The Precision Digital Landform Construction In Coastal Zone Based On Multi-source Data

Coastal zone is the interaction of sea and land area,the individual with the attributes of both the land and sea.The geomorphic features of coastal zone is related to the sustainable development and utilization of the coastal zone.Therefore,coastal zone landform study not only can provide data for the development and the management of the coastal zone,but also can provide decision-making for the construction of the coast.Due to the special position of the coastal zone,the traditional research is mostly a single research in underwater topography and land landscape of the coastal zone.In this paper,based on multi-source data(including the DEM in the study area,GF-1 satellite remote sensing images,aerial images,chart data,sediment data from the field,intertidal zone size),combined with computer technology,remote sensing and statistical methods,to construct the integrated coastal zone landform of Dingzi Bay and carries on the quantitative analysis on the landform and surface coverage.Through the research and analysis,the work of this paper and the results are as follows:(1)According to field survey data,and the 908 landscape classification system,the paper has adjusted some classification standards,supplemented the coastal geomorphic types,and puts forward the coastal zone landform classification system which suitable for Dingzi Bay.According to different position,the coastal zone landform can be divided into land landscape,intertidal zone landform and the ocean floor.Land topography is the land above the coastline,including the plains,hills,low-relief mountains and mesorelief mountains.Intertidal zone is the area under the coastal zone to the lowest tide level surface local,including tidal flats,beaches and rocky beaches.Sea floor is the regional landscape below the lowest tide level surface local,which including underwater slope,submarine shoal,tidal inlet,sand wave and ebb delta.(2)According to the proposed system of coastal zone landform,this paper develops a multi factor method for extracting land natural terrain based on DEM.The results show that the combination of the fluctuation of classification can eliminate plain mutation(the edges of the building and coastal edges)fault and improve the accuracy of classification of the natural landscape.Based on this method,we get the coastal land natural topography results;This paper also develop the method of NDWI index method and SVM method for extracting small pond waters.This method can eliminate the false part of the building.What's more,this paper use visual interpretation of aerial image and NDVI threshold method to extract building,farmland,forest cover.At last,we make the results of land artificial landform.(3)This article based on water depth and depth contour which extracted from the chart,using 10 kinds of interpolation methods for depth interpolation.The accuracy of the interpolation result evaluated by check points and contour playback method.Considering the ability of different methods in different water depth interpolation accuracy and reduction of the terrain,this paper proposes a construction method of seabed terrain based on piecewise optimal interpolation.This method can make up single interpolation methods,improves the interpolation accuracy of underwater terrain.Based on this method,the results of the submarine topography in the Dingzi Bay are generated,and the underwater topography of different water depth is reduced accurately.(4)The submarine topography and altitude datum have different benchmark data,this paper research the relationship between the elevation of the lowest tide level surface in Dingzi Bay and the geoid.Based on the relationship between two datum planes,the water depth data have been modified,and unified submarine geomorphic to the land geomorphic.Based on the unified datum,we can get the integrated digital geomorphology.With the integration of digital terrain,this paper analyzed the influence of surface morphology on plain,non-plain,forest land and cultivated land,make sure the distribution of geomorphic types in intertidal zone is determined,and analyzed the submarine geomorphology.