JP2000230224A - Water surface grade observation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water surface grade observation system having a simple structure, capable of keeping a stable operation for a long period, and allowing an operator to easily judge the water level difference and current direction. SOLUTION: This system is constituted of hydraulic water level gauges 1A, 1B arranged at two positions in the longitudinal direction and measuring the water depths at two positions, a potential difference converting section 2 converting the signals of the water depths detected by the hydraulic water level gauges 1A, 1B into a potential difference matched with the water level elevation difference, a data processing device 3 automatically calculating the water surface grade, current direction and flow rate from the potential difference (water level difference), and a display device 11 visually displaying fine changes of the current direction and water level difference required for the gate opening/closing operations of lifting pipes of a drain machine site.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus used for river planning and river management (mainly for flood control), and for continuously and automatically observing the water surface gradient of a river.

[0002]

2. Description of the Related Art Conventionally, as a method for continuously and automatically measuring a river flow, in addition to an HQ curve method and a water measuring facility method using only a water level as a measurement amount, a Doppler method using a flow velocity as a target variable and a water surface. There are gradient method and image analysis 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. Of 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 (Patent No. 14).
No. 48747).

[0003]

However, since the measuring method was a "water level difference reproduction type" in which a water pipe was laid at two points in the longitudinal direction of the river and water was collected at one point, the watertightness and airtightness of the pipe joints were measured. There is a drawback that holding is physically difficult and complicated maintenance work is required.

When the above-mentioned “water level difference reproduction type” measuring device is installed and operated on an actual river, regular maintenance is continued for at least one month until the observation data becomes stable, and every one to two weeks after the stability. The normal operation retention period obtained is an average of 2 to 3 months,
It was difficult to adopt practically. 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 that there is no backflow from the Honkawa to the tributaries. Although it is necessary, at present the situation is generally determined by the visual judgment of the operator, especially at night, the visibility range is limited, and flooding accidents due to human error are reported every year.

[0005] Conventional "flow direction meters" are roughly classified into a sensor type for directly detecting the direction of flowing water and a ball type for judging the direction from the movement of the ball. It is a "water level difference reproduction type" and has the same difficulty 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 a gate operation. The present invention has been made in view of the above-mentioned problems of the prior art, and does not change the state of the water surface, the structure is simple, stable operation can be maintained for a long time, and the operator can easily determine the water level difference and flow direction. It is an object of the present invention to provide a water surface gradient observing system capable of performing the above.

[0006]

Therefore, the water surface gradient observation system of the present invention is disposed at two points in the longitudinal direction.
A water pressure gauge for measuring the water depth at a point, a potential difference conversion unit for converting a water depth signal detected by the water pressure gauge to a potential difference matched to a water level elevation difference, and a water surface gradient, flow direction, and flow rate from the potential difference (water level difference). And a data processing device for performing automatic calculation of

In addition, the potential difference signal obtained by the water surface gradient observation system according to the first aspect is branched into circuits, and minute changes in flow direction and water level difference required for opening and closing the gate of the drainage station / tub pipe are visually recognized. A second feature is that a display device that expresses the image is provided.

[0008]

Next, an embodiment of the present invention will be described with reference to an embodiment 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 a water pressure type water level meter has a high linearity with the signal voltage relationship. The detection target in this method is the water pressure corresponding to the water depth in the natural state of the river.Since a water pressure gauge that is widely used in rivers and wells is used as a sensor, the river flow is artificially detected. There is no need for control, and the complexity of maintenance work required by conventional water surface gradiometers is relieved.

[0009]

1 is an explanatory view showing the principle of 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 show two points in the longitudinal direction of a river.
That is, a hydraulic pressure gauge installed on each of the upstream and downstream sides and a potential difference conversion unit 2 for converting a signal of the water depth (voltage signal of the water level difference) detected by the hydraulic pressure gauge into a potential difference matched with the water level elevation difference. It is.

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 a detection input unit 4 for detecting the potential difference signal input from the potential difference conversion unit 2. It comprises a data conversion unit 5 for converting information into information, and a data control unit 6 for converting each data into numerical information, storing the data, and performing communication line control, voice conversion control, date and time control, and the like. The obtained hydrological information can be communicated to the personal computer 9 of the receiving station 8 through the telephone line 7. Reference numeral 10 denotes a data output printer.

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 determined by detecting the water level difference at two points of the confluence of the Honkawa and the tributaries. Since the water level difference is observed as a continuous analog value, the change of the merging relation can be grasped over time,
The timing of the gate operation 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.

The water surface gradient I is obtained by measuring a water level difference ΔH between two sections having a section distance L, and assuming 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 difference obtained by surveying as a potential difference conversion result is required, but the voltage signal of the 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.

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 mechanical zero point, and S is the error of the mechanical zero point and the altitude difference of the water level gauge. This is a potential shift value for adjustment. Here, the measured water level difference ΔH is obtained from the following equation (1) ΔH = E ₁ − (E ₂ −S) (1), and the water surface gradient / flow direction (positive or negative of the water surface gradient) is obtained from ΔH. Is calculated. Discharge is the result of calculation from the hydraulic equation using water level and water surface gradient as independent variables,
A series of operations are controlled by the data processing device 5 that processes the above conversion and calculation, edits and stores the data as observation data, and provides the data through communication with an external receiving device (see FIG. 2).

[0014] Using the cross-sectional characteristics as water gradient I and the reference downstream water level H _2, 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) To verify the validity of the water surface gradient method, straight lines and the same Two water level gauges were laid in an experimental waterway with a three-sided glass surface and a movable gradient, and a comparison was made between the flow rate and the calculated flow rate based on the water level gradient, and a good correspondence was obtained as shown in FIG.
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.

In order to verify the application of the water surface gradient method to an actual river, a straight line / rectification river channel of the Kumano River of the Kiyotake River water system was selected, and a rainfall / water level / water surface gradient observation station was newly established.
In addition to automatic measurement, October 12 and 1998
Over the two days of March 17, normal flood flow observations were made by measuring the overdraft flow velocity, and the results were compared with those calculated from water level and water surface gradient measurements. 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 is 1 (river width is about 5m) and the calibration coefficient is the standard value of 0.
88. The roughness coefficient n in the above equation (2) is unknown, and when n is determined, the flow velocity is calculated as a function value of the water level / water surface gradient. When the equation (2) is modified, n = I ^1/2 * R ^2/3 / v (4). Is calculated. Here, n is obtained by applying the flow 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 enough to confirm the validity of the water gradient method in the Kumano River. The average value of the calculation results of n is used as the roughness coefficient of Kumano River, and the flow rate Q newly calculated from equation (2)
And comparing the flood flow observations Q ₀ has been created the graph shown in FIG. 5, as can be seen from the graph of FIG. 4, the distribution of the roughness coefficient in the preceding formula (4) were uniformly Reflecting, high consistency.

The flow rate observation using the water surface gradient formula is a technique 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 the water surface gradient and the flow rate, which was rarely reported as a result of conventional observation. The effect of the water surface gradient on the running water has appeared, confirming the effectiveness of this method.

The construction of the new observatory in Kumanogawa was completed in one day except for the power supply and telephone service for online operation, and the 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 any maintenance until now. At this stage, the water surface gradient method can be a method of solving the problems of installation and maintainability to some extent as compared with the water surface gradiometer that has been conventionally reported.

[0018]

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 make an appropriate plan that does not lead to excessive construction or insufficient 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 Appearing on the water surface gradient, it can be used as a predictor of the risk of river inundation in the short term, and can be used as basic information to understand 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 levee such as drainage pump, tub gate, tub pipe, etc. Water level difference measurement becomes possible. 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 an actually 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 level gauge 1B Water pressure level meter 2 Potential difference converter 3 Data processor 4 Detection input unit 5 Data converter 6 Data controller 7 Telephone line 8 Receiver 9 PC 10 Printer 11 Light bar type electronic display 12 Rain gauge 13 Gate open / close detector

Claims (2)

[Claims] 1. A hydraulic water level gauge which is disposed at two points in a longitudinal direction and measures the water depth at these two points, and a potential difference conversion unit which converts a water depth signal detected by the water pressure type water gauge into a potential difference matched with a water level elevation difference. From the potential difference (water level difference)
A water surface gradient observation system, comprising: a data processor for automatically calculating flow direction and flow rate. 2. The potential difference signal obtained by the water surface gradient observation system according to claim 1 is branched into circuits, and a minute change in flow direction and water level difference required for opening and closing the gate of a drainage station / tub pipe is visually recognized. A display device that expresses itself.