Coastal saline-alkali soil water storage system device and application thereof

Abstract

According to the coastal saline-alkali soil water storage system device and the application thereof, on the basis of the characteristics that water and salt in coastal saline-alkali soil are actively transported, and the salinity change amplitude in an irrigation canal is large, ground surface reservoirs of different sizes are laid between field parcels, and the water flow direction of the reservoirs is judged through real-time conductivity data of pond water, canal water and irrigation water; the salt gradient controllable water storage system is formed and controlled according to salt tolerance threshold values of nearby crops, so that the irrigation and salt leaching requirements of different crops in different seasons are met. The water storage device can input the capacities of different reservoirs, crop salt tolerance thresholds, irrigation water demand and the like, estimates the field covered by the water storage device, and optimizes the cultivation mode planning. The device can accumulate irrigation water in different salinity ranges under the condition that the salinity of a surface water body changes drastically, can fully utilize different water sources such as surface water and rainwater, and is very suitable for coastal salinization farmland with relatively rich water resources.

Description

Technical Field

[0001] The present invention belongs to the field of agricultural water resource utilization in coastal saline-alkali land, specifically relates to the technology of multi-source water utilization in saline-alkali land, and particularly relates to a water storage system device for coastal saline-alkali land, which can dynamically control the salinity in the water tank and provide irrigation water suitable for the growth of different crops. Background Art

[0002] In coastal areas, the water-salt migration is active, and the salinity of surface water bodies fluctuates greatly, which severely limits the utilization of water resources in saline-alkali land. First, the degree of salinization in coastal areas is high, and the soil salt distribution is uneven. Affected by the coastal climate, seawater, and shallow high-mineralization groundwater, the salinization recurs. Second, the salinity of surface water fluctuates greatly, and the fresh water source is uncertain, which affects the irrigation during the critical period of crops. The above reasons seriously restrict the efficient utilization and sustainable development of coastal saline-alkali soil.

[0003] There is abundant surface water in coastal areas, but its salinity is affected seasonally. In coastal saline-alkali land or saline soil areas, the soil salt content is relatively high, and the growth of crops is restricted by the salt in the soil. Therefore, how to effectively provide irrigation water suitable for the salt tolerance attributes of different crops is an important topic for improving the utilization rate of such land and crop yields. The existing technologies cannot accurately control the salinity of the irrigation water source according to the salt tolerance attributes of crops, resulting in unsatisfactory irrigation effects and affecting crop yields and quality. Developing a water storage device for coastal saline-alkali land is an important method for coastal saline-alkali soil improvement, treatment, and water resource utilization. At the same time, using irrigation to periodically suppress salt can prevent the recurrence of salinization and improve the utilization rate of water and fertilizer resources, which is an important way to achieve the efficient and sustainable utilization of coastal saline-alkali soil.

[0004] The existing Chinese invention with the application number CN201910767233.7 discloses a method for a rainwater-collecting and salt-isolating solar greenhouse for vegetable production in saline-alkali areas. By arranging a greenhouse wall, a skylight, an inclined soil slope, a water storage trench, a water collecting pipe, etc., it collects fresh water resources, realizes fresh water supply and effective utilization of in-situ soil, combines rainwater collection technology with salt reduction technology to form an integrated technology system, and achieves rainwater collection, reduces the humidity in the greenhouse, and does not affect normal vegetable production and other requirements.

[0005] The existing Chinese invention with the application number CN202410039064.6 discloses a rainwater-collecting solar greenhouse for saline-alkali land and its control method. It adopts a water storage system, a pipeline system, and a central control system. By adding a rainwater collection pool, it improves the utilization efficiency of fresh water. Combining with the central control system to adjust the root environment temperature, it avoids poor plant growth caused by high temperature and improves the water utilization efficiency at the same time.

[0006] The existing Chinese invention with the application number CN201410741683.6 discloses a method for improving saline-alkali land by engineering-chemistry-biology-desalination water-saving-information technology. It gradually reduces the soil salt content through engineering measures according to the implementation steps for salts, improves the utilization efficiency of brackish water resources in saline-alkali land, and comprehensively realizes the transformation of saline-alkali land by combining agronomic, information, and chemical and biological technologies.

[0007] Judging from the situation reflected by the above existing technologies, at present, the utilization of multi-water resources in coastal saline-alkali land mainly realizes the satisfaction of irrigation water through methods such as rainwater harvesting or desalination of saline water. There are still the following deficiencies: (1) The cost of desalinating saline water is relatively high, and the main technical parameters tend to facility agriculture; (2) The crop planting patterns in coastal saline-alkali land change greatly, and the water resource utilization methods cannot flexibly adapt to them; (3) The existing methods lack technologies for the coordination of multiple water sources and cannot meet the irrigation requirements of a large area. Summary of the Invention

[0008] Technical problems to be solved: In view of the problems of high soil salt content and drastic changes in the salinity of irrigation water sources in coastal saline-alkali land, the present invention provides a water storage system device for coastal saline-alkali land and its application. The system stores irrigation water with different salinity thresholds in multiple pools respectively, dynamically monitors and adjusts the salinity in the pools, ensures the provision of suitable irrigation water for different crops, and thus improves the yield and quality of crops.

[0009] Technical solution: A water storage system device for coastal saline-alkali land includes: a water channel for connecting an external water source and a water storage unit; at least two water storage units with different salinities, each water storage unit is respectively connected to the water channel through a water inlet pipe and a drain pipe provided with a water pump; in the water channel, a salinity sensor is arranged between the water inlet pipe and the drain pipe of each water storage unit for real-time monitoring of the salinity of the water flowing through the water channel; each water storage unit includes a reservoir, and a salinity control system is configured in the reservoir. The system further includes a water level sensor, a salinity sensor, and a control unit; the salinity control system automatically adjusts the start and stop of the water pump according to the preset salinity threshold and the real-time salinity data provided by the salinity sensor through a predetermined algorithm or logic program in the control unit to achieve precise control of the water quality salinity in the water channel and the reservoir; among them, the predetermined program includes but is not limited to determining the start, stop, or adjustment of the flow rate of the water pump based on the comparison result between the real-time salinity and the preset threshold, so as to ensure that the water quality in the reservoir and the water quality flowing into the water channel meet the predetermined water quality requirements.

[0010] The above salinity control system further includes a communication module for remotely transmitting the real-time monitored salinity data, water level data, and the working status of the water pump to a central control room or a mobile monitoring device.

[0011] A communication pipe is provided between the above water storage units, allowing water body exchange when necessary to further optimize salinity management.

[0012] A stirring device can be added to the above-mentioned reservoir to promote the uniform distribution of salts in the water body when needed.

[0013] The above-mentioned reservoir is respectively provided with a low-salinity reservoir B and a medium-salinity reservoir A. The salinity threshold of the low-salinity reservoir B is below 1‰, and the salinity threshold of the medium-salinity reservoir A is below 3‰.

[0014] The salinity control of the above-mentioned pool is set with different gradients, and the gradients are 2.2 dS / m (1 g / L) and 10.8 dS / m (5 g / L).

[0015] The device adopts a solar power supply system. By configuring a solar panel power supply system to drive the system, the power of the solar power supply system is 0.8 - 1.0 KW.

[0016] For the application of the above-mentioned device, first set the salt tolerance threshold matching the nearby crops, fix the water inlet pipe and the drain pipe in the nearby surface water body and / or water channel respectively, and start the automatic water storage process: when the salinity of the water inlet pipe monitored by the pool salinity sensor is lower than the salt tolerance threshold, turn on the water pump for water storage; when the salinity of the water inlet pipe monitored by the pool salinity sensor is higher than the salt tolerance threshold, turn off the water pump to stop water storage; when the salinity of the reservoir monitored by the pool salinity sensor is higher than the salt tolerance threshold, turn on the water pump for drainage, and select the drainage pool according to the salinity gradient; Irrigation area estimation: when all the water pumps stop, the water volume and salinity in the reservoir are stable. Combining with the salinity of the water inlet pipe, estimate the existing water storage volume in each pool and the irrigable area under the current water supply conditions of the water channel.

[0017] A method for water quality management using the above-mentioned coastal saline-alkali land water storage system device includes, but is not limited to, regularly calibrating the salinity sensor, adjusting the salinity threshold according to seasonal changes, and adjusting the water pump operation strategy according to the water quality report.

[0018] Beneficial effects: (1) Gradient utilization of water sources with different salt contents. (2) Good risk resistance. This method can effectively resist the threats of coastal seasonal drought and saltwater intrusion. (3) Good applicability. This method can use surface water pools for water storage between plots of different sizes. Description of the Drawings

[0019] Figure 1 Schematic diagram of the water storage device.

[0020] Figure 2 Variation law of soil conductivity during conventional irrigation and salinity-gradient irrigation after water storage.

[0021] Figure 3 Comparison of salt control efficiency between conventional irrigation and after water storage.

[0022] Figure 4 Flow chart of the reservoir irrigation optimization model.

[0023] Figure 5 Optimization results of reservoir irrigation and dynamic changes of soil salinity. Specific implementation manners

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0025] Unless otherwise specified, the experimental methods used in the embodiments of the present application are all conventional methods.

[0026] In the following embodiments, unless otherwise specified, all raw materials can be obtained through commercial purchase or conventional methods.

[0027] Reference can be made to a water storage device for coastal saline-alkali land provided in this embodiment.

[0028] Example 1:

[0029] As Figure 1 shown, the water storage device includes a low-salinity reservoir B1 and a medium-salinity reservoir A2. A salinity sensor 3 is equipped in each pool to monitor the salinity in the pool. The control unit 4 adjusts the opening and closing of the water inlet pipe 5 and the drain pipe 6 according to the salinity data fed back by the sensor to keep the salinity in the pool stable within a preset threshold range. The reservoir B1 or the reservoir A2 introduces water through the water inlet pipe pump 7 and discharges water through the drain pipe pump 8. The low-salinity reservoir B1 is mainly used for irrigating salt-sensitive crops; the medium-salinity reservoir A2 is used for irrigating salt-tolerant crops.

[0030] Step 1: First, select a pool layout site in the irrigation area and use a small excavator to dig during the tillage interval without damaging the field soil and crops;

[0031] Specifically, the sizes of the two pools are 40 m × 25 m × 3 m and 20 m × 10 m × 3 m respectively, and the effective water storage capacity is set to 2400 cubic meters;

[0032] Step 2: Lay an anti-seepage cloth in the excavated pool,

[0033] Specifically, the waterproof cloth is made of PVC mesh cloth and is gradually laid with four corners fixed to ensure isolation between the inside and outside of the pool;

[0034] Step 3: Use PVC pipes to install the water inlet and drain outlets according to the relative positions of the field and the pool;

[0035] Specifically, both the water inlet pipe and the drain pipe are DN10 cm and are made of PVC material;

[0036] Step 4: Install the salinity sensor and the water pump;

[0037] Specifically, the salinity sensor is installed according to the actual installation orientation and depth, and the salinity threshold of the low-salinity pool is controlled below 1‰, and the salinity threshold of the medium-salinity pool is 3‰;

[0038] Specifically, the power of the water pump is 0.5 - 0.75 KW, and the model is CHL2 / 4 / 8 / 12 / 15 / 20 horizontal multistage centrifugal stainless steel booster pump, and the control flow range is 4 - 8 m 3 / h;

[0039] Step 5: Install the control system, solar power supply system, etc. on the pool dam or the ridge of the field,

[0040] Specifically, the solar panels can be installed flexibly according to the ridge of the field, and the power is 0.8 - 1.0 KW.

[0041] Example 2:

[0042] The coastal saline-alkali land water storage device provided in this embodiment can refer to Embodiment 1. The difference is that the device of the present invention is used for saline-alkali land treatment projects. The salinity of the low-salinity pool is controlled below 1‰, which is mainly used for irrigating salt-sensitive crops; the salinity of the medium-salinity pool is controlled at about 3‰, which is suitable for irrigating crops with salt-tolerant characteristics. According to the water requirements of crops in different regions, the system will draw appropriate irrigation water from different pools respectively. Among them, the salinity control and adjustment module can be set at different gradients or according to the crop type.

[0043] Test Example 1

[0044] The test area is located in the Tiaozini Reclamation Area, Jiangang Town, Dongtai City, Jiangsu Province. The parent material of the soil in this area is modern sediment, belonging to silty soil. The mass fractions of gravel (2 - 0.22 mm), silt (0.22 - 0.002 mm) and clay (<0.002 mm) are 3.48%, 75.76% and 20.76% respectively. Due to the long-term influence of seawater immersion, the soil salt content is relatively high, and the salt composition is mainly NaCl. The groundwater level in this area is generally high, between 0.8 - 2.4 m, and the groundwater salinity is about 12 g / L. The soil fertility in the research area is low, the soil salinization problem is serious, and the groundwater salinity is high.

[0045] This plot started planting in April 2023. The test period was from April 2023 to November 2023, and the cropping system was rice. The test plot was in the same paddy field, with an area of about 70 mu, and a water storage device was set up. The volumes of the pools were 40 m × 25 m × 3 m and 20 m × 10 m × 3 m, and other devices were arranged as Figure 1 shown.

[0046] The seeding row spacing was 30 cm × 12 cm, with 270,000 hills per hectare, 3 - 4 seedlings per hill, and the seedling age was 3 leaves, transplanted by a mat - type rice transplanter. The application rates of nitrogen (N) fertilizer, phosphorus (P 2 O 5 ) fertilizer, and potassium (K 2 O) fertilizer were 240 kg / hm 2 , 60 kg / hm 2 , 120 kg / hm 2 respectively, and side - deep fertilization was carried out in the field. The soil salinity of 0 - 30 cm was monitored in real - time. During a certain stage, the soil conductivity under four irrigation modes was as Figure 2 shown. Through the step - by - step irrigation with the water storage device in coastal saline - alkali land, the soil conductivity can be effectively reduced. Figure 3 Furthermore, it shows that the step - by - step irrigation can limit the fluctuation range of soil conductivity, and the salt - control efficiency of step - by - step irrigation can reach more than 80%.

[0047] Example 3

[0048] The algorithm in this implementation case refers to the soil properties in Test Example 1. According to the initial salt content and soil physical parameters during planting, the most widely used one - dimensional water - salt transport numerical simulation software for unsaturated zone soil, Hydrus - 1D, at home and abroad, was used to input the measured rainfall and potential evaporation for scenario analysis, and finally the soil moisture assurance rate and salt threshold assurance rate were calculated.

[0049] Step 1: Obtain soil layer properties

[0050] These properties include the hydraulic conductivity of the soil, water - holding characteristics (volumetric water content, field capacity, and wilting point), salt content, and porosity. Soil layer data can usually be obtained through laboratory tests: Conduct laboratory tests on soil samples to measure the hydraulic properties of the soil (for example, through experimental methods such as the hydrostatic head method or the constant - humidity method). It can also be based on existing literature or databases: Consult the soil database (China Soil Database) or the soil property data provided in relevant literature.

[0051] Step 2: Divide the grid and build a model

[0052] In Hydrus 1D, the basis of modeling is to grid the soil in the study area. The purpose of gridding is to discretize the processes of water and salt transport in the soil for convenient computer processing. Select the time step: Determine the time step for the simulation to ensure the accuracy of the calculation. The time step should not be too large, otherwise important water and salt change processes may be ignored; nor should it be too small to avoid excessive computational effort. Select the spatial step: Decide the number of layers in the soil profile. Generally, the depth of the soil profile needs to cover the root activity area, and at the same time, the spatial step should be small enough to accurately simulate the changes in water and salt. Common spatial steps range from 0.05 to 0.1 m.

[0053] Step 3. Simulate irrigation

[0054] Set the irrigation input conditions in Hydrus 1D, including the irrigation water volume, irrigation time, and salt concentration of the irrigation water. The irrigation conditions should be set as much as possible according to actual agricultural irrigation management measures to simulate the actual irrigation effect. Irrigation volume: It can be estimated based on actual irrigation data or meteorological data (such as evapotranspiration). Irrigation water salinity: The salinity of the irrigation water can be set according to the salt concentration in different reservoirs.

[0055] Step 4. Simulate the water and salt transport process

[0056] In Hydrus 1D, set the transport equations for soil water and salt. This step usually includes the following parts: Water transport: Use the Richards equation to describe the flow of water in the soil. This is the most basic transport model in Hydrus 1D. Parameters such as the soil water characteristic curve and evapotranspiration rate need to be input to simulate the vertical flow of water. Salt transport: According to the characteristics of soil salt, Hydrus 1D uses the Advection - Dispersion equation to describe the migration of salt. The input of salt usually comes from irrigation water, precipitation, groundwater, etc., and the deposition, dissolution, diffusion, etc. of salt are considered. Parameters such as the initial salt concentration of the soil and the salt diffusion coefficient need to be input to simulate the water and salt transport process.

[0057] Example 4

[0058] The coastal saline - alkali land water storage device provided in this embodiment can refer to Example 1 and Example 2. The difference is that the device of the present invention is used for the optimization project of saline - alkali land water resource utilization. By establishing a dynamic model of the relationship between the salt change in the reservoir and the measured salt - washing effect, the covering area of the reservoir is estimated to provide support for the planting structure.

[0059] Test Example 2

[0060] The test area is located in the Tiaozini Reclamation Area, Jiangang Town, Dongtai City, Jiangsu Province. The reclamation area has two crops a year, and the common farming methods are wheat-rice and corn-rice. In 2024, it is a corn-rice rotation. According to the salt tolerance thresholds (for corn and rice), the low-salinity reservoir B1 and the medium-salinity reservoir A2 are filled with water. 1-4 times of irrigation for salt washing are carried out during the corn planting period. 4-8 times of irrigation are carried out during the rice planting period. An estimative model of the irrigable area is established according to the dynamic change of the water volume in the reservoir, and meanwhile, the soil salt change is estimated through the average salt reduction rate. With the goal of the soil salt content being lower than 3 g / kg, the coverage area of the water storage system is optimized.

[0061] The calculation process of the model is as Figure 4 shown. The test time is from April 2024 to October 2024, and the cropping system is rice. The vertical variation of the soil texture is not significant, and it is all silty soil. The mass fractions of gravel (2 - 0.22 mm), silt (0.22 - 0.002 mm), and clay (<0.002 mm) are 80.0%, 16.3%, and 3.7% respectively. The vertical variation of the soil salt content is large: 2.63 g / kg at 0 - 10 cm, 6.19 g / kg at 10 - 20 cm, 3.59 g / kg at 20 - 30 cm, 4.85 g / kg at 30 - 40 cm, and 8.07 g / kg at 40 - 50 cm. According to the initial salt content and soil physical parameters, substituting them into the Hydrus-1D model, driving the model with the measured rainfall and potential evaporation, and adding the irrigation water volume and the salt concentration of the irrigation water under the irrigation scenario, the change of soil salt content under different irrigation conditions is simulated (see Example 3). Through calculation, it can be obtained that under the conventional irrigation scenario, the soil salt content drops from 7.2 g / kg to 5.1 g / kg, and its fluctuation range is relatively large. Under the scenario of 6 times of stepped irrigation, the soil salt content drops to 1.4 g / kg, and its fluctuation range is relatively small. Under the scenario of 12 times of stepped irrigation, the soil salt content drops to 0.8 g / kg, and the soil salt content continues to decrease.

[0062] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacement on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A coastal saline-alkali land water storage system device, characterized in that: include: A water channel is used to connect an external water source and a water storage unit; at least two water storage units with different salinities, each water storage unit is connected to the water channel through a water inlet pipe (5) and a drain pipe (6) provided with a water pump; in the water channel, a salinity sensor (3) is provided between the water inlet pipe and the drain pipe of each water storage unit, for real-time monitoring of the salinity of water flowing through the water channel; each water storage unit includes a water reservoir, and a salinity control system is provided in the water reservoir, the system further includes a water level sensor, a salinity sensor and a control unit (4); the salinity control system automatically adjusts the start and stop of the water pump according to a preset salinity threshold and real-time salinity data provided by the salinity sensor through a predetermined algorithm or logic program in the control unit, so as to achieve accurate control of the salinity of water quality in the water channel and the water reservoir; wherein the predetermined program includes but is not limited to determining the start, stop or flow rate of the water pump based on the comparison result of the real-time salinity and the preset threshold, so as to ensure that the water quality in the water reservoir and the water quality flowing into the water channel meet the predetermined water quality requirements.

2. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: The salinity control system further includes a communication module for remotely transmitting the real-time monitored salinity data, water level data and water pump working status to a central control room or a mobile monitoring device.

3. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: Connecting pipes are provided between the water storage units to allow water exchange when necessary to further optimize salinity management.

4. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: A stirring device may be added to the water reservoir to promote uniform distribution of salt in the water when necessary.

5. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: The water reservoirs are respectively provided with a low-salinity water reservoir B (1) and a medium-salinity water reservoir A (2). The salinity threshold of the low-salinity water reservoir B is below 1‰, and the salinity threshold of the medium-salinity water reservoir A is below 3‰.

6. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: The salinity control of the water pool is set with different gradients, which are 2.2 dS / m (1 g / L) and 10.8 dS / m (5 g / L).

7. The coastal saline-alkali land water storage system device according to claim 1, characterized in that: A solar power supply system is used, and a solar panel power supply system is configured to drive the system. The power of the solar power supply system is 0.8-1.0KW.

8. Use of the device according to any one of claims 1 to 7, characterized in that: First, set a salt tolerance threshold that matches the nearby crops, fix the water inlet pipe and the drainage pipe in the nearby surface water body and / or canal respectively, and start the automatic water storage process: when the pool salt sensor monitors that the salinity of the water inlet pipe is lower than the salt tolerance threshold, turn on the water pump to store water; when the pool salt sensor monitors that the salinity of the water inlet pipe is higher than the salt tolerance threshold, turn off the water pump and stop storing water; when the pool salt sensor monitors that the salinity of the reservoir is higher than the salt tolerance threshold, turn on the water pump to drain the water, and select the drainage pool according to the salinity gradient; irrigation area estimation: when all the water pumps stop, the water volume and salinity in the reservoir are stable. Combined with the salinity of the water inlet pipe, estimate the existing water storage in each pool and the irrigable area under the current canal water supply conditions.

9. A method for water quality management using the coastal saline-alkali land water storage system device according to claims 1-7, characterized in that: This includes but is not limited to regular calibration of salinity sensors, adjustment of salinity thresholds based on seasonal changes, and adjustment of pump operation strategies based on water quality reports.

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