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

Abstract

The invention discloses a vegetation construction method for reducing soil erosion of ditch walls in a loess area. In step 1, the site conditions of slopes where vegetation construction is to be carried out are investigated; Select plant varieties planted under different site conditions on the plateau; step 3, select seeds and seedlings for the plant varieties screened in step 2; step 4, carry out slope land preparation; step 5, slope land after step 4 Design the intercepting ditch on the slope; in step 6, the seeds and seedlings screened in step 3 are planted on the slope land where the intercepting ditch is designed in step 5. The invention effectively reduces the soil erosion of the ditch wall by reducing the inflow of slope runoff and changing the runoff path, and provides technical support for regional soil erosion control and ecological civilization construction.

Description

A vegetation construction method to reduce soil erosion of ditch 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 ditch walls in loess areas.

Background technique

The Loess Plateau is the region with the most serious soil erosion in my country and even in the world, and it is also a key region for soil and water conservation and ecological restoration. In order to curb the soil erosion on the Loess Plateau and improve the ecological environment and people's lives in the area, since the founding of the People's Republic of China, the Loess Plateau has undergone several treatments such as slope management, joint management of ditch and slope, comprehensive management of small watersheds, and returning farmland to forest (grass). stage. After more than 70 years of scientific management and comprehensive prevention and control, the area of soil and water conservation measures in the Loess Plateau has reached 213,000 km ² , and nearly half of the area of soil and water loss has been initially treated. The vegetation coverage rate of the Loess Plateau has increased from less than 20% in the 1980s to the current 63%, and the amount of sediment entering the loess has dropped from 1.3 billion tons per year in the 1970s to less than 300 million tons per year.

Although the soil erosion on the Loess Plateau has been initially curbed and the ecological environment has been significantly improved, due to the loose porosity of the loess structure, the fragmentation of regional terrain and the concentration of rainfall time, the risk of soil erosion in this area is still very high. The regional sand production is still likely to exceed 1 billion tons. Studies have shown that the eroded sediment in the Loess Plateau mainly comes from gully, and the erosion of gully wall usually accounts for more than 60% of the total erosion in the basin. In addition, with the restoration of vegetation on the slope, the sediment content of the slope runoff decreased, and the sediment carrying capacity of the runoff was further enhanced, which intensified the erosion risk of the valley wall. Therefore, how to reduce the soil erosion of the ditch wall in the loess area and further reduce the amount of water and soil loss in the area is one of the bottleneck problems that needs to be overcome urgently in the current control of water and soil loss in the Loess Plateau.

Vegetation construction is an important way to control soil erosion on the Loess Plateau. Vegetation intercepts and stores runoff through the canopy to increase rainfall infiltration; through root consolidation and soil structure improvement, the kinetic energy of raindrops is dissipated, the storage capacity of soil reservoirs is improved, and the anti-scourability of soil is enhanced, thereby preventing soil erosion and reducing water and soil. drain effect. The existing soil and water conservation vegetation construction on the Loess Plateau mainly adopts the method of planting trees and grass on the ditch slope to reduce soil erosion on the slope surface by increasing the vegetation coverage. Although the soil erosion on the slope decreased significantly with the increase of the vegetation coverage, the erosion of the ditch wall was increased invisibly because the influence of the decrease in the sediment content of the slope runoff and the enhancement of the sand carrying capacity after the increase of vegetation was not considered. The ditch wall is located in the valley area below the mao sideline, with a large slope and exposed loess, making it difficult to control. Soil erosion on the ditch wall is an important source of soil erosion on the Loess Plateau. Effective prevention and control of soil erosion on the ditch wall is a key link in the success of soil erosion control on the Loess Plateau, and is of great significance to the construction of regional ecological civilization.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a vegetation construction method for reducing the soil erosion of the ditch wall in the loess area. The method effectively reduces the soil erosion of the ditch wall by reducing the inflow of slope runoff and regulating the runoff path, which is conducive to the control of regional water and soil loss and the construction of ecological civilization. Provide technical support.

The technical scheme adopted in the present invention is a vegetation construction method for reducing soil erosion of ditch walls in loess area, which specifically includes the following steps:

Step 1: Investigate the site conditions of the slope where vegetation construction is to be carried out;

Step 2, according to the survey results of the slope site conditions in step 1, select plant varieties grown under different site conditions on the Loess Plateau;

Step 3, the selection of seeds and seedlings is performed on the plant varieties screened in step 2;

Step 4, carry out slope land preparation;

Step 5, design the slope intercepting ditch on the slope land sorted in step 4;

Step 6: Plant the seeds and seedlings screened in Step 3 on the slope land of the intercepting ditch designed in Step 5.

The present invention is also characterized in that,

In step 1, the site survey on the slope surface includes current vegetation status, altitude, slope, slope aspect, slope length,

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

In step 2, select at least one of Robinia pseudoacacia, Pinus tabulaeformis, Quercus, Aspen, Ailanthus, Pistacia chinensis, Wenguanguo, Cypress, Mountain Peach, and Mountain Apricot to be planted as arbors;

Select at least one of sea buckthorn, caragana, amorpha, wolf tooth thorn, yellow thorn rose, and jujube as a shrub to plant;

Select at least one of Stipa, Miscanthus, White Leymus, Icegrass, Laygrass, Caryophyllaceae, Viticola, Vetch, and Cinnamon as herbs for planting.

In step 3, the seedlings are mainly seedlings, and the container seedlings cultivated in the nutrient bowl are selected.

Step 4 The method of land preparation on the slope surface is to use fish scale pits, and the fish scale pits are arranged in a zigzag shape on the slope surface.

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

The filling height of the middle part of the soil ridge between two adjacent fish scale pits is 0.2~0.3m; the inner diameter of the semicircle of the pit ridge is 1~0.3m

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

In step 5, the intercepting ditch adopts trapezoidal or rectangular cross-section, and the two ends of the intercepting ditch are built with water retaining ridges.

In step 6, the grass seed and sandy soil are evenly mixed for grass planting in the intercepting ditch and then sown.

The mixing ratio of seeds and sand is 1:100.

The beneficial effect of the present invention is that, the present invention mainly aims at the serious soil erosion of the ditch wall in the Loess Plateau and the problem of difficulty in treatment, starting from reducing the inflow of runoff on the slope surface above the ditch wall in the loess area, and in the soil and water conservation vegetation construction project through fish scale pits and flexible Multiple runoff interception methods such as ecological interception ditch, regulate slope runoff path, extend slope runoff time, disperse runoff erosion energy, strengthen slope runoff infiltration, reduce ditch wall erosion kinetic energy, thereby reducing ditch wall soil erosion, and achieve Effective control of ditch wall erosion in loess area. Compared with the existing vegetation construction mode, the present invention has the following advantages: (1) the inflow of the slope above the ditch wall is reduced, and the soil erosion pressure of the ditch wall is reduced; (2) the interception of the slope runoff is increased, and the Slope runoff erosion; (3) increased soil water infiltration and increased vegetation water supply; (4) the flexible ecological interception ditch laid out not only can intercept runoff and increase infiltration, but also beautify the slope landscape. effect.

Description of drawings

Fig. 1 is a schematic diagram of the vegetation construction on a typical slope of the Loess Plateau using a vegetation construction method of the present invention for alleviating the soil erosion of the ditch wall in the Loess Plateau.

In the figure, 1. Slope, 2. Vegetation, 3. Fish scale pit, 4. Intercepting ditch.

Detailed ways

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

Fig. 1 is a schematic diagram of the vegetation construction on a typical slope of the Loess Plateau using a vegetation construction method for reducing soil erosion of ditch walls in the loess region of the present invention. In Figure 1, 1 is the slope, 2 is the vegetation, 3 is the fish scale pit, and 4 is the intercepting ditch.

The present invention is a vegetation construction method for reducing soil erosion of ditch walls in loess area, which specifically comprises the following steps:

Step 1: Investigate the conditions of the slope site where vegetation construction is to be carried out; in Step 1, the survey contents of the slope site include vegetation status, elevation, slope, slope aspect, slope length, slope shape, soil type, texture, moisture, and fertility conditions .

Step 2, according to the survey results of the slope site conditions in step 1, select plant varieties grown under different site conditions on the Loess Plateau;

In step 2, select at least one of Robinia pseudoacacia, Pinus tabulaeformis, Quercus, Aspen, Ailanthus, Pistacia chinensis, Wenguanguo, Cypress, Mountain Peach, and Mountain Apricot to be planted as arbors;

Select at least one of sea buckthorn, caragana, amorpha, wolf tooth thorn, yellow thorn rose, and jujube as a shrub to plant;

Select at least one of Stipa, Miscanthus, White Leymus, Icegrass, Laygrass, Caryophyllaceae, Viticola, Vetch, and Cinnamon as herbs for planting.

Step 3, select the seeds and seedlings for the plant varieties screened in step 2; the seeds and seedlings used for vegetation construction should comply with the relevant regulations of the national standard "Quality Classification of Forest Tree Seeds" and "Quality Classification of Main Afforestation Tree Species and Seedlings". The cultivated seeds or seedlings are used as the provenance for vegetation construction. The selected seedlings should be mainly seedlings, and container seedlings cultivated in nutrient pots are the best.

Step 4, carry out land preparation on the slope; choose fish scale pits as the main method of land preparation for afforestation on the slope. Fish scale pit site preparation is suitable for afforestation on slopes with a slope of more than 15°. When the rainfall and rain intensity are small, the fish scale pit can directly store the water coming from the slope, which can increase soil infiltration, cut off the runoff in sections and pieces, and store the runoff; Runoff can flow out from both sides of the pit, avoiding runoff concentration and reducing runoff scour capacity. The horizontal distance (pit distance) between the fish scale pits is 1.5 to 3.0m (about twice the diameter of the pit), and the slope distance (row distance) of the upper and lower rows of pits is 3 to 5m. The depth of the pit is about 0.4m, the middle part of the soil ridge is filled with a height of about 0.2-0.3m, the inner slope is 1:0.5, the outer slope is 1:1, the inner diameter of the semi-circle of the pit ridge is about 1-1.5m, and the middle of the ridge top should be higher than the two ends. The arrangement of the pits on the slope is alternately up and down, in the shape of a zigzag.

Step 5: Design a slope intercepting ditch on the slope land sorted in Step 4; in order to further store rainfall runoff and increase slope infiltration, lay horizontal intercepting ditches every several rows of fish scale pits along the slope.

The intercepting ditch adopts trapezoidal or rectangular section, the width of the lower end is 0.1-0.3m, the width of the upper end is 0.3-0.5m, and the height is 0.2-0.3m; the two ends of the intercepting ditch are constructed with 0.2m-high retaining ridges.

According to the slope length, lay a number of intercepting ditches along the contour line, and determine the spacing and number of their layout according to their control area, regional rainfall, slope runoff and water storage capacity.

The intercepting ditch can be connected with the longitudinally arranged drainage ditch, and under heavy rainstorm conditions, the runoff that cannot be retained on the slope surface can be led to the slope surface water storage project or the drainage channel according to the design requirements.

In order to reduce the risk of gravity erosion on the slope, the distance between the lowermost intercepting ditch and the bottom of the slope shall not be less than 4.0m;

If the intercepting ditch is too long, an earth block can be built in the intercepting ditch, and the intercepting ditch can be divided into several sections.

For the specific design standards of the intercepting ditch, please refer to "GB51018-2014 Design Specifications for Soil and Water Conservation Engineering". Considering the actual site conditions and cost factors, the design of the intercepting ditch on the slope for vegetation construction can be slightly lower than the above standards.

Step 6: Plant the seeds and seedlings screened in Step 3 on the slope land of the intercepting ditch designed in Step 5.

When planting seedlings in the fish scale pit, keep the seedlings upright, the planting depth is suitable, and the root system of the seedlings is fully stretched;

Planting native grass seeds in the intercepting ditch to form a flexible ecological ditch can not only reduce the runoff erosion in the ditch, but also improve the soil structure and increase the infiltration of soil water.

For grass planting in the intercepting ditch, herb seeds and sandy soil are mixed evenly and then sown. The mixing ratio of seeds and sandy soil is 1:100.

Example 1

The test area is located on an abandoned slope in the Nangou small watershed of Yan'an City, Shaanxi Province. The specific implementation steps are as follows:

Step 1. Investigation of slope site conditions: The average annual rainfall in this area is 510mm, which can meet the needs of arbor afforestation. The implemented slope is a semi-shady slope with a slope length of 67 meters and a slope of 22°. The soil type is loess soil. The vegetation distribution is mainly dominated by Artemisia annua L. and Artemisia annua L. Secondary natural grassland communities of grass species.

Step 2: Plant species selection: According to local climate and soil conditions, Robinia pseudoacacia is selected as the tree species for soil and water conservation vegetation construction on the slope, and Lichen lanceolus is the grass species planted in the ecological intercepting ditch on the slope.

Step 3, selection of seeds and seedlings: The Robinia pseudoacacia seedlings and the lanceolate grass seeds selected in this example are from regular large-scale seedling bases and meet relevant national standards.

Step 4, land preparation on slope surface: In this example, fish scale pit is selected as the method of land preparation for afforestation on the slope surface. The horizontal distance between the fish scale pits is 2.0m, and the distance between the upper and lower rows of pits is 3.0m. The depth of the pit is about 0.4m, the middle part of the soil ridge is filled with a height of about 0.3m, the two sides are filled with a height of about 0.2m, the inner slope is 1:0.5, the outer slope is 1:1, and the inner diameter of the semicircle of the pit ridge is about 1.0m.

Step 5. Design of intercepting ditches on slope: According to the situation of the slope, three ecological intercepting ditches are designed on the slope of this example, and the interval between intercepting ditches is 21.0m. The intercepting ditch adopts a trapezoidal section, with a width of 0.2m at the lower end, a width of 0.4m at the upper end and a height of 0.3m. The two ends of the interception ditch are constructed with dams of 0.2m in height. The lowermost intercepting ditch is 4.0m away from the bottom of the slope.

Step 6, vegetation construction on the slope: plant a locust seedling on the left and right 1/2 of the fish scale pit, fill half of the soil, lift the seedlings and step on them, then fill the soil and step on them, and finally cover with virtual soil. In the ecological water intercepting ditch, the seeds of Lichen lanceolata were mixed with loess and then sown. The mixing ratio of seeds and sandy soil was 1:100, and 0.25 kg of grass seeds were sown per mu. In the 2nd and 3rd years after afforestation, replant the plots whose survival rate does not meet the standard. For details on slope vegetation construction, please refer to "Code for Design of Soil and Water Conservation Forest Engineering" GB/T51097-2015.

The following table 1 shows the influence of different vegetation construction methods on slope inflow and ditch wall erosion (Yan'an);

Table 1

Example 2

The test area is located on a deserted slope in the Wangmaogou small watershed of Suide County, Shaanxi Province. The specific implementation steps are as follows:

Step 1. Investigation of site conditions on slopes: The average annual rainfall in this area is 480mm, which can meet the needs of shrub afforestation. The implemented slope is a semi-sunny slope, with a slope length of 61 meters and a slope of 20°. The soil type is loess soil. The slope is distributed with herbaceous communities such as Artemisia annua L. and Lai grass, and the grassland coverage is about 50%.

Step 2, plant species selection: According to the local climate and soil conditions, Amorpha is selected as the tree species for soil and water conservation vegetation construction on the slope, and Lai grass is the grass species planted in the ecological intercepting ditch on the slope.

Step 3, the selection of seeds and seedlings: the seeds of Amorpha japonica and the seeds of Amorpha japonica selected in this example are from regular large-scale seedling bases and conform to relevant national standards.

Step 4, land preparation on slope surface: In this example, fish scale pit is selected as the method of land preparation for afforestation on the slope surface. The horizontal distance between the fish scale pits is 1.5m, and the distance between the upper and lower rows of pits is 3.0m. The depth of the pit is about 0.3m, the middle part of the soil ridge is filled with a height of about 0.3m, the two sides are filled with a height of about 0.2m, the inner slope is 1:0.5, the outer slope is 1:1, and the inner diameter of the semicircle of the pit ridge is about 0.8m.

Step 5. Design of intercepting ditches on slope: According to the situation of the slope, three ecological intercepting ditches are designed on the slope of this example, and the interval between intercepting ditches is 19.0m. The intercepting ditch adopts a trapezoidal section, with a width of 0.2m at the lower end, a width of 0.4m at the upper end and a height of 0.3m. The two ends of the interception ditch are constructed with dams of 0.2m in height. The lowermost intercepting ditch is 4.0m away from the bottom of the slope.

Step 6, vegetation construction on the slope: plant 1 amorpha seedling on the left and right 1/2 of the fish scale pit, fill half of the soil, lift the seedlings and step on them, then fill the soil and step on them, and finally cover with virtual soil. In the ecological water intercepting ditch, the seeds of Lai Cao Cao were evenly mixed with loess and then sown. The mixing ratio of seeds and sandy soil was 1:100, and 0.25 kg of grass seeds were sown per mu of land. In the 2nd and 3rd years after afforestation, replant the plots whose survival rate does not meet the standard. For details on slope vegetation construction, please refer to "Code for Design of Soil and Water Conservation Forest Engineering" GB/T51097-2015. Table 2 below shows the impact of different vegetation construction methods on slope inflow and ditch wall erosion (Suide).

Table 2

The invention provides a slope vegetation construction method for reducing soil erosion of ditch walls in the loess area, which can be used for the design of new water and soil conservation forest projects and the design of water and soil conservation forest renovation projects in the loess plateau area. The method is scientific in design and easy to operate. By using fish scale pits and ecological intercepting ditch and other soil and water conservation vegetation construction technologies, it can effectively store precipitation, increase water infiltration, promote rapid and stable growth of vegetation, reduce water coming from above the slope, and reduce runoff. Erosion energy, reduce soil erosion on the ditch wall, and promote regional soil erosion control.

Claims (1)

1. a vegetation construction method for alleviating ditch wall soil erosion in loess district, is characterized in that: specifically comprise the steps: Step 1: Investigate the site conditions of the slope where vegetation construction is to be carried out; In the step 1, the content of the site investigation on the slope surface includes current vegetation status, altitude, slope, slope aspect, slope length, slope shape, soil type, texture, moisture, and fertility conditions; Step 2, according to the survey results of the slope site conditions in step 1, select plant varieties grown under different site conditions on the Loess Plateau; In described step 2, select at least one of Robinia pseudoacacia, Pinus tabulaeformis, Quercus, Aspen, Ailanthus sinensis, Pistacia chinensis, Radix Arborvitae, Cypress, Mountain Peach, Mountain Apricot to be planted as arbors; Select at least one of sea buckthorn, caragana, amorpha, wolf tooth thorn, yellow thorn rose, and jujube as a shrub to plant; Select at least one of Stipa, Miscanthus, White Leymus, Icegrass, Laygrass, Caryophyllae, Viticola, Vetch, and Cinnamon as herbs for planting; Step 3, the selection of seeds and seedlings is performed on the plant varieties screened in step 2; In the described step 3, the seedlings are mainly seedlings, and the container seedlings cultivated in the nutrient bowl are selected for use; Step 4, carry out slope land preparation; Described step 4, the method of land preparation on slope surface selects fish scale pits, and fish scale pits are arranged on the slope surface in the shape of a character; In the step 4, the pit spacing between two adjacent fish scale pits is 1.5-3.0m; the row spacing of the upper and lower rows of pits on the slope land is 3-5m; the depth of the fish-scale pits is 0.3-0.5m; The filling height of the middle part of the soil ridge of two adjacent fish scale pits is 0.2 to 0.3 m; the inner diameter of the semicircle of the pit ridge is 1 to 1.5 m, and the middle of the ridge top is higher than both ends of the ridge top; Step 5, design the slope intercepting ditch on the slope land sorted in step 4; In the step 5, the intercepting ditch adopts a trapezoidal or rectangular section, and the two ends of the intercepting ditch are built with water retaining ridges. ; Step 6, the seeds and seedlings screened in step 3 are planted on the slope land of the design intercepting ditch in step 5; In the step 6, the grass seed and the sandy soil are evenly mixed for planting the grass in the intercepting ditch and then sowed; the mixing ratio of the seed and the sandy soil is 1:100.

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