Irrigation area rotation irrigation grouping optimization method considering water delivery time

Abstract

The invention provides an irrigation area rotation irrigation grouping optimization method considering water delivery time, which comprises the following steps of: firstly, calculating water delivery time of water flow of a superior channel from a channel head to each water diversion channel; then, taking the minimum difference between the water delivery time of each water diversion channel and the water diversion starting time as one of objective functions, and establishing an irrigation area rotation irrigation grouping optimization function considering the water delivery time; and solving the rotation irrigation grouping optimization function by using an NSGA-II algorithm to obtain an optimized rotation irrigation grouping scheme. The irrigation area rotation irrigation grouping scheme made according to the method is more suitable for the actual situation, and a theoretical reference is provided for scientific and reasonable allocation and full and reasonable utilization of water resources in an irrigation area.

Description

Technical Field

[0001] The present invention relates to a rotation irrigation method for crop irrigation areas, and in particular to an irrigation area rotation irrigation grouping optimization method taking water delivery time into consideration. The present invention belongs to the technical field of efficient utilization and management of water resources in crop irrigation areas. Background Art

[0002] my country is a large agricultural country, and agricultural water consumption accounts for more than 60% of the total national water consumption, most of which is used for irrigation. In the field of crop irrigation, water distribution management of irrigation canals plays a vital role in the efficient use of water resources and the stable development of agricultural production. With the increasing scarcity of water resources and the advancement of agricultural modernization, how to reasonably optimize the water distribution plan of irrigation canals has become a key issue that needs to be solved urgently and has important practical significance.

[0003] At present, the canal system in my country's irrigation area is generally composed of a multi-level canal system of trunk, branch, bucket and agricultural canals. For bucket and agricultural canal systems, due to the limitation of the water delivery capacity of the upper canal, the group rotation irrigation method is generally used for irrigation. The traditional group rotation irrigation method mostly relies on the irrigation area management experience to determine the water distribution flow and water distribution time of each channel. Its advantages are simple operation and easy implementation, and it can solve the water distribution problem of the irrigation area to a certain extent. However, with the increasingly prominent contradiction between the supply and demand of agricultural water resources, this traditional rotation irrigation method is difficult to meet higher water distribution requirements, and often has problems such as long irrigation water delivery and distribution time, serious waste of water resources, and untimely water supply caused by small flow water distribution. Focusing on such problems, many scholars and experts have conducted a lot of research on this and proposed a rotation irrigation grouping method based on a variety of optimization algorithms (such as genetic algorithm, particle swarm algorithm, ant colony algorithm). Since water distribution in irrigation canals is a relatively complex process, existing rotation irrigation grouping algorithms often focus on the optimal matching and combination between crop water demand and channel water delivery capacity, with the goal of minimizing irrigation water delivery time, and determine the start and end time of water distribution for each water distribution channel, while ignoring the time lag factor of water flow in the water delivery process. In actual irrigation projects, it takes a certain amount of time for water to be transported from upstream to downstream, and the water delivery characteristics of different channels vary greatly, including factors such as channel length, roughness, and cross-sectional shape that also affect the water delivery speed. If this is not taken into account, it will be difficult for the water distribution plan to achieve the expected effect. For example, when the water distribution channel starts to distribute water, the water from the upper channel has not reached the water distribution channel. It is necessary to wait for the water flow to arrive before normal water distribution can be achieved, resulting in a longer irrigation time for the entire rotation period and affecting the water supply service level of the irrigation area. Summary of the invention

[0004] In view of the above reasons, the purpose of the present invention is to provide an optimization method for irrigation area rotation grouping taking into account the water delivery time. The method fully considers the water delivery time of the water flow from the upper channel to each water diversion channel from the head of the channel, formulates the water distribution plan for each irrigation area rotation grouping, realizes the scientific and reasonable allocation of water resources in the irrigation area, and ensures the sustainable development of agricultural production.

[0005] To achieve the above purpose, the present invention adopts the following technical scheme: an irrigation area rotation group optimization method considering water delivery time, firstly, calculating the water delivery time of the water flow from the head of the upper channel to each water diversion channel; then, taking the minimum difference between the water delivery time of each water diversion channel and its start water diversion time as one of the objective functions, establishing the irrigation area rotation group optimization function considering the water delivery time; using the NSGA-Ⅱ algorithm to solve the rotation group optimization function, and obtaining the optimized rotation group scheme;

[0006] Specific methods:

[0007] Step 1: Collect basic data, including:

[0008] Design flow Q of the upper channel d , unit m 3 / s, cross-sectional information of the upper channel;

[0009] The distance L between each diversion channel and the headwaters i , unit m, design flow rate q of each water diversion channel d,i , unit m 3 / s, water demand of each water diversion channel w i , unit m 3 ;

[0010] Step 2: Calculate the water transfer time S from the head of the upper channel to each diversion channel i ,

[0011]

[0012] In the formula, S i is the water delivery time of the ith water diversion channel, in seconds; V is the water volume of the upper channel at the final state of flow change, in m 3 ; Q is the water flow rate of the upper channel, unit is m 3 / s;L i is the distance from the i-th diversion channel to the head of the channel, in m; c is the water velocity of the upper channel, in m / s; g is the acceleration of gravity; A is the cross-sectional area of ​​the upper channel, in m 2 ; B is the water surface width of the upper channel, in m; v is the average flow velocity of the upper channel, in m / s; n is the roughness coefficient of the upper channel; i is the bottom slope of the upper channel; R is the hydraulic radius of the upper channel, in m;

[0013] Step 3: Establish an optimization function for irrigation area rotation grouping taking into account water delivery time;

[0014] S3.1. Set decision variables: t s,i is the water distribution start time of the ith water diversion channel, in seconds;

[0015] S3.2. Establish the objective function:

[0016] Objective function 1: The irrigation cycle T of this round is the shortest;

[0017] The present invention uses the maximum value of the water distribution end time of all water distribution channels to represent the current irrigation cycle T;

[0018] minT=max(t e，i )

[0019]

[0020] Where, t e,i is the water distribution end time of the ith water diversion channel, in seconds; t s,i is the water distribution start time of the ith water diversion channel, in seconds; w i is the water demand of the ith water diversion channel, in m 3 ;q d,i is the design flow of the ith diversion channel, in m 3 / s;

[0021] Objective function 2: The difference between the start time of water distribution in the water diversion channel and the water delivery time from the headwaters to the water diversion channel is minimized;

[0022] minP=∑Δt

[0023]

[0024] S3.3. Set constraints: The sum of the flow rates of the diversion channels that distribute water simultaneously should be between 0.6 and 1 times the design flow rate of the upper channel:

[0025] Constraint: 0.6Q d ≤Σq d,i ≤Q d

[0026] In the formula, Q d Design traffic for upstream channels;

[0027] Step 4: The optimization function of irrigation area rotation grouping considering water delivery time established in step 3 is solved by genetic algorithm using the geatpy toolbox, including:

[0028] Initialization: Set the encoding format, create a decoding matrix through the crtfld() function, and use the Population() function to instantiate the population object;

[0029] Select algorithm template: call moea_NSGA2_templet() function to implement multi-objective optimization NSGA-Ⅱ algorithm;

[0030] Parameter setting: set the maximum number of evolutionary generations and crossover probability;

[0031] Optimization calculation: Call the run() function to execute the algorithm template to obtain the Pareto optimal solution set NDSet and the most optimal generation population.

[0032] Preferably, the maximum evolutionary generation is set to 1000; and the crossover probability is set to 0.7. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the irrigation area rotation grouping optimization method considering the water delivery time of the present invention;

[0034] Figure 2 A schematic diagram of channel distribution according to an embodiment of the present invention;

[0035] Figure 3 for Figure 2 The canal system shown is a time chart of water distribution according to the traditional method of rotation irrigation;

[0036] Figure 4 for Figure 2 The canal system shown is a rotation irrigation and water distribution time diagram according to the method provided by the present invention. DETAILED DESCRIPTION

[0037] The structure and features of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that various modifications can be made to the embodiments disclosed herein, and therefore, the embodiments disclosed in the specification should not be regarded as limiting the present invention, but are merely examples of embodiments, the purpose of which is to make the features of the present invention obvious.

[0038] In actual irrigation projects, due to the differences in length, cross-sectional shape, and surface roughness of the upper channel, it takes a certain amount of time for the water in the upper channel to be transported from the upstream to the downstream. If this is not taken into consideration, the water distribution time point of the lower channel / water diversion channel may have arrived, but the water in the upper channel has not yet reached the water diversion channel, affecting irrigation and causing the entire rotation period to be extended. Therefore, when formulating the irrigation area rotation group water distribution plan, the present invention fully considers the water transfer time from the upper channel to the lower channel, so that the formulated irrigation rotation group water distribution plan is more scientific and reasonable, and the water resource utilization rate is high.

[0039] The present invention provides an irrigation area rotation group optimization method considering water delivery time. First, the water delivery time of the water flow from the head of the upper channel to each water diversion channel is calculated; then, the difference between the water delivery time of each water diversion channel and its start water diversion time is minimized as one of the objective functions, and the irrigation area rotation group optimization function considering the water delivery time is established; finally, the NSGA-Ⅱ algorithm is used to solve the rotation group optimization function to obtain an optimized rotation group scheme. Figure 1 As shown, the specific implementation method is:

[0040] Step 1: Collect basic data, including:

[0041] 1. Design flow Q of the upper channel d (m 3 / s), cross-sectional information of the upper channel;

[0042] 2. The distance L between each diversion channel and the headwaters i (m), the design flow rate of each water diversion channel q d,i (m 3 / s), water demand of each water diversion channel w i (m 3 ).

[0043] Step 2: Calculate the water transfer time S from the head of the upper channel to each diversion channel i ,

[0044]

[0045] In the formula, S i is the water delivery time of the ith water diversion channel (in seconds); V is the water volume of the upper channel at the final state of flow change (m 3 ); Q is the water flow rate of the upper channel (m 3 / s), Li is the distance from the i-th diversion channel to the head of the channel (m), c is the water velocity of the upper channel (m / s), g is the gravity acceleration, and A is the cross-sectional area of ​​the upper channel (m 2 ), B is the water surface width of the upper channel (m), v is the average flow velocity of the upper channel (m / s), n is the roughness coefficient of the upper channel, i is the bottom slope of the upper channel, and R is the hydraulic radius of the upper channel (m).

[0046] Step 3: Establish an optimization function for irrigation area rotation grouping taking into account water delivery time.

[0047] S3.1. Set decision variables: t s,i is the water distribution start time of the i-th water diversion channel (s).

[0048] S3.2. Establish the objective function:

[0049] Objective function 1: The irrigation cycle T of this round is the shortest.

[0050] The present invention uses the maximum value of the water distribution end time of all water distribution channels to represent the current irrigation cycle T.

[0051] minT=max(t e，i )

[0052]

[0053] Where, t e,i is the water distribution end time of the ith water diversion channel (s); t s,i is the water distribution start time of the ith water diversion channel (s); w i is the water demand of the ith water diversion channel (m 3 );q d,i is the design flow of the ith diversion channel.

[0054] Objective function 2: The difference between the start time of water distribution in the water diversion channel and the water delivery time from the headwaters to the water diversion channel is minimized;

[0055] minP=∑Δt

[0056]

[0057] S3.3. Set constraints: The sum of the flow rates of the diversion channels that distribute water simultaneously should be between 0.6 and 1 times the design flow rate of the upper channel:

[0058] Constraint: 0.6Q d ≤∑q d,i ≤Q d

[0059] In the formula, Q d Design traffic for upstream channels.

[0060] Step 4: The optimization function of irrigation area rotation grouping considering water delivery time established in step 3 is solved by genetic algorithm using the geatpy toolbox, including:

[0061] Initialization: Set the encoding format, create a decoding matrix through the crtfld() function, and use the Population() function to instantiate the population object;

[0062] Select algorithm template: call moea_NSGA2_templet() function to implement multi-objective optimization NSGA-Ⅱ algorithm;

[0063] Parameter setting: Set the maximum number of evolution generations and crossover probability.

[0064] The maximum evolutionary number is set according to the complexity of the problem. In a preferred embodiment of the present invention, the maximum evolutionary number is set to 1000. The crossover probability is set according to the problem type. In a preferred embodiment of the present invention, the crossover probability is set to 0.7.

[0065] Optimization calculation: Call the run() function to execute the algorithm template to obtain the Pareto optimal solution set NDSet and the most optimal generation population.

[0066] The irrigation area rotation group optimization method considering the water delivery time of the present invention is applied to a water distribution in a certain irrigation area in Xinjiang, and the advantages of the present invention are verified by comparing the water distribution results of the following three rotation irrigation methods: rotation irrigation method 1, the traditional "top-down" water distribution method, rotation irrigation method 2, the rotation irrigation group optimization method without considering the water delivery time, and rotation irrigation method 3, the rotation irrigation group optimization method considering the water delivery time of the present invention.

[0067] Step 1: Collect basic data

[0068] 1. Design flow Q of the upper channel d 1.5m 3 / s, channel longitudinal slope is 0.0016, channel roughness is 0.017, channel section is trapezoidal, bottom width is 1m, and section slope is 1.5.

[0069] 2. Distribution of canal systems Figure 2 As shown, there are 19 water diversion channels, numbered 1-19.

[0070] 3. The distance L between each diversion channel and the headwaters i , the design flow rate of each water diversion channel q d,i , water demand of each water diversion channel w i As shown in Table 1, the total water demand of the 19 diversion channels is 132,800 m 3 .

[0071] Table 1 Basic information of water diversion channels

[0072] Channel Number <![CDATA[L i (m)]]> <![CDATA[q d,i (m 3 / s)]]> <![CDATA[w i (m 3 )]]> 1 1490 0.90 21500 2 2790 0.68 10300 3 4991 0.62 13800 4 6920 0.28 5300 5 7500 0.22 6100 6 9608 0.50 10100 7 11279 0.30 5600 8 11800 0.34 5500 9 11954 0.14 3000 10 13209 0.30 6900 11 14505 0.20 3500 12 15188 0.18 3200 13 16617 0.18 2200 14 18250 0.22 5100 15 19198 1.18 20700 16 19657 0.18 2200 17 20491 0.14 3000 18 22080 0.30 2900 19 23275 0.18 1900

[0073] Step 2: Calculate the water transfer time S from the head of the upper channel to each diversion channel i .

[0074] According to the calculation formula of water delivery time, the flow rate of the upper channel changes from 0 to 1.5m 3 / s, the water transfer time S of the upper channel from the headwater to each diversion channel i , as shown in Table 2 below.

[0075] Table 2 Water delivery schedule for each water diversion channel

[0076]

[0077]

[0078] Step 3: Establish an optimization function for irrigation area rotation grouping taking into account water delivery time.

[0079] Step 4: For the irrigation area rotation grouping optimization function considering the water delivery time established in step 3, the geatpy toolbox is used to implement the genetic algorithm solution.

[0080] The water distribution results of the three rotation irrigation methods are shown in Table 3.

[0081] Method 1: Traditional "top-down" water distribution method, design flow Q in the upper channel d Within the range (Q d 1.5m 3 / s), and water is distributed in the order of water distribution channels. No channel will be skipped during the irrigation process. Under this water distribution method, this round of irrigation is divided into 6 irrigation groups, as shown in Table 3 and Figure 3 As shown in the figure, water diversion channel No. 1 is group 1, water diversion channels No. 2 and No. 3 are group 2; water diversion channels No. 4, No. 5, No. 6 and No. 7 are group 3, water diversion channels No. 8-13 are group 4, water diversion channels No. 14 and No. 15 are group 5, and water diversion channels No. 16-19 are group 6. If water distribution starts at 0 o'clock, the end time is 141484s (39.3h). Since the water flow from the upper channel from the head to the water diversion channel No. 1 of the first round of irrigation group takes 1944s, in actual operation, water distribution starts at 1944s for water diversion channel No. 1, and the actual end time of irrigation for all water diversion channels is 143428s (39.8h).

[0082] Method 2: The rotation irrigation grouping method without considering the water delivery time. The optimization function of this method only includes objective function 1, that is, the shortest irrigation cycle T of this round, and the water distribution plan is formulated with the minimum irrigation end time as the goal. Under this water distribution method, the 19 water diversion channels are divided into 5 rotation irrigation groups, as shown in Table 3. The No. 1, No. 5, No. 14 and No. 17 water diversion channels are the first irrigation group, the No. 2, No. 6, No. 11 water diversion channels are the second irrigation group, the No. 3, No. 9, No. 10, No. 13 and No. 19 water diversion channels are the third irrigation group, the No. 4, No. 7, No. 8, No. 12 and No. 18 water diversion channels are the fourth irrigation group, and the No. 15 and No. 16 water diversion channels are the fifth irrigation group. If water distribution starts at 0 o'clock, the end time is 107397s (29.8h). Since the water delivery time from the head of the upper channel to the No. 17 water diversion channel of the first irrigation group is 26733s, in actual operation, the channel starts distributing water at 26733s, and the actual end time of the rotation irrigation of all water diversion channels is 134130s (37.3h).

[0083] Method 3: According to the rotation irrigation group optimization method considering the water delivery time of the present invention, a water distribution plan is formulated with the goal of minimizing the irrigation end time and minimizing the difference between the water distribution start time of the water distribution channel and the water delivery time of the channel water flow from the headwater to the water distribution channel. Under this water distribution method, this round of irrigation is divided into 5 rotation irrigation groups, as shown in Table 3 and Figure 4 As shown in the figure, No. 1, No. 4 and No. 5 water diversion channels are the first irrigation group, No. 2, No. 8 and No. 16 water diversion channels are the second irrigation group, No. 3, No. 9, No. 10, No. 14 and No. 19 water diversion channels are the third irrigation group, No. 6, No. 7, No. 11, No. 12, No. 13 and No. 17 water diversion channels are the fourth irrigation group, and No. 15 and No. 18 water diversion channels are the fifth irrigation group. If water distribution starts at 0 o'clock, the end time is 106054s (29.5h). Since the water delivery time from the upper channel to the No. 5 water diversion channel of the first irrigation group from the head of the channel is 9785s, in actual operation, the channel starts to distribute water from 9785s, and the actual end time of all water diversion channels after the irrigation is completed is 115839s (32.2h).

[0084] In summary, the completion time of rotation irrigation of all water distribution channels of the three rotation irrigation methods is 39.8h, 37.3h and 32.2h respectively. It can be seen that the rotation irrigation group water distribution completion time of the present invention is the shortest and the best.

[0085] Table 3 Water distribution results of different methods

[0086]

[0087] The present invention uses hydraulic formulas to calculate the water delivery time from the head of the canal to each water diversion channel. On this basis, the difference between the start time of water distribution in the water diversion channel and the water delivery time of the channel water flow to the water diversion channel is minimized as one of the optimization goals, rather than a constraint condition, to formulate a rotation irrigation grouping plan that comprehensively considers the water delivery time and irrigation duration.

[0088] The irrigation area rotation grouping scheme formulated according to the present invention is more in line with the actual situation, and provides a theoretical reference for realizing the scientific and reasonable allocation of water resources in the irrigation area and the full and reasonable utilization of water resources.

[0089] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing irrigation rotation grouping in irrigation areas considering water delivery time, characterized in that: Firstly, the water delivery time from the head of the upper channel to each water diversion channel is calculated; then, the difference between the water delivery time of each water diversion channel and its water diversion start time is minimized as one of the objective functions, and the irrigation area rotation grouping optimization function considering the water delivery time is established; the NSGA-Ⅱ algorithm is used to solve the rotation grouping optimization function, and the optimized rotation grouping scheme is obtained; Specific methods: Step 1: Collect basic data, including: Design flow Q of the upper channel d , unit m 3 / s, cross-sectional information of the upper channel; The distance L between each diversion channel and the headwaters i , unit m, design flow rate q of each water diversion channel d,i , unit m 3 / s, water demand of each water diversion channel w i , unit m 3 ; Step 2: Calculate the water transfer time S from the head of the upper channel to each diversion channel i , In the formula, S i is the water delivery time of the ith water diversion channel, in seconds; V is the volume of water in the upper channel at the final state of flow change, in m 3 ; Q is the water flow rate of the upper channel, unit is m 3 / s;L i is the distance from the i-th diversion channel to the head of the channel, in m; c is the water velocity of the upper channel, in m / s; g is the acceleration of gravity; A is the cross-sectional area of ​​the upper channel, in m 2 ; B is the water surface width of the upper channel, unit: m; v is the average flow velocity of the upper channel, in m / s; n is the roughness coefficient of the upper channel; i is the bottom slope of the upper channel; R is the hydraulic radius of the upper channel, in m; Step 3: Establish an optimization function for irrigation area rotation grouping taking into account water delivery time; S3.

1. Set decision variables: t s,i is the water distribution start time of the ith water diversion channel, in seconds; S3.

2. Establish the objective function: Objective function 1: The irrigation cycle T of this round is the shortest; minT=max(t e，i ) Where, t e，i is the water distribution end time of the ith water diversion channel, in seconds; t s，i is the water distribution start time of the ith water diversion channel, in seconds; w i is the water demand of the ith water diversion channel, in m 3 ;q d,i is the design flow of the ith diversion channel, in m 3 / s; Objective function 2: The difference between the start time of water distribution in the water diversion channel and the water delivery time from the headwaters to the water diversion channel is minimized; minP=∑Δt S3.

3. Set constraints: The sum of the flow rates of the diversion channels that distribute water simultaneously should be between 0.6 and 1 times the design flow rate of the upper channel: Constraint: 0.6Q d ≤∑q d，i ≤Q d In the formula, Q d Design traffic for upstream channels; Step 4: The optimization function of irrigation area rotation grouping considering water delivery time established in step 3 is solved by genetic algorithm using the geatpy toolbox, including: Initialization: Set the encoding format, create a decoding matrix through the crtfld() function, and use the Population() function to instantiate the population object; Select algorithm template: call moea_NSGA2_templet() function to implement multi-objective optimization NSGA-II algorithm; Parameter setting: set the maximum number of evolutionary generations and crossover probability; Optimization calculation: Call the run() function to execute the algorithm template to obtain the Pareto optimal solution set NDSet and the most optimal generation population.

2. The irrigation area rotation grouping optimization method considering water delivery time according to claim 1 is characterized by: The maximum number of evolution generations is set to 1000; The crossover probability is set to 0.7.

Images