| Dongzhi tableland is the most complete and largest loess plateau in the loess highland area,and has the reputation of "the First Plateau in the World" and "Long Dong Granary".Since the establishment of the Xi Feng Soil and Water Conservation Experimental Station of the Yellow River Committee in the 1950 s,it has consistently adhered to the scientific experiment of soil and water conservation and the practice of comprehensive treatment of highland surface,summed up the highland surface prevention and control model,which has played a certain role in controlling soil erosion and protecting ecology.With the implementation of the large-scale conversion of farmland to forests,the vegetation around the plateau has undergone tremendous changes.In addition to the increase in the urbanization development and the number of various construction projects in the plateau area in recent years,the erosive environment has been fundamentally improved and needs to be refined and summarize the comprehensive management model of soil and water conservation under the new situation.Therefore,this study takes Dongzhi tableland’s comprehensive protection measures system as the research object,based on the theories of soil erosion,soil and water conservation,soil and water conservation engineering,and soil and water conservation forestry,and uses a combination of field investigation and theoretical analysis to analyze.At this stage,the main hazards of the traceability erosion in the gully area of the plateau area,the causes of the traceability erosion,the current main technical system and model of the traceability erosion control in the gully area of the plateau area,and the problems existing in the governance.The design and construction of the follow-up implementation plan for the protection of the loess plateau in the district will provide useful reference for improving the comprehensive management model of "Gu Gou Bao Yuan",promoting poverty alleviation,and achieving sustainable economic and social development.The main conclusions are as follows:1.The occurrence of traceable erosion is the result of the interaction between natural and human factors.The difference of terrains between tableland and gully,the short-time heavy rain and the low vegetation cover were the main natural factors that induced the tractive erosion.The urbanization construction,unreasonable project site selection and concentrated flood discharge in urban areas were the main human factors inducing the traceable erosion of tableland.The main harm of traceable erosion is: destroying traffic routes,encroaching farmland and threatening people’s life and property safety.2.Based on a large number of field investigations and in combination with the regulation and utilization methods of tableland runoff,the existing gully head management modes in Dongzhi tableland were summarized into the following three categories: 1)"impound-type" gully head management modes,which mainly included "wai terrier forest belt" and "wai terrier log pond";2)"drainage type" groove head governance mode,which mainly includes three types: "flow carrying and energy dissipation type","slope straight row type" and "concealed pipe flow diversion type";3)the two types of trench head protection measures,"backfill and reinforcement type" and "slope cutting and grading type",are often used together with the above treatment mode.3.Based on a large amount of field investigation and evidence collection,the problems existing in the treatment of gully head in dongzhi tableland were summarized into the following three aspects: 1)the vegetation recovery of gully head was slow after treatment,and there was a potential risk of traceability;2)the layout and design of protection measures for some trench heads are not reasonable,and it is easy to trace the source under extreme rainstorm conditions;3)surface erosion and trench erosion will still occur after the treatment of gully head.4.It is possible to promote the restoration of the gully head vegetation by means of guest soil covering,tilling and loosing,planting pioneer plant species,and strengthening human control.The protection measures for the gully head should be based on the local heavy rain in 10a～15a as the design standard,and at the same time take into account the area of the catchment area,terrain and land use;the gully head protection project must be combined with the gully control measures(Gufang,silt dam,etc.);before the arrival of the flood season each year,the trench head protection project should be repaired to ensure that it can play a normal role in flood control;the flood protection period or after the end of the rainstorm should be timely repaired and maintained. |
