JP3546349B2 - Water surface gradient observation system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus used for river planning and river management (mainly flood control activities), and for continuously and automatically observing the water surface gradient of a river.
[0002]
[Prior art]
Conventionally, as a method of continuously and automatically measuring river flow, in addition to the HQ curve method and water measuring facility method using only the water level as a measurement amount, the Doppler method using water velocity as a target variable, water surface gradient method, image analysis There is a method.
At present, the HQ curve method, which is mechanically simple and does not require special structures, is mainly used, but this method is only applicable when there is uniqueness between water level and discharge. Because it is possible and cannot be applied at locations affected by backwater, there is a problem that effective observation values cannot be collected in rivers that have problems such as flooding and pollution.
Among the above three methods of measuring the flow velocity, the water surface gradient method has been found to be effective in principle, and some methods have been patented and have been used in actual rivers (Japanese Patent No. 1448747).
[0003]
[Problems to be solved by the invention]
However, since the measurement method was a “water level difference reproduction type” in which water pipes were laid at two points in the longitudinal direction of the river and water was collected at one point, it was physically difficult to maintain watertightness and airtightness at the joints of the pipes. There is a drawback that it requires complicated maintenance work.
[0004]
In the process of installing and operating the above-mentioned "water level difference reproduction type" measuring device on an actual river, it is possible to obtain regular maintenance at least for one month and 1-2 weeks after stabilization until the observation data becomes stable. The normal operation holding period was an average of 2 to 3 months, which was difficult to employ in practice.
In addition, the drainage operation of the drainage pump / Oke-mon / Oke-pipe is operated based on the water level difference between the Honkawa and tributaries (especially the direction of flow), so as not to cause backflow from the Honkawa to the tributaries. Although it is necessary, the current situation is generally based on the visual judgment of the operator, and especially at night, the visibility range is limited, and flooding accidents due to human error are reported every year.
[0005]
Conventional flow meters are roughly classified into a sensor system that directly detects the direction of flowing water and a ball system that determines the direction based on the movement of the ball. Mold "and has similar difficulties in maintaining water permeability. Further, there is a problem that even if the detected flow direction is edited and displayed as numerical data, it is difficult to determine it as information on the gate operation.
The present invention has been made in view of the above-described problems of the prior art, and does not change the state of the water surface, has a simple structure, can maintain stable operation for a long period of time, and allows an operator to easily determine a water level difference and a flow direction. It is an object of the present invention to provide a water surface gradient observing system capable of performing the above.
[0006]
[Means for Solving the Problems]
For this reason, the water surface gradient observation system of the present invention uses the water depth signal (water level) detected by the water pressure type water level meter arranged at two points in the longitudinal direction of the river to determine the water level difference with continuity required for river management. A potential difference conversion unit for converting into a potential difference for detection, a data processing device for automatically calculating a water surface gradient, a flow direction, and a flow rate from the potential difference (water level difference); and a circuit branching of the obtained potential difference signal. required over the gate opening and closing of the gutter pipe, Ri Do and a display device for visual representation of small changes in the flow direction-level difference, the data processing device detects the potential difference signal input from the potential conversion section gate A detection input unit to which the open / close detector is connected, a data conversion unit that calculates water surface gradient, flow direction, and flow rate from the potential difference signal and converts the data into hydrological information, and a data control unit that converts each data into numerical information and performs time control. Composed of Is the water level difference is characterized in that it has to be observed as a continuous analog value.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described based on examples shown in the drawings.
The present invention has developed a "potential difference conversion type" observation method using a water level difference as a potential difference by utilizing the fact that the water level of the water pressure type water level meter has a high linearity with respect to the signal voltage. The detection target in this method is the water pressure corresponding to the water depth in the natural state of the river.Since the water pressure gauge, which is widely used in rivers and wells, is adopted as a sensor, the river flow is artificially detected. There is no need to control, and the complexity of maintenance work required by the conventional water surface gradiometer is relieved.
[0009]
【Example】
FIG. 1 is an explanatory view showing the principle of the water surface gradient measurement according to the present invention, and FIG. 2 is a block diagram showing the outline of the system of the present invention. 1A and 1B are two points in the longitudinal direction of the river, that is, upstream and downstream. The hydraulic water level gauges 2 installed on each side are a potential difference conversion unit that converts a signal of the water depth (a voltage signal of the water level difference) detected by the water pressure type water gauge into a potential difference matched with the water level elevation difference.
[0010]
The data processing device 3 automatically detects and calculates a water surface gradient, a flow direction, and a flow rate from the obtained potential difference signal and converts the data into hydrological information. The detection input unit 4 detects the potential difference signal input from the potential difference conversion unit 2. And a data control unit 6 for converting each data into numerical information, storing the converted data, and performing communication line control, voice conversion control, date and time control, and the like. The received hydrological information can be communicated to the personal computer 9 of the receiving place 8 through the telephone line 7. Reference numeral 10 denotes a data output printer.
[0011]
A rain gauge 12 and a gate opening / closing detector 13 are connected to the detection input unit 4 of the data processing device 3. Here, the flow direction is obtained by detecting the water level difference at the two points of the confluence of the Honkawa and the tributaries, but since the water level difference is observed as a continuous analog value, the change of the merging relation can be grasped over time, and the gate operation is performed. Timing is easy to achieve. However, even if the detected flow direction is edited and displayed as numerical data, it is difficult to determine it as information on the gate operation. Therefore, as a display method for an outdoor worker who visually notifies the water level difference and the flow direction, a light bar type electronic display panel 11 branched from the potential difference conversion unit 2 is provided.
[0012]
The water surface gradient I is obtained by measuring the water level difference ΔH between two cross sections of the section distance L, and as I = ΔH / L. In order to process the water level difference as a potential difference, a conversion means having a function of calibrating the water level elevation difference by surveying as a potential difference conversion result is required, but a voltage signal of two hydraulic pressure gauges is input and a new water level difference is inputted. The problem was solved by developing a potential difference converter that outputs a signal and providing a span adjustment function corresponding to the zero point of the water level difference signal and the maximum detected water level difference.
[0013]
As shown in FIG. 1, E ₁ and E ₂ are signal voltages corresponding to the respective water depths from the water level of the two water level gauges to the machine zero point, and S is for adjusting the error of the mechanical zero point and the height difference of the water level gauge zero point. Is the potential shift value. Here, the following equation (1)
ΔH = E ₁ − (E ₂ −S) (1)
, A water level difference measurement value ΔH is obtained from か ら H, and a water surface gradient / flow direction (positive or negative of the water surface gradient) is calculated from △ H. The discharge is a calculation result from a hydraulic equation that uses the water level and water surface gradient as independent variables.The above conversion and calculation are processed, edited and stored as observation data, and data is transmitted through communication with external receiving equipment. Is controlled by the data processing device 5 that provides the data (see FIG. 2).
[0014]
The water surface gradient I and downstream water level H ₂ using a cross-sectional characteristics as the reference, the flow rate is determined by such flow calculation using equation (2) and (3).
v = 1 / n * I ^1/2 * R ^2/3 (2)
Q = A * v (3)
In order to verify the validity of the water surface gradient method, two water level gauges were laid on a three-sided glass-clad experimental waterway with the same cross section, and the flow rate was compared with the flow rate calculated by the water surface gradient. As shown in FIG. 3, a good correspondence was required. The flow rate was generated by overflow from a water tank provided with a triangular weir, and a random time change was given while grasping the flow rate by a hydraulic equation.
[0015]
In order to verify the application of the water surface gradient method to actual rivers, a straight line and straightening river channel of the Kumano River in the Kiyotake River system were selected, a rainfall, water level, water surface gradient observation station was newly established, and the water surface gradient was continuously and automatically measured. On both October 12 and October 17, 1998, normal flood flow observations were carried out by measuring the overdraft flow velocity, and the results were compared with the calculated flow values from the measured water level and water surface gradient. Two types of floats were used, with draft lengths of 30 cm and 50 cm, depending on the fluctuation of the water level. The number of observation points was 1 (river width was about 5 m), and the calibration coefficient was a standard value of 0.88.
The roughness coefficient n in the above equation (2) is unknown, and if n is determined, the flow velocity is calculated as a function value of the water level / water surface gradient. By transforming equation (2),
n = I ^1/2 * R ^2/3 / v (4)
And given the diameter depths R and v determined from the measurement records I and H, the roughness coefficient n is calculated. Here, n is obtained by applying the velocity at the time of flood flow observation to v. FIG. 4 shows the relationship between the measured flow rate Q and the roughness coefficient n from the measurement record. The result was sufficient to confirm the validity of the water gradient method in the Kumano River. with a mean value of n calculated results and coefficient of roughness Kumanogawa it has been created to the graph shown in FIG. 5 compares the flow rate Q and flood flow observations Q ₀ which is again calculated from equation (2), the graph of FIG. 4 As can be seen from the above, the coincidence is high, reflecting that the distribution of the roughness coefficient was uniform in the above equation (4).
[0016]
The flow rate observation using the water surface gradient formula is a method that focuses on the fact that the flow rate has a functional relationship with the water level (and the cross-sectional characteristics derived from the water level) and the water surface gradient as independent variables. Fig. 6 is a scatter plot of the relationship between water surface gradient and flow rate, which was rarely reported as a result of conventional observation. The effect of the water surface gradient on the flowing water has appeared, confirming the effectiveness of this method.
[0017]
The construction of the new observatory in Kumano River was completed in one day, except for the power supply and telephone plug-in work to go online, and stable equipment status was maintained immediately after installation. The regular maintenance work is only weeding on the river channel for flood flow observation, and the observation device body has been operating without maintenance until now.
At this stage, the water surface gradient method can be a method for solving the problems of installability and maintainability to some extent as compared with the water surface gradiometer that has been reported conventionally.
[0018]
【The invention's effect】
As described above, the water surface gradient observation system of the present invention has the following excellent effects.
(1) Observation and survey costs are difficult to secure, so there is absolutely a shortage of observation flow data required for river planning. On the other hand, the proportion of flood damage amount is increasing every year. Observation means that can be introduced to rivers can be provided.
(2) As a result of the above (1), it is possible to formulate an appropriate plan that does not cause excessive construction or lack of flow capacity due to the river plan being formulated based only on theoretical values.
(3) As the river information in the current flood control activities, the water level is the only criterion such as the "warning water level". However, a sudden increase in the inflow from the upstream and a sudden rise in the water level due to flooding on the downstream side Appearing on the water surface gradient, it serves as a predictor of short-term river inundation risk, and also provides basic information for understanding long-term changes in the basin.
(4) In this method, since there is no laying of water pipes, the installation relationship between the two measurement points is free, and the Honkawa / Shikawa in the form of straddling the embankment such as drainage pump, tub gate, tub pipe, etc. Can be measured. In particular, it is possible to detect a flow direction necessary for a gate operation that does not cause a backflow to the tributary side, thereby reducing a burden on an operator and preventing an erroneous operation.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the principle of water surface gradient measurement according to the present invention.
FIG. 2 is a block diagram showing the outline of the system of the present invention.
FIG. 3 is a graph showing a comparison between a measured flow rate in an experimental channel and a calculated flow rate by a water surface gradient method.
FIG. 4 is a graph showing a relationship between an actually measured flow rate and a roughness coefficient in an actual river (Kumano River).
FIG. 5 is a graph showing a comparison between a flood observation flow rate in a real river (Kumano River) and a flow rate calculated by a water surface gradient method.
FIG. 6 is a graph showing a relationship between a water surface gradient and a flow rate in an actual river (Kumano River).
FIG. 7 is an explanatory view showing one embodiment of a light bar type electric light display panel.
[Explanation of symbols]
Reference Signs List 1A Water pressure gauge 1B Water pressure gauge 2 Potential difference conversion unit 3 Data processing unit 4 Detection input unit 5 Data conversion unit 6 Data control unit 7 Telephone line 8 Receiving station 9 PC 10 Printer 11 Light bar type electronic display 12 Rain gauge 13 Gate open / close detector

Claims (1)

A potential difference conversion unit that converts a water depth signal (water level) detected by a water pressure type water level meter placed at two points in the longitudinal direction of the river into a potential difference for detecting a water level difference that maintains continuity required for river management. And a data processing device for automatically calculating a water surface gradient, a flow direction, and a flow rate from the potential difference (water level difference), and a circuit branching of the obtained potential difference signal, which is required for gate opening / closing operation of a drainage station / gutter pipe. Ri Do and a display device for visual representation of small changes in the flow direction-level difference, the data processing apparatus includes a detection input unit detects a potential difference signal input from the potential conversion unit gated detector is connected , A data conversion unit that calculates the water surface gradient, flow direction, and flow rate from the potential difference signal and converts it to hydrological information, and a data control unit that converts each data to numerical information and performs time control.The water level difference is a continuous analog value. Observed Water gradient observation system being characterized in that the so that.

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