Self-adaptive combination scheme optimization method and system for flood control of drainage basins and regions

Abstract

The invention provides a self-adaptive combination scheme optimization method and system for flood control of drainage basins and areas. The areas comprise the upstream area, the midstream area and the downstream area of the whole drainage basin. The method comprises the following steps: for an upstream area of a drainage basin, obtaining a corresponding upstream flood control project measure combination scheme by taking a large water level reduction amplitude and a reduction of peak flood flow as principles; for a midstream area of the drainage basin, a corresponding midstream flood control project measure combination scheme is obtained according to the principles of large water level reduction amplitude, small population number affected by a submerged area and low project investment cost; for a downstream area of the drainage basin, a corresponding downstream flood control project measure combination scheme is obtained according to the principles of small submerging water depth, small population number affected by the submerging area and low project investment cost; forming an overall flood control project measure combination scheme; and selecting an overall flood control project measure combination scheme with the highest comprehensive benefit. The flood control scheme is adaptively selected based on natural geographical conditions and flood characteristics of different areas of the drainage basin, and the effectiveness of the flood control scheme is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flood prevention and disaster reduction, and specifically relates to a method and system for optimizing adaptive combination schemes for river basin and regional flood prevention. Background Art

[0002] At the river basin level, flood control work faces complex challenges. At present, the flood control system mainly relies on traditional dam construction and drainage systems. However, single flood control measures have gradually become insufficient and cannot effectively resist more complex flood situations. Considering the combination of flood control schemes in river basins and regions is an important way to improve the flood control capacity of river basins.

[0003] The existing flood control situation often has the following problems: many flood control measures are often only targeted at a specific area, such as the upstream, midstream or downstream, lacking overall system considerations, which can easily lead to local optimality and low overall benefits; at the same time, a unified flood control planning artificial experience is adopted for the upstream, midstream or downstream, lacking regional governance solutions; the existing urban flood control and disaster reduction system is still imperfect, and the lack of hydrological data is one of the weak links. Accurate flood information is not only the key to carrying out flood control and disaster reduction work, but also the basis for flood control hydrological analysis and calculation; existing flood control projects usually focus on short-term economic benefits, but ignore the long-term social benefits such as the impact on the population and environment of the flooded area.

[0004] The present invention explores the optimization method of adaptive combination schemes at the river basin and regional levels, flexibly adjusts flood control schemes, improves overall flood control capabilities, and develops an adaptive combination scheme optimization method for river basin and regional flood control, which has important practical significance. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned background technology, to provide a method and system for optimizing adaptive combination schemes for river basin and regional flood control, to fully consider the regional characteristics of the upper and middle reaches, and to realize the combination of engineering measures and non-engineering measures, thereby improving the effectiveness of flood control schemes.

[0006] The technical solution adopted by the present invention is: an adaptive combination scheme optimization method for flood control in a river basin or region, wherein the river basin refers to a single river basin; the region includes the upstream, midstream and downstream areas of the entire river basin;

[0007] The method comprises the following steps:

[0008] After judging that there is a flood risk in the basin,

[0009] For the upstream area of ​​the basin, the corresponding upstream flood control engineering measures combination plan is obtained based on the principles of maximizing the water level reduction and maximizing the reduction of flood peak flow;

[0010] For the midstream area of ​​the basin, the corresponding midstream flood control project measures combination plan is obtained based on the principles of maximizing the water level reduction, minimizing the number of people affected in the flooded area, and minimizing the project investment cost;

[0011] For the downstream area of ​​the basin, the corresponding downstream flood control project measures combination plan is obtained based on the principles of minimizing the flood depth, minimizing the number of people affected in the flooded area, and minimizing the project investment cost;

[0012] Select any one of the upstream flood control engineering measure combination schemes, any one of the midstream flood control engineering measure combination schemes and any one of the downstream flood control engineering measure combination schemes to form an overall flood control engineering measure combination scheme;

[0013] Select the overall flood control project measure combination plan with the highest comprehensive benefit; the comprehensive benefit includes: project flood control effect, project flood control risk and economic benefit;

[0014] The corresponding non-engineering measures are selected in combination with the selected overall flood control engineering measures combination scheme, so as to form the final flood control scheme in combination with the selected overall flood control engineering measures combination scheme.

[0015] In the above technical scheme, the process of judging the flood control risk of a river basin includes: establishing a hydrological and hydrodynamic model of the river basin; calculating the flood levels of the upstream, midstream and downstream areas based on the flood control objectives of the river basin and the hydrological and hydrodynamic model; if the flood level of any area in the upstream, midstream and downstream is greater than the design water level of the embankments on both sides, it is determined that there is a flood control risk in the river basin.

[0016] In the above technical scheme, the process of forming a combination of upstream flood control engineering measures includes:

[0017] The hydrological-hydrodynamic model is used to calculate the water level reduction and peak flow reduction in the upstream area after different single flood control measures are taken in the upstream area.

[0018] Several flood control measures with the largest water level reduction and several flood control measures with the largest reduction in peak flood flow are selected as a combination of upstream flood control engineering measures.

[0019] In the above technical scheme, the process of forming a combination of measures for midstream flood control projects includes:

[0020] The hydrological-hydrodynamic model is used to calculate the water level reduction in the middle reaches, the population affected in the flooded area, and the engineering investment after different single flood control measures are taken in the middle reaches.

[0021] Several flood control measures with the largest water level reduction, several flood control measures with a small population affected in the inundated area, and several flood control measures with the smallest engineering investment cost are selected as a combination of flood control project measures in the middle reaches.

[0022] In the above technical scheme, the process of forming a combination of downstream flood control engineering measures includes:

[0023] The hydrological-hydrodynamic model is used to calculate the flood depth, population affected by the flooding area, and engineering investment in the downstream area after different single flood control measures are taken in the midstream area.

[0024] Several flood control measures with the smallest inundation depth, several flood control measures with a small population affected in the inundation area, and several flood control measures with the smallest engineering investment cost are selected as a combination of downstream flood control engineering measures.

[0025] In the above technical scheme, the single flood control measures taken in the upstream area include: embankment projects, reservoir flood control projects or river regulation projects at a single location in the upstream area.

[0026] In the above technical scheme, the single flood prevention measures taken in the middle reaches include: embankment projects, river channel regulation projects, flood diversion projects and flood storage and detention area construction projects at single locations in the middle reaches.

[0027] In the above technical scheme, the single flood prevention measures taken in the middle reaches include: embankment projects, river channel improvement projects and flood storage and detention area construction projects at single locations in the downstream area.

[0028] In the above technical scheme, for the combined scheme of upstream, midstream and downstream flood control measures, the number of flood control measures in the combined scheme is minimized on the premise that the water levels in the corresponding areas meet the requirements of flood control planning standards after implementation.

[0029] In the above technical solution, the comprehensive benefit E 综合 The calculation is done using the following formula:

[0030] E 综合 =λ1E 水位降低 +λ2E 洪峰流量削减 -λ3E 淹没水深 -λ4E 影响人口 -λ5E 投资成本 +λ6E 工程效益

[0031]

[0032] In the formula, E 水位降低 It indicates the reduction of water level in the basin after adopting the overall flood control measures combination scheme; E 洪峰流量削减 It indicates the reduction of peak flow in the basin after adopting the overall flood control measures combination plan; E 淹没水深 It represents the flooding depth of the basin after adopting the overall flood control measures combination scheme, E 影响人口It represents the number of people affected by the flooded area of ​​the basin after the overall flood control measures are adopted, E 投资成本 E represents the engineering investment amount of the overall flood control measures combination plan, 工程效益 represents the engineering benefits of the basin after adopting the overall flood control measures combination scheme, λ i Represents the calculation weight coefficient of the corresponding indicator, where i=1,…,6.

[0033] In the above technical scheme, for the upstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes reservoir flood control projects, the non-engineering measures shall be flood control command and dispatch system and reservoir dispatch; if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans;

[0034] For the midstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans and floodplain management; if it includes flood storage and detention areas, the non-engineering measures shall be flood insurance;

[0035] For the downstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river channel regulation projects, the non-engineering measures correspond to floodplain management; if it includes flood storage areas, the non-engineering measures correspond to flood insurance

[0036] The non-engineering measures are implemented for the entire watershed.

[0037] The present invention also provides a basin- and regional-oriented adaptive combination scheme optimization system for flood control, which is used to implement the basin- and regional-oriented adaptive combination scheme optimization method described in the above technical solution.

[0038] The beneficial effects of the present invention are as follows: the present invention combines harm elimination with benefit promotion, takes into account the upper, middle and lower reaches, and comprehensively considers the main and tributary rivers, so as to focus on the different regions of the upper, middle and lower reaches, and sets different principles for each region, and selects several flood control measures in a targeted manner. The present invention is based on the actual needs of mainly storing water in the upper and middle reaches of the river and mainly discharging water in the lower reaches. The present invention disassembles the flood control tasks of the entire basin into separate flood control tasks in the upper and middle reaches, which are jointly undertaken by a variety of flood control projects to form a flood control engineering system, fully considering the special needs of different regions while effectively achieving the expected flood control goals. The present invention further combines several flood control measures from the perspective of engineering flood control effects, engineering flood control risks and economic benefits, to ensure that the selected overall flood control measures combination scheme can meet the overall needs of the basin as a whole, and improve the overall flood control capacity of the basin.

[0039] Furthermore, the present invention constructs a hydrological-hydrodynamic model, dynamically connects the hydrological model and the hydrodynamic model, effectively evaluates the flood control capacity of the basin, ensures the effective triggering of the flood control planning process, and at the same time, the hydrological-hydrodynamic model can reflect the impact of flood control measures on the basin, and provide evidence support for the planning of subsequent flood control measures. The hydrological model effectively solves the problem that the lack of hydrological data in some basins hinders the calculation of flood processes, and creates input conditions for the hydrodynamic model; the hydrodynamic model can fully reflect the impact of various engineering management measures in the basin on the floods and their propagation in the main and tributary rivers, and timely grasp the changing characteristics of flood levels, flow rates, etc. in the basin, thereby ensuring that the flood control measures finally adopted can meet the current and future flood control needs of the basin.

[0040] Furthermore, the present invention targets the characteristics of the upstream river basin, and taking into account the extent of water level reduction and the scheme for reducing peak flood flow, can accurately evaluate the impact of different flood control measures on the upstream water level, maximize the extent of water level reduction, effectively improve the upstream flood control capacity, and reduce the flow of excessive water from the upstream to the downstream, thereby reducing the risk of downstream floods.

[0041] Furthermore, the present invention targets the characteristics of the middle and lower reaches of the river basin, and considers the extent of water level reduction, inundation depth, the number of people affected by the inundation area, and the project investment plan in the middle and lower reaches to effectively improve the flood control capacity of the middle reaches while ensuring social benefits. Furthermore, the formed flood control measure combination plan minimizes the number of flood control measures on the premise that the water level of the river basin meets the flood control planning standard requirements after implementation, ensuring that the flood control measure combination plan can just meet the flood control planning standard requirements, avoiding taking too many flood control measures, and thus increasing the flood control cost.

[0042] Furthermore, taking separate levee projects, reservoir flood control projects or river channel regulation projects in the upper reaches can make full use of the turbulent characteristics of upstream floods to regulate reservoirs, while reducing the impact of excessive upstream water flows on the downstream, thereby reducing the overall flood risk; taking separate levee projects, river channel regulation projects, flood diversion projects and flood storage and detention area construction projects in the middle reaches can effectively block floods, protect residents and agricultural land in the middle reaches, help improve the region's disaster prevention and mitigation capabilities, establish flood storage and detention areas, and temporarily store floods, thereby lowering the downstream water level during the flood peak and reducing the impact of floods on the downstream area; taking separate levee projects, river channel regulation projects and flood storage and detention area construction projects in the downstream can protect farmland, villages and urban facilities to the greatest extent possible and ensure the safety of people's lives and property.

[0043] Furthermore, the present invention fully considers the comprehensive benefits of the combination scheme, comprehensively considers three evaluation indicators: engineering flood control effect, engineering flood control risk and economic benefit, and uses six items: water level reduction, peak flow reduction, flood depth, affected population, investment cost and engineering benefit as calculation indicators, to provide a reference for the comprehensive benefit evaluation of the basin flood control combination scheme.

[0044] Furthermore, the engineering measures and non-engineering measures of the present invention are combined to form a basin flood control plan, which can make up for the shortcomings of engineering measures in the face of more complex flood situations, provide technical support such as flood warning and flood control plan adjustment, reduce dependence on large-scale flood control engineering measures, and form a more efficient flood control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not constitute a limitation on the present invention.

[0047] The present invention provides a method for optimizing an adaptive combination scheme for flood control in a river basin or a region, comprising the following steps:

[0048] After judging that there is a flood risk in the basin,

[0049] For the upstream area of ​​the basin, the corresponding upstream flood control engineering measures combination plan is obtained based on the principles of maximizing the water level reduction and maximizing the reduction of flood peak flow;

[0050] For the midstream area of ​​the basin, the corresponding midstream flood control project measures combination plan is obtained based on the principles of maximizing the water level reduction, minimizing the number of people affected in the flooded area, and minimizing the project investment cost;

[0051] For the downstream area of ​​the basin, the corresponding downstream flood control project measures combination plan is obtained based on the principles of minimizing the flood depth, minimizing the number of people affected in the flooded area, and minimizing the project investment cost;

[0052] Select any one of the upstream flood control engineering measure combination schemes, any one of the midstream flood control engineering measure combination schemes and any one of the downstream flood control engineering measure combination schemes to form an overall flood control engineering measure combination scheme;

[0053] Select the overall flood control project measure combination plan with the highest comprehensive benefit; the comprehensive benefit includes: project flood control effect, project flood control risk and economic benefit;

[0054] The corresponding non-engineering measures are selected in combination with the selected overall flood control engineering measures combination scheme, so as to form the final flood control scheme in combination with the selected overall flood control engineering measures combination scheme.

[0055] The principle of the present invention is further explained below with reference to specific embodiments.

[0056] like Figure 1As shown, the present invention provides a method for optimizing an adaptive combination scheme for flood control in a river basin or a region, wherein the river basin refers to a single river basin; the region includes the upstream, midstream and downstream areas of the entire river basin;

[0057] The method comprises the following steps:

[0058] Step 1: Establish a hydrological-hydrodynamic model for the basin;

[0059] The hydrological-hydrodynamic model includes the input conditions of the hydrological-hydrodynamic model, the connection between the hydrological model and the hydrodynamic model, and the principle of the hydrological-hydrodynamic model.

[0060] The input conditions of the hydrological-hydrodynamic model include:

[0061] Hydrological model input conditions: sub-basin information, rainfall data, and hydrological model parameters.

[0062] The connection between the hydrological model and the hydrodynamic model: the information of the sub-basins of the basin, which uses point sources and distributed sources to input the runoff generated by rainfall (i.e., the output of the rainfall-runoff model) as the boundary into the hydrodynamic model.

[0063] Input conditions of the hydrodynamic model: research scope, cross-section data, boundary conditions (upstream, downstream, and lateral inflow boundaries), river roughness, and cross-river buildings.

[0064] The principle of the hydrological-hydrodynamic model is based on the water flow (HD) and rainfall-runoff (RR) models in the MIKE11 model.

[0065] (1) HD model

[0066] The HD model is the basis of the MIKE11 simulation system, which solves the mass conservation and momentum conservation equations along the cross-sectional area, namely the Saint-Venant equations:

[0067]

[0068] Where: Q is the cross-sectional flow, A is the cross-sectional area, q is the lateral inflow, R is the hydraulic (or resistance) radius, and C is the coefficient C = R 1 / 6 n -1 , n is the roughness of the river channel, a is the momentum correction coefficient, g is the acceleration of gravity, h is the water level of the section, and x and t are the position and time coordinates.

[0069] The main input parameters of the HD model include the mileage of the river and its interconnection, the river section, the roughness of the river, and the boundary conditions such as water level and flow. The equation system is discretized using the 6-point Abbott central difference format, and the discretized linear equation system is solved using the two-way elimination format to simulate the unsteady flow in the open channel river network. The output result is a time series of water level and flow.

[0070] (2)RR model

[0071] When the measured runoff (flow) data of the basin is less, in order to provide boundary conditions for the HD model, it is necessary to establish the RR (Rainfall-Runoff) model, and the SCS (Soil Consernation Service) model calculation method in the UHM model of MIKE11 is selected.

[0072] The basic principle of the SCS method is as follows: For a rainfall, the runoff volume P e is always less than the total rainfall P, while the amount of water infiltrating into the soil F a It is always less than the maximum soil water holding capacity S. Due to the initial loss I after rainfall a , so the maximum possible flow rate is PI a .

[0073] The SCS loss model assumes that the ratio of the loss to the maximum water holding capacity of the soil is equal to the ratio of the runoff to the maximum possible runoff, that is:

[0074]

[0075] According to the law of conservation of mass

[0076] P=I a +F a +P e (1.4)

[0077] Substituting equation (1.4) into equation (1.3) yields:

[0078]

[0079] According to a lot of rainfall data, a The empirical relationship is:

[0080] I a =0.2S (1.6)

[0081] Substituting equation (1.6) into equation (1.5) we have:

[0082]

[0083] For S, a relationship is established with the dimensionless number CN (Curve Number, usually ranging from 0 to 100) that characterizes the land use of the catchment area:

[0084] S=(1000 / CN-10)×25.4(mm) (1.8)

[0085] Since the actual runoff generation process is also affected by the initial soil moisture content, three initial soil moisture contents (AMC) are considered in the model, namely:

[0086] AMC(Ⅰ): Dry and close to the wilting point;

[0087] AMC(Ⅱ): average wetness close to field water content;

[0088] AMC(Ⅲ): close to saturated water content.

[0089] At the same time, the CN parameters given in the model are for the case where the underlying surface is in AMC (Ⅱ). The equivalent CN of the underlying surface of AMC (Ⅱ) in the case of AMC (Ⅰ) and AMC (Ⅲ) are:

[0090]

[0091] Combining equations (1.7) and (1.8), it can be seen that when the CN number is large, S is small, and the corresponding basin runoff is large. At the same time, according to equations (1.7) and (1.8), under the condition that the catchment CN is given, the runoff P can be explicitly calculated. e .

[0092] Step 2: Calibration and verification of hydrological-hydrodynamic model;

[0093] The calibration and validation of the hydrological-hydrodynamic model is achieved through the following methods:

[0094] Calibration and verification data selection:

[0095] According to the hydrological data and flood situations in the basin over the years, and taking into account factors such as changes in the flow capacity of the basin's rivers, two specific periods of rainstorm and flood processes were selected as the calibration and verification periods of the hydrological and hydrodynamic model to test the model's simulation accuracy of water level and flow processes.

[0096] Model calibration and verification results analysis:

[0097] Select one of the rainstorm and flood process data and input it into the hydrological-hydrodynamic model to calibrate the water level and flow process of the measuring station. Compare the fluctuation trend, phase and peak value of the model's water level and flow process with the measured water level and flow process. If the calibration result is consistent with the measured value, it proves that the simulation result is more accurate.

[0098] Select another rainstorm and flood process data and input it into the hydrological-hydrodynamic model to obtain the water level and flow process of the measuring station for verification. Compare the fluctuation trend, phase and peak value of the model's water level and flow process with the measured water level and flow process. If the result is consistent with the measured value, it proves that the calibration result is reliable.

[0099] If the simulation error is large, adjust the CN number and river channel roughness used for calibrating the hydrological model until the simulation results are satisfactory.

[0100] Step 3: Calculation and evaluation of the current flood control capacity of the basin;

[0101] The hydrological-hydrodynamic mathematical model that has been calibrated and verified is used to calculate the basin flood level by selecting the corresponding frequency of rainstorm and flood conditions according to the flood control target of the basin. The flood control target of the basin can be a flood that occurs once in a hundred years or once in 50 years. If the flood control target is a flood that occurs once in 50 years, the flood data with a hydrological frequency of once in 50 years in the historical data is selected for simulation calculation, that is, the flood level of the basin is calculated using the rainstorm and flood conditions of a typical annual flood in 50 years.

[0102] Compare the calculated basin flood level with the design water level of the levees on both sides (or the current ground elevation), analyze the current flood control capacity, and determine whether it is necessary to formulate a basin flood control plan. If the basin flood level is greater than the design water level of the levees on both sides of the basin to be planned, it is determined that a basin flood control plan needs to be formulated, and subsequent steps are performed to obtain a combination of flood control measures for the basin.

[0103] Step 4: Obtain a combination of flood control measures and engineering solutions.

[0104] The present invention is aimed at the flood control engineering measures adopted in different regions. According to the natural geographical conditions of the basin, the characteristics of floods and sediments, and the socio-economic conditions, the present invention combines harm elimination with benefit promotion, takes into account the upper, middle and lower reaches, and comprehensively plans the main and tributary rivers. Generally, the upper and middle reaches of the river are mainly for storage, while the lower reaches are mainly for discharge. The flood control task of a river or a region is usually undertaken by a combination of multiple flood control projects to form a flood control engineering system to achieve the expected flood control goals.

[0105] Different areas in the same basin generally have different characteristics and needs:

[0106] Upstream: There are usually steep terrain and fast water flow in the upstream. After heavy rainfall, the water flow increases rapidly, leading to an increased risk of flash floods. Therefore, measures such as embankment projects can be used to timely intercept and guide water flow to reduce the damage to the surrounding areas; the upstream area is suitable for the construction of reservoirs, which can not only store floods and regulate flow, but also provide a stable water source and flood control guarantee for the downstream. As a storage facility, the reservoir can reduce the peak flow of floods and help alleviate the impact of floods on the middle and downstream areas; the upstream river channel often changes due to upstream erosion and sedimentation. River channel regulation can improve the water flow capacity and reduce the risk of floods.

[0107] Midstream: The midstream is the area that receives floods downstream. While ensuring the flood control capacity of the midstream, it is also necessary to reduce the flood control pressure in the downstream. Measures such as embankment projects, river channel improvement projects, and flood diversion projects can be taken to meet the needs of the midstream. Flood storage areas provide a buffer for the midstream and downstream areas, effectively protecting residents, agriculture, and infrastructure, and ensuring the flexibility of flood management.

[0108] Downstream: The flood control projects in the downstream of the basin mainly consider the overall flood control and the flood control needs of key areas. In order to achieve these goals, the construction of basin control reservoir projects can be accelerated to give full play to their effective flood control and peak shifting functions, and reduce the downstream flood control pressure. At the same time, dangerous reservoirs can be strengthened in areas where floods and waterlogging disasters frequently occur, and the flood control capacity of existing control reservoir projects can be consolidated and improved.

[0109] Based on the above differences between the upper and middle reaches, different flood control engineering schemes are generated in different areas according to the following different combination principles:

[0110] Upstream: The hydrological-hydrodynamic model is used to calculate the extent to which the water level in the upstream area is reduced and the magnitude of the flood peak flow is reduced after different single flood control measures are taken in the upstream area;

[0111] Several flood control measures with the largest water level reduction and several flood control measures with the largest reduction in peak flood flow are selected as a combination of upstream flood control engineering measures.

[0112] Midstream: The hydrological-hydrodynamic model is used to calculate the water level reduction in the midstream area, the number of people affected by the flooding area, and the engineering investment after different single flood control measures are taken in the midstream area.

[0113] Several flood control measures with the largest water level reduction, several flood control measures with a small population affected in the inundated area, and several flood control measures with the smallest engineering investment cost are selected as a combination of flood control project measures in the middle reaches.

[0114] Downstream: The hydrological-hydrodynamic model is used to calculate the flood depth, population affected by the flooding, and engineering investment in the downstream area after different single flood control measures are taken in the midstream area;

[0115] Several flood control measures with the smallest inundation depth, several flood control measures with a small population affected in the inundation area, and several flood control measures with the smallest engineering investment cost are selected as a combination of downstream flood control engineering measures.

[0116] Select any upstream flood control engineering measure combination scheme, any midstream flood control engineering measure combination scheme and any downstream flood control engineering measure combination scheme to form an overall flood control engineering measure combination scheme. Traverse all possible combinations to form several different overall flood control engineering measure combination schemes.

[0117] Single flood control measures taken in the upstream area include: embankment projects, reservoir flood control projects or river regulation projects at a single location in the upstream area.

[0118] The individual flood prevention measures adopted in the mid-stream area include: embankment projects at individual locations in the mid-stream area, river regulation projects, flood diversion projects and flood storage and detention area construction projects.

[0119] The individual flood prevention measures adopted in the midstream area include: embankment projects at individual locations in the downstream area, river regulation projects and flood storage and detention area construction projects.

[0120] The number of flood control measures in the combination scheme of flood control measures in the upper, middle and lower reaches shall be determined according to the following principles: based on the current urban flood control status, flood control capacity and urban development needs, the combination scheme of flood control measures for the corresponding area shall be formed to minimize the number of flood control measures in the combination scheme, on the premise that the water level in the area meets the requirements of flood control planning standards after implementation.

[0121] The hydrological-hydrodynamic model calculates the water level of the corresponding area after taking various combinations of flood control measures, ensuring that the combination of flood control measures in the area can just meet the corresponding flood control planning standard requirements, avoiding taking too many flood control measures and thus increasing flood control costs.

[0122] Step 5: Evaluate the comprehensive benefits of each combination of flood control measures;

[0123] A comprehensive benefit evaluation model for flood control planning schemes is established with engineering flood control effects, engineering flood control risks and economic benefits as the evaluation index system, and the maximization of the comprehensive benefits of the overall flood control planning scheme is taken as the objective function.

[0124] The comprehensive benefit E 综合 The calculation is done using the following formula:

[0125] E 综合 =λ1E水位降低 +λ2E 洪峰流量削减 -λ3E 淹没水深 -λ4E 影响人口 -λ5E 投资成本 +λ6E 工程效益

[0126]

[0127] In the formula, E 水位降低 It indicates the reduction of water level in the basin after adopting the overall flood control measures combination scheme; E 洪峰流量削减 It indicates the reduction of peak flow in the basin after adopting the overall flood control measures combination plan; E 淹没水深 It represents the flooding depth of the basin after adopting the overall flood control measures combination scheme, E 影响人口 It represents the number of people affected by the flooded area of ​​the basin after the overall flood control measures are adopted, E 投资成本 E represents the engineering investment amount of the overall flood control measures combination plan, 工程效益 represents the engineering benefits of the basin after adopting the overall flood control measures combination scheme, λ i Represents the calculation weight coefficient of the corresponding indicator, where i=1,…,6.

[0128] The indicators of engineering flood control effects and risks (water level reduction, peak flow reduction, flood depth, and population affected in the flooded area) are calculated under different engineering schemes through the established hydrological-hydrodynamic model; the investment cost indicators in the economic benefits are calculated through the scheme design scale and the unit price of engineering measures, and the engineering benefit indicators are calculated based on the total value of property protected by the scheme.

[0129] Using the analytic hierarchy process to determine the index weight coefficient λ i , the process is as follows:

[0130] Step A, taking water level reduction, flood peak flow reduction, flood depth, population impact, investment cost, and project benefits as evaluation indicators, taking comprehensive benefits as the target layer and flood control measures as the solution layer, a hierarchical structure is constructed;

[0131] Step B, compare the importance of different evaluation indicators in pairs, and construct a judgment matrix based on the results of the pairwise comparison, where a scale of 1 to 9 is used to represent the relative importance of the evaluation indicators. ij is the importance of factor i relative to factor j;

[0132]

[0133] Step C, perform consistency check on the judgment matrix: calculate the CI and the average random consistency index RI for measuring the inconsistency of the judgment matrix; RI is obtained by looking up the table, and the CI calculation formula is:

[0134]

[0135] In the formula, λ max (A) is the absolute value eigenvalue of the pairwise contrast matrix A, and the pairwise contrast matrix A = (a pq )n×n; n is the order of the pairwise comparison matrix A; calculate the ratio of the inconsistency index CI and the average random consistency index RI to obtain the random consistency ratio CR of the judgment matrix;

[0136] When CR < 0.1, the judgment matrix is ​​judged to have satisfactory consistency, or its inconsistency is acceptable;

[0137] When CR ≥ 0.1, the judgment matrix is ​​adjusted until the judgment matrix reaches satisfactory consistency;

[0138] Step D, when the judgment matrix satisfies CR<0.1, the weights W=[λ1,λ2,...,λ6] of the six evaluation indicators are solved; wherein each column vector of the weight W is calculated by the canonical column average method, specifically: each column vector of the pairwise comparison matrix A is normalized respectively; the normalized column vector is summed and normalized with the corresponding row vector, and the value of the column vector finally obtained is the relative weight.

[0139] The water level reduction is calculated using the following formula:

[0140]

[0141] Where n is the number of water level stations with lowered water levels after the implementation of the overall flood control measures combination plan. is the water level at the ith station before the implementation of the overall flood control measures combination plan, is the water level at the ith station after the implementation of the overall flood control measures combination plan; the above parameters are calculated by the hydrological-hydrodynamic model.

[0142] The peak flow reduction size E 洪峰流量削减 The calculation is done using the following formula:

[0143]

[0144] Where n is the number of reservoirs in the basin, is the peak flow of the ith reservoir after the implementation of the overall flood control measures combination scheme, is the peak flow of the ith reservoir before the implementation of the overall flood control measures combination plan; the above parameters are calculated by the hydrological-hydrodynamic model.

[0145] E 淹没水深It is obtained from the overall flood control measures combination scheme after the hydrological-hydrodynamic model calculation simulation in the flooded area after the water level is raised; E 影响人口 is the number of residents within the flooded area; E 投资成本 Cost estimation is carried out based on the engineering quantity, operation and management costs, etc. of the engineering measures.

[0146] The project benefits are calculated using the following formula:

[0147] E 工程效益 =E 直接效益 +E 间接效益

[0148] In the formula, E 直接效益 It represents direct benefits, which is calculated by multiplying the total value of property after the implementation of the overall flood control measures combination plan by the property protection rate; E 间接效益 Indirect benefits are calculated at 20% of direct benefits. Direct benefits refer to the reduction in losses caused by protecting the main urban properties, residents' fixed properties and farmland in the dam area; indirect benefits refer to the indirect benefits brought about by the implementation of engineering measures in protecting the safety of people's lives and property in the local area, maintaining social stability and promoting economic development.

[0149] Step 6: Obtain non-engineering flood control solutions and combine them with the selected overall flood control engineering measures combination solution to form the final flood control solution.

[0150] For the upstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes reservoir flood control projects, the non-engineering measures shall be flood control command and dispatch system and reservoir dispatch; if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans;

[0151] For the midstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans and floodplain management; if it includes flood storage and detention areas, the non-engineering measures shall be flood insurance;

[0152] For the downstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river regulation projects, the non-engineering measures corresponding to it shall be floodplain management; if it is a flood storage area, the non-engineering measures corresponding to it shall be flood insurance.

[0153] The non-engineering measures are implemented for the entire watershed.

[0154] The engineering measures adopted by the present invention specifically include:

[0155] ① Embankment engineering: Embankment engineering refers to water retaining structures built along rivers, canals, lakes, coasts or the edges of flood-carrying areas, flood diversion areas, and reclamation areas. When the water level at the flood control point calculated above is higher than the current elevation of water retaining structures along rivers, canals, lakes, coasts, etc., it is necessary to take this engineering measure to build and heighten and reinforce the embankment engineering.

[0156] ② River regulation project: engineering measures taken to stabilize the river channel, reduce the wandering range of the main channel, and improve the river boundary conditions and water flow patterns. When a large number of houses are built on both sides of the river channel and water-blocking buildings occupy the river section, causing serious water blockage, this engineering measure is needed to regulate the river channel.

[0157] ③ Flood diversion project: Flood diversion project is a flood control measure to ensure the safety of the protection area by diverting flood water from the river. If the discharge capacity of a river is insufficient, but the flood discharge capacity of the adjacent river is sufficient, or if there is no flood, the flood can be diverted upstream of the river section with insufficient flood discharge capacity and discharged into the adjacent river through the flood diversion channel;

[0158] ④ Reservoir flood control project: measures to use the flood control storage capacity of the reservoir to regulate flood water to reduce the losses caused by floods downstream. The flood volume exceeds the storage capacity and the terrain and geological conditions are suitable for the construction of reservoirs.

[0159] ⑤Flood storage and detention area: refers to the low-lying areas and lakes outside the back water surface of the river embankment, including the diversion outlet, which are used to temporarily store flood water.

[0160] The non-flood control engineering measures adopted in the present invention include:

[0161] ①Flood control command and dispatch system: It is a comprehensive system integrating information collection, analysis and processing, decision-making and command and dispatch. Its main goal is to carry out flood control and drought relief work by scientifically dispatching human, material and financial resources;

[0162] ② Flood prevention plan: a general term for plans to prevent river floods (including major floods), mountain torrents (referring to mountain torrents and mud-rock flow disasters caused by rainfall), typhoon storm surge disasters, etc., formulated by local people's governments at or above the county level with flood prevention and control tasks based on comprehensive basin planning, actual conditions of flood control projects and national flood control standards; ③ Flood forecasting and scheduling: a commonly used flood optimization scheduling method, which predicts floods that may occur in the future by establishing a model of meteorological and hydrological data. The forecast results can be used as a basis for decision makers to make scheduling decisions, so that corresponding measures can be taken in time to reduce the impact of floods. When forecasting floods, it is necessary to take into account the influence of factors such as rainfall, soil moisture content, and topography to improve the accuracy and reliability of the forecast;

[0163] ③ Reservoir dispatching: It is a technical management method for controlling the use of reservoirs. It uses the reservoir's storage capacity to store and discharge the runoff in a planned manner according to the actual water storage situation and hydrological forecast. Under the premise of ensuring the safety of the project, it dispatches according to the priority of the tasks undertaken by the reservoir and the principle of comprehensive utilization of water resources to achieve the purpose of flood control and benefit development, and to meet the needs of various sectors of the national economy to the greatest extent possible.

[0164] ④Floodplain management: mainly to manage areas where floods may occur in order to reduce the losses caused by flood disasters. It is necessary to formulate corresponding laws and regulations based on zoning to manage floodplains, maintain their functions of flood discharge and retention, and make overall arrangements for land use. It is also necessary to restrict economic and social development plans that are not compatible with flood threats and take necessary measures to reduce flood losses;

[0165] ⑤Flood insurance: Flood insurance is a special form of property insurance that aims to provide financial compensation for the property losses of the policyholder or insured caused by floods. This type of insurance transforms the uncertain, unstable and huge risk of disaster losses into certain, stable and small expenses. Flood insurance is divided into two forms: voluntary insurance and compulsory insurance.

[0166] The principle of the present invention is further explained below with reference to specific embodiments.

[0167] The application scenario of the specific embodiment is the GH basin, including the main stream GH, tributaries LTH and HGH, which is also of guiding significance for flood control planning in other basins. The present invention provides an adaptive combination scheme optimization method for basin and regional flood control, including the following steps:

[0168] Step 1: Establishment of hydrological-hydrodynamic model;

[0169] The input conditions of the hydrological model are as follows: the sub-basin information includes the division range, area, inflow river channel, inflow point starting pile number, inflow point ending pile number, and hydraulic length; the rainfall data is the average of the heavy rains at three typical rainfall stations, SHQ station, BD station, and DQ station, as the surface heavy rain; the hydrological model parameter is the CN number that reflects the land use. The CN number needs to be adjusted and determined based on the model calibration calculation results. After calibration, the CN values ​​of the GH sub-basin are concentrated between 55 and 90.

[0170] Connection between the hydrological model and the hydrodynamic model: The information of the 12 sub-basins of the GH basin is combined with the hydraulic model to input the runoff generated by rainfall (i.e., the output of the rainfall-runoff model) as the boundary into the hydrodynamic model using point sources and distributed sources.

[0171] Input conditions of the hydrodynamic model: The research scope covers three rivers, of which GH is 52.2 km long, HGH is 15.2 km long, and LTH is 15.6 km long; the cross-section data are measured river cross-sections, of which GH has a total of 62 cross-sections with a cross-section spacing of about 800 m, LTH has a total of 30 cross-sections with a cross-section spacing of about 500 m, and HGH has a total of 26 cross-sections with a cross-section spacing of about 600 m; the boundary conditions include: the upstream boundary is the NC reservoir discharge process and the SML reservoir discharge process, The discharge process of the two reservoirs is obtained according to the corresponding reservoir scheduling and operation procedures or measured discharge data. The downstream boundary is the water level process of the SZ station as the downstream boundary condition of the model, and the lateral inflow boundary is the runoff process of the 12 sub-basins of the GH basin calculated by the hydrological model; the river roughness is calibrated and verified according to the hydrological-hydrodynamic model, and the river roughness of the simulated river section is between 0.025 and 0.028; the cross-river buildings are mathematical models of cross-river buildings such as bridges, rubber dams, sluice gates and power stations in the GH basin.

[0172] Step 2: Calibration and validation of the hydrological-hydrodynamic model;

[0173] Calibration and verification data selection:

[0174] According to the hydrological data of the GH basin over the years, as well as the flood encounters of GH and FTH, and taking into account factors such as the changes in the flow capacity of the river channels in the GH basin, the heavy rain and flood process from July 13 to July 15, 2010 was selected as the calibration period of the hydrological-hydrodynamic model, and the heavy rain and flood process from June 13 to June 15, 2011 was selected as the verification period of the hydrological-hydrodynamic model.

[0175] Step 3: Calculation and evaluation of the current flood control capacity of the basin;

[0176] Using the calibrated and verified hydrological-hydrodynamic mathematical model, the corresponding frequency of rainstorm and flood conditions are selected according to the flood control objectives of the XN basin to calculate the basin flood level;

[0177] The calculated flood level in the basin is compared with the design water level of the levees on both sides (or the current ground elevation). The comparison results show that the overall flood control capacity of the GH basin is between 10 and 20 years, which is quite different from the flood control standard of 50 years. It is necessary to formulate a basin flood control plan. The evaluation results are shown in Table 2.

[0178] Left Bank Flood control capabilities right bank Flood control capabilities XX dike Once in 20 years Below the XX River Once in 10 years X Bay Section Once in 10 years XX dike Once in 20 years XX Bridge to XX Bridge Once in 10 years XX Bridge to XX Bridge Once in 10 years XX dike Once in 20 years XX dike Once in 20 years XX dike Once in 10 years XXX Company to X Bridge Hydrological Station Section Once in 10 years XX urban embankment Once in 10 years X-Dyke Once in 10 years Section from XX Bridge to XX Park Once in 10 years XX Bay Dike Once in 10 years

[0179] Table 2 Evaluation of flood control capacity of each section of XN urban area

[0180] Step 4: Obtain a combination of flood control measures and engineering solutions.

[0181] Different flood control engineering schemes are generated in different areas according to different combination principles in the upper, middle and lower reaches of the GH basin:

[0182] Select any upstream flood control engineering measure combination scheme, any midstream flood control engineering measure combination scheme and any downstream flood control engineering measure combination scheme to form an overall flood control engineering measure combination scheme. Traverse all possible combinations to form several different overall flood control engineering measure combination schemes.

[0183] The number of flood control measures in the combination scheme of flood control measures in the upper, middle and lower reaches is determined according to the following principles: Based on the current flood control status and flood control capacity of the upper, middle and lower reaches of the GH basin and the needs of urban development, the combination scheme of flood control measures for the corresponding area is formed to minimize the number of flood control measures in the combination scheme on the premise that the water level in the area meets the requirements of flood control planning standards after implementation.

[0184] The hydrological-hydrodynamic model calculates the water level of the corresponding area after taking various combinations of flood control measures, ensuring that the combination of flood control measures in the area can just meet the corresponding flood control planning standard requirements, avoiding taking too many flood control measures and thus increasing flood control costs.

[0185] Step 5: Evaluate the comprehensive benefits of each overall flood control measure combination scheme, and select the GH basin flood control planning scheme with comprehensive results. Select the overall flood control engineering measure combination scheme with the highest comprehensive benefits; select corresponding non-engineering measures in combination with the selected overall flood control engineering measure combination scheme, and then combine them with the selected overall flood control engineering measure combination scheme to form the final flood control plan.

[0186] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. An adaptive combination scheme optimization method for river basin and regional flood control, characterized by: The following steps are involved: After judging that there is a flood risk in the basin, For the upstream area of ​​the basin, the corresponding upstream flood control engineering measures combination plan is obtained based on the principles of maximizing the water level reduction and maximizing the reduction of flood peak flow; For the midstream area of ​​the basin, the corresponding midstream flood control project measures combination plan is obtained based on the principles of maximizing the water level reduction, minimizing the number of people affected in the flooded area, and minimizing the project investment cost; For the downstream area of ​​the basin, the corresponding downstream flood control project measures combination plan is obtained based on the principles of minimizing the flood depth, minimizing the number of people affected in the flooded area, and minimizing the project investment cost; Select any one of the upstream flood control engineering measure combination schemes, any one of the midstream flood control engineering measure combination schemes and any one of the downstream flood control engineering measure combination schemes to form an overall flood control engineering measure combination scheme; Select the overall flood control project measure combination plan with the highest comprehensive benefit; the comprehensive benefit includes: project flood control effect, project flood control risk and economic benefit; The corresponding non-engineering measures are selected in combination with the selected overall flood control engineering measures combination scheme, so as to form the final flood control scheme in combination with the selected overall flood control engineering measures combination scheme.

2. The method according to claim 1, characterized in that: The process of judging the flood risk of a river basin includes: establishing a hydrological and hydrodynamic model of the river basin; calculating the flood levels of the upstream, midstream and downstream areas based on the flood control objectives of the river basin and the hydrological and hydrodynamic model; if the flood level of any area in the upstream, midstream or downstream is greater than the design water level of the embankments on both sides, it is determined that the river basin has a flood risk.

3. The method according to claim 1, characterized in that: The process of developing a portfolio of upstream flood control engineering measures includes: The hydrological-hydrodynamic model is used to calculate the water level reduction and peak flow reduction in the upstream area after different single flood control measures are taken in the upstream area. Several flood control measures with the largest water level reduction and several flood control measures with the largest reduction in peak flood flow are selected as a combination of upstream flood control engineering measures.

4. The method according to claim 1, characterized in that: The process of forming a combination of midstream flood control engineering measures includes: The hydrological-hydrodynamic model is used to calculate the water level reduction in the middle reaches, the population affected in the flooded area, and the engineering investment after different single flood control measures are taken in the middle reaches. Several flood control measures with the largest water level reduction, several flood control measures with a small population affected in the inundated area, and several flood control measures with the smallest engineering investment cost are selected as a combination of flood control project measures in the middle reaches.

5. The method according to claim 1, characterized in that: The process of developing a portfolio of downstream flood control engineering measures includes: The hydrological-hydrodynamic model is used to calculate the flood depth, population affected by the flooding area, and engineering investment in the downstream area after different single flood control measures are taken in the midstream area. Several flood control measures with the smallest inundation depth, several flood control measures with a small population affected in the inundation area, and several flood control measures with the smallest engineering investment cost are selected as a combination of downstream flood control engineering measures.

6. The method according to claim 3, characterized in that: Single flood control measures taken in the upstream area include: embankment projects, reservoir flood control projects or river regulation projects at a single location in the upstream area.

7. The method according to claim 4, characterized in that: The individual flood prevention measures adopted in the mid-stream area include: embankment projects at individual locations in the mid-stream area, river regulation projects, flood diversion projects and flood storage and detention area construction projects.

8. The method according to claim 4, characterized in that: The individual flood prevention measures adopted in the midstream area include: embankment projects at individual locations in the downstream area, river regulation projects and flood storage and detention area construction projects.

9. The method according to claim 3, characterized in that: For the combined flood control measures for the upstream, midstream and downstream, the number of flood control measures in the combined scheme should be minimized, provided that the water levels in the corresponding areas meet the requirements of the flood control planning standards after implementation.

10. The method according to claim 1, characterized in that: The comprehensive benefit E 综合 The calculation is done using the following formula: E 综合 =λ1E 水位降低 +λ2E 洪峰流量削减 -λ3E 淹没水深 -λ4E 影响人口 -λ5E 投资成本 +λ6E 工程效益 In the formula, E 水位降低 It indicates the reduction of water level in the basin after adopting the overall flood control measures combination scheme; E 洪峰流量削减 It indicates the reduction of peak flow in the basin after adopting the overall flood control measures combination plan; E 淹没水深 It represents the flooding depth of the basin after adopting the overall flood control measures combination scheme, E 影响人口 It represents the number of people affected by the flooded area of ​​the basin after the overall flood control measures are adopted, E 投资成本 E represents the engineering investment amount of the overall flood control measures combination plan, 工程效益 represents the engineering benefits of the basin after adopting the overall flood control measures combination scheme, λ i Represents the calculation weight coefficient of the corresponding indicator, where i=1,…,6.

11. The method according to claim 1, characterized in that: For the upstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes reservoir flood control projects, the non-engineering measures shall be flood control command and dispatch system and reservoir dispatch; if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans; For the midstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river regulation projects, the non-engineering measures shall be flood control plans and floodplain management; if it includes flood storage and detention areas, the non-engineering measures shall be flood insurance; For the downstream flood control measures combination scheme in the selected overall flood control measures combination scheme: if it includes embankment projects and river channel regulation projects, the non-engineering measures correspond to floodplain management; if it includes flood storage areas, the non-engineering measures correspond to flood insurance The non-engineering measures are implemented for the entire watershed.

12. An adaptive combination scheme optimization system for river basin and regional flood control, characterized by: A method for optimizing the adaptive combination scheme for river basin and regional flood control as described in any one of claims 1-11.

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