典型黑土区不同尺度沟蚀演化过程及效应研究

发布时间：2018-02-09 06:28

本文关键词： 黑土区沟蚀演化过程地面立体摄影测量 AnnAGNPS 遥感　出处：《中国科学院研究生院(东北地理与农业生态研究所)》2016年博士论文　论文类型：学位论文

【摘要】：研究黑土区不同类型坡耕地沟蚀演化过程及效应对侵蚀沟防治具有重要的意义。受限于已有研究基础及数据获取方法,目前关于黑土区沟蚀演化过程的研究薄弱。因此,本文以黑土区坡耕地细沟、浅沟及切沟为研究对象,采用遥感影像与沟蚀模型相结合的方法,并结合自行发明的立体摄影测量监测细沟发育过程的实验方案,建立了适宜于野外径流小区监测细沟侵蚀过程的方法,评价了模型模拟浅沟发育过程的优缺点,研究了黑土区坡耕地细沟、浅沟及切沟等不同尺度侵蚀沟的空间演化过程,并结合农业生产实际情况,评价了沟蚀危害及相应防治措施的经济效益。主要结论如下:(1)基于自行研制的地面立体摄影技术监测坡面小区尺度细沟侵蚀发育过程的实施方案,初步研究了坡面细沟侵蚀发育过程。该方案能够获取坡面尺度的次降雨径流侵蚀及融雪侵蚀导致的细沟发育过程的数字地面模型数据,具有成本低、快速、精度高、非直接接触,易操作,适宜于多种立地条件,且可长历时动态观测的优点。该方法获取的侵蚀量与实测侵蚀量的误差为50%,基本满足精度要求。基于该方法获取了2015年度降雨径流侵蚀下的细沟侵蚀发育过程。随着降雨次数的增多,坡面的微地形起伏降低,坡面变平滑,坡面变异系数由57%下降为53%;但坡面侵蚀深度与沉积厚度均加强,侵蚀深度增大了7 mm,而沉积深度增大了11 mm。同时坡面线状水流的密度降低,但形成了主水流,袭夺周围细小水流,宽度增大;在主水流的基础上形成细沟。坡脚处首先形成细沟,细沟溯源侵蚀逐渐向坡中上部发展。雨季前期细沟侵蚀主要过程为沟底下切与溯源侵蚀;而在雨季后期主要过程为细沟增宽。(2)基于AnnAGNPS模型模拟了坡耕地浅沟发育过程及经济损失。敏感性分析显示该模型模拟浅沟发育过程的主要误差来源是沟头侵蚀系数(HDC)。假设用以填埋浅沟的区域宽度为5 m,则该区域每年因填埋浅沟而造成的浅沟周围耕层厚度下降速度约为1 cm y-1。结合作物产量与耕层厚度关系式,计算出因填埋浅沟而耕层厚度下降导致的经济损失年均值为$11 hm-2y-1。当在浅沟区域布设草筏子时,作物产量下降的成本加上草筏子的建筑成本之和是浅沟侵蚀造成产量下降经济损失的170倍。故因此从经济方面考虑,在缺乏外来资金投入或政策支持情形下,农民对布设沟蚀防治措施的自发主动性不高。(3)基于1968年与2009年的亚米级遥感影像分析了典型黑土区切沟演化过程及影响因素。截至1968年,该区域切沟侵蚀已经度过了初期的沟长迅速发展的阶段。2009年侵蚀沟的基本分布在1968年已经形成。从1968年起主要的沟蚀发展过程是侵蚀沟的合并与沟宽的发展。简单沟与复杂沟的平均流域坡度值的范围近似,但复杂沟的平均流域面积远大于简单沟,表明相对于流域平均坡度,流域面积对侵蚀沟发育的影响更大。流域面积与平均坡度对侵蚀沟发育的协同作用使得在研究侵蚀沟发育时要同时考虑二者。在本区域简单沟与复杂沟的流域面积阈值约为15-25 hm2。该阈值能够预测在相似的环境条件下,在给定的流域中能够发育的侵蚀沟类型。由于侵蚀沟的深度过大,因此在该区域实施退耕还林很难有效的治理侵蚀的发展,应当采取恰当的工程措施。此外由于新成沟占所有侵蚀沟的面积仅为7%,因此如果新成沟的发展为目前保留沟的大小,侵蚀沟危害将会翻倍。
[Abstract]:Study on different types of Sloping Farmland in black soil area of gully erosion evolution process and effect has important significance to the prevention of erosion ditch acquisition method. On the foundation of the research and the limitation of the existing data, the current research on the evolution of the black soil area of gully erosion is weak. Therefore, the rill slope farmland, shallow gully and gully as the research object, method using remote sensing image and gully erosion model combined with the experimental scheme, combined with stereo photogrammetry monitoring rill self invented development process, established a suitable method for monitoring field runoff plots of rill erosion process, the advantages and disadvantages of the evaluation model for shallow gully development process of rill, sloping farmland in the black soil region, the process of evolution shallow ditch and gully erosion in different scale, combined with the actual situation of agricultural production, assessment of gully erosion hazards and prevention measures of economic benefits. The main conclusions are as follows: (1) base In the implementation plan developed by the ground stereo technology monitoring plot scale slope rill erosion development process, a preliminary study of rill erosion development process. This scheme can obtain the slope scale development of rainfall runoff erosion and rill erosion caused by snowmelt DTM data, has the advantages of low cost, fast, high precision, non direct contact, easy to operate, suitable for a variety of site conditions, and long duration dynamic observation and measure error. The advantages of this method for erosion erosion is 50%, basically meet the accuracy requirements. Based on the method of obtaining the 2015 annual rainfall runoff erosion and rill erosion under the process of development. With the increasing of rainfall frequency. To reduce the micro topography slope, slope smooth slope, the coefficient of variation decreased from 57% to 53%; but the erosion depth and thickness are strengthened, the erosion depth. The 7 mm, and the deposition depth increased by 11 mm. and the linear flow density decreased slope, but the formation of the main flow, capture all the small flow, increasing the width of rill formation; based on the main flow. The toe first formed rill rill, headward erosion gradually to the upper slope. The rill erosion mainly early rainy season the process for the ditch bottom cutting and headward erosion; while in the main process for rill late rainy season widened. (2) AnnAGNPS model to simulate the development process and the economic loss of shallow gully slope land. Based on the sensitivity analysis showed that the main error sources of the model to simulate the shallow gully development process is gully head erosion coefficient (HDC) hypothesis to. The width of the shallow trench landfill area is 5 m, around the area of topsoil thickness shallow trench landfill each year due to shallow gully caused by the decline in the rate of about 1 cm y-1. combined with the relationship between crop yield and soil thickness, calculated for shallow trench landfill The topsoil thickness average annual economic losses led to a decline in value of $11 hm-2y-1. in the shallow gully region when the grass raft layout, the construction cost of declining crop yields cost plus grass raft and is caused by 170 times the yield decreased economic losses. Therefore the ephemeral gully erosion from the economic considerations, in the absence of external funding or policy to support the case, farmers on layout of gully control measures initiative is not high. (3) submeter remote sensing images in 1968 and 2009 based on the analysis of the typical black soil region gully evolution process and influencing factors. As of 1968, the area of gully erosion has passed the basic distribution of the initial channel length of a stage of rapid development.2009 years of gully erosion has been formed in 1968. From 1968 onwards the main gully erosion development process is combined with the width of the ditch erosion gully development. The average range of slope gully and gully basin simple complex value near Like, but the average area is far greater than the simple complex basin ditch ditch, compared with the average watershed slope, watershed area has more influence on gully development. The basin area and average slope of gully development due to the synergistic effect in the study of gully development should be taken into account when the two. In the area of simple ditch and drainage area the complex channel threshold is about 15-25 hm2. the threshold can be predicted in similar condition to erosion gully development in a given basin. Due to erosion gully erosion depth is too large, so the development of governance in the region of returning farmland to forest is difficult to have the effect, should adopt suitable engineering measures. In addition, since the new channel accounted for all the gully area is only 7%, so if the new channel for the development of the current reserve groove size, gully erosion hazards will be doubled.

【学位授予单位】：中国科学院研究生院(东北地理与农业生态研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S157

【参考文献】