A method for constructing the horizontal hydrological connectivity index of the intertidal zone in northern China

Abstract

This invention provides a method for constructing a horizontal hydrological connectivity index in the northern intertidal zone, comprising the following steps: collecting surface soil water samples from various tidal zone plots and determining the stable isotope abundance of the surface soil water in each plot; collecting seawater samples at the same time as the surface soil water samples and determining the stable isotope abundance of the seawater; constructing the hydrological connectivity index for each tidal zone plot according to the hydrological connectivity index calculation formula, and comprehensively evaluating the horizontal hydrological connectivity of the northern intertidal zone. The technical solution of this invention, based on stable isotope tracing, constructs a hydrological connectivity index with higher accuracy and sensitivity. Furthermore, by using only the hydrogen and oxygen stable isotope abundance changes as an indicator, the source ratio of multiple water sources in the intertidal zone can be effectively identified, thereby accurately quantifying the hydrological connectivity of the intertidal zone and guiding the eco-hydrological restoration of coastal wetlands.

Description

Technical Field

[0001] This invention relates to the field of ecohydrology technology, and more specifically, to a method for constructing a horizontal hydrological connectivity index in the northern intertidal zone. Background Technology

[0002] Hydrological connectivity refers to the transfer of matter, energy, and organisms through water between or within the various elements of the hydrological cycle. It not only influences the hydrological characteristics of wetlands and shapes their unique habitats, but also affects the structure and function of wetland ecosystems. Under conditions of intense human activity and climate change, changes in hydrological connectivity will alter the distribution patterns of wetland organisms and wetland biogeochemical processes, thereby affecting the health of wetland ecosystems. Hydrological connectivity is constrained by a combination of factors, including hydrodynamics, hydrology, geomorphology, soil, and vegetation.

[0003] Currently, most methods for constructing hydrological connectivity indices focus on in-situ hydrological monitoring, index methods, hydrological models, and graph theory at the watershed scale. These methods are limited to indicators related to hydrology, topography, soil, benthic organisms, and vegetation, and often suffer from the following problems in the process of constructing hydrological connectivity indices:

[0004] (1) Monitoring of multiple factors is time-consuming and requires screening and integration of multiple indicators to indirectly reflect hydrological connectivity.

[0005] (2) It is difficult to quantify hydrological connectivity, and the accuracy and sensitivity are poor. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0007] Therefore, one objective of this invention is to provide a method for constructing a horizontal hydrological connectivity index in the northern intertidal zone. This method constructs a hydrological connectivity index for soil water with seawater as the main source based on the stable isotope characteristics of the water body. It has higher accuracy and sensitivity for quantifying hydrological connectivity, eliminates the need to measure multiple environmental factors, and can accurately, directly, and easily quantify hydrological connectivity based on the dynamic changes of multiple water sources in the intertidal zone.

[0008] To achieve the above objectives, the present invention provides a method for constructing a horizontal hydrological connectivity index in the northern intertidal zone, comprising the following steps: collecting surface soil water samples from various tidal zone plots and determining the stable isotope abundance of the surface soil water in each plot; collecting seawater samples at the same time as the surface soil water samples and determining the stable isotope abundance of the seawater; constructing the hydrological connectivity index for each tidal zone plot according to the hydrological connectivity index calculation formula, and comprehensively evaluating the horizontal hydrological connectivity of the northern intertidal zone, wherein the hydrological connectivity index calculation formula includes:

[0009] HCI X =-|1-δ sample / δ seawater |

[0010] Among them, HCI X Characterized by the hydrological connectivity index constructed using stable isotopes, δ sample Characterized by the abundance of stable isotopes in surface soil water, δ¹⁸O⁻ seawater Characterized by the abundance of stable isotopes in seawater, HCI X The larger the value, the better the hydrological connectivity of the corresponding tidal zone sample plot.

[0011] This technical solution uses water sources from different tidal zones in the intertidal zone as data sources and constructs a hydrological connectivity index using stable isotopes of the water. This facilitates the analysis and quantification of the gradient changes and interannual variations in intertidal hydrological connectivity in wetlands, providing a scientific basis for wetland hydrological connectivity restoration. This method for constructing a horizontal hydrological connectivity index in the northern intertidal zone is applicable to the construction of hydrological connectivity indices in coastal wetlands at different seasons (except spring when the isotopic fractionation effect is strong) and tidal zones. Based on the stable isotope characteristics of the water, it constructs a hydrological connectivity index for soil water with seawater as the main source. This method offers higher accuracy and sensitivity for quantifying hydrological connectivity, eliminates the need for measuring multiple environmental factors, and can accurately, directly, and easily quantify hydrological connectivity based on the dynamic changes of multiple water sources in the intertidal zone.

[0012] Specifically, the source of surface soil water in different tidal flat wetlands was analyzed using stable isotope analysis software (IsoSource). The analysis results are as follows: Figure 1 As shown, Figure 1 The table shows the composition ratio of stable isotope sources of soil water in each tidal flat in each season. It can be seen that the surface soil water of the high tide tidal flat has four sources: precipitation, seawater, groundwater and river water, while the surface soil water of the low tide tidal flat and the middle tide tidal flat has only two sources: precipitation and seawater.

[0013] Based on the geographical location of the study area, the distance from the sea to the low-tide shoals, mid-tide shoals, and high-tide shoals gradually increases, while the distance from the river channel gradually decreases. Therefore, whether river water can affect the surface soil water composition of the mid- and low-tide shoals requires further analysis. The water source of the samples was further analyzed using stable isotope analysis software (IsoSource). If precipitation, seawater, groundwater, and river water are all considered as sources of surface soil water, the results show that the proportion of river water is extremely low (0%–0.8%), indicating that river water does not affect the surface soil water of the mid- and low-tide shoals. However, in the high-tide shoal, IsoSource analysis results show that the proportion of river water ranges from 9.8% to 35.3%, indicating that river water is one of the important sources of surface soil water. Therefore, river water was excluded from the surface soil water source analysis of the mid- and low-tide shoals. Furthermore, when precipitation, seawater, and groundwater are considered as sources of surface soil water, there is no significant distribution pattern between the proportions of seawater and groundwater sources in the mid- and low-tide shoals. One-way ANOVA also shows no significant difference in the abundance of stable isotopes in groundwater and seawater in the mid- and low-tide shoals, as shown in Table 1. Therefore, in the mid- and low-tide shoals, considering both seawater and groundwater as sources of surface soil water simultaneously can lead to source confusion and inaccurate analysis results. In contrast, in the high-tide shoals, there are significant differences between seawater and groundwater in all seasons (P<0.05). Therefore, in the sample plots of the study area, surface soil water in the mid- and low-tide shoals has two sources: precipitation and seawater; surface soil water in the high-tide shoals has four sources: precipitation, seawater, groundwater, and river water.

[0014] Table 1 Comparison of hydrogen and oxygen stable isotope abundance in groundwater and seawater of tidal flats

[0015]

[0016] Note: a and b represent the differences in abundance of the same type of isotope between different water sources (P<0.05).

[0017] This indicates that the main source of surface soil water in the sample plot is seawater. Many factors influence soil water evaporation, such as temperature, sunshine duration, and wind speed. However, since the water samples required for constructing the hydrological connectivity index in different seasons are all collected within a short period during the same season, with minimal differences in climatic conditions, only the duration of seawater infiltration is considered. Therefore, the hydrological connectivity index calculation formula utilizes the ratio of the abundance of stable isotopes in the surface soil water to that in seawater. This results in a hydrological connectivity index with good applicability and seasonal applicability. Moreover, compared to existing technologies, the hydrological connectivity index constructed in this invention can effectively identify the proportion of multiple water sources in the intertidal zone using only the indicator of stable isotope abundance changes. This provides higher accuracy and sensitivity for quantifying hydrological connectivity. Based on ecohydrology, hydrological connectivity can be accurately, directly, and easily quantified according to the dynamic changes in multiple water sources in the intertidal zone.

[0018] In the above technical solution, preferably, the stable isotope is... 2 H or 18 O.

[0019] In this technical solution, stable isotope selection 2 H or 18 O, by collecting seawater, tidal channel water, groundwater, river water, and atmospheric precipitation in different seasons, δD and δ 18 The abundance of O was measured, and the isotopic characteristics of multiple water sources in different seasons were analyzed. The abundance of stable hydrogen and oxygen isotopes varied significantly in different tidal zones and seasons. The use of stable hydrogen and oxygen isotopes further ensured the applicability of the constructed hydrological connectivity index.

[0020] In any of the above technical solutions, preferably, the collection of surface soil water samples from each tidal zone sample plot includes the following steps: interpreting remote sensing images using ENVI software, dividing the intertidal zone into low tidal flats, mid tidal flats, and high tidal flats according to the tidal water level during the tidal process; setting up sample plots in the low tidal flats, mid tidal flats, and high tidal flats respectively, collecting a portion of moist surface soil using a soil sampler, and obtaining surface soil water samples by centrifugation.

[0021] In this technical solution, remote sensing images are interpreted using ENVI software, and the intertidal zone is divided according to the tidal water level during the tidal process. Sample plots are set up in the low tidal flat, mid tidal flat, and high tidal flat to extract surface soil water samples. This makes the various hydrological connectivity indices representative and significantly different, which is conducive to the comprehensive evaluation of the horizontal hydrological connectivity of the northern intertidal zone, and to the analysis and quantification of the changes in the hydrological connectivity gradient and interannual variation characteristics of the wetland intertidal zone, providing a scientific basis for the hydrological connectivity restoration of wetlands.

[0022] In any of the above technical solutions, preferably, surface soil water samples are collected from low tide, mid tide, and high tide samples during the low tide periods in spring, summer, autumn, and winter.

[0023] In this technical solution, surface soil water samples from low tide, mid tide, and high tide areas in spring, summer, autumn, and winter are collected, further enriching the data source for the hydrological connectivity index. This makes it easier to analyze and quantify the changes in the hydrological connectivity gradient and interannual variation characteristics of the intertidal zone of wetlands, providing a scientific basis for the hydrological connectivity restoration of wetlands.

[0024] In any of the above technical solutions, preferably, seawater samples are collected at the natural distribution of seawater during low tide, and the sampling site of the seawater sample is 400m-500m away from the low tide beach sample site.

[0025] This technical solution ensures the correlation between seawater samples and surface soil water samples, which helps improve the accuracy and sensitivity of the hydrological connectivity index.

[0026] In any of the above technical solutions, preferably, the method for constructing the horizontal hydrological connectivity index of the northern intertidal zone further includes: using stable isotope analysis software to analyze the source of surface soil water samples of each tidal zone in each season to determine its main source; if the main source is seawater, then the hydrological connectivity index corresponding to the season and tidal zone is constructed using the hydrological connectivity index calculation formula.

[0027] In any of the above technical solutions, preferably, the step of pre-analyzing the surface soil water samples from each tidal zone in each season using stable isotope analysis software to determine their main sources specifically includes: collecting seawater samples, tidal channel water samples, groundwater samples, and surface soil water samples from low tide, mid tide, and high tide in spring, summer, autumn, and winter; collecting river water samples and precipitation samples in spring, summer, autumn, and winter; collecting seawater samples, tidal channel water samples, groundwater samples, surface soil water samples, and river water samples from the same season at the same time period; and collecting precipitation samples in the same month. Samples were collected during precipitation events preceding other samples. Tidal channel water samples from low-tide, mid-tide, and high-tide shoals were collected from the surface layer in the center of the tidal channels at corresponding locations on each tidal shoal during low tide. Groundwater samples from low-tide, mid-tide, and high-tide shoals were collected during low tide by vertically excavating each tidal shoal until water seeps out. The groundwater depths for low-tide, mid-tide, and high-tide shoals were 0.3–0.5 m, 0.5–0.8 m, and 1–1.5 m, respectively. Stable isotope analysis software was used to analyze the stable isotope characteristics of each sample to determine the compositional proportions of the surface soil water samples and thus identify their primary sources.

[0028] In this technical solution, a source analysis is performed before constructing the hydrological connectivity index of the tidal zone sample plots to determine that the main source is seawater. When the main source is determined to be seawater, the accuracy and sensitivity of constructing the hydrological connectivity index of each tidal zone sample plot using the hydrological connectivity index calculation formula of this invention are higher.

[0029] The method for constructing the horizontal hydrological connectivity index of the intertidal zone in northern China proposed in this invention has the following beneficial technical effects:

[0030] (1) The method for constructing the horizontal hydrological connectivity index of the northern intertidal zone proposed in this invention constructs the hydrological connectivity index of soil water with seawater as the main source based on the stable isotope characteristics of water bodies. It has higher accuracy and sensitivity for quantifying hydrological connectivity, and does not require the measurement of multiple environmental factors. It can accurately, directly and easily quantify hydrological connectivity based on the dynamic change characteristics of multiple water sources in the intertidal zone.

[0031] (2) The hydrological connectivity index constructed in this invention was verified by constructing a hydrological connectivity index using the traditional PCA method. The hydrological connectivity index constructed in this invention has good applicability and can better evaluate the horizontal hydrological connectivity of the intertidal zone in the north, providing a scientific basis for the hydrological connectivity restoration of wetlands.

[0032] (3) The seasonal applicability of the hydrological connectivity index was verified by analyzing the proportion of soil water sources using IsoSource. Compared with existing technologies, the hydrological connectivity index constructed by this invention based on stable isotope ensembles can effectively identify the proportion of multiple water sources in the intertidal zone using only the indicator of hydrogen and oxygen stable isotope abundance changes, thus exhibiting higher accuracy and sensitivity for quantifying hydrological connectivity. Based on ecohydrology, this invention can accurately, directly, and conveniently quantify hydrological connectivity according to the dynamic changes of multiple water sources in the intertidal zone.

[0033] Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description or may be learned by practice of the invention. Attached Figure Description

[0034] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0035] Figure 1 The diagram shows the analysis results of the composition ratio of stable isotopic sources of soil water in each tidal flat in each season.

[0036] Figure 2 A flowchart illustrating a method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention is shown.

[0037] Figure 3The HCI constructed using the method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention is shown. H The correlation verification results with HCI constructed based on the PCA method are shown in the figure.

[0038] Figure 4 The HCI constructed using the method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention is shown. O The correlation verification results with HCI constructed based on the PCA method are shown in the figure.

[0039] Figure 5 The figure shows the regression analysis results of the proportion of seawater source in the surface soil water of sample plots in different seasons calculated by the stable isotope analysis software (IsoSource) and the HCI constructed based on the PCA method.

[0040] Figure 6 This illustrates the construction of the horizontal hydrological connectivity index (HCI) for different seasons using a method for constructing the northern intertidal zone horizontal hydrological connectivity index according to an embodiment of the present invention. H The results of regression analysis verifying the proportion of seawater source in the surface soil water of sample plots in different seasons, calculated by the stable isotope analysis software (IsoSource). Detailed Implementation

[0041] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0042] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0043] Example 1

[0044] like Figure 2 As shown, a method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention includes the following steps:

[0045] S202, collect surface soil water samples from each tidal zone plot, and determine the stable isotope abundance of surface soil water in the corresponding plots.

[0046] S204. Seawater samples were collected at the same time as surface soil water samples to determine the abundance of stable isotopes in seawater.

[0047] S206. Based on the hydrological connectivity index calculation formula, hydrological connectivity indices were constructed for each tidal zone sample plot to comprehensively evaluate the horizontal hydrological connectivity of the northern intertidal zone.

[0048] The formula for calculating the hydrological connectivity index includes:

[0049] HCI X =-|1-δ sample / δ seawater |

[0050] Among them, HCI X Characterized by the hydrological connectivity index constructed using stable isotopes, δ sample Characterized by the abundance of stable isotopes in surface soil water, δ¹⁸O⁻ seawater Characterized by the abundance of stable isotopes in seawater, HCI X The larger the value, the better the hydrological connectivity of the corresponding tidal zone sample plot.

[0051] In this embodiment, using water sources from different tidal zones in the intertidal zone as data sources, a hydrological connectivity index is constructed using stable isotopes of the water body. This method is beneficial for analyzing and quantifying the gradient changes and interannual variations of hydrological connectivity in the intertidal zone of wetlands, providing a scientific basis for the restoration of hydrological connectivity in wetlands. This method for constructing a horizontal hydrological connectivity index in the northern intertidal zone is applicable to the construction of hydrological connectivity indices in coastal wetlands in different seasons (except spring when the isotopic fractionation effect is strong) and different tidal zones. Based on the stable isotope characteristics of the water body, a hydrological connectivity index of soil water with seawater as the main source is constructed. This method has higher accuracy and sensitivity for quantifying hydrological connectivity, eliminates the need for measuring multiple environmental factors, and can accurately, directly, and easily quantify hydrological connectivity based on the dynamic changes of multiple water sources in the intertidal zone.

[0052] Specifically, the source of surface soil water in different tidal flat wetlands was analyzed using stable isotope analysis software (IsoSource). The analysis results are as follows: Figure 1 As shown, Figure 1 The table shows the composition ratio of stable isotope sources of soil water in each tidal flat in each season. It can be seen that the surface soil water of the high tide tidal flat has four sources: precipitation, seawater, groundwater and river water, while the surface soil water of the low tide tidal flat and the middle tide tidal flat has only two sources: precipitation and seawater.

[0053] Based on the geographical location of the study area, the distance from the sea to the low-tide shoals, mid-tide shoals, and high-tide shoals gradually increases, while the distance from the river channel gradually decreases. Therefore, whether river water can affect the surface soil water composition of the mid- and low-tide shoals requires further analysis. Stable isotope analysis software (IsoSource) was used to further analyze the water source of the samples. If precipitation, seawater, groundwater, and river water were all considered as sources of surface soil water, the results showed that the proportion of river water was extremely low (0%–0.8%), indicating that river water does not affect the surface soil water of the mid- and low-tide shoals. However, in the high-tide shoal, IsoSource analysis showed that the proportion of river water ranged from 9.8% to 35.3%, indicating that river water is one of the important sources of surface soil water. Therefore, river water was excluded from the surface soil water source analysis of the mid- and low-tide shoals. Furthermore, when precipitation, seawater, and groundwater are considered as sources of surface soil water, there is no significant distribution pattern in the proportion of seawater and groundwater sources in the mid- and low-tide shoals. One-way ANOVA also shows no significant difference in the abundance of stable isotopes in groundwater and seawater between the low- and mid-tide shoals, as shown in Table 1 above. Therefore, in the mid- and low-tide shoals, considering both seawater and groundwater as sources of surface soil water simultaneously can lead to source confusion and inaccurate analysis results. In contrast, in the high-tide shoals, there are significant differences between seawater and groundwater in all seasons (P<0.05). Therefore, in the sample plots of the study area, surface soil water in the mid- and low-tide shoals has two sources: precipitation and seawater; surface soil water in the high-tide shoals has four sources: precipitation, seawater, groundwater, and river water.

[0054] This indicates that the main source of surface soil water in the sample plot is seawater. Many factors influence soil water evaporation, such as temperature, sunshine duration, and wind speed. However, since the water samples required for constructing the hydrological connectivity index in different seasons are all collected within a short period during the same season, with minimal differences in climatic conditions, only the duration of seawater infiltration is considered. Therefore, the hydrological connectivity index calculation formula utilizes the ratio of the abundance of stable isotopes in the surface soil water to that in seawater. This results in a hydrological connectivity index with good applicability and seasonal applicability. Moreover, compared to existing technologies, the hydrological connectivity index constructed in this invention can effectively identify the proportion of multiple water sources in the intertidal zone using only the indicator of stable isotope abundance changes. This provides higher accuracy and sensitivity for quantifying hydrological connectivity. Based on ecohydrology, hydrological connectivity can be accurately, directly, and easily quantified according to the dynamic changes in multiple water sources in the intertidal zone.

[0055] Furthermore, stable isotopes are 2 H or 18 The abundance of stable hydrogen and oxygen isotopes varies significantly across different tidal zones and seasons. Using stable hydrogen and oxygen isotopes further ensures the applicability of the constructed hydrological connectivity index.

[0056] The ratio of the abundance of stable hydrogen and oxygen isotopes in surface soil water to that in seawater (δ¹⁰) sample / δ seawater This ratio reflects the degree of depletion of stable hydrogen and oxygen isotopes in surface soil water compared to seawater. The closer the ratio is to 1, the lower the degree of depletion, the closer the abundance of stable hydrogen and oxygen isotopes in soil water is to that in seawater, indicating a longer period of seawater cover and stronger hydrological connectivity in the area. The greater the difference between the ratio and 1, the higher the degree of depletion, indicating a shorter period of seawater cover and weaker hydrological connectivity in the area.

[0057] Furthermore, the collection of surface soil water samples from various tidal zone plots includes the following steps: Interpreting remote sensing images using ENVI software, the intertidal zone is divided into low-tide, mid-tide, and high-tide shoals based on tidal water levels during the tidal process; plots are established at each of the low-tide, mid-tide, and high-tide shoals, and moist surface soil is collected using a soil sampler. Surface soil water samples are then extracted by centrifugation. This ensures that the various hydrological connectivity indices are representative and show significant differences, which is beneficial for comprehensively evaluating the horizontal hydrological connectivity of the northern intertidal zone, analyzing and quantifying the gradient changes and interannual variations of intertidal hydrological connectivity in wetlands, and providing a scientific basis for wetland hydrological connectivity restoration.

[0058] Furthermore, surface soil water samples were collected from low-tide, mid-tide, and high-tide shoals during the low tide periods in spring, summer, autumn, and winter. This enriched the data sources for the hydrological connectivity index, making it easier to analyze and quantify the changes and interannual variations in the intertidal hydrological connectivity gradient of wetlands, and providing a scientific basis for the restoration of wetland hydrological connectivity.

[0059] Furthermore, seawater samples were collected at the natural distribution points of seawater during low tide, with the sampling sites located 400-500 meters away from the low tide pad. This ensures the correlation between the seawater samples and the surface soil water samples, which is beneficial for improving the accuracy and sensitivity of the hydrological connectivity index.

[0060] Furthermore, stable isotope analysis software was used beforehand to analyze the source of surface soil water samples from each tidal zone in each season to determine its main source. If the main source was seawater, the hydrological connectivity index corresponding to the season and tidal zone was constructed using the aforementioned hydrological connectivity index calculation formula. This further ensured the higher accuracy and sensitivity of the constructed hydrological connectivity indices for each tidal zone sample plot.

[0061] Example 2

[0062] A method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention includes the following steps:

[0063] Water body information was extracted by interpreting remote sensing images using ENVI software.

[0064] Based on the tidal water level during the tidal process, the intertidal zone is divided into low tide shoals, mid tide shoals, and high tide shoals;

[0065] Seawater, tidal channel water, and groundwater samples were collected from the low tide sections of the low tide, mid tide, and high tide sections during spring, summer, autumn, and winter. Seawater samples were collected from the natural distribution of seawater at low tide, approximately 500m from the low tide sampling site. Tidal channel water samples were collected from the surface layer in the center of the tidal channels at the corresponding locations on each low tide section. Groundwater samples were collected during low tide by vertically excavating each low tide section until water seepage was observed. The groundwater depths for the low, mid, and high tide sections were 0.3–0.5m, 0.5–0.8m, and 1–1.5m, respectively. Simultaneously, quadrats were set up at the low, mid, and high tide sections, and moist surface soil was collected using a soil sampler. Soil water was extracted by centrifugation. River water and precipitation samples were also collected. Precipitation samples for each time period were collected when precipitation events occurred before the collection of other samples in the same month.

[0066] Stable isotope analysis software was used to analyze the stable isotope characteristics of each sample to determine the source composition ratio of surface soil water samples, such as... Figure 1 As shown, the main source of surface soil water in the sample plot is seawater, and the only factor affecting the evaporation conditions of surface soil water is the seawater infiltration time (infiltration time: low tide beach > mid tide beach > high tide beach);

[0067] A hydrological connectivity index for soil water with seawater as the primary source was constructed based on the characteristics of stable isotopes in water bodies. The hydrological connectivity index was constructed using the ratio of the abundance of hydrogen stable isotopes in surface soil water to that in seawater. The formula for calculating the hydrological connectivity index includes:

[0068] HCI H =-|1-δ sample / δ seawater |

[0069] Where, δ sample Characterized by stable isotopes of surface soil water in the sample plot 2 H abundance, δ seawater Characterized as stable isotopes of seawater 2 H abundance, HCI H Characterized by the use of stable isotopes 2 The hydrological connectivity index constructed by H, HCI H The larger the value, the better the hydrological connectivity of the corresponding tidal zone plots. Based on δ, the plots exhibit better connectivity across different seasons. 2 The hydrological connectivity index (HCI) constructed by H HAs shown in Table 2 below,

[0070] Table 2. Based on δ in sample plots during different seasons 2 The hydrological connectivity index (HCI) constructed by H H

[0071]

[0072]

[0073] Hydrological connectivity index (HCI) was constructed based on the PCA method. Nine indicators involving hydrodynamics, soil, and plant community were selected, namely hydrodynamics (erosion rate Re, deposition rate Rd), soil indicators (soil moisture content SWC, soil pH, soil salinity, soil organic matter SOM), and plant community indicators (average plant height Hplant, average plant density Dplant, average plant cover Cplant).

[0074] After collecting hydrological connectivity index data for winter, spring, summer, and autumn, expressions PC for each principal component are established based on the principal component analysis results. n Calculate the scores of each principal component:

[0075] PC n =x1*pH-x2*Salinity-x3*SOM+x4*SWC+x5*Rd+x6*Re+x7*Dplant-x8*Hplant-x9*Cplant

[0076] Based on the explained variance v of each principal component n Principal component score PC n The hydrological connectivity score of a sample plot is calculated, which is the hydrological connectivity index (HCI) of that sample plot: HCI = v1*PC1 + v2*PC2 + ... + v n PC n ;

[0077] For HCI and HCI H Correlation and regression analyses were performed, and the results of the correlation verification are as follows: Figure 3 As shown, HCI and HCI H Although the regression analysis results were poor, the correlation was highly significant (P<0.001). Looking at the seasonal breakdown, except for spring, the HCI values ​​for the other three seasons were... H Both HCI and HCI showed highly significant correlations and good regression relationships (R0). 2 >0.6), indicating that HCI levels are lower in the three seasons other than spring. H Both can effectively characterize the hydrological connectivity of the sample plots.

[0078] Example 3

[0079] A method for constructing the horizontal hydrological connectivity index of the northern intertidal zone according to an embodiment of the present invention includes the following steps:

[0080] Water body information was extracted by interpreting remote sensing images using ENVI software.

[0081] Based on the tidal water level during the tidal process, the intertidal zone is divided into low tide shoals, mid tide shoals, and high tide shoals;

[0082] Seawater, tidal channel water, and groundwater samples were collected from the low tide sections of the low tide, mid tide, and high tide sections during spring, summer, autumn, and winter. Seawater samples were collected from the natural distribution of seawater at low tide, approximately 500m from the low tide sampling site. Tidal channel water samples were collected from the surface layer in the center of the tidal channels at the corresponding locations on each low tide section. Groundwater samples were collected during low tide by vertically excavating each low tide section until water seepage was observed. The groundwater depths for the low, mid, and high tide sections were 0.3–0.5m, 0.5–0.8m, and 1–1.5m, respectively. Simultaneously, quadrats were set up at the low, mid, and high tide sections, and moist surface soil was collected using a soil sampler. Soil water was extracted by centrifugation. River water and precipitation samples were also collected. Precipitation samples for each time period were collected when precipitation events occurred before the collection of other samples in the same month.

[0083] Stable isotope analysis software was used to analyze the stable isotope characteristics of each sample to determine the source composition ratio of surface soil water samples, such as... Figure 1 As shown, the main source of surface soil water in the sample plot is seawater, and the only factor affecting the evaporation conditions of surface soil water is the seawater infiltration time (infiltration time: low tide beach > mid tide beach > high tide beach);

[0084] A hydrological connectivity index for soil water with seawater as the primary source was constructed based on the characteristics of stable isotopes in water bodies. The hydrological connectivity index was constructed using the ratio of the abundance of oxygen stable isotopes in surface soil water to that in seawater. The formula for calculating the hydrological connectivity index includes:

[0085] HCI O =-|1-δ sample / δ seawater |

[0086] Where, δ sample Characterized by stable isotopes of surface soil water in the sample plot 18 O abundance, δ seawater Characterized as stable isotopes of seawater 18 O abundance, HCI O Characterized by the use of stable isotopes 18Hydrological connectivity index (HCI) constructed by O O The larger the value, the better the hydrological connectivity of the corresponding tidal zone plots. Based on δ, the plots exhibit better connectivity across different seasons. 18 Hydrological Connectivity Index (HCI) constructed by O O As shown in Table 3 below,

[0087] Table 3. Based on δ in sample plots during different seasons 18 Hydrological Connectivity Index (HCI) constructed by O O

[0088]

[0089] Hydrological connectivity index (HCI) was constructed based on the PCA method. Nine indicators involving hydrodynamics, soil, and plant community were selected, namely hydrodynamics (erosion rate Re, deposition rate Rd), soil indicators (soil moisture content SWC, soil pH, soil salinity, soil organic matter SOM), and plant community indicators (average plant height Hplant, average plant density Dplant, average plant cover Cplant).

[0090] After collecting hydrological connectivity index data for winter, spring, summer, and autumn, expressions PC for each principal component are established based on the principal component analysis results. n Calculate the scores of each principal component:

[0091] PC n =x1*pH-x2*Salinity-x3*SOM+x4*SWC+x5*Rd+x6*Re+x7*Dplant-x8*Hplant-x9*Cplant

[0092] Based on the explained variance v of each principal component n Principal component score PC n The hydrological connectivity score of a sample plot is calculated, which is the hydrological connectivity index (HCI) of that sample plot: HCI = v1*PC1 + v2*PC2 + ... + v n PC n ;

[0093] For HCI and HCI O Correlation and regression analyses were performed, and the results of the correlation verification are as follows: Figure 4 As shown, HCI O The correlation between HCI and the regression equation was extremely significant (P<0.001), but the R-squared value of the regression equation between the two was... 2 Relatively low. Looking at it seasonally, HCI is lower in winter. O The correlation between HCI and the HCI reached a highly significant level (P<0.001) and a good regression relationship (R0.001). 2=0.82), HCI in summer and autumn O Ri of the regression equation between HCI and HCI 2 The levels were low, but the correlation between the two was highly significant (P < 0.001). HCI only increased in spring. O There was no significant correlation between HCI and HCI (P>0.05). Therefore, HCI is significantly different in summer, autumn and winter. O It can accurately represent the hydrological connectivity of sample plots.

[0094] Example 4

[0095] The proportion of seawater source in the surface soil water samples of the plot, calculated using stable isotope analysis software (IsoSource), was regressed against the hydrological connectivity index (HCI) obtained in Example 2 for different seasons. The regression analysis results are as follows: Figure 5 As shown, except for spring, there is a highly significant correlation between the proportion of seawater source and the hydrological connectivity index (HCI) constructed based on the PCA method in other seasons (P<0.001). The goodness of fit of the regression equation is higher than 0.8, indicating that the calculation results of the stable isotope analysis software (IsoSource) can reasonably characterize the proportion of seawater source in different tidal flat soil water.

[0096] The proportion of seawater source in the surface soil water samples of the plot was analyzed and calculated using stable isotope analysis software, and the hydrological connectivity index (HCI) for different seasons obtained in Example 2 was compared with that obtained in Example 2. H Regression analysis was performed, and the results of the regression analysis were verified as follows: Figure 6 As shown, except for spring, the proportion of seawater sources and the hydrological connectivity index (HCI) constructed based on hydrogen stable isotopes in other seasons are... H There was also a highly significant correlation (P<0.001), and the goodness of fit of the regression equation exceeded 0.7, indicating that from the perspective of the proportion of seawater source, HCI was higher in summer, autumn, and winter. H It can effectively characterize the hydrological connectivity of the sample plot.

[0097] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0099] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing a north intertidal horizontal hydrologic connectivity index, characterized by, Comprising the following steps: Collecting surface soil water samples of each tidal zone sample site, and respectively detecting and determining the stable isotope abundance of the corresponding surface soil water of the sample site, wherein the collecting of the surface soil water samples of each tidal zone sample site comprises the following steps: interpreting the remote sensing image by using the ENVI software, and dividing the intertidal zone into low-tide beach, mid-tide beach and high-tide beach according to the water level of tidal water during the tidal process; setting sample sites on the low-tide beach, mid-tide beach and high-tide beach respectively, collecting part of the wet surface soil by using a soil sampler, and obtaining the surface soil water samples by centrifugal extraction, wherein the surface soil water samples of the low-tide beach, mid-tide beach and high-tide beach sample sites are collected at the low tide period of spring, summer, autumn and winter respectively; Collecting seawater samples at the same period of collecting the surface soil water, and detecting and determining the stable isotope abundance of the seawater; According to the hydrological connectivity index calculation formula, the hydrological connectivity index of each tidal zone sample site is constructed to comprehensively evaluate the horizontal hydrological connectivity of the northern intertidal zone, wherein the hydrological connectivity index calculation formula comprises: HCI X =-|1-δ sample / δ seawater | wherein HCI X characterized as a hydrological connectivity index constructed with stable isotopes, δ sample characterized as the stable isotope abundance of the surface soil water of the sample plot, δ seawater characterized as the stable isotope abundance of seawater, HCI X the greater, the better the hydrological connectivity of the sample plot of the corresponding tidal level, said stable isotope X being 2 H or 18 O, Further comprising: Pre-adopting stable isotope analysis software IsoSource to analyze the sources of the surface soil water samples of each tidal zone in each season, and determining the main source, specifically comprising: collecting seawater samples, tidal ditch water samples, groundwater samples and surface soil water samples of the low-tide beach, mid-tide beach and high-tide beach at the low tide period of spring, summer, autumn and winter respectively; collecting river water samples and precipitation samples in spring, summer, autumn and winter, and collecting the seawater samples, tidal ditch water samples, groundwater samples and surface soil water samples in the same season and the river water samples at the same period; collecting the precipitation samples when the precipitation event occurs before collecting other samples in the same month; collecting the tidal ditch water samples of the low-tide beach, mid-tide beach and high-tide beach at the central surface of the tidal ditch distributed at the corresponding position of each tidal beach during the low tide period; collecting the groundwater samples of the low-tide beach, mid-tide beach and high-tide beach by digging vertically downward until water seeps out during the low tide period, and the groundwater depths of the low-tide beach, mid-tide beach and high-tide beach are 0.3-0.5m, 0.5-0.8m and 1-1.5m respectively; analyzing the stable isotope characteristics of each sample by using the stable isotope analysis software, and determining the source composition ratio of the surface soil water samples to determine the main source; If the main source is seawater, then the hydrological connectivity index corresponding to the season and the tidal zone is constructed by using the hydrological connectivity index calculation formula; Collecting seawater samples at the natural distribution of seawater during the low tide period, and the sampling site of the seawater samples is 400-500m away from the low-tide beach sample site.

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