A method for quantifying important hydrological connectivity areas in estuarine wetlands

Abstract

The present invention discloses a method for quantifying important hydrologically connected areas in estuarine wetlands. First, a tidal gully surface raster image is extracted. Based on the distribution of tidal gullies in the estuarine wetland, the road-shaped water bodies in the tidal gully surface raster image are defined as "roads". Vector data of the road centerline method is used to create road centerline data. The vector data is then processed to obtain multiple tidal gully line elements. Multiple tidal gully patches are then determined using the tidal gully line elements. A distance threshold and a number of selected components are simultaneously determined. The possible connectivity index PC and the overall connectivity index IIC of each tidal gully patch are calculated. The connectivity importance indices Cdiic and Cdpc are used to measure the contribution of a tidal gully patch to the overall hydrological connectivity of the region, ultimately obtaining quantitative results of important hydrologically connected areas in the estuarine wetland. The data of the present invention is easy to obtain, and the analysis method is versatile. It can reduce repetitive manual processing work to a certain extent, providing a reliable analysis tool for scientific researchers.

Description

Technical Field

[0001] The present invention belongs to the technical field of estuarine wetland monitoring, and in particular to a method for quantifying important hydrological connectivity areas of estuarine wetlands. Background Art

[0002] Estuarine wetlands connect river basins with the sea, serving as transition zones between terrestrial river ecosystems and marine ecosystems. They play a significant role in carbon-nitrogen biogeochemical cycling, biodiversity maintenance, global climate change mitigation, and blue carbon sequestration. Hydrology, soils, and plants are the three essential elements for maintaining the ecological functions of estuarine salt marshes. Changes in hydrological connectivity are the most critical factor in connecting and driving these elements, regulating the material cycles, energy transfer, and bioecological processes of water-based ecosystems. Over time, factors such as sea reclamation, land reclamation, and water retention by reservoirs and dams have altered the natural hydrological connectivity and hydrological rhythms of estuarine wetlands, leading to ecosystem degradation and a decline in ecological functions. Understanding the spatiotemporal variations in hydrological connectivity, including tidal channel morphology and water network structure, and particularly quantifying key hydrologically connected areas within estuarine wetlands, will provide a deeper understanding of the coevolutionary characteristics of wetland ecological functions and microtopographic structure.

[0003] Currently, the main method used to quantify the hydrological connectivity of estuarine wetlands is graph theory. This involves digitizing the river network and analyzing the hydrological connectivity of the basin based on the geometric topological relationships between points and lines. The main advantage of graph theory is that it can reflect the spatial heterogeneity of lateral hydrological connectivity in wetlands, making it more valuable for estuarine wetland vegetation restoration. However, it lacks analysis of tidal creek morphological characteristics. Another method quantifies hydrological connectivity based on a tidal creek morphological characteristic index. Specifically, it uses remote sensing imagery to extract tidal creek surface raster images and develops an assessment model by calculating regional parameters such as tidal creek length, bifurcation rate, and curvature. This method can reflect wetland hydrological connectivity patterns to a certain extent, but lacks analysis at a spatial scale. While these two methods can quantify the overall hydrological connectivity of estuarine wetlands, the lack of a unified metric makes it difficult to assess the importance of individual patches, meaning that they cannot accurately quantify areas of significant hydrological connectivity in estuarine wetlands. Summary of the Invention

[0004] The present invention aims to solve the above-mentioned technical problems existing in the prior art and provides a method for quantifying important hydrological connectivity areas of estuarine wetlands.

[0005] The technical solution of the present invention is: a method for quantifying the important hydrological connectivity areas of estuarine wetlands, which is carried out according to the following steps:

[0006] Step 1. Extract the tidal gully surface raster image;

[0007] Step 2. For the extracted tidal gully surface raster image, based on the distribution of tidal gullies in the estuarine wetland, define the road-shaped water body as a "road" and use the road centerline method to create the vector data of the road centerline, that is, the line feature of the road center axis;

[0008] Step 3. Use ArcGIS geometry calculations to obtain the actual length of the road axis line feature. Add the lengths of the connected path polylines within the same visible patch. Take the longest path polyline as a tidal gully line feature. Traverse all visible patches to obtain multiple tidal gully line features.

[0009] Step 4. Determine n tidal gully patches based on multiple tidal gully line features, determine the distance threshold and the number of selected groups, and use the Conefor plug-in in ArcGIS 10.8 software to calculate the possible connectivity index PC and the overall connectivity index IIC of each tidal gully patch. The specific formula is as follows:

[0010]

[0011] Where n is the total number of tidal gully patches in the landscape, i = 1, 2, 3, ... n, j = 1, 2, 3, ... n, i ≠ j; a i and a j are the attributes of tidal gully patches i and j respectively; A L represents the maximum landscape attribute; nl ij is the number of links in the shortest path between i and j; is the maximum product probability of all paths between i and j;

[0012] Step 5. Calculate the connectivity importance index Cdiic and Cdpc. The specific formula is as follows:

[0013]

[0014] Where C i diic and C i dpc represents the importance index of the overall connectivity and possible connectivity of tidal creek patch i, IIC i and PC i It represents the overall connectivity index and possible connectivity index calculated after removing the tidal gully patch i from the entire patch;

[0015] Step 6. Use the spatial interpolation method in ArcGIS 10.8 to calculate the possible connectivity index PC and the overall connectivity index IIC of the spatial area without tidal creek distribution;

[0016] Step 7. In ArcGIS 10.8 software, all calculated values ​​from steps 5 and 6 were combined to obtain the assessment results of the importance of tidal gully patches in the spatial regional hydrological connectivity, that is, the quantitative results of the important hydrological connectivity areas of estuarine wetlands.

[0017] The present invention first extracts a tidal gully surface raster image. Based on the distribution of tidal gullies in estuarine wetlands, the road-shaped water bodies in the tidal gully surface raster image are defined as "roads." The road centerline method is used to create vector data for the road centerlines. The vector data is then processed to obtain multiple tidal gully line features. Furthermore, multiple tidal gully patches are identified using the tidal gully line features. A distance threshold and a number of selected components are also determined. The possible connectivity index PC and the overall connectivity index IIC for each tidal gully patch are calculated. The connectivity importance indices Cdiic and Cdpc are used to measure the contribution of a tidal gully patch to the overall hydrological connectivity of the region. Ultimately, the quantitative results of the important hydrologically connected areas of the estuarine wetland are obtained. The data of the present invention are easily accessible, and the analysis method is versatile, which can reduce repetitive manual processing work to a certain extent, providing researchers with a reliable analysis tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of an embodiment of the present invention.

[0019] Figure 2 This is a distribution map of the importance of Liaohe River estuary patches obtained in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a method for quantifying important hydrological connectivity areas of estuarine wetlands, such as Figure 1 As shown, follow these steps:

[0021] Step 1. Input the Sentinel-2 multispectral image of the study area into the tidal creek extraction model to extract the tidal creek surface raster image;

[0022] The Sentinel-2 multispectral images of the study area are used to determine the geographical and temporal range of tidal creek extraction, and to collect and pre-process high spatial resolution satellite remote sensing image data at high and low tides. The high spatial resolution satellite remote sensing images are Sentinel-2 10-meter spatial resolution remote sensing images.

[0023] The tidal creek extraction model uses a network structure based on deep learning to extract small rivers, and is trained and tested using the Sentinel-2 surface water quality dataset;

[0024] Step 2. For the extracted tidal gully surface raster image, based on the distribution of tidal gullies in estuarine wetlands, we define road-shaped water bodies as "roads." We use the road centerline method to create vector data of the road centerline, i.e., the line feature of the road's central axis. Non-road-shaped water bodies can be ignored to eliminate the influence of non-tidal gully water bodies.

[0025] Step 3. Use ArcGIS to calculate the actual length of the road's central axis line feature. Add the lengths of all connected path polylines within the same visible patch. Take the longest path polyline as a tidal gully line feature. Traverse all visible patches to obtain multiple tidal gully line features, each representing a complete tidal gully.

[0026] Step 4. Determine n tidal gully patches based on multiple tidal gully line features, determine the distance threshold and the number of selected groups, and use the Conefor plug-in in ArcGIS 10.8 software to calculate the probability of connectivity index (PC) and the integral index of connectivity (IIC) of each tidal gully patch. The specific formula is as follows:

[0027]

[0028] Where n is the total number of tidal gully patches in the landscape, i = 1, 2, 3, ... n, j = 1, 2, 3, ... n, i ≠ j; a i and a j are the attributes of tidal gully patches i and j respectively; A L represents the maximum landscape attribute; nl ij is the number of links in the shortest path between i and j; is the maximum product probability of all paths between i and j;

[0029] Step 5. Calculate the connectivity importance indexes Cdiic and Cdpc to measure the contribution of a tidal gully patch to the overall hydrological connectivity of the region. The specific formula is as follows:

[0030]

[0031] Where C i diic and C i dpc represents the importance index of the overall connectivity and possible connectivity of tidal creek patch i, IIC i and PC i It represents the overall connectivity index and possible connectivity index calculated after removing the tidal gully patch i from the overall patch. This index can better reflect the changes in different tidal gully patches in the spatial area;

[0032] Step 6. In order to maintain data consistency, the Inverse Distance Weighting (IDW) spatial interpolation method in ArcGIS 10.8 was used to calculate the possible connectivity index PC and the overall connectivity index IIC for the spatial areas without tidal creeks.

[0033] Step 7. Combine all calculated values ​​from steps 5 and 6 in ArcGIS 10.8 software to obtain the evaluation results of the importance of tidal gully patches in the spatial regional hydrological connectivity, that is, the quantitative results of the important hydrological connectivity areas of estuarine wetlands.

[0034] According to the method of the embodiment of the present invention, the importance distribution map of Liaohekou plaque in different periods is as follows: Figure 2 shown. Figure 2 (a) and (b) are the Liaohe Estuary Patch C in 2016 and 2023, respectively. i diic distribution map, (c) and (d) are the Liaohe Estuary patch C in 2016 and 2023 respectively i dpc distribution chart. Figure 2 The important hydrological connectivity areas of estuarine wetlands can be visually identified, which helps to deeply understand the coordinated evolution characteristics of wetland ecological functions and microtopography structures.

Claims

1. A method for quantifying important hydrological connectivity areas in estuarine wetlands, characterized by Follow these steps: Step 1. Extract the tidal gully surface raster image; Step 2. For the extracted tidal gully surface raster image, based on the distribution of tidal gullies in the estuarine wetland, define the road-shaped water body as a "road". Use the road centerline method to create vector data of the road centerline, that is, the line feature of the road's central axis; Step 3. Use ArcGIS geometry calculations to obtain the actual length of the road axis line feature. Add the lengths of the connected path polylines within the same visible patch. Take the longest path polyline as a tidal gully line feature. Traverse all visible patches to obtain multiple tidal gully line features. Step 4. Determine n tidal gully patches based on multiple tidal gully line features, determine the distance threshold and the number of selected groups, and use the Conefor plug-in in ArcGIS 10.8 software to calculate the possible connectivity index PC and the overall connectivity index IIC of each tidal gully patch. The specific formula is as follows: Where n is the total number of tidal gully patches in the landscape, i = 1, 2, 3, ... n, j = 1, 2, 3, ... n, i ≠ j; a i and a j are the attributes of tidal gully patches i and j respectively; A L represents the maximum landscape attribute; nl ij is the number of links in the shortest path between i and j; is the maximum product probability of all paths between i and j; Step 5. Calculate the connectivity importance index Cdiic and Cdpc. The specific formula is as follows: Where C i diic and C i dpc represents the importance index of the overall connectivity and possible connectivity of tidal creek patch i, IIC i and PC i It represents the overall connectivity index and possible connectivity index calculated after removing the tidal gully patch i from the entire patch; Step 6. Use the spatial interpolation method in ArcGIS 10.8 to calculate the possible connectivity index PC and the overall connectivity index IIC of the spatial area without tidal creek distribution; Step 7. In ArcGIS 10.8 software, all calculated values ​​from steps 5 and 6 were combined to obtain the assessment results of the importance of tidal gully patches in the spatial regional hydrological connectivity, that is, the quantitative results of the important hydrological connectivity areas of estuarine wetlands.

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