and 3D color shaded-relief map which exported from the model. That provides a visual scene to analyze and discuss the Yangtze delta evolution, coastline shifting, even the relationship between the ancient civilizations migration and environments.The qualitative analysis on the model simulation's results have done by using the spatial distribution of archaeological sites and shell dikes respectively, and the quantitative analysis by archaeological sites, which include two types archaeological sites, one type is stages archaeological sites and the other is with the 14C dating data, which have been corrected by tree-ring. In order to acquire the best ratio about the mean sedimentary velocity of the early Holocene, the mid-Holocene and the late Holocene, firstly, to calculate the palaeoland elevation by the S/L simulation model about the 73 archaeological sites with the 14C dating data, then from the aspects of palaeoland elevation, mean palaeoland elevation and population variance. At last, the NO. 12 ratio project was been estimated as the best ratio project, which is very close to the NO. 13 ratio project, which was been selected by the expertise.