Method for measuring winter runoff of small watershed in cold region

Abstract

The present application belongs to the technical field of basin hydrology monitoring, and particularly relates to a method for measuring winter runoff of a small basin in a cold region. A flow measuring weir is arranged at a water outlet of a catchment area of a small basin in a cold region, a flow guide pipe is arranged at the bottom of the flow measuring weir, and a low-temperature radar flowmeter is arranged at the top center position inside the flow guide pipe to measure the runoff. The present application provides a method for measuring winter runoff of a small basin in a cold region. The method constructs a flow measuring weir, sets a flow guide pipe to guide the flow, introduces the runoff of the small basin from the ground surface to the underground, ensures the normal flow of the runoff water during the ice formation period in winter, thereby avoiding the adverse effects of water freezing on the measurement of the runoff, and accurately measures the flow rate and flow of the winter runoff by using the low-temperature flowmeter.

Description

Technical Field

[0001] This invention belongs to the field of watershed hydrological monitoring technology, specifically relating to a method for measuring winter runoff in small watersheds in cold regions. Background Technology

[0002] Accurate measurement of winter runoff in small watersheds in cold regions has long been a significant challenge. Under low winter temperatures, stable ice sheets form on river surfaces, while subglacial runoff continues. The presence of ice sheets makes it difficult to effectively obtain subglacial flow using traditional runoff measurement methods, leading to a significant increase in the uncertainty and error of the observed data.

[0003] Winter runoff measurement in cold regions is one of the core challenges in hydrological observation in these areas. The freezing of water bodies caused by low temperatures restricts the applicability and accuracy of traditional measurement methods (such as the velocity-area method, buoy method, and fixed-point monitoring at hydrological stations). Due to river ice formation, conventional current meters and buoy methods often fail because of equipment clogging and limited observation windows. Even with improved methods such as ice hole measurement, ice layers hinder direct contact measurements by current meters and ADCP (Acoustic Doppler Current Profiler), or factors such as differences in current meter suspension methods, turbulent flow under ice, ice-water interface shear flow, and transient changes during the melting period lead to systematic errors of 10%–30%. Related research indicates that the coexistence of multiphase water in cold regions makes traditional hydrological observation equipment difficult to adapt, and data acquisition interruptions or distortions are common phenomena.

[0004] The lack and distortion of winter runoff data pose multiple constraints to comprehensive watershed hydrological management. In the field of water conservancy engineering planning, inaccurate winter baseflow data can lead to deviations in reservoir storage capacity calculations, affecting the optimal allocation of downstream flood control and irrigation water supply capacity, and consequently reducing the safety and economy of engineering designs. In terms of water resource utilization, winter runoff in cold regions accounts for 15%–30% of annual water resources; data gaps can cause inaccurate water supply and demand balance analyses, interfering with the formulation of scheduling plans for agricultural irrigation and urban water supply. Regarding ecological environment assessment, winter runoff is a key element in maintaining river ecosystems in cold regions; data gaps can lead to deviations in ecological flow threshold calculations, making it difficult to accurately assess the migration patterns of pollutants during freeze-thaw periods and the quality of aquatic habitats, thus hindering the scientific rigor of dynamic river health diagnosis. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for measuring winter runoff in small watersheds in cold regions. This method overcomes the limitations of traditional monitoring and can be widely applied to winter runoff monitoring in small watersheds in cold regions, significantly improving monitoring capabilities and accuracy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for measuring winter runoff in a small watershed in a cold region involves setting up a flow-measuring weir at the outlet of the catchment area of ​​the small watershed in the cold region, setting up a guide pipe at the bottom of the flow-measuring weir, and setting up a low-temperature radar flow meter on the top side inside the guide pipe for measuring runoff.

[0007] Specifically: a flow-measuring weir is installed at the outlet of the catchment area in a small watershed in a cold region; a guide pipe is installed at the horizontal center of the bottom of the flow-measuring weir to ensure that the runoff from the catchment area flows out through the guide pipe; a heating device is installed on the outside of the outlet end of the guide pipe to prevent the pipe opening from freezing; a settling tank is installed below the outlet end of the guide pipe to form a stable water level difference; a flow regulation control valve is installed at the inlet end of the guide pipe to regulate the inlet flow rate; and a low-temperature radar flow meter is installed at the center of the top side inside the guide pipe to measure the runoff.

[0008] The cold regions are those where ice covers the river surface in winter, but subglacial runoff still exists.

[0009] The small watershed is a closed catchment unit bounded by the watershed and the downstream channel outlet, with a catchment area of ​​5-30 km². 2 It is a watershed with an independent rainfall-runoff-confluence process and runoff generation in winter.

[0010] Furthermore, the cross-section of the flow measurement weir is trapezoidal, with a top width of 2-3m, a bottom width of 6-9m, a length determined by the width of the river channel, and a height of 4-6m. The effective water storage depth in the catchment area is stably maintained at 3m±0.5m, ensuring that the bottom of the flow measurement weir does not freeze during winter water storage in the catchment area.

[0011] Furthermore, a horizontal guide pipe is installed at the center of the bottom of the flow measurement weir to facilitate the smooth flow of water from the catchment area to the flow measurement area. The guide pipe is a circular reinforced concrete pipe with a length equal to that of the bottom of the flow measurement weir and a diameter of 0.6-1.0m, depending on the area of ​​the small watershed and the size of the winter runoff. The vertical distance between the upper end of the guide pipe inlet and the weir body is 1.5-2.0m, and the vertical distance between the lower end of the inlet and the bottom of the catchment area is at least 0.5m to ensure that there is always runoff in the guide pipe.

[0012] Furthermore, a low-temperature radar flow meter is installed at the top center position 30cm from the outlet of the guide pipe. The operating temperature range of the low-temperature radar flow meter is -40℃ to 50℃, which is suitable for stable operation in low temperatures during winter.

[0013] Furthermore, the heating device is a 5KW warm air blower with a temperature control system, installed on the outside of the water outlet of the guide pipe. The air outlet of the warm air blower faces the guide pipe, and the temperature control probe is placed in the water body of the monitoring section of the low-temperature radar flow meter (the probe must not touch the bottom of the section), with the temperature set at 5℃. At the same time, snow and moisture prevention measures should be taken for the warm air blower to prevent water ingress, short circuits, etc.

[0014] Furthermore, a sedimentation tank is installed outside the outlet of the diversion pipe, with a vertical drop of ≥1.0m between the inlet of the sedimentation tank and the outlet of the diversion pipe to prevent the water flow at the outlet from freezing, blocking the outlet, and affecting normal drainage.

[0015] Furthermore, the flow regulation control valve is a ductile iron valve with a diameter of 0.65-1.05m to ensure complete coverage of the inlet. The operating end of the control valve is connected to a 2m long control rod, which can be used to vertically raise and lower the control valve to meet the flow measurement requirements.

[0016] A device for measuring the winter runoff of a small watershed in a cold region includes a flow measuring weir, a guide pipe, a low-temperature radar flow meter, a heating device, and a flow regulating control valve. The guide pipe is located at the bottom horizontal center of the flow measuring weir. The low-temperature radar flow meter is located at the top of the guide pipe, 30 cm away from the outlet. A heating device is installed on the outside of the outlet end of the guide pipe, and a flow regulating control valve is installed at the inlet end of the guide pipe. The radar flow meter is installed inside the guide pipe, and real-time measurement of the runoff in the small watershed during winter is achieved through the low-temperature radar flow meter.

[0017] The beneficial effects of this invention are as follows: 1. This invention provides a method for measuring the winter runoff of a small watershed in a cold region. By constructing a flow measurement weir and setting up a diversion pipe to guide the runoff from the surface to the ground, the runoff water is ensured to maintain normal flow during the winter freezing period, thereby avoiding the adverse effects of water freezing on runoff measurement. The method also utilizes a low-temperature flow meter to accurately measure the flow velocity and flow rate of the winter runoff.

[0018] 2. This invention provides a method for measuring the winter runoff of small watersheds in cold regions. Through the rational arrangement of a flow-measuring weir, a guide pipe, a settling tank, and a flow control valve, the method ensures the stable flow of water in the small watershed during winter. The flow-measuring weir intercepts the water flow and guides it smoothly into the guide pipe; the settling tank prevents the water from freezing and blocking the outlet; and the flow control valve can flexibly adjust the inlet flow rate. This ensures that the entire measurement system operates stably in the complex winter environment, unaffected by changes in water flow or freezing. Furthermore, this method is convenient and easy to operate, with relatively simple installation and maintenance, reducing measurement costs and improving work efficiency. Attached Figure Description

[0019] Figure 1This is a three-dimensional structural cross-sectional diagram of a method for measuring winter runoff in a small watershed in a cold region, provided by an embodiment of the present invention. Figure 2 This is a three-dimensional planar schematic diagram of a method for measuring winter runoff in a small watershed in a cold region, provided by an embodiment of the present invention. Figure 3 A schematic diagram of a flow guide pipe for a method of measuring winter runoff in a small watershed in a cold region, provided by an embodiment of the present invention; Among them, A-flow measuring weir, B-flow guide pipe, C-low temperature radar flow meter, D-warm air blower, E-flow regulation and control valve, F-water collection area, and G-sinking tank. Detailed Implementation

[0020] This invention provides a method for measuring the winter runoff of small watersheds in cold regions. It is mainly applied to cold regions and solves the technical problem that the runoff of small watersheds cannot be accurately measured due to river freezing in winter.

[0021] The method for measuring winter runoff in a small watershed in a cold region provided by this invention involves setting up a flow-measuring weir at the outlet of the catchment area of ​​the small watershed in the cold region; horizontally setting a guide pipe at the center of the bottom of the flow-measuring weir to ensure that the runoff from the catchment area flows out through the guide pipe; setting up a heating device outside the outlet end of the guide pipe to prevent the pipe opening from freezing; setting up a settling pool below the outlet end of the guide pipe to form a stable water level difference; setting up a flow regulation control valve at the inlet end of the guide pipe to regulate the inlet flow rate; and setting up a low-temperature radar flow meter at the center of the top side inside the guide pipe to measure the runoff.

[0022] The cross-section of the flow measurement weir is trapezoidal, with a top width of 2-3m, a bottom width of 6-9m, a length determined by the width of the river channel, and a height of 4-6m. The effective water storage depth in the catchment area is stably maintained at 3m±0.5m to ensure that the bottom of the flow measurement weir does not freeze during winter.

[0023] A horizontal guide pipe is installed at the center of the bottom of the flow measurement weir to guide the water flow from the catchment area to the flow measurement area smoothly. The guide pipe is circular with a diameter of 0.6-1.0m, depending on the area of ​​the small watershed and the amount of runoff in winter. The length of the guide pipe is the same as the bottom of the flow measurement weir. The vertical distance between the upper end of the guide pipe inlet and the weir body is 1.5-2.0m, and the vertical distance between the lower end of the guide pipe inlet and the bottom of the catchment area is at least 0.5m to ensure that there is always runoff in the guide pipe.

[0024] A low-temperature radar flow meter is installed at the top center position 30cm from the outlet of the guide pipe. The operating temperature range of the low-temperature radar flow meter is -40℃ to 50℃, which is suitable for stable operation in low temperatures during winter.

[0025] The heating device is a 5KW warm air blower with a temperature control system, installed on the outside of the water outlet of the guide pipe. The air outlet of the warm air blower faces the guide pipe. The temperature control probe is placed in the water body of the monitoring section of the low-temperature radar flow meter (the probe must not touch the bottom of the section), and the temperature is set at 5℃. At the same time, snow and moisture protection measures should be taken for the warm air blower to prevent water ingress, short circuits, etc.

[0026] A settling tank is installed outside the outlet of the diversion pipe. The vertical drop between the inlet of the settling tank and the outlet of the diversion pipe is ≥1.0m to prevent the water flow at the outlet from freezing, blocking the outlet, and affecting normal drainage.

[0027] The flow regulating control valve is a ductile iron valve with a diameter of 0.65-1.05m, ensuring complete coverage of the inlet. The operating end of the control valve is connected to a 2m long control rod, which can be used to vertically raise and lower the control valve to meet flow measurement requirements.

[0028] A device for measuring the winter runoff of a small watershed in a cold region includes a flow-measuring weir A, a guide pipe B, a radar flow meter C, a heater D with a temperature control system, and a flow regulating control valve E. The flow-measuring weir A forms a catchment area F at the outlet of the small watershed. The guide pipe B is horizontally installed at the center of the bottom of the weir A. The flow regulating control valve E is installed on the outside of the inlet end of the guide pipe B. The heater D with a temperature control system is installed on the outside of the outlet end of the guide pipe B. Simultaneously, the radar flow meter C is installed inside the guide pipe B. Real-time measurement of the runoff in the small watershed during winter is achieved through the low-temperature radar flow meter.

[0029] Example 1 The experiment was conducted in the Dahu watershed of Changsha Village, Dasuhe Township, Qingyuan Manchu Autonomous County, Fushun City, Liaoning Province (Liaoning Qingyuan Forest Ecosystem National Field Scientific Observation and Research Station). In winter, the river surface is covered by ice, but subglacial runoff still exists. The catchment area is a closed catchment unit bounded by a watershed and the downstream channel outlet, with an area of ​​5.36 km². 2 The catchment area is a watershed with an independent rainfall-runoff-confluence process and runoff generation in winter.

[0030] according to Figure 1-3 As shown, a flow measurement weir A is constructed at the main outlet of this watershed. The top width of the flow measurement weir is 2m, the bottom width is 6m, the length of the flow measurement weir is 7.8m, and the height of the weir body is 4m, forming a small water catchment area F. The effective water storage depth of the water catchment area F is stably maintained at 3m±0.5m, ensuring that the bottom of the flow measurement weir in the water catchment area F does not freeze during winter.

[0031] A guide pipe B is horizontally installed at the center of the bottom of the flow measuring weir A to guide the water flow from the collection area to the flow measuring area smoothly. The guide pipe B is a circular reinforced concrete pipe with a diameter of 0.6m. The upper end of the inlet of the guide pipe B is 2.0m above the top of the flow measuring weir, and a 0.5m drop is maintained between the lower end of the inlet and the bottom to ensure that there is water accumulation below and in front of the inlet end of the guide pipe B, and that there is always runoff inside the guide pipe B.

[0032] A ductile iron valve, with a diameter of 0.65m, is installed on the outside of the inlet end of the guide pipe B as a flow control valve E to cover the inlet. At the same time, a 2m control rod is provided on the upper end of the flow control valve E, which can be adjusted up and down. Using the flow control valve E, the water in the water collection area F is stored to a height of 0.5m above the top of the flow measuring weir A before the water freezes. By adjusting the flow control valve E, the inflow and outflow in the water collection area F are kept consistent.

[0033] A temperature-controlled heater D (5KW) is installed outside the outlet of the guide pipe B as a heating device. The outlet of the heater D faces the guide pipe B, and its temperature probe is placed in the water body of the monitoring section of the low-temperature radar flow meter C (the probe cannot touch the bottom of the section). The temperature is set at 5℃ to ensure that the water flow will not be affected by freezing in the low-temperature environment.

[0034] A settling tank G is installed outside the outlet end of the diversion pipe B to form a drop of more than 1.0m, which prevents the water from freezing and blocking the outlet, ensures normal drainage, and avoids measurement errors caused by poor water flow.

[0035] Inside the guide pipe B, a low-temperature radar flow meter C is installed at the top center position 30cm away from the outlet. The low-temperature radar flow meter C has an operating temperature range of -40℃ to 50℃ and can work stably in cold environments to accurately measure flow data, as shown in Tables 1 and 2.

[0036] According to observational data from December 25-31, 2025, the average daily runoff in this basin was 372 m³. 3 (Table 1) Hourly runoff is 10-38 m³ 3 (Table 2) and when the river is frozen at a minimum temperature of -28℃ (Table 1), making it impossible to observe surface runoff normally using traditional methods, this embodiment can transform open channel observation into underground channel observation, enabling real-time observation of winter runoff.

[0037] Table 1. Daily runoff and weather conditions in the basin from December 26 to 31, 2025

[0038] Table 2. List of Partial Data Collected from December 26-31, 2025

[0039] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0040] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for measuring winter runoff in a small watershed in a cold region, characterized in that, A flow measurement weir is installed at the outlet of the catchment area of ​​a small watershed in a cold region. A flow guide pipe is installed at the bottom of the flow measurement weir, and a low-temperature radar flow meter is installed on the top side inside the flow guide pipe to measure the runoff.

2. The method for measuring winter runoff in a small watershed in a cold region according to claim 1, characterized in that, A flow-measuring weir is installed at the outlet of the catchment area in a small watershed in a cold region; a guide pipe is installed at the horizontal center of the bottom of the flow-measuring weir to ensure that the runoff from the catchment area flows out through the guide pipe; a heating device is installed on the outside of the outlet end of the guide pipe to prevent the pipe opening from freezing; a settling tank is installed below the outlet end of the guide pipe to form a stable water level difference; a flow regulation control valve is installed at the inlet end of the guide pipe to regulate the inlet flow rate; and a low-temperature radar flow meter is installed at the center of the top side inside the guide pipe to measure the runoff.

3. The method for measuring winter runoff in a small watershed in a cold region according to claim 1 or 2, characterized in that, The cold regions are those where ice covers the river surface in winter, but subglacial runoff still exists.

4. The method for measuring winter runoff in a small watershed in a cold region according to claim 1 or 2, characterized in that, The small watershed is a closed catchment unit bounded by the watershed and the downstream channel outlet, with a catchment area of ​​5-30 km². 2 It is a watershed with an independent rainfall-runoff-confluence process and runoff generation in winter.

5. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, The cross-section of the flow measurement weir is trapezoidal, with a top width of 2-3m, a bottom width of 6-9m, a length determined by the width of the river channel, a height of 4-6m, and an effective water storage depth of 3m ± 0.5m in the catchment area.

6. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, The guide pipe is circular with a diameter of 0.6-1.0m. The length of the guide pipe is the same as the bottom of the flow measuring weir. The guide pipe is placed horizontally at the center of the bottom of the flow measuring weir. The vertical distance between the upper end of the guide pipe inlet and the top of the flow measuring weir is 1.5-2.0m, and the vertical distance between the lower end of the guide pipe inlet and the bottom of the catchment area is at least 0.5m.

7. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, A low-temperature radar flow meter is installed on the top side 30cm from the outlet of the guide pipe. The operating temperature range of the low-temperature radar flow meter is -40℃ to 50℃.

8. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, The heating device is a warm air blower with a temperature control system, which is located on the outside of the water outlet of the guide pipe. The air outlet of the warm air blower faces the guide pipe. The temperature control probe is placed in the water body at the monitoring section of the low-temperature radar flow meter, and the temperature is set to 5℃.

9. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, A sedimentation tank is installed outside the outlet of the diversion pipe, with a vertical drop of ≥1.0m between the inlet of the sedimentation tank and the outlet of the diversion pipe.

10. The method for measuring winter runoff in a small watershed in a cold region according to claim 2, characterized in that, The diameter of the flow regulating control valve is 0.65-1.05m.

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