| The geographical distribution of China’s power resource production shows the characteristics of more in the West and less in the East,while the distribution of power demand is opposite.With the rapid development of the national economy,the imbalance between supply and demand is becoming more and more prominent.The optimal allocation and transmission of electric energy across the country is imminent,and the construction of large-scale transmission line projects is urgent.However,the construction of transmission line project will inevitably change the landform around the construction area and damage the surface vegetation and disturbed soil layer.If it is not protected and treated in time,it is very easy to lead to serious soil and water loss.At the same time,due to the special location of the soil and water loss part of the transmission line project and the difficulty of soil and water loss control,the problem of soil and water conservation of the transmission line project is becoming more and more prominent,and it is urgent to study the control measures and system.Therefore,this study takes the transmission line in hilly area as the research object,combines field investigation and theoretical analysis,studies the soil and water loss status and soil and water conservation measures of the transmission line project in typical hilly areas in northwest loess hilly area,Qinghai Tibet Plateau,southern red soil hilly area,Northeast low mountain and Mangang hilly area and Xinjiang mountain area,and combines the existing comprehensive treatment technical measures,designs a set of regional and differentiated soil and water loss control technology system suitable for the control of transmission line projects in hilly areas throughout the country.This research can enrich the development connotation of soil and water conservation discipline of development and construction projects,provide theoretical basis and technical support for soil and water conservation of transmission lines in hilly areas,and provide reference value for comprehensive treatment of soil and water loss of transmission line production and construction projects in hilly areas throughout the country.The main conclusions are as follows:（1）This paper investigates the current situation of water loss and treatment of transmission line projects in hilly areas,combs and summarizes the main links of water and soil loss caused by line construction and the main difficulties faced by the comprehensive treatment of water and soil loss of transmission line projects.The main links of water and soil loss easily caused by transmission line construction include:1)the earth is not covered in time after excavation;2)The temporary retaining measures in the soil stacking area are not in place;3)Disturbance of vehicle to road area;4)Unreasonable stacking of building materials and no surface covering protection;5)Disturbance and damage of large equipment to the surface during setting out construction.In terms of governance,generally speaking,although the zoning governance of transmission line engineering has been widely used,the actual governance effect is not very ideal.At present,the main difficulties faced by the comprehensive control of soil and water loss in transmission line projects include:1)long construction lines,complex prevention and control zoning,and lack of unified and standardized measures;2)Inadequate prevention and restoration measures for soil and water loss on construction roads;3)It is difficult to restore vegetation in foundation of tower.（2）The soil erosion intensity produced by the construction of transmission line engineering in the hilly area is measured and calculated.The soil erosion intensity produced between the types of hilly areas and between the erosion units has an obvious size law.The results show that:1)under the condition of similar construction technology,the difference of soil erosion intensity caused by transmission line construction in hilly area is determined by the difference of soil erosion influence factor level between regions.During the construction period,the highest soil erosion modulus is produced in the Loess Hilly Region of Northwest China(13268.06 t·km-2·a-1),followed by the red soil hilly region of South China(7432.98t·km-2·a-1),Xinjiang mountain region(5317.65 t·km-2·a-1),northeast low mountain and Mangang hilly region(4617.28 t·km-2·a-1),and the lowest value is produced in Qinghai Tibet Plateau Region(3698.43 t·km-2·a-1).In the natural recovery period,the order of this value from large to small is northwest loess hilly area(7813.27 t·km-2·a-1)>Xinjiang mountain area(2341.15 t·km-2·a-1)>Northeast low mountain and Mangang hilly area(2075.35 t·km-2·a-1)>Qinghai Tibet plateau area(1934.52 t·km-2·a-1)>Southern red soil hilly area(1425.04 t·km-2·a-1).At the same time,in terms of the soil erosion modulus produced by the four types of erosion units of the project,the numerical order in each period is also consistent with the average soil erosion modulus produced by the project as a whole;2)In the construction area of transmission line project in single type hilly area,the order of soil erosion modulus generated in four types of erosion units during construction period and natural recovery period is maintained as tower foundation area>Road area>traction site area>crossing site area.3)The order of soil erosion amount produced by the construction of transmission line project per unit length in each period of four types of hilly areas is consistent with the order of erosion modulus produced by the whole project in each period.（3）The comprehensive control measures for water and soil loss of transmission line projects in different types of hilly areas shall be designed differently according to the characteristics of water and soil loss in each area.The difference of soil and water loss characteristics of transmission lines in various hilly areas determines that the existing measure design should not be simply applied in its comprehensive treatment,but the engineering measures,plant measures and temporary measures in different types of hilly areas should be designed differently according to the comprehensive treatment measure system of soil and water loss applicable to transmission line projects in different types of hilly areas,and draw lessons from the typical design results of differential layout in this paper.（4）The 750kV Pingliang substation 330kV shangjiayuan 330kV line project 76#and 80#tower foundation and surrounding road area in Gansu Province are selected as the test area to verify the applicability of the designed comprehensive treatment measure system.Through the layout of practical measures and water and soil loss monitoring,in terms of vegetation restoration,the vegetation coverage in most areas has reached more than 75%.From the perspective of soil erosion modulus,after treatment,the soil erosion intensity in the two areas has been reduced by 63%and 67%respectively compared with the construction period,and the water and soil loss in the area has been effectively improved. |
