River physical habitat assessment system based on ArcGIS and RHS

Abstract

The application provides a river physical habitat evaluation system based on ArcGIS and RHS, comprising: a river vector data acquisition module, a river vector data segmentation and numbering module, a river habitat quality present situation investigation module, a river habitat quality evaluation and grade division module, and a river habitat evaluation result input and ArcGIS system management module. The application proposes a targeted ecological restoration countermeasure for a damaged river section in view of the fact that current river habitat evaluation methods cannot accurately evaluate river habitat quality.

Description

TECHNICAL FIELD

[0001] The field of the present application relates to a method for river physical habitat assessment and management based on ArcGIS and RHS. BACKGROUND

[0002] As an important part of river ecosystems, river physical habitat is the material basis and space for the survival of aquatic organisms such as fish. The quality of habitat directly affects the distribution, community structure and functional diversity of aquatic organisms. Effective identification and diagnosis of river physical habitat characteristics and evaluation of river physical habitat quality have important practical significance for developing water ecological restoration measures. Internationally, more representative evaluation systems include the UK's RIVPACS (River Invertebrate Prediction and Classification System), RHS (River Habitat Survey), Sweden's RCE (River Corridor Environment), Australia's AUSRIVAS (Australian River Assessment System) and ISC (Stream Condition Index), etc. Among them, RHS has become the standard survey method recommended by WFD, and is also the most widely used method among many river habitat assessment methods.

[0003] With the gradual deepening of ecological protection concepts, river ecological quality assessment and ecological restoration have become a hot topic in national water ecological research. Compared with foreign countries, river health assessment in China started late. Early research mainly focused on pollution prevention and water quality improvement, and there was insufficient understanding and attention to water ecological systems. In addition, a systematic river habitat survey and evaluation technology system has not yet been established, and most research is at the sample or watershed scale. Therefore, the existing river habitat quality assessment technology needs to be further improved and developed.

[0004] Technical scheme of prior art one

[0005] The application discloses a river ecological quality evaluation method based on remote sensing technology, and provides a river ecological quality evaluation method based on remote sensing technology, which comprises four index units of habitat quality indexes, water quality inversion indexes, landscape structure indexes and biodiversity indexes.

[0006] Disadvantages of prior art one

[0007] The evaluation scale is too macroscopic, and the 0.1-meter high-resolution aerial image required for the evaluation of the river ecological quality based on pure remote sensing technology is difficult to obtain.

[0008] Technical scheme of prior art two

[0009] A city river fish habitat evaluation method and system, on the basis of collecting city river basic data, screening index fish and at least one habitat influence factor corresponding thereto; the city river is divided into at least one river section, and the measured data of at least one habitat influence factor in at least one river section is collected; at least one habitat influence factor is classified according to different life stages of index fish, and the fuzzy set and fuzzy rule of index fish are obtained according to the dominant value of at least one habitat influence factor and the weight of at least one habitat influence factor in the habitat suitability of index fish; the measured data of at least one habitat influence factor is input into the fuzzy set and fuzzy rule of index fish, and the habitat suitability of index fish in at least one river section is obtained.

[0010] Disadvantages of prior art two

[0011] The technology is too limited in application area and is only suitable for city rivers. Summary of the application

[0012] The present application aims at the problems that current river habitat evaluation methods cannot accurately evaluate the current situation of river habitat quality, and cannot track the quality of each river section, and proposes a river physical habitat evaluation system based on ArcGIS and RHS method to specifically propose ecological restoration countermeasures for damaged river sections.

[0013] The present application adopts the following technical solutions:

[0014] A river physical habitat evaluation system based on ArcGIS and RHS comprises:

[0015] S1. Obtain river vector data module

[0016] National basic geographic information database has river vector data of the evaluation area, then directly perform kml file conversion and rectification; if not, 1) download DEM data of the evaluation area according to latitude and longitude range; 2) merge the downloaded DEM data; 3) obtain river vector data through hydrological analysis; 4) delete other sub-basins and water networks outside the evaluation river system and basin through the "Editor" in ArcGIS to generate the final river system data; 5) rectify the vector data of the evaluation river using satellite image.

[0017] Specifically, the national basic geographic information database has river vector data of the evaluation area, then directly perform kml file conversion and rectification; if not, 1) download DEM data of the evaluation area according to latitude and longitude range; 2) merge the downloaded DEM data; 3) obtain river vector data through hydrological analysis; 4) delete other sub-basins and water networks outside the evaluation river system and basin through the "Editor" in ArcGIS to generate the final river system data; 5) rectify the vector data of the evaluation river using satellite image.

[0018] S2. River vector data segmentation and numbering module

[0019] The Edit editing tool of ArcGIS software is used to segment the investigated river, and the segmented vector data of each investigated river is numbered in order from upstream to downstream.

[0020] S3. River habitat quality current situation segmentation investigation module According to the relevant specifications of river habitat investigation, the investigated river is investigated on site, and the investigation content includes two aspects: 1) river habitat quality evaluation; 2) river habitat degradation index evaluation system.

[0021] S4. River habitat quality evaluation and grade division module

[0022] According to the on-site investigation data and satellite image data (unreachable area), the total score of each river section is evaluated, and the cumulative score of each index is the total score of the river section. In theory, the total score of each river section ranges from 0 to 53. The K-means clustering method is used to divide the river section score into five grades of excellent, good, medium, poor and extremely poor, and the division standard of each grade is determined.

[0023] The river habitat quality grading criteria are as follows: the score is greater than or equal to 34, which is "excellent"; the score is between 26.5 and 33.5, which is "good"; the score is between 20.5 and 26, which is "medium"; the score is between 13.5 and 22, which is "poor"; and the score is less than 13, which is "very poor".

[0024] S5. River habitat quality restoration module

[0025] According to the difference between each score and the highest value, the corresponding restoration countermeasures of the surveyed river section can be determined. For example, taking the current state of the river bank and the vegetation of the riparian zone as an example, if the surveyed river section is an eroded river bank with a score of only 0.5, the degraded river bank needs to be restored by planting aquatic plants and appropriately stacking stone blocks of different sizes to consolidate the river bank; if the surveyed river section has no vegetation coverage with a score of 0, the native plants need to be supplemented by referring to the types of surrounding vegetation. The vegetation restoration types in the near-water riparian zone (the water level fluctuation zone between the multi-year average maximum and minimum water level lines of the river) mainly include various aquatic vascular plants (submerged plants, floating-leaved plants, and emergent plants). The vegetation restoration in the terrestrial buffer zone can consider the principles of mixing evergreen and deciduous tree species, matching deep-rooted plants and shallow-rooted plants, and combining trees, shrubs, and grasses.

[0026] Further, the DEM data downloaded in 2) of S1 is combined, specifically: loading each DEM data in ArcGIS software, splicing raster images through "ArcToolbox-Datamanagement tools-raster-mosaic" to obtain the whole DEM data.

[0027] Further, the river vector data obtained through hydrological analysis in 3) of S1 is as follows: the drainage basin map and the water system map of the evaluation area are obtained by using the hydrological analysis module of ArcGIS software. The analysis steps of the hydrological analysis module include depression filling processing, flow direction analysis, flow data analysis, raster calculator, and raster river network vectorization.

[0028] Further, 4) of S1 also includes converting the kml file into a kml file through "ArcToolbox-Conversion Tools-to KML" in the toolbox, and importing it into Google earth software.

[0029] Further, 5) of S1 utilizes satellite image to correct the vector data of the evaluation river, specifically: the corrected kml file is converted into a shp file by ET Geo Wizards tool set, imported into ArcGIS, and the final water system map of the evaluation river is obtained.

[0030] Further, the segment distance in S2 can be customized.

[0031] Further, the 1) river habitat quality evaluation in S3 specifically includes river channel morphology, flow state, bottom type, bank slope condition, vegetation structure, land use condition, deep pool-shoal sequence, artificial structure and the like, and there are 10 index layers and 82 evaluation indexes.

[0032] Further, the 2) river habitat degradation index evaluation system in S3 specifically includes artificial reinforcement of river bank and river bed, river bank flattening (artificial step formation or artificial embankment of river bank), river channel excavation, dam, river dike, bridge and the like, and there are 5 index layers and 28 evaluation indexes.

[0033] Further, theoretically, the higher the river habitat quality score of a river section, the lower the degradation index, and there is a negative correlation relationship, so the river habitat degradation index (HMS) can be used as a verification of the river habitat quality evaluation system.

[0034] Further, the river habitat evaluation result input and ArcGIS system management module are further included, and specifically, the river section numbers in the evaluation results S2 of various rivers are arranged, and the river habitat quality score, river habitat degradation index score and grade evaluation result are combined into the attribute table of the segmented river vector data in ArcGIS according to the field attribute.

[0035] The beneficial effects of the present application are as follows:

[0036] The evaluation system provided by the present application is intuitive and easy to understand, and has professional and operable properties, can quickly evaluate and long-term manage the investigated river or river section, better supports the river ecological protection practice of the Yangtze River and the like key river basin, has good ecological benefits, and is beneficial to large-scale popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The flowchart of the present application is shown in the figure;

[0038] Figure 2 The geographical location map of the river evaluated in the embodiment is shown in the figure;

[0039] Figure 3 The river habitat quality evaluation system (HQA) and index score are shown in the figure;

[0040] Figure 4 The river habitat degradation evaluation system (HMS) and index score are shown in the figure;

[0041] Figure 5 The grade classification map of the ArcGIS river habitat quality evaluation result is shown in the figure;

[0042] Figure 6 The river habitat quality evaluation result of the main tributaries of the upper reaches of the Yangtze River displayed by ArcGIS is shown in the figure. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0044] The problem is in the water, and the root is on the shore. In view of the fact that the current river quality assessment in China mainly relies on the control section water quality parameter judgment, which cannot objectively reflect and analyze the causes and influencing factors of river section quality degradation, the present application aims to build a river habitat status database, carry out river habitat quality assessment, and establish a habitat quality assessment system and management system suitable for the characteristics of rivers in China.

[0045] Embodiment

[0046] According to the management system and management method of the present application, the main tributaries of the upper reaches of the Yangtze River are selected for river habitat quality assessment and management.

[0047] As shown in Figures 1-6 A river physical habitat evaluation system based on ArcGIS and RHS includes:

[0048] I. Obtain river vector data module. Adopt national basic geographic information database own water system data (generally to 5 level river) or according to digital elevation model (Digital Elevation Model, in short DEM) analysis extraction. If the national basic geographic information database has the river vector data of the evaluation region, then directly carry out kml file conversion and rectification. If not, 1) according to the latitude and longitude range, download the DEM data of the evaluation region. In this embodiment, the latitude and longitude range of the evaluation region is 24.5°-29.5°N, 100.5°-106.5°E, a total of 30. 2) Merge the downloaded DEM data. The specific operation is: load each DEM data in ArcGIS, splice the raster image through "ArcToolbox-Datamanagement tools-raster-mosaic", and get the whole DEM data. 3) Obtain river vector data by hydrological analysis. Use the hydrological analysis module of ArcGIS to obtain the watershed map and water system map of the evaluation region. The analysis steps include filling processing, flow direction analysis, flow data analysis, raster calculator, raster river network vectorization, and the specific operation can refer to "Chapter 11 Hydrological Analysis" in "ArcGIS geographic information system spatial analysis experiment tutorial" by Tang Guoan and Yang Xin (2012); 4) delete other sub-basins and water networks outside the evaluation water system and watershed through "Editor" in ArcGIS, generate the final river water system data, and convert it into kml file through "ArcToolbox-Conversion Tools-to KML" in toolbox, and import into Google earth software; 5) rectify the vector data of the evaluation river by using satellite image. The rectified kml file is converted into shp file by ET Geo Wizards tool set, imported into ArcGIS, and the final water system map of the evaluation river is obtained. The rivers of this embodiment include Longchuan River, Yanju River, Heishui River, Pudu River, Niulan River, Xixi River, Xining River and Chishui River in the upper reaches of Yangtze River.

[0049] II. River vector data segmentation and numbering module. Use the Edit tool of ArcGIS software to segment the river. The segmentation distance can be customized according to the needs, such as 1km or 2km. In this embodiment, the segmentation is processed according to 2km, and 931 river segments are obtained in total for 8 rivers. The segmented vector data of each river is numbered in order from upstream to downstream, such as the first river segment at the source is numbered "1".

[0050] III. Habitat Quality Assessment Module. According to the River Habitat Survey (RHS) specification, the river in the embodiment is investigated in the field, and the investigation includes two aspects: 1) Habitat Quality Assessment (HQA). The system includes river morphology, flow regime, substrate type, bank condition, vegetation structure, land use condition, deep pool-shoal sequence, artificial structure, etc. There are 10 index layers and 82 evaluation indexes. 2) Habitat Modification Score (HMS). The system includes artificial reinforcement of river bank and riverbed, river bank flattening (artificial step or artificial embankment of river bank), river excavation, dam, river embankment, bridge, etc. There are 5 index layers and 28 evaluation indexes. In theory, the higher the river habitat quality score of a river section, the lower the degradation index, and the negative correlation exists between them. Therefore, the HMS value of the river can be used as a verification of the HQA evaluation system.

[0051] IV. River Habitat Quality Assessment and Grade Division Module. According to the field survey data and satellite picture data (for inaccessible areas), the score of each river section is evaluated, and the cumulative score of each index is the total score of the river section. The total score of each river section ranges from 3 to 43. The K-means clustering method is used to divide the river section scores into five grades, i.e. excellent, good, medium, poor and extremely poor, and the division standards of each grade are determined. In this embodiment, the score value greater than or equal to 34 is "excellent", the value between 26.5 and 33.5 is "good", the value between 20.5 and 26 is "medium", the value between 13.5 and 22 is "poor", and the value less than 13 is "extremely poor". Taking the Chishui River as an example, the HQA score of the Chishui River ranges from 7.0 to 43.0. According to the river habitat quality grading standards, in the Chishui River, 37.2% of the river sections have excellent habitat quality, with a total length of 163.7 km, mainly distributed in the upper reaches from Dagan Town to Shuiliao Township in the gorge section (Jiming Sanxiang) and the river section from Mati Township to Shuikou Town; 21.6% of the river sections have good habitat quality, with a total length of 95.0 km; 20.4% of the river sections have medium habitat quality, with a total length of 89.8 km; 18.6% of the river sections have poor habitat quality, with a total length of 81.8 km; and 2.2% of the river sections have extremely poor habitat quality, with a total length of 9.5 km. The HMS evaluation results show that the HMS of the Chishui River ranges from 0 to 18.0, and the main habitat degradation type is the reinforcement of the top of the river bank, followed by the water contact engineering in the middle and lower reaches, such as channel dikes, etc. Spatially, the HMS score of the headwater area and the river section from Maotai to Chishui City in the middle reaches of the Chishui River is higher. Regression analysis shows that there is a significant negative correlation between the HQA and HMS of the Chishui River, indicating that the stronger the disturbance, the worse the river habitat quality (R2 = 0.46).

[0052] Five. River habitat quality restoration strategy

[0053] According to the evaluation results of Chishui River, habitat restoration strategies for different reaches of the river are proposed. In the reaches of Zhenxiong section, the river channel is generally canalized, and the vegetation in the riparian zone is mainly farmland with little natural vegetation. It is suggested to ecologically transform the bank slope and riparian zone of the above-mentioned reaches, replace the existing concrete bank slope with an ecological net and stone cage combination slope protection, and according to the local plant composition, supplement the vegetation of the riparian zone with little vegetation in the reaches to restore the diversity and coverage of vegetation. In the reaches below Chishui City, there are many dikes or locks (closed water areas formed by dikes). It is suggested to ecologically transform the concrete dikes, replace them with steel wire stone cage dam bodies to increase the permeability of the dikes, which is beneficial to the attachment, habitat and diversity restoration of algae and benthic animals. The hydraulic connection of the closed water area is restored by removing part of the dam body of the lock, opening the dam body or burying a culvert, etc. to promote the transverse exchange of fish.

[0054] Six. River habitat evaluation result input module and ArcGIS system management module. Arrange the evaluation results of each river (excel table) according to the aforementioned reach number, and merge the HQA score, HMS score and grade evaluation results into the attribute table of the segmented river vector data in ArcGIS according to the field attribute. The specific operation steps are: right-click on the segmented river vector data - Joins and Relates - Join - select Join attributes from a table - choose the field in this layer that join will be based on - select the loaded excel data table. After merging the field attributes, click Save. Right-click on Properties in the Symbology page of the attribute dialog box. Select "unique values" in "Categories" to manage and display the data using the habitat quality grades of each reach.

[0055] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A river physical habitat assessment system based on ArcGIS and RHS, characterized in that, Comprise: S1. Obtain river vector data module using national basic geographic information database has its own water system data or according to digital elevation model analysis extraction surveyed river vector data; Specifically, the national basic geographic information database has the river vector data of the evaluation area, then directly kml file conversion and rectification is carried out; If not, 1) download DEM data of the evaluation area according to latitude and longitude range; 2) merge the downloaded DEM data; 3) hydrological analysis obtains river vector data; 4) through "Editor" in ArcGIS, delete other sub-basins and water network outside the evaluation water system and basin, generate the final river system data; 5) utilize satellite image to rectify the vector data of the evaluation river; S2. River vector data segmentation and numbering module uses Edit editing tool of ArcGIS software to segment the surveyed river, and the segmented vector data of each surveyed river is numbered in order from upstream to downstream; S3. River habitat quality status segmentation investigation module carries out field investigation on the surveyed river according to the relevant specifications of river habitat investigation, and the investigation content includes two aspects: 1) river habitat quality evaluation; 2) river habitat degradation index evaluation system; S4. River habitat quality evaluation and grade division module evaluates each river section according to the field investigation data and satellite image data, and the cumulative score of each index is the total score of the river section. In theory, the total score of each river section ranges from 0 to 53. The river section score is graded by using K-means clustering method, and the division standard of each grade is determined. The grade division standard of river habitat quality is: the score value is greater than or equal to 34, which is "excellent"; between 26.5 and 33.5, which is "good"; between 20.5 and 26, which is "medium"; between 13.5 and 22, which is "poor"; and lower than 13, which is "very poor"; S5. River habitat quality restoration module determines the corresponding restoration countermeasures of the surveyed river section according to the difference degree of each score and the highest value: when the surveyed river section is an erosion river bank, the score is only 0.5, then the degraded river bank needs to be restored, and aquatic plants are planted and appropriate size of stone blocks are accumulated to consolidate the river bank; the surveyed river section has no vegetation coverage, and the score is 0, then the native plant needs to be supplemented according to the surrounding vegetation type, and the vegetation restoration type of the near-water river bank mainly includes various aquatic vascular plants; the vegetation restoration of the land buffer zone considers the mixed growth of evergreen and deciduous tree species, the combination of deep-rooted and shallow-rooted plants, and the combination of trees, shrubs and grasses; S1 5) utilize satellite image to rectify the vector data of the evaluation river, specifically, the rectified kml file is converted into shp file by ETGeoWizards tool set, imported into ArcGIS, and the final water system map of the evaluation river is obtained; S3 1) river habitat quality evaluation, specifically including river channel morphology, flow state, bottom type, bank slope condition, vegetation structure, land use condition, deep pool-shoal sequence and artificial structure evaluation content; S3 2) River habitat degradation index evaluation system, including the evaluation content of river bank, river bed artificial reinforcement, river bank flattening, river excavation, dam, river embankment, bridge; In theory, the higher the river habitat quality score of a river section, the lower the degradation index, showing a negative correlation, so the river habitat degradation index is used as a verification of the evaluation of river habitat quality; It also includes river habitat evaluation result input and ArcGIS system management module, which is to arrange the river section number in the evaluation result S2, and combine the river habitat quality score, river habitat degradation index score and grade evaluation result into the attribute table of the segmented river vector data in ArcGIS according to the field attribute.

2. The ArcGIS and RHS based river physical habitat assessment system according to claim 1, wherein, S1 2) Merging downloaded DEM data, which is to load each DEM data in ArcGIS software, and mosaic the raster image through "ArcToolbox-Data management tools-raster-mosaic" to get the whole DEM data.

3. The ArcGIS and RHS based river physical habitat assessment system according to claim 1, wherein, S1 3) Hydrological analysis to obtain river vector data, which is to use the hydrological analysis module of ArcGIS software to obtain the watershed map and river system map of the evaluation area. The analysis steps of the hydrological analysis module include depression filling processing, flow direction analysis, flow data analysis, raster calculator and raster river network vectorization.

4. The ArcGIS and RHS based river physical habitat assessment system according to claim 1, wherein, S1 4) It also includes, and is converted into a kml file through "ArcToolbox-Conversion Tools-to KML" in the toolbox, and is imported into Google earth software.

5. The ArcGIS and RHS based river physical habitat assessment system according to claim 1, wherein, S2 The segmentation distance is customized.

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