CN111919630B

CN111919630B - Vegetation construction method for reducing soil erosion of trench wall in loess area

Info

Publication number: CN111919630B
Application number: CN202010684969.0A
Authority: CN
Inventors: 任宗萍; 王凯博; 高海东; 谢梦瑶; 周壮壮; 张星; 马晓妮
Original assignee: Xian University of Technology
Current assignee: Xian University of Technology
Priority date: 2020-07-16
Filing date: 2020-07-16
Publication date: 2022-04-15
Anticipated expiration: 2040-07-16
Also published as: CN111919630A

Abstract

The invention discloses a vegetation construction method for reducing soil erosion of a trench wall of a loess area, which comprises the following steps of 1, surveying slope land conditions for vegetation construction; step 2, according to the survey result of the slope surface land conditions in the step 1, selecting plant varieties planted in different land conditions of the loess plateau; step 3, selecting seeds and nursery stocks of the plant variety screened in the step 2; step 4, carrying out slope land finishing; step 5, designing a slope surface intercepting ditch on the slope surface land finished in the step 4; and 6, planting the seeds and seedlings screened in the step 3 on the slope land of the intercepting ditch designed in the step 5. The invention effectively reduces the soil erosion of the trench wall by reducing the runoff water inflow of the slope and changing the flow path, and provides technical support for regional water and soil loss treatment and ecological civilization construction.

Description

Vegetation construction method for reducing soil erosion of trench wall in loess area

Technical Field

The invention belongs to the technical field of water and soil conservation engineering, and relates to a vegetation construction method for reducing soil erosion of a trench wall in a loess area.

Background

The loess plateau is the most serious region of water and soil loss in China and even the world, and is also the key region of water and soil conservation and ecological restoration. In order to prevent water and soil loss of loess plateau and improve ecological environment and people's life in the area, loess plateau is subjected to a plurality of treatment stages of slope treatment, ditch and slope combined treatment, small watershed comprehensive treatment, returning to farming and forests (grass) and the like from the beginning of the country. After more than 70 years of scientific treatment and comprehensive prevention, the water and soil conservation measure area of the loess plateau area reaches 21.3 km²And approximately half of the water and soil loss area of the area is primarily treated. The vegetation coverage of the loess plateau is increased by less than 20 percent in the last 80 yearsBy the current 63%, the amount of sand in yellow mud has dropped from 13 hundred million tons/year in the 70's of the 20 th century to less than 3 hundred million tons/year in the present.

Although the water and soil loss of loess plateau is primarily restrained and the ecological environment is obviously improved, the risk of soil erosion in the area is still large due to loose porosity of loess structure, fragmentation of regional terrain, concentration of rainfall time and the like, and the sand yield of the area under extreme rainstorm conditions can still exceed 10 hundred million tons. Research shows that the erosion silt of loess plateau areas mainly comes from valley lands, and the erosion of the trench walls usually accounts for more than 60% of the total erosion amount of a drainage basin. And along with the restoration of the vegetation on the slope, the sand content of the runoff on the slope is reduced, the runoff sand-carrying capacity is further enhanced, and the erosion risk of the ditch wall of the drainage basin is aggravated. Therefore, how to reduce the soil erosion of the trench wall in the loess region and further reduce the water and soil loss in the region is one of the bottleneck problems in the current loess plateau water and soil loss treatment which needs to be overcome urgently.

The vegetation construction is an important way for the water and soil loss control of the loess plateau. The vegetation is trapped and dammed the runoff through the canopy, and the rainfall infiltration is increased; the raindrop kinetic energy is dissipated through root system consolidation, soil structure improvement and other modes, the regulation and storage capacity of the soil reservoir is improved, and the impact resistance of the soil body is enhanced, so that the effects of preventing and treating soil erosion and reducing water and soil loss are achieved. The existing water and soil conservation vegetation construction of the loess plateau mainly adopts a mode of planting trees and grass on a ditch slope, and reduces the slope soil erosion by improving the vegetation coverage. Although the slope soil erosion is obviously reduced along with the increase of the vegetation coverage, the erosion amount of the trench wall is invisibly increased due to the influence that the slope runoff sand content is reduced and the sand-carrying capacity is enhanced after the vegetation is increased. The walls of the furrows are positioned in the furrows and valleys below the side lines of the loess hills, the slopes are large, the loess is exposed, and the treatment difficulty is high. The trench wall soil erosion is an important source of the current loess plateau water and soil loss, the effective prevention and control of the trench wall soil erosion is a key link for the successful treatment of the loess plateau water and soil loss, and the method has important significance for regional ecological civilization construction.

Disclosure of Invention

The invention aims to provide a vegetation construction method for reducing the soil erosion of the trench wall of a loess area.

The invention adopts the technical scheme that a vegetation construction method for reducing the soil erosion of the trench wall of a loess area specifically comprises the following steps:

step 1, surveying the slope surface ground conditions for vegetation construction;

step 2, according to the survey result of the slope surface land conditions in the step 1, selecting plant varieties planted in different land conditions of the loess plateau;

step 3, selecting seeds and nursery stocks of the plant variety screened in the step 2;

step 4, carrying out slope land finishing;

step 5, designing a slope surface intercepting ditch on the slope surface land finished in the step 4;

and 6, planting the seeds and seedlings screened in the step 3 on the slope land of the intercepting ditch designed in the step 5.

The present invention is also characterized in that,

the survey contents of the slope in the step 1 comprise the current vegetation situation, the altitude, the slope direction, the slope length,

Slope shape, soil type, texture, moisture, fertility conditions.

Selecting at least one of robinia pseudoacacia, Chinese pine, quercus, aspen, ailanthus altissima swingle, pistacia chinensis bunge, shiny-leaved yellowhorn, cypress, wild peach and wild apricot as a tree for planting;

at least one of sea buckthorn, caragana microphylla, amorpha fruticosa, Chinese wolfsberry root, yellow rose and wild jujube is selected as shrub for planting;

selecting at least one of Imperata cylindrica, Miscanthus floridulus, herba Hedyotidis Diffusae, herba Centellae, Lysimachia, Carex, caulis Seu folium Lespedezae Bicoloris, herba Viciae Pilosae, and Daghestan sweetclover as herbaceous plant.

And 3, taking the seedlings as main seedlings and selecting container seedlings cultured in a nutrition pot.

And 4, selecting scale pits in a slope land arrangement mode, wherein the scale pits are arranged in a shape like a Chinese character 'pin' on the slope.

In the step 4, the distance between every two adjacent fish scale pits is 1.5-3.0 m; the row spacing of the upper row of pits and the lower row of pits on the slope land is 3-5 m; the depth of the fish scale pits is 0.3-0.5 m.

The filling height of the middle part of the ridges of two adjacent fish scale pits is 0.2-0.3 m; the inner diameter of the semicircle of the ridge of the pit is 1 to

1.5m, and the middle of the ridge top is higher than the two ends of the ridge top.

In the step 5, the intercepting ditch adopts a trapezoidal or rectangular section, water stopping sills are built at two ends of the intercepting ditch, the width of the lower end surface of the intercepting ditch is 0.1-0.3m, the width of the upper end surface of the intercepting ditch is 0.3-0.5m, and the height of the intercepting ditch is 0.2-0.3 m.

And 6, uniformly mixing herbaceous seeds and sandy soil for planting the intercepting ditch grassland and then broadcasting.

The mixing ratio of the seeds to the sandy soil is 1: 100.

the method has the advantages that the method is mainly used for solving the problems of serious soil erosion and difficult treatment of the loess plateau trench wall, starts with reducing slope runoff water over the loess region trench wall, regulates and controls slope runoff paths, prolongs slope runoff time, disperses runoff erosion energy, strengthens slope runoff infiltration and reduces trench wall erosion kinetic energy through multiple runoff retaining methods such as fish scale pits and flexible ecological intercepting trenches in water and soil conservation vegetation construction engineering, so that the trench wall soil erosion amount is reduced, and the effect of effectively treating the loess region trench wall erosion is achieved. Compared with the existing vegetation construction mode, the vegetation construction method has the following advantages: (1) the water inflow amount of the slope surface above the trench wall is reduced, and the soil erosion pressure of the trench wall is reduced; (2) the interception amount of the slope runoff is increased, and the slope runoff erosion is reduced; (3) the infiltration amount of soil moisture is increased, and the supply amount of vegetation moisture is improved; (4) the distributed flexible ecological intercepting ditches can not only intercept runoff and increase infiltration, but also beautify the landscape of the slope.

Drawings

FIG. 1 is a schematic view of typical slope vegetation construction of loess plateau by using the vegetation construction method for reducing the soil erosion of the trench wall of the loess region.

In the figure, 1, a slope, 2, vegetation, 3, a fish scale pit and 4, a catch basin.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic view of typical slope vegetation construction of loess plateau by using the vegetation construction method for reducing the soil erosion of the trench wall of the loess region. In fig. 1, 1 is a slope, 2 is vegetation, 3 is a fish scale pit, and 4 is a catch basin.

The invention relates to a vegetation construction method for reducing soil erosion of a trench wall in a loess area, which specifically comprises the following steps:

step 1, surveying the slope surface ground conditions for vegetation construction; the survey contents of the slope on the ground in the step 1 comprise the current vegetation condition, the elevation, the slope direction, the slope length, the slope shape, the soil type, the texture, the moisture and the fertility condition.

Step 3, selecting seeds and nursery stocks of the plant variety screened in the step 2; seeds and seedlings used for vegetation construction meet the relevant regulations of national standard forest seed quality classification and main afforestation tree seedling quality classification, and seeds or seedlings cultivated in an improved variety base are preferably used as seed sources for vegetation construction. The selected nursery stock should be mainly seedling and the best container seedling cultured in a nutrition pot is selected.

Step 4, carrying out slope land finishing; the fish scale pits are selected as a main mode for slope forestation and land preparation. The fish scale pit soil preparation is suitable for afforestation on a slope with a slope of more than 15 degrees. When the rainfall and the rain intensity are small, the fish scale pits can directly block the water coming from the slope surface, and the functions of increasing soil infiltration, cutting off in sections and in fragments and blocking the runoff are achieved; when the rainfall and the rainfall intensity are large, the runoff blocked by the fish scale pits can flow out from two sides of the pits, so that the runoff concentration is avoided, and the runoff scouring capacity is reduced. The horizontal distance (pit distance) between the fish scale pits is 1.5-3.0 m (about 2 times the diameter of the pits), and the slope distance (row distance) between the upper row of pits and the lower row of pits is 3-5 m. The depth of the pit is about 0.4m, the filling height of the middle part of the ridge is about 0.2-0.3m, the inner slope is 1: 0.5, the outer slope is 1: 1, the inner diameter of the semicircle of the ridge of the pit is about 1-1.5 m, and the middle of the ridge top is higher than two ends. The pits on the slope surface are arranged alternately up and down and are in a triangle shape.

Step 5, designing a slope surface intercepting ditch on the slope surface land finished in the step 4; in order to further retain rainfall runoff and increase slope infiltration, horizontal intercepting ditches are arranged along the slope at intervals of a plurality of rows of fish scale pits.

The intercepting ditch adopts a trapezoidal or rectangular section, the width of the lower end surface is 0.1-0.3m, the width of the upper end surface is 0.3-0.5m, and the height is 0.2-0.3 m; and water blocking sills with the height of 0.2m are built at the two ends of the intercepting ditch.

And according to the slope length condition, arranging a plurality of intercepting ditches along the contour line, and determining the arrangement distance and the number of the intercepting ditches according to the control area, the regional rainfall, the slope runoff yield and the water storage capacity of the intercepting ditches.

The intercepting ditch can be connected with a drainage ditch which is longitudinally arranged, and runoff which cannot be stored on the slope surface can be led to a slope surface water storage project or a drainage basin channel according to design requirements under the condition of heavy rainstorm.

In order to reduce the risk of slope gravity erosion, the distance between the bottommost intercepting ditch and the slope bottom is not less than 4.0 m;

if the intercepting drain is too long, a soil block can be built in the intercepting drain to divide the intercepting drain into a plurality of sections.

The specific design standard of the intercepting ditch can refer to GB51018-2014 water and soil conservation engineering design standard, and the design of the intercepting ditch for the vegetation construction slope surface can be slightly lower than the standard in consideration of actual site conditions and cost factors.

When the seedlings are planted in the fish scale pits, the seedlings are kept upright, the planting depth is proper, and the root systems of the seedlings are fully extended;

the native grass seeds are planted in the intercepting ditch to form a flexible ecological ditch, which not only can reduce the inner diameter flow scouring of the ditch, but also can improve the soil structure and increase the infiltration of soil moisture.

The planting of intercepting ditch meadow adopts herbaceous seed and the broadcast sowing behind the sand soil misce bene, and seed and sand soil mixing ratio are 1: 100.

example 1

The test area is positioned on a certain abandoned slope of a small watershed of south ditch of Yanan city, Shanxi province, and the specific implementation steps are as follows:

step 1, surveying slope surface vertical conditions: the annual average rainfall capacity of the area is 510mm, and the rainfall capacity can meet the requirements of arbor afforestation. The implementation slope is a semi-yin slope, the slope is 67 meters long, the slope is 22 degrees, the soil type is yellow cotton soil, the vegetation distribution is that artemisia capillaris and artemisia zizanioides are main dominant grass seeds, and the secondary natural grassland community with the branch of lindera and carex incarnata as main associated grass seeds.

Step 2, plant variety selection: according to local climate and soil conditions, robinia pseudoacacia is selected as the slope water and soil to keep vegetation and build tree seeds, and carex incarnata is selected as the slope ecological intercepting ditch to plant grass seeds.

Step 3, selecting seeds and nursery stocks: the robinia pseudoacacia seedlings and the carex incarnata seeds selected in the embodiment are from a normal large-scale seedling base and meet the relevant national standards.

Step 4, slope land finishing: the fish scale pits are selected as a mode for slope afforestation and land preparation in the embodiment. The horizontal distance between the fish scale pits is 2.0m, and the distance between the upper row of pits and the lower row of pits is 3.0 m. The depth of the pit is about 0.4m, the filling height of the middle part of the ridge is about 0.3m, the filling height of the two sides is about 0.2m, the ratio of the inner slope to the outer slope is 1: 0.5, and the ratio of the inner slope to the outer slope is 1: 1, and the inner diameter of the semicircle of the ridge of the pit is about 1.0 m.

Step 5, designing a slope catch drain: according to the slope condition, 3 ecological intercepting ditches are designed on the slope surface of the example, and the distance between the intercepting ditches is 21.0 m. The intercepting ditch adopts a trapezoidal section, the width of the lower end surface is 0.2m, the width of the upper end surface is 0.4m, the height of the upper end surface is 0.3m, and water retaining ridges with the height of 0.2m are built at the two ends of the intercepting ditch. The distance between the lowest intercepting drain and the slope bottom is 4.0 m.

Step 6, slope vegetation construction: 1 locust seedling is planted at the position 1/2 on the left and right of the fish scale pit, the seedling is lifted and trampled after half of soil is filled, then the soil is filled and trampled, and finally the deficient soil is covered. In the ecological intercepting ditch, the Carex dactyloides seeds and loess are uniformly mixed and then sown, and the mixing ratio of the seeds to the sandy soil is 1: 100, sowing 0.25kg of grass seeds in each mu of land. And (5) in the 2 nd and 3 rd years after afforestation, replanting plots with substandard survival rate. The slope vegetation construction can be referred to the 'Water and soil conservation forest engineering design Specification' GB/T51097-2015.

The following table 1 shows the influence of different vegetation construction methods on slope water inflow and trench wall erosion (Yanan);

TABLE 1

Example 2

The test area is positioned on a certain abandoned slope surface of a small valley of Wangooncou Majongchi county, Shanxi province, and the specific implementation steps are as follows:

step 1, surveying slope surface vertical conditions: the average rainfall capacity of the area is 480mm for many years, and the rainfall capacity can meet the requirements of shrub afforestation. The slope surface is a half-sunny slope, the slope length is 61 meters, the slope is 20 degrees, the soil type is yellow-cotton soil, herbaceous communities such as sagebrush, lysimachia and the like are distributed on the slope surface, and the grassland coverage is about 50 percent.

Step 2, plant variety selection: according to local climate and soil conditions, amorpha fruticosa is selected as a slope water and soil conservation vegetation construction tree species, and grass is planted in the slope ecological intercepting ditches.

Step 3, selecting seeds and nursery stocks: the amorpha fruticosa seedlings and the lysimachia seeds selected in the embodiment are from normal large seedling bases and meet the relevant national standards.

Step 4, slope land finishing: the fish scale pits are selected as a mode for slope afforestation and land preparation in the embodiment. The horizontal distance between the fish scale pits is 1.5m, and the distance between the upper row of pits and the lower row of pits is 3.0 m. The depth of the pit is about 0.3m, the filling height of the middle part of the ridge is about 0.3m, the filling height of the two sides is about 0.2m, the ratio of the inner slope to the outer slope is 1: 0.5, and the semi-circle inner diameter of the ridge of the pit is about 0.8 m.

Step 5, designing a slope catch drain: according to the slope condition, 3 ecological intercepting ditches are designed on the slope surface of the example, and the distance between the intercepting ditches is 19.0 m. The intercepting ditch adopts a trapezoidal section, the width of the lower end surface is 0.2m, the width of the upper end surface is 0.4m, the height of the upper end surface is 0.3m, and water retaining ridges with the height of 0.2m are built at the two ends of the intercepting ditch. The distance between the lowest intercepting drain and the slope bottom is 4.0 m.

Step 6, slope vegetation construction: 1 amorpha fruticosa seedling is planted at the position 1/2 left and right of the scale pit, the seedling is lifted and trampled after half of soil is filled, then the soil is filled and trampled, and finally the deficient soil is covered. In ecological intercepting ditch, broadcast the seeding after mixing grass seed and loess evenly, seed and sand soil mixing ratio are 1: 100, sowing 0.25kg of grass seeds in each mu of land. And (5) in the 2 nd and 3 rd years after afforestation, replanting plots with substandard survival rate. The slope vegetation construction can be referred to the 'Water and soil conservation forest engineering design Specification' GB/T51097-2015. The following table 2 shows the influence of different vegetation construction methods on slope water inflow and trench wall erosion (seidel).

TABLE 2

The invention provides a slope vegetation construction method for reducing soil erosion of a trench wall of a loess area, which can be used for the engineering design of newly-built water and soil conservation forest and the engineering design of water and soil conservation forest reconstruction in the loess plateau area. The method is scientific in design and simple and convenient to operate, and by jointly using water and soil conservation vegetation construction technologies such as the fish scale pits and the ecological intercepting ditches, the rainfall can be effectively intercepted, the water infiltration is increased, the vegetation is promoted to grow quickly and stably, the water above the slope surface is reduced, the runoff erosion energy is reduced, the soil erosion of the ditch walls is reduced, and the regional water and soil loss treatment is promoted.

Claims

1. A vegetation construction method for reducing soil erosion of a trench wall in a loess area is characterized by comprising the following steps: the method specifically comprises the following steps:

the survey contents of the slope in the step 1 comprise the current vegetation condition, the elevation, the slope direction, the slope length, the slope shape, the soil type, the texture, the moisture and the fertility condition;

at least one of robinia pseudoacacia, Chinese pine, quercus, aspen, ailanthus altissima swingle, pistacia chinensis bunge, shiny-leaved yellowhorn, cypress, wild peach and wild apricot is selected in the step 2 to be planted as a tree;

selecting at least one of Imperata cylindrica, Miscanthus floridulus, herba Hedyotidis Diffusae, herba Ipomoeae, Larix Gmelini, Carex, caulis Seu folium Lespedezae Bicoloris, herba Viciae Pilosae, and Daghestan Sweetclover as herbaceous plant for planting;

in the step 3, the seedlings are mainly seedlings, and container seedlings cultured by using a nutrition pot are selected;

step 4, carrying out slope land finishing;

step 4, selecting scale pits in a slope land arrangement mode, wherein the scale pits are arranged on the slope in a shape like a Chinese character 'pin';

the pit distance between every two adjacent fish scale pits in the step 4 is 1.5-3.0 m; the row spacing of the upper row of pits and the lower row of pits on the slope land is 3-5 m; the depth of the fish scale pits is 0.3-0.5 m;

the filling height of the middle part of the ridges of two adjacent fish scale pits is 0.2-0.3 m; the inner diameter of the semicircle of the pit ridge is 1-1.5 m, and the middle of the ridge top is higher than the two ends of the ridge top;

in the step 5, the intercepting ditch adopts a trapezoidal or rectangular section, water stopping sills are built at two ends of the intercepting ditch, the width of the lower end surface of the intercepting ditch is 0.1-0.3m, the width of the upper end surface of the intercepting ditch is 0.3-0.5m, and the height of the intercepting ditch is 0.2-0.3 m;

step 6, planting the seeds and seedlings screened in the step 3 on the slope land of the intercepting ditch designed in the step 5;

in the step 6, the cut-off ditch grassland is planted by uniformly mixing herbaceous seeds with sandy soil and then sowing the mixture; the mixing ratio of the seeds to the sandy soil is 1: 100.