Research On Freeze-thaw Process And Side Oozing Flow Of Snowmelt In The Snow

Arid areas in western China, snowmelt is important freshwater resources. But undercertain conditions it causes huge disasters in the form of snow flood. Carrying outresearches of formation mechanism of the snowmelt runoff will provide an importantbasis for lots of problems, such as flood control, drought and water use, etc. In theseasonal snowmelt period, the complex process of freezing, thawing and migration andflowing of snow melt water in snow cover has been a key and difficult point in thesnowmelt runoff simulation.This article is in the needs of snowmelt flood forecasting, which pointing atpriorities and difficulties of the simulation of snowmelt runoff, though field experimentsand laboratory simulation experiments, starting from a mid-physical point of view, hasdone a more in-depth discussion with freezing and thawing process, and lateral migrationof the law and flowconditions of Snow ablation of snowmelt in the snow in the study areaJunTangHu basin. The main work and the results are as follows:(1)In the snow melting period, snow and snowmelt water will show freezing andthawing phenomenon as the temperature difference between day and night, and thetemperature of snow and moisture of snow layer are determine indicators of the state ofthe snow layer (melting or freezing),that is, when the snow layer is in the melt state, thesnow temperature has been maintained at about0°C, and the moisture content of snowlayer is higher(Generally greater than2%); while snow layer is frozen, the snowtemperature generally are negative temperature and moisture content of the snow layer islower(0%-2%).(2) in the process of snow melting, the snow density is closely related to themoisture content of the snow layer, they are more closely related to each other near thebottom of the snow layer in the study area, the correlation coefficient reaches to0.787(α=0.01); moisture of the snow layer is more closely related to its previous two hours ofthe snow temperature, the correlation coefficient up to0.831(α=0.01).It indicates that the moisture content of the snow melt lags behind the snow layer temperature, the time isabout two hours.(3) The lateral migration of the water of snow melt in the snow layers performsmuch and fast at the soil-snow interface, the average velocity is1.94m/h, while at thesnow layer interface, it performs slow, average flow rate is1.32m/h.(In a gradient of15°, the snow depth of30cm of snow cover)(4) Experimental analysis and verification of seasonal snow ablationperiod,Shallow(10-20cm) soil temperature of covering of snow lags behind the temperature changeabout3.5hours.(5)In the center of experimental field in the study area, the outflow condition thatinferred by the condition of the underlying surface of the experimental quadrates is thatthe average moisture content of the snow layer reaches about8.6484%.(6) At the same conditions, the deeper of the snow, the stronger of its water holdingcapacity, the slower of its outflow; the greater of the slope, the weaker of the waterholding capacity of the snow, the faster of the outflow. The influence of the snow depthdifferences to the moisture content of the snow layer of snow flows is increasinglyweaker with the increasing slope; while the influence of the slope differences to themoisture content of the snow layer when snow flows is increasingly stronger with theincreasing snow depth.(7) Solar radiation is the main energy source for snow melting, respectively, themoisture content of the snow layer, snow temperature, air temperature and solar radiationcorrelation analysis, have correlation coefficients were R1=0.530, R2=0.562, R3=0.757(α=0.01), R3> R2> R1shows the response speed of the three solar radiation andalso reflect the amount of solar energy pathway.(8) Ablation early in the snow, the snow depth decrease was mainly due to the age ofthe upper snow smaller snow melting of sinking due to lower snow depth remainedunchanged.