Research On Drainage Contour Profile Enforcement Of Altered Ditches Based On Uav-derived Digital Elevation Model

Irrigation canal is the most important water conservancy facilities in Hetao Irrigation District.Using for the transmission and distribution of water between a reservoir and a farmland,then irrigating the crops.It is very important to master the distribution information of drainage system to improve the efficiency of agricultural water distribution,real-time monitoring of irrigation water and irrigation decision management.Therefore,the extraction of digital canal is particularly important.However,in the extraction of the drainage system,the effect will be influenced by the factors of the channel in the depression,the bridge on the channel,culverts and other natural or human terrain.In this paper,the Digital Elevation Model obtained from the ortho-imaging of UAV aerial photographies was taken as the research area in the area of Haifeng County in Hetao area.We used the Stream Burning algorithm and the improved Least Cost Path-based breaching algorithm to remove depression in the channel,bridges,culverts and underpass on the channel,so that the drainage characteristics can be enhanced.Then the DEM information of the drainage system was supplemented by the spectral information of the canal system as the classification feature,and the classification of the canal system based on the positive and unlabeled single classifier of the random forest was used to obtain the canal system Enhanced effect.The main contents and results of this paper are as follows:(1)Selecting the appropriate burning depth and attenuation coefficient,then calculating the elevation of the grid corresponding to the canal system,replacing the original elevation value by using the Stream Burning algorithm to enhance the drainage characteristics with the part of the canal vector information as auxiliary data.The experimental results showed that the integrity and accuracy is71.9% and 72.5%,this method can enhance the drainage characteristics.(2)Improving the depression breaching algorithm,selected the breach path and the target grid with the least cost path to enhance the characteristics of the ditch and removed the influence of the channel in the depression,channel on the bridge,culverts,underground canal and other artificial landscapes,making the drainage system in the high-resolution DEM more obvious,characteristics of the continuity and smoothness of the canal system more better.The results of the enhancement result showed that 93.8% of the depressions were effectively treated after the enhanced DEM,and the integrity and accuracy is increased dy 10.9% and 11.1%.(3)The LCP algorithm was compared with the depression,the depression and the channel burning algorithm respectively.The experimental results showed that the LCP algorithm used in this paper has a good result on abrupt topography,such as bridge and culvert,the integrity and accuracy of the drainage system is 72.5% and 70.6% respectively,which was stronger than that of the depression.Compared with the stream burning enhancement algorithm,LCP algorithm did not need auxiliary data such as ditch vector,and the processing efficiency was higher.Besides the improved depression breaching algorithm can remove the natural or man-made landforms in the depressions,trenches and culverts in the channel,and effectively enhanced the drainage characteristics.