Design method of structural parameters of rainwater collection root zone supplemental irrigation device

Abstract

The application provides a design method of structural parameters of a rainwater collection root zone supplemental irrigation device, which simultaneously considers a rainwater collection surface area, a water storage tank volume and a ceramic emitter design flow rate, establishes a rainwater collection and utilization behavior calculation formula in the device at a daily scale, and according to the formula, combines with local daily rainfall data, soil water holding capacity and nursery root zone range, and takes the highest operation guarantee rate of the rainwater collection micro-porous ceramic root zone supplemental irrigation device in the arid region as the target to design the structural parameters including the rainwater collection surface area, the water storage tank volume and the ceramic emitter rated flow rate. The application first proposes the design method of the structural parameters of the rainwater collection micro-porous ceramic root zone supplemental irrigation device, which is helpful to improve the rainwater utilization efficiency of the rainwater collection root zone supplemental irrigation of the nursery seedling in the arid region, and further helps to improve the nursery achievement rate and the preservation rate in the afforestation project in the arid region.

Description

Technical Field

[0001] The invention belongs to the technical field of water-saving irrigation in arid forestry, relates to parameter design of a rain-collecting root zone supplementary irrigation device, and particularly relates to a design method for structural parameters of a rain-collecting root zone supplementary irrigation device. Background Art

[0002] Arid regions, comprising approximately 41% of the world's total land surface area, are a vital component of Earth's terrestrial ecosystem, supporting over 38% of the world's population. Afforestation is commonly used to improve the ecological environment in these regions. However, due to water scarcity and insufficient per capita water availability, ensuring the survival of trees in these regions remains a major challenge for afforestation projects.

[0003] To improve the ecological environment in arid areas, afforestation is often adopted. Although rainwater harvesting and irrigation technologies, including pit irrigation, deep infiltration rainwater collection, and micro-irrigation, have achieved certain development and application, they still suffer from low rainwater utilization efficiency and high equipment investment costs. For example, pit irrigation exposes the soil, resulting in high water evaporation and prone to surface runoff during rainfall, which cannot meet the soil moisture needs of seedlings. Deep infiltration rainwater collection uses mulch as a rainwater collection material, which is easily broken during afforestation projects, resulting in reduced rainwater collection efficiency. Micro-irrigation rainwater collection requires the artificial construction of intercepting ditches or confluence channels and the excavation of water cellars or reservoirs, resulting in high investment costs and operating and management expenses. Summary of the Invention

[0004] In view of the defects and shortcomings of the existing technology, the purpose of the present invention is to provide a method for designing the structural parameters of a rain-collecting root zone irrigation device to solve the technical problem of low rainwater utilization efficiency in the existing technology when performing rain-collecting root zone irrigation for afforestation seedlings in arid areas.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for designing structural parameters of a rainwater collecting root zone supplementary irrigation device is disclosed. The method is used to design the structural parameters of the rainwater collecting root zone supplementary irrigation device. The structural parameters of the rainwater collecting root zone supplementary irrigation device include a rainwater collecting surface area, a water storage tank volume, and a rated flow rate of a ceramic emitter. The method specifically comprises the following steps:

[0007] Step 1: Calculate the amount of rainwater collected by the rainwater collecting root zone irrigation device on day t:

[0008] According to the rainwater collection area, precipitation collection efficiency and precipitation on the tth day, the rainwater collection amount of the rainwater collection root zone irrigation device on the tth day is calculated and obtained using Formula I; the formula I is as follows:

[0009]

[0010] In the formula:

[0011] R t is the rainwater collection amount of the rainwater harvesting root zone supplemental irrigation device on the tth day, with the unit of m 3 .

[0012] P t is the precipitation amount on the tth day, with the unit of mm.

[0013] F t is the precipitation loss amount on the tth day, with the unit of mm.

[0014] A is the rainwater harvesting area, with the unit of m 2 .

[0015] E is the precipitation collection efficiency, with the unit of %.

[0016] Step two, calculate the overflow amount on the tth day:

[0017] If the sum of the actual water storage amount of the water storage tank on the (t-1)th day and the rainwater collection amount of the rainwater harvesting root zone supplemental irrigation device on the tth day is less than or equal to the water storage tank volume, then the overflow amount on the tth day is 0 according to Formula II-1.

[0018] If the sum of the actual water storage amount of the water storage tank on the (t-1)th day and the rainwater collection amount of the rainwater harvesting root zone supplemental irrigation device on the tth day is greater than the water storage tank volume, then the overflow amount on the tth day is calculated and obtained by using Formula II-2 according to the actual water storage amount of the water storage tank on the (t-1)th day, the rainwater collection amount of the rainwater harvesting root zone supplemental irrigation device on the tth day, and the water storage tank volume.

[0019] The Formula II-1 and Formula II-2 are as follows:

[0020]

[0021] In the formula:

[0022] O t is the overflow amount on the tth day, with the unit of m 3 .

[0023] S is the water storage tank volume, with the unit of m 3 .

[0024] S t-1 is the actual water storage amount of the water storage tank on the (t-1)th day, with the unit of m 3 .

[0025] Step three, calculate the actual water supply amount on the tth day:

[0026] If the sum of the actual water storage amount of the water storage tank on the (t-1)th day and the rainwater collection amount of the rainwater harvesting root zone supplemental irrigation device on the tth day is equal to 0, then the actual water supply amount on the tth day is 0 according to Formula IV-1.

[0027] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collecting root area irrigation device on day t is greater than 0 and less than or equal to the preset water supply on day t, then use formula IV-2 to calculate and obtain the actual water supply on day t.

[0028] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is greater than the preset water supply on day t, the actual water supply on day t is obtained according to formula IV-3.

[0029] The formula IV-1, formula IV-2 and formula IV-3 are shown below:

[0030]

[0031] Where:

[0032] D t The preset water supply volume for day t, in m 3 .

[0033] D t ' is the actual water supply on day t, in m 3 .

[0034] Step 4: Calculate the actual water storage capacity of the water tank on day t:

[0035] If the sum of the actual water storage capacity of the water tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is less than or equal to the volume of the water tank, then use formula III-1 to calculate and obtain the actual water storage capacity of the water tank on day t.

[0036] If the sum of the actual water storage capacity of the water tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is greater than the volume of the water tank, then use formula III-2 to calculate and obtain the actual water storage capacity of the water tank on day t.

[0037] The formula III-1 and formula III-2 are shown below:

[0038]

[0039] Where:

[0040] S t is the water storage capacity of the device on day t, in m 3 .

[0041] The preset water supply volume on day t is calculated and obtained using Formula VII; the Formula VII is as follows:

[0042] D t =nQ t Formula VII.

[0043] Where:

[0044] n is the number of ceramic emitters connected to the water storage tank.

[0045] Q t is the rated flow of the ceramic emitter, i.e., the flow of the ceramic emitter on the tth day, in mL h -1 .

[0046] The flow of the ceramic emitter on the tth day is calculated using Equation VIII and obtained; Equation VIII is as follows:

[0047]

[0048] In the formula:

[0049] k is the water conductivity coefficient of the ceramic material, in m day -1 .

[0050] a is the seepage area of the ceramic material, in m 2 .

[0051] l is the seepage path length of the ceramic material, in m.

[0052] H t-1 is the working water head on the t-1th day, in m.

[0053] The present application also has the following technical features:

[0054] Specifically, the method further comprises:

[0055] Step five, calculating the actual total number of days that the rainwater collection root zone supplemental irrigation device cannot meet the use requirements within the total operation period:

[0056] The preset total number of days that the rainwater collection root zone supplemental irrigation device cannot meet the use requirements within the total operation period is assigned a value of 0.

[0057] If the actual water supply amount on the tth day is greater than the reference afforestation seedling water requirement, then the actual total number of days that the rainwater collection root zone supplemental irrigation device cannot meet the use requirements within the total operation period is obtained according to Equation V-1 to be 0.

[0058] If the actual water supply amount on the tth day is less than or equal to the reference afforestation seedling water requirement, then the actual total number of days that the rainwater collection root zone supplemental irrigation device cannot meet the use requirements within the total operation period is calculated using Equation V-2 and obtained.

[0059] Equations V-1 and V-2 are as follows:

[0060]

[0061] In the formula:

[0062] U' is the actual total number of days that the rainwater collection root zone supplemental irrigation device cannot meet the use requirements within the total operation period.

[0063] U is the preset total number of days during the total operation cycle of the rainwater harvesting root area irrigation device that cannot meet the usage requirements.

[0064] ET c It is the water requirement of afforestation seedlings, in mm.

[0065] Step 6: Calculate the safe operation guarantee rate of the rainwater collection root area irrigation device:

[0066] According to the total number of days in the total operation cycle of the rain-collecting root-field supplementary irrigation device and the actual total number of days during which the rain-collecting root-field supplementary irrigation device fails to meet the use requirements, the safe operation guarantee rate of the rain-collecting root-field supplementary irrigation device is calculated and obtained using Formula VI; the Formula VI is as follows:

[0067]

[0068] Where:

[0069] DOR is the device safe operation guarantee rate, in %.

[0070] N is the total number of days of the total operation cycle of the rainwater harvesting root zone irrigation device.

[0071] When the actual water supply on the t day is greater than the water demand of the afforestation seedlings on that day, the rain-collecting root zone irrigation device is in a safe operating state; when the actual water supply on the t day is less than or equal to the water demand of the afforestation seedlings on that day, the rain-collecting root zone irrigation device is not in a safe operating state.

[0072] Specifically, the working water head on day t-1 is calculated and obtained using Formula IX; the Formula IX is as follows:

[0073]

[0074] Where:

[0075] A t is the bottom area of ​​the water tank, in m 2 .

[0076] d is the burial depth of the ceramic emitter, in m.

[0077] Specifically, the water requirement of the afforestation seedlings is calculated and obtained using Formula X; the Formula X is as follows:

[0078] ET c =K c ×ET0 formula Ⅹ.

[0079] Where:

[0080] K c is the crop coefficient; K c The value of is 0.6.

[0081] ET0 is the reference crop evapotranspiration, in mm.

[0082] Specifically, the rain-collecting root zone replenishment device includes a water tank, a rain-collecting tray is installed in the water tank, a ceramic water emitter is provided below the water tank, and the ceramic water emitter and the water tank are connected by a hose; the bottom of the water tank, the ceramic water emitter and the hose are all buried under the ground; the top surface of the rain-collecting tray is the rain-collecting surface, and the rain-collecting surface is exposed on the ground where the device is used; plants are planted on the ground where the device is used, and the water tank and the rain-collecting tray are arranged outside the bottom of the plants.

[0083] Specifically, the water tank includes a water tank main shell, and a water tank bottom plate is integrated at the bottom end of the water tank main shell; a pair of water tank shell extension plates are integrated in the water tank main shell, and the water tank shell extension plates are arranged along the radial direction of the water tank bottom plate, and the pair of water tank shell extension plates are arranged in parallel and opposite to each other; a water tank central tube is integrated at the center of the water tank bottom plate, and the notch of the water tank central tube is exactly opposite to the notch of the water tank main shell, and the space enclosed by the water tank central tube is coaxial with the center hole of the water tank bottom plate; the water tank central tube and the water tank shell extension plate are integrated, and the gap between the pair of water tank shell extension plates and the space enclosed by the water tank central tube are connected and together constitute a water tank opening.

[0084] Specifically, the notch of the rain collecting tray is opposite to the notch of the main shell of the water tank, the central opening of the rain collecting tray is the rain collecting plate mounting port, and the rain collecting tray is mounted on the central tube of the water tank through the rain collecting plate mounting port; the rain collecting tray includes a plurality of upwardly protruding rain collecting prisms, and the plurality of rain collecting prisms are evenly arranged along the circumferential direction, the rain collecting prisms are inclined along the radial direction and the radial outer end thereof is higher than the radial inner end; the connection between two adjacent rain collecting prisms is recessed downward to form a rain collecting trough; a long through hole is provided on the rain collecting tray around the rain collecting plate mounting port, and the long through hole is a confluence inlet.

[0085] Specifically, a pair of soil retaining plates are integrally provided at the edge of the rain collecting tray, and the gap between the pair of soil retaining plates is the notch of the rain collecting tray.

[0086] Specifically, the ceramic emitter includes an emitter lower shell, which is a hollow, flat cylindrical structure. The emitter upper shell is installed in the emitter lower shell. The emitter water inlet is provided on the top of the emitter upper shell. The emitter water inlet is connected to the water storage tank through a hose. The open bottom end of the emitter lower shell is the emitter water outlet. A water seepage sheet is installed in the emitter lower shell, and the water seepage sheet is located between the emitter upper shell and the emitter water outlet.

[0087] Compared with the prior art, the present invention has the following beneficial technical effects:

[0088] (I) This invention proposes, for the first time, that by calculating the daily rainwater collection and utilization behavior within a device under different collection surface areas, storage tank volumes, and ceramic emitter rated flow rates, and with the goal of maximizing the device's safe operation, it is possible to design the structural parameters of a microporous ceramic root zone irrigation device for rainwater collection in arid forests. This invention addresses a gap in the design of structural parameters for rainwater collection root zone irrigation devices and contributes to improving the efficiency of rainwater utilization for rainwater collection root zone irrigation of seedlings in arid regions.

[0089] (II) Since the present invention takes into account the daily rainfall distribution in the area where the device is used, the parameter design results are more accurate, which helps to improve the fruit yield and preservation rate of seedlings in afforestation projects in arid areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is the installation diagram of the rainwater collection root zone irrigation device.

[0091] Figure 2 Schematic diagram of the water tank structure.

[0092] Figure 3 Schematic diagram of the structure of the rainwater collection tray.

[0093] Figure 4 Schematic diagram of the structure of the ceramic water emitter (exploded view).

[0094] Figure 5 Schematic diagram of the structure of the ceramic water emitter.

[0095] Figure 6 Flowchart of calculation for the design method of structural parameters of rainwater harvesting root zone irrigation device.

[0096] Figure 7 This is the distribution map of the applied local standard precipitation index in the mining area of ​​Wuda District, Wuhai City from 2002 to 2020.

[0097] Figure 8 The effects of different water storage tank volumes and rainwater collection areas on the safe operation guarantee rate of the device in drought years, normal years and wet years are demonstrated.

[0098] The meanings of the numbers in the figure are: 1-water tank, 2-rainwater collection tray, 3-ceramic sprinkler, 4-hose, 5-ground, 6-plants.

[0099] 101 - main shell of water tank, 102 - bottom plate of water tank, 103 - extension plate of water tank shell, 104 - center tube of water tank, 105 - opening of water tank, 106 - buckle.

[0100] 201-Rain collecting plate installation port, 202-Rain collecting prism, 203-Rain collecting trough, 204-Converging inlet, 205-Retaining plate.

[0101] 301- emitter lower shell, 302- emitter upper shell, 303- emitter water inlet, 304- emitter water outlet, 305- water seepage plate, 306- water stop washer, 307- emitter lower shell internal thread, 308- emitter upper shell external thread.

[0102] The technical solution of the present invention is further described below in conjunction with embodiments. DETAILED DESCRIPTION

[0103] The technical idea of ​​the present invention is as follows: the present invention simultaneously considers the rainwater collection surface area of ​​the rainwater collection tray (2), the volume of the water storage tank (1), and the ceramic sprinkler (3), and establishes a calculation formula for rainwater collection and utilization behavior in the device on a daily scale. Based on this formula, after given the daily rainfall data, soil physical property parameters, and seedling species of the device usage site, with the goal of maximizing the safe operation guarantee rate of the rainwater collection microporous ceramic root zone irrigation device in dry years, normal years, and wet years, the structural parameters including the rainwater collection surface area, the volume of the water storage tank, and the rated flow of the ceramic sprinkler are designed.

[0104] The calculation formulas for rainwater collection and utilization behavior in the device on a daily scale include the following formulas I, II, III, and IV:

[0105]

[0106] Where: R t is the amount of rainwater collected by the rainwater collecting root zone irrigation device on day t; t is the precipitation on day t; F t is the precipitation loss on day t; A is the rainwater collection area; E is the precipitation collection efficiency; O t is the overflow rate on day t; S is the volume of the water tank; S t-1 is the actual water storage capacity of the water tank on day t-1; D t Preset water supply for day t; D t ' is the actual water supply on day t; S t is the water storage capacity of the device on day t.

[0107] It should be noted that, unless otherwise specified, all components used in the present invention are components known in the art.

[0108] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0109] Example 1:

[0110] This embodiment provides a rainwater collection root zone irrigation device, such as Figure 1 As shown, it includes a water tank 1, a rainwater collecting tray 2 is installed in the water tank 1, a ceramic water emitter 3 is provided below the water tank 1, and the ceramic water emitter 3 and the water tank 1 are connected by a hose 4; the bottom of the water tank 1, the ceramic water emitter 3 and the hose 4 are all buried under the ground 5; the top surface of the rainwater collecting tray 2 is the rainwater collecting surface, and the rainwater collecting surface is exposed on the ground 5 where the device is used; plants 6 are planted on the ground where the device is used, and the water tank 1 and the rainwater collecting tray 2 are arranged outside the bottom of the plants 6.

[0111] As a specific solution of this embodiment, Figure 2 As shown, the water tank 1 includes a water tank main shell 101, which is a cylindrical structure with a notch. The bottom end of the water tank main shell 101 is integrated with a water tank bottom plate 102, which is a circular plate structure with a notch and a center hole. A pair of water tank shell extension plates 103 are integrated into the water tank main shell 101. The water tank shell extension plates 103 are arranged along the radial direction of the water tank bottom plate 102, and the pair of water tank shell extension plates 103 are arranged parallel to each other. The water tank bottom plate 102 A water tank central tube 104 is integrally provided at the center thereof. The water tank central tube 104 is a cylindrical structure with a notch. The notch of the water tank central tube 104 is aligned with the notch of the water tank main shell 101. The space enclosed by the water tank central tube 104 is coaxial with the center hole of the water tank bottom plate 102. The water tank central tube 104 and the water tank shell extension plate 103 are integrated into one piece. The gap between the pair of water tank shell extension plates 103 and the space enclosed by the water tank central tube 104 are connected and together constitute a water tank opening 105.

[0112] As a specific solution of this embodiment, Figure 2 As shown, a buckle 106 is provided at the upper edge of the main shell 101 of the water tank.

[0113] As a specific solution of this embodiment, Figure 3 As shown, the rain collecting tray 2 is a circular structure similar to a folding fan with a slot, and the slot of the rain collecting tray 2 is opposite to the slot of the main shell 101 of the water tank. The central opening of the rain collecting tray 2 is the rain collecting plate mounting port 201, and the rain collecting tray 2 is mounted on the central tube 104 of the water tank through the rain collecting plate mounting port 201; the rain collecting tray 2 includes a plurality of upwardly protruding rain collecting prisms 202, and the plurality of rain collecting prisms 202 are evenly arranged along the circumferential direction. The rain collecting prisms 202 are inclined along the radial direction and their radial outer ends are higher than the radial inner ends; the connection between two adjacent rain collecting prisms 202 is recessed downward to form a rain collecting trough 203; a long through hole similar to a circular fan is provided on the rain collecting tray 2 around the rain collecting plate mounting port 201, and the long through hole is a confluence inlet 204.

[0114] As a specific solution of this embodiment, Figure 3 As shown, a pair of retaining plates 205 are integrally provided at the edge of the rain collecting tray 2 , and the gap between the pair of retaining plates 205 is the notch of the rain collecting tray 2 .

[0115] As a specific solution of this embodiment, Figure 4 and Figure 5 As shown, the ceramic emitter 3 is a button-type microporous ceramic emitter known in the prior art; the ceramic emitter 3 includes an emitter lower shell 301, which is a hollow, flat cylindrical structure. The emitter upper shell 302 is installed in the emitter lower shell 301. The emitter upper shell 302 is provided with an emitter water inlet 303 on the top. The emitter water inlet 303 is connected to the water storage tank 1 through a hose 4. The open bottom end of the emitter lower shell 301 is the emitter water outlet 304. A water seepage sheet 305 is installed in the emitter lower shell 301 and is located between the emitter upper shell 302 and the emitter water outlet 304.

[0116] As a specific solution of this embodiment, Figure 4 and Figure 5 As shown, two water-stopping washers 306 are installed outside the emitter upper shell 302 , and the water-stopping washers 306 are arranged between the emitter upper shell 302 and the emitter lower shell 301 .

[0117] As a specific solution of this embodiment, Figure 4 and Figure 5 As shown, the inner wall of the emitter lower shell 301 is provided with an emitter lower shell internal thread 307 , and the outer wall of the emitter upper shell 302 is provided with an emitter upper shell external thread 308 , which matches the emitter lower shell internal thread 307 .

[0118] Example 2:

[0119] This embodiment provides a method for designing the structural parameters of a rainwater collecting root zone supplementary irrigation device, which is used to design the structural parameters of the rainwater collecting root zone supplementary irrigation device of Example 1. Figure 7 As shown, the method specifically includes the following steps:

[0120] Step 1: Calculate the amount of rainwater collected by the rainwater collecting root zone irrigation device on day t:

[0121] Based on the rainwater collection area, precipitation collection efficiency, and precipitation on day t, the rainwater collection capacity of the rainwater collection root zone irrigation device on day t is calculated using Formula I; Formula I is as follows:

[0122]

[0123] Where:

[0124] R t is the amount of rainwater collected by the rainwater collecting root zone irrigation device on day t, in m 3 .

[0125] P t is the precipitation on the tth day, in mm, and is obtained from the China Meteorological Data Network.

[0126] F t is the precipitation loss on the tth day, in mm, and is obtained from the China Meteorological Data Network.

[0127] A is the catchment area, in m 2 .

[0128] E is the precipitation collection efficiency, in %. In this embodiment, the value of E is 0.78.

[0129] Step 2: Calculate the overflow volume on day t:

[0130] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collection root zone irrigation device on day t is less than or equal to the water storage tank volume, the overflow rate on day t is 0 according to formula II-1.

[0131] If the sum of the actual water storage capacity of the water tank on day t-1 and the rainwater collected by the rainwater collecting root field recharge device on day t is greater than the volume of the water tank, then based on the actual water storage capacity of the water tank on day t-1, the rainwater collected by the rainwater collecting root field recharge device on day t and the volume of the water tank, formula II-2 is used to calculate and obtain the overflow rate on day t.

[0132] The formula II-1 and formula II-2 are shown below:

[0133]

[0134] Where:

[0135] O t is the overflow volume on day t, in m 3 .

[0136] S is the volume of the water tank, in m 3 .

[0137] S t-1 is the actual water storage capacity of the water tank on day t-1, in m 3 .

[0138] Step 3: Calculate the actual water supply on day t:

[0139] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is equal to 0, then the actual water supply on day t is 0 according to formula IV-1.

[0140] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collecting root area irrigation device on day t is greater than 0 and less than or equal to the preset water supply on day t, then use formula IV-2 to calculate and obtain the actual water supply on day t.

[0141] If the sum of the actual water storage capacity of the water storage tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is greater than the preset water supply on day t, the actual water supply on day t is obtained according to formula IV-3.

[0142] The formula IV-1, formula IV-2 and formula IV-3 are shown below:

[0143]

[0144] Where:

[0145] D t The preset water supply volume for day t, in m 3 .

[0146] D t ' is the actual water supply on day t, in m 3 .

[0147] Step 4: Calculate the actual water storage capacity of the water tank on day t:

[0148] If the sum of the actual water storage capacity of the water tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is less than or equal to the volume of the water tank, then use formula III-1 to calculate and obtain the actual water storage capacity of the water tank on day t.

[0149] If the sum of the actual water storage capacity of the water tank on day t-1 and the rainwater collected by the rainwater collecting root zone irrigation device on day t is greater than the volume of the water tank, then use formula III-2 to calculate and obtain the actual water storage capacity of the water tank on day t.

[0150] The formula III-1 and formula III-2 are shown below:

[0151]

[0152] Where:

[0153] S t is the water storage capacity of the device on day t, in m 3 .

[0154] Step 5: Calculate the actual total number of days during the total operating cycle of the rainwater harvesting root zone irrigation device that cannot meet the usage requirements:

[0155] The preset total number of days during the total operation cycle of the rainwater collection root area irrigation device that cannot meet the use requirements is assigned a value of 0.

[0156] If the actual water supply on day t is greater than the reference afforestation seedling water requirement, then according to formula V-1, the actual total number of days during the total operating cycle of the rain-collecting root zone irrigation device that cannot meet the usage requirements is 0.

[0157] If the actual water supply on day t is less than or equal to the reference afforestation seedling water requirement, then use formula V-2 to calculate and obtain the actual total number of days during the total operating cycle of the rain-collecting root zone irrigation device that cannot meet the usage requirements.

[0158] The formula V-1 and formula V-2 are shown below:

[0159]

[0160] Where:

[0161] U' is the actual total number of days during the total operation cycle of the rainwater harvesting root zone irrigation device that cannot meet the usage requirements.

[0162] U is the preset total number of days during the total operation cycle of the rainwater harvesting root area irrigation device that cannot meet the usage requirements.

[0163] ET c It is the water requirement of afforestation seedlings, in mm.

[0164] Step 6: Calculate the safe operation guarantee rate of the rainwater collection root area irrigation device:

[0165] According to the total number of days in the total operation cycle of the rain-collecting root-field supplementary irrigation device and the actual total number of days during which the rain-collecting root-field supplementary irrigation device fails to meet the use requirements, the safe operation guarantee rate of the rain-collecting root-field supplementary irrigation device is calculated and obtained using Formula VI; the Formula VI is as follows:

[0166]

[0167] Where:

[0168] DOR is the device safe operation guarantee rate, in %.

[0169] N is the total number of days of the total operation cycle of the rainwater harvesting root zone irrigation device.

[0170] When the actual water supply on the t day is greater than the water demand of the afforestation seedlings on that day, the rain-collecting root zone irrigation device is in a safe operating state; when the actual water supply on the t day is less than or equal to the water demand of the afforestation seedlings on that day, the rain-collecting root zone irrigation device is not in a safe operating state.

[0171] As a specific solution of this embodiment, the preset water supply amount on day t is calculated and obtained using Formula VII; the Formula VII is as follows:

[0172] D t =nQ t Formula VII.

[0173] Where:

[0174] n is the number of ceramic emitters connected to the water tank. In this embodiment, the value of n is 2, that is, each water tank is connected to two ceramic emitters.

[0175] Q t is the rated flow of the ceramic emitter, that is, the outflow of the ceramic emitter on day t, in m 3 day -1 .

[0176] As a specific solution of this embodiment, according to Darcy's law, the outflow rate of the ceramic emitter on the tth day is calculated and obtained using Formula VIII; the Formula VIII is as follows:

[0177]

[0178] Where:

[0179] k is the discharge coefficient of the ceramic emitter, in m day -1 ;

[0180] a is the seepage area of ​​the ceramic emitter, unit is m 2 ; In this embodiment, the value of a is 0.00126.

[0181] l is the length of the seepage path of the ceramic emitter, in meters. In this embodiment, the value of l is 2.

[0182] H t-1 is the working water head on day t-1, in m;

[0183] As a specific solution of this embodiment, the working water head on day t-1 is calculated and obtained using Formula IX; the Formula IX is as follows:

[0184]

[0185] Where:

[0186] A t is the bottom area of ​​the water tank, in m 2 In this embodiment, A t The value of is 0.04.

[0187] d is the burial depth of the ceramic emitter, in meters. In this embodiment, the value of d is 0.15.

[0188] As a specific solution of this embodiment, the water requirement of the afforestation seedlings is calculated and obtained using Formula X; the Formula X is as follows:

[0189] ET c =Kc ×ET0 formula Ⅹ.

[0190] Where:

[0191] K c is the crop coefficient. In this embodiment, K c The value of is 0.6.

[0192] ET0 is the reference crop evapotranspiration, in mm;

[0193] Effect verification of Example 2:

[0194] The application site of the rainwater collection root zone irrigation device in Example 2 is located in the mining area of ​​Wuda District, Wuhai City. The mining area has an altitude of 1181-1257m, an average annual precipitation of 156.8mm, and an average annual water surface evaporation of 3206mm. It belongs to a typical arid climate. There are 12 mines in the area with a total mining area of ​​29.6873km. 2 .

[0195] like Figure 1 As shown, when in use, the rain collecting tray 2 is flush with the soil surface, and the water storage tank 1 is buried 20 cm into the soil; the ceramic water emitter 3 is connected to the water storage tank 1 with a hose 4, the burial depth d of the ceramic water emitter is 5 cm, and the precipitation collection efficiency E is 0.78.

[0196] The soil type of the application site of the rainwater collection root zone irrigation device is sandy loam with a field water holding capacity of 0.17 cm 3 cm -3 , the wilting coefficient is 0.10cm 3 cm -3 , saturated hydraulic conductivity is 106.1cm day -1 Pinus sylvestris var. mongolica is a commonly used tree in local afforestation projects. It is drought-resistant and heat-resistant. The maximum root length of the seedling is 40 cm and the horizontal width is 20 cm.

[0197] (1) Selection of characteristic precipitation years: The Standard Precipitation Index (SPI) is an important parameter that reflects the precipitation characteristics of different regions. The lower the SPI, the lower the total precipitation in that year and the higher the degree of drought. The SPI can be calculated using the following formula:

[0198]

[0199] Where:

[0200] SPI is the Standardized Precipitation Index.

[0201] X p It is the total monthly precipitation in mm.

[0202] X m It is the multi-year average monthly precipitation, in mm.

[0203] σ is the standard deviation of the total monthly precipitation over many years.

[0204] The SPI value represents the amount of local precipitation resources and is categorized into seven conditions based on the SPI value: extremely wet (>2.00), very wet (1.50 to 1.99), relatively wet (1.00 to 1.49), normal (-0.99 to 0.99), relatively dry (-1.49 to -1.00), very dry (-1.99 to -1.50), and extremely dry (<-2.00). The years corresponding to the lowest, middle, and highest SPI values ​​are designated as dry, normal, and high water years.

[0205] Figure 7 The distribution pattern of the applied standard precipitation index from 2002 to 2020 is shown. Figure 7 As can be seen from the data, the highest and lowest SPI values ​​(-1.23 and 199, respectively) were observed in 2005 and 2018. Furthermore, the SPI value in 2004 was 0.24, which is close to the average SPI value.

[0206] Therefore, 2005, 2004, and 2018 were selected as drought, normal, and wet years, respectively.

[0207] (2) Determination of rated flow of ceramic injector: Figure 5 As shown in the figure, when the discharge coefficient of the ceramic emitter is between 0.1 and 0.3 cm h -1 When the discharge coefficient of the ceramic emitter is greater than 0.3 cm h -1 When the discharge coefficient of the ceramic emitter increases, the operating reliability of the device in different representative years decreases rapidly.

[0208] Therefore, the rainwater collection root zone irrigation device should use a ceramic emitter with a flow coefficient of 0.3 cm h -1 The rated flow rate calculated by formula VIII is 6 mL h -1 The ceramic sprinkler is suitable for the afforestation project in Wuda mining area.

[0209] (3) Determination of rainwater collection area A and water storage tank volume S: -1 ) under the conditions, such as Figure 8Figure 2 shows the impact of different tank volumes and catchment areas on the device's safe operation assurance rate in drought, normal, and wet years. When the tank volume S is less than 25L, the device's operational reliability increases with increasing tank volume S in drought, normal, and wet years. When the tank volume S is greater than 25L, the device's operational reliability remains at 100% for all catchment areas in drought, normal, and wet years.

[0210] Therefore, when the rainwater collecting surface area is 0.5m 2 The water tank capacity is 25L, and the device operation reliability is above 90%, which can be used as the device structural parameters for the afforestation project in Wuda mining area.

Claims

1. A method for designing structural parameters of a rainwater collecting root zone irrigation device, characterized in that: The method is used to design the structural parameters of a rainwater collecting root zone supplementary irrigation device; the structural parameters of the rainwater collecting root zone supplementary irrigation device include the rainwater collecting surface area, the water storage tank volume, and the rated flow rate of the ceramic emitter; The method specifically comprises the following steps: Step 1: Calculate the root zone irrigation device Rainwater collection capacity: According to the rainwater collection area, precipitation collection efficiency and The daily precipitation is calculated using formula I and the water level of the root zone irrigation device is obtained. Rainwater collection amount; the formula I is as follows: Formula I; Where: For the rainwater collection root zone irrigation device Rainwater collection volume per day, in m 3 ; For the Daily precipitation, in mm; For the The amount of water loss from precipitation, in mm; is the catchment area, in m 2 ; is the precipitation collection efficiency, unit is %; Step 2: Calculate the Day overflow flow: Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t If the sum of the rainwater collected is less than or equal to the volume of the water tank, then the first The daily overflow flow is 0; Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t If the sum of the rainwater collected is greater than the volume of the water storage tank, then according to Actual water storage capacity of water storage tank, rainwater collection root area irrigation device t The amount of rainwater collected and the volume of the water storage tank are calculated using formula II-2 and the Sky overflow flow; The formula II-1 and formula II-2 are shown below: ； Where: For the Daily overflow flow, in m 3 ; is the volume of the water tank, in m 3 ; For the Actual water storage capacity of water storage tank per day, unit is m 3 ; Step 3: Calculate the Actual water supply per day: Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t If the sum of the rainwater collected is equal to 0, then the first The actual water supply per day is 0; Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t The sum of the rainwater collected is greater than 0 and less than or equal to the The preset water supply for the day is calculated using formula IV-2 and the Actual water supply per day; Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t The sum of the rainwater collected is greater than The preset water supply volume for the day is obtained according to formula IV-3. Actual water supply per day; The formula IV-1, formula IV-2 and formula IV-3 are shown below: ； Where: For the The preset water supply per day is in m 3 ; For the Actual water supply per day, in m 3 ; Step 4: Calculate the Actual water storage capacity of water storage tank: Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t If the sum of the rainwater collected is less than or equal to the volume of the water tank, then use formula III-1 to calculate and obtain the Actual water storage capacity of the water storage tank; Jordi The actual water storage capacity of the water storage tank and the rainwater collection root area irrigation device t If the sum of the rainwater collected is greater than the volume of the water tank, use formula III-2 to calculate and obtain the Actual water storage capacity of the water storage tank; The formula III-1 and formula III-2 are shown below: ； Where: For the Daily water storage capacity of the device, in m 3 ; The said The preset daily water supply is calculated and obtained using Formula VII; the formula VII is as follows: Formula VII; Where: is the number of ceramic injectors connected to the water tank; is the rated flow of the ceramic injector, i.e. Ceramic emitter outflow per day, unit is m 3 day -1 ; The said The outflow rate of the ceramic emitter is calculated and obtained using Formula VIII; the formula VIII is as follows: Formula VIII; Where: is the water conductivity of ceramic material, unit is m day -1 ; is the seepage area of ​​ceramic material, in m 2 ; The length of the seepage path of the ceramic material, in meters; For the The working head of the day is in m; Step 5: Calculate the actual total number of days during the total operating cycle of the rainwater harvesting root zone irrigation device that cannot meet the usage requirements: The preset total number of days during the total operation cycle of the rainwater harvesting root zone irrigation device that cannot meet the use requirements is assigned a value of 0; Jordi If the actual water supply on the day is greater than the reference afforestation seedling water requirement, then the actual total number of days in which the rainwater collection root zone irrigation device cannot meet the use requirements within the total operation cycle is 0 according to formula V-1; Jordi If the actual water supply per day is less than or equal to the reference afforestation seedling water requirement, then use formula V-2 to calculate and obtain the actual total number of days during the total operation cycle of the rainwater collection root zone irrigation device that cannot meet the use requirements; The formula V-1 and formula V-2 are shown below: ； Where: The actual total number of days during the total operation cycle of the rainwater harvesting root zone irrigation device that cannot meet the usage requirements; The preset total number of days during the total operation cycle of the rainwater harvesting root zone irrigation device that cannot meet the usage requirements; is the water requirement of afforestation seedlings, in mm; The said The working water head per day is calculated and obtained using Formula IX; the formula IX is as follows: Formula IX; Where: is the bottom area of ​​the water tank, in m 2 ; is the burial depth of the ceramic emitter, in m.

2. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 1, characterized in that: The method further includes: Step 6: Calculate the safe operation guarantee rate of the rainwater collection root area irrigation device: According to the total number of days in the total operation cycle of the rain-collecting root-field supplementary irrigation device and the actual total number of days during which the rain-collecting root-field supplementary irrigation device fails to meet the use requirements, the safe operation guarantee rate of the rain-collecting root-field supplementary irrigation device is calculated and obtained using Formula VI; the Formula VI is as follows: Formula VI; Where: is the device safety operation guarantee rate, unit is %; The total number of days of the total operation cycle of the rainwater harvesting root zone irrigation device; When When the actual water supply on the day is greater than the water demand of the afforestation seedlings on the day, the rainwater collection root zone irrigation device is in a safe operating state; When the actual water supply on a day is less than or equal to the water demand of the afforestation seedlings on that day, the rainwater collecting root zone irrigation device is not in a safe operating state.

3. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 1, characterized in that: The water requirement of the afforestation seedlings is calculated and obtained using Formula X; the Formula X is as follows: Formula X; Where: is the crop coefficient; The value of is 0.6; It is the reference crop evapotranspiration, in mm.

4. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 1, characterized in that: The rain-collecting root zone irrigation device comprises a water tank (1), a rain-collecting tray (2) is installed in the water tank (1), a ceramic water emitter (3) is arranged below the water tank (1), and the ceramic water emitter (3) and the water tank (1) are connected via a hose (4); the bottom of the water tank (1), the ceramic water emitter (3) and the hose (4) are all buried under the ground (5); the top surface of the rain-collecting tray (2) is a rain-collecting surface, and the rain-collecting surface is exposed on the ground (5) where the device is used; plants (6) are planted on the ground where the device is used, and the water tank (1) and the rain-collecting tray (2) are sleeved outside the bottom of the plants (6).

5. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 4 is characterized in that: The water tank (1) comprises a water tank main shell (101), the bottom end of the water tank main shell (101) is integrally provided with a water tank bottom plate (102); a pair of water tank shell extension plates (103) are integrally provided in the water tank main shell (101), the water tank shell extension plates (103) are arranged along the radial direction of the water tank bottom plate (102), and the pair of water tank shell extension plates (103) are arranged parallel to each other; a water tank bottom plate (102) is integrally provided at the center thereof. The central tube (104) of the water tank is aligned with the notch of the main shell (101) of the water tank, and the space enclosed by the central tube (104) of the water tank is coaxial with the center hole of the bottom plate (102) of the water tank; the central tube (104) of the water tank is integrated with the extension plate (103) of the water tank shell, and the gap between the pair of extension plates (103) of the water tank shell and the space enclosed by the central tube (104) of the water tank are connected and together form a water tank opening (105).

6. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 4, characterized in that: The notch of the rain collecting tray (2) is aligned with the notch of the main shell (101) of the water storage tank, the central opening of the rain collecting tray (2) is the rain collecting plate mounting opening (201), and the rain collecting tray (2) is sleeved on the central tube (104) of the water storage tank through the rain collecting plate mounting opening (201); the rain collecting tray (2) comprises a plurality of upwardly protruding rain collecting prisms (202), the plurality of rain collecting prisms (202) are evenly arranged along the circumferential direction, the rain collecting prisms (202) are inclined along the radial direction and the radial outer ends thereof are higher than the radial inner ends; the connection between two adjacent rain collecting prisms (202) is recessed downward to form a rain collecting trough (203); a long through hole is provided on the rain collecting tray (2) around the rain collecting plate mounting opening (201), and the long through hole is a converging water inlet (204).

7. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 4, characterized in that: A pair of soil retaining plates (205) are integrally provided at the edge of the rain collecting tray (2), and the gap between the pair of soil retaining plates (205) is the notch of the rain collecting tray (2).

8. The method for designing structural parameters of the rainwater collecting root zone irrigation device according to claim 4, characterized in that: The ceramic emitter (3) comprises an emitter lower shell (301), which is a hollow, flat cylindrical structure. An emitter upper shell (302) is installed in the emitter lower shell (301), and an emitter water inlet (303) is provided on the top of the emitter upper shell (302). The emitter water inlet (303) is connected to the water storage tank (1) through a hose (4). The open bottom end of the emitter lower shell (301) is an emitter water outlet (304). A water seepage sheet (305) is installed in the emitter lower shell (301), and the water seepage sheet (305) is located between the emitter upper shell (302) and the emitter water outlet (304).

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