东北黑土低山丘陵区融雪侵蚀机理与过程研究

Melting snow in spring is a universal phenomenon in the world. Snowmelt erosion is serious in the black soil region of Northeast China. In some places, the snowmelt erosion modulus of spring is even greater than the rainstorm erosion modulus of summer and autumn. There is little research on snowmelt erosion mechanism and process in China. This application project will take the the ridge tillage farmland in the Northeast of China as the object of study. At first, through measurement snow thickness, climate condition and slope position in the wild to clarify why the snow accumulation difference in difference places, and how the snow accumulation effected by these factors. And then, through observe the changes of snow nature and the process of snow melt to explain the relationship between snow melting rate and influence factors. Through indoor simulation snowmelt flow production first at upslope and the flow rush to the accumulated snow at down slope, to seek the effect relationship between upslope snowmelt runoff and down slope snow melting rate. On the basis of the above study and combined with the results of previous studies about soil erodibility change effected by freeze and traw, through the experimentation of snowmelt runoff area in the outdoor to thorough understand the snowmelt erosion process in different conditions, and to differentiate snowmelt erosion process from rainfall erosion process. When the process of snowmelt flow production and snowmelt erosion has be known, it will become the important theory foundation for snowmelt erosion forecasting, and snowmelt erosion control in China.

春季融雪是世界上许多国家普遍存在的现象，我国东北黑土区春季融雪侵蚀严重，部分区域甚至超过夏秋季暴雨侵蚀程度。目前，我国对于融雪侵蚀机理与过程研究尚不多见。本申请项目以东北黑土低山丘陵区为研究对象，首先在室外通过实测融雪前坡面积雪分布情况，阐明气候、土地利用、坡位等因素对降雪累积的影响；通过观测室外不同条件下积雪融化与产流进程，以及室内模拟上坡融雪径流优先产生条件下，上坡融雪径流对加速下坡积雪融化的影响，明确坡面融雪侵蚀动力机制；通过观测表土含水量寒季变化过程，结合以往研究成果，揭示冻融作用等因素影响条件下融雪期表土抗蚀性变化特征。在以上研究基础上，通过室外坡面径流小区试验，深入了解春季解冻期融雪径流、表层土壤可蚀性降低与表层解冻土壤下未完全解冻层等多重因素作用下，融雪径流有别于降雨径流较为独特的侵蚀过程。对融雪侵蚀机理与过程的掌握，将为我国融雪侵蚀的预报与防治奠定重要的理论基础。

春季融雪是世界上许多国家普遍存在的现象，我国东北黑土区春季融雪侵蚀严重，部分区域甚至超过夏秋季暴雨侵蚀程度。目前，我国对于融雪侵蚀机理与过程研究较少。本研究以东北黑土低山丘陵区为研究对象，首先通过分析黑土区气温、辐射、降雪等气象资料，以及在野外通过实测融雪前坡面积雪特征与环境情况，阐明了气候、土地利用、坡位等因素对降雪累积的影响，明确了黑土区降雪和积雪在宏观尺度及坡面尺度的分布特点，确定了黑土区降雪集中区域和融雪侵蚀易发区；通过观测室外不同条件下积雪融化与产流进程，以及室内模拟上坡融雪径流优先产生条件下，上坡融雪径流对加速下坡积雪融化的影响，阐明了坡面积雪融化机制，以及积雪融化主要影响因素与融雪径流间的定量关系，进而明确了坡面融雪侵蚀动力机制；通过野外观测表土含水量寒季变化过程，结合以往研究成果，阐明了土地利用、土壤性质、地貌特征等因素对冻结期表土水分变化的影响关系，以及黑土区寒季表土水分空间变化特点，揭示了冻融作用等因素影响条件下融雪期表土抗蚀性变化特征。在以上研究基础上，通过室外坡面径流小区试验及坡面集水区观测试验，阐明了黑土区垄作农田坡面融雪产汇流机制及坡面融雪侵蚀机制，深入了解了黑土区春季解冻期融雪径流、表层土壤可蚀性降低、表层解冻土壤下未完全解冻层等多重因素作用下，融雪径流有别于降雨径流较为独特的产汇流与侵蚀过程。对比分析了垄作农田坡面融雪侵蚀与一般降雨侵蚀在侵蚀机理与侵蚀形式上的异同表现，明确了黑土区典型土地利用及水土保持措施对降雪累积、融雪产流及融雪侵蚀的不同影响关系。对融雪侵蚀机理与过程的掌握，将为我国融雪侵蚀的预报与防治奠定重要的理论基础。