Study On Topography And Geomorphology Of Xiamen Bay And Its Adjacent Regions

The bay is a part of coast which stretches into mainland or islands, it locates in land-sea transition zone, has a great significance for human's development. This study data is derived from "China 908 marine environment survey and assessment" special project, including bathymetry data, shallow stratum profile and side scan sonar pictures, sediment data and so on. Combined with the natural environment, hydrodynamic characteristics and regional geology, a detailed description and analysis of topography and geomorphology of Xiamen Bay and adjacent regions were made. The landscape system of the study area was set up by the principles of landscape classification and landscape classification system. Brief analysis on geography and geomorphology process of the study area in recent 20 years and its influence factors on landscape development based on comparing and analyzing the different of the topographic feature between 1985 and 2009 ( the relief maps in 1985 is from china's coastal survey map) have been achieved. The conclusions were acquired as follow:A. Xiamen Bay and its adjacent regions with many sub-island bays inside are affected by a strong tide action. The tidal range and tide current speed is obvious and thus its dynamic action is strong. The main topography of waterway showed many erosion grooves and submerge reef on its bottom. When the hydrodynamic force turns weak, lots of sediment carried by tide current would settle down, sometimes submarine ford are formed.B. Submarine geomorphology in the study area has many tapes, including tidal flat, beach, modern estuary subaqueous delta, submarine slop, tidal sand ridge, tidal delta, continental shelf plain, artificial landscape, channel, submerge reef, waterway, estuarine sandbar, submarine ford, paleochannel and so on. A tidal sand ridge and submerge reef group was discovered at first time. The newly discovered submerge reef group and tidal sand ridges has a great significance for local geomorphology diversity.C. By comparing physiognomic maps from 1985 and 2009, the process development of geomorphology could be analyzed. Tidal flat and beach in study area had been transformed by human being. Lots of tidal flat formerly locating on the side of Xiamen Island and in Tong'an bay disappeared, and the beach had grown in some extent. The modern estuary subaqueous delta and tide delta had grown greatly, with shape from fan-shape to tongue-shape.D. The tectonic movement provided a basic framework for geography and geomorphology, however, the sea level changing, deposition and hydrodynamic changing affected the geomorphology forming later. Afterwards, human beings modified the landscape strongly forming some artificial landscapes.