Underground water ecological threshold judgment method based on soil salinization prevention and control

Abstract

The invention discloses an underground water ecological threshold judgment method based on soil salinization prevention and control. The method comprises the following steps: acquiring data; respectively determining underground water ecological thresholds by adopting a field measurement method, a dynamic monitoring data deduction method, an ecological process analysis method and a remote sensing interpretation model method; and analyzing the ecological threshold values obtained by each method, determining recommended values of the ecological threshold values, and generating a spatial distribution diagram of the underground water level buried depth ecological threshold value and the underground water TDS ecological threshold value for preventing soil salinization. Based on field measurement, dynamic monitoring data deduction, ecological process analysis and a remote sensing interpretation model, the underground water ecological threshold is scientifically judged from different dimensions, cross validation and comprehensive analysis are carried out on results obtained by multiple methods, the recommendation threshold is finally determined, the limitation of traditional single index or static evaluation is overcome, and the method is suitable for popularization and application. And the comprehensiveness, accuracy and reliability of underground water ecological threshold judgment are ensured.

Description

Technical Field

[0001] This invention relates to the field of groundwater ecological threshold determination in salinized soils, and in particular to a method for determining groundwater ecological threshold based on soil salinization control. Background Technology

[0002] Soil salinization, a prominent land degradation problem globally, is mainly distributed in arid and semi-arid regions and some coastal areas. The formation and evolution of soil salinization are closely related to groundwater dynamics: when the groundwater level is too high (i.e., the groundwater depth is shallow), strong evaporation causes salts dissolved in the groundwater to be transported to the soil surface via capillary upwelling. After water evaporates, salts accumulate on the soil surface, leading to soil structure damage, deterioration of physicochemical properties, and consequently, decreased land productivity and ecological function decline. Soil salinization not only directly affects normal crop growth and causes agricultural yield reduction, but also further induces a series of chain reactions of ecological problems such as regional vegetation degradation, reduced biodiversity, and weakened ecosystem services. Furthermore, human factors such as unreasonable irrigation and groundwater over-extraction further disrupt the natural groundwater salt balance, increasing the complexity and uncertainty of soil salinization risks. Therefore, scientifically determining the groundwater ecological threshold appropriate for soil salinization control is crucial for sustainable land resource management, ensuring ecological security, and promoting high-quality agricultural development.

[0003] Currently, most groundwater threshold determination methods for soil salinization control focus on single-factor analysis, such as static assessments based on individual indicators like groundwater depth or salinity concentration. These methods lack a systematic consideration of the synergistic effects of multiple factors (such as soil texture, climate conditions, vegetation characteristics, and land use patterns), neglecting the dynamic feedback mechanisms and spatial heterogeneity of the soil-groundwater-vegetation system. Consequently, the constructed threshold models suffer from insufficient adaptability and limited accuracy when applied across regions. Furthermore, existing methods are largely based on local point observations and empirical statistics, making it difficult to simulate large-scale, continuous eco-hydrological processes and identify thresholds. Therefore, developing a groundwater ecological threshold determination method that integrates multi-source data, couples eco-hydrological processes, and possesses dynamic assessment capabilities is crucial for improving the predictability and accuracy of soil salinization control. Summary of the Invention

[0004] In view of this, the present invention proposes a groundwater ecological threshold determination method based on soil salinization control, which overcomes the limitations of traditional single index or static assessment, improves the comprehensiveness, accuracy and reliability of groundwater ecological threshold determination, and provides support for regional soil salinization control and ecological protection.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The groundwater ecological threshold determination method based on soil salinization control described in this invention includes the following steps: S1. Obtain topographic features and vegetation cover data of soil salinization areas; obtain groundwater levels, groundwater quality parameters, and soil characteristic parameters of soil salinization areas, soil salinization boundary areas, and soil non-salinization areas. Groundwater quality parameters include total dissolved solids in groundwater, and soil characteristic parameters include soil electrical conductivity, soil particle composition, soil moisture content, soil salt ion content, and total soil salt content. Among these, soil salinization areas, salinization boundary areas, and non-salinization areas are determined based on soil moisture content, soil particle composition, and total soil salt content; and a database is established based on groundwater levels, groundwater quality parameters, and soil characteristic parameters. S2. Based on the data obtained in step S1, the groundwater ecological threshold is determined by the field measurement method, the dynamic monitoring data extrapolation method, the ecological process analysis method, and the remote sensing interpretation model method, respectively. S3. Based on the multiple groundwater ecological thresholds determined in step S2, construct an evaluation system based on "data reliability - spatiotemporal representativeness - model uncertainty", assign weights and scores or conduct consistency tests on ecological thresholds from different sources, screen out convergent grouped data with statistical significance, and determine the groundwater burial depth ecological threshold and groundwater TDS ecological threshold to prevent salinization. S4 generates spatial distribution maps of the ecological thresholds for groundwater level depth and groundwater TDS for preventing soil salinization, as well as threshold value tables and functional relationships corresponding to spatial locations, visually presenting the spatial pattern and quantitative relationship of ecological thresholds for preventing soil salinization.

[0006] Preferably, in S2, the determination of the groundwater ecological threshold using field measurement methods includes the following: drilling soil boreholes in soil salinization areas, soil salinization boundary areas, and soil non-salinization areas to expose the groundwater level, obtaining soil samples, and obtaining groundwater depth data and groundwater TDS for each area. The differences in data among the three areas are compared and analyzed to identify the critical water level and groundwater TDS that lead to the occurrence and development of soil salinization, and to determine the groundwater ecological threshold.

[0007] More preferably, for enclosed watersheds with typical topographic features around ponds and marshes, the ecological threshold for groundwater level depth is determined by measuring the elevation difference between the stable water body boundary of the enclosed lake and the boundary of the adjacent saline soil; the calculation formula for the ecological threshold for groundwater level depth around ponds and marshes is as follows: H eco = H ss ﹣H 0 ; In the formula, Heco The ecological threshold for groundwater level depth. H ss This represents the elevation value at the boundary of the saline soil surrounding the swamp. H 0 This refers to the elevation value at the boundary of a closed lake.

[0008] More preferably, in S2, the method of using dynamic monitoring data to determine the groundwater ecological threshold includes the following: obtaining long-term sequence groundwater level depth and TDS dynamic monitoring data in soil salinization zone, salinization boundary zone and non-salinization zone, and constructing a time series dataset reflecting the dynamic evolution of water and salt in each zone. Based on geographic information technology, the spatial distribution characteristics of groundwater level and groundwater TDS in each area were analyzed; typical groundwater level monitoring wells were selected to analyze the temporal variation characteristics of groundwater level depth. Based on statistical analysis and nonlinear trend fitting models, a quantitative response relationship between groundwater level depth, TDS and soil salinization degree is established, the critical point or inflection point interval of significant change in the boundary state of saline soil is identified, and the groundwater ecological threshold is determined.

[0009] More preferably, in S2, the determination of the groundwater ecological threshold using the ecological process analysis method includes the following: obtaining dynamic monitoring data of groundwater TDS, soil salt ion content, and total soil salinity in soil salinization zone, salinization boundary zone, and non-salinization zone; analyzing the response relationship between groundwater TDS, soil salt ion content, total soil salinity, groundwater depth, and groundwater TDS in each zone; constructing a quantitative mathematical function model with groundwater depth and TDS as automatic variables and total soil salinity as the dependent variable; and determining the groundwater ecological threshold based on the established function model.

[0010] More preferably, in S2, the groundwater ecological threshold is determined by the remote sensing interpretation model method, including the following: acquiring remote sensing image data of the soil salinization area, performing radiometric calibration and atmospheric correction on the remote sensing impact data, and calculating the NDVI, SI and Albedo of the area; The WI and GI were obtained by using the tasseled cap transformation. Based on NDVI, SI, Albedo, WI and GI, a multi-index fusion remote sensing monitoring model for salinization was constructed, including SI+NDVI, WI+SI, WI+NDVI+SI, WI+GI+SI, WI+GI+SI+Albedo and WI+NDVI+SI+Albedo models. The correlation between the model interpretation index and the measured total soil salinity data was compared and analyzed, and the model with the highest correlation was selected. Based on the model with the highest correlation, the spatial distribution information of soil salinization in the target area is extracted. The extracted salinization information is overlaid and analyzed with the spatial distribution data of groundwater depth and groundwater TDS. The groundwater depth in the SDI≥1 area is extracted and statistically analyzed to determine the groundwater ecological threshold.

[0011] Compared with existing technologies, this invention scientifically determines the groundwater ecological threshold from different dimensions based on field measurements, dynamic monitoring data extrapolation, ecological process analysis, and remote sensing interpretation models. Then, it cross-validates and comprehensively analyzes the results obtained from multiple methods to finally determine the recommended threshold. This effectively overcomes the limitations of traditional single indicators or static assessments, improves the comprehensiveness, accuracy, and reliability of groundwater ecological threshold determination, and provides systematic technical support for regional soil salinization prevention and ecological protection. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the present invention. Detailed Implementation

[0013] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0014] It should be noted that, in the description of this invention, relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0015] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0016] like Figure 1As shown, this invention proposes a method for determining groundwater ecological thresholds based on soil salinization prevention and control, comprising the following steps: S1, acquiring data and constructing a multidimensional database; S2, based on the multidimensional database, determining groundwater ecological thresholds (including groundwater level depth ecological thresholds and TDS ecological thresholds) using field measurement, dynamic monitoring data extrapolation, ecological process analysis, and remote sensing interpretation model methods respectively; S3, cross-validating and comprehensively analyzing the calculated groundwater ecological thresholds to determine the groundwater ecological thresholds; S4, outputting spatial distribution maps of groundwater level depth ecological thresholds and TDS ecological thresholds for preventing soil salinization, a table of threshold values ​​corresponding to spatial locations, and functional relationships.

[0017] In this invention, S1 includes the following specific contents: soil boreholes are laid out in a certain area to determine the groundwater level, soil samples are obtained, and corresponding groundwater parameters and soil characteristic parameters are obtained. The groundwater quality parameters include total dissolved solids (TDS), and the soil characteristic parameters include soil electrical conductivity (EC), soil particle composition, soil moisture content, soil salt ion content, and soil total salt content. Based on soil moisture content, soil particle composition and total soil salinity, the region is divided into soil salinization zone, salinization boundary zone and non-salinization zone. A field monitoring network covering the complete salinity gradient space is constructed to facilitate dynamic monitoring of water quality conditions and soil conditions in each zone. This process involves acquiring topographic features and vegetation cover data for soil salinization zones, salinization boundary zones, and non-salinization zones, as well as dynamic monitoring parameters for groundwater level, groundwater quality, and soil properties. The acquired data undergoes cleaning, correction, and standardization to remove or correct erroneous, missing, and outlier values. Data from different sources and formats is converted to a unified format and units to ensure accuracy, standardization, and consistency, effectively improving data quality. The standardized data is then integrated to establish spatial (i.e., soil salinization zones, boundary zones, and non-salinization zones) and attribute-level relationships, constructing a unified and complete multidimensional dataset. When determining groundwater ecological thresholds using various methods, a model can be built based on the multidimensional dataset constructed in S1 to determine the groundwater ecological thresholds.

[0018] In S2 of this invention, the groundwater ecological threshold is determined by field measurement, including the following: based on a field monitoring network covering the complete salinity gradient space, the groundwater level depth, TDS, soil electrical conductivity (EC), soil particle composition, soil moisture content, soil salt ion content, and total soil salinity are obtained for each area; the differences in the data of each indicator in the soil salinization area, salinization boundary area, and non-salinization area are compared and analyzed to identify the critical groundwater level depth and TDS that lead to salinization response in the ecosystem, and the groundwater ecological threshold is determined. For enclosed watersheds with typical topographic features around ponds and marshes, the ecological threshold for groundwater depth to prevent the spread of salt is determined by measuring the elevation difference between the stable water body boundary of the enclosed lake and the boundary of adjacent saline soil. The calculation formula for the ecological threshold for groundwater depth around ponds and marshes is as follows: H eco = H ss ﹣H 0 ; In the formula, H eco The ecological threshold for groundwater level depth. H ss This represents the elevation value at the boundary of the saline soil surrounding the swamp. H 0 (This refers to the elevation value at the boundary of a closed lake.)

[0019] The method of using dynamic monitoring data to determine the groundwater ecological threshold in S2 of this invention includes the following: Based on the long-term sequence of groundwater level depth and TDS dynamic monitoring data in soil salinization zone, salinization boundary zone and non-salinization zone, a time series dataset reflecting the dynamic evolution of water and salt in each zone is constructed. Geographic information technology was used to analyze the spatial distribution characteristics of groundwater depth and groundwater TDS in each area, generating spatial contour maps and spatial variation maps for each area. High-salinity risk areas and key groundwater level control zones were identified (the upper limit of the water level threshold range is for preventing salinization, and the lower limit corresponds to maintaining ecosystem health). Based on the identified high-salinity risk areas and key groundwater level control zones, representative groundwater level monitoring wells in each area were selected to analyze the temporal variation characteristics of groundwater depth, revealing the seasonal fluctuations and long-term evolution trends of groundwater depth. Based on statistical analysis and nonlinear trend fitting models, a functional relationship between groundwater level depth, TDS and total soil salinity is established to reveal the quantitative response relationship between groundwater and soil salinity, identify the critical point or inflection point interval where the boundary state of saline soil changes significantly, and determine the ecological threshold of groundwater.

[0020] The ecological process analysis method used in S2 of this invention to determine the ecological threshold of groundwater includes the following: Based on dynamic monitoring data of groundwater TDS, soil salinity ion content, and total soil salinity obtained from S1 in soil salinization zone, salinization boundary zone, and non-salinization zone, the response relationship between groundwater TDS, soil salinity ion content, total soil salinity, groundwater depth, and groundwater TDS in each zone was analyzed. A quantitative mathematical function model was constructed with groundwater depth and TDS as automatic variables and total soil salinity as the dependent variable. The constructed quantitative mathematical model was calibrated and optimized according to the specific region. Based on the quantitative mathematical function model and the dynamically monitored water-salt parameters (including groundwater TDS, soil salinity ion content, and total soil salinity), the groundwater ecological threshold was determined.

[0021] In S2 of this invention, the groundwater ecological threshold is determined by the remote sensing interpretation model method, including the following: acquiring remote sensing image data of the soil salinization area (including topographic features, vegetation cover and total soluble salts in the soil), performing radiometric calibration and atmospheric correction on the remote sensing impact data, and calculating the vegetation index NDVI, salinity index SI and surface albedo of the area. The KT transform method was used to obtain the humidity index (WI) and green index (GI) of soil salinization areas. Based on the vegetation index (NDVI), salinity index (SI), humidity index (WI), green index (GI), and surface albedo, a multi-index fusion remote sensing monitoring model for salinization was constructed, including the following models: SDI (SI+NDVI), WSI (WI+SI), WNSI (WI+NDVI+SI), WGSI (WI+GI+SI), WGSAI (WI+GI+SI+Albedo), and WNASI (WI+NDVI+SI+Albedo). The correlation between the model interpretation indices and the measured total soil salinity data was compared and analyzed, and the model with the highest correlation was selected. Based on the model with the highest correlation, the spatial distribution information of soil salinization in the salinized area is extracted. The extracted salinization information is overlaid and analyzed with the spatial distribution data of groundwater depth and groundwater TDS. The groundwater depth in the SDI≥1 area is extracted and statistically analyzed to determine the groundwater ecological threshold.

[0022] In step S3 of this invention, the calculated groundwater ecological threshold is cross-validated and comprehensively analyzed to determine the groundwater ecological threshold, including the following specific contents: The groundwater ecological thresholds obtained based on field measurement, dynamic data extrapolation, ecological process analysis, and remote sensing interpretation model are normalized to form a standardized dataset with unified dimensions and comparability, thereby eliminating dimensional effects and scale biases among multi-source data. Based on the data reliability of field measurement methods, the spatiotemporal representativeness of remote sensing interpretation models, and the inherent uncertainty of each method's model, an evaluation system of "data reliability-spatiotemporal representativeness-model uncertainty" is constructed. Consistency tests or one-way ANOVA are used to conduct significance tests and group screening of ecological thresholds obtained from different methods. Convergent group data with statistical significance (i.e., threshold areas with statistical consistency and high reliability) are selected to determine the recommended values ​​for groundwater ecological thresholds to prevent salinization.

[0023] This invention utilizes field monitoring, long-sequence dynamic data analysis, ecological process analysis, and remote sensing interpretation models to construct a multi-perspective groundwater ecological threshold determination system. This system accurately reflects the coupling mechanism and spatial heterogeneity of the soil-groundwater-vegetation system. By establishing a quantitative function model relating soil total salinity, groundwater level depth, and total dissolved solids (TDS), and combining this with remote sensing multi-index fusion to identify the spatial distribution of salinization (multiple remote sensing salinization monitoring models were constructed, and spatial information on salinization was obtained based on the optimal model), and based on weighted or consistency checks, the adaptability, practicality, and spatial coverage of the threshold model are significantly improved. This provides a basis for soil salinization control in different regions and under complex conditions, and overcomes the technical problems of poor applicability and low accuracy of thresholds obtained by traditional methods due to their single element and neglect of system dynamic feedback and spatial heterogeneity.

[0024] In S4 of this invention, a spatial distribution map of the ecological threshold for groundwater level burial depth and the ecological threshold for groundwater TDS used to prevent soil salinization is generated by the system in the GIS platform, along with a table of threshold values ​​and functional relationships corresponding to the spatial location. This visualizes the spatial pattern and quantitative relationship of the ecological threshold for preventing soil salinization, greatly improving the visualization and application convenience of the ecological threshold for preventing soil salinization.

[0025] In practical applications, a salinization risk early warning model can be constructed based on the groundwater ecological threshold for preventing soil salinization determined by this invention. Multiple early warning levels can be set, providing decision support and a time window for managers to take early intervention measures such as intermittent drainage and adjusting irrigation plans. This provides a scientific basis and decision support for the sustainable use of regional land resources, salinization prevention, and ecological security maintenance, as detailed below: (1) For the dynamic regulation of groundwater level, the groundwater ecological threshold determined by this invention is used as the core basis to establish a zoned and differentiated groundwater level regulation mechanism. For example, in sensitive areas where the upper limit of the ecological threshold is easily breached, drainage ditches, underground pipes and other engineering facilities are laid out to actively drain excess groundwater and control the water level below the critical depth of salinization. In areas where there is a risk of the lower limit of the ecological threshold, ecological water replenishment or artificial recharge using flood resources is implemented in a timely manner to ensure the basic needs of vegetation roots for groundwater. This transforms the traditional water level management from a single static control to dynamic and precise regulation based on the ecological threshold.

[0026] (2) For the optimization of irrigation system, promote water-saving and salt-controlling irrigation technologies represented by drip irrigation, micro-sprinkler irrigation and controlled furrow irrigation. Based on soil moisture and groundwater mineralization, formulate and implement precise irrigation plans with "fixed quota, fixed time and fixed frequency". Control the quality of irrigation water source, and carry out necessary treatment or restrict the use of high mineralization water source to reduce salt input from the source and break the vicious cycle of traditional flood irrigation aggravating regional water and salt imbalance.

[0027] (3) For the adaptive adjustment of planting structure, the planting layout of salt-tolerant crops is guided and planned based on the groundwater ecological threshold determined by the present invention. For example, the restoration planting model of "salt-tolerant plants-soil improvement" is promoted in severely saline areas, and the farming system of grain and grass rotation, intercropping and relay cropping is established in light and moderate saline areas to improve the salt tolerance and stability of the entire agricultural ecosystem.

[0028] Finally, it should be emphasized that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the ecological threshold of groundwater based on soil salinization control, characterized in that: The method for determining the groundwater ecological threshold includes the following steps: S1, obtain the topographic features and vegetation cover data of the soil salinization area, and obtain the groundwater level, groundwater quality parameters and soil characteristic parameters of the soil salinization area, salinization boundary area and non-salinization area. The groundwater quality parameters include total dissolved solids in groundwater, and the soil characteristic parameters include soil electrical conductivity, soil particle composition, soil moisture content, soil salt ion content and total soil salt content. Among them, soil salinization zones, salinization boundary zones and non-salinization zones are determined based on soil moisture content, soil particle composition and total soil salinity; a database is established based on groundwater level, groundwater quality parameters and soil characteristic parameters. S2. Based on the data obtained in step S1, the groundwater ecological threshold is determined by the field measurement method, the dynamic monitoring data extrapolation method, the ecological process analysis method, and the remote sensing interpretation model method, respectively. S3. Based on the groundwater ecological threshold obtained in step S2, construct an evaluation system based on "data reliability - spatiotemporal representativeness - model uncertainty", assign weights and scores or conduct consistency tests on the ecological thresholds calculated by different methods, screen out convergent group data with statistical significance, and determine the groundwater burial depth ecological threshold and groundwater TDS ecological threshold to prevent salinization. S4 generates spatial distribution maps of the ecological thresholds for groundwater level depth and groundwater TDS for preventing soil salinization, as well as threshold value tables and functional relationships corresponding to spatial locations, visually presenting the spatial pattern and quantitative relationship of ecological thresholds for preventing soil salinization.

2. The method for determining the ecological threshold of groundwater based on soil salinization control according to claim 1, characterized in that: In S2, the field measurement method is used to determine the groundwater ecological threshold, including the following: soil boreholes are laid in soil salinization area, salinization boundary area and non-salinization area to expose the groundwater level, obtain soil samples and groundwater depth data and groundwater TDS for each area, compare and analyze the data differences of the three areas, identify the critical water level and groundwater TDS that lead to the occurrence and development of soil salinization, and determine the groundwater ecological threshold.

3. The method for determining the ecological threshold of groundwater based on soil salinization control according to claim 2, characterized in that: For enclosed watersheds with typical topographic features around ponds and marshes, the ecological threshold for groundwater level depth is determined by measuring the elevation difference between the stable water body boundary of the enclosed lake and the boundary of adjacent saline soil. The calculation formula for the ecological threshold for groundwater level depth around ponds and marshes is as follows: H eco = H ss ﹣H 0 In the formula, H eco The ecological threshold for groundwater level depth. H ss This represents the elevation value at the boundary of the saline soil surrounding the swamp. H 0 This refers to the elevation value at the boundary of a closed lake.

4. The method for determining the ecological threshold of groundwater based on soil salinization control according to claim 1, characterized in that: In S2, the method of extrapolating dynamic monitoring data to determine the ecological threshold of groundwater includes the following: obtaining long-term sequence groundwater level depth and TDS dynamic monitoring data in soil salinization zone, salinization boundary zone and non-salinization zone, and constructing a time series dataset reflecting the dynamic evolution of water and salt in each zone; Based on geographic information technology, the spatial distribution characteristics of groundwater level and groundwater TDS in each area were analyzed; Typical groundwater level monitoring wells were selected to analyze the temporal variation characteristics of groundwater level depth; Based on statistical analysis and nonlinear trend fitting models, a quantitative response relationship between groundwater level depth, TDS and soil salinization degree is established, the critical point or inflection point interval of significant change in the boundary state of saline soil is identified, and the groundwater ecological threshold is determined.

5. The method for determining the ecological threshold of groundwater based on soil salinization control according to claim 1, characterized in that: In S2, the ecological process analysis method is used to determine the ecological threshold of groundwater, including the following: obtaining dynamic monitoring data of groundwater TDS, soil salt ion content and total soil salinity in soil salinization zone, salinization boundary zone and non-salinization zone; analyzing the response relationship between groundwater TDS, soil salt ion content, total soil salinity and groundwater depth and groundwater TDS in each zone; constructing a quantitative mathematical function model with groundwater depth and TDS as automatic variables and total soil salinity as dependent variable; and determining the ecological threshold of groundwater based on the established function model.

6. The method for determining the ecological threshold of groundwater based on soil salinization control according to claim 1, characterized in that: In S2, the remote sensing interpretation model method is used to determine the ecological threshold of groundwater, including the following: acquiring remote sensing image data of soil salinization areas, performing radiometric calibration and atmospheric correction on the remote sensing impact data, and calculating the NDVI, SI and Albedo of the area; The WI and GI were obtained by using the tasseled cap transformation. Based on NDVI, SI, Albedo, WI and GI, a multi-index fusion remote sensing monitoring model for salinization was constructed, including SI+NDVI, WI+SI, WI+NDVI+SI, WI+GI+SI, WI+GI+SI+Albedo and WI+NDVI+SI+Albedo models. The correlation between the model interpretation index and the measured total soil salinity data was compared and analyzed, and the model with the highest correlation was selected. Based on the model with the highest correlation, the spatial distribution information of soil salinization in the target area is extracted. The extracted salinization information is overlaid and analyzed with the spatial distribution data of groundwater depth and groundwater TDS. The groundwater depth in the SDI≥1 area is extracted and statistically analyzed to determine the groundwater ecological threshold.

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