Research On The Effect Of Terrain On Snow Distribution And Characteristics In Changbai And Wanda Mountain Hilly Area

Snow,as the most active and multi-characteristic natural resource on the surface of the earth,is the most widely distributed natural element in the cryosphere and the most significant seasonal variation.it is also the main form of winter precipitation in northeast China.The distribution and properties of snow cover have a significant impact on snowmelt erosion.at present,there is no systematic evaluation mechanism of snowmelt erosion in China.In Changbai and Wanda mountain hilly area,the topography is complex,the fluctuation is bigger and the area of sloping farmland is more.the speed of thawing erosion of sloping farmland in spring is no less than that of soil and water loss caused by heavy rain.snowmelt erosion has become an important cause of soil and water loss of sloping farmland in this area.therefore,this study takes Changbai and Wanda mountain hilly area as the research object,and uses the methods of indoor data analysis,field measurement and outdoor simulation to study the distribution and properties of snow cover.Firstly,based on the snow depth data retrieved by passive microwave remote sensing,combined with the terrain data such as slope,aspect and elevation in the study area,the change process and spatial distribution characteristics and influencing factors of snow depth in Changbai and Wanda mountain hilly area during 2013-2015 were analyzed.it was found that the snow amount and the distribution of sunshine hours and average air temperature in snow period were the primary reasons for the difference of the inter-annual snow accumulation,and the air temperature was the main influencing factor of snow accumulation and distribution in large scale range.the change rate of snow depth in the study area during 2013-2015 showed a trend of " large-small-large" with the increase of slope Secondly,using snow fork snow characteristic analyzer to collect snow physical properties data,analyze the change trend,differences and causes of snow characteristics in different slope positions of typical small watershed in the study area.it is found that the primary factors affecting snow characteristics differences in different slope positions are solar radiation,wind speed,wind direction,air humidity and uphill snow melting on downhill slope is an important factor causing snow characteristics differences in different slope positions.the snow properties influence each other,there is a certain relationship between each other.snow density and liquid water content affect the snow internal structure,and the snow internal structure affects snow depth to a certain extent.In order to determine the main topographic and climatic factors affecting the snow characteristics of slope area,the outdoor simulation experiment was conducted by using the combination of 5 slopes,8 aspect and the solar altitude angle at different times during the experiment period.the change law of snow anti-radiation illuminance with the slope,aspectand solar altitude angle was analyzed.it was found that the slope and aspect and other topographic factors affected the solar radiation intensity and sunshine hours,and the solar radiation intensity was directly affected by the solar altitude angle,and the greater the solar altitude,the more difficult to block each other between different slope slopes,the steeper the slope,the shielding effect was more significant.Finally,a prediction model of slope snow characteristics in Changbai and Wanda mountain hilly area was established by using regression analysis method combined with field measured data of slope snow characteristics and snow anti-radiation illuminance.The main innovation of this paper is to analyze the differences and relationships between the physical properties of snow from the microscopic point of view,and quantify the effects of slope,aspect and other topographic factors on the characteristics of snow,revealing the continuous and dynamic change process of snow density and liquid water content,It lays a theoretical foundation for snowmelt erosion mechanism research,snowmelt erosion prediction and soil and water conservation measures.