CN102392453A - Terrace bank construction method for changing slope farmland into level terrace in reservoir area of Three Gorges - Google Patents

Abstract

The invention discloses a terrace bank construction method for changing slope farmland into level terraces in the reservoir area of the Three Gorges. The slope farmland consists of a plurality of transversely-partitioned cultivation units; a terrace bank for soil reinforcement walking is built on the outer side of every cultivation unit; all terrace banks include stone banks and soil banks; the soil banks are always arranged between every two stone banks; the terrace bank on the outer side of the cultivation unit on the bottommost layer of a slope surface is a stone bank; every cultivation unit is cultivated by keeping the original slope farmland micro-topographic feature; and the soil banks are positioned on the outer edges of the original cultivation units. The method has the advantages of reduction in the cost investment, convenience for agricultural cultivation, good water and soil conservation effect and easy acceptance by farmers.

Description

Construction Method of Slope to Terrace Ridge in the Three Gorges Reservoir Area

technical field

The invention relates to water and soil conservation technology, and specifically refers to a ridge construction method for converting slopes into terraces on sloping farmland in the Three Gorges Reservoir area. This method can reduce construction costs compared with horizontal terraced land with stone ridges, and has better water and soil conservation effects than building all stone ridges. It is more ecological and belongs to the technical field of water and soil conservation.

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Background technique

my country's natural conditions are complex, with large areas of mountains and hills, and the per capita arable land area is only 1.38 mu, which is less than 40% of the world average. Especially in the Three Gorges Reservoir area, the per capita arable land area is only 0.81 mu. The existing arable land resources are mainly sloping farmland, and the area of sloping arable land above 15° accounts for 47.6% of the total arable land area. It is an important carrier of grain and economic crops in the reservoir area. At the same time, slope farmland is considered to be the main source of soil erosion and sediment in the Three Gorges Reservoir area. The average erosion modulus of sloping cultivated land in the Three Gorges Reservoir area is 7500 tons per square kilometer. 46.16% of the total annual sediment storage in the district.

The management of sloping farmland has been the focus of soil and water conservation work in recent decades. Slope-to-terrace conversion (its main form is to transform sloping cultivated land into stone ridge level terraced land) is an important method used in soil and water conservation projects at present, and it is also an effective measure to control sloped farmland and build basic farmland in mountainous areas. By changing the length of the slope and intercepting runoff in sections, the slope-to-ladder project increases the infiltration time of the soil and slows down the flow velocity of the surface runoff, effectively preventing and reducing the scouring effect of the runoff on the surface soil, and can also transfer the intercepted precipitation from slope water to Deep soil water or groundwater, improve the drought resistance of crops. According to the survey, the soil loss of horizontal terraced land is about 97% lower than that of sloping farmland, the content of soil organic matter is increased by 16.6%, and the content of total nitrogen is increased by 21.4%.

However, the proportion of sloping farmland in the Three Gorges Reservoir area is large and the slope is steep, so it is difficult to build all the sloping farmland into horizontal terraced land with stone ridges. First, the farmers accept the aspect. In the low mountain and shallow hilly area, the slope of the slope farmland is small and the slope is long. The stone ridge terraces effectively integrate the slope farmland, and the benefits of soil conservation and sand reduction are obvious, which not only effectively improves the local agricultural production conditions and ecological environment, but also promotes the development of the rural economy. development, farmers are easy to accept. However, as far as the middle and high mountainous areas are concerned, the sloping cultivated land has a large slope, a steep slope, and a short slope length. The conversion of stone ridges to terraces brings some inconvenience to agricultural production. Usually, the height of stone ridges is about 1 to 2 meters, which is not convenient for farmers to cultivate and Livestock walk. Terraced ridges occupy a lot of land (7% to 12%), which makes the cultivated land resources more tense, which is difficult for farmers to accept. Farmers in some districts and counties would rather abandon the horizontal terraced land of stone ridges and choose steep slopes for planting. Second, cost input. According to the survey, the construction of horizontal terraces requires a large amount of engineering (3000-6000 m ³ /hm ² ), high cost (30,000-100,000 yuan/hm ² , excluding supporting investment in slope water system), and requires a lot of manpower Material input is difficult to realize under the background of massive transfer of rural labor force in the Three Gorges Reservoir area. To sum up, although the stone ridge horizontal terraced land has a standard layout, regular shape, and obvious benefits of sand reduction, it is not the optimal form of changing slopes to terraces in the Three Gorges Reservoir area. How to find a slope farmland that is more suitable for the Three Gorges Reservoir area and is easy for farmers to accept Retrofitting the way of utilization is an urgent problem to be solved by soil and water conservation experts and local governments.

Contents of the invention

Aiming at the above-mentioned deficiencies in the existing sloping land rectification technology, the purpose of the present invention is to provide a construction method for the Three Gorges Reservoir Area of the Three Gorges Reservoir Area, which reduces the cost input, facilitates agricultural cultivation, has better water and soil conservation effects, and is easier for farmers to accept.

The technical scheme of the present invention is realized in the following way: the construction method of the slopes of the Three Gorges Reservoir area to terrace ridges, the sloping cultivated land is composed of several horizontally divided farming units, and the outer side of each farming unit is built to fix the soil and walk the ridges, and all the ridges There are both stone ridges and soil ridges, and there is always an earth ridge between the two stone ridges. The ridge outside the bottommost farming unit on the slope is a stone ridge, and each farming unit maintains the original micro-geomorphology of slope farmland for farming.

Furthermore, drainage holes are arranged along different heights on the stone ridge wall according to local conditions, so as to enhance the drainage capacity in rainy seasons and avoid damage to the stone ridge caused by heavy rainfall runoff. On the inner wall of the ridge, build side ditches and back ditches for interception to prevent runoff from scouring the ridge.

The layout positions of the ridges are all located on the outer edge of the original farming unit, so there is no need to re-divide the original farming unit, and the original micro-topography of the plot is maintained. With the farming activities year by year, the plowing of the land gradually increases the slope. Slowing down and reducing the amount of engineering in the rectification process can properly save costs and be more acceptable to farmers.

Considering the relative stability of the stone ridge, the longitudinal section of the stone ridge is rectangular, which can reduce the occupied area and save land resources. Since the stability of the ridge is not as good as that of the stone ridge, the longitudinal section of the ridge is built as a right-angled trapezoid to enhance the stability of the ridge. The ridge can be planted with dwarf economic crops, which improves the land utilization rate and is also convenient for farmers to move between two adjacent plots. Walk up and down.

Economic hedgerows are planted on the ridge, and the hedgerows can further consolidate the soil. It is also possible to directly plant contour economic hedgerows at the ridge position without setting up the ridge, which can also play a role in maintaining the soil, and can also improve land utilization and increase output.

The building materials for ridge ridges should be obtained locally and nearby, and the building materials for stone ridges can be stone or hollow bricks.

Compared with the existing "slope to terrace" (horizontal stone sill terrace) water and soil conservation and corresponding farming methods, this method has the following effects:

1) According to the investigation and research in the Three Gorges Reservoir area, the erosion modulus of ridge slopes to terraces is 555 tons/km2, and the erosion modulus of stone ridges to terraces is 26 tons/km2. The soil erosion modulus of the layout pattern of + stone ridges is less than the allowable loss of 500 tons per square kilometer per year, which can meet the requirements of water and soil conservation.

2) Because there are earth ridges in the middle of the rock ridge, the construction cost of the earth ridge is less than that of the stone ridge, so the overall cost is reduced.

3) Low economic crops can be planted on the ridge, which virtually increases the working area and land utilization rate, and avoids the defects of inability to plant and high land occupation rate caused by the original stone ridge with a single layout of terraces.

4) In this method, the farming units do not need to be organized into horizontal terraces, but maintain the original micro-geomorphology of sloping farmland. In the later farming activities, farmers plow the land year by year, and the slope gradually slows down. It not only conforms to the farming habits of farmers, but also complies with the needs of the local rainy season for draining water, and greatly reduces the cost of renovation. Surveys in the Three Gorges Reservoir area also show that the operation of "slope-to-terrace" fields in middle and high mountainous areas is not very convenient, and farmers do not welcome them. However, the sloping farmland transformed by this method is convenient for farmers to produce, the cultivation efficiency is enhanced, and the water and fertilizer utilization rate is improved. easy to accept.

In short, compared with the existing stone ridge horizontal terraces, this method has lower cost and simple operation. Reasonable planting of economic hedgerows can not only stabilize the soil but also improve economic benefits. Ecological, suitable for promotion in middle and high mountainous areas.

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Description of drawings

Figure 1 - a schematic front view of an embodiment of the present invention.

Figure 2-Figure 1 side schematic view.

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Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

The method for constructing ridges from slopes to terraces in the Three Gorges reservoir area of the present invention, the sloping cultivated land is composed of a plurality of horizontally divided farming units, and a ridge for solid soil walking is built on the outside of each farming unit. In this method, there are both stone ridges and earth ridges in the ridge, and there is always an earth ridge between the two stone ridges, forming a mixed mode of "rock ridge + earth ridge" interval, and based on the stability requirements of the ridge, (the bottom of the slope) The ridges outside the next level of farming units are always constructed as stone ridges. Ridges are configured according to slope and slope length and thresholds for rill erosion to occur. The construction materials of the stone sill can be block stone, gravel, (hollow) bricks, etc. During the construction process, drainage holes are evenly arranged along different heights on the stone sill wall to enhance the drainage capacity in the rainy season and avoid damage to the stone sill by heavy rainfall runoff. At the same time, side ditches and back ditches for interception are built on the inner wall of the ridge to prevent runoff from scouring the ridge. In the present invention, earth ridges are arranged in the middle of the stone ridges, and the construction cost of the earth ridges is less than that of the stone ridges, so the cost is reduced. It is sufficient for each farming unit to maintain the original micro-geomorphology of sloping farmland for farming, without flattening to form horizontal terraces, which can further reduce the transformation cost.

The layout positions of the ridges are all located on the outer edge of the original farming unit, and the field surface remains the same in principle, so that the original farming unit does not need to be re-divided, and the original micro-topography of the plot can be maintained. In the later farming activities, Farmers plow the land year by year, and the slope gradually slows down. It is easier to be accepted by farmers, and at the same time, it can save costs appropriately.

Considering the relative stability of the stone ridge, the longitudinal section of the stone ridge is rectangular, which can reduce the occupied area and save land resources. Since the stability of the ridge is not as good as that of the stone ridge, the longitudinal section of the ridge is built as a right-angled trapezoid to enhance the stability of the ridge. Economic hedgerows can be planted on the ridge, which can not only improve the land utilization rate, but also play a role in consolidating the soil. It is also convenient for farmers to walk up and down between two adjacent plots.

Dwarf cash crops are usually planted on the ridges and slopes of the ridges, and the cash crops are selected according to local conditions such as farmers' preferences, market demand and site conditions. The hedgerows are used to further consolidate the soil ridges, enhance soil erosion resistance, and increase economic income at the same time. When the slope is small (below 8°), it is also possible not to build a ridge, and directly plant a contour economic hedgerow at the ridge position, which can also play a role in maintaining the soil, and can also improve land utilization and increase output.

When this method is implemented, the sloping cultivated land is divided into three situations according to the slope: below 8°, 8°~15°, and 15°~25°. Since the slope above 25° is the area for returning farmland to forest, it is not suitable as cultivated land. are not considered in this method. At the same time, due to the large runoff at the foot of the slope, the erosion is the most serious, and the probability of collapse is relatively high, and the stability of the stone ridge is greater than that of the earth ridge, so the stone ridge is always built at the foot of the slope. (Plant hedge) The number of ridges and stone ridges can be flexibly determined according to the critical value of rill erosion, slope, slope length and farming needs. For details, refer to the recommended methods in Table 1.

Table 1 Recommended ridge construction methods for this method

The arrangement method of the marked rock ridges and earth ridges in the table is a bottom-up layout method, and the above stone ridges and earth ridges are respectively one. If the original ground slope length is not within the above range, it can be configured separately according to the excess length.

Fig. 1 and Fig. 2 are the concrete embodiment that two road ridges 2 are built between two stone ridges 1. l ₁ is the original ground slope length between stone ridges, and l ₂ is the original ground slope length between earth ridges.

The construction method of changing slopes into terraces, ridges and ridges proposed by the present invention has an effect close to that of horizontal terraces. The widely used horizontal terraces of stone ridges are transformed into alternate layouts of stone ridges and earth ridges, and part of the stone ridges are changed into earth ridges, maintaining the original slope. Farming with micro-geomorphology without flattening slope farmland, the construction of slope water system is basically similar to the existing slope-to-ladder construction method, which is suitable for promotion in hilly areas, especially the Three Gorges Reservoir area.

Claims (5)

1. The method of constructing ridges from slopes to terraces in the Three Gorges Reservoir area. The sloping farmland is composed of several horizontally divided farming units, and ridges are built on the outside of each farming unit to fix the soil. There is a ridge, and there is always a ridge between the two rock ridges, and the ridge outside the lowest level of farming unit is a rock ridge, and each farming unit maintains the original micro-geomorphology of slope farmland. 2. The method for constructing ridges from slopes to terraces in the Three Gorges reservoir area according to claim 1, characterized in that: the walls of the stone ridges are provided with drainage holes for permeable water at different heights, and the inner walls of the ridges are built with edges for interception ditch back ditch. 3. The method for constructing slope-to-terrace ridges in the Three Gorges reservoir area according to claim 1 or 2, characterized in that: the setting positions of the earth ridges are all located at the outer edges of the originally formed farming units. 4. The method for constructing slope-to-terrace ridges in the Three Gorges reservoir area according to claim 3, characterized in that: the longitudinal section of the stone ridge is rectangular, and the longitudinal section of the ridge is right-angled trapezoidal. 5. The method for constructing slope-to-terrace ridges in the Three Gorges Reservoir area according to claim 3, characterized in that economical hedgerows are planted on the ridges or economical hedgerows are planted directly at the positions of the ridges without repairing the ridges.

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