Regulation of techniques for comprehensive control of soil erosion-Technique for erosion control of slope land
Some standard content:
National Standard of the People's Republic of China
GB/T16453.1
Technical Specification for Comprehensive Control of Soil and Water Conservation-Technique for Erosion Control of Slopeland
Published on 1996-06-25
National Technical Supervision
Implementation on 1996-09-01
National Standard of the People's Republic of China
Technical Specification for Comprehensive Control of Soil and Water Conservation-Technique for Erosion Control of Slopeland slopeland
GB/T16453.1—1996
This standard series consists of four items: the first item "General Principles of Soil and Water Conservation Comprehensive Management Planning", the second item "Technical Specifications for Soil and Water Conservation Comprehensive Management", the third item "Acceptance Specifications for Soil and Water Conservation Comprehensive Management", and the fourth item "Calculation Methods for Benefits of Soil and Water Conservation Comprehensive Management". This standard is the second item in the above series.
This standard includes 6 standards:
GB/T16453.1-1996 Technical specification for comprehensive management of soil and water conservation Sloping farmland management technology GB/T16453.2-1996 Technical specification for comprehensive management of soil and water conservation Wasteland management technology GB/T16453.3-1996 Technical specification for comprehensive management of soil and water conservation Ditch preparation and management technology GB/T16453.4-1996 Technical specification for comprehensive management of soil and water conservation Small-scale water storage, drainage and diversion projects GB/T16453.5-1996 Technical specification for comprehensive management of soil and water conservation Wind and sand control technology GB/T16453.6-1996 Technical specification for comprehensive management of soil and water conservation Collapse control technology This standard is GB/T16453.1, including two contents: water and soil conservation farming methods and terraces. Appendix A of this standard is a reminder appendix. After the publication of the four items in this standard series, they will all replace the standard SD238-87 "Technical Specifications for Soil and Water Conservation" issued by the Ministry of Water Resources and Electric Power of the People's Republic of China in 1988. This standard is proposed and managed by the Ministry of Water Resources of the People's Republic of China. The responsible drafting unit of this standard is the Soil and Water Conservation Department of the Ministry of Water Resources. Participating drafting units are: Yellow River Upper and Middle Reaches Administration Bureau of the Yellow River Water Conservancy Commission, Rural Water Conservancy and Soil Conservation Bureau of the Yellow River Water Conservancy Commission, Soil and Water Conservation Bureau of the Yangtze River Water Conservancy Commission, Farmland Water Conservancy Department of the Songliao Water Conservancy Commission, Farmland Water Conservancy Department of the Pearl River Water Conservancy Commission, Farmland Water Conservancy Department of the Haihe Water Conservancy Commission, and Farmland Water Conservancy Department of the Huaihe Water Conservancy Commission. The main drafters of this standard are: Guo Tingfu, Liu Wanquan, Liao Chunyan, Hu Yufa, Ma Zhizun, Lu Shengli, Xu Chuanzao, Tong Weili, Ning Duihu. Part I: Water and Soil Conservation Tillage Methods
1 Scope
This part specifies the classification, adaptation conditions and specific practices of water and soil conservation tillage methods on sloping cultivated land. This part is applicable to water erosion areas and areas where water erosion and wind erosion are interlaced throughout the country. 2 Basic provisions
2.1 Water and Soil Conservation Tillage Methods
On sloping cultivated land, in combination with annual agricultural cultivation, various tillage methods are adopted to change the micro-topography, increase the ground plant cover, increase soil infiltration, and improve the soil's anti-erosion performance, so as to conserve water and soil, reduce soil erosion, and increase crop yields. 2.2 Classification of water-conserving and soil-conserving farming methods
2.2.1 The first category is the water-conserving and soil-conserving farming methods that change the micro-topography, mainly including: contour farming, furrow planting, hollow planting, drought-resistant and high-yield furrows, horizontal furrows on fallow land, etc.
2.2.2 The second category is the water-conserving and soil-conserving farming methods that increase ground plant cover, mainly including: grass-field rotation, intercropping, interplanting, strip intercropping, reasonable dense planting, and planting green manure on fallow land, etc.
2.2.3 The third category is the water-conserving and soil-conserving farming methods that increase soil infiltration and improve soil erosion resistance, mainly including: deep plowing, deep loosening, increased application of organic fertilizers, stubble sowing, etc.
2.3 Before implementing the water-conserving and soil-conserving farming methods, a comprehensive plan for the management of sloping farmland should be carried out with small watersheds as units. According to different terrain, soil quality, rainfall and other conditions, various types of terraces, soil conservation farming methods and small slope storage and drainage projects are set up respectively. The soil conservation farming method is used to manage the sloping farmland with an angle of less than 25° and no terraces.
2.4 While adopting the soil conservation farming method, small slope storage and drainage projects need to be set up inside the sloping farmland and on the upper outer side to prevent external water from entering. 2.5 The specific practices and related specifications and dimensions of each soil conservation farming method have different adaptability conditions; they should be formulated and reasonably determined according to the different terrain, soil quality, rainfall and agricultural farming conditions in various places. 3 The first type of soil conservation farming method
Combined with agricultural farming, the micro-topography of the sloping farmland is changed so that it can store rainwater and facilitate farming, so as to reduce soil erosion and increase crop yields.
3.1 Contour farming (also known as cross-slope farming)
3.1.1 In the dry and rainless areas in northern my country, the farming direction is required to be basically along the contour line to facilitate water and soil conservation. In the rainy and heavy soil areas in southern my country, the farming direction should be 1% to 2% lower than the contour line to adapt to drainage and prevent erosion. The ditch planting and horizontal furrows in leisure land measures taken on the basis of cross-slope farming are handled in accordance with this principle. 3.1.2 When the original slope furrows are changed to cross-slope furrows, they should be plowed first, and then cross-slope farming should be carried out to form new cross-slope furrows. 3.1.3 For sloping farmland that implements cross-slope farming, from top to bottom, at a certain distance, several soil strips should be built along the contour line, or grass belts and shrub belts should be planted, or horizontal furrows should be made with two sets of plows to shorten the slope and reduce soil erosion. 3.1.3.1 The initial height of soil is 40-50cm, and the width of grass belt is about 1m. When tilling every year, turn the soil from top to bottom to gradually reduce the ground slope between the two (or two belts), and at the same time increase the height by 10-20cm every year to gradually form horizontal terraces. 3.1.3.2 The distance between soil burial or grass belt varies with different slopes and rainfall conditions: the spacing is smaller in places with steep slopes and heavy rainfall; the spacing is larger in places with gentle slopes and light rainfall. Generally, the spacing is 8-15m for steep slopes above 15°, and 20-30m for gentle slopes below 10°. 3.1.4 In areas with gentle slopes with wind erosion, when changing the slope tillage to cross-slope tillage, the tillage direction should be perpendicular to the main wind direction, or at a 45° angle. 3.2 Furrow planting
On sloping cultivated land, cultivate along the contour line (or with a gradient of 1% to 2% with the contour line) to form a ground with alternating furrows and furrows to store rainwater and reduce soil erosion.
3.2.1 Plowing when sowing. This is done by livestock pulling the plow, and the following steps are followed: 3.2.1.1 Leave one plow width of ground unplowed below the plot, and from the second plow position, plow the first furrow along the contour line, turn the soil downward, and form the first furrow. The depth from the top of the furrow to the bottom of the furrow is about 20 to 30 cm, and seeds and fertilizers are scattered in the furrow. 3.2.1.2 Plow half a furrow depth above this furrow, and cover the seeds and fertilizers in the furrow with loose soil. 3.2.1.3 Leave another plow width of ground unplowed, and plow the second furrow along the contour line above it, turn the soil downward, and form the second furrow alternating with furrows. Thereafter, follow the above steps in sequence.
3.2.1.4 Make a small soil every 3-5m in the ditch, about 10cm high, and the small soil between two adjacent furrows is staggered in the shape of a "品". 3.2.2 Make a ridge when intertillage. Mainly used for high-stalk intertillage crops such as corn and sorghum. Operate manually and follow the following steps 3.2.2.1 Sow along the contour lines on the sloping cultivated land, and do not make a ridge when sowing. 3.2.2.2 During the first intertillage (seedling height 30-40cm), use the king between the seedling rows to pick up and cultivate at the roots of the seedlings; horizontal furrows are continuously formed at the soil taking place, and contour ridges are continuously formed at the soil cultivation place. 3.2.2.3 When taking soil, leave a small soil of about 10cm high every 3-5m in the ditch, and the small soil between two adjacent furrows is staggered in the shape of a "品". 3.2.3 Make a ridge in the shape of a "哇". Suitable for planting crops such as red sorghum in southern my country, operated manually, the steps are as follows: 3.2.3.1 Make gullies on the slope according to the steps in 3.2.1. 3.2.3.2 Leave a field path every 5 to 6 gullies, which also serves as a drainage channel to form a long slope; make a horizontal gully every 20 to 30 meters along the drainage channel to separate the long gullies into short gullies.
3.3 Digging and planting in pots
Applicable to arid and semi-arid areas, operated manually, 3.3.1 One pot one seedling method:
3.3.1.1 Use a hoe to dig holes (digging pots) along the contour lines on the sloping cultivated land, with the crop spacing as the hole spacing (generally 30 to 40 cm), and the crop row spacing as the row spacing between the upper and lower rows of holes (generally 60 to 80 cm). 3.3.1.The diameter of the 2 holes is generally 20-25cm, and the depth is about 20-25cm. The positions of the upper and lower rows of holes are staggered in the shape of a "品" character. 3.3.1.3 The raw soil taken out from the hole is made into a small soil below the hole, and then the bottom of the hole is loosened. 10cm of topsoil is taken from the second hole and placed in the first hole. Base fertilizer is applied and seeds are sown.
3.3.1.4 The same method is used for each subsequent hole so that there is topsoil in each hole. 3.3.2 One pot and several seedlings method:
3.3.2.1 Dig holes along the contour lines on the sloping cultivated land. The diameter of the hole is about 50cm and the depth is about 30-40cm. The raw soil taken out from the hole is made into a small soil below the hole. The distance between holes is about 50cm.
3.3.2.2 Dig the hole bottom loosely to a depth of about 15-20cm, then take about 10-15cm of the topsoil at a position of about 50cm×50cm above the hole, spread it evenly on the hole bottom, apply base fertilizer, sow seeds, and plant 2-3 plants in each hole according to different crop conditions. 3.3.2.3 The row spacing of the holes is based on the row spacing of the crops, and the positions of the holes in the upper and lower rows are staggered in a "品" shape. 3.4 Drought-resistant and high-yield furrows
Applicable to arid and semi-arid areas with deep soil layers. 3.4.1 Manual operation steps are shown in Figure 1:
Topsoil into the structure
First loosening
Figure 1 Drought-resistant and high-yield ditch manual operation steps
Topsoil into the ditch
3.4.1.1 Starting from the bottom of the sloping farmland, about 30 cm away from the edge of the ground, dig a ditch about 30 cm wide and 20-25 cm deep along the contour line. The excavated topsoil is temporarily piled above the ditch, see Figure 1 (a). 3.4.1.2 Dig out the raw soil in the ditch and pile it below the ditch to form the first soil, see Figure 1 (b). 3.4.1.3 Loosen the bottom of the ditch with a shovel, 20-25 cm deep, see Figure 1 (c). 3.4.1.4 Push the topsoil temporarily piled above the ditch into the ditch; at the same time, take up the topsoil of the original ground above the ditch, which is about 60cm wide and 20cm deep, and push it into the ditch to roughly fill the ditch, see Figure 1 (d). 3.4.1.5 On the 60cm wide ground without the topsoil, dig a ditch at the upper 30cm wide position and 20-25cm deep. Pile the excavated raw soil at the lower 30cm wide position to make the second soil, see Figure 1 (e). 3.4.1.6 Loosen the bottom of the second ditch to a depth of 20-25cm, see Figure 1 (f). 3.4.1.7 Take up the topsoil about 60cm wide above the bottom of the second ditch to a depth of about 20cm and push it into the second ditch, see Figure 1 (g). Continue in this way until the entire slope is made of raw soil, and the topsoil is put into the ditch. The topsoil and loose soil layer in the ditch is 40-50cm thick, which can retain water, soil and fertilizer, and is conducive to crop growth.
3.4.2 Human-animal combination
The construction steps are basically the same as manual operation. The difference is that in the steps of taking the topsoil, taking the raw soil, and loosening the bottom of the ditch, livestock are used to bring the plow to loosen the ground soil along the contour line, and then manual work is used to push the topsoil into the ditch to improve work efficiency and save manpower. 3.5 Horizontal furrows in leisure land
3.5.1 In the sloping cultivated land, from top to bottom, every 23m, along the contour line or with a 1% to 2% gradient with the contour line, make a horizontal furrow. When plowing, turn the soil downward to form a soil ridge under the furrow to intercept rainwater. 3.5.2 In order to increase the storage capacity of the furrow, the same position can be plowed twice (two plows) to increase the furrow depth and furrow height. 3.5.3 According to different slopes and rainfall conditions, the spacing between furrows can be increased or decreased. The spacing is smaller in places with steep slopes and heavy rainfall; the spacing is larger in places with gentle slopes and light rainfall.
4 The second type of soil and water conservation farming methodbzxz.net
Combined with farming, the crops planted are reasonably arranged to increase the ground plant cover, especially in the rainy season, the ground is required to have plant cover to reduce water loss and increase crop yields. 4.1 Grass rotation
Applicable to agricultural areas with more land and fewer people or semi-agricultural and semi-pastoral areas. In particular, for areas with the original habit of resting and weeding, grass-field rotation should be adopted instead of resting and weeding to maintain water and soil and improve soil. Different grass-field rotation methods are adopted according to different conditions. 4.1.1 Short-term rotation. Mainly applicable to agricultural areas. After planting crops for 2 to 3 years, plant grass for 1 to 2 years. The grass seeds are mainly short-term green manure and forage grass such as hairy vetch and arrow-tongue pea.
4.1.2 Long-term rotation. Mainly suitable for semi-agricultural and semi-pastoral areas, after planting crops for 4 to 5 years, plant grass for 5 to 6 years. The grass seeds are mainly perennial forage grasses such as first-hunting and Astragalus membranaceus.
4.2 Intercropping and interplanting
Requires two (or more) different crops to be planted simultaneously or successively in the same plot to increase the coverage of the ground and extend the coverage time of the ground, reducing soil erosion. 4.2.1 Intercropping. Two different crops are sown at the same time. The two crops selected for intercropping should have the characteristics of mutual coordination of ecological communities and complementary growth environments, mainly including: reasonable configuration of different crops such as tall-stalked crops and short-stalked crops, deep-rooted crops and shallow-rooted crops, early-maturing crops and late-maturing crops, densely grown crops and sparsely grown crops, light-loving crops and shade-loving crops, gramineous crops and leguminous crops, and planting at the same height. According to the physiological characteristics of crops, the following two intercropping methods are adopted respectively: 4.2.1.1 Intercropping between rows. Appropriately increase the row spacing of the first crop, plant the second crop between every two rows of crops, and keep the spacing between the two crops unchanged.
4.2.1.2 Intercropping between plants. Appropriately increase the plant spacing of the first crop, plant the second crop between every two crops, and keep the row spacing between the two crops unchanged. Double-row intercropping can also be carried out.
4.2.2 Interplanting. In the same plot, in the late growth period of the previous crop, sow or transplant the next crop between its rows or plants. The two crops have different harvesting times, and the requirements for crop configuration coordination and complementarity and plant spacing are the same as intercropping. According to the different characteristics of crops, the following two practices are adopted in terms of sowing time:
4.2.2.1 After the first or second inter-cultivation of the first crop, interplant the second crop. 4.2.2.2 Before the first crop is harvested, interplant the second crop. 4.3 Strip intercropping
4.3.1 Crop strip intercropping:
4.3.1.1 See 4.2.1 for intercropping crop types. 4.3.1.2 The direction of the intercropping strip is basically along the contour line, or maintains a gradient of 1% to 2% with the contour line. 4.3.1.3 The strip width is generally 5 to 10m. The two crops can be of equal width or different widths. The strip width is smaller on steep slopes and larger on gentle slopes.
4.3.1.4 The different crops on the above strips are interchanged every year or every 2-3 years, forming strip intercropping and rotation. 4.3.2 Grass-grain strip intercropping:
4.3.2.1 The intercropped crops and grasses can refer to 4.1.1 and 4.1.2. 4.3.2.2 The direction of the strip is basically along the contour line, or with a gradient of 1% to 2% with the contour line. 4.3.2.3 The width of the strip is generally 5 to 10 meters. The width of the crop strip and the grass strip shall be in different proportions under different circumstances: in general, the two can be equal in width; in areas with more land and fewer people and steeper slopes, the width of the grass strip can be larger than the width of the crop strip; in areas with less land and more people and gentler slopes, the width of the grass strip can be smaller than the width of the crop strip.
4.3.2.4 Swap the grass strip and the crop strip every 2-3 years or 5-6 years to form a grass-grain strip intercropping and a grass-grain rotation. However, the width of the strip needs to be adjusted after the swap so that the grass strip and the crop strip maintain the original width ratio. 4.4 Planting green manure on fallow land
Applicable to arid and semi-arid areas, where the ground is fallow for dozens of days after the summer crop is harvested (this is the rainy season). The method is as follows:
4.4.1 10-15 days before the crop is harvested, sow green manure plants on the ground along the contour line between the crop rows; after the crop is harvested, the green manure plants grow faster and quickly cover the ground.
4.4.2 After the rainy season, turn the green manure into the soil or harvest it as forage. It is required that the ground is covered with grass throughout the rainy season. 4.4.3 If for some reason it is not possible to interplant green manure before the crop is harvested, it should be sown as soon as possible after the crop is harvested, and horizontal furrows should be made in coordination. 4.5 Reasonable close planting
Applicable to areas with extensive farming and low crop plant density. By selecting excellent varieties, increasing fertilizers, intensive farming, and implementing intensive management, combined with contour farming, the plant density of crops can be reasonably adjusted and increased to conserve water, soil, and fertilizer, and increase crop yields. Different practices are adopted under different conditions:
4.5.1 In areas with good water and fertilizer conditions, the plant density of crops can be greatly increased, and the spacing between plants and rows can be reduced at the same time, or the spacing between plants can be reduced while the row spacing remains unchanged, or the spacing between plants can be reduced while the row spacing remains unchanged.
4.5.2 In areas with poor water and fertilizer conditions, the row spacing can be appropriately increased and the spacing between plants can be reduced along the contour lines, and wide rows and close planting can be implemented to maintain an appropriate increase in the total number of plants in the field, which is conducive to water and soil conservation, and can adapt to lower water and fertilizer conditions. 5. The third type of soil and water conservation farming method
Combined with farming, it adopts methods to change the physical and chemical properties of the soil, increase soil infiltration, improve soil erosion resistance, and reduce soil erosion.1 Deep ploughing and loosening
The depth of ploughing and loosening is based on the principle of breaking the plow bottom layer and improving the soil infiltration capacity, generally 25 to 30 cm. 5.2 Increased application of organic fertilizer
Required to promote the formation of soil granular structure, improve the water holding capacity and soil erosion resistance, 5.3 Stubble sowing
Applicable to sloping cultivated land or gently sloping wind erosion land where two crops cannot be interplanted in the same plot. Field
Part II Terrace
6 Scope
This part stipulates the classification of terraces on sloping cultivated land and the planning, design, construction, management and other technologies of various types of terraces. This part is applicable to water erosion areas and areas where water erosion and wind erosion are interlaced throughout the country. 7 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T16453.4-1996 Technical Specification for Comprehensive Management of Soil and Water Conservation Small-scale Water Storage, Drainage and Diversion Project 8 Basic Provisions
8.1 Classification of Terraces
8.1.1 According to the different ground slopes, terraces are divided into steep slope area terraces and gentle slope area terraces. 8.1.2 According to the different building materials of the field ridges, they are divided into earth ridge terraces and stone ridge terraces. 8.1.3 According to the different cross-sectional forms of the terraces, they are divided into horizontal terraces, slope terraces, and slope terraces, see Figure 2g
Horizontal tree terraces
Slope terraces
Slope terraces
Figure 2 Schematic diagram of the cross-sectional areas of three types of terraces
8.1.4 According to the different uses of the terraces, they are divided into dry crop terraces, rice terraces, orchard terraces, tea garden terraces, rubber garden terraces, etc. 8.2 Take small watersheds as units to carry out comprehensive planning for the management of sloping cultivated land. According to different conditions, terraces, soil conservation farming methods and small-scale slope storage and drainage projects shall be adopted respectively. For the sections determined as terraced areas, specific planning for terraces shall be carried out; on this basis, corresponding design and construction shall be carried out.
8.3 When the slope above the terraced area is sloping cultivated land or wasteland, small-scale slope storage and drainage projects shall be deployed to prevent surface runoff from entering the terraced area. In the southern areas of my country with heavy rainfall, small-scale storage and drainage projects should also be deployed in the terraced areas to properly handle the rainwater that the terraces cannot store and ensure the safety of the terraces. The technical requirements for small-scale slope storage and drainage projects shall be implemented in accordance with GB/T16453.4. The standard for terraced fields to defend against rainstorms generally adopts the maximum rainfall of 3 to 6 hours once in 10 years. In arid, semi-arid or other areas with little rainfall, the maximum rainfall of 3 to 6 hours once in 20 years can be adopted. According to the rainfall characteristics of various places, short-duration and high-intensity rainstorms that are most likely to cause serious soil erosion are adopted respectively. 8.4 Selection of terrace types
8.4.1 For areas with thick soil layers on sloping farmland and abundant local labor, horizontal terraces should be built at one time as much as possible. 8.4.2 For areas with thin soil layers on sloping farmland or less local labor, slope terraces can be built first, and the slope of the field can be reduced by turning the soil downward year by year, gradually turning it into horizontal terraces.
8.4.3 In areas with a large population and a lack of labor, and with less annual rainfall and a farmland slope of 15° to 20°, slope terraces can be used to plant crops on the platform part and plant pasture on the slope part; during heavy rains, surface runoff on the slope part can be used to increase soil moisture on the platform part. 8.4.4 In general soil hills and plateaus and terraces, earthen terraces should be built. In soil and rocky mountainous areas or rocky mountainous areas, if there are a lot of stones and gravel in the sloping farmland, when building terraces, stones and gravel in the ground should be processed and local materials should be used to build stone terraces. 8.4.5 Sloping farmland in hilly or mountainous areas (slope is generally 15°～25°) shall be planned and designed as terraces in steep slope areas. Gentle slope farmland in the Northeast Black Soil Hilly Area and Northwest Loess Plateau Area, as well as scattered river valley terraces (slope is generally below 3°, and a few can reach 5°～8°), shall be planned and designed as terraces in gentle slope areas. 9 Planning
9.1 Planning of terraces in steep slope areas
9.1.1 Choose places with good soil quality, relatively gentle slope, close to the village, convenient transportation, low location, and close to water sources to build terraces. If conditions permit, small-scale mechanical farming and water lifting irrigation should be considered. 9.1.2 There must be a road from the foot of the slope to the top of the slope and from the village to the field. The road surface is generally 2 to 3 meters wide and the gradient does not exceed 15%. In places where the ground slope exceeds 15%, the road adopts an "S" shape, winding up to reduce the maximum gradient of the road surface. 9.1.3 The layout of the fields should follow the terrain of the hillside, with large bends following the terrain and small bends being straightened. The length of the fields should be as long as possible between 100 and 200 meters to facilitate farming. 9.1.4 Where the terraced area cannot completely intercept and store rainstorm runoff, corresponding drainage and storage projects should be arranged; where surface runoff enters the terraced area from the upper part of the hill, small storage and drainage projects such as intercepting ditches should be arranged to ensure the safety of the terraced area. 9.2 Planning of terraces in gentle slope areas
9.2.1 The farming area is divided with roads as the framework, and terraces with wide surfaces (20 to 30 meters or wider) and low ridges (about 1 meter) are arranged in the farming area: the field length is 200 to 400 meters, which is convenient for large-scale mechanical farming and gravity irrigation. 9.2.2 In general, the farming area is rectangular or square, with access roads on four or three sides, the road surface is about 3 meters wide, and the roadside is combined with channels and farmland shelterbelt networks; both ends of the farming area road are connected to village, township and county roads. 9.2.3 For a few areas with undulating terrain, the farming area should be fan-shaped in accordance with the overall terrain, and the terrace lines in the area should also be slightly curved, and are not required to be straight lines.
10 Design
10.1 Cross-sectional design of horizontal terraces
10.1.1 Cross-sectional design of horizontal terraces requires the optimization of terrace sections under different slopes. The field surface should have an appropriate width (generally 5 to 15m in steep slope areas and 20 to 40m in gentle slope areas). The slope of the ridge is appropriate, which is both solid and stable, and does not occupy too much arable land. 10.1.2 Cross-sectional elements of horizontal terraces
10.1.2.1 Cross-sectional elements of horizontal terraces are shown in Figure 3. 0 Original ground slope, (°); α - slope of terrace ridge, (°): H - height of terrace ridge, m; Bx - original slope width, m: Bm - gross width of terrace surface, m: B - net width of terrace surface, m; b - width of terrace ridge, m Figure 3 Water Elements of terraced field section
10.1.2.2 Relationship between elements:
Ridge height
Original slope width
Ridge width
Field gross width
Ridge height
Field net width
H=B,sino
B=Hcose
b=Hctga
Bm=Hctgo ..
H=Btang
B=Bb=H(ctg-ctga)
（4）
10.1.2.3 In addition to the above elements, there should be water storage on the edge of the field, with a height of 0.3~0.5m, a top width of 0.3~0.5m, and an inner and outer slope ratio of about 1:1; in the rainy areas in southern my country, there should be drainage ditches on the inside of the terraces, and their specific dimensions are determined according to the rainfall, soil quality, and surface runoff conditions in various places. The required earthwork volume is calculated based on the cross-section dimensions and is not included in the design of the above elements. 10.1.3 The reference values of the main dimensions of the horizontal terrace sections are shown in Appendix A (Suggested Appendix). 10.1.4 Calculation of horizontal terrace engineering quantity: 10.1.4.1 Calculation of earthwork volume per unit area: V = (1/2) ((B/2) × (H/2) × L) = 1/8BHL Wherein: V -
earthwork volume per unit area (hectare or mu), m3; length of terrace per unit area (hectare or mu), m; height of field ridge, m;
net width of field surface, m.
When the terrace area is calculated in hectares:
V=（1/8）HX104=1250H
（7）
（8）
When the terrace area is calculated in mu:
10.1.4.2 Calculation of earthwork transfer volume per unit area: V=（1/8）HX666.7=83.3H.
W=V×2/3B=1/12B2HL
Where: W—earthwork transfer volume per unit area (hectare or mu), m3-m. The unit of earthwork transport volume is m3-m, which is a composite unit, that is, several cubic meters of earthwork need to be transported for several meters. When the terrace area is calculated by hectare:
W=（BH/12）×104=833.3BH
W——Earthwork transport volume per hectare, m3-m. When the terrace area is calculated by mu:
W=（BH/12）X666.7=55.6BH.
W——Earthwork transport volume per mu, m3-m10.2 Cross-section design of slope terraces
10.2.1 Determine the spacing between contour trenches
10.2.1.1 The slope field surface B between every two trenches should be wide enough to meet the needs of farming. (10)
(11))
(12)
10.2.1.2 According to the ground slope, (generally, the steeper the ground slope, the smaller the trench spacing; the gentler the ground slope, the larger the trench spacing. 10.2.1.3 According to the rainfall conditions in the region, generally the trench spacing should be smaller in areas with heavy rainfall and intensity, and larger in areas with light rainfall and intensity.
10.2.1.4 According to the soil conditions of the cultivated land, generally the trench spacing should be larger if the soil particles contain more sand and have stronger permeability; the trench spacing should be smaller if the soil is heavy and has poor permeability. 10.2.1.5 Different regions should follow the above different conditions, After comprehensive analysis, determine the spacing between trenches and burials. At the same time, refer to the B value of the local horizontal terrace section design, and consider that the cross-section of the sloped terrace after increasing soil burial year by year, and finally becomes a horizontal terrace, should be similar to the cross-section of the horizontal terrace built in one go.
10.2.2 Determine the cross-section size of the contour trench
10.2.2.1 The basic form of trench burial should be buried on top and trench on the bottom, dig trenches from the bottom to take soil, and bury on top of the trench, so as to facilitate the gradual increase of soil burial year by year, so as to gradually reduce the slope of the field surface and eventually become a horizontal terrace. 10.2.2.2 Top width 3 0～40cm, height 50～60cm, outer slope 1:0.5, inner slope 1:1. 10.2.2.3 Through the calculation of rainfall-runoff-sediment, the capacity above the buried soil in arid and semi-arid areas is required to be able to intercept the surface runoff and sediment generated on the slope between the two buried soils during a rainfall event that occurs once every 10 to 20 years. In rainy areas where the buried soil cannot intercept all the runoff and sediment, it should be combined with a small slope storage and drainage project to properly handle the excess runoff and sediment (for slope runoff and sediment calculation, refer to 4.1.2 in GB/T16453.4). 10.2.2.4 When the soil above is due to sediment When the capacity is reduced due to siltation, soil should be taken from below and raised in time to maintain the initial size and capacity.
10.2.3 Cross section of slope terrace (see Figure 4)
Figure 4 Cross section of slope terrace
10.2.4 Cross section design of grass belt (or shrub belt) slope terrace a) The width of the slope field between each two belts shall be determined in accordance with the requirements of 10.2.1; b) The width of the grass belt (or shrub belt) is generally 3 to 4 meters: c) Before planting the grass belt (or shrub belt), a wide shallow soft (not compacted) soil can be first built and the grass (or shrub) can be planted on top, see Figure 5. Figure 5 Grass belt (shrub belt) slope terrace
10.3 Cross section design of slope terrace
10.3.1 The main task of cross section design of slope terrace is to determine the width of the slope part and the horizontal part of the terrace and the relative proportion between the two. 10.3.2 Determine the width of the platform
10.3.2.1 According to the ground slope (15°～25°) that the terraced fields are adapted to, the horizontal field width is generally 5～10m. It can be wider for gentle slopes and narrower for steep slopes.
10.3.2.2 The width of the platform is required to be able to adapt to both farming and the storm runoff on the slope (it is required to be able to intercept all slope runoff: at the same time, interception can effectively increase crop yields) 10.3.3 Determine the width of the slope
10.3.3.1 The width of the slope (measured by vertical projection) is expressed as the ratio of its width to the horizontal part. If the horizontal field width is 1, then the slope part
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