CN-121581394-B - Regional ecosystem health assessment method based on remote sensing data

CN121581394BCN 121581394 BCN121581394 BCN 121581394BCN-121581394-B

Abstract

The invention relates to the technical field of ecological system health assessment, in particular to a regional ecological system health assessment method based on remote sensing data. The method comprises the steps of obtaining a multi-temporal remote sensing image of a target ecological area, performing band reflectivity processing on the multi-temporal remote sensing image, extracting lake attribute parameters, identifying a hub lake set based on the lake attribute parameters, evaluating the change of the area and vegetation coverage to quantify area ecological degradation so as to comprehensively evaluate the area ecological health index of the current state, regulating and controlling the ecological water level of the hub lake according to the area ecological health index, and formulating an ecological water supplementing scheme of the atrophic lake so as to realize water resource management of a lake group area ecological system. The invention realizes systematic evaluation of ecological health of the lake group by coupling the network topology analysis of the lake group and the water volume space redistribution, so as to accurately identify key hub lakes and support differentiated water resource management.

Inventors

ZHENG YING
CHEN YUXIN
DONG LEI
YANG ZHENQI
ZHANG TIEGANG
YAO ZHENYU
LIU XINYU
ZHAO TIANQI
ZHANG TIEJUN
ZHOU XU

Assignees

水利部牧区水利科学研究所

Dates

Publication Date: 20260508
Application Date: 20251120

Claims (7)

1. The regional ecosystem health assessment method based on the remote sensing data is characterized by comprising the following steps of: Step S1, acquiring multi-time-phase remote sensing images of a target ecological area, performing band reflectivity processing on the multi-time-phase remote sensing images, extracting boundaries of all lakes and calculating geometric and ecological attributes of the boundaries to generate lake attribute parameters, and performing band reflectivity processing on the multi-time-phase remote sensing images in step S1, wherein the steps of extracting the boundaries of all the lakes and calculating the geometric and ecological attributes of the boundaries comprise: performing radiation calibration treatment and atmosphere correction treatment on the multi-temporal remote sensing image so as to generate surface reflectivity image data; extracting near infrared band reflectivity and green band reflectivity from the surface reflectivity image data; Dividing the difference value of the reflectivity of the green light wave band and the reflectivity of the near infrared wave band by the sum of the two to obtain a normalized remote sensing index image; Vectorizing the normalized remote sensing index image, thereby obtaining lake boundary vector data; Step S2, judging the communication relation between the topography and the hydrology among the lakes based on the lake attribute parameters, constructing a lake connectivity matrix, and identifying a hub lake set based on the topological structure of the lake connectivity matrix; step S3, based on the hub lake set and the lake attribute parameters, evaluating the change of the lake area and the vegetation coverage to quantify the regional ecological degradation so as to comprehensively evaluate the regional ecological health index in the current state, wherein the step S3, based on the hub lake set and the lake attribute parameters, evaluating the change of the lake area and the vegetation coverage to quantify the regional ecological degradation comprises the following steps: obtaining the lake area of multiple phases in the lake attribute parameters, and calculating the area change rate; classifying the lakes into a atrophic lake set and an expanding lake set according to the positive and negative of the area change rate; calculating vegetation coverage differences of different time phases according to vegetation coverage in lake attribute parameters; multiplying the absolute value of the area variation by the corresponding vegetation coverage for lakes concentrated in the atrophic lakes to obtain ecological degradation areas; summarizing the ecological degradation areas of all the atrophic lakes to obtain the total area of regional ecological degradation, wherein the step S3 of comprehensively evaluating the regional ecological health index of the current state comprises the following steps: calculating the water level elevation difference value of lakes at two ends of a communicating edge in a lake network topological graph, and giving a water flow direction pointing from a high water level to a low water level to the communicating edge when the water level difference value is greater than zero; Starting from the atrophic lakes in the atrophic lake concentrate, tracking the expanding lakes in the expanding lake concentrate along the water flow direction, and recording the transmission path; establishing a pairing relation from each atrophy lake to each expansion lake according to the transmission path; and S4, regulating and controlling the ecological water level of the hub lake according to the regional ecological health index, and formulating an ecological water supplementing scheme of the atrophic lake to realize water resource management of the regional ecological system of the lake group.
2. The regional ecosystem health assessment method based on remote sensing data according to claim 1, wherein vectorizing the normalized remote sensing index image comprises: Marking pixels with pixel values larger than a preset water body identification threshold value in the normalized remote sensing index image as water body pixels to form water body mask data; Carrying out connected domain analysis on the water mask data, and identifying each connected domain; removing connected domains with the area smaller than the preset minimum lake area, and marking the reserved connected domains as independent lakes; and vectorizing the boundary of each independent lake into lake boundary vector data.
3. The regional ecosystem health assessment method based on remote sensing data according to claim 1, wherein in step S1, the band reflectivity processing is performed on the multi-temporal remote sensing image, and extracting the boundary of each lake and calculating the geometric and ecological attributes thereof further comprises: Calculating the area of a closed area surrounded by each lake boundary vector based on the lake boundary vector data to obtain the lake area of each lake; calculating the geometric center point coordinates in the lake boundary vector data as the lake centroid coordinates of each lake; Acquiring digital elevation model data of a target ecological area; Extracting a water shoreline elevation value at a corresponding position from the digital elevation model data according to the barycenter coordinates of the lakes to serve as the lake water level elevation of each lake; Based on lake boundary vector data, expanding a preset buffer width outwards by taking the boundary as a reference, and correspondingly constructing an ecological buffer zone; Extracting vegetation pixel values of the normalized remote sensing index image in the ecological buffer zone, and calculating an arithmetic average value of all the vegetation pixel values to serve as vegetation coverage; And correlating the lake area, the lake centroid coordinates, the vegetation coverage and the lake water level elevation of each lake to form lake attribute parameters.
4. The regional ecosystem health assessment method based on remote sensing data according to claim 1, wherein in step S2, based on lake attribute parameters, distinguishing the relationship between the topography and the hydrologic connectivity among the lakes, constructing a lake connectivity matrix, and identifying the collection of hub lakes based on the topology of the lake connectivity matrix comprises: extracting the lake centroid coordinates of any two lakes from the lake attribute parameters, and calculating the Euclidean distance between the centroid coordinates of the two lakes as the lake distance; Performing terrain connectivity discrimination according to the inter-lake distance, and marking two lakes as a first lake and a second lake when the two lakes are determined to be in terrain communication; Constructing a terrain section line along the connecting line direction of the centroid coordinates corresponding to the first lake and the second lake; Extracting lake water level elevations corresponding to the first lake and the second lake from the lake attribute parameters, and taking the maximum value of the lake water level elevations and the lake water level elevations as water level threshold values; judging whether a terrain point with an elevation value higher than a water level threshold exists in the terrain section line, and judging that two lakes ground hold have a terrain communication relationship when the terrain point with the elevation value higher than the water level threshold does not exist, and taking the terrain point as a candidate communication lake pair to acquire river network vector data of an area between the candidate communication lake pair; And identifying river channels according to river network vector data, and constructing a lake connectivity matrix according to all the river channels marked by the candidate connected lakes.
5. The method of claim 4, wherein identifying a river channel based on river network vector data comprises: Dividing a first lake buffer zone and a second lake buffer zone respectively based on the ecological buffer zone pair candidate communication lake pairs; Extracting each river vector section in the river network vector data, and judging whether each section of river vector intersects with the first lake buffer zone and the second lake buffer zone at the same time; when a river vector section which simultaneously intersects both the first lake buffer zone and the second lake buffer zone exists, the two lakes ground hold are judged to have a hydrologic communication relationship, and the river vector section is marked as a river channel.
6. The regional ecosystem health assessment method based on remote sensing data according to claim 1, wherein in step S2, based on the lake attribute parameters, distinguishing the relationship between the topography and the hydrologic connectivity among the lakes, constructing a lake connectivity matrix, and identifying the hub lake set based on the topology of the lake connectivity matrix further comprises: Calculating the shortest path between any two lake nodes based on the lake connectivity matrix, and counting node path count values passing through the lake nodes; Calculating the total number of shortest paths among all lake node pairs, dividing the node path count value by the total number of the shortest paths to obtain a median centrality value of the lake nodes; The medium centrality values are arranged in descending order to form a centrality sequencing sequence; Calculating the upper quartile of the centering sequencing sequence as a pivot threshold, and screening lake nodes with the median centering value larger than the pivot threshold to obtain a preliminary pivot lake set; and carrying out priority identification on the preliminary junction lake set, and screening the junction lake set.
7. The regional ecological system health assessment method based on remote sensing data according to claim 1, wherein comprehensively assessing the regional ecological health index of the current state in step S3 further comprises: calculating the ratio of the actual number of connected edges to the theoretical maximum number of connected edges of the network topology graph, and taking the ratio as a network connectivity index; Extracting the area and vegetation coverage of each lake in the hub lake set, and calculating the sum of the products of the area and the vegetation coverage to divide the sum of the products by the total area of the lake group so as to obtain a hub ecological service index; Calculating the average proportion of the successfully paired atrophic lakes and expanded lakes in the pairing relationship to the total number of the lakes so as to obtain the water redistribution balance; Calculating the proportion of the total area of the ecological degradation of the area to the total area of the lake group, and subtracting the proportion from one to obtain an ecological stability index; and carrying out weighted summation on the network connectivity index, the hub ecological service index, the water redistribution balance degree and the ecological stability index to obtain the regional ecological health index.

Description

Regional ecosystem health assessment method based on remote sensing data Technical Field The invention relates to the technical field of ecological system health assessment, in particular to a regional ecological system health assessment method based on remote sensing data. Background The current method for carrying out lake ecology assessment by using remote sensing technology mainly focuses on monitoring physical, chemical and biological parameters of a single lake. However, lakes in nature, especially in plain or wetland areas, often constitute a complex network system, i.e., a lake group network, of interrelated and interacting with each other through various hydraulic links such as surface runoffs, rather than isolated geographical units. In the network, the water quantity or water quality change of any lake node is transmitted to the downstream through the communication channel, so that the cascade response of the whole network is initiated. However, the conventional method tends to consider each lake as an independent evaluation object, calculate the health index of each lake respectively, and then perform simple spatial summarization, and the processing mode breaks the inherent hydraulic and ecological connection between lakes, so that the island type evaluation method cannot identify the root cause of the network structure change, thereby causing serious misjudgment on the lake change cause and failing to realize the regional water resource collaborative management. Disclosure of Invention Based on the above, the present invention provides a regional ecosystem health assessment method based on remote sensing data, so as to solve at least one of the above technical problems. In order to achieve the above purpose, a regional ecosystem health assessment method based on remote sensing data comprises the following steps: step S1, acquiring a multi-temporal remote sensing image of a target ecological area, performing band reflectivity processing on the multi-temporal remote sensing image, extracting the boundary of each lake, calculating the geometric and ecological attributes of each lake, and generating lake attribute parameters; Step S2, judging the communication relation between the topography and the hydrology among the lakes based on the lake attribute parameters, constructing a lake connectivity matrix, and identifying a hub lake set based on the topological structure of the lake connectivity matrix; Step S3, based on the hub lake set and the lake attribute parameters, evaluating the lake area and vegetation coverage change to quantify regional ecological degradation so as to comprehensively evaluate the regional ecological health index in the current state; and S4, regulating and controlling the ecological water level of the hub lake according to the regional ecological health index, and formulating an ecological water supplementing scheme of the atrophic lake to realize water resource management of the regional ecological system of the lake group. The beneficial effects of the invention are as follows: Firstly, based on lake attribute parameters, accurately constructing a lake connectivity matrix reflecting actual hydraulic connection among lakes through terrain profile analysis and river network vector data superposition discrimination. On the basis, a lake network topological graph is further constructed, and hub lakes with decisive effects on the hydrologic connectivity and ecological stability of the whole network are identified by using network analysis algorithms such as medium centrality and the like. The method integrates originally discrete lake units into an organic network system for integral evaluation, and can clearly track how the change of one lake affects other lakes through the communication channel, so that the cascade effect caused by the change of the network structure is identified. The method thoroughly solves the problem of serious misjudgment on the lake change cause caused by the internal connection among the fractured lakes in the traditional island type evaluation method. The invention combines multi-temporal lake area change analysis to identify the 'atrophy lake set' (source) and the 'expansion lake set' (sink) in the area. Furthermore, the water flow direction is determined according to the water level elevation difference between lakes, the water flow transmission path from the shrinking lake to the expanding lake is tracked on the network topological graph, and the space pairing relation between the two water flow paths is established. The method not only counts the total amount of water volume increase and decrease, but also reveals the space transfer pattern of the water volume among lakes, and can clearly answer the core problem of 'which atrophic lakes flow to which expanding lakes', thereby quantifying the balance degree of water volume redistribution. The method solves the problem that the prior art can only carry out macroscopic total amount statistics, but