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Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Water Level Observation Standard
GBJ138—90
1991Beijing
Engineering Construction Standard Full-text Information System
W Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Water Level Observation Standard
GBJ138—90
Editor Department: Ministry of Water Resources of the People's Republic of ChinaApproval Department: Ministry of Construction of the People's Republic of ChinaImplementation Date: 1991 June 1st
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Notice on the Release of the National Standard "Water Level Observation Standard"
(90) Jianbiaozi No. 318
According to the requirements of the State Planning Commission's Document No. [1986] 250, the "Water Level Observation Standard" jointly formulated by the former Ministry of Water Resources and Electric Power and relevant departments has been reviewed by relevant departments and is now approved as the "Water Level Observation Standard" GBJ138-90 as a national standard to be implemented on June 1, 1991.
This standard is managed by the Ministry of Water Resources. The specific interpretation and other work is the responsibility of the Hydrological Bureau of the Yangtze River Water Resources Commission of the Ministry of Water Resources. The publication and distribution is organized by the Standard and Quota Research Institute of the Ministry of Construction.
Ministry of Construction of the People's Republic of China
July 2, 1990
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Preparation Instructions
This standard is compiled by the Hydrological Bureau of the Yangtze River Water Conservancy Commission of the Ministry of Water Resources in accordance with the requirements of the State Planning Commission's Document No. 250 (1986), and is jointly compiled with relevant units.
In the process of compiling this standard, the standard compilation team conducted extensive investigations and studies, carefully summarized the practical experience of hydrological work in my country for decades, referred to relevant international standards and advanced foreign standards, carried out scientific research and experimental verification work on major technical issues, and widely solicited opinions from relevant units across the country. Finally, our ministry and relevant departments reviewed and finalized the draft.
Since this standard is compiled for the first time, during the implementation process, we hope that all units will combine engineering practice and scientific research, carefully summarize experience, and pay attention to accumulating information. If you find that there is a need for modification and enrichment, please send your opinions and relevant information to the Hydrology Bureau of the Yangtze River Water Conservancy Commission of the Ministry of Water Resources (No. 1155, Jiefang Avenue, Wuhan City) for reference in future modifications. Ministry of Water ResourcesWww.bzxZ.net
May 1990
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Chapter 1 General
Chapter 2 Water Level Station
Section 1 Site Selection of Water Level Station
Section 2 Determination of Base Surface
Section 3 Setting of Level Points
Section 4 Layout of Water Level Sections
Section 5 Topographic Survey and Large Section Survey of Water Level StationsSection 6 Verification of Survey Stations
Chapter 3 Water Level Observation Equipment
Section 1 Water
Section 2
Stylus and Pendulum Water Level Gauges
Section 3
Section 4
Chapter 4
Self-recording Water Level Gauges….||tt| |Error sources and control of setting and installation****Water level observation using water gauge
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
General provisions
Water level observation at river stations·
Water level observation at reservoirs, lakes and weir stationsTidal level observation
Low water level observation
High and flood level observation
Water level comparison measurement when relocating the basic water gauge sectionSection 7
Section 8 Observation of ancillary items
Section 9 Water level correction method when the zero point elevation of the water gauge changes, Section 10 Error sources and control of manual readingChapter 5 Water level observation using self-recording water level gaugeSection 1 Inspection and use of self-recording water level gauge Engineering Construction Standard Full Text Information System
China Electric Power
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Section 2 Comparison of Self-recording Water Level Gauges
Section 3 Correction and Extraction of Self-recording Water Level Records Section 4 Sources and Control of Errors in Self-recording Records Chapter 6 Calculation of Water Level Observation Results.
Section 1
Calculation of Daily Average Water Level
Section 2
Calculation of Water Surface Gradient...
Section 3
Statistics of Tidal Level Characteristic Values
Chapter 7 Uncertainty of Water Level Observation Appendix 1 of Estimation
Appendix 2
Appendix 3
Regulations for the preparation of reports
Conversion of the opening height of radial gates
Explanation of terms used in this standard
Additional notes
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Engineering Construction Standard Full-text Information System
Chapter 1 General
Article 1.0.1 This standard is formulated in order to reasonably unify the technical regulations on the establishment of water level stations, the setting of water level observation equipment, water level observation and calculation in my country, ensure the quality of water level observation data, and provide a reliable basis for various types of engineering construction. Article 1.0.2 This standard applies to water level observations in natural rivers, lakes, reservoirs, artificial canals, river sections affected by tides and near water projects. Article 1.0.3 The time system for water level observations shall adopt Beijing Standard Time. Article 1.0.4 In addition to implementing this standard, water level observations shall also comply with relevant national standards in force.
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·1
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Chapter 2 Water Level Station
Section 1 Site Selection of Water Level Station
Article 2.1.1 The site selection of water level stations shall meet the purpose of station construction and the requirements of observation accuracy, and shall be selected at locations that are convenient for observation and close to towns or settlements, and shall comply with the following provisions:
, River water level stations should be selected in river sections with straight river channels, stable riverbeds and concentrated water flows.
2. The lake outlet water level station should be located above the outflow section where the water flow is stable. The weir water level station and the water level station in the lake and reservoir should be located at a location with stable bank slope and representative water level.
3. The estuary tidal water level station should be located at a location with a flat riverbed, not prone to erosion and siltation, stable riverbank, and not prone to direct impact from wind and waves.
Article 2.1.2 The water level station construction plan must be determined after comprehensive technical and economic comparison based on the river topography, riverbed evolution, hydrological characteristics, hydraulic conditions and water level station working conditions provided by the survey.
Article 2.1.3 When a water level station is to be developed into a hydrological station according to the hydrological station network planning, the station site should be selected according to the requirements of the hydrological station. Section 2 Determination of the base surface
Article 2.2.1 The base surface used for water level observation should comply with the following provisions: 1. If a water level station has been established, the original base surface should be frozen and used as the frozen base surface.
, Newly established stations should use the same base surface as the upstream and downstream stations, and use it as the frozen base surface of the station.
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3. Water level stations that have already adopted the station base surface can continue to use it. 4. The frozen base surface used by the water level station should be connected with the current national elevation base surface in my country as soon as possible, and the conversion relationship between the base surface used by the station and the national elevation base surface should be stated in various water level and elevation data.
Section 3 Setting of Level Points
Article 2.3.1 The setting of level points of the station shall comply with the following provisions: 1. The basic level point shall be set above the highest water level in the past years near the station, with stable terrain and convenient for measurement and protection. When there is a national leveling point near the survey station, a basic leveling point can be set. When it is difficult to connect the survey station with the national leveling point, three basic leveling points should be set at different locations, and one of them should be selected as the common leveling point. 2. When the basic leveling point is far away from the water level section, the verification leveling point should be set at a location that is convenient for measurement and stable. When the basic leveling point is close to the water level section, it may not be set.
3. The leveling points of the survey station should be uniformly numbered and remain unchanged. Article 2.3.2 Minimum burial depth of the bottom layer of the basic leveling point; in non-frozen areas, it is recommended to be Xx
Figure 2.3.2 Schematic diagram of leveling point burial
1—marking cover, 2—leveling point mark; 3—iron pipe; 4—concrete base, 5
—iron shaft root network, 6-
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—concrete bottom layer.
W·3·
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is 1.2~1.5m, and the thickness of the frozen soil layer is preferably 2.0m in areas with a thickness of less than 1.5m, and the thickness of the frozen soil layer is preferably 1.0m below the frozen soil layer in areas with a thickness of more than 1.5m. See Figure 2.3.2. The leveling point can be cast directly on the bedrock or a stable permanent building. When casting the leveling point on the bedrock, a solid and stable rock should be selected. When there is a weathered layer on the rock surface, it should be removed first: when the bedrock is exposed to the ground, a hole groove can be drilled on the rock, and the metal or magnetic material mark can be cast in the hole groove. When the bedrock is not too deep from the ground, the iron pipe or steel rail with a concrete base should be fixed to the bedrock first, and then the leveling mark should be cast on the top of the iron pipe filled with cement mortar. When steel rails are used, they should be directly rotated into a semi-spherical shape at the upper end as the leveling mark.
Article 2.3.3 The verification leveling point can be made of long cylindrical stones, concrete piles or reinforced concrete piles, with the upper end chiseled or cast into a semi-spherical mark and the lower end cast into a concrete base. Or chiseled on solid rock or cast on a stable permanent building. The minimum penetration depth of the verification leveling point can be implemented according to the provisions of the basic leveling point.
Article 2.3.4 The elevation measurement of the leveling point shall comply with the following provisions. 1. Except for those included in the national first, second and third class non-standard network, the elevation of the basic leveling point shall be measured from the national second and third class leveling points with a leveling not lower than the third class. Once the national leveling point is selected, it shall not be changed at will unless there are special circumstances. 2. The check leveling point shall be measured from the basic leveling point by third-order leveling. When the conditions are not met, the fourth-order leveling can be used.
3. For stations with poor stability of leveling points or high requirements for water level accuracy, the basic leveling point should be calibrated once every 3 to 5 years, and other stations should be calibrated once every 5 to 10 years. The check leveling point should be calibrated once a year. When there are signs of change, it should be calibrated in time. 4. When there are check leveling points near the upper and lower gradient sections, and the sum of the distances measured from the basic leveling point to the two check leveling points is not much different from the distance between the two check points, one of the basic leveling points should be measured first, and then the other one should be measured. When the basic leveling point is between the check leveling points of the upper and lower gradient sections, they can be measured separately. Engineering Construction Standard Full Text Information System
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Section 4 Layout of Water Scale Section
Article 2.4.1 The layout of basic water scale section shall comply with the following provisions: 1. The basic water scale section of the river water level station shall be located in the middle of the straight river section and perpendicular to the flow direction.
2. The upstream basic water scale section of the weir gate water level station shall be located at the place where the water flow is stable upstream of the weir gate, and the distance from the weir gate should not be less than 3 to 5 times the maximum head: The downstream basic water scale section shall be located at the place where the water flow is stable downstream of the gate, and the distance from the end of the energy dissipation device should not be less than 3 to 5 times the total length of the energy dissipation device.
3. The basic water scale of the reservoir water level station shall be located at the place where the water flow is stable upstream of the dam. When the water level on the dam cannot represent the water level on the gate, a water scale on the gate shall be set separately. When the water level downstream of the dam is required to push the flow, a water gauge section should be set up near the downstream where the water flow is stable. 4. The basic water gauge section of the lake water level station should be set up at a representative place where the water flow is stable. Article 2.4.2 The layout of the gradient water gauge section should comply with the following provisions: 1. For stations that require gradient observation, upper and lower gradient water gauge sections should be set up upstream and downstream of the basic water gauge section. When restricted by the terrain, the basic water gauge section can be used as the upper or lower gradient section.
2. The gradient water gauge section should be set up on a straight river section. There should be no external water inflow or internal water outflow between the upper and lower gradient sections, and there should be no obvious turning point in the gradient between the river bottom and the water surface. The spacing between the upper and lower gradient sections should make the comprehensive uncertainty of the measured gradient not exceed 15% (confidence level is 95%).
3. The measurement of the distance between the gradient sections, the round-trip discrepancy value, should be less than 1/1000 of the measuring section distance.
4. The spacing of the gradient sections can be calculated as follows: 1. When the leveling point is checked on a section: L=ZZx
（S+/+22zxS）
Wherein, L is the spacing of the gradient sections (km);
(2.4.2-1)
Sg is the standard deviation of the water level reading of the water gauge (mm), no waves or still water engineering construction standard full text information system
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equipment is 5mm,
Sm is the standard deviation of leveling on a 1km line (mm), the third-class leveling is 6mm, the fourth-class leveling is 10mm,
Xs is the allowable comprehensive uncertainty of gradient observation (15%); △Z is the drop in the river channel of 1km (mm). When the drop amplitude is large, the appropriate △Z value should be selected according to the main purpose of the gradient observation. Generally, the drop value at the middle water level can be selected for the measuring station.
2. When the upper and lower gradient sections are respectively provided with check leveling points, and one of the check leveling points is measured by the third-class leveling from the basic leveling point through another check leveling point: 2
/s（Lu+Li）+SmL+2Sg
L=NZ·Xs
Wherein, S㎡ is the standard deviation of the third-class leveling measurement on a 1km line; (2.4.2-2)
L.— is the average distance from the upper section leveling point to the upper section water gauge (km); L1 is the average distance from the lower section leveling point to the lower section water gauge (km). Section 5 Topographic Survey and Large Section Survey of Water Level Stations Article 2.5.1 Water level stations may only conduct simple topographic surveys. When there are high requirements for the use of the station topographic map, it should be implemented in accordance with the current relevant standards. Article 2.5.2 Simple topographic survey of water level station shall be carried out in the initial stage of station establishment. When there are significant changes in river course, topography and landform, full or partial re-survey may be carried out according to the changes. When there is a topographic map suitable for the application of the survey station in the area, additional surveying and mapping may be carried out as needed.
Article 2.5.3 The survey scope and surveying content of simple topography of water level station shall be implemented in accordance with the current relevant standards. The plane control of simple topographic survey can be carried out by sight line or compass line. The side length of sight line can be measured by sight method, and the compass line can be measured by steel ruler or tape measure. The angle of sight line can be measured by half-circle survey of theodolite, and the angle of compass line can be measured by compass with scale to half degree. Fourth-class leveling shall be used for elevation control. The elevation of measuring points other than leveling points and elevation control points can be measured by sight height difference.
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W.bzsoso.coI4. The elevation measurement of leveling points shall comply with the following provisions. 1. Except for those included in the national first, second and third class inaccurate network, the elevation of basic leveling points shall be measured from the national second and third class leveling points using a leveling not lower than the third class. Once the national leveling points used for reference are selected, they shall not be replaced at will unless there are special circumstances. 2. The verification leveling points shall be measured from the basic leveling points using the third class leveling. When conditions are not met, the fourth class leveling may be used.
3. For stations with poor stability of leveling points or high requirements for water level accuracy, the basic leveling points should be calibrated once every 3 to 5 years, and other stations should be calibrated once every 5 to 10 years. The verification leveling points should be calibrated once a year. When there are signs of change, they should be calibrated in time. 4. When there are check leveling points near the upper and lower gradient sections, and the sum of the distances measured from the basic leveling point to the two check leveling points is not much different from the distance between the two check points, one of the basic leveling points should be measured first, and then the other one should be measured. When the basic leveling point is between the check leveling points of the upper and lower gradient sections, they can be measured separately. Engineering Construction Standard Full Text Information System
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Section 4 Layout of Water Scale Sections
Article 2.4.1 The layout of basic water scale sections shall comply with the following provisions: 1. The basic water scale section of the river water level station shall be located in the middle of the straight river section and perpendicular to the flow direction.
2. The upstream basic water level section of the weir gate water level station should be set at the place where the water flow is stable upstream of the weir gate, and the distance from the weir gate should not be less than 3 to 5 times the maximum water head: the downstream basic water level section should be set at the place where the water flow is stable downstream of the gate, and the distance from the end of the energy dissipation device should not be less than 3 to 5 times the total length of the energy dissipation device.
3. The basic water level of the reservoir water level station should be set at the place where the water flow is stable upstream of the dam. When the water level on the dam cannot represent the water level on the gate, a water level on the gate should be set separately. When the water level downstream of the dam is required to push the flow, a water level section should be set near the place where the downstream water flow is stable. 4. The basic water level section of the lake water level station should be set at a representative place where the water flow is stable. Article 2.4.2 The layout of the gradient water level section shall comply with the following provisions: 1. For stations that require gradient observation, upper and lower gradient water level sections should be set up upstream and downstream of the basic water level section. When restricted by terrain, the basic water level section can be used as the upper or lower gradient section.
2. The gradient water level section should be set on the straight river section. There should be no external water inflow or internal water outflow between the upper and lower gradient sections, and there should be no obvious turning point in the gradient between the river bottom and the water surface. The spacing between the upper and lower gradient sections should make the comprehensive uncertainty of the measured gradient not exceed 15% (confidence level is 95%).
3. When measuring the spacing between gradient sections, the round-trip discrepancy value should be less than 1/1000 of the measuring section distance.
4. The spacing of the gradient sections can be calculated as follows: 1. When the leveling point is checked on a section: L=ZZx
（S+/+22zxS）
Wherein, L is the spacing of the gradient sections (km);
(2.4.2-1)
Sg is the standard deviation of the water level reading of the water gauge (mm), no waves or still water engineering construction standard full text information system
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equipment is 5mm,
Sm is the standard deviation of leveling on a 1km line (mm), the third-class leveling is 6mm, the fourth-class leveling is 10mm,
Xs is the allowable comprehensive uncertainty of gradient observation (15%); △Z is the drop in the river channel of 1km (mm). When the drop amplitude is large, the appropriate △Z value should be selected according to the main purpose of the gradient observation. Generally, the drop value at the middle water level can be selected for the measuring station.
2. When the upper and lower gradient sections are respectively provided with check leveling points, and one of the check leveling points is measured by the third-class leveling from the basic leveling point through another check leveling point: 2
/s（Lu+Li）+SmL+2Sg
L=NZ·Xs
Wherein, S㎡ is the standard deviation of the third-class leveling measurement on a 1km line; (2.4.2-2)
L.— is the average distance from the upper section leveling point to the upper section water gauge (km); L1 is the average distance from the lower section leveling point to the lower section water gauge (km). Section 5 Topographic Survey and Large Section Survey of Water Level Stations Article 2.5.1 Water level stations may only conduct simple topographic surveys. When there are high requirements for the use of the station topographic map, it should be implemented in accordance with the current relevant standards. Article 2.5.2 Simple topographic survey of water level station shall be carried out in the initial stage of station establishment. When there are significant changes in river course, topography and landform, full or partial re-survey may be carried out according to the changes. When there is a topographic map suitable for the application of the survey station in the area, additional surveying and mapping may be carried out as needed.
Article 2.5.3 The survey scope and surveying content of simple topography of water level station shall be implemented in accordance with the current relevant standards. The plane control of simple topographic survey can be carried out by sight line or compass line. The side length of sight line can be measured by sight method, and the compass line can be measured by steel ruler or tape measure. The angle of sight line can be measured by half-circle survey of theodolite, and the angle of compass line can be measured by compass with scale to half degree. Fourth-class leveling shall be used for elevation control. The elevation of measuring points other than leveling points and elevation control points can be measured by sight height difference.
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W.bzsoso.coI4. The elevation measurement of leveling points shall comply with the following provisions. 1. Except for those included in the national first, second and third class inaccurate network, the elevation of basic leveling points shall be measured from the national second and third class leveling points using a leveling not lower than the third class. Once the national leveling points used for reference are selected, they shall not be replaced at will unless there are special circumstances. 2. The verification leveling points shall be measured from the basic leveling points using the third class leveling. When conditions are not met, the fourth class leveling may be used.
3. For stations with poor stability of leveling points or high requirements for water level accuracy, the basic leveling points should be calibrated once every 3 to 5 years, and other stations should be calibrated once every 5 to 10 years. The verification leveling points should be calibrated once a year. When there are signs of change, they should be calibrated in time. 4. When there are check leveling points near the upper and lower gradient sections, and the sum of the distances measured from the basic leveling point to the two check leveling points is not much different from the distance between the two check points, one of the basic leveling points should be measured first, and then the other one should be measured. When the basic leveling point is between the check leveling points of the upper and lower gradient sections, they can be measured separately. Engineering Construction Standard Full Text Information System
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Section 4 Layout of Water Scale Sections
Article 2.4.1 The layout of basic water scale sections shall comply with the following provisions: 1. The basic water scale section of the river water level station shall be located in the middle of the straight river section and perpendicular to the flow direction.
2. The upstream basic water level section of the weir gate water level station should be set at the place where the water flow is stable upstream of the weir gate, and the distance from the weir gate should not be less than 3 to 5 times the maximum water head: the downstream basic water level section should be set at the place where the water flow is stable downstream of the gate, and the distance from the end of the energy dissipation device should not be less than 3 to 5 times the total length of the energy dissipation device.
3. The basic water level of the reservoir water level station should be set at the place where the water flow is stable upstream of the dam. When the water level on the dam cannot represent the water level on the gate, a water level on the gate should be set separately. When the water level downstream of the dam is required to push the flow, a water level section should be set near the place where the downstream water flow is stable. 4. The basic water level section of the lake water level station should be set at a representative place where the water flow is stable. Article 2.4.2 The layout of the gradient water level section shall comply with the following provisions: 1. For stations that require gradient observation, upper and lower gradient water level sections should be set up upstream and downstream of the basic water level section. When restricted by terrain, the basic water level section can be used as the upper or lower gradient section.
2. The gradient water level section should be set on the straight river section. There should be no external water inflow or internal water outflow between the upper and lower gradient sections, and there should be no obvious turning point in the gradient between the river bottom and the water surface. The spacing between the upper and lower gradient sections should make the comprehensive uncertainty of the measured gradient not exceed 15% (confidence level is 95%).
3. When measuring the spacing between gradient sections, the round-trip discrepancy value should be less than 1/1000 of the measuring section distance.
4. The spacing of the gradient sections can be calculated as follows: 1. When the leveling point is checked on a section: L=ZZx
（S+/+22zxS）
Wherein, L is the spacing of the gradient sections (km);
(2.4.2-1)
Sg is the standard deviation of the water level reading of the water gauge (mm), no waves or still water engineering construction standard full text information system
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equipment is 5mm,
Sm is the standard deviation of leveling on a 1km line (mm), the third-class leveling is 6mm, the fourth-class leveling is 10mm,
Xs is the allowable comprehensive uncertainty of gradient observation (15%); △Z is the drop in the river channel of 1km (mm). When the drop amplitude is large, the appropriate △Z value should be selected according to the main purpose of the gradient observation. Generally, the drop value at the middle water level can be selected for the measuring station.
2. When the upper and lower gradient sections are respectively provided with check leveling points, and one of the check leveling points is measured by the third-class leveling from the basic leveling point through another check leveling point: 2
/s（Lu+Li）+SmL+2Sg
L=NZ·Xs
Wherein, S㎡ is the standard deviation of the third-class leveling measurement on a 1km line; (2.4.2-2)
L.— is the average distance from the upper section leveling point to the upper section water gauge (km); L1 is the average distance from the lower section leveling point to the lower section water gauge (km). Section 5 Topographic Survey and Large Section Survey of Water Level Stations Article 2.5.1 Water level stations may only conduct simple topographic surveys. When there are high requirements for the use of the station topographic map, it should be implemented in accordance with the current relevant standards. Article 2.5.2 Simple topographic survey of water level station shall be carried out in the initial stage of station establishment. When there are significant changes in river course, topography and landform, full or partial re-survey may be carried out according to the changes. When there is a topographic map suitable for the application of the survey station in the area, additional surveying and mapping may be carried out as needed.
Article 2.5.3 The survey scope and surveying content of simple topography of water level station shall be implemented in accordance with the current relevant standards. The plane control of simple topographic survey can be carried out by sight line or compass line. The side length of sight line can be measured by sight method, and the compass line can be measured by steel ruler or tape measure. The angle of sight line can be measured by half-circle survey of theodolite, and the angle of compass line can be measured by compass with scale to half degree. Fourth-class leveling shall be used for elevation control. The elevation of measuring points other than leveling points and elevation control points can be measured by sight height difference.
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W.bzsoso.coIArticle 1 Water level stations may only conduct simple topographic surveys. When there are high requirements for the use of station topographic maps, they should be implemented in accordance with the current relevant standards. Article 2.5.2 Simple topographic surveys of water level stations should be conducted in the early stage of station establishment. When there are significant changes in the river channel, topography, and landforms, they can be fully or partially re-surveyed according to the changes. When a topographic map suitable for station application is measured in the area, additional surveying and mapping can be carried out as needed.
Article 2.5.3 The measurement scope and surveying content of simple topography at water level stations should be implemented in accordance with the current relevant standards. The plane control of simple topographic surveys can be carried out by sight traverses or compass traverses. The side length of the sight traverse can be measured by the sight method, and the compass traverse can be measured by a steel ruler or a tape measure. The angle of the sight traverse can be measured by a half-turn of theodolite, and the angle of the compass traverse can be measured by a compass with a scale of half a degree. Fourth-class leveling should be used for elevation control. The elevation of measuring points other than leveling points and elevation control points can be measured by sight height difference.
Engineering Construction Standard Full Text Information System
W.bzsoso.coIArticle 1 Water level stations may only conduct simple topographic surveys. When there are high requirements for the use of station topographic maps, they should be implemented in accordance with the current relevant standards. Article 2.5.2 Simple topographic surveys of water level stations should be conducted in the early stage of station establishment. When there are significant changes in the river channel, topography, and landforms, they can be fully or partially re-surveyed according to the changes. When a topographic map suitable for station application is measured in the area, additional surveying and mapping can be carried out as needed.
Article 2.5.3 The measurement scope and surveying content of simple topography at water level stations should be implemented in accordance with the current relevant standards. The plane control of simple topographic surveys can be carried out by sight traverses or compass traverses. The side length of the sight traverse can be measured by the sight method, and the compass traverse can be measured by a steel ruler or a tape measure. The angle of the sight traverse can be measured by a half-turn of theodolite, and the angle of the compass traverse can be measured by a compass with a scale of half a degree. Fourth-class leveling should be used for elevation control. The elevation of measuring points other than leveling points and elevation control points can be measured by sight height difference.
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