Correlation Between Spatiotemporal Evolution Of "Patchy Bare Land" And Geomorphological Factors In Zoige Basin

The Zoige Basin is located at the source area of the Yellow River and is known as the "oasis of the plateau in northwest Sichuan" and the "reservoir" of the Yellow River.It plays an important role in maintaining the balance of the ecosystem,water conservation,protection of species diversity,and climate regulation.Wetland degradation and desertification due to the dual effects of natural environmental changes and unreasonable human activities have become one of the most serious ecological and environmental problems in the Zoige Basin.The investigation and monitoring of bare land can timely and effectively monitor the occurrence and area changes of bare land,and is an important basis for studying the formation mechanism of bare land and predicting the change trend of bare land area.It is also important for controlling the spread of bare land and ensuring the social economy and ecology of the region.Sustainable environmental development is of great significance.From the perspective of studying whether the spatial changes of natural bare land in the Zoige Basin correspond to the geomorphology in the basin,this paper uses TM images to extract the bare land in the Zoige Basin during the four periods from 1990 to 2016,and conducts statistics and analysis based on the geomorphological unit data.Look for the correlation between the evolution of bare land in Zoige Basin and geomorphological factors.The research results of this paper are as follows:(1)Distribution of landform types in Zoige BasinThrough the extraction and analysis of the geomorphological types inside the Zoige Basin,a total of 42 types of micro-landforms in the Zoige Basin are obtained,and the Zoige Basin’s landforms are classified according to altitude,camp strength,and topographical ups and downs.According to the classification of altitude,the Zoige area is divided into two types: high-altitude landforms and middle-altitude landforms,with high-altitude landforms being the main landform type.According to different forms of camping force,Zoige Basin is divided into lacustrine landforms,flowing water landforms,periglacial landforms and glacial landforms.According to the difference of topography,the geomorphic units of Zoige Basin are divided into 6 types of topography: plain,platform,hill,small undulating high mountain,medium undulating high mountain and large undulating high mountain.The 42 types of micro-landforms are divided into 17 types of landforms.It is concluded that the interior of the basin is mainly composed of middle-elevation lacustrine plains and high-altitude flowing water hilly landforms.The outer edge of the basin is mainly high-altitude flowing water eroded mountains and highaltitude periglacial eroded hills and alpine landforms.(2)Spatial distribution characteristics of bare land in geomorphic units in Zoige BasinThis paper uses Arc GIS software combined with Zoige Basin to carry out geomorphological type distribution and zoning statistics of the bare land from 1990 to2016 in Zoige Basin,and summarizes the spatial distribution characteristics of the bare land in the geomorphic units of the Zoige Basin through statistics in 2016,and compares and analyzes the bare land in the geomorphic units.Area and bare land ratio.The bare land in the geomorphic units of the Zoige Basin is divided into naked land concentrated area,’high naked area’ and’low naked area’,among which there are 7 micro-landforms and’high naked area’ in the naked land concentrated area.There are a total of 5geomorphic units and a total of 27 micro-landforms in the’low bare area’.Through statistical analysis,it is concluded that the spatial distribution of bare land decreases with the increase in altitude and relief.The landform unit with the most bare land is the mid-elevation alluvial river floodplain.The high-altitude glacial valley plains and the high-altitude glacial margins are distributed in large undulating steep mountains without nakedness.(3)The effect of Zoige landform factors on the evolution of bare landThe area of bare land in high-altitude terraces,large undulating mountains,and middle-altitude terraces is small and the proportion is small,and there is no obvious change in each year;the difference between the total area of bare land and the total area of bare land in the middle-altitude current level is that the difference is that The area has been decreasing from 1990 to 2016;the area of bare land in several types of landforms such as high-altitude running water hills,high-altitude periglacial plains,and highaltitude periglacial undulating mountains has been increasing from 1990 to 2005,especially high The area of bare land increased by 15.95Km~2 from 1995 to 2005,and the area decreased by 15.17Km~2 from 2005 to 2016,with a range of change of more than30%.For the rest of the landform types,the bare land is distributed in the basin and the total bare land changes in the same trend.