A method and system for evaluating dual functions of ditches and ponds in agricultural areas based on reference system

Abstract

The present invention discloses a dual function evaluation method of ditches and ponds in agricultural areas based on a reference system, including investigation of the current status system of ditches and ponds; establishment of a reference system based on the current status system of ditches and ponds; construction of the topological structure of the distributed current status system of ditches and ponds and the reference system; acquisition of characteristic parameters describing the current status system of ditches and ponds and the reference system; according to the characteristic parameters of the current status system of ditches and ponds and the reference system, a set of indicators based on the reference system is proposed to describe the dual functions of farmland drainage and environmental services of ditches and ponds; based on the proposed indicators, the dual functions of the current status system of ditches and ponds and the reference system are evaluated respectively. The present invention is to balance and coordinate the contradictory relationship between the drainage and environmental service functions of the ditches and ponds system. The proposed method is a way to simplify indicators and strive for rules, which can be relatively easily integrated into the hydrological and water quality model of rivers or lakes; the method is based on the landform of ditches and ponds and can provide technical references for the migration and prevention of pollutants.

Description

Technical Field

[0001] The invention relates to the technical field of water environment management, in particular to a method and system for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system. Background Art

[0002] The connectivity and layout optimization of water systems in agricultural areas are an important part of the current improvement of the rural ecological environment and the construction of beautiful villages in my country. The plain river network area in southern my country is rich in water resources, and the dense ditch and pond river network is the most unique landform landscape in the water town. While providing drainage channels for agricultural production, the ditch and pond system also plays the ecological service function of wetlands, and is an important place to reduce agricultural non-point source pollutants. Therefore, the ditch and pond system in agricultural areas has the dual functions of farmland drainage and environmental services, but due to different mechanisms of action, there is a certain contradiction between the two functions, and the improvement of one function will have a certain negative impact on the other.

[0003] As the drainage system continues to improve, the area required for the ditch and pond system has been greatly reduced. From the perspective of agricultural production, the reduction of the ditch and pond system has increased the area of ​​production land and improved drainage efficiency; however, from the perspective of environmental function, this change has shortened the retention time of drainage in the ditch and pond system, reduced the ability to remove pollutants, and weakened the environmental function of the ditch and pond. In the past, most of the research on the ditch and pond system focused on its environmental function or drainage function, but there was less research on the relationship between its dual functions. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] The present invention is proposed in view of the problems existing in the relationship between the dual functions of the above-mentioned ditch and pond system.

[0006] Therefore, the problem to be solved by the present invention is how to balance the impact of changes in the ditch and pond system on the rise and fall of its dual functions.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In the first aspect, an embodiment of the present invention provides a method for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system, which includes collecting data on the current status system of ditches and ponds; establishing a reference system based on the current status system of ditches and ponds; constructing a topological structure of a distributed current status system of ditches and ponds and a reference system; obtaining characteristic parameters describing the current status system of ditches and ponds and the reference system; proposing indicators based on the reference system based on the characteristic parameters of the current status system of ditches and ponds and the reference system; and performing dual function evaluations on the current status system of ditches and ponds and the reference system based on the proposed indicators.

[0009] As a preferred scheme of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system described in the present invention, the reference system is based on three principles for constructing the layout of the ditch and pond reference system, and establishes the most effective layout scheme to maintain the current drainage needs under the constraints of natural conditions.

[0010] As a preferred scheme of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system described in the present invention, the three principles based on the construction of the layout of the ditch and pond reference system include straightening, that is, arranging the curved drainage ditches in the ditch and pond system to be straight; eliminating redundancy, that is, eliminating the hydraulic redundancy in the ditch and pond system; hydrological connectivity, that is, adding drainage ditches between farmland with high drainage pressure and unconnected drainage units to increase the hydrological connectivity of the ditch and pond system.

[0011] As a preferred scheme of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system described in the present invention, wherein: constructing the topological structure of the distributed ditch and pond status system and the reference system includes determining the relative position and hydraulic connection of each element in the ditch and pond system, abstracting the ditch and pond components into points, lines and surfaces, and performing ditch and pond flow network analysis and drainage classification on the ditch and pond system; obtaining characteristic parameters describing the ditch and pond status system and the reference system includes performing data processing and analysis based on preliminary survey data and the constructed topological structure to obtain characteristic parameters describing the ditch and pond status system and the reference system.

[0012] As a preferred solution of the dual function evaluation method of agricultural ditches and ponds based on the reference system of the present invention, the index based on the reference system includes defining the drainage efficiency index ε relative to the reference system. h , the specific formula is as follows:

[0013]

[0014] Among them, E h E is the characteristic parameter that characterizes the drainage function of the current system. h,r To characterize the characteristic parameters of the drainage function of the reference system, the calculation process is as follows:

[0015]

[0016]

[0017] Where i is the unit sequence, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter k i and k i,r are the stage numbers of the i-th drainage unit in the current system and the reference system, N and N r are the total number of ditch and pond units for the current system and the reference system, respectively.

[0018] As a preferred solution of the dual function evaluation method of agricultural ditches and ponds based on the reference system of the present invention, the index based on the reference system also includes defining the environmental efficiency index ε relative to the reference system. e , the specific formula is:

[0019]

[0020] Among them, E e E is the characteristic parameter that characterizes the environmental function of the current system. e,r To characterize the characteristic parameters of the reference system environmental function, the calculation process is as follows:

[0021]

[0022]

[0023] Among them, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter Q i and Q i,r are the flow rates of the i-th drainage ditch and pond unit in the current system and the reference system, N and N r are the total number of ditch and pond units for the current system and the reference system, respectively.

[0024] As a preferred solution of the dual function evaluation method of agricultural ditches and ponds based on the reference system described in the present invention, the dual function evaluation of the current ditch and pond system and the reference system includes the following steps: based on the dual function index, the drainage function and environmental function of the current ditch and pond system and the reference system are calculated respectively, so as to quantify the dual functions of the current ditch and pond system and the reference system; combining the composition characteristics of the ditch and pond system and the calculation results of the dual function efficiency, the drainage and environmental dual functions of the current ditch and pond system are compared and analyzed; wherein the comparative analysis of the dual functions of the current ditch and pond system includes the following rules: when there are large ponds and large ditches in the drainage system, there is ε h <1 and ε e >1; in the process of gradually improving the efficiency of the drainage system, it will lead to ε hGradually increase, ε e Gradually decrease, and eventually both values ​​tend to 1; when the drainage system is insufficient and the system layout needs to be increased in the future, ε h and ε h The evolution law is just the opposite.

[0025] In the second aspect, an embodiment of the present invention provides a dual-function evaluation system for ditches and ponds in agricultural areas based on a reference system, which includes a ditch and pond status system survey module, which is used for the status survey of the ditch and pond system; a reference system establishment module, which is used to establish a reference system that maintains the most effective layout of the current drainage demand under natural conditions; a topology structure construction module, which is used to construct the topology structure of the distributed ditch and pond status system and the reference system; a data acquisition module, which is used to obtain characteristic parameters describing the ditch and pond status system and the reference system; an indicator construction module, which is used to propose a set of indicators based on the reference system to describe the dual functions of farmland drainage and environmental services of ditches and ponds; and a dual-function evaluation module, which is used to perform dual-function evaluation of the ditch and pond status system and the reference system respectively according to the proposed indicators.

[0026] In a third aspect, an embodiment of the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the method for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system as described in the first aspect of the present invention are implemented.

[0027] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the method for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system as described in the first aspect of the present invention are implemented.

[0028] The beneficial effects of the present invention are as follows: traditional ditch and pond evaluation methods mainly focus on single aspects such as drainage function or ecological environmental benefits, and it is difficult to evaluate the comprehensive benefits of ditches and ponds; by comprehensively considering the dual functions of drainage and environment of the ditch and pond system in the southern plain river network area, combined with certain dynamic characteristic analysis, the evaluation method proposed by the present invention can comprehensively consider the relationship and contradiction between ditch and pond drainage and environmental functions, so as to more comprehensively evaluate the ditch and pond functions; in addition, the present invention can also evaluate the dual functions of ditches and ponds under different future adjustment scenarios, so as to derive the impact mechanism of ditch and pond water system changes on their dual functions; the evaluation method proposed by the present invention has important reference significance for coping with future ditch and pond system water system changes, rationally planning agricultural water system connectivity and layout optimization, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0030] Figure 1 This is the overall flow chart of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system in Example 1.

[0031] Figure 2 This is a schematic diagram of the reference system establishment process of the dual function evaluation method of agricultural ditches and ponds based on the reference system in Example 1.

[0032] Figure 3 This is the drainage ditch and pond distribution and drainage direction map of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system in Example 2.

[0033] Figure 4 This is the reference system ditch and pond distribution and drainage direction map of Example 2 based on the reference system of the dual function evaluation method of ditches and ponds in agricultural areas.

[0034] Figure 5 This is the drainage ditch and pond flow network analysis and drainage classification diagram of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system of Example 2.

[0035] Figure 6 This is the reference system ditch and pond flow network analysis and drainage classification diagram of the dual function evaluation method of ditches and ponds in agricultural areas based on the reference system in Example 2. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0039] Example 1

[0040] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, and provides a method for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system, comprising:

[0041] S1: Collect information about the current status of ditches and ponds.

[0042] Specifically, ditch and pond data are obtained based on a systematic survey of their current status, including the use of field surveys, satellite map analysis, and drone remote sensing technologies to survey the water depth, area, hydraulic connections, and existing natural conditions of the ditch and pond system.

[0043] It should be noted that methods for obtaining survey and analysis data include but are not limited to actual surveys, historical data compilation, satellite image analysis, and drone remote sensing monitoring.

[0044] It should be noted that when investigating the existing ditch and pond system, it is necessary to determine the restrictions on the ditch and pond system imposed by farmland and terrain (for example, due to local practical reasons, the outflow outlet of the existing ditch and pond system is limited to a certain outlet. At this time, part of the drainage water from the farmland may not be able to flow out from high to low along the slope of the farmland. This is a limitation of the ditch and pond system).

[0045] S2: Establish a reference system based on the existing ditch and pond system.

[0046] Preferably, since the primary function of the drainage ditch and pond system is to provide drainage services for farmland, its distribution characteristics are inherent attributes and are gradually improved in the long-term development of agricultural production. Therefore, from the perspective of drainage efficiency and convenience of agricultural production, if the ditch and pond system has a large area (ditch or pond) and too many drainage levels, it means that the system drainage efficiency is "low" and there is a certain hydraulic redundancy, that is, it is not necessary in terms of drainage function, but its environmental function is enhanced due to the larger distribution area. Therefore, a drainage ditch and pond system that operates efficiently in distribution can be considered as a constraint condition for the minimum requirements of environmental functions. A reference system is specially defined as the most effective layout to maintain the current drainage needs under the constraints of natural conditions.

[0047] Furthermore, a reference system based on the existing system of ditches and ponds is established, including the three principles for constructing the layout of the ditch and pond reference system, establishing the most effective layout that maintains the existing drainage needs under the constraints of natural conditions, and adjusting the layout of the existing ditches and ponds according to the three principles (the principle of straightening, the principle of eliminating redundancy, and the principle of hydrological connectivity) to eliminate hydraulic redundancy in the original system, such as units (ditches and ponds) that are not needed hydraulically (drainage), reducing drainage classification, and using straight drainage ditches to replace the original curved ditches.

[0048] Specifically, the three principles include the principle of straightening the curved ditches, which is to arrange the curved drainage ditches in the ditch and pond system to be straight; the principle of eliminating redundancy, which is to eliminate the hydraulic redundancy in the ditch and pond system, such as removing hydraulically unnecessary (drainage) units (ditches, ponds, drainage ditches, etc.) and reducing the width of hydraulically redundant drainage ditches; the principle of hydrological connectivity, which is to add drainage ditches between farmland with high drainage pressure and unconnected drainage units to increase the hydrological connectivity of the ditch and pond system.

[0049] Preferably, the reference system is established according to the three principles of establishing a reference system, wherein Figure 2 The following is a schematic diagram of the reference system establishment process. The reference system is established for the real system A: 1. Eliminate redundancy: remove the ditches and ponds with hydraulic redundancy; 2. Straighten the ditches: change the three curved agricultural ditches into straight ones; 3. Hydrological connectivity: after removing the ditches and ponds, the water system is not connected, and the length of the agricultural ditches on both sides is extended to maintain the connectivity of the water system.

[0050] Further, by Figure 2 The schematic diagram of the reference system establishment process shows that compared with the 5 drainage units and 4 drainage levels of the actual system A, the reference system B has fewer drainage units (4) and levels (3 levels). This shows that after the reference system is established in the ditches and ponds, hydraulic redundancy is eliminated and the drainage efficiency of the system is improved.

[0051] S3: Construct the topological structure of the distributed ditch and pond status system and the reference system.

[0052] Furthermore, the drainage ditches, ponds and other components in the ditch-pond system are abstracted into individual points, lines and surfaces, and the relative position, hydraulic connection and water source of each node are clarified.

[0053] It should be noted that the hydraulic connection between each node specifically refers to the upstream and downstream order of water flow between each node. The water source of each node includes but is not limited to upstream water and direct drainage from farmland.

[0054] Furthermore, the topological structure of the distributed ditch and pond status system and the reference system is constructed based on the above information. Specifically, the flow network analysis and drainage classification diagram are drawn.

[0055] It should be noted that the plain river network area in southern my country has low terrain, poor regional drainage, and complex water system connectivity, making it difficult to accurately simulate hydrological and water quality models. Against this background, constructing the topological structure of the ditch-pond system can weaken the specific form of the ditch-pond system, emphasize the topological structure characteristics and hydraulic connection of the ditch-pond system, and then better evaluate the drainage and environmental functions of the ditch-pond system.

[0056] S4: Obtain characteristic parameters describing the current system of ditches and ponds and the reference system.

[0057] Furthermore, based on the preliminary survey data and the constructed topological structure, data processing and analysis were performed to obtain characteristic parameters that can describe the current system and reference system of ditches and ponds.

[0058] Specifically, based on the construction of topological structure, the flow network analysis and drainage classification of the ditch and pond system were carried out to obtain the dynamic parameter drainage stage k. Data analysis was carried out based on the current situation of the ditch and pond system: remote sensing images were downloaded, and the land in the study area was classified using geographic information system analysis software to obtain the static parameters of the ditch and pond system unit, the ditch and pond area A, and the farmland area A' acting on the ditch and pond unit. The dynamic parameter drainage flow Q includes the flow from the upstream and the farmland drainage flow Q'. The specific formula is as follows:

[0059] Q i =Q i-1 +Q' i

[0060] Q' i =A'q0

[0061] Among them, i is the unit sequence (the value range is 0 to N, N is the total number of ditch and pond units), Q i is the drainage flow of the i-th ditch and pond unit, Q i-1 is the drainage flow of the i-1th ditch and pond unit, Q i ' is the farmland drainage flow of the i-th ditch and pond unit, and q0 is the average drainage flux of the farmland (taking the local observation value).

[0062] S5: Based on the characteristic parameters of the current system and the reference system of ditches and ponds, a set of indicators based on the reference system are proposed to describe the dual functions of ditches and ponds in farmland drainage and environmental services.

[0063] Specifically, the following steps are included:

[0064] S5.1: Based on certain dynamic characteristics (for example, the dynamic characteristics of the ditch-pond system are mainly the dynamics of water flow. When dynamic parameters are added to the indicators describing the dual functions of the ditch-pond system, such as drainage flow Q, this indicator can reflect the dynamic characteristics of the ditch-pond system to a certain extent), an indicator that can reflect the dual functions of the ditch-pond system is proposed.

[0065] S5.2: Define the drainage efficiency index ε relative to a reference system. h , the specific formula is as follows:

[0066]

[0067] Among them, E h E is the characteristic parameter that characterizes the drainage function of the current system. h,r To characterize the characteristic parameters of the drainage function of the reference system, the calculation process is as follows:

[0068]

[0069]

[0070] Where i is the unit sequence, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter k i and k i,r are the stage numbers of the i-th drainage unit in the current system and the reference system, N and N r are the total number of ditch and pond units for the current system and the reference system, respectively.

[0071] S5.3: Define the environmental efficiency index ε relative to a reference system e , the specific formula is:

[0072]

[0073] Among them, E e E is the characteristic parameter that characterizes the environmental function of the current system. e,r To characterize the characteristic parameters of the reference system environmental function, the calculation process is as follows:

[0074]

[0075]

[0076] Among them, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter Q i and Q i,r are the flow rates of the i-th drainage ditch and pond unit in the current system and the reference system, N and N r are the total number of ditch and pond units for the current system and the reference system, respectively.

[0077] It should be noted that the efficiency in the present invention is defined based on the reference system. When evaluating the actual system, the efficiency value may be greater than 1, where the reference system efficiency value is 1. The closer the efficiency value is to 1, the closer its efficiency is to the efficiency of the reference system.

[0078] It should be noted that the efficiency index represents the characteristic parameters of the current drainage and environment (E h and E e ) and the reference system (E h,r and E e,r ) compared to E h and E e They are contradictory (one increases and the other decreases), so a certain value of the current situation will be larger than the corresponding value of the reference system, that is, the efficiency index will be greater than 1.

[0079] S6: Based on the proposed indicators, dual functional evaluation of the current ditch and pond system and the reference system is carried out respectively.

[0080] Furthermore, based on the dual function index, the drainage function and environmental function of the current ditch and pond system and the reference system are calculated respectively, so as to quantify the dual functions of the current ditch and pond system and the reference system.

[0081] Furthermore, combining the composition characteristics of the ditch-pond system and the calculation results of the dual-function efficiency, a comparative analysis of the dual functions of drainage and environment of the current ditch-pond system was conducted.

[0082] Preferably, by combining the composition characteristics of the ditch-pond system and the calculation results of the dual-function efficiency, there are some rules when comparing and analyzing the dual functions of the current ditch-pond system, including that when there are large ponds and large ditches in the drainage system, there is ε h <1 and ε e >1, that is, the hydraulic efficiency is lower than the reference system, while the environmental efficiency is higher than the reference system; in the process of gradually improving the efficiency of the drainage system, it will lead to ε h Gradually increase, ε e gradually decreases, and eventually both values ​​tend to 1; in the case where the drainage system is insufficient and the system layout needs to be increased in the future, ε h and ε h The evolution law is just the opposite.

[0083] Furthermore, the present embodiment also provides a dual-function evaluation system for ditches and ponds in agricultural areas based on a reference system, including a ditch and pond status system survey module, which is used for the status survey of the ditch and pond system; a reference system establishment module, which is used to establish a reference system that maintains the most effective layout of the current drainage demand under natural conditions; a topology structure construction module, which is used to construct the topology structure of the distributed ditch and pond status system and the reference system; a data acquisition module, which is used to obtain characteristic parameters describing the ditch and pond status system and the reference system; an indicator construction module, which is used to propose a set of indicators based on the reference system to describe the dual functions of farmland drainage and environmental services of ditches and ponds; and a dual-function evaluation module, which is used to conduct dual-function evaluations of the ditch and pond status system and the reference system respectively according to the proposed indicators.

[0084] This embodiment also provides a computer device, which is applicable to the dual-function evaluation method of ditches and ponds in agricultural areas, and includes a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement the dual-function evaluation method of ditches and ponds in agricultural areas as proposed in the above embodiment.

[0085] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0086] This embodiment also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the following steps: survey of the current status system of ditches and ponds; establishment of a reference system based on the current status system of ditches and ponds; construction of a topological structure of a distributed current status system of ditches and ponds and a reference system to obtain characteristic parameters describing the current status system of ditches and ponds and the reference system; based on the characteristic parameters of the current status system of ditches and ponds and the reference system, a set of indicators based on the reference system are proposed to describe the dual functions of farmland drainage and environmental services of ditches and ponds; and based on the proposed indicators, dual function evaluations of the current status system of ditches and ponds and the reference system are respectively performed.

[0087] In summary, the present invention comprehensively considers the dual functions of drainage and environment of ditch and pond systems in agricultural areas in the southern plain river network area. On the basis of certain dynamic characteristics, it comprehensively considers the relationship and contradiction between ditch and pond drainage and environmental functions. This method has a certain self-consistency and can provide a quantitative analysis tool for the current status evaluation and future development planning of the ditch and pond system in the plain river network area.

[0088] Example 2

[0089] Reference Figure 3 to Figure 6 , which is the second embodiment of the present invention, provides a dual-function evaluation method for ditches and ponds in agricultural areas based on a reference system. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0090] Specifically, the farmland drainage ditch pond located in the Yangzhou Farmland Water Conservancy Scientific Research Station Experimental Base in Jiangdu District, Yangzhou City, Jiangsu Province was selected as a case study. Figure 3 This is a map of drainage ditch and pond distribution and drainage direction.

[0091] Further, in Figure 3 Based on the three principles of reference system layout, the most effective layout to maintain the current drainage demand under natural conditions is established. Figure 4 The ditch and pond reference system shown.

[0092] It should be noted that from Figure 4 It can be seen that after the entire ditch and pond drainage system was reconnected and rezoned, the drainage channels became more regular and uniform, redundant units were removed, and areas where the original drainage layout was incomplete were added.

[0093] Specifically, the changes include: transforming two ponds into branch ditches (one as an extension of the existing branch ditch), and reducing the branch ditch width from the current 8m to 3m, removing the two redundant branch ditches on the upper left, adding an agricultural ditch unit at the bottom, and connecting the two smaller independent drainage areas at the bottom to form one branch. The final reference system includes 6 reduced branch ditches (8m width reduced to 3m) and 10 agricultural ditches. These changes have reduced the ditch and pond area by 57% and the drainage classification from 6 to 5.

[0094] Furthermore, on this basis, two ditch and pond system reconstruction models were developed according to the layout of the reference system and the future development trend of the ditch and pond system.

[0095] The preferred mode 1 (layout optimization) does not reduce the size of the branch ditch, which can be regarded as a solution with relatively small changes to the existing ditch and pond drainage system, and the ditch and pond area is only reduced by 16.4%.

[0096] The preferred mode 2 (reference system + concealed pipes replacing farm ditches) takes into account future mechanized operations and land saving requirements, and adopts drainage concealed pipes to replace farm ditches, which will lead to a 68.8% reduction in the area of ​​existing ditches and ponds (excluding concealed pipes).

[0097] Furthermore, the comparison of the existing system, reference system and ditch-pond system schemes under different transformation modes shows that the widely distributed and large-area tributaries have the greatest impact on the area composition as shown in Table 1 (composition characteristics of the ditch-pond system and reference system in the study area under different situations).

[0098] Table 1 Composition characteristics of the ditch-pond system and reference system in the study area under different conditions

[0099]

[0100] Furthermore, the topological structure analysis of the current ditch and pond system, reference system and transformation model abstracts the components such as drainage ditches and ponds in the ditch and pond system into individual points, lines and surfaces, and clarifies the relative position, hydraulic connection and water source of each node.

[0101] It should be noted that the hydraulic connection between each node specifically refers to the upstream and downstream order of water flow between each node. The water source of each node includes but is not limited to upstream water and direct drainage from farmland.

[0102] Furthermore, the topological structure of the distributed ditch and pond system is constructed based on the above information. Specifically, the distribution of ditch and pond and the drainage direction are first drawn based on the field survey and remote sensing image analysis; then the flow network analysis and drainage classification are carried out according to the hydraulic connection between the drainage units of the ditch and pond system; the topological structure of the current system and the reference system of the distributed ditch and pond is constructed. Figure 3 to Figure 6 .

[0103] It should be noted that the plain river network area in southern my country is low-lying, with poor regional drainage and complex water system connectivity, making it difficult to accurately simulate hydrological and water quality models. In this context, constructing the topological structure of the ditch-pond system can weaken the specific form of the ditch-pond system, emphasize the topological structure characteristics and hydraulic connection of the ditch-pond system, and then better evaluate the drainage and environmental functions of the ditch-pond system.

[0104] Furthermore, parameters describing the characteristics of the ditch-pond system were obtained based on the current status and the established reference system and two transformation modes.

[0105] Furthermore, based on the construction of topological structure, the flow network analysis and drainage classification of the ditch and pond system were carried out to obtain the dynamic parameter drainage stage k. Data analysis was carried out based on the current situation of the ditch and pond system: remote sensing images were downloaded, and the land in the study area was classified using geographic information system analysis software to obtain the static parameters of the ditch and pond system unit, the ditch and pond area A, and the farmland area A' acting on the ditch and pond unit. The dynamic parameter drainage flow Q includes the flow from the upstream and the farmland drainage flow Q'. The specific formula is as follows:

[0106] Q i =Q i-1 +Q' i

[0107] Q' i =A'q0

[0108] Among them, i is the unit sequence (the value range is 0 to N, N is the total number of ditch and pond units), Q i is the drainage flow of the i-th ditch and pond unit, Q i-1 is the drainage flow of the i-1th ditch and pond unit, Q i ' is the farmland drainage flow of the i-th ditch and pond unit, and q0 is the average drainage flux of the farmland (taking the local observation value).

[0109] Furthermore, based on the proposed dual-function evaluation method of ditches and ponds in agricultural areas based on the reference system, the dual functions of the existing ditch and pond system, the reference system and the two transformation models were evaluated, and the drainage function efficiency and environmental function efficiency of the existing ditch and pond system and the two transformation models were evaluated compared with the reference system.

[0110] Furthermore, the drainage efficiency coefficient and environmental efficiency coefficient of the ditch-pond system under different scenarios were calculated. It can be seen from Table 1 and Table 2 (calculation results) that, relative to the reference system (values ​​are all 1), the area ratios of the current situation, mode 1 (layout optimization) and mode 2 (reference system + concealed agricultural ditch) are 2.33, 1.94 and 0.72, respectively. The drainage efficiency coefficient gradually increases from 0.40 in the current situation to 0.44 in mode 1 and 1.25 in mode 2, while the environmental efficiency coefficient decreases from 2.92 to 2.40 in mode 1 and 0.81 in mode 2.

[0111] It should be noted that in the case of Mode 2, assuming that the drainage ditch is replaced by a concealed pipe, its drainage efficiency (1.25) is higher than that of the reference system, while its environmental efficiency coefficient (0.81) is lower than that of the reference system.

[0112] Table 2 Drainage and environmental coefficients of ditch-pond systems under different scenarios

[0113]

[0114] Furthermore, the largest branch ditch in the current study area occupies 60% of the total area. Adjusting it will have the greatest impact on the entire system. The reference system is to reduce the current oversized branch ditch from 8m to 3m, resulting in a 57% reduction in the overall ditch area. It can be seen from Table 2 that the corresponding drainage efficiency coefficient increased by 150% (0.4 to 1.0), while the environmental efficiency decreased by 66% (2.92 to 1.0).

[0115] Specifically, it can be seen from Tables 1 and 2 that from the current situation to Mode 1, it only involves transforming the pond into a branch ditch, while the size of the branch ditch remains unchanged, the total area of ​​the ditch and pond is only reduced by 16%, the drainage efficiency coefficient is only increased by 10% (0.40 to 0.44), and the environmental efficiency is reduced by 18% (2.92 to 2.40); from the reference system to Mode 2, assuming that 10 of the 16 ditch units are replaced by concealed pipes, this will lead to a 28% reduction in area, an increase in the drainage coefficient by 25% (1 to 1.25), and a decrease in environmental efficiency by 19% (1 to 0.81).

[0116] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for evaluating the dual functions of ditches and ponds in agricultural areas based on a reference system, characterized by: include, Collect the current status of ditches and ponds; Establish a reference system based on the existing system of ditches and ponds; Construct the topological structure of the distributed ditch and pond status system and reference system; Obtain characteristic parameters describing the current system and reference system of ditches and ponds; According to the characteristic parameters of the current ditch and pond system and the reference system, the index based on the reference system is proposed; Based on the proposed indicators, dual functional evaluations of the current ditch and pond system and the reference system were conducted; The reference system is based on three principles for constructing the layout of the ditch and pond reference system, establishing the most effective layout plan to maintain the current drainage demand under the constraints of natural conditions; The three principles for constructing the ditch and pond reference system layout include: The principle of straightening the curved drainage ditch is to arrange the curved drainage ditch in the ditch-pond system to be straight; Eliminate redundancy principle, that is, eliminate hydraulic redundancy in the ditch-pond system; The principle of hydrological connectivity, that is, adding drainage ditches between farmlands with high drainage pressure and disconnected drainage units to increase the hydrological connectivity of the ditch-pond system; The topological structure of the distributed ditch and pond status system and the reference system includes determining the relative position and hydraulic connection of each element in the ditch and pond system, abstracting the ditch and pond components into points, lines and surfaces, and performing ditch and pond flow network analysis and drainage classification on the ditch and pond system; The obtaining of characteristic parameters describing the current status system of the ditch and pond and the reference system includes performing data processing and analysis based on the previous survey data and the constructed topological structure to obtain characteristic parameters describing the current status system of the ditch and pond and the reference system; The indicators based on the reference system include: Define the drainage efficiency index ε relative to the reference system h , the specific formula is as follows: Among them, E h E is the characteristic parameter that characterizes the drainage function of the current system. h,r To characterize the characteristic parameters of the drainage function of the reference system, the calculation process is as follows: Where i is the unit sequence, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter k i and k i,r are the stage numbers of the i-th drainage unit in the current system and the reference system, N and N r are the total number of ditch and pond units in the current system and the reference system, respectively; The indicators of the reference system also include: Define the environmental efficiency index ε relative to the reference system e , the specific formula is: Among them, E e E is the characteristic parameter that characterizes the environmental function of the current system. e,r To characterize the characteristic parameters of the reference system environmental function, the calculation process is as follows: Among them, the static parameter A i and A i,r are the areas of the i-th drainage ditch and pond unit in the current system and the reference system, respectively, and the dynamic parameter Q i and Q i,r are the flow rates of the i-th drainage ditch and pond unit in the current system and the reference system, N and N r are the total number of ditch and pond units in the current system and the reference system, respectively; The dual function evaluation of the current system and the reference system includes the following steps: Based on the dual function index, the drainage function and environmental function of the current ditch and pond system and the reference system are calculated respectively, so as to quantify the dual functions of the current ditch and pond system and the reference system. Combined with the composition characteristics of the ditch-pond system and the calculation results of the dual-function efficiency, the dual functions of drainage and environment of the current ditch-pond system are compared and analyzed; The dual functions of the comparative analysis of the current status of the ditch and pond system include the following rules: In the case of a large pond and a large ditch in the drainage system, there is ε h <1 and ε e >1; In the process of gradually improving the efficiency of the drainage system, it will lead to ε h Gradually increase, ε e Gradually decrease, and eventually both values ​​tend to 1; In the case that the drainage system is insufficient and the system layout needs to be increased in the future, ε h and ε h The evolution law is just the opposite.

2. A dual function evaluation system for agricultural ditches and ponds based on a reference system, based on the dual function evaluation method for agricultural ditches and ponds based on a reference system according to claim 1, characterized in that: Also includes, The ditch and pond status system survey module is used for the current status survey of the ditch and pond system; A reference system building module is used to build a reference system that maintains the most effective layout of the current drainage requirements under natural conditions; Topology building module, used to build the topology of the distributed ditch and pond status system and reference system; A data acquisition module is used to obtain characteristic parameters describing the current system of the ditch and pond and the reference system; An indicator building block for proposing a set of indicators based on a reference system to describe the dual functions of farmland drainage and environmental services of ditches and ponds; The dual function evaluation module is used to carry out dual function evaluation of the current ditch and pond system and the reference system according to the proposed indicators.

3. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to claim 1 are implemented.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to claim 1 are implemented.

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