利用虚拟插钎对切沟沟底不同部位短期变化的初步研究

插钎法是研究侵蚀的常用方法,但精度不高且易受人为因素影响。文章探讨以虚拟插钎点代替实物插钎的可行性,并对黑龙江鹤北小流域的一条切沟沟底高程的年际变化进行研究。对研究所需的DEM精度进行检验,其能达到cm级,满足研究需求。研究发现,切沟头部为沟底下切最剧烈的区域,而在降雨偏少的年份,主要的堆积区域在切沟的中上部和中下部,沟尾部无论降雨强弱,变化最细微。

Short-term Gully Erosion at Different Places of Bottom of Gully Using Virtual Erosion Pins

Erosion pins is widely used to measure the wind and water erosion, but the accuracy of this method is relatively low because this method is usually impacted by human activities. The black soil region in Northeast China is suffering from soil erosion due to intense reclamation in the middle of 20 century, and gully erosion in this region is very severe. However, the previous researches were mainly focused on the changes of the entire gully. It is difficult to monitor the changes at a certain site inside the gully and few research were focused on this problem. In this paper, we try to use the GIS points as the virtual erosion pins instead of the real erosion pins to monitor the erosion and deposition process at the bottom of gully in Hebei catchment in Heilongjiang Province. Virtual erosion pins were not affected by the environment, human activity and ground settlement. The precision of the gully’s DEM can reach the cm-level examined by the checkpoint method, which was used to this research. The annual variation of the bottom of gully monitored by the virtual erosion pins combining with the high precision gully DEM consist with the regular gully development by the previous study. The results prove that using virtual erosion pins combining with high precision DEM to monitor the annual variation of gully bottom is valid. From the DEM we found that the head part of the gully incised intensely. The mid-part is the main place of the deposition in the dry years, and the incision is relatively weaker than the head part of the gully at the wet years, because the runoff’s sediment transport capacity reaches the saturation level while the flow velocity decreases due to the increasing width of the gully. The end of the gully is relatively stable because the runoff and sediment has reached a relative equilibrium state.