Green roof rainfall runoff unit line simulation method and system

Abstract

The invention discloses a green roof rainfall runoff unit line simulation method and a green roof rainfall runoff unit line simulation system, which are characterized in that a runoff result of a green roof under a specific rainfall event is calculated by establishing a green roof rainfall runoff unit line model on the basis of rainfall runoff data monitored in real time. Comprising the steps of obtaining physical parameters of a green roof; determining the maximum retention volume of the matrix soil layer before rainfall; the rainfall runoff process is monitored in real time; determining runoff production time according to the relationship between the accumulated rainfall and the initial loss amount; a unit line model of the rainfall runoff of the green roof is constructed, the response relation of runoff processes under different rainfall processes is calculated and obtained based on the model, and output results comprise the total runoff amount, the flow process, the peak flow and the like. According to the invention, the rainfall runoff process of the green roof can be accurately simulated, and theoretical basis and technical support are provided for urban rainwater management and green roof design.

Description

Technical Field

[0001] The invention relates to the technical field of environmental engineering, and in particular to a method and system for simulating unit lines of rainfall runoff on a green roof. Background Art

[0002] As one of the important components of urban green infrastructure (GI), green roof has attracted widespread attention because it can effectively alleviate the heat island effect, reduce building energy consumption, and reduce storm runoff. Green roof, also known as roof greening, is a new type of greening form that uses traditional urban impermeable roofs as carriers and plants as the main configuration. The structure from top to bottom is vegetation layer, matrix layer, filtration layer, (storage) drainage layer and waterproof layer, and the slope is generally less than 4%. Among them, the penetration and absorption of rainwater by the matrix layer is the main factor determining the rainwater storage capacity, and the vegetation layer consumes water through evaporation to maintain the rainwater penetration and absorption capacity of the matrix layer. In addition, plant stems and leaves also have a rainwater interception effect, which gradually increases with the increase of plant height, coverage and biomass.

[0003] A large number of studies have confirmed the effectiveness of green roofs in reducing rainfall runoff (including: total runoff, peak reduction, peak time delay, etc.), and many scholars have focused on the impact of green roof structural characteristics (including: vegetation type, substrate thickness, roof slope, operation time, etc.) on the differences in rainfall runoff reduction effects. Nowadays, the simulation of green roof rainfall runoff process is mainly based on the Richards equation describing soil water infiltration for numerical simulation. The relevant models include Hydrus-1D and SWMM-2D, which involve many parameters and complex solution processes, and it is difficult to intuitively reflect the response relationship between runoff results and rainfall conditions. In view of the complexity of the Richards equation, many scholars have proposed different simplified equations, but these equations all assume that the infiltration soil column is semi-infinite in length as the boundary condition, and mostly ignore the influence of the surface water change of the infiltration soil column, and mainly focus on the long-term infiltration process of soil water in the soil column. However, in fact, the thickness of the substrate soil layer used for rainwater infiltration on green roofs is limited. If the rainfall intensity is relatively small, the green roof will not generate runoff before the substrate soil layer of limited thickness reaches saturation. The process of seepage after the substrate soil layer reaches saturation and discharged through the drainage layer is the runoff process, and this runoff (seepage) process is more susceptible to changes in the surface rainfall (water accumulation) process of the substrate soil layer. Therefore, based on the limited thickness of the substrate soil layer of the green roof, combined with the simplified soil infiltration model, considering the impact of changes in the surface rainfall (water accumulation) process on the runoff (seepage to the drainage layer outflow) process, whether a simple and practical model reflecting the rainfall-runoff response relationship can be established has become a problem to be studied. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a method and system for simulating unit line of rainfall runoff on green roofs. By considering the specific physical properties of green roofs, rainfall characteristics and dynamic changes of soil water potential, a more accurate runoff simulation scheme is provided, which can effectively predict the runoff behavior of green roofs under different rainfall conditions, and provide theoretical support for the design of green roofs and urban hydrological management.

[0005] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0006] A method for simulating unit line of rainfall runoff on a green roof, comprising the following steps:

[0007] Step S1: obtaining the physical parameters of the green roof area, vertical structure, and soil type, thickness, and saturated hydraulic conductivity of the matrix soil layer;

[0008] Step S2: determining the maximum possible retention capacity of the green roof substrate soil layer before rainfall;

[0009] Step S3: real-time monitoring of rainfall runoff process;

[0010] Step S4: determining the generation time of rainfall runoff from the green roof;

[0011] Step S5: constructing the instantaneous unit line of green roof rainfall runoff;

[0012] Step S6: constructing a green roof rainfall runoff unit line model;

[0013] Step S7: Calculate the runoff result under a specific rainfall event according to the green roof rainfall runoff unit line model.

[0014] Furthermore, in step S1, the physical parameters of the green roof obtained include the green roof area, vertical structure, and soil type, thickness, and saturated hydraulic conductivity of the substrate soil layer, which are obtained by referring to relevant design instructions and hydrological soil technical manuals, or by on-site measurement and testing.

[0015] Furthermore, in step S2, the maximum possible retention capacity at that time is determined by determining the difference between the measured soil moisture content and the saturated moisture content, or estimating the maximum possible retention capacity at that time by referring to relevant technical engineering manuals.

[0016] Furthermore, in step S3, the real-time monitoring of rainfall runoff process is performed using a rain gauge and a "liquid level gauge + triangular weir" measurement method, and the triangular weir flow calculation is calculated using the following Kindsvater-Shen formula:

[0017]

[0018] Where: Q 堰 (t) is the outflow rate of the triangular weir; θ is the top angle of the triangular weir; C D is the flow coefficient; H e is the water head on the weir; g is the acceleration due to gravity.

[0019] Furthermore, in step S4, the determination of the flow generation time is based on comparing the relationship between the accumulated rainfall and the initial loss. When the two are equal, the flow generation time is set as follows:

[0020]

[0021] Where: t0 is the flow generation time; I(t) is the rainfall process; t is the time; I a is the initial loss; S is the maximum possible retention at that time; λ is the initial loss coefficient.

[0022] Furthermore, in step S5, when constructing the instantaneous unit line of rainfall runoff on the green roof, the influence of surface water depth on the infiltration rate after runoff generation is considered through the soil water saturation infiltration theory, and the capillary rise height at the wetting front and the air residual pressure term are ignored. The infiltration rate is expressed using Darcy's law, as shown in the following formula:

[0023]

[0024] Where: f p (t-t0) is the soil infiltration rate after runoff generation; Q(t-t0) is the outflow rate of the drainage layer, converted into runoff depth per unit time; h p (t-t0) is the surface water depth; l is the thickness of the matrix soil layer; H(t-t0) is the working water head; K s is the saturated hydraulic conductivity; t is the time; t0 is the saturated flow time;

[0025] For the acting water head H(t-t0), according to the principle of mass conservation, there is the following equilibrium equation:

[0026]

[0027] Where: I(t-t0) is the rainfall intensity after saturated runoff, Q(t-t0) is the outflow rate of the drainage layer, H(t-t0) is the action head, Indicates the rate of change of the applied head;

[0028] By solving the problem jointly, we can obtain the continuous convolution form of the runoff process after the green roof generates runoff:

[0029]

[0030] Among them, I(τ-t0) is the rainfall intensity, τ is the integral variable, and the expression of the instantaneous unit line u(0,t) is:

[0031]

[0032] Where: K d is the response rate parameter.

[0033] Furthermore, the response rate parameter K of the instantaneous unit line model is d The calculation expression is Where K s is the saturated hydraulic conductivity of the matrix soil layer, and l is the thickness of the matrix soil layer.

[0034] Furthermore, in step S6, the unit line model is based on the instantaneous unit line expression and is further converted into a discrete time period unit line form through S integral transformation:

[0035]

[0036] In the formula: q(Δt,n) is the unit line of the time period; Δt is the unit line time period; n is the time period number.

[0037] By combining the rainfall in different time periods with the unit line function of discrete time periods, a unit line model of the rainfall runoff process on the green roof is constructed:

[0038]

[0039] Where: I(i) is the rainfall intensity in different time periods; i0 is the sequence number of the start time period of runoff generation.

[0040] The present invention also discloses a green roof rainfall runoff unit line simulation system, which can be used to implement the above green roof rainfall runoff unit line simulation method, specifically including:

[0041] Physical parameter collection and analysis module: collects and analyzes the physical characteristic parameters of the green roof, including area, vertical structure, substrate soil type, soil layer thickness and its saturated hydraulic conductivity.

[0042] The module for calculating the maximum possible retention capacity at that time: according to the current moisture state of the green roof soil, the module calculates the maximum possible retention capacity of the substrate soil layer before rainfall.

[0043] Rainfall monitoring module: monitors the rainfall process in real time and records the intensity, duration and distribution of rainfall.

[0044] Runoff generation time determination module: Based on the characteristics of the rainfall process, calculate the time when the green roof generates runoff after the rainfall starts.

[0045] Unit line construction module: Based on the physical property parameters such as the thickness of the green roof matrix soil layer and the saturated hydraulic conductivity, the instantaneous unit line of rainfall runoff and the unit line of time period are constructed. The unit line is defined as the runoff response caused by unit precipitation.

[0046] Unit line model building module: The green roof rainfall process is convolved with the discrete time unit line to form a green roof rainfall runoff unit line model. This model can describe the response relationship of the runoff process under different rainfall processes.

[0047] Runoff calculation and result output module: Using the constructed unit line model and combining it with real-time rainfall data, the runoff response of the green roof under different rainfall events is calculated and output. The output results include: total runoff, flow process and peak flow.

[0048] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the green roof rainfall runoff unit line simulation method is implemented.

[0049] The present invention also discloses a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the green roof rainfall runoff unit line simulation method is implemented.

[0050] Compared with the prior art, the advantages of the present invention are:

[0051] 1. This paper constructs a more sophisticated and accurate green roof rainfall runoff unit line model by comprehensively considering multiple factors such as the physical parameters of the green roof, soil hydraulic characteristics, and dynamic changes in the rainfall process. Compared with traditional methods, it can more accurately reflect the rainfall runoff process of the green roof, especially the response changes under different rainfall intensities and durations.

[0052] 2. The method of the present invention can adjust the model parameters according to the physical properties of the green roof matrix soil layer, such as different types, thickness, saturated hydraulic conductivity, etc., so that it can adapt to runoff simulation under different types of soil and different climatic conditions. This makes the method of the present invention highly universal and adaptable, and suitable for the design and management of various green roof systems.

[0053] 3. By real-time monitoring of the green roof retention capacity, rainfall and runoff process, the rainfall runoff process simulation can be dynamically adjusted. This feature enables the present invention to evaluate the runoff response of different rainfall events in real time, and timely discover and solve possible drainage problems, which is of great significance for the management and optimization of green roofs.

[0054] 4. By accurately simulating the rainfall runoff characteristics of green roofs, the present invention provides a scientific basis for the design of green roofs. Designers can reasonably select parameters such as roof greening schemes, substrate thickness, soil types, etc. based on the simulation results to maximize the runoff control effect of green roofs and improve the energy efficiency and environmental comfort of buildings.

[0055] 5. The simulation method of the present invention provides an effective tool for urban rainwater management. Through the accurate prediction of rainfall runoff on green roofs, it can help urban planning departments to better manage rainwater and prevent floods and waterlogging, reduce environmental pollution and waterlogging problems caused by urban hardened surface runoff, and improve the sustainable development level of cities.

[0056] 6. Accurate rainfall runoff simulation helps improve the ability to evaluate the benefits of green roofs and enhance their environmental benefits in mitigating the urban heat island effect and improving rainwater utilization efficiency. By optimizing the rainfall management of green roofs, the utilization rate of rainwater can be effectively improved, the waste of urban water resources can be reduced, and the quality of the urban ecological environment can be improved.

[0057] 7. The method of the present invention is simple and easy to operate, and is compatible with the existing urban rainwater management system. Through the standardized simulation process, urban managers and designers can quickly apply the model of the present invention to calculate and analyze the rainfall runoff of green roofs, thereby promoting the popularization and application of green roofs. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of a method for simulating a unit line of rainfall runoff on a green roof according to an embodiment of the present invention.

[0059] Figure 2 The green roof layout structure and rainfall runoff monitoring diagram of the embodiment of the present invention; (a) is a plan layout diagram. (b) is a green roof structure diagram. (c) is a triangular weir flow channel device structure diagram.

[0060] Figure 3 1 and 10 are simulation results of the rainfall runoff process on a green roof according to an embodiment of the present invention; (a) is rainfall sequence 1, (b) is rainfall sequence 6, and (c) is rainfall sequence 10. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0062] Taking the monitoring and simulation of rainfall runoff on a green roof as an example, the specific implementation method of the unit line simulation method of rainfall runoff on a green roof of the present invention is further explained. The technical process is as follows: Figure 1 As shown, the following steps are included:

[0063] Step S1, obtaining the physical parameters of the green roof area, vertical structure, and soil type, thickness, and saturated hydraulic conductivity of the matrix soil layer;

[0064] The green roof area, vertical structure, and soil type and thickness of the matrix soil layer can be determined by referring to relevant design instructions, hydrological soil technical manuals, or on-site measurements. The saturated hydraulic conductivity of the green roof matrix soil layer can be determined by referring to relevant hydrological soil technical manuals or experiments.

[0065] In this embodiment, the green roof is located in a water science and technology research institute in a certain city. By consulting relevant design instructions and on-site measurements, the green roof greening ratio is 100% and the area is about 65m 2 (See Figure 2 a), the vertical structure is as follows (see Figure 2 b): (1) The grass species of the vegetation layer is selected from Sedum, which has the characteristics of drought resistance, water saving, heat insulation and cooling, and easy management; (2) The matrix layer uses a mixture of peat soil, vermiculite and sand, with a thickness of 6 cm and a ratio of 4:2:1. It has the characteristics of light weight, good water permeability, good water retention, stable performance and easy maintenance; (3) The filter layer is located at the bottom of the matrix layer. The material is filter cloth (thickness 1-2 cm) to prevent medium loss; (4) The drainage layer is 5 cm thick and made of lightweight plastic. The bowl-shaped structure is evenly arranged to carry the runoff and has a drainage outlet. Through experimental measurement and consulting relevant hydrological soil technical manuals, it is determined that the saturated hydraulic conductivity of the green roof matrix layer soil is about 12 mm / min. The large value may be related to the mixed sand in the matrix layer soil.

[0066] Step S2, determining the maximum possible retention of the green roof substrate soil layer before rainfall;

[0067] The maximum possible retention capacity of the green roof matrix layer soil before rainfall can be determined by the difference between the measured soil moisture content and the saturated moisture content, or by consulting relevant technical engineering manuals and reasonably selecting dimensionless runoff curve numbers to estimate the maximum possible retention capacity at that time. The conversion relationship between the two is:

[0068]

[0069] Where: S is the maximum possible retention at that time, mm; CN is called the runoff curve number, which is affected by factors such as soil type, previous humidity, vegetation conditions, slope and land use. The theoretical value range is 0 to 100, and the actual range is 40 to 98.

[0070] The main steps for determining the value of the runoff curve number CN include:

[0071] Step S21, classifying the hydrological groups (divided into four categories: A, B, C, and D) according to the soil infiltration or runoff generation capacity;

[0072] Step S22, combining land use type, vegetation cover and hydrological conditions (divided into three categories: good, medium and poor), etc., and referring to relevant technical engineering manuals to select CN values;

[0073] Step S23, considering the influence of the previous soil moisture level AMC, introducing the previous precipitation index API (at least the cumulative rainfall in the previous 5 days), and converting and taking values ​​according to the classification (divided into AMC level I / drought, AMC level II / normal and AMC level III / humid);

[0074] Step S24, taking the influence of the slope into consideration, and performing slope correction on the CN value.

[0075] In this embodiment, through experimental measurement and combined with reference to relevant technical engineering manuals, the parameters such as the maximum possible retention, initial loss and initial loss coefficient of the green roof matrix soil layer at different rainfall events are determined as shown in Table 1. Among them, the initial loss at different rainfall events is basically linearly related to the maximum possible retention at that time, and the average value of the initial loss coefficient is about 0.26.

[0076] Table 1 Statistics of parameters such as the maximum possible retention volume, initial loss and runoff coefficient of the green roof

[0077]

[0078] Step S3, real-time monitoring of rainfall runoff process;

[0079] Rain gauges can be used to monitor the rainfall process on green roofs, and their performance meets the requirements of relevant specifications. For monitoring the runoff process of green roof rainfall, the "liquid level meter + triangular weir" measurement method can be used to continuously monitor the water level and flow. The triangular weir flow calculation is different before and after overflow. The roof runoff in the calculation period before overflow is the product of the water level difference at the beginning and end of the period and the bottom area of ​​the weir. The Kindsvater-Shen formula is used to calculate the flow through the weir after overflow:

[0080]

[0081] Where: Q 堰 (t) is the outflow rate of the triangular weir, m 3 / s; θ is the top angle of the triangular weir, which is 30°; C D is the flow coefficient, which is 0.6; H e is the water head on the weir, m; g is the acceleration due to gravity, m / s 2 .

[0082] In this embodiment, the rainfall process monitoring is mainly carried out by installing a rain gauge on the roof, which can obtain the 1-minute and 5-minute rainfall values ​​and obtain the daily meteorological data of a certain weather station, including rainfall, temperature (maximum and minimum), relative humidity, sunshine, wind speed, etc. The runoff process monitoring adopts the "liquid level meter + triangular weir" measurement method to continuously monitor the water level and flow. A triangular weir flow measuring trough device is installed under the outlet of the roof drain pipe (see Figure 2 c) A liquid level gauge is installed in the tank. The GlobalWater WL-16 pressure level gauge is used. The storage capacity is 81759 records. It is powered by two 9V lithium batteries. The measurement accuracy is ±0.1% full scale under constant temperature conditions. The top angle of the triangular weir is 30° and the bottom area is 0.4m 2 .

[0083] Step S4, determining the generation time of rainfall runoff on the green roof;

[0084] According to the maximum possible retention of soil in the green roof matrix layer before rainfall, the initial loss is estimated based on the linear assumption. The relationship between the two is:

[0085] I a =λS (3)

[0086] Where: I a is the initial loss, mm; λ is the initial loss coefficient, which mainly depends on geographical and climatic factors and ranges from 0.1 to 0.3.

[0087] In this embodiment, according to the statistical parameters such as the maximum possible retention, initial loss and initial loss coefficient of the green roof matrix soil layer at different rainfall events in Table 1, combined with the rainfall process monitoring in step S3, the cumulative rainfall and the initial loss are compared. When the two are equal, it is the runoff generation time;

[0088] Step S5, constructing an instantaneous unit line of rainfall runoff on the green roof;

[0089] According to the theory of soil water saturation infiltration, the combined forces acting on the infiltration soil column include: surface area water depth, infiltration soil column length, capillary rise height at the wetting front, and air residual pressure. Assuming that the thickness of the green roof matrix soil layer is l, after the matrix soil layer is saturated and produces runoff, the influence of surface area water depth is mainly considered, and the capillary rise height at the wetting front and air residual pressure terms are ignored. Then the infiltration rate can be expressed as formula (4) according to Darcy's law, and is converted into runoff through the drainage layer:

[0090]

[0091] Where: f p(t-t0) is the soil infiltration rate after runoff generation, mm / min; Q(t-t0) is the outflow rate of the drainage layer, converted into runoff depth per unit time, mm / min; h p (t-t0) is the surface water depth, mm; l is the thickness of the matrix soil layer, mm; H(t-t0) is the water head, mm; K s is the saturated hydraulic conductivity, mm / min; t is the time, min; t0 is the saturated flow time, min.

[0092] For the acting water head H(t-t0), according to the principle of mass conservation, there is the following equilibrium equation:

[0093]

[0094] Where: I(t-t0) is the rainfall intensity after saturated runoff, mm / min.

[0095] By jointly solving equations (4) and (5), we can obtain the continuous convolution form of the runoff process after the green roof generates runoff:

[0096]

[0097] The expression of the instantaneous unit line u(0,t) is:

[0098]

[0099] Where: K d is the response rate parameter, which is the inverse of the steady infiltration time of the matrix soil layer (the thickness of the matrix soil layer divided by the saturated hydraulic conductivity), min -1 .

[0100] For the response rate parameter K d , the calculation expression is as follows:

[0101]

[0102] Step S6, constructing a green roof rainfall runoff unit line model.

[0103] Based on the instantaneous unit line formula (7), it is further converted into the discrete time unit line form through S integral transformation:

[0104]

[0105] In the formula: q(Δt,n) is the unit line of the time period; Δt is the unit line time period; n is the time period number.

[0106] By combining the rainfall in different time periods with the unit line function of discrete time periods, a unit line model of the rainfall runoff process on the green roof is constructed:

[0107]

[0108] Where: I(i) is the rainfall intensity in different time periods, mm / min; i0 is the sequence number of the start of runoff generation.

[0109] Step S7: Calculate the runoff result under a specific rainfall event according to the green roof rainfall runoff unit line model.

[0110] In this embodiment, taking rainfall sequences 1, 6, and 10 as examples, Figure 3 The simulation results of the rainfall runoff process of the green roof are shown in Figure 1. The vertical axis value in the figure is converted into rainfall and runoff depth in the period based on formula (10) by multiplying both sides by Δt (5min).

[0111] Select the coefficient of certainty R 2 and Nash-Sutcliffe efficiency coefficient E NS As an evaluation index of the model effect. Among them, the coefficient of certainty R 2 It is the most basic quantitative analysis method for evaluating the model effect. Excel software can be used to perform linear regression between the flow calculation value and the measured value. 2 The closer the value is to 1, the better the flow simulation value fits the measured value; Nash-Sutcliffe efficiency coefficient E NS It is a standardized statistical value to determine the relative amount of variance between the residual and the measured data. NS The value is generally between -∞ and 1. NS =1 indicates that the calculated flow value is completely consistent with the measured value. <E NS When NSE is less than 1, it indicates that the calculation effect is within an acceptable level. When NSE is less than 0, it indicates that there is a large deviation between the calculated flow value and the measured value. NS The efficiency coefficient calculation expression is:

[0112]

[0113] Where: E NS is the Nash-Sutcliffe efficiency coefficient; Q o i is the measured flow rate, mm / min; Q c i is the flow simulation value, mm / min.

[0114] from Figure 3 It can be seen that the calculated value of the green roof rainfall runoff process is consistent with the measured value, and the certainty coefficient R 2 With E NS The efficiency coefficient values ​​reach 0.84 and 0.85 respectively, and the simulation effect is good.

[0115] In another embodiment of the present invention, a green roof rainfall runoff unit line simulation system is provided. The system can be used to implement the above green roof rainfall runoff unit line simulation method, specifically including:

[0116] Physical parameter collection and analysis module: collects and analyzes the physical characteristic parameters of the green roof, including area, vertical structure, substrate soil type, soil layer thickness and its saturated hydraulic conductivity.

[0117] The module for calculating the maximum possible retention capacity at that time: according to the current moisture state of the green roof soil, the module calculates the maximum possible retention capacity of the substrate soil layer before rainfall.

[0118] Rainfall monitoring module: monitors the rainfall process in real time and records the intensity, duration and distribution of rainfall.

[0119] Runoff generation time determination module: Based on the characteristics of the rainfall process, calculate the time when the green roof generates runoff after the rainfall starts.

[0120] Unit line construction module: Based on the physical property parameters such as the thickness of the green roof matrix soil layer and the saturated hydraulic conductivity, the instantaneous unit line of rainfall runoff and the unit line of time period are constructed. The unit line is defined as the runoff response caused by unit precipitation.

[0121] Unit line model building module: The green roof rainfall process is convolved with the discrete time unit line to form a green roof rainfall runoff unit line model. This model can describe the response relationship of the runoff process under different rainfall processes.

[0122] Runoff calculation and result output module: Using the constructed unit line model and combining it with real-time rainfall data, the runoff response of the green roof under different rainfall events is calculated and output. The output results include: total runoff, flow process and peak flow, etc.

[0123] In another embodiment of the present invention, a terminal device is provided, the terminal device includes a processor and a memory, the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, which are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions to implement the corresponding method flow or corresponding functions; the processor described in the embodiment of the present invention can be used for the operation of the green roof rainfall runoff unit line simulation method.

[0124] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It is understandable that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and the extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory, or a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0125] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the green roof rainfall runoff unit line simulation method in the above embodiment; one or more instructions in the computer-readable storage medium are loaded and executed by the processor.

[0126] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0127] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0128] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0129] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0130] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the implementation methods of the present invention, and should be understood that the protection scope of the present invention is not limited to such special statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for simulating unit line of rainfall runoff on a green roof, characterized in that: The following steps are involved: Step S1: obtaining the physical parameters of the green roof area, vertical structure, and soil type, thickness, and saturated hydraulic conductivity of the matrix soil layer; Step S2: determining the maximum possible retention capacity of the green roof substrate soil layer before rainfall; Step S3: real-time monitoring of rainfall runoff process; Step S4: determining the generation time of rainfall runoff from the green roof; Step S5: constructing the instantaneous unit line of green roof rainfall runoff; Step S6: constructing a green roof rainfall runoff unit line model; Step S7: Calculate the runoff result under a specific rainfall event according to the green roof rainfall runoff unit line model.

2. The green roof rainfall runoff unit line simulation method according to claim 1 is characterized by: In step S1, the physical parameters of the green roof obtained include the soil type, thickness, and saturated hydraulic conductivity of the green roof matrix soil layer, which are obtained by referring to relevant design instructions or hydrological soil technical manuals, or by on-site measurements.

3. The green roof rainfall runoff unit line simulation method according to claim 1 is characterized by: In step S2, the maximum possible retention capacity at that time is determined by determining the difference between the measured soil moisture content and the saturated moisture content, or estimating the maximum possible retention capacity at that time by referring to relevant technical engineering manuals.

4. The green roof rainfall runoff unit line simulation method according to claim 1 is characterized by: In step S3, the real-time monitoring of rainfall runoff process is carried out by using a rain gauge and a "liquid level meter + triangular weir" measurement method, and the triangular weir flow calculation is calculated by the following Kindsvater-Shen formula: Where: Q 堰 (t) is the outflow rate of the triangular weir; θ is the top angle of the triangular weir; C D is the flow coefficient; H e is the water head on the weir; g is the acceleration due to gravity.

5. The green roof rainfall runoff unit line simulation method according to claim 1 is characterized by: In step S4, the determination of the flow generation time is based on the comparison of the relationship between the accumulated rainfall and the initial loss. When the two are equal, the flow generation time is set as follows: Where: t0 is the flow generation time; I(t) is the rainfall process; t is the time; I a is the initial loss; S is the maximum possible retention at that time; λ is the initial loss coefficient.

6. The green roof rainfall runoff unit line simulation method according to claim 1, characterized in that: In step S5, when constructing the instantaneous unit line of rainfall runoff on the green roof, the influence of surface water depth on the infiltration rate after runoff generation is considered through the soil water saturation infiltration theory, and the capillary rise height at the wetting front and the air residual pressure term are ignored. The infiltration rate is expressed by Darcy's law, which is as follows: Where: f p (t-t0) is the soil infiltration rate after runoff generation; Q(t-t0) is the outflow rate of the drainage layer, converted into runoff depth per unit time; h p (t-t0) is the surface water depth; l is the thickness of the matrix soil layer; H(t-t0) is the working water head; K s is the saturated hydraulic conductivity; t is the time; t0 is the saturated flow time; For the acting water head H(t-t0), according to the principle of mass conservation, there is the following equilibrium equation: Where: I(t-t0) is the rainfall intensity after saturated runoff, Q(t-t0) is the outflow rate of the drainage layer, H(t-t0) is the action head, Indicates the rate of change of the applied head; By solving the problem jointly, we can obtain the continuous convolution form of the runoff process after the green roof generates runoff: Among them, I(τ-t0) is the rainfall intensity, τ is the integral variable, and the expression of the instantaneous unit line u(0,t) is: Where: K d is the response rate parameter.

7. The instantaneous unit line of rainfall runoff on a green roof according to claim 6, characterized in that: The response rate parameter K of the unit line model d The calculation expression is Where K s is the saturated hydraulic conductivity of the matrix soil layer, and l is the thickness of the matrix soil layer.

8. The green roof rainfall runoff unit line simulation method according to claim 1, characterized in that: In step S6, the unit line model is based on the instantaneous unit line expression and is further converted into a discrete time unit line form through S integral transformation: In the formula: q(Δt,n) is the time period unit line; Δt is the unit line time period; n is the time period sequence number; By combining the rainfall in different time periods with the unit line function of discrete time periods, a unit line model of the rainfall runoff process on the green roof is constructed: Where: I(i) is the rainfall intensity in different time periods; i0 is the sequence number of the start time period of runoff generation.

9. A green roof rainfall runoff unit line simulation system, characterized by: The system can be used to implement the green roof rainfall runoff unit line simulation method according to any one of claims 1 to 8, specifically comprising: Physical parameter collection and analysis module: collects and analyzes the physical characteristic parameters of the green roof, including area, vertical structure, substrate soil type, soil layer thickness and its saturated hydraulic conductivity; The module for calculating the maximum possible retention volume at that time: according to the current moisture state of the green roof soil, the module calculates the maximum possible retention volume of the matrix soil layer before rainfall; Rainfall monitoring module: real-time monitoring of rainfall process, recording rainfall intensity, duration and distribution; Module for determining the runoff generation time: based on the characteristics of the rainfall process, it calculates the time when the green roof generates runoff after the rainfall starts; Unit line construction module: Based on the physical property parameters such as the thickness of the green roof matrix soil layer and the saturated hydraulic conductivity, the instantaneous unit line of rainfall runoff and the unit line of time period are constructed; the unit line is defined as the runoff response caused by unit precipitation; Unit line model building module: convolute the green roof rainfall process with the discrete time unit line to form a green roof rainfall runoff unit line model; this model can describe the response relationship of the runoff process under different rainfall processes; Runoff calculation and result output module: Utilize the constructed unit line model and combine with real-time rainfall data to calculate and output the runoff response of the green roof under different rainfall events; the output results include: total runoff, flow process and peak flow.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the green roof rainfall runoff unit line simulation method described in one of claims 1 to 8 is implemented.

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