CN113565064A

CN113565064A - Riverbank zone structure for urban river ecological restoration and restoration method thereof

Info

Publication number: CN113565064A
Application number: CN202110653696.8A
Authority: CN
Inventors: 孙信柏; 董畔; 夏万成; 王凯; 刘爱宝; 朱辉
Original assignee: Kesheng Environmental Protection Technology Co ltd
Current assignee: Kesheng Environmental Protection Technology Co ltd
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2021-10-29

Abstract

The invention discloses a river bank zone structure for ecological restoration of an urban river and a restoration method thereof, and river channel areas related to the technology comprise a deep water area, a shallow water area, a river flood area, a revetment and a river channel slope of the urban river. The river channel ecological restoration technology takes river channel habitat restoration as a core, is used as a part of a river channel ecological restoration comprehensive system, and is respectively restored from four aspects of reconstruction of a river channel plane and a section structure, control and regulation of river channel hydrology, change of river bottom matrix, introduction of fast-growing organisms, reconstruction of revetments and reconstruction of river channel slopes to form a stable river channel ecological system and a natural landscape. Different from the traditional 'engineering' river channel reconstruction project, the technology mainly aims at improving the functions of river bank zones as the habitat of river channel aquatic, wet and terrestrial animals and plants, recovering the biological diversity of the river channel, and can essentially improve the ecological integrity and sustainability of the river channel and recover the functions of a natural ecological system of the river channel.

Description

Riverbank zone structure for urban river ecological restoration and restoration method thereof

Technical Field

The invention belongs to the technical field of urban river ecological restoration, and particularly relates to a riparian zone structure for urban river ecological restoration and a restoration method thereof.

Background

With the rapid advance of the urbanization process in China and the rapid increase of urban population, a large amount of domestic sewage is generated. Although the construction of domestic sewage treatment plants reduces the load of pollutants borne by urban riverways, many modern urban riverways lose the natural purification capability and the function of an ecosystem of a natural river channel, particularly the function of the natural river channel as a biological habitat, and become a 'dead river' which only plays a role of drainage. But also seriously affect the aesthetic appeal of the river as part of the residential life environment in the city.

At present, the concept of urban river treatment in China is mostly only to recover the drainage and self-purification capacity of the river and improve the effect of the appearance of the river. In the treatment process, an engineering treatment mode is generally adopted, the revetment is pursued to be short, flat and fast in transition, a large amount of building materials such as concrete and mortar rock are used for solidifying the revetment, the ecological niche originally belonging to river channel organisms is occupied, the habitat of a river bank zone is damaged, and serious consequences are caused to the ecological restoration of rivers. This has actually lagged behind the concept of urban river regulation in developed countries. Taking the united states as an example, the united states takes 20 years to treat five large lake regions, and the treatment concept has changed significantly in the process of treating lakes and rivers, from the first time to meet the function of a domestic drinking water source purely for purifying water quality, to the present time to pursue the restoration of lake aquatic ecology and the function as an aquatic animal and plant habitat. The measures adopted by the method comprise the aspects of dismantling a dam which limits the natural flow of the river and the return of fishes, constructing a fish return channel, improving the meandering degree of the river, improving the complexity of the section of the river, recovering aquatic and terrestrial plants of the river and the like. Countries such as canada and new zealand also take various measures to improve the biodiversity and the function of an ecological system of the urban river in the aspect of urban river treatment, for example, an artificial island which is difficult to interfere with human activities is established in a river center and is used as a habitat of birds, amphibians and reptilian organisms. And enlarging the section of the river channel to form a small wetland, so that the biological capacity of the small wetland is improved.

The modern urban river treatment idea not only aims at purifying the water quality of the river, but also improves the aesthetic feeling of the river from sensory aspects such as vision, smell and the like, but also really recovers the function of the urban river as a part of an urban ecological system, so that the river is recovered to be in a natural state as the function of an animal and plant habitat, the biological diversity is improved, and people and nature are harmonious.

Disclosure of Invention

The invention aims to solve the defects in the prior art, and provides a riverside zone structure for urban riverway ecological restoration and a restoration method thereof, which can restore and form a stable riverway ecological system and a stable natural landscape from five aspects of purifying riverway water quality, restoring riverway biological diversity, restoring a riverside zone natural landscape structure and improving revetment and riverway side slope stability. This technique is mainly from promoting the function of riverway aquatic, wetlands and terrestrial animals and plants's habitat, promotes and resumes the angle of river course biodiversity and carries out the transformation in riverway area, can improve river course ecological integrity and sustainability from essence, exerts the function of river course ecosystem self-recovery.

In order to achieve the purpose, the invention adopts the following technical scheme:

designing a riverbank structure for ecological restoration of an urban riverway, which comprises a riverway deep water area, a riverway shallow water area, a river flood area and a riverway side slope, wherein the riverway shallow water area, the river flood area and the river slope are distributed on two sides of the riverway deep water area;

a bank protection belt is arranged between the river flood plain area and the river channel side slope and is used for protecting a stable slope protection structure of the river channel side slope, and the width of the bank protection belt is generally 0.4-1 m; the river channel side slope is a slope section from the edge of an embankment road to a revetment;

the river course is provided with a plurality of river course bending points along the flow direction plane direction, the river course bending points are composed of convex river banks and concave river banks which correspond to each other, the river course bending points recover the natural sinuous property of the river course,

the river channel is provided with a deep pool and a flip dam along the direction of a flow direction section, the deep pool is positioned at the downstream of the flip dam on the same side and distributed along the directions of two sides of the river channel, and the deep pool and a shallow water area of the river channel form a deep pool-shoal sequence structure;

in the aspect of changing the river bottom substrate layer, the river deep water area, the river shallow water area and the river flood area of the river channel utilize the rock blocks, large-particle gravel, natural sand and large wood residues to replace and fill a single river bottom sludge substrate.

Furthermore, the river deep water area is a river area with the average annual water depth of not less than 2m, the river shallow water area is a river area with the average annual water depth of 0.3-2 m, and the river side slope is a river area with the average annual water depth of 0.1m above the average annual water level line and the average annual water depth of less than 0.3 m.

Further, the width of the river channel shallow water area and the river flood area accounts for not less than 40% of the width of the river channel.

Furthermore, the flow-picking dam is of a right-angled triangular reinforced concrete structure, the included angle between the upstream edge of the flow-picking dam and the bank edge of the river channel is 55-70 degrees, the included angle between the downstream edge of the flow-picking dam and the bank edge of the river channel is 20-35 degrees, the bevel edge of the flow-picking dam is parallel to the bank and is positioned at the intersection of the shallow water area and the flood plain area of the river channel, the right-angled vertex of the flow-picking dam extends into 20-40 percent of the shallow water area of the river channel from the cross section direction of the river channel, and the elevation of the top surface of the flow-picking dam is about 0.1-0.3 m higher than the annual average water level of the river

Further, the deep pool is from the distance of flip dam is 2 ~ 3m, is irregular ellipse circular, the major axis of deep pool sets up along river course length direction, and the minor axis of deep pool sets up along river course width direction, the width of deep pool minor axis covers wholly river course shallow water region and 10% ~ 15%'s river course deep water region, the length of deep pool major axis is 40% ~ 60% of whole river course section width.

Furthermore, the bank protection belt is a natural bank protection belt formed by piling up biodegradable woven bags, humus soil capable of planting trees is filled in the woven bags, the depth of the bank protection belt penetrating into a river channel side slope is not less than 1.5m, the width of the bank protection belt is 0.4-1 m, and the top of the bank protection belt is 20-30 cm higher than a river flood plain area adjacent to the bank protection belt. The planted trees are selected from trees with good water resistance, such as Chinese pine, weeping willow, Chinese fir, etc., and the tree age is not less than 3 years. The biodegradable woven bag is required to be completely biodegraded in the future 1-2 years.

The invention also provides a restoration method for the ecology of the urban river, which adopts the riverbank zone structure for the ecological restoration of the urban river, wherein the ecological restoration of the urban river mainly comprises the comprehensive reconstruction of the whole river, the reconstruction of deep water, shallow water and river flood areas of the river, the reconstruction of revetment and the reconstruction of riverway side slopes, the comprehensive reconstruction of the whole river comprises the reconstruction of river planes and section structures, the control and regulation of river hydrology, and the reconstruction of the deep water, shallow water and river flood areas of the river comprises the modification of river bottom matrix and the introduction of fast-growing organisms, and the method specifically comprises the following steps:

step one, controlling and adjusting river hydrology, namely constructing a reservoir at the upstream of a river through engineering measures, arranging a rainwater discharge port and a treated domestic sewage discharge port, excavating or adjusting runoff by utilizing a natural flood discharge lake, controlling the maximum value and the minimum value of river runoff to be not more than 50% of annual average runoff, controlling the average value of river water flow speed below 1m of the water surface at the center of the river to be 0.2-0.5 m/s, maintaining river runoff quantity and flow speed which have certain flux and are relatively stable and relatively stable river water depth to have important significance for keeping the stability of a river ecological system, and mainly embodying the following three aspects:

1. the method maintains the relative stability of the hydrology, the water temperature, the DO and the water quality of the riverway, and is very important for the growth and the propagation of aquatic animals and plants such as fish, aquatic weeds and the like;

2. the soil humidity of the flood plain area is maintained, and a stable and good growing environment is provided for the hygrophytes growing in the flood plain area;

3. the device provides good inhabitation and spawning environments for fishes, benthonic invertebrates and amphibians, and particularly provides a high-quality hatching environment for hatching fertilized eggs, stable water flow with a certain flow rate, stable water temperature and high DO.

Secondly, reconstructing a river channel plane structure, constructing a convex edge river bank of the river channel bending points in a filling mode through engineering measures, constructing a concave edge river bank of the river channel bending points in an excavating mode, and constructing a plurality of river channel bending points along the river channel direction;

thirdly, reforming a river channel section structure, lifting the ratio of a shallow water area and a flood plain area of the river channel to 45% -50% of the full width of the river channel by measures such as mechanical excavation and hydraulic impact, constructing a deep pool by adopting a mechanical excavation mode, and constructing a flow deflecting dam at the upstream of the same side of the deep pool; the reconstruction of the river channel section structure comprises the steps of improving the proportion of shallow water and a river flood area in the width of the whole river channel, and restoring a deep pool-shallow sequence structure of a natural river channel through engineering measures, wherein researches show that in the natural river, more than 70% of river biomass is gathered in the shallow water area and the river flood area. The shallow water area is the main activity place of river organisms and is an important place for the activities, foraging and spawning of fishes, amphibians and benthic invertebrates. The river flood plain area is used as a transition area of river water bodies and river banks and plays an important role in the aspect of exchange of water bodies and land substances and energy. A large amount of organic matters such as plant debris and soil carried by surface runoff slowly enter the water body through the flood plain area, and great contribution is made to the stability of the river channel water body environment. Thus, increasing the proportion of shallow water and river flood areas in a river section has an important role in the overall restoration of river habitat and ecosystem. The effect of the drift dam is to promote the riverbed to be dredged within a certain range by adjusting or limiting the water flow power axis and maintain the structure of the artificial deep pool.

Step four, reforming the river bottom matrix, and filling the single river bottom sludge matrix by using the rock blocks, the large-particle gravel stones, the natural sand and the large wood residues;

introducing fast-growing organisms, introducing the fast-growing organisms and constructing a sustainable and stable development ecosystem;

and step six, revetment reconstruction of the river channel, constructing in a mode that humus soil is filled in a biodegradable woven bag in a connection area of a flood plain area and a river channel side slope, and planting trees in the revetment belt to form a natural type. The conventional revetment mainly aims at stabilizing revetments, uses a large amount of engineering materials such as grouted block stones, reinforced concrete and the like, almost completely cuts off the exchange of substances and energy of river banks and river channel aquatic environments, and is not beneficial to the construction of river channel living habitats. The natural bank protection formed by filling humus with the biological woven bags and planting trees in the humus can ensure efficient substance and energy exchange between water and land, and has the functions of transferring nutrient substances, filtering rainwater, conveying wood chips and organic matters into rivers, providing shade, stabilizing river banks and the like. The biological woven bags only provide side slope protection for 1-2 times before the revetment, and the tree root system finally takes over the role of natural revetment along with the biodegradation of the biological woven bags, the extension of the tree root system and the disc root dislocation.

And step seven, reforming the river channel side slope, planting herbs and low shrubs on the river channel side slope in a side slope full-coverage mode, and mainly aiming at reducing the influence of rain erosion on the river channel side slope and avoiding the influence of heavy rain impact to cause a large amount of silt to enter the river channel and cause adverse influence on the stability of a river channel ecological system. Meanwhile, green plants planted on the side slope of the river channel beautify the side slope environment, and the green plants, aquatic plants and hydrophytes of the river channel together form a multi-level river channel landscape.

And step eight, carrying out ecological restoration protection on the urban river, wherein in the first three years after the completion of the ecological restoration of the urban river, facilities such as an ornamental footpath and an underwater ornamental platform are not required to be built on the river bank and above the river, so as to ensure that the interference of human activities on the restoration of the river habitat is reduced to the minimum. Facilities such as the ornamental footpath and the ornamental platform constructed in the later stage adopt a wood structure as much as possible, and the horizontal distance from the construction range to the revetment is not less than 1.5 m. Many river ecological restoration cases in China pay attention to the landscape ornamental property of the river, so that facilities for citizens to move and enjoy, such as an ornamental footpath and an underwater ornamental platform, are built while the ecological restoration and the reconstruction of the river are carried out, and the river restoration project is opened to the outside early. But the river habitat at the early stage of restoration is certainly very fragile, and the construction activities of building ornamental facilities along the river, the built ornamental facilities themselves and the visitors may cause serious damage to the biological habitat at the early stage of ecological restoration of the river, so that it is necessary to delay the construction of the ornamental facilities along the river and the approach of human activities.

Further, in the second step, the bending rate of the river channel bending point is 1.5-2.5, and the bending point of the river channel is not less than 3 points per 1km, and certainly, the setting of the river channel bending point should be coordinated with urban planning and construction, and for the river channel which is not convenient for setting the bending point, the reconstruction of the river channel section structure can be emphasized. The winding river flow plane shape is the expression of the river natural state, and the function of the winding river flow plane shape is not only to improve the aesthetic feeling of the river natural state. The serpentine river plane configuration creates a river cross section with fluctuating width and a river deep pool-shoal structure along the river. At the bending point of the river channel, the impact of the river bank on one side of the folding point convex edge is enhanced due to the forcible change of the river flow direction, so that the cross section of the river channel can be widened, and a deep pool area at the lower part of the river channel is formed. And a shoal area corresponding to the deep pool is formed on the side of the riverway far away from the bending point of the riverway and the concave side of the bending point. The widened river section reduces the river water flow speed, and becomes an area suitable for the dwelling and inhabitation of aquatic organisms such as fish and the like. The deep pool area formed by the meandering river becomes a common habitat for aquatic organisms such as fish and the like due to factors such as small water flow velocity, low illumination intensity, stable water temperature and the like. In summary, the increase of the meandering of the river not only improves the aesthetic feeling of the river in the natural state, but also provides a large-area comfortable habitat for aquatic organisms such as fish and the like, and promotes the growth and the multiplication of the aquatic organisms.

Further, in the fourth step, the replacement depth of the river bottom matrix layer is 0.5-1 m, and the usage amount ratio of the rock block, the large-particle gravel, the natural sand and the large wood residue is generally 5-6: 5-6: 2: 1, the lump stones and the large wood residues are uniformly distributed, large-particle gravel stones and natural sand are uniformly distributed among gaps and on the surface of the lump stones, in order to prevent the wood residues from floating or flowing downstream along with river water, the large wood residues can be partially pressed on the lower portions of the lump stones and fixed with the lump stones by using a geotechnical net, the average mass of the single lump stones is generally 25-40 kg, the particle size range of the large-particle gravel stones is 10-100 mm, the large-particle gravel stones are distributed in a grading manner, the average particle size of the natural sand is 20-30 meshes, and the large wood residues are round wood residues with the length of not less than 1m and the diameter of not less than 150 mm. Research shows that the biodiversity of rivers can be greatly increased by improving the complexity of the physical form of the river bottom. The flat river bottom base bed of the single sludge matrix is replaced by a complex river bottom base bed which is formed by filling stones, large-particle gravel, natural sand and large wood residues, has uneven structure and is full of holes, the complexity of the physical form of the river bed is greatly improved, and the complex river bottom base bed and aquatic plants in a river channel together provide good habitat and shelter for fish, insects and benthic invertebrates in the river channel, particularly provide good shelter places for hatched aquatic organisms such as fries, shrimp fries and tadpoles in juvenile periods to shelter natural enemies and adult aquatic organisms, and improve the propagation rate of the aquatic organisms.

Further, the method can be used for preparing a novel materialIn the fifth step, the introduction of fast-growing organisms includes aquatic plants, phytoplankton, benthic invertebrates, fish, amphibians and the like. For deep water areas of a river channel, the introduced aquatic plants are submerged plants such as waterweeds, sowthistle herbs, watermifoil and the like, the plants in each area are planted in equal proportion, and the planting density is 10-15 plants/m². For the shallow water area of the river channel, the introduced aquatic plants are submerged plants which are consistent with the deep water area and emergent plants, such as lotus, cattail, reed, arrowhead and the like, and floating plants such as water lily and water lily, and the planting density is 15-20 plants/m². For the river flood plain area of the river channel, the method mainly comprises planting hygrophytes such as yellow flag, copper cash grass, cress and the like, and the planting density is 10-15 plants/m². The phytoplankton can be selected from floating algae such as diatom, chlorella, blue algae and the like and zooplankton such as rotifer, daphnia, and shrimps, and the adding amount is 5-8 kg/km of wet river channel and 40-50 kg/km of wet river channel respectively. The benthic invertebrate can be river snail, freshwater mussel, leech, crayfish, shrimp and the like, and the dosage is 40-50 kg/km of river channel. The fish can be selected from small native fishes such as green , crucian, bitterling, pseudorasbora parva and white fish and large fishes such as silver carp and bighead carp which all eat aquatic plankton and plants, and the adding amount is 40-50 kg/1km river channel wet weight. The amphibian can be selected from frogs and toads, and the dosage of the amphibian is 5-10 kg/km of wet river channel. The introduced fast-growing organisms have the characteristics of strong environmental adaptability and strong reproductive capacity, but the introduced fast-growing organisms cannot cause adverse effects on local organisms and the environment. The introduced fast-growing organisms are native species, preferably native species, and must not introduce foreign species to prevent invasion by foreign species. The introduced fast-growing organisms are complete in variety, reasonably distributed in the three-dimensional space of the river channel, cover all ecological niches of the river channel and form an ecological system with a self-sufficient food net and a complete system. The core of the river ecological restoration technology provided by the invention is the introduction of fast-growing organisms and the construction of a continuously and stably developed ecological system. The reconstruction of the river channel plane and section structure, the control and regulation of river channel hydrology and the change of river bottom matrix are allThe fast-growing organisms introduced into the river channel provide a stable and good living environment, promote the fast growth and propagation of the fast-growing organisms and restore the biological diversity and the ecosystem function of the river channel. The introduction of fast-growing organisms and the construction of a continuously and stably developed ecological system are important for purifying the water quality of the river channel. Algae and aquatic plants can absorb and utilize eutrophic substances in the river water body, and aquatic animals generally eat the algae and the aquatic plants to construct a complete food chain, so that eutrophic salts and organic matters in the river can be quickly consumed, the river water body eutrophication and the accumulation and decay of the organic matters at the river bottom are prevented, and the river water body is purified. The benthonic invertebrates such as river snails and mussels can also secrete natural substances with flocculation effect, capture fine particles in the water body and improve the transparency of the water body of the river channel. Blue or green , rhodeus, small-size fishes such as corncob fish can also use the mosquito larva in the water as food, greatly reduced the quantity of river coastal mosquito, improve resident's living environment, reduce the emergence probability of mosquito infectious disease. From the aspect of river landscape construction, the stable ecological system created by introduction of fast-growing organisms improves the transparency of the river water body, avoids bad smell generated by bottom mud decay, and improves the overall impression of the river. Various types of aquatic and hygrophytes from the deep water area of the river channel to the flood beach build natural aesthetic feeling of different levels, and have higher ornamental value.

The invention provides a riparian zone structure for urban river ecological restoration and a restoration method thereof, which have the beneficial effects that:

(1) the method is different from the traditional 'engineering' river channel reconstruction technology, and mainly aims at improving the function of a riparian zone as a habitat of river channel aquatic, wet and terrestrial animals and plants, recovering the diversity of river channel organisms, essentially improving the ecological integrity and sustainability of the river channel and recovering the function of a natural ecological system of the river channel.

(2) The invention relates to comprehensive transformation of river channel planes, sections, deep water, shallow water, river flood beaches, revetments and river channel slopes, and constructs river channel biological habitats in the whole-length and full-section areas of the river channel.

(3) The invention adopts various river channel modification means, provides a stable and good living environment for fast-growing organisms introduced into the river channel, promotes the fast growth and propagation of the organisms, and recovers the biological diversity and the ecological system function of the river channel. The method comprises the following steps: firstly, reforming a flat section structure of a river channel (increasing the serpentine property of the river channel and constructing a deep pool-shallow talk sequence structure); secondly, controlling and adjusting river hydrology, and keeping the flow, the flow speed and the water depth of the river relatively stable; thirdly, the modification of the river bottom matrix improves the complexity of the physical form of the river; fourthly, the bank protection belt adopts a natural bank protection belt which can be used for filling humus soil in biodegradable woven bags and planting trees; and fourthly, vegetation protection of the river channel side slope.

(4) The core of the river ecological restoration technology provided by the invention is the introduction of the fast-growing organisms and the construction of a sustainable and stable development ecosystem. The fast-growing organisms can effectively purify water quality, improve the transparency of river water, kill mosquitoes, suppress bad smell and build natural aesthetic feeling of different levels of a river channel.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic perspective view of the river channel of the present invention;

FIG. 2 is a schematic view of the river channel plane structure of the present invention;

FIG. 3 is a schematic view of the cross-sectional structure of the river channel of the present invention;

labeled as: 1. the river course deep water area 2, the river course shallow water area 3, the river course side slope 4, the bank protection band 5, the river course bending point 51, the convex edge bank 52, the concave edge bank 6, the drift dam 7, the deep pool 8, the river flood area 9, the river bottom matrix layer 10 and the reservoir.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. These examples are intended to illustrate the invention only and are not intended to limit the scope of the invention. In the description of the present invention, it is to be noted that the terms "provided with" and "connected" are to be interpreted broadly, unless explicitly stated or limited otherwise. The specific meanings of the above terms in the present invention can be understood in specific cases by those of ordinary skill in the art.

The structural features of the present invention will now be described in detail with reference to the accompanying drawings.

Example 1

Referring to fig. 1-3, the invention provides a method for restoring ecology of urban riverways, which is implemented in 2019 for 10 months, and aims to restore the ecology of riverways at a river reach in Jiangning district of Nanjing city, wherein the length of a section is about 6km, the width of the riverway is 20-25 m, and the deepest part of the riverway is about 4.5-6 m. The whole river channel is mainly subjected to rainwater and domestic sewage of residents in river-along urban areas. The ecological restoration of the urban river mainly comprises the comprehensive reconstruction of the whole river, the reconstruction of deep water, shallow water and flood plain areas of the river, the reconstruction of a bank protection zone and the reconstruction of a side slope of the river. The overall comprehensive reconstruction of the river channel comprises the reconstruction of a river channel plane and section structure and the control and adjustment of river channel hydrology. The transformation of river channel deep water, shallow water and river flood area includes the change of river bottom matrix and the introduction of fast-growing organisms.

River channel planar reformation focuses mainly on restoring the natural serpentine nature of the river channel through engineering measures. The bending points of the original river channel on the length of 6km are 4, and the bending rates of the bending points 5 of the river channel are 1.7, 2.4, 2.0 and 1.9 respectively. However, the number of the bending points 5 of the river channel cannot be increased due to urban planning and construction, so the engineering focuses on the reconstruction of the river channel section structure. In the aspect of reconstruction of a river channel section structure, the occupation ratio of shallow water and a river flood area is increased to 45% -50% of the full width of the river channel by measures such as mechanical excavation and hydraulic impact. On the other hand, the deep pool-shoal sequence structure of the natural river channel is recovered through engineering measures, and the recommended engineering measures are mechanical deep pool excavation and setting of a flip dam 6. The excavation deep pool 7 is located in the downstream of the same side of the flow-deflecting dam 6, the distance from the flow-deflecting dam 6 to the excavation deep pool is about 3m, the excavation deep pool is in an irregular oval shape, the long axis of the excavation deep pool should be along the length direction of the river channel, and the short axis of the excavation deep pool should be along the width direction of the river channel. When viewed from the cross section of the river channel, the river channel covers the whole shallow water area and 15% of the deep water area, and the length of the long axis of the river channel is generally 55% of the width of the cross section of the river channel. The slip dam 6 is of a reinforced concrete structure, the planar shape of the slip dam is a right-angled triangle, the included angle between the upstream side and the bank side of the river channel is 60 degrees, and the included angle between the downstream side and the bank side of the river channel is 30 degrees. The bevel edge is parallel to the river bank and is positioned at the intersection of the river channel shallow water area 2 and the river flood area 8. From the cross section of the river channel, the right-angle vertex extends to 25% of the deep water area 1 of the river channel. The elevation of the top surface of the flow-selecting dam 6 is about 0.2m higher than the annual average water level of the river.

By investigating local hydrologic data, the net river flow varies greatly over the year, with the maximum runoff over 60% of the average annual runoff. Overlarge runoff in rainy season causes the water body of the river to be turbid, and a large amount of floating objects are carried. In the engineering implementation, two methods for adjusting the river runoff are adopted, one is to control the gate flow at the upstream of the river, and the other is to get through the connection with the small lake along the river. After water conservancy adjustment, the maximum runoff in rainy season is reduced to not more than 50% of the average annual runoff. The average flow rates of the rivers in the dry period and the rich period were 0.21m/s and 0.44m/s, respectively. The deepest part of the river is more than 4.5m, and the requirements are met.

In the aspect of changing the river bottom matrix layer 9, the single river bottom sludge matrix is filled with the lump stones, the large-particle gravel stones, the natural sand and the large wood residues, and the filling depth is 1 m. The using amount ratio of the rock block, the large-particle gravel stone, the natural sand and the large wood residue is generally 5: 5: 2: 1. the shape and size of the block stone are not required, but the strength is required to meet the use requirement, and the average mass of the single block stone is 30 kg. The particle size range of the large-particle gravel is 10-100 mm, and the large-particle gravel is in graded distribution. The average particle size of the natural sand is 30 meshes. Large wood residues are generally round wood residues with a length of more than 1.5m and a diameter of more than 200 mm. The effect that has after changing and filling the completion is that stone and large-scale wooden residuum evenly distributed, large granule gravel and natural sand evenly distributed are in the gap of stone and surface. The wooden residual body part is pressed on the lower part of the block stone and is firmly tied with the block stone by using a geonet.

The introduction of fast-growing organisms includes aquatic plants, phytoplankton and other animalsThe species invertebrates, fish and amphibians. For deep water areas of a river channel, the introduced aquatic plants are submerged plants comprising three aquatic plants of waterweed, common sowthistle herb and watermifoil, the plants in each area are planted in equal proportion, and the planting density is 10 plants/m². For a shallow water area of a river channel, the introduced aquatic plants are submerged plants (consistent with the deep water area), emergent aquatic plants are planted with cattail, reed and iris fallax, floating plants are planted with water lily, water lily and nuphar pumilum, the three plants are planted in equal proportion, the planting density is 15 plants/m². Three hygrophytes of yellow flag, copper coin grass and cress are planted in the river overflowing beach area of the river channel, and the planting density is 10 plants/m². The floating swimming plants are selected from three mixed algae of diatom, chlorella and blue algae and three zooplankton of rotifer, daphnia and shrimps, and the adding amount is 5kg/km of wet weight of the river channel and 40kg/km of wet weight of the river channel respectively. The benthic invertebrate is selected from four animals including river snail, freshwater mussel, leech and crayfish, and the dosage of the benthic invertebrate is 40kg/km river channel. The fish is selected from green , crucian, bitterling and silver carp bighead carp, and the adding amount is 50kg of wet weight per 1km river channel. The amphibian selects frog and toad, and the dosage is 10kg/km of wet weight in river channel.

The bank protection belt 4 of the river adopts a biodegradable woven bag filled with humus, and a bank protection formed by willow and metasequoia is planted in the humus. The depth of the revetment penetrating into the river channel side slope is about 2m, and the width is 0.8 m. The top of the soil revetment is about 30cm higher than the river flood beach area adjacent to the soil revetment. The biodegradable woven bag is required to be completely biodegraded in the future 1-2 years.

The engineering project also builds a net-shaped isolation zone between the river channel and the road to ensure that human activities do not enter the river channel area in the next three years.

Example 2

Referring to fig. 1 to 3, the invention provides a method for restoring ecology of an urban river, which specifically comprises the following steps: the engineering case is implemented in 5 months in 2020, aims at river channel ecological restoration in Yao sea areas of Hefei city, and has the section length of about 15km, the river channel width of 30-35 m and the deepest depth of about 3.5-5.5 m. The whole river channel is mainly used for receiving rainwater and domestic sewage of residents in river-along urban areas. The ecological restoration of the urban river mainly comprises the comprehensive reconstruction of the whole river, the reconstruction of deep water and shallow water of the river and flood plain areas, the reconstruction of revetment and the reconstruction of river side slopes. The overall comprehensive reconstruction of the river channel comprises the reconstruction of a river channel plane and section structure and the control and adjustment of river channel hydrology. The transformation of river channel deep water, shallow water and river flood area includes the change of river bottom matrix and the introduction of fast-growing organisms.

River channel planar reformation focuses mainly on restoring the natural serpentine nature of the river channel through engineering measures. The bending points 5 of the original river channel on the length of 15km are 7 in total, and the bending rates of the bending points 5 of the river channel are 1.2, 1.6, 1.3, 1.1, 2.0, 2.2 and 1.9 respectively. In engineering practice, the bending rate of the river channel is improved by filling the concave river bank 52 of the river channel bending point and excavating the convex river bank 51 of the river channel bending point 5. However, the number of the bending points of the river channel cannot be increased due to urban planning and construction, so the engineering focuses on the reconstruction of the river channel section structure. In the aspect of reconstruction of the river channel section structure, the occupation ratio of a river channel shallow water area 2 and a river flood area 3 is increased to 45% -50% of the whole width of the river channel through measures such as mechanical excavation and hydraulic impact. On the other hand, the deep pool-shoal sequence structure of the natural river channel is recovered through engineering measures, and the recommended engineering measures are mechanical deep pool excavation and setting of a flow-picking dam 6. The excavation deep pool 7 is located at the same side downstream of the flip dam 6, the distance from the flip dam 6 is about 3m, the excavation deep pool is irregular and elliptical, the long axis of the excavation deep pool should be along the length direction of the river channel, and the short axis of the excavation deep pool should be along the width direction of the river channel. The length of the long axis of the river channel cross section covers the whole river channel shallow water area 2 and 15% of the river channel deep water area 1, and the length of the long axis is generally 55% of the width of the whole river channel cross section. The slip dam 6 is of a reinforced concrete structure, the planar shape of the slip dam is a right-angled triangle, the included angle between the upstream side and the bank side of the river channel is 60 degrees, and the included angle between the downstream side and the bank side of the river channel is 30 degrees. The hypotenuse is parallel to the bank and is located at the intersection of the shallow water area and the flood plain area. From the cross section of the river channel, the right-angle vertex extends to 30% of the deep water area 1 of the river channel. The top surface of the slip dam 6 is about 0.3m higher than the annual average water level of the river.

By investigating local hydrologic data, the net river discharge varies greatly over the course of a year, with minimum annual discharge of less than 50% of the average annual discharge. In the dry period, due to the fact that runoff is too small, more than 70% of cross sections of riverbeds of the riverways are in a dry state, most areas of shallow water and all river flood areas 8 become complete land, and survival of a riverway ecological system is seriously affected. In the engineering implementation, two methods for adjusting the river channel runoff are adopted, one is to increase the gate opening flow at the upstream of the river, and the other is to add rainwater and treated sewage drainage openings at two banks of the river channel. After adjustment, the minimum runoff in rainy season drops to 65% of the annual average runoff. The average flow rates of the rivers in the dry period and the rich period are 0.35m/s and 0.5m/s, respectively. The deepest part of the river is more than 4m, and the requirements are met.

The introduction of fast-growing organisms includes aquatic plants, phytoplankton, benthic invertebrates, fish, amphibians and the like. For deep water areas of a river channel, the introduced aquatic plants are submerged plants comprising three aquatic plants of waterweed, common sowthistle herb and watermifoil, the plants in each area are planted in equal proportion, and the planting density is 10 plants/m². For the river channel shallow water area 2, the introduced aquatic plants are submerged plants(consistent with a deep water area), planting Typha angustifolia, Phragmites communis and Iris floribunda in emergent aquatic plants, planting water lily, herba Solidaginis and Spirodela polyrhiza in floating aquatic plants, planting the three plants in equal proportion, and planting density of 15 plants/m². For river overflow beach area 8 of river channel, three hygrophytes of yellow flag, copper coin grass and cress are planted, and the planting density is 10 plants/m². The floating swimming plants are selected from three mixed algae of diatom, chlorella and blue algae and three zooplankton of rotifer, daphnia and shrimps, and the adding amount is 5kg/km of wet weight of the river channel and 40kg/km of wet weight of the river channel respectively. The benthic non-vertebral animal is selected from four animals of river snail, freshwater mussel, leech and crayfish, and the dosage is 40kg/km river channel. The fish is selected from green , crucian, bitterling and silver carp bighead carp, and the adding amount is 50kg of wet weight per 1km river channel. The amphibian selects frog and toad, and the dosage is 10kg/km of riverway with wet weight.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A riverbank structure for ecological restoration of an urban riverway is characterized by comprising a riverway deep water area (1), and a riverway shallow water area (2), a riverway flood area (8) and a riverway side slope (3) which are distributed at two sides of the riverway deep water area (1);

a bank protection belt (4) for protecting the stability of the river channel side slope is arranged between the river floodbeach area (8) and the river channel side slope (3);

a plurality of river channel bending points (5) are arranged on the river channel along the flow direction plane direction, and the river channel bending points (5) are composed of convex river banks (51) and concave river banks (52) which correspond to each other;

the river channel is provided with a deep pool (7) and a flip dam (6) along the flow direction cross section direction, the deep pool (7) is positioned at the same side downstream of the flip dam (6) and distributed along the directions of two sides of the river channel, and the deep pool (7) and the river channel shallow water area (2) form a deep pool-shallow beach sequence structure;

in the aspect of changing the river bottom matrix layer (9), the river channel deep water area (1), the river channel shallow water area (2) and the river flood area (8) are filled with single river bottom sludge matrix by using lump stones, large-particle gravel stones, natural sand and large wood residues.

2. The riverbank structure for the ecological restoration of the urban riverway according to claim 1, wherein the riverway deep water area (1) is a riverway area with the annual average water depth of not less than 2m, the riverway shallow water area (2) is a riverway area with the annual average water depth of 0.3-2 m, and the riverway side slope (3) is a riverway area with the annual average water depth of 0.1m above and the annual average water depth of less than 0.3 m.

3. The riparian zone construction for the ecological restoration of urban river course according to claim 1, characterized in that the width of river course shallow water area (2) and river flood area (8) is not less than 40% of the width of river course.

4. The riparian zone structure for the ecological restoration of the urban river channel according to claim 1, wherein the slip dam (6) is a reinforced concrete structure with a right-angled triangle shape, the included angle between the upstream side of the slip dam (6) and the river channel shore is 55-70 degrees, the included angle between the downstream side of the slip dam (6) and the river channel shore is 20-35 degrees, the hypotenuse of the slip dam (6) is parallel to the river channel and is located at the intersection of the river channel shallow water area (2) and the river flood area (8), the right-angled vertex of the slip dam (6) extends to 20-40 percent of the river channel shallow water area (2), and the top surface level of the slip dam is about 0.1-0.3 m higher than the annual average water level of the river.

5. The riverbank structure for urban riverway ecological restoration according to claim 1, wherein the distance between the deep pool (7) and the flip dam (6) is 2-3 m, the deep pool is in an irregular ellipse shape, the long axis of the deep pool (7) is arranged along the length direction of the riverway, the short axis of the deep pool (7) is arranged along the width direction of the riverway, the width of the short axis of the deep pool (7) covers the whole riverway shallow water area (2) and 10% -15% of riverway deep water area (1), and the length of the long axis of the deep pool (7) is 40% -60% of the width of the whole riverway section.

6. The riverbank structure for ecological restoration of urban riverways according to claim 1, wherein the revetment belt (4) is a natural revetment formed by stacking biodegradable woven bags filled with humus capable of planting trees, the depth of the revetment belt (4) penetrating into a riverway side slope (3) is not less than 1.5m, the width of the revetment belt is 0.4-1 m, and the top of the revetment belt (4) is 20-30 cm higher than a riverbank overflowing beach area (8) adjacent to the revetment belt.

7. A restoration method for urban river ecology adopts the riverbank zone structure for urban river ecology restoration as claimed in any one of claims 1 to 6, and is characterized in that the comprehensive reconstruction of the whole river relates to the reconstruction of river planes and section structures, the control and regulation of river hydrology, the reconstruction of river bottom matrix, the introduction of fast-growing organisms, the reconstruction of river bank protection and the reconstruction of river slopes, and specifically comprises the following steps:

step one, controlling and adjusting river hydrology, namely building a reservoir at the upstream of a river through engineering measures, arranging a rainwater discharge port and a treated domestic sewage discharge port, excavating or adjusting runoff by utilizing a natural flood discharging lake, controlling the maximum value and the minimum value of river runoff not to exceed 50% of annual average runoff, and controlling the average value of river current speed below 1m of the water surface at the center of the river to be 0.2-0.5 m/s;

secondly, reconstructing a river channel plane structure, constructing a convex bank (51) of the river channel bending points (5) in a filling mode through engineering measures, constructing a concave bank (52) of the river channel bending points (5) in an excavating mode, and constructing a plurality of river channel bending points (5) along a river channel direction;

thirdly, reforming a river channel section structure, lifting the ratio of a river channel shallow water area (2) to a river flood area (8) to 45% -50% of the full width of the river channel through measures such as mechanical excavation and hydraulic impact, constructing a deep pool (7) in a mechanical excavation mode, and constructing a flow deflecting dam (6) at the upstream of the same side of the deep pool (7);

step six, reforming a revetment belt (4) of the river channel, constructing the connection area of the flood plain area (8) and the river channel side slope (3) in a mode of filling humus soil in a biodegradable woven bag, and planting trees in the revetment belt (4) to form a natural type;

step seven, reforming the river channel side slope, planting herbs and low shrubs on the river channel side slope (3) in a side slope full-coverage mode;

and step eight, carrying out ecological restoration protection on the urban river channel, wherein in the first three years after the ecological restoration of the urban river channel is finished, facilities such as an ornamental footpath and an underwater ornamental platform are not required to be built on the river bank and the river channel, the facilities such as the ornamental footpath and the ornamental platform built in the later period adopt a wood structure as much as possible, and the horizontal distance between the building range and the revetment is not less than 1.5 m.

8. The restoration method for the ecological restoration of the urban river according to claim 7, wherein in the second step, the curvature of the river curve point (5) is 1.5-2.5, and the number of the river curve points is not less than 3 per 1 km.

9. The method for restoring the ecology of urban riverways according to claim 7, wherein in the fourth step, the depth of the river bottom matrix layer (9) is 0.5-1 m, and the ratio of the used amount of the rock block, the large-particle gravel, the natural sand and the large wood residue is generally 5-6: 5-6: 2: the method comprises the following steps of 1, uniformly distributing block stones and large wood residues, uniformly distributing large-particle pebble stones and natural sand among gaps and on the surfaces of the block stones, partially pressing the large wood residues on the lower portions of the block stones and fixing the large wood residues with a geotechnical net, wherein the average mass of the single block stones is generally 25-40 kg, the particle size range of the large-particle pebble stones is 10-100 mm, the large-particle pebble stones are distributed in a grading manner, the average particle size of the natural sand is 20-30 meshes, and the large wood residues are round wood residues with the length of not less than 1m and the diameter of not less than 150 mm.

10. The method for restoring ecology in urban riverways according to claim 7, wherein in the fifth step, the introduction of fast living creatures comprises aquatic plants, zooplankton, benthic invertebrates, fish and amphibians, submerged plants with a planting density of 10-15 plants/m 2 are introduced into the deep water area (1) of the riverway, submerged plants, emergent plants and floating plants with a planting density of 15-20 plants/m 2 are introduced into the shallow water area (2) of the riverway, the flood plain area (8) is mainly planted with hydrophytes, the zooplankton plants can be selected from floating algae and zooplankton, the feeding amount of the submerged plants is 5-8 kg/km of wet weight and 40-50 kg/km of wet weight of the riverway, the feeding amount of the benthic invertebrates is 40-50 kg/km, the fish can be selected from small native-aquatic fishes and large-sized fishes feeding on the phytoplankton completely, the adding amount of the amphibians is 40-50 kg/km of the river channel, and the adding amount of the amphibians is 5-10 kg/km of the river channel.