| After a long term study of the alluvial fan,it is found that the development of alluvial fan is controlled by many environmental factors such as drainage basin geology,tectonic activity,climatic conditions,base level change,… And alluvial fan in different regions differs in thousands ways.As a typical area of alluvial fan in Northwest China,the fan body is diverse and well deserved,but the research degree of alluvial fans in this area is low due to the influence of natural geographical conditions and traffic convenience.GIS technology can quickly acquire large amounts of data,and can process and analyze spatial information well.It is an effective means to research alluvial fan geomorphology.We took alluvial fans developed in Mingtiegai Area,Xinjiang as the object of study.In this paper,GIS technique is the major measure to get the data we need about the geomorphology features of alluvial fan.We collected multi-source geological data and multi resolution remote sensing data,and we also take some field exploration at typical areas.The basic geology features of fan are compared and analyzed by the methods of human-computer interaction interpretation and statistical calculation,and we summarized the geomorphic features and topographic rules of alluvial fan.The main results obtained are as follows:First,the fan area in Mingtiegai is divided into three regions according to geological location,and great morphological differences between alluvial fan in these areas are found.The alluvial fans in east sector have the features of largest fan area and fan apex,with the lowest slope and the middle height difference.But alluvial fans at north sector have the lowest fan area and height difference,with largest slope and middle fan apex.And,we established and compared the alluvial fans in three region using the basin parameters,which proves that the alluvial fans in west sector have the highest development degree of fan area and the north sector has the lowest degree compared between the three regions.Secondly,we studied the relationship between the inner parameters of alluvial fan.The distance between alluvial fan top and piedmont river can represent the effect of piedmont river to the alluvial fan,and its correlation coefficient with fan area can be used to judge whether the alluvial fans have enough space for development.It is also found that if the development space of alluvial fan is insufficient,the development degree of fan area will also be low.Then,the study on the relationship among the area of alluvial fan,the area of the drainage basin and the glacier areas of allvial fans with low moraine shows that the glacier can weaken the denudation of the bedrock in the drainage basin and reduce the effective area of alluvial fan.Compared with the same area,the weakening effect of glacier is the largest in the western region,the second in the north region and the smallest in the eastern region.In addition,the analysis of the soil types of alluvial fans shows that the drainage basin elevation,height difference of the basin and the geological types of the fan are the main factors affecting the type of the alluvial fan.And the three parameters can guide the classification of the soil types of alluvial fan. |
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