| Snowfall on the northern slope of the Tianshan Mountains is a seasonal snowfall,and the runoff from spring snow melting is an important source of recharge for the surrounding rivers.Aiming at the study of snow melting process on the northern slope of Tianshan Mountain,most of them focus on the analysis of the effects of solar radiation,temperature,slope,aspect and other factors on the snowmelt process,and analyze the snow ablation process under different underlying conditions.Therefore,the research is small.Therefore,baseing on the Tianshan Forest Ecological Positioning Station,this paper selects the typical area(same elevation,same slope)of the station to set up the forest,grassland and bare ground fixed observation plots to monitor the whole snow ablation process.According to many years of statistical data,this paper divides the entire snow ablation process into snow cover period(2017.11-2018.2)and snowmelt period(2018.3-2018.4),during snow cover and snowmelt period.The data of forest land,grassland and bare land snow were collected separately.The differences of snow surface characteristics and the correlation between meteorological factors and soil factors were analyzed by combining meteorological factors and soil factors.The preliminary study on the ablation process of snow under different underlying conditions on the northern slope of Tianshan Mountain is to provide basic data for the snow ablation process of different underlying areas on the northern slope of Tianshan Mountain.The main conclusions are as follows:(1)Snow characteristics during snow cover: The snow cover(13.86 cm),bare land(32.10 cm)and grassland(36.31 cm)increase in turn,and the minimum snow cover depth is mainly due to the interception effect of forest canopy on snowfall.The interception amount is about 45.33%;the snow cover,grassland,bare ground snow density and liquid water content are the largest at 0 cm-5 cm of the bottom layer of the snow layer;the liquid water content of the forest land(0.51%)is larger than the bare land(0.33%)and grassland(0.30%);bare land(0.202 g/cm3)has the highest snow density,followed by grassland(0.167 g/cm3),woodland(0.159 g/cm3);woodland(-4.60 °C)snow layer The temperature is the smallest,the temperature of bare snow layer is the largest(-3.77 °C);the density of snow in the bare snow,the depth of snow and the temperature of the snow layer are significantly negatively correlated;the liquid water content of snow in forest,grassland and bare ground and The temperature of the snow layer is highly positively correlated,and the degree of correlation is ranked as: bare land> grassland> forest land.(2)Snow characteristics during snowmelt period: The snow cover depth during the snowmelt period has the highest rate of decline with time,and the snow cover depth is the smallest(8.06 cm);the snow cover liquid moisture content(0.61%)and the snow cover density(0.484 g/ Cm3)is greater than grassland and bare land;the temperature of snow layer in forest land,grassland and bare land is-0.03 °C,0.05 °C,and 0.14 °C,respectively;the depth of bare snow is significantly negatively correlated with snow temperature(r=-0.946,P <0.05);the snow density and the water content of the bare land were significantly positively correlated;the snow depth of the grassland was significantly correlated with the snow density(r=0.756,P<0.05).(3)Characteristics of runoff during snowmelt period: the earliest production of bare land began,followed by forest land and grassland;the days of continuous runoff of forest land,grassland and bare land were 5 days,8 days,5 days respectively;bare land flow(314.44 kg)The maximum is twice the grassland(153.39 kg),which is6 times that of the forest land(50.66 kg);the erosion amount of the forest land,grassland and bare land on the surface during the snowmelt period is 20.7g,103.8g,508.7g,respectively,accounting for the total runoff.The ratio is 0.025%,0.067%,and0.193%,and the forest,grassland,and bare land flow rates are the fastest in the period of 13:00-15:00,and the production flow rate is the largest.(4)Correlation between snow characteristics and meteorological factors:There is a significant negative correlation between solar radiation,temperature and bare snow depth during snow deposition,and a significant positive correlation with bare snow density;temperature and bare ground snow temperature are extremely significant.Correlation(r=0.992,p<0.01);temperature was significantly positively correlated with forest snow density and grassland liquid water content.There was a significant negative correlation between snow depth and solar radiation during snowmelt(r=-0.960,p<0.01);snow density was positively correlated with solar radiation(r=0.908,p<0.05);bare snow density There was a significant positive correlation between liquid water content,snow layer temperature and temperature;the runoff generated by grassland snow was significantly positively correlated with atmospheric temperature(r=0.803,p<0.05),bare ground runoff and temperature,sun There was a significant positive correlation between the radiation.(5)Correlation between snow characteristics and soil factors: The soil layer temperature at 30 cm is positively correlated with the snow cover liquid moisture content and snow layer temperature in forest land and bare land;the soil layer temperature and bare ground runoff at 40 cm(p<0.01,r=0.983),both Significantly positive correlation.The soil moisture content at 10 cm during the snowmelt period was significantly positively correlated with the snow density of forest land,grassland and bare land.The soil moisture content at 20 cm was significantly positively correlated with the runoff of grassland and bare land,and the liquid water content of bare land was also There was a significant positive correlation;the soil moisture content at 30 cm was significantly negatively correlated with the snow depth of the grassland,and was positively correlated with the liquid water content of the grassland and the runoff of the bare land;the soil layer temperature at 10 cm and the snow density and grassland product of the forest land.The positive correlation of snow production was high,and it was significantly negatively correlated with bare snow depth(r=-0.955,p<0.05).The soil temperature at 30 cm was significantly negatively correlated with grass depth,and was significantly correlated with snow density.Positive correlation. |
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