A water system sampling method of multi-parameter synchronous recording

Abstract

This invention relates to the fields of environmental monitoring and geological survey technology, specifically to a multi-parameter synchronous recording method for river system sampling. It is applicable to scenarios requiring precise control of sampling point locations and synchronous recording of multi-dimensional parameters, such as river sediment sampling and hydrological environmental surveys. The method includes pre-sampling preparation, navigation and positioning, on-site adjustment and marking, and synchronous recording of multiple parameters. Through the collaborative operation of topographic map annotation, contour line analysis, and waterline extraction, combined with a catchment area ≤0.25 km² control standard, it ensures the rationality and comprehensive coverage of sampling point layout, avoids redundant control or control gaps, and improves sampling representativeness. Through on-site river system verification and point optimization, it can promptly identify and supplement unmarked river system sampling points, while ensuring that sampling points are located in the optimal catchment area and avoid interference sources. Through synchronous recording of multiple parameters, it completely preserves key information such as the coordinates, topography, and medium of the sampling points, providing comprehensive basic data support for subsequent data processing and analysis.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring and geological survey technology, specifically to a multi-parameter synchronous recording method for water system sampling, applicable to scenarios such as water system sediment sampling and hydrological environmental surveys that require precise control of sampling points and synchronous recording of multi-dimensional parameters. Background Technology

[0002] In fields such as environmental monitoring and geological and mineral surveys, water system sampling is a crucial means of obtaining regional environmental and geological information. The accuracy of sampling points and the representativeness of the sampling data directly determine the reliability of subsequent analysis results. Existing water system sampling methods often employ a combination of single topographic map placement and simple positioning, which has the following drawbacks: First, the placement of points lacks scientific control over the catchment area, easily leading to overlapping or blank areas in the control range of sampling points, resulting in insufficient representativeness. Second, the positioning accuracy is not strictly controlled; relying solely on GPS navigation can easily result in significant errors, making it difficult to accurately reach the designed points. Third, the lack of dynamic verification and point optimization of the actual water system during on-site sampling easily leads to the omission of unmarked water systems or the influence of interference sources due to improper point selection. Fourth, incomplete and asynchronous parameter recording during the sampling process makes subsequent data tracing and analysis difficult.

[0003] Therefore, there is an urgent need for a sampling method that can achieve precise sampling, accurate positioning, dynamic optimization, and simultaneous recording of multiple parameters to solve the problems of low sampling efficiency, poor data reliability, and insufficient representativeness in existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a water system sampling method with multi-parameter synchronous recording. Through quantitative control of catchment area, dual-mode positioning and navigation, on-site water system verification and point optimization, and synchronous recording of multi-dimensional parameters, it achieves efficient, standardized and accurate sampling, solving the problems of insufficient representativeness, inaccurate positioning, incomplete recording and poor traceability of existing technologies.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for simultaneous recording of multiple parameters in a water system includes the following steps:

[0007] Step 1, pre-sampling preparation includes topographic map annotation, contour line watershed analysis, and extraction of dual waterlines from DEM and artificial data. Specifically:

[0008] Topographic map annotation: Select a 1:50,000 scale topographic map conforming to GB / T 12343.1-2008 standard and mark all water systems with a length exceeding 500m; refer to the "Regional Geochemical Survey Specification 1:250000" (DZ / T 0167-2022) to initially set up sampling points, with the spacing between adjacent points controlled at 500-800m;

[0009] Contour line drainage analysis: Contour line data is extracted using GIS software to determine the drainage basin range of each preliminary sampling point; the control drainage area is calculated to strictly ensure that the control drainage area of ​​a single sampling point is ≤0.25 km²; points exceeding the standard are finely adjusted along the water system (distance ≤300m) and re-verified to avoid overlapping drainage areas;

[0010] DEM and manual dual waterline extraction: The waterline was cross-validated by both automatic extraction of DEM data (D8 algorithm, threshold 0.1km²) and manual delineation; the waterline was superimposed on the initial sampling points, and the calibration points were ensured to be located at the mouth of the primary or secondary water system, with a deviation from the waterline not exceeding 50m.

[0011] The beneficial effects of adopting the above steps are as follows: By introducing the catchment area (≤0.25km²) as a constraint indicator and combining contour line analysis and waterline extraction technology, the blindness of traditional methods relying solely on experience in point placement is overcome, ensuring that the catchment area controlled by each sampling point is of uniform size, avoiding the element dilution effect caused by excessively large control areas or the local abnormal interference caused by excessively small areas, and significantly improving the uniformity and representativeness of sampling control; through the overlay analysis of GIS software, the problem of overlapping control ranges of sampling points or the appearance of sampling blank areas is effectively solved, ensuring full coverage and no omissions in the survey area; dual waterline verification improves the accuracy of water system sampling, ensuring that the points fall on the actual confluence path.

[0012] Step 2, Navigation and Positioning: Specifically, the design coordinates (WGS84) are imported into a mobile terminal equipped with GPS and BeiDou dual-mode positioning; the sampling personnel navigate to a 1km radius around the target area using map software; a portable high-precision GPS receiver is turned on for static calibration to obtain the actual coordinates and compare them with the design coordinates; if the planar error is greater than 2mm on the topographic map or greater than 100m on the ground, the direction of travel is adjusted until the error is ≤2mm or ≤100m, thus locking in the precise area.

[0013] The beneficial effects of adopting the above steps are: dual positioning cross-checking greatly improves navigation reliability, and the error threshold of ≤2mm on the topographic map or ≤100m on the ground is used as the standard for reaching the precise area, which solves the problem of unclear approximate location in traditional sampling and greatly reduces the blindness and time cost of finding points.

[0014] Step 3, on-site adjustments, including water system verification and site optimization, specifically:

[0015] Water system verification: Verify the actual water system within a 500m radius of the precise area; if an unmarked water system with a length >300m is found, additional sampling points are set up at its confluence or middle section, and its catchment area is controlled to be ≤0.25 km².

[0016] Site optimization: Use a compass and contour lines to determine the direction of water flow and locate the sampling point at the maximum water flow (such as the front edge of an alluvial fan or the inside of a river bend); measure and avoid sources of interference to ensure that the distance between the sampling point and residential areas is ≥300m, the distance from main roads is ≥200m, and the distance from rural roads is ≥50m; if these conditions are not met, make minor adjustments along the direction of water flow.

[0017] The beneficial effects of adopting the above steps are as follows: In response to the problem that topographic maps lag behind actual changes, the on-site water system verification and supplementary sampling mechanism can promptly discover and collect information on unmarked water systems, ensuring the accuracy of the data; by using a compass to determine the direction of water flow and a laser rangefinder to avoid interference sources (residential areas, roads), the sampling points are ensured to be located in the optimal position for material accumulation and far away from human pollution, thus eliminating interference data at the source and ensuring that the analysis results can truly reflect the regional background values ​​or abnormal characteristics.

[0018] Step 4, marking and multi-parameter synchronous recording, specifically:

[0019] Double physical marking was achieved using weather-resistant red paint and hanging red ribbons; a portable data logger was used to simultaneously record multi-dimensional parameters, including: sampling point number, precise GPS coordinates, sampling time, terrain features, sampling medium type and characteristics, type and distance of surrounding interference sources, marking method and location.

[0020] The beneficial effects of adopting the above steps are: the dual marking method of spray paint and red cloth strips improves the retention rate of sampling points and the identifiability of subsequent inspection and re-sampling; the portable recorder synchronously records multi-dimensional parameters such as media characteristics and distance to interference sources, avoiding omissions and errors, realizing full-process traceability, and solving the problems of information loss and traceability difficulties in traditional recording methods.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. By combining topographic map annotation, contour line analysis and waterline extraction, and in conjunction with the control standard of catchment area ≤ 0.25 km², we can ensure the rationality and comprehensiveness of sampling point layout, avoid duplicate control or control gaps, and improve the representativeness of sampling.

[0023] 2. By using GPS and mobile map for collaborative navigation and comparison, we strictly control planar errors to ensure that sampling personnel can reach the vicinity of the design points efficiently and accurately, reducing the time cost of finding the points;

[0024] 3. Through on-site water system verification and site optimization, sampling points for unmarked water systems can be identified and supplemented in a timely manner, while ensuring that sampling points are located in the optimal catchment area and avoid interference sources, thereby further ensuring the reliability of sampling data;

[0025] 4. Through multi-parameter synchronous recording, key information such as the coordinates, terrain, and medium of the sampling points are fully preserved, providing comprehensive basic data support for subsequent data processing and analysis;

[0026] 5. Clarify the operating standards and precautions for each step, and combine automated software with manual verification to avoid defects caused by mechanical operation and improve the standardization and repeatability of the sampling process. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] A method for simultaneous recording of multiple parameters in a water system includes the following steps:

[0029] Step 1: Preparations before sampling

[0030] 1.1 Topographic Map Annotation: Select a 1:50,000 scale topographic map with an accuracy conforming to GB / T 12343.1-2008 standard. Use professional drawing tools (such as tracing paper and drawing pens) to annotate all water systems (including rivers, streams, and seasonal gullies) with a length exceeding 500m on the topographic map. The annotation should include the name of the water system (if any), the coordinates of the starting and ending points, and the direction. Refer to the requirements for water system sediment sampling point layout in the "Regional Geochemical Survey Specification 1:250000" (DZ / T 0167-2022) to initially set up sampling points. The distance between adjacent preliminary sampling points should be controlled at 500-800m to ensure that the sampling points initially cover all major water system confluence nodes.

[0031] 1.2 Contour Line Analysis: Contour line interpretation was used in conjunction with GIS software (such as ArcGIS 10.8) to extract contour line data with a contour interval of 10m from the topographic map. The hydrological analysis module of the software was used to determine the catchment area corresponding to each preliminary sampling point. The software was used to calculate the control catchment area of ​​each preliminary sampling point, strictly ensuring that the control catchment area of ​​a single sampling point is ≤0.25 km². For sampling points whose calculated control area exceeds the standard, the point positions were fine-tuned along the upstream and downstream direction of the river system, with the fine-tuning distance not exceeding 300m. After fine-tuning, the catchment area needs to be re-verified to avoid overlapping control of catchment areas with adjacent sampling points.

[0032] 1.3 Waterline Extraction: Waterlines shall be extracted using one of the following two methods, and the results of the two methods shall be cross-validated;

[0033] Method 1: Using DEM (Digital Elevation Model) data with a resolution of ≥30m, the minimum catchment area threshold is set to 0.1 km² using the Hydrology toolset in ArcGIS software, and the D8 algorithm is used to automatically extract the water system network.

[0034] Method 2: Use manual drawing on topographic maps to draw water lines along the center line of the water system. The accuracy requirement is that the distance between two adjacent points is ≤50m.

[0035] After extracting the waterline, the waterline data is superimposed and compared with the coordinates of the initially deployed sampling points to calibrate the initial sampling point positions and ensure that all sampling points are accurately located at the primary water system inlet (where tributaries flow into the main stream), the secondary water system inlet (where tributaries flow into tributaries), or the confluence of the end of the main stream, with a distance from the waterline not exceeding 50m.

[0036] Step 2: Navigation and Positioning

[0037] Export the design coordinates of each sampling point determined in step 1 (using the WGS84 coordinate system, with accuracy retained to 6 decimal places) as a KML format file, and import it into a smartphone with the latest version of the Aowei Interactive Map application installed (requiring GPS + Beidou dual-mode positioning function); the sampling personnel set off with the mobile phone and a portable GPS receiver (positioning accuracy ≤ 5m), and use the "Navigate to Point" function of Aowei Map to select the "Walking Navigation" mode to go to the target sampling area; after arriving within 1km of the target area, turn on the portable GPS receiver, let it stand still for 3 minutes to complete the positioning calibration, obtain the actual positioning coordinates, compare the coordinates with the design coordinates in Aowei Map, and calculate the plane error; if the plane error is > 2mm on the topographic map (corresponding to an actual distance > 100m), recheck the navigation path, adjust the direction of travel until the plane error is ≤ 2mm, and confirm that you have reached the accurate area around the design point.

[0038] Step 3: On-site adjustments

[0039] 3.1 Water System Verification: After arriving at the precise area determined in step 2, carry a handheld laser rangefinder (measurement accuracy ±1cm) and a hand-drawn map (printed with the design points and surrounding terrain). Check the actual water system distribution within a 500m radius of the precise area and compare it with the water systems marked on the topographic map one by one. Focus on checking for any unmarked water systems. For any suspected unmarked water systems, use a laser rangefinder to measure their length. If the actual length is >300m, additional sampling points need to be set up at the confluence or middle section of the water system. The control catchment area of ​​the additional sampling points should still be ≤0.25 km². Use a drawing pen to mark the location of the additional sampling points and the direction of the water system on the hand-drawn map, and indicate the reason for the addition and the length of the water system.

[0040] 3.2 Site Optimization: Carry a compass (accuracy ±0.5°) and a topographic map. Use the compass and contour lines to determine the water flow direction, ensuring that the sampling point is located at the end of the water flow direction (the maximum water flow point). Prioritize the selection of the front edge of the alluvial fan at the mouth of the gully, the inside of the river bend, or the alluvial rich area (with a sediment thickness ≥20cm observed visually) as the final sampling point. At the same time, use a laser rangefinder to measure the distance between the sampling point and surrounding interference sources, ensuring that the distance to residential areas is ≥300m, the distance to main roads (national highways, provincial highways, county roads) is ≥200m, and the distance to rural roads is ≥50m. If the distance does not meet the requirements, the sampling point must be slightly adjusted upstream or downstream along the water flow direction until the distance requirements are met and the sampling point is still located at the maximum water flow point.

[0041] Step 4: Marking and Multi-parameter Synchronization Recording

[0042] Use weather-resistant red paint (adhesion ≥2, water resistance ≥48h) to spray circular marking symbols with a diameter ≥20cm on rocks or fixed objects within 1m around the sampling point. At the same time, hang red cloth strips (30cm×50cm) with the sampling point number printed on them on nearby tree branches (1.5-2m high) for double marking.

[0043] A portable data logger (equipped with GPS positioning, data storage, and offline editing functions) was used to synchronously record multi-dimensional parameters, including: sampling point number, precise GPS coordinates (WGS84 coordinate system, retaining 6 decimal places), sampling time (accurate to the minute), terrain features (catchment type, slope, surrounding landforms), sampling medium type and characteristics (e.g., silt: grayish-black, good plasticity; fine sand: particle size 0.1-0.25mm, good sorting ability), surrounding interference source type and distance, marking method and location.

[0044] Furthermore, during the sampling point layout process in step 1, if automatic point layout software (such as ArcGIS 10.8) is used for auxiliary point layout, the software point layout parameters need to be set (minimum catchment area 0.1-0.25 km², distance between adjacent points 500-800m). After the point layout is completed, organize more than two professional technicians to conduct manual verification, and randomly sample 30% of the sampling points to recalculate their controlled catchment area to ensure that the error is ≤5% and avoid uneven catchment area controlled by each sampling point due to mechanical point layout.

[0045] When setting up sampling points, the survey area is divided into 1km×1km grids. The sampling points are projected into the grids, and the distribution of sampling points is checked grid by grid to ensure that there are no three consecutive blank grid areas between adjacent sampling points. If blank grids appear, sampling points need to be added at the water system nodes within the blank grids.

[0046] Example

[0047] This embodiment takes a river system sediment sampling survey in a certain area as an example, and uses the multi-parameter synchronous recording river system sampling method of the present invention. The specific steps are as follows:

[0048] Step 1: Preparations before sampling

[0049] 1.1 Topographic Map Annotation: A 1:50,000 topographic map (compliant with GB / T 12343.1-2008 standard, contour interval 10m) of the survey area (118°XX′XX″-118°XX′XX″E, 32°XX′XX″-32°XX′XX″N) was selected. Two professional draftsmen were organized to use tracing paper and a 0.5mm drafting pen to annotate all water systems with a length exceeding 500m on the topographic map, including 3 rivers, 8 streams, and 5 seasonal gullies. Referring to the "Regional Geochemical Survey Specification 1:250000" (DZ / T 0167-2022), 32 sampling points were initially set up, with the distance between adjacent sampling points controlled at 600-700m to ensure preliminary coverage of all major water system confluence nodes.

[0050] 1.2 Contour Analysis: Contour data was extracted from the topographic map using ArcGIS 10.8 software. Watershed analysis was performed using the Hydrology toolset to calculate the control catchment area of ​​32 preliminary sampling points. The calculations showed that the control catchment area of ​​four sampling points exceeded the limit (0.32 km², 0.28 km², 0.30 km², and 0.27 km², respectively). The points were slightly adjusted along the upstream and downstream directions of the water system, with adjustment distances of 150m, 220m, 180m, and 250m, respectively. After recalculation, the catchment area of ​​each point was ≤0.25 km², and there was no overlap in the catchment areas of adjacent sampling points.

[0051] 1.3 Waterline Extraction: The survey area had DEM data with a resolution of 30m. Using the Hydrology toolset of ArcGIS 10.8 software, with a minimum catchment area threshold of 0.1 km², the water network was automatically extracted using the D8 algorithm. At the same time, a technician manually delineated the waterlines for cross-validation. The overlap of the extracted waterlines reached 92%. The water network was overlaid and compared with the preliminary sampling points. It was found that the distances of the three preliminary sampling points from the waterline were 65m, 72m, and 80m, respectively. After adjustment, they were all located near the waterline, and the distances from the waterline were ≤30m.

[0052] 2. Navigation and Positioning

[0053] The calibrated design coordinates (WGS84 coordinate system) of the 32 sampling points were exported as KML format and imported into a Huawei Mate 50 Pro phone (with GPS + Beidou dual-mode positioning) with AVC Interactive Map version 9.5.8 installed. The sampling personnel set off with the phone and a Trimble R2 portable GPS receiver (positioning accuracy ±3m) and went to the first target sampling area through the "walking navigation" mode of AVC Map. After reaching a range of 1km around the target area, the Trimble R2 GPS receiver was turned on and left to stand still for 3 minutes to complete the positioning calibration and obtain the actual coordinates (118°XX′XX.XXXXXX″E, 32°XX′XX.XXXXXX″N). The coordinates were compared with the design coordinates in AVC Map and the plane error was calculated to be 1.5mm (corresponding to 75m on the ground), which met the error control requirements and confirmed that the accurate area had been reached.

[0054] 3. On-site adjustments

[0055] 3.1 Water System Verification: Carrying a Bosch GLM 500 handheld laser rangefinder and a hand-drawn map printed with the design points, the water system was checked within a 500m radius of the precise area. A stream not marked on the topographic map was found. Its length was measured to be 420m using the laser rangefinder, which met the supplementary sampling criteria. One additional sampling point was set up at the confluence of the stream, and its controlled catchment area was calculated to be 0.22 km². The location of the supplementary sampling point and the direction of the stream were plotted on the hand-drawn map with a drawing pen, and the following was noted: "Reason for supplementation: Water system not marked, length 420m".

[0056] 3.2 Site Optimization: Using a geological compass (accuracy ±0.5°), the water flow direction was determined to be from northwest to southeast by combining the compass with contour lines. The original design site was located in the middle of the stream. It was adjusted to the southeast facing the front edge of the alluvial fan at the mouth of the stream (the point of maximum water flow). The adjusted site was measured with a laser rangefinder and found to be only 50m away from the main rural road, which did not meet the distance requirement for interference sources. It was then finely adjusted again by 120m along the flow direction. After the adjustment, the distance from the main rural road was 170m, and it was still located in the alluvial rich area (sediment thickness of about 35cm). This site was determined as the final sampling point.

[0057] 4. Tagging and multi-parameter synchronous recording

[0058] A 25cm diameter circular marker was sprayed onto rocks 1m away from the sampling point using weather-resistant red paint. A red cloth strip (30cm×50cm) printed with "Sampling Point 001" was hung on a tree branch 2m high nearby. Parameters were recorded simultaneously using a Southern Surveying and Mapping S760 portable data logger: sampling point number 001, precise GPS coordinates (118°XX′XX.XXXXXX″E, 32°XX′XX.XXXXXX″N), sampling time 202X year XX month XX day XX:XX, terrain features (alluvial fan at the confluence of a secondary water system, slope 5°, surrounded by low hills), sampling medium (silt, grayish-black, good plasticity, containing a small amount of plant debris), surrounding interference sources (rural road, 170m away), and marking method (rock paint + red cloth strip on tree branch).

[0059] Throughout the sampling process, the following precautions were strictly followed: When using ArcGIS 10.8 software to assist in the sampling point layout, the minimum catchment area was set to 0.15 km² and the distance between adjacent points was set to 650m. After the sampling points were laid out, 10 sampling points (30%) were randomly selected and the catchment area was recalculated, with an error of ≤3%. The survey area was divided into 1km×1km grids, and the distribution of sampling points was checked grid by grid. Two consecutive blank grid areas were found. One sampling point was added at each water system node in the blank grid to ensure that there were no three consecutive blank grids.

[0060] Using the sampling method described in this embodiment, sampling was completed at 35 sampling points (including 3 supplementary sampling points) in a certain project. All sampling points were accurately located in the optimal catchment area, and the distances from interference sources met the requirements. The sampling data was 100% complete, including 12 parameters such as number, coordinates, time, topography, and medium. Subsequent heavy metal content analysis of the sampled sediments showed that the coefficient of variation was ≤15%, which accurately reflects the distribution characteristics of heavy metals in the aquatic environment of the surveyed area, verifying the reliability and practicality of this method.

[0061] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for water system sampling with multi-parameter synchronous recording, characterized in that, Includes the following steps: Step 1: Preparations before sampling Select a topographic map that meets the standards, mark the water system, and initially set up sampling points; Using GIS software to extract contour data, the catchment area of ​​each preliminary sampling point was determined, and the control catchment area of ​​a single sampling point was calculated and controlled to be ≤0.25 km². Sampling points with excessive control area were fine-tuned along the water system. The waterline was extracted by cross-validation using both automatic DEM data extraction and manual delineation. The waterline was then overlaid and compared with the initial sampling points to calibrate the position of the initial sampling points and ensure that the sampling points were located at the confluence nodes of the water system and that the distance from the waterline did not exceed 50m. Step 2: Navigation and Positioning The calibrated sampling point design coordinates are imported into the mobile terminal, and the sampling personnel carry the mobile terminal and portable GPS receiver to the target area. Once within 1km of the target area, turn on the portable GPS receiver to obtain the actual location coordinates, compare these coordinates with the design coordinates in the mobile terminal, calculate the plane error, adjust the direction of travel until the plane error meets the preset threshold, and confirm that you have reached the precise area. Step 3: On-site adjustments Check the actual water system distribution around the precise area. If an unmarked water system is found and its length exceeds the preset value, additional sampling points will be set up. Using a compass and terrain to determine the direction of water flow, the sampling point was located at the point of maximum water flow. If the distance between the measurement sampling point and the surrounding interference source does not meet the preset avoidance distance requirement, the point position is finely adjusted along the water flow direction until the requirement is met. Step 4: Marking and Multi-parameter Synchronization Recording The finalized sampling points are physically marked; Use a portable data logger to synchronously record the sampling point number, precise GPS coordinates, sampling time, terrain features, sampling medium type and characteristics, type and distance of surrounding interference sources, marking method and location.

2. The method according to claim 1, wherein, In step 1, when initially setting up sampling points, the distance between adjacent initial sampling points is controlled at 500-800m; the controlled catchment area is ≤0.25km². If the controlled catchment area of ​​the initial sampling point exceeds the standard, the point position is finely adjusted along the upstream and downstream direction of the water system. The fine adjustment distance shall not exceed 300m, and the catchment range needs to be re-checked after the fine adjustment to avoid overlap with the catchment area of ​​adjacent sampling points.

3. The method according to claim 1, wherein, In step 1, the method of cross-validating the extraction of waterlines using both automatic DEM data extraction and manual delineation specifically includes: Using DEM data with a resolution of ≥30m, the minimum catchment area threshold was set to 0.1km² using the Hydrology toolset of GIS software, and the D8 algorithm was used to automatically extract the water system network. Meanwhile, on the topographic map, a manual drawing method is used to draw the water line along the center line of the water system, and the drawing accuracy requires that the distance between two adjacent points be ≤50m; The waterline data extracted by the two methods are superimposed and compared with the coordinates of the initially deployed sampling points to ensure that all sampling points are accurately located at the confluence of primary water system outlets, secondary water system outlets, or the end of dry ditches.

4. The method according to claim 1, wherein, In step 2, the mobile terminal is equipped with a map application that has GPS + Beidou dual-mode positioning function; the positioning accuracy of the portable GPS receiver is ≤5m; the preset threshold is 2mm on the topographic map or 100m in the actual distance. If the planar error is greater than the preset threshold, the navigation path will be rechecked until the planar error is less than or equal to the preset threshold.

5. The method according to claim 1, wherein, In step 3, the verification of the actual water system distribution specifically involves: carrying a handheld laser rangefinder and a hand-drawn map, and verifying within a 500m radius of the precise area; for any suspected unmarked water systems found, measuring their length with a laser rangefinder; if the actual length is greater than 300m, additional sampling points need to be set up at the confluence or middle section of the water system, and the control catchment area of ​​the additional sampling points still needs to be ≤0.25km².

6. The method according to claim 1, wherein, In step 3, the distance between the measurement sampling point and the surrounding interference source specifically includes: selecting the leading edge of the alluvial fan at the mouth of the ditch, the inner side of the river bend, or the alluvial-rich area as the final sampling point; Use a laser rangefinder to measure the distance between the sampling point and surrounding interference sources, ensuring that the distance to residential areas is ≥300m, the distance to main roads is ≥200m, and the distance to rural roads is ≥50m. If the distance does not meet the requirements, fine-tune the location of the sampling point along the direction of water flow, and after fine-tuning, it must still be located at the maximum water flow point.

7. The method according to claim 1, wherein, In step 4, the physical marking adopts a dual marking method: a circular marking symbol with a diameter of ≥20cm is sprayed on rocks or fixed objects within a 1m radius of the sampling point using weather-resistant red paint, and at the same time, a red cloth strip printed with the sampling point number is hung on nearby tree branches for auxiliary marking.

8. The method for simultaneous recording of multiple parameters in a water system according to claim 1, characterized in that, The method also includes a grid-based verification step: the survey area is divided into 1km×1km grids, sampling points are projected onto the grids, and the distribution of sampling points is verified grid by grid to ensure that there are no three consecutive blank grid areas between adjacent sampling points; if three consecutive blank grid areas appear, sampling points need to be added at the water system nodes within the blank grids.