Study On The Effect Of Seasonal Frozen Soil Thawing On Snowmelt Flood

There are many factors influencing snowmelt runoff,but the data obtained are not ideal because of the uncertainty of hydrological process and the single field monitoring method.At present,the research of snowmelt runoff process and its influencing factors is still in the immature stage,especially the influence of frozen soil thawing on snowmelt runoff.In this paper,widely exists in the juntanghu basin on the northern slope of Tianshan Mountain of seasonal frozen soil as the study area,in the seasonal frozen soil in the snowmelt period under the condition of the existence of the premise,combined with the analysis of the field observation and indoor analysis,using the method of hydrology,mathematical statistics and multiple data of seasonal frozen soil temperature and soil moisture were analyzed with the change of time and depth of frozen soil,and the correlation analysis of soil moisture and temperature;infiltration test of seasonal frozen soil under the condition of soil water infiltration capacity by double ring;the major influence on snowmelt runoff factor analysis.The main influencing factors of this research are analyzed:(1)by analyzing the physical characteristics of soil samples,it is concluded that the experimental field is dominated by silty loam,and the permeability becomes worse with the increase of soil depth.In the freezing thawing process of seasonal frozen soil,the soil temperature variation of soil temperature in shallow layer is more intense,small changes in deep soil temperature,indicating shallow soil affected by the outside world,and the deep soil affected by the outside world is small.As the air temperature is low,the soil begins to freeze downward from the surface layer.During the melting period,the frozen soil is melting simultaneously from the upper and lower layers due to the ground surface temperature and the geothermal heat at the bottom.(2)during freezing thawing soil water content curve was concave shape,namely,the soil water content was decreased gradually,and then fell to the lowest point of slow growing phenomenon;freezing temperatures continue to reduce,the soil temperature also decreased,when the temperature at the depth reached its freezing temperature,the soil in a part of the liquid water freezing,soil water content began to decrease;the melting period,solar radiation gradually strong,the temperature rise of soil,the soil layer soil moisture content increased.The correlation analysis of each layer of soil water and heat,the relationship between soil water content and temperature is higher,especially in the 10-20 cm soil layer correlation coefficient as high as 0.908,with the increase of the correlation coefficient of soil depth decreasing phenomenon.(3)double ring infiltration test was carried out in different frozen soil during snowmelt period.The permafrost is equivalent to a water resisting layer,prevent snowmelt infiltration;infiltration amount is lower than the infiltration amount of unfrozen soil freezing soil;infiltration rate and infiltration rate is lower than the non frozen soil freezing soil;frozen soil stable infiltration rate is less than the non frozen soil;seasonal frozen soil with the increase of temperature reduction of infiltration capacity weakened with the increase of the depth increased.It shows that the seasonal frozen soil has the characteristics of seepage reduction,and the permeability is related to the air temperature and the depth of frozen soil.(4)analysis during snowmelt.By contrast,there is no seasonal frozen when the amount of runoff,that there are a lot of permafrost in the snowmelt period,snow flow intensified the effect of surface runoff,and when a permafrost melting,Rong Xueshui infiltration increased,infiltration intensity increased,inhibited the snowmelt runoff,reduce runoff;after analysis there is no seasonal frozen soil,the relationship between soil moisture and runoff that snowmelt infiltration by regulation of soil,a frozen soil prevents the snowmelt water infiltration,on the one hand,when the temperature rise effect makes the thawing permafrost melting a large number of water infiltration changing the moisture content of the surface,especially the surface within 10 cm,thereby affecting the flood.By analyzing the relationship between the thickness of frozen soil and runoff,we can see that the snowmelt runoff is positively correlated with precipitation,and the thickness of frozen soil is inversely proportional to runoff.It shows that seasonal frozen soil has great effect on the surface runoff of the basin,...