CN101790931B - A method for restoring damaged ecosystems in steep slope areas of reservoir drawdown zones - Google Patents

Abstract

The invention relates to a method for restoring a damaged ecosystem in a steep slope area of a water-fluctuation zone of a reservoir. When the storage water level is the lowest, clean up the slope facing the water-fluctuating zone and compact it manually; excavate planting holes at the top of the slope and plant masson pine, etc., to form a multi-functional shelterbelt. Dig planting grooves and planting holes within the water-fluctuating zone, lay jute geotextiles, and plant vetiver within the water-fluctuating depth of 2m to form a plant hedge. Vetiver and Bermudagrass are planted mixedly in the range between 2-10m to form a composite vegetation slope restoration zone. The protection forest belt, the hedgerow belt and the composite vegetation slope restoration belt of the present invention together form a three-dimensional restoration space, which ensures that plants take root and restore on the steep slope area of the water-fluctuation zone. Through large-scale restoration of vegetation, surface runoff and soil erosion can be effectively reduced, soil fertility and properties can be improved, and damaged ecosystems can be restored. The invention has the advantages of convenient construction, small investment, and is not easy to be destroyed by water, and is suitable for areas in the water-fluctuation zone of reservoirs with large water-fluctuation range and steep terrain.

Description

A method for restoring damaged ecosystems in steep slope areas of reservoir drawdown zones

technical field

The invention relates to a method for restoring a damaged ecosystem in a steep slope area of a water-fluctuation zone of a reservoir.

Background technique

Danjiangkou Reservoir is the water source of the middle route project of "South-to-North Water Diversion". It is located at the confluence of Han River and Dan River. The initial project of Danjiangkou Reservoir was completed in 1973. The normal storage level is 157m, the restricted water level for flood control in summer is 149m, and the area of the water-fluctuating zone is 148km ² . After the second phase of the dam heightening project was completed in 2011, the normal water storage level reached 170m. The reservoir dispatching will begin to store water at the end of the flood season in October every year, and the water level will rise to 170m in December; in May of the following year, the water level will gradually decrease from 170m to the flood control limit water level, and the water level will remain at 160-163.5m during the flood season. The new water-fluctuation zone will be moved up to the bank bank at an altitude of 160-170m, with an area of about 205km ² . The quality of the vegetation in the hydrofluctuation zone is an important indicator of the healthy operation of the reservoir, and it also plays an important role in the river ecosystem. However, due to reservoir adjustment and storage operation and natural conditions, the water level of the reservoir frequently fluctuates greatly and the submersion time is too long, and the vegetation on the edge of the reservoir is easily damaged, especially in some areas with steep slopes, rapid water flow and poor soil. Vegetation may be submerged and disappear, which means that the Danjiangkou reservoir area has lost an ecological barrier, and various ecological and environmental problems such as increased pollution, increased soil erosion, and frequent geological disasters will appear in the water-fluctuating zone, which threatens the sustainable use of the reservoir and the reservoir quality. A virtuous cycle of the regional ecosystem. Plant ecological restoration of the damaged ecosystem in the water-fluctuating zone is one of the most effective treatment methods considered by experts at home and abroad. The technology of vegetation protection in the water-fluctuating zone of the reservoir is a major problem. The main difficulties lie in: ① The scope of the water-fluctuating zone The soil is vulnerable to water erosion and loss, and the basic conditions for plant growth are constantly being destroyed; ②The ecological environment in the water-fluctuating zone is harsh, and plants have to endure the adverse effects of deep water, low temperature, lack of fertilizers, and floods for a long time; ③Operation characteristics of the reservoir project The vegetation in the stable-type water-fluctuation zone cannot be simply rebuilt on the new water-fluctuation zone.

At present, the ecological restoration of the water-fluctuating zones of some relatively large-scale hydropower projects has begun to improve the biodiversity and environmental conditions in the reservoir area. For example, "A New Type of Plant Configuration and Ecological Engineering Technology for Anti-scour and Bank Protection of Embankments and Reservoirs" (Chinese Patent Application No. 03146885.3), it is a kind of vetiver as the main body, and then configures other plant materials. , Technical design, seedling selection and breeding, construction and planting, professional maintenance management, ecological engineering technology used for anti-scour and revetment of embankments and reservoirs. "A Wetland Treatment Method for Improving the Ecological Environment of the Reservoir's Fluctuation Area" (Chinese Patent Application No. 200910099098.X), the excavation area is excavated, the filling area is filled, and the top of the excavated filling body Protect the water surface and the water surface, plant submerged plants and floating leaf submerged plants in the area between the sinking depth of 3-5m, and plant emergent plants and hygroscopic trees and shrubs in the area within the sinking depth of 3m. "The Method for Restoring Reservoir Fluctuation Zone and Riverbank Damaged Ecosystem with Bermudagrass" (Chinese Patent Application No. 200810032895.1), screens Bermudagrass as a restoration plant, adopts asexual reproduction or sexual reproduction to plant or transplant to the restoration area, and then Carry out maintenance to ensure growth in the coming year, thereby rebuilding and restoring the ecology of the sink-fluctuation zone and the riparian zone.

The hydrofluctuation zone in the Danjiangkou Reservoir area will be submerged seasonally after impoundment, and some places will be flooded for 6 months, with a 10m water level drop during the period. The water level should be resistant to drought and poor soil when the water level drops, and can withstand long-term submersion after the water level rises. Amphibians are extremely important for restoration of the water-fluctuation zone. At the same time, part of the water-fluctuating zone in the Danjiangkou Reservoir area has steep slopes, rapid water flow, poor soil, and poor site conditions. Direct planting requires insufficient water and fertilizers, and serious slope erosion makes it difficult for vegetation to grow and survive. Some effective auxiliary measures. At the same time, the interception and filtering functions of vegetation on water and soil loss from reservoir banks and agricultural non-point source pollution should also be considered, and proper configuration should be made. In summary, none of the above inventions is suitable for use in this region.

Contents of the invention

The purpose of the present invention is to address the above-mentioned current situation, aiming to provide a reservoir fading that is convenient in construction, small in investment, wide in application, not easily destroyed by water, good in effect, and can meet the requirements of effective water and soil conservation and pollution control in the Danjiangkou Reservoir's fading zone. Restoration of damaged ecosystems in areas with steep slopes.

The way to achieve the object of the present invention is a method for restoring the damaged ecosystem in the steep slope area of the reservoir drawdown zone, the specific steps are as follows:

1) Choose to repair and level the facing slope of the water-fluctuation zone when the storage water level is the lowest, clean up stones, weeds, garbage, and perform appropriate manual compaction;

2) Excavate planting holes at the top of the outer slope of the water-fluctuation zone by means of fish-scale pit preparation, and plant masson pine or other suitable tree species in the planting holes;

3) In the area within 2m of sinking depth, excavate planting troughs along the horizontal contour strip-shaped soil preparation method, and excavate planting holes in the area of sinking depth 2-10m in the form of pits and fish scale pits. The area outside the acupoint is planted with bermudagrass by cutting the stem and withdrawing pressure;

4) Lay a layer of jute geotextile along the water-facing slope of the water-fluctuation zone, and the upper and lower ends of the jute geotextile are fixed in the soil foundation with U-shaped anchors;

5) Transplant vetiver in the planting grooves within the area of the water level within 2m, and in the planting hole of the area between the water level of 2-10m;

6) Timely irrigate fixed root water;

7) Routine care.

The present invention adopts the jute geotextile with multifunctional ecological benefits to protect the slope. The jute geotextile is a biodegradable open mesh fabric woven from low-grade jute raw materials and hemp spinning waste. A new type of material for controlling slope erosion can provide a stable growth environment for plants while preventing soil erosion, and promote the survival, growth and development of plants on slopes.

According to the invention, suitable tree species such as masson pine are planted on the top of the slope to form a multi-functional protective forest with the functions of maintaining water and soil, conserving water sources, and improving water quality; densely planting vetiver at the upper end of the water-fluctuating zone area to form a vetiver hedgerow, which can Improve soil fertility and soil properties, effectively reduce surface runoff and soil erosion; plant vetiver and bermudagrass in the area below the vetiver hedgerow in the water-fluctuation zone, and make full use of the well-developed root system of vetiver and its ability to protect slopes and soil The strong characteristics and the rapid expansion and spread of bermudagrass stolons and rhizomes form a composite vegetation slope restoration zone. The protection forest belt, the hedgerow belt and the composite vegetation slope restoration belt of the present invention together form a three-dimensional restoration space, which ensures that plants take root and restore on the steep slope area of the water-fluctuation zone. By restoring vegetation on a large scale, improving soil fertility and soil properties in water-fluctuating zones, effectively reducing surface runoff and soil erosion, intercepting and filtering agricultural non-point source pollution, and achieving the purpose of restoring damaged ecosystems.

The invention has the advantages of convenient construction, small investment, wide applicability, not easy to be destroyed by water, good effect, and is suitable for water and soil conservation and pollution control in reservoir water-fluctuation zone areas with large water-fluctuation range and steep terrain.

Description of drawings

Figure 1 is the front view of the vegetation restoration structure on the slope of the water-fluctuating zone.

Fig. 2 is a side view of the vegetation restoration structure on the slope of the hydrofluctuation zone.

Detailed ways

The present invention is aimed at the steep slope area of the drawdown zone of the Danjiangkou Reservoir, where the slope is relatively large, the soil is barren, and the site conditions are poor. Especially after the reservoir is adjusted and stored, the water level fluctuates frequently and greatly and the submerged time is too long, which makes the vegetation on the edge of the reservoir vulnerable to damage. It is a method invented for the situation that it is destroyed and difficult to grow, further causing soil erosion and pollution aggravation, and unable to achieve ecological restoration.

Referring to Fig. 1, 2 below, the present invention is described in detail with the steep slope area of the water-fluctuating zone of Danjiangkou Reservoir as an example.

The specific steps to restore the damaged ecosystem in the steep slope area of the water-fluctuation zone are as follows:

1) The water level of Danjiangkou Reservoir is the lowest in May, so May is chosen to repair and level the facing slope of the water-fluctuation zone, clean up stones, weeds, and garbage, and perform appropriate manual compaction. In the figure, the lower line is the summer flood limit water level 8, and the upper line is the normal water storage level 9.

2) On the top of the outer slope of the water-fluctuation area, that is, the area above the water level of 170m, excavate planting holes by means of fish-scale pit preparation. The planting holes on the top of the outer slope of the sinking area are 50-80cm wide, 70-100cm long, 40-60cm deep, and 200-300cm apart. When excavating the planting hole, the topsoil is piled above the hole, the mellow soil is piled under the hole, and the picked stones are built on the lower edge of the hole to form a weir with a height of 20-25cm. Dig a small ditch to divert and store rainwater. Masson pine 2 or other suitable tree species are planted in the planting hole. When planting, they should be planted in stages, without nesting or hanging, the root system is stretched, the seedlings are righted, and they are pressed tightly. Masson pine 2 or other suitable tree species form a multifunctional shelterbelt 1 on the top of the slope, which has the functions of maintaining water and soil, conserving water sources, and improving water quality.

3) In the area within 2m of the water level depth, the planting grooves are excavated along the horizontal contour strips. The width of the planting grooves is 20-25cm, the row spacing is 40-60cm, and the depth is 20-30cm. The area between the sinking depth of 2-10m adopts the method of pit-like and fish-scale pit preparation to excavate the planting holes. The planting holes are "V" shaped, the hole spacing is 30-40cm, the hole spacing is 80-100cm, and the hole depth is 20-30cm.

Bermudagrass was planted in the area outside the planting hole by cutting the stem and withdrawing pressure5. The planting method is to cut the stolons and rhizomes of Bermudagrass 5 into small sections of 6-10 cm, sprinkle the mixed soil in the area, and suppress it in time to make it contact with the soil.

Because bermudagrass 5 has strong coverage and is resistant to trampling, the deployment of jute geotextile 6 and planting of vetiver 3 will not have a great impact on its growth.

4) Lay one deck of jute geotextile 6 along the water-response slope of the water-fluctuation zone. The jute geotextile 6 is a kind of biodegradable open mesh fabric woven by low-grade jute raw material and hemp spinning waste, and the specification is: Weight not less than 200g/km ² , warp and weft density: 4-6 per 10cm×10cm. The upper and lower ends of the jute geotextile 6 are fixed in the soil foundation with U-shaped anchors, so that the jute geotextile 6 mesh is tensioned, and the distance between the U-shaped anchors is not more than 2m, and the overlapping length of the adjacent jute geotextile Not less than 15cm, and the superimposed parts are tied in zigzag with degradable and harmless materials.

The present invention adopts jute geotextile 6 for slope protection, and jute geotextile 6 is a new type of material that can quickly control slope erosion. In the field of international water and soil conservation, it is known as "soil rescue" and "lost prevention". . Its advantages in temperature regulation, moisture retention, and beneficial to plant growth are unmatched by geotextiles made of artificial synthetic materials. the reason is:

Jute geotextiles can flexibly cover and attach to the soil surface, effectively reduce raindrop splash erosion, intercept slope water flow, control soil particle movement, and effectively control soil erosion; jute fiber has strong water absorption and natural fiber structure. To a certain extent, it changes the soil pore structure, increases the water absorption capacity of the soil, and its mesh structure can also block rainwater, promote water penetration into the soil, and improve the hydraulic conductivity of the soil, thereby regulating soil temperature and improving soil humidity. The characteristics of the ecological microenvironment provide plants with a better growth environment, thereby promoting plant germination, planting survival, growth and development, increasing the rate of emergence and survival, and significantly promoting the growth of aboveground and underground parts. With the prolongation of the use time, the jute geotextile will gradually degrade and can improve the soil. It has good ecological benefits for slopes that need plants as long-term slope protection measures.

Plus it has a unique mesh structure. The mesh structure allows plants to have enough space to grow, and can fix the seeds to protect the seedlings from wind and rain; each thread that makes up the mesh is like a miniature reservoir, which can absorb and store rainwater and slow down water evaporation during drought .

In short, the use of jute geotextile 6 can slow down the flow rate of slope water, delay the initial runoff time, increase soil seepage, reduce runoff; cover the surface, increase ground coverage, reduce splash erosion, block and reduce water flow, and raise Wet the base level, reduce the flow velocity on the slope, prevent gully erosion, and have high soil conservation benefits.

5) Vetiver 3 is transplanted in the planting grooves in the areas within the water level depth of 2m, and planted in the planting holes in the areas between the water level depths of 2-10m. Plant in clumps in planting grooves and planting holes, and plant 3-4 plants in each clump. Before planting, cut the aboveground part of Vetiver 3 to 25-35cm, and cut the root system to 5-15cm. When planting, lean the plant on one side, keep the angle between the plant and the ground at 60°-45°, and cover with soil from the other side compacted. The cluster distance in the planting tank is 20-30cm.

Vetiver grass 3 is transplanted in the planting tank in the region within 2m of the water leveling depth to form the vetiver grass hedgerow 4 .

Vetiver 3 is an amphibian plant with strong ecological adaptability to stress (drought, wet, cold, heat, acid, alkali), and can resist long-term drought or waterlogging; it has very low requirements on soil, and photosynthetic Strong ability, fast growth, easy planting, easy survival, easy management, and rarely spread diseases and insect pests. Its roots are reticular, and the depth of the root system can reach 2-3m, even 5m. It can hold the soil more firmly, and the root system has a very strong tensile strength, which is 1/6 of the same diameter of mild steel. Stems and leaves can survive long-term flooding. The vetiver hedgerow 4 can improve soil fertility and soil properties, effectively reduce surface runoff and soil erosion, and can trap sediment in the runoff before the hedgerow, and effectively reduce surface runoff.

Vetiver 3 is transplanted in the planting hole in the area between the sinking depth of 2-10m, and the upper and lower vetiver 3 are vertically staggered and planted in the shape of "pin".

In the area between 2-10m depth of water fall, the present invention mixes vetiver and bermudagrass to plant, fully utilizes the characteristics of vetiver 3 developed root system, strong ability of slope protection and soil consolidation, and Bermudagrass 5 stolons and rhizomes to rapidly expand and spread, With the characteristics of strong coverage and trampling resistance, a composite vegetation restoration belt 7 is established, which together with the multi-functional shelterbelt belt 1 and the vetiver hedgerow belt 4 constitute a three-dimensional restoration space to ensure its rooting and restoration on the steep slope of the water-fluctuation zone. Restoring vegetation on a large scale, realizing ecological restoration, effectively controlling soil erosion, and playing a certain role in protecting the reservoir.

6) Water the fixed root water in time after planting.

7) Routine care.

Claims (9)

1. restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir is characterized in that concrete steps are as follows:

1) be chosen in reserve-water-level when minimum, smooth to the falling zone domatic place under repair that meets water, cleaning stone, weeds, rubbish, and carry out suitable hand compaction;

2) fish scale pit land preparation mode excavation kind of plant hole is adopted at outer slope top in falling zone, plants plantation masson pine or other preferents in the plant hole;

3) at the degree of depth 2m that disappears with inner region, employing is excavated planting groove along contours of water table strip soil preparation mode, disappearing employing cave-shaped, fish scale pit land preparation mode excavation kind of a plant hole in zone between the degree of depth 2-10m, cut stem in kind of a plant hole exterior domain employing and remove platen press plantation Bermuda grass;

4) the domatic laying one deck jute geotextiles that meets water along the falling zone, the top and bottom of jute geotextiles all adopt the U-shaped holdfast to be fixed in the soil matrix;

5) in the planting groove of degree of depth 2m that disappear, transplant vetiver in the kind plant hole in the zone that disappears between the degree of depth 2-10m with inner region;

6) in time water normal root water;

7) routine care.

2. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that the kind plant hole at outer slope top, falling zone, the wide 50-80cm in cave, the long 70-100cm in cave, the dark 40-60cm in cave, cave are apart from 200-300cm.

3. according to claim 1 or 2 said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir, when it is characterized in that excavation is planted plant hole, the table mound is placed on the top in cave, mellow soil is deposited in the below in cave, the stone that picks is built into a weir in the lower edge in cave, height of weir 20-25cm, about above the cave two jiaos each tiltedly open and be used to draw the ditch that holds rainwater together.

4. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that jute geotextiles (6) is a kind of biodegradable opening mesh fabric that is made into by yellow kenaf raw material such as low and bast fibre spinning offcuts, specification is: weight is not less than 200g/km ², thread count: every 10cm * 10cm is the 4-6 root.

5. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that the spacing that jute geotextiles (6) upper and lower end is fixed on the U-shaped holdfast in the soil matrix is not more than 2m, the lap of splice of adjacent jute geotextiles is not less than 15cm, and stack place is to wear in a zigzag with the harmless material of degradable ties up.

6. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that transplanting the plantation groove width 20-25cm of vetiver (3), line-spacing 40-60cm is 20-30cm deeply.

7. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, the kind plant hole that it is characterized in that transplanting vetiver (3) is " V " shape, and the cave is apart from 30-40cm, cave line-spacing 80-100cm, the dark 20-30cm in cave.

8. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that plantation vetiver (3) preceding, vetiver overground part sub-cut to 25-35cm, root system cut to 5-15cm, during plantation plant is leaned in a side, plant and ground keep 60 °-45 ° angle, from the compacting of opposite side earthing.

9. according to the said a kind of restoration method for damaged ecosystem in steep-slope area in water-level-fluctuating zone of reservoir of claim 1, it is characterized in that vetiver (3) is planted the 3-4 strain for every clump by the clump plantation in planting groove kind plant hole.

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