Self-adaptive flood-drought mutual aid system and method for riverway in arid region based on terrain remodeling

Abstract

The invention discloses a self-adaptive flood-drought mutual aid system and method for a river channel in an arid region based on terrain remodeling, and belongs to the technical field of ecological water conservancy projects. The system comprises a water and sediment separation topographic unit, a threshold value overflow topographic unit, a narrow and deep evaporation restraining topographic unit and an outer side beach overflowing flood area which are sequentially arranged in the water flow direction and coupled. A bottom plate of the water-sediment separation shape unit is provided with a transverse slope inclining towards an outer side concave bank, and bottom layer sediment is guided by gravity to be conveyed to the outer side; the narrow-deep evaporation-inhibiting terrain unit adopts a narrow-deep compound section with a large depth-to-width ratio to collect clear water so as to inhibit evaporation; and the top of the threshold overflow terrain unit forms a physical threshold for flood and drought switching. The invention further discloses a corresponding implementation method. According to the system, by remodeling the geometric shape of a riverbed, self-adaptive switching between clear water returning, efficient sand discharging and evaporation restraining in the dry season and muddy water beach overflowing, ecological supply and automatic dredging in the flood season is achieved, and the problems of water-sand contradiction and ecological water use of wandering rivers in the arid region are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of ecological water conservancy engineering technology, and in particular to an adaptive flood and drought relief system and method for arid river channels based on topographic reshaping. Background Technology

[0002] Inland rivers in the arid northwest region of my country are characterized by wide and shallow riverbeds, meandering river course, high sediment content, and intense evaporation. Their water resource utilization faces the following major technical bottlenecks: 1. The contradiction between the difficulty of water diversion and the difficulty of sand control: Although existing technologies (such as artificial bend-type water diversion hubs) utilize bend-type circulation for sand removal, their sand removal efficiency heavily depends on the centrifugal force generated by high flow velocity. During the dry season, under low flow velocity conditions, the centrifugal force is drastically reduced, resulting in insufficient sand removal power. Severe siltation easily occurs at the water intake, requiring frequent mechanical dredging.

[0003] 2. Severe water resource wastage: Wide and shallow meandering rivers have a large free water surface area. Under the strong sunlight and wind in arid areas, the wastage loss is extremely high, resulting in a large amount of precious ecological base flow being lost during transportation.

[0004] 3. Weak flood and drought regulation capacity: Traditional river management often focuses on single flood control or single water supply, lacking a comprehensive utilization model that can adapt to drastic flow fluctuations and transform floodwater sediment into ecological resources.

[0005] Therefore, there is an urgent need for a new method for river management and utilization that is low-cost, low-maintenance, and adaptable to the unique hydrological conditions of arid regions. Summary of the Invention

[0006] The purpose of this invention is to provide an adaptive flood and drought relief system and method for arid river channels based on terrain reshaping, in order to solve the problems of prominent contradictions in water diversion and sediment discharge, large evaporation losses, and difficulty in coordinating the utilization of flood and drought resources in the existing technologies.

[0007] To achieve the above objectives, this invention provides an adaptive flood and drought mitigation system for arid river channels based on terrain reshaping, comprising four reshaped terrain units arranged in parallel and coupled along the direction of water flow. The four reshaped terrain units include: The water and sediment differentiation topographic unit is configured as a curved channel with a reshaped bottom plate that has a transverse slope that slopes outwards towards the concave bank. This is used to drive the high sediment content water flow at the bottom layer to the outside under the dominance of gravity, so that the surface clear water accumulates on the inner convex bank. The narrow and deep evaporation suppression topographic unit is connected to the inner convex bank diversion path of the water and sediment differentiation topographic unit. It adopts a narrow and deep compound cross-section structure with a depth-to-width ratio of not less than 0.8 and is used to collect and transport the stratified clear water. The outer floodplain is located on the outer concave bank of the aforementioned water-sediment differentiation topographic unit. It has been reshaped into a wide and shallow riverbed, serving as a sediment discharge channel and a flood discharge and ecological replenishment area. The threshold overflow terrain unit is located between the narrow and deep evaporation suppression terrain unit and the outer floodplain, and its top elevation constitutes the physical threshold for the switching between flood and drought.

[0008] Preferably, in the water-sediment differentiation topographic unit, the lateral slope i tilting towards the outer concave bank c The value ranges from 3% to 5%.

[0009] Preferably, it also includes an active capture terrain group located upstream, which includes a discontinuous groynes extending to the edge of the main channel swing zone and a V-shaped water-binding dike connecting the ends of the groynes. The V-shaped water-binding dike is arranged in a funnel shape in the plane.

[0010] Preferably, the V-shaped water-binding diversion dike adopts a variable porosity composite structure, including a dense seepage-proof body on the water-facing side and a permeable energy-dissipating body on the back side, and the dense seepage-proof body and the permeable energy-dissipating body are connected by multiple through-type tie rods.

[0011] Preferably, the bottom elevation of the sand discharge channel on the outer side of the water-sediment differentiation topographic unit is lower than the bottom elevation of the narrow-depth evaporation suppression topographic unit, and a sand-prevention embankment is formed at the connection between the two using the difference in bottom elevation.

[0012] Preferably, the main earthwork of the threshold overflow terrain unit comes from the in-situ earthwork generated by excavating the narrow-depth anti-evaporation terrain unit.

[0013] Preferably, the system is provided with a low potential energy discharge control port at the end. The outlet shape of the low potential energy discharge control port is configured to form a larger longitudinal gradient during the flood season, so as to increase the flow velocity and cooperate with the high water level to realize the self-dredging of the narrow and deep evaporation suppression terrain unit.

[0014] The present invention also provides an adaptive flood and drought relief method for arid river channels based on the above system, comprising the following steps: S1. Active capture: Utilize the active capture terrain group upstream to straighten and converge the wandering river flow to the system inlet; S2. Topographic reshaping and sediment removal: During the dry season, water flows into the water-sediment differentiation topographic unit. Under the gravity provided by the lateral slope, the bottom sediment is forced to slide to the depth of the outer concave bank. S3, Geometric evaporation suppression: During the dry season, clean water is confined within the deep trenches of the narrow and deep evaporation suppression terrain unit to reduce evaporation by reducing the free water surface area; S4. Mutual Assistance and Transformation: When the water level rises above the top height of the threshold overflow terrain unit, the excess water overflows into the outer floodplain, and at the same time, the flow velocity in the narrow and deep anti-evaporation terrain unit increases, realizing the self-dredging of the channel.

[0015] Preferably, in step S2, the lateral slope i c The value is set to 3% to 5% to ensure that, under low flow velocity during the dry season, the lateral gravity sliding component of the bottom sediment particles is greater than their static friction force on the riverbed.

[0016] Preferably, in step S3, the depth-to-width ratio of the narrow-depth anti-evaporation terrain unit is not less than 0.8 and is at least 5 times the typical depth-to-width ratio of a natural river channel.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: The system and method provided by this invention construct an adaptive system coupling three core mechanisms: gravity sediment discharge, geometric evaporation suppression, and threshold scheduling, by reshaping the riverbed geometry. During the dry season, at low flow velocities, this system can efficiently discharge sediment and obtain clean water using the principle of gravity sliding, while significantly suppressing evaporation through narrow and deep cross-sections. During the flood season, it automatically achieves flood discharge and ecological replenishment of turbid water through physical thresholds, and promotes self-dredging of deep channels. This invention achieves systematic and adaptive regulation of water and sediment processes and evaporation losses in wandering rivers in arid regions, solving the technical problems of traditional methods such as sediment discharge failure during the dry season, large evaporation losses, and difficulty in balancing flood and drought conditions. It provides an innovative engineering solution for the efficient utilization of regional water resources and ecological restoration. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0019] Figure 1 This is a schematic diagram of the system planar layout and flow field according to an embodiment of the present invention.

[0020] Figure 2 This is a cross-section and earthwork balance diagram of the narrow-depth evaporation suppression terrain and the threshold overflow terrain in an embodiment of the present invention.

[0021] Figure 3 This is a cross-section of the water-sediment differentiation topographic unit of the present invention and a schematic diagram of the gravity sediment discharge principle.

[0022] Figure 4 This is a cross-sectional view of the variable porosity structure of the V-shaped water-constricting dike of the present invention.

[0023] In the figure: 1. Water and sediment differentiation topographic unit; 2. Threshold overflow topographic unit; 3. Narrow and deep evaporation suppression topographic unit; 4. Outer floodplain flood zone; 5. Low potential energy discharge control outlet; 11. Discontinuous groynes group; 12. V-shaped water-binding dike; 12a. Dense seepage prevention body; 12b. Permeable energy dissipation body. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] like Figures 1 to 4 As shown, this invention provides an adaptive flood and drought mitigation system for arid river channels based on terrain reshaping, comprising four reshaped terrain units arranged in parallel and coupled along the water flow direction. The four reshaped terrain units include: Water and sediment differentiation topographic unit 1 is configured as a curved channel with a reshaped bottom plate that has a transverse slope that slopes outward toward the concave bank. This is used to drive the high sediment content water flow at the bottom layer to the outside under the dominance of gravity, so that the surface clear water accumulates on the convex bank inward. Narrow and deep evaporation suppression topographic unit 3 is connected to the inner convex bank diversion path of water and sediment differentiation topographic unit 1. It adopts a narrow and deep compound cross-section structure with a depth-to-width ratio of not less than 0.8 to collect and transport the stratified clear water. The outer floodplain 4 is located on the outer concave bank of the water-sediment differentiation topographic unit 1. It has been reshaped into a wide and shallow riverbed to serve as a sediment discharge channel and a flood discharge and ecological replenishment area. Threshold overflow terrain unit 2 is located between narrow and deep evaporation suppression terrain unit 3 and outer floodplain 4, and its top elevation constitutes the physical threshold for flood-drought switching.

[0026] This invention achieves a systematic reshaping of river water and sediment processes by setting up a coupled structure of four core units: a water-sediment differentiation topographic unit 1, a narrow-depth evaporation-suppressing topographic unit 3, an outer floodplain floodplain 4, and a threshold overflow topographic unit 2. The water-sediment differentiation topographic unit 1 is responsible for separating water and sediment under gravity; the narrow-depth evaporation-suppressing topographic unit 3 is responsible for transporting clean water and suppressing evaporation; the outer floodplain floodplain 4 is responsible for discharging sediment and preventing flood overflow; and the threshold overflow topographic unit 2 acts as a physical switch to adaptively switch between flood and drought conditions. This integrated design fundamentally changes the traditional single-function mode of river management, forming an adaptive system capable of simultaneously addressing multiple objectives such as sediment diversion, evaporation suppression, flood discharge, and ecological water replenishment.

[0027] Further optimization of the scheme: In water-sediment differentiation topographic unit 1, the lateral slope i tilting towards the outer concave bank... c The value ranges from 3% to 5%.

[0028] By changing the lateral slope i c Setting the sediment discharge rate within a specific range of 3% to 5% ensures that, under critical conditions such as low river flow velocity and significantly reduced centrifugal force in traditional bend circulation during the dry season, the downslope gravity sliding component acting on the bottom sediment particles can overcome the static friction of the riverbed. This design makes the sediment discharge process not entirely dependent on the water flow velocity, thus solving the core defect of insufficient sediment discharge power in existing technologies during the dry season and achieving efficient and stable sediment discharge under all operating conditions, especially during the dry season.

[0029] Further optimization of the scheme also includes an active topographic capture group located upstream. The active topographic capture group includes a discontinuous groynes group 11 extending to the edge of the main channel swing zone and a V-shaped water-binding dike 12 connecting the end of the groynes group. The V-shaped water-binding dike 12 is arranged in a funnel shape in the plane.

[0030] By setting up an active topographic capture group consisting of discontinuous groynes 11 and V-shaped water-binding dikes 12 upstream, the problem of unstable main channel position in wandering rivers can be effectively addressed. The discontinuous groynes 11 can initially straighten the river course and promote siltation and beach formation, while the V-shaped water-binding dikes 12, arranged in an "eight"-shaped funnel pattern, can further smooth and stably guide the initially straightened water flow to the system's inlet area, ensuring that the system can effectively capture and process water flow under various inflow conditions, thereby improving the reliability and stability of the entire system operation.

[0031] The V-shaped water-binding diversion dike 12 adopts a variable porosity composite structure, including a dense seepage-proof body 12a on the water-facing side and a permeable energy-dissipating body 12b on the back side, and the dense seepage-proof body 12a and the permeable energy-dissipating body 12b are connected by multiple through-type tie rods.

[0032] The V-shaped water-binding dike 12, constructed using a variable porosity composite structure, integrates multiple functions. The dense impermeable body 12a on the upstream side (composed of closely spaced piles and water-blocking geotextile bags) effectively prevents water from seeping into the dike's interior, avoiding structural damage such as piping and scouring caused by seepage pressure. The permeable energy-dissipating body 12b on the downstream side (composed of stacked gabions) possesses good permeability and flexibility, capable of absorbing water flow impact energy and adapting to potential riverbed deformation. The two are connected by a through-type tie rod, ensuring the structural integrity and stability. This design enables the V-shaped water-binding dike 12 to simultaneously possess comprehensive capabilities for diversion, seepage prevention, energy dissipation, and deformation adaptation in strongly scoured, meandering river environments.

[0033] The scheme was further optimized so that the bottom elevation of the sediment discharge channel on the outer side of the water and sediment differentiation topographic unit 1 was lower than that of the bottom elevation of the narrow and deep evaporation suppression topographic unit 3, and the bottom elevation difference was used to form a sand-prevention embankment at the connection between the two.

[0034] By designing the bottom elevation of the narrow-deep evaporation suppression topographic unit 3 to be higher than the bottom elevation of the outer sediment discharge channel of the water-sediment differentiation topographic unit 1, a natural elevation difference is formed at the junction of the two. This elevation difference constitutes a physical sediment control barrier. When water and sediment separate, the bedload sediment driven by gravity to slide into the depths of the outer concave bank, upon encountering this barrier, is unable to cross the barrier due to its lower gravitational potential energy and enter the higher-positioned narrow-deep evaporation suppression topographic unit 3 on the inner side. Thus, it is effectively blocked within the outer sediment discharge channel, further ensuring that the water entering the narrow-deep channel is relatively clean and improving the water quality of the intake.

[0035] The scheme was further optimized so that the main earthwork of the threshold overflow terrain unit 2 was derived from the in-situ earthwork generated by the excavation of the narrow and deep steam suppression terrain unit 3.

[0036] By employing the "earthwork balance" construction method, the large amount of earthwork generated from excavating and shaping the narrow and deep anti-evaporation terrain unit 3 is directly used to fill the adjacent threshold overflow terrain unit 2 (dividing embankment). This method achieves a balance between excavation and filling of the project earthwork within the region, avoiding long-distance transportation or external purchase of earthwork, greatly reducing project transportation costs and the impact on the surrounding environment, and significantly improving the economic efficiency and environmental friendliness of the entire system engineering implementation.

[0037] Further optimization of the scheme: a low potential energy discharge control port 5 is provided at the end of the system. The outlet shape of the low potential energy discharge control port 5 is configured to form a larger longitudinal gradient during the flood season, so as to increase the flow velocity and cooperate with the high water level to achieve self-dredging of the narrow and deep evaporation suppression terrain unit 3.

[0038] By setting a specially shaped low-potential-energy discharge control outlet 5 at the end of the system, such as a funnel-shaped or constricted outlet, a larger local longitudinal gradient (hydraulic slope) can be formed at the outlet during high water levels in the flood season. According to hydraulic principles, a larger gradient means a larger water flow driving force and velocity. The high-velocity water flow can generate a strong scouring effect on the bottom of the narrow and deep evaporation-suppressing topographic unit 3, thereby washing away any small amount of fine-grained silt that may remain during the dry season, achieving "self-dredging" of the deep channel and reducing the need for manual dredging in later maintenance.

[0039] The present invention also provides an adaptive flood and drought relief method for arid river channels based on the above system, comprising the following steps: S1. Active capture: Utilize the active capture terrain group upstream to straighten and converge the wandering river flow to the system inlet; S2. Topographic reshaping and sediment removal: During the dry season, the water flows into the water-sediment differentiation topographic unit 1. Under the gravity provided by the lateral slope, the bottom sediment is forced to slide to the depth of the outer concave bank. S3, Geometric Evaporation Suppression: During the dry season, fresh water is confined to the deep trenches of narrow and deep evaporation suppression terrain unit 3 for transport, thereby reducing evaporation by reducing the free water surface area; S4, Mutual Assistance and Transformation: When the water level rises above the top height of the threshold overflow terrain unit 2, the excess water overflows into the outer floodplain 4, while the flow velocity in the narrow and deep evaporation suppression terrain unit 3 increases, realizing the self-dredging of the channel.

[0040] By executing steps S1 to S4, a complete adaptive management of river water and sediment resources in arid regions is achieved. Step S1 ensures a stable inflow at the system inlet; Step S2 utilizes the constant gravity generated by reshaped topography to efficiently remove sediment at low flow velocities during the dry season, overcoming the bottlenecks of traditional technologies; Step S3 significantly reduces ineffective evaporation through geometric changes, conserving valuable water resources; and Step S4 achieves automatic, non-powered switching between flood and drought conditions through physical thresholds, ensuring flood control safety during flood season while transforming turbid water (sediment and water) into ecological resources. This method has a clear logic, and the synergistic effects of each step constitute an efficient and low-maintenance river management and utilization process.

[0041] Further optimize the scheme. In step S2, the lateral slope i c The value is set to 3% to 5% to ensure that, under low flow velocity during the dry season, the lateral gravity sliding component of the bottom sediment particles is greater than their static friction force on the riverbed.

[0042] By explicitly defining the lateral slope i of water-sediment differentiation topographic unit 1 during the implementation of the method. c Setting the critical range of 3% to 5% provides precise engineering parameters for the effective operation of the gravity sediment removal mechanism. This parameter setting ensures that gravity can become the core force driving sediment movement under specific hydrological conditions during the dry season. It makes the sediment removal process proactive and independent of unstable hydrodynamic forces, thus solidifying the technical feasibility of efficient sediment removal during the dry season at the methodological level.

[0043] Further optimize the scheme. In step S3, the depth-to-width ratio of the narrow-depth anti-evaporation terrain unit 3 shall not be less than 0.8 and shall be at least 5 times the typical depth-to-width ratio of a natural river channel.

[0044] By specifying in the methodology that the depth-to-width ratio of the narrow-depth evaporation-suppressing topographic unit 3 must be more than five times the typical value of a natural river channel, the design standard for "narrow-depth" evaporation suppression is quantified. This significantly increased depth-to-width ratio is the technical guarantee for a remarkable geometric evaporation suppression effect. It forcibly confines the water flow from its natural wide and shallow state into a deep channel with a small cross-section, which proportionally and significantly reduces the free water surface area for water-air contact, thereby ensuring that the expected evaporation suppression effect can be achieved at the methodological implementation level.

[0045] The adaptive flood and drought mitigation system and method for arid river channels based on terrain reshaping provided by this invention has the following overall implementation process and technical effects: During implementation, firstly, in the upstream section of a selected wandering river in an arid region, an active capture terrain group consisting of discontinuous groynes 11 and V-shaped water-binding dikes 12 is constructed to stabilize the inlet flow. Next, the river channel topography is reshaped to construct core functional units: a section of the bend is modified into a water-sediment differentiation terrain unit 1 with a bottom slope of 3%-5% towards the concave bank; a narrow and deep evaporation-suppressing terrain unit 3 with a significantly increased depth-to-width ratio is excavated on the inner convex bank, and the excavated soil is used to fill adjacent areas to form a threshold overflow terrain unit 2; the outer concave bank area is leveled or dredged into a wide and shallow outer floodplain 4; and a low-potential-energy discharge control outlet 5 is set at the end of the narrow and deep evaporation-suppressing terrain unit 3. After the system was built, during the dry season, the incoming flow was diverted by the V-shaped water-constricting dike 12 into the water-sediment differentiation topographic unit 1. Under the influence of gravity, the bottom sediment slid down the slope to the sediment discharge channel deep in the outer concave bank, while the surface clear water accumulated on the inner side and crossed the sand control embankment into the deep channel of the narrow and deep evaporation-suppressing topographic unit 3 for low-evaporation transport, thus achieving "clear water returning to the channel". During the flood season, when the water level exceeds the top of the dike of the threshold overflow topographic unit 2, it automatically overflows to the outer floodplain 4, where it discharges floodwater, settles sediment, and replenishes the ecosystem. At the same time, the flow velocity in the narrow and deep evaporation-suppressing topographic unit 3 increases due to the relative contraction of the water passage cross section. Combined with the effect of the low potential energy discharge control outlet 5 at the end, it achieves self-dredging of the channel bottom.

[0046] This invention overcomes the shortcomings of traditional bend-type sediment removal technology during the dry season through a gravity sliding mechanism, achieving highly efficient sediment removal under all operating conditions, especially at low flow velocities (the expected bottom bedload interception and discharge rate is greater than 90%), with virtually no need for manual dredging. By geometrically narrowing the water surface through a narrow and deep compound cross-section, it is expected to reduce free water surface evaporation loss by more than 75% compared to natural wide and shallow channels of the same flow rate. Utilizing the threshold overflow topographic unit 2 as a physical switch, adaptive switching between "water conservation and sediment transport" during the dry season and "flood discharge and sediment replenishment" during the flood season can be achieved without external power or human intervention, transforming floodwater and sediment into ecological resources. The upstream active capture topographic group ensures the stability of the water intake location and continuous water intake; the end design promotes self-dredging of the deep channel, reducing operation and maintenance costs. The earthwork balance construction method saves costs and minimizes environmental impact. In summary, this invention systematically solves the water-sediment contradiction and the problem of efficient water resource utilization in wandering rivers in arid areas through the innovative coupling of three core mechanisms: "gravity sediment removal, geometric evaporation suppression, and threshold scheduling."

[0047] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A terrain-reshaping-based adaptive flood and drought mitigation system for arid river channels, characterized in that, This includes four reshaped terrain units arranged in parallel and coupled along the direction of water flow. The four reshaped terrain units include: The water and sediment differentiation topographic unit (1) is configured as a curved channel. Its bottom plate is reshaped and has a transverse slope that slopes to the outer concave bank. This is used to drive the high sediment content water flow at the bottom layer to the outside under the dominance of gravity, so that the surface clear water accumulates to the inner convex bank. The narrow and deep evaporation suppression topographic unit (3) is connected to the inner convex bank diversion path of the water and sediment differentiation topographic unit (1). It adopts a narrow and deep compound cross-section structure with a depth-to-width ratio of not less than 0.8, which is used to collect and transport the stratified clear water. The outer floodplain (4) is located on the outer concave bank of the water-sediment differentiation topographic unit (1). It is reshaped into a wide and shallow riverbed to serve as a sediment discharge channel and a flood discharge and ecological replenishment area. The threshold overflow terrain unit (2) is located between the narrow and deep evaporation suppression terrain unit (3) and the outer floodplain (4), and its top elevation constitutes the physical threshold for flood-drought switching.

2. The terrain-reshaping-based adaptive flood and drought relief system for arid river channels according to claim 1, characterized in that, In the water-sediment differentiation topographic unit (1), the lateral slope i tilting towards the outer concave bank c The value ranges from 3% to 5%.

3. The terrain-reshaping-based adaptive flood and drought mitigation system for arid river channels according to claim 1, characterized in that, It also includes an active capture terrain group located upstream, which includes a discontinuous groynes (11) extending to the edge of the main channel swing zone and a V-shaped water-binding dike (12) connecting the ends of the groynes, which is arranged in a funnel shape in the plane.

4. The terrain-reshaping-based adaptive flood and drought relief system for arid river channels according to claim 3, characterized in that, The V-shaped water-binding diversion dike (12) adopts a variable porosity composite structure, including a dense seepage-proof body (12a) on the water-facing side and a permeable energy-dissipating body (12b) on the back side, and the dense seepage-proof body (12a) and the permeable energy-dissipating body (12b) are connected by multiple through-type tie rods.

5. The terrain-reshaping-based adaptive flood and drought relief system for arid river channels according to claim 1, characterized in that, The bottom elevation of the sand discharge channel on the outer side of the water and sediment differentiation topographic unit (1) is lower than the bottom elevation of the narrow and deep evaporation suppression topographic unit (3), and the sand control embankment is formed at the connection between the two by utilizing the difference in bottom elevation.

6. The terrain-reshaping-based adaptive flood and drought relief system for arid river channels according to claim 1, characterized in that, The main earthwork of the threshold overflow terrain unit (2) comes from the in-situ earthwork generated by excavating the narrow and deep anti-evaporation terrain unit (3).

7. The terrain-reshaping-based adaptive flood and drought relief system for arid river channels according to claim 1, characterized in that, The system is equipped with a low potential energy discharge control port (5) at the end. The outlet shape of the low potential energy discharge control port (5) is configured to form a larger longitudinal gradient during the flood season, so as to increase the flow velocity and cooperate with the high water level to achieve the self-dredging of the narrow and deep evaporation suppression terrain unit (3).

8. A method for adaptive flood and drought relief in arid river channels based on the system described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Active capture: Utilize the active capture terrain group upstream to straighten the wandering river and bring it to the system inlet; S2, Topographic Reshaping and Sediment Removal: During the dry season, water flows into the water-sediment differentiation topographic unit (1), and under the gravity provided by the transverse slope, the bottom sediment is forced to slide to the depth of the outer concave bank. S3, Geometric evaporation suppression: During the dry season, clean water is confined to the deep trench of the narrow and deep evaporation suppression terrain unit (3) for transport, thereby reducing evaporation by reducing the free water surface area; S4, Mutual Assistance and Transformation: When the water level rises above the top height of the threshold overflow terrain unit (2), the excess water overflows into the outer floodplain (4), and at the same time, the flow velocity in the narrow and deep evaporation suppression terrain unit (3) increases, realizing the self-dredging of the channel.

9. The adaptive flood and drought relief method for arid river channels according to claim 8, characterized in that, In step S2, the lateral slope i c The value is set to 3% to 5% to ensure that, under low flow velocity during the dry season, the lateral gravity sliding component of the bottom sediment particles is greater than their static friction force on the riverbed.

10. The adaptive flood and drought relief method for arid river channels according to claim 8, characterized in that, In step S3, the depth-to-width ratio of the narrow-depth-suppressing topographic unit (3) is not less than 0.8 and is at least 5 times the typical depth-to-width ratio of a natural river channel.

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