大兴安岭北部森林小流域融雪径流特征

为了揭示森林小流域融雪径流特征及其影响因素,以大兴安岭北部老爷岭小流域为研究对象,对初春融雪径流进行野外定位观测,基于试验观测数据分析了融雪径流的变化特征,以及温度、降雨和冻土对融雪径流的影响。结果表明:2015年大兴安岭北部森林小流域融雪径流开始于4月17日,结束于5月7日,融雪径流历时21 d; 整个融雪径流过程呈先涨流、后回落、再稳定3个阶段,径流量介于0.08～1.09 m³/s; 5月11日后径流趋于稳定,径流量波动于0.46 m³/s。融雪径流前期和后期日径流存在明显昼夜流量差,而洪峰期差异不大,洪峰流量可持续24 h左右。融雪径流过程径流量受多重因子的影响,其中受温度影响较大,二者相关系数r在0.85以上; 径流量对气温的敏感性最大,敏感系数ε高达0.54; 土表的融化会相应加大融雪径流量,而下层土壤的融化会削减融雪径流量; 降雨可加大涨流期的径流量,延缓回落期径流量的回落速率,且降雨量越大对径流量的驱动力越强。

Forming process of snowmelt-runoff of forest watershed in northern region of Da Hinggan Mountains

In order to reveal the characteristics of snowmelt-runoff and its influencing factors, a watershed at the Laoye Mountains in northern region of Da Hinggan Mountains was selected as an experimental object. Based on the experimental data, the characteristics of snowmelt-runoff were analyzed and it was found that three major affecting factors, such as temperature, rainfall and frozen-soil, were essential to snowmelt-runoff. The following conclusions were reached: snowmelt-runoff began on April 17 and ended on May 7 in the forest watershed in 2015. The process of snowmelt-runoff lasted for 21 days,the whole process of snowmelt-runoff had three different stages which were flood-stage, peak-stage and back-stage respectively. A mount of snowmelt-runoff fluctuated from 0.08 m³/s to 1.09 m³/s. After the May 11, snowmelt-runoff tended to 0.46 m³/s. Snowmelt-runoff had obvious difference of temperature between day and night in the early stage and later stage. However, the difference in peak-stage was not significant. The peak-runoff can be sustained and stable around 24 h. Snowmelt-runoff were significantly influenced by many factors especially temperature. The correlation coefficient between snowmelt-runoff and temperature was above 0.85, and the runoff was more sensitive to temperature than to other factors. The sensitive coefficient was up to 0.54. The melting of soil surface would increase the snowmelt-runoff,however,the melting of the soil below the surface would reduce the snowmelt-runoff. Rainfall can increase runoff in the flood-period, slow down drop-rate of runoff in the back-period. And the more rainfall, the greater driving-force.