东北黑土区侵蚀沟阴阳坡侵蚀贡献差异研究

Gully erosion is one of the main erosion types in black soil region of Northeast China. In recent years, the accelerated gully erosion represents a serious threat to the sustainable development of food production and security in the black soil region. Topography is the external condition of gully erosion development. The hydrothermal conditions and the soil freeze-thaw intensity is unlike in different aspect conditions, which results in a significant asymmetry in the pattern and intensity of gully erosion between sunny slope and shady slope. Thus, taking the typical gully erosion in black soil region of Northeast China as the research object，this project will accurately quantify the difference of gully erosion between sunny slope and shady slope during the recent ten years by using various remote sensing methods (for example, the low altitude unmanned aerial vehicles, ground photography and three-dimensional laser scanning et al.) , field observation and indoor physical and chemical analysis , GIS spatial analysis functions. This project intends to 1) reveal the dynamic characteristics of gully erosion difference between sunny slope and shady slope at different time scales (erosion stages - annual - decadal); 2) extract the main factors such as the precipitation, air temperature, soil moisture content and bulk density of soil et al. which have important effects on the gully erosion difference during each erosion stage; 3) propose and validate the estimation model of gully erosion difference between sunny slope and shady slope. These works will deepen the understanding on the morphological feature and development mechanism of gully erosion in the sunny slope and shady slope in black soil region, explore the development trends of gully erosion in the future and provide theoretical guidance for gully erosion prevention and eco-environment conservation in black soil region of Northeast China.

沟蚀是东北黑土区最主要的侵蚀类型之一，近年来越演越烈的侵蚀沟问题极大地影响到黑土区粮食生产的可持续发展。受地形的影响，不同坡向上的水热条件及土壤冻融强度存在显著差异，致使阴阳坡的土壤侵蚀方式和强度也存在明显的不对称性。因此，本项目拟以东北黑土区典型侵蚀沟为研究对象，融合低空无人机、地面摄影测量及三维激光扫描等多种遥感手段，结合野外原位观测与室内理化分析，借助GIS空间分析方法对侵蚀沟阴阳坡的侵蚀贡献差异进行精细尺度的（厘米级-毫米级）量化，分析其在不同时间尺度上（年内-年际-十年）的动态演变规律；综合考虑阴阳坡水热状况、土壤条件等因素，识别不同侵蚀期造成侵蚀差异的主控因素，构建侵蚀差异估算模型并进行精度验证。该研究将有助于深化对黑土区侵蚀沟两坡形态特征及其发育机理的认识，更好地把握侵蚀沟未来发展演化趋势，为我国东北黑土区侵蚀沟防治及生态环境建设提供理论支撑。

地形作为侵蚀沟产生的外部条件，是控制侵蚀沟发生及发展的关键因素，在东北典型黑土区不同坡向所导致的侵蚀沟发育存在较大差异。在本项目资助下，选择黑龙江省克山县东大沟为研究区，采用低空无人机、地面摄影测量及三维激光扫描等多种遥感手段，分析了不同时间尺度上侵蚀沟阴阳坡的侵蚀贡献差异演变规律；利用野外原位观测与室内理化分析技术，识别了造成侵蚀差异的主控因素；在此基础上，构建了阴阳坡侵蚀量估算模型。研究结果表明：（1）近十年不同坡向上土壤侵蚀差异显著，阳坡和半阳坡侵蚀、沉积面积均大于阴坡和半阴坡；半阴坡沉积体积虽略低于半阳坡，但比阳坡的沉积量还大；从体积总变化量来看，不同坡向上均以侵蚀为主，其中：阳坡和半阳坡侵蚀体积占全区总侵蚀体积的70%以上。（2）从年际变化来看，除个别年份外，阳坡和半阳坡的侵蚀沉积面积和体积均大于阴坡和半阴坡。不同年份侵蚀沉积总量及平均侵蚀、沉积深度差异较大，这主要受降水量年际差异的影响。侵蚀深度最大值多出现于阳坡或半阳坡，而沉积深度最大值均出现在平地（以沟底为主）上。（3）从不同侵蚀期来看，两个时段内侵蚀沟发生土壤侵蚀的面积均较大，分别占全区总面积的52.85%和55.10%；冻融/融雪侵蚀期发生沉积的面积（占41.18%）远大于降雨侵蚀期（占13.99%），阴坡上土壤侵蚀面积所占比例最大，阳坡占比最小。降雨侵蚀期沟底下切与土壤沉积并存，二者共同作用下沟底仍以沉积为主，两侧沟岸及沟壁上发生土壤侵蚀的面积远大于沉积面积，阳坡和半阳坡尤为显著。（4）土壤湿度、地表温度和12cm处气温是造成阴阳坡侵蚀差异的主控因素。除此之外，对于阳坡来说，坡度的影响也不可忽略。因为阳坡坡度较大，陡坡上降水的冲刷作用更强，一定程度上加剧了土壤侵蚀的发生和发展。本项目的研究成果有助于深化对黑土区侵蚀沟两坡形态特征及其发育机理的认识，为我国东北黑土区侵蚀沟防治及生态环境建设提供理论支撑。