Sand basin sand discharging method and sand basin sand discharging system

Abstract

To provide a sand basin sand discharging method which can efficiently remove accumulated sediment or the like from a sand basin, without requiring a large scale construction, and a sand basin sand discharging system which is used for the same.SOLUTION: An intake dam 2 as a sand basin sand discharging system 1 includes: an intake port 3 provided in a revetment part facing a river; a sand basin 52 provided on the downstream of the intake port 3; a sand basin sand discharging gate 56 provided in the sand basin 52 so as to be connected to the river; a conduit 53 provided so as to be adjacent to a training wall of the sand basin 52; an intake port gate 54 installed in the conduit 53 on the downstream of the sand basin 52; an intake weir 58 provided in the river; water level gauges 59a and 59b installed in each of the intake weir 58 and the conduit 53; and a gate opening / closing mechanism 4 for controlling opening / closing operation of the sand basin sand discharging gate 56 and the intake port gate 54, on the basis of a dam water level and a channel water level detected by the water level gauges 59a and 59b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for flushing sediment from a settling basin that removes sediment and other materials that accumulate in a settling basin located downstream of the intake of a water intake dam for a waterway-type hydroelectric power plant, and in particular to a method and system for flushing sediment from a settling basin that does not require large-scale construction work, can efficiently remove accumulated sediment and other materials from the settling basin, and can also be expected to increase power generation output by extending the time during which water can be taken in. [Background technology]

[0002] Intake dams for waterway-type hydroelectric power plants have a settling basin downstream of the intake to settle sediment contained in the water taken in through the intake. If sediment accumulates in this settling basin, the amount of water taken in per unit time through the intake gate of the water conduit decreases, reducing the efficiency of power generation. For this reason, the sediment in the settling basin must be removed periodically.

[0003] Here, the structure of an intake dam for a conduit type hydroelectric power plant will be explained using Figure 4. Figure 4(a) is a plan view of an intake dam for a conduit type hydroelectric power plant, and Figure 4(b) is a cross-sectional view that schematically shows the structure of the headrace 53 shown in Figure 4(a). Note that in Figure 4(a), the river 50 is hatched. As shown in Figures 4(a) and 4(b), after flowing through river 50 in the direction of the arrow, water is taken in from an intake (not shown) installed in revetment section 50a facing river 50, passes under management office 51, and flows into settling basin 52. This water is mixed with river debris such as driftwood and fallen leaves, and sediment, but the sediment settles in settling basin 52. However, since river debris such as driftwood and fallen leaves flows into headrace channel 53 along with the water that overflows headrace wall 52a, a screen 55 is installed in headrace channel 53 upstream of intake gate 54 to remove this river debris. A settling basin sand flushing gate 56 is installed in settling basin 52 so that it opens toward river 50, allowing the momentum of the flowing water to wash away the accumulated sediment toward river 50. In addition, a water intake weir 58 with a dam sand flushing gate 57 is installed on the river 50, and water level gauges 59a and 59b are installed on the water intake weir 58 and the headrace 53, respectively, to detect the dam water level and the waterway water level. The opening and closing operation of the dam sand flushing gate 57 is controlled by a dam sand flushing gate opening and closing mechanism (not shown).

[0004] The opening and closing operation of the dam sand flushing gate 57 will now be described with reference to Figures 5 and 6. Figures 5 and 6 are flowcharts showing the processing steps of the dam sand flushing gate opening and closing mechanism for the dam sand flushing gate 57. In the following description, the automatic control switch ON level L2 and the automatic control switch OFF level L1 represent the reference water levels at which automatic control by the dam sand flushing gate opening and closing mechanism for the dam sand flushing gate 57 is turned ON and OFF, respectively. The automatic control switch ON upper limit level L3 and the automatic control switch ON lower limit level L4 represent the level obtained by adding the dead band water level to the automatic control switch ON level L2 and the level obtained by subtracting the dead band water level from the automatic control switch ON level L2, respectively. The dam sand flushing gate opening and closing mechanism has the function of selecting either an open operation start mode or a close operation start mode to control the opening and closing operation of the dam sand flushing gate 57 when the automatic control switch is ON. 5, if the dam sand flushing gate opening / closing mechanism determines in step S1 that the dam sand flushing gate 57 is in a fully closed state, it proceeds to processing in step S2, and if it determines in step S2 that the automatic control switch of the dam sand flushing gate 57 is ON, it proceeds to processing in step S3. Furthermore, if the dam sand flushing gate opening / closing mechanism determines in step S3 that the dam water level detected by the water level meter 59a is equal to or lower than the automatic control switch OFF level L1, it turns off the automatic control switch of the dam sand flushing gate 57 in step S4, and then returns to processing in step S1. If the dam sand flushing gate opening / closing mechanism determines in step S1 that the dam sand flushing gate 57 is not fully closed, it proceeds to processing in step S10 (see FIG. 6). If the dam sand flushing gate opening / closing mechanism determines in step S2 that the automatic control switch for the dam sand flushing gate 57 is not turned ON, it proceeds to processing in step S5. If the dam water level detected by the water level gauge 59a is equal to or higher than the automatic control switch ON level L2 in step S5, it turns on the automatic control switch for the dam sand flushing gate 57 in step S6 and then proceeds to processing in step S7. If the dam water level detected by the water level gauge 59a is equal to or higher than the automatic control switch ON upper limit level L3 in step S7, it opens the dam sand flushing gate 57 by 10 cm in step S8, pauses processing for 3 minutes in step S9, and then returns to processing in step S1. In addition, if the dam sand flushing gate opening / closing mechanism determines in step S3 that the dam water level is not below the automatic control switch OFF level L1, it proceeds to processing in step S5, and if it determines in step S5 that the dam water level is not above the automatic control switch ON level L2 or if it determines in step S7 that the dam water level is not above the automatic control switch ON upper limit level L3, it returns to processing in step S1.

[0005] As shown in Figure 6, if the dam sand flushing gate opening / closing mechanism determines in step S10 that the dam sand flushing gate 57 is fully open, it proceeds to processing in step S11.If it determines in step S11 that the water intake gate 54 is fully closed, it keeps the dam sand flushing gate 57 fully open in step S12 to promote sand flushing until water intake resumes, but switches the control of the dam sand flushing gate 57 to manual to prevent malfunction. In addition, if the dam sand flushing gate opening / closing mechanism determines in step S10 that the dam sand flushing gate 57 is not fully open, or if it determines in step S11 that the water intake gate 54 is not fully closed, it proceeds to processing in step S13. If the dam sand flushing gate opening / closing mechanism determines in step S13 that the dam water level detected by the water level gauge 59a is below the automatic control switch ON lower limit level L4, it proceeds to processing in step S14, and if it determines in step S14 that the opening of the dam sand flushing gate 57 is 10 cm, it closes the dam sand flushing gate 57 by 10 cm in step S15, pauses processing for 3 minutes in step S16, and then returns to processing in step S1. If the dam sand flushing gate opening / closing mechanism determines in step S13 that the dam water level is not equal to or lower than the automatic control switch ON lower limit level L4, it proceeds to step S17, and if it determines in step S17 that the dam water level detected by the water level gauge 59a is equal to or higher than the automatic control switch ON upper limit level L3, it opens the dam sand flushing gate 57 by 20 cm in step S18 and then proceeds to the processing of step S16. If the dam sand flushing gate opening / closing mechanism determines in step S14 that the opening degree of the dam sand flushing gate 57 is not 10 cm, it closes the dam sand flushing gate 57 by 20 cm in step S19 and then proceeds to the processing of step S16, and if it determines in step S17 that the dam water level detected by the water level gauge 59a is not equal to or higher than the automatic control switch ON upper limit level L3, it returns to the processing of step S1.

[0006] As described above, the opening and closing operation of the dam sand flushing gate 57 is controlled by a dam sand flushing gate opening / closing mechanism based on the dam water level detected by the water level gauge 59a. Regarding the intake gate 54, if the dam water level exceeds the top of the intake gate 54, the intake gate 54 cannot regulate the waterway water level. Therefore, conventionally, when the dam water level reaches a predetermined intake gate full-closure level L6, the intake gate 54 is fully closed and the settling basin sand flushing gate 56 is fully opened to release water flowing into the settling basin 52 into the river 50. However, if a large amount of sediment flows into the settling basin 52 due to a localized heavy rainfall or other event, the above-mentioned method does not generate a water flow toward the intake gate 54. Therefore, the sediment contained in the water flowing into the settling basin 52 flows into the water conduit 53 along with the water overflowing the training wall 52a before it has time to settle, and accumulates there. Removing this sediment requires the use of heavy machinery, which is time-consuming and expensive. Another problem is that power generation is not possible while the soil and debris is being removed.

[0007] Regarding technology for discharging sediment from a settling basin, for example, Patent Document 1 discloses an invention entitled "Sand Discharge Mechanism" that relates to a mechanism for discharging sand from a settling basin located between the upstream and downstream areas of an intake channel that takes in river water. Using the symbols shown in the drawings of Patent Document 1, Patent Document 1 describes a settling basin 2 provided downstream of a water intake, a sand discharge passage 3 extending outward from the settling basin 2 in a direction intersecting the direction of the main water flow in the settling basin 2 and communicating with the settling basin 2 via an opening 14, a sand discharge gate 15 for opening and closing the opening 14, a step 11 formed by raising a part of the bottom 9 in the most downstream region of the settling basin 2, and a part of the settling basin 2 above the step 11. The sand discharge mechanism is described as having a sand discharge depression 13 located on the flow side and connected to an opening 14 on one side, where a step elevation 12 located at the boundary between the bottom other than the step portion 11 and the bottom 9 of the step portion 11 acts as a barrier to the flow of the main water flow, forming a secondary water flow that flows along this step elevation 12 toward the opening 14, and a water flow left / right deflection device 17 located upstream of the sand discharge depression 13 and capable of deflecting the direction of the main water flow toward the settling basin 2 to the left / right. With this structure, by adjusting the water level in the settling basin so that the bottom of the step is relatively close to the water surface, the step elevation of the step acts as a barrier to the main water flow through the settling basin. Also, if a secondary water flow that flows along this step elevation toward the opening is formed in the sand flushing recess, the water flow deflection device can deflect part of the main water flow toward the sediment, so that the sediment that has accumulated on the bottom of the settling basin on the upstream side is carried to the catchment area of ​​the secondary water flow and carried by the secondary water flow, and by opening the sand flushing gate, the sediment can be reliably discharged from the opening to the outside of the settling basin.

[0008] Furthermore, Patent Document 2 discloses an invention entitled "Sand lifting device for hydroelectric power plants" that relates to a sand lifting device that combines an air-mixing jet pump and a vortex sand flushing pipe. Using the symbols shown in the drawings of Patent Document 2, Patent Document 2 describes a sand lifting device 10 for a hydroelectric power plant, which includes a primary screen 11 provided on the intake side of the intake settling basin, a secondary screen 12 provided on the water conduit side of the intake settling basin, first to sixth vortex sand flushing pipes 21 to 26 provided at the bottom of the intake settling basin, first and second switches 31 and 32 provided in the intake settling basin, first and second jet pumps 41 and 42 provided in the intake settling basin, first and second pressurized water pumps 51 and 52 provided in the intake settling basin, and a sand separation tank 60 provided above the intake. This structure can prevent the intake and water outlet from being blocked by sediment.

[0009] Furthermore, Patent Document 3 discloses an invention entitled "Sand Discharge Device for Water Intake Settling Basin for Hydroelectric Power Generation" that relates to a device for mechanically discharging sediment from the entire surface of a settling basin. Using the symbols shown in the drawings of Patent Document 3, Patent Document 3 describes a sediment discharge device in which a settling basin 1 has an intake channel 2 upstream and a sand discharge channel 7 downstream, the device comprising a plurality of water channels 15a to 15e formed by partitioning the entire surface of the settling basin with partition walls 14 extending along the water flow to the vicinity of the sand discharge channel 7, partition gates 19a to 19e installed at the downstream end of each of the water channels 15a to 15e, a dance sand gate 17 mounted within the water channels 15a to 15e so as to be able to move in the direction of the water flow and which stirs up sediment with the lower end discharge flow caused by the movement, and a dance sand gate traverser 18 which moves the dance sand gate 17 laterally over each of the water channels 15a to 15e. With this structure, sediment from the entire surface of the sedimentation basin can be mechanically discharged, thereby reducing the energy and manpower required for sand removal work. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-6995 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-146603 [Patent Document 3] Japanese Patent Application Publication No. 4-371606 Summary of the Invention [Problem to be solved by the invention]

[0011] The inventions disclosed in Patent Documents 1 to 3 have problems in that the equipment is complicated and requires extensive construction work to install, resulting in the need for a lot of effort and expense to manufacture and install the equipment. Also, when a large amount of sediment flows into the settling basin due to a localized heavy rain, the sediment cannot be efficiently removed.

[0012] The present invention has been made in response to such conventional circumstances, and aims to provide a method for flushing sediment from a settling basin that does not require large-scale construction work and that can efficiently remove accumulated sediment and the like from the settling basin, and a system for flushing sediment from the settling basin to be used therefor. [Means for solving the problem]

[0013] In order to achieve the above object, the first invention provides a method for flushing sand from a settling basin in an intake dam for waterway-type hydroelectric power generation, the method comprising: a water intake provided on a bank facing a river; a settling basin provided downstream of the intake; a settling basin sand flushing gate provided to connect the settling basin to the river; a water conduit provided adjacent to the headrace wall of the settling basin; an intake gate installed in the water conduit downstream of the settling basin; an intake weir provided on the river; and a water level meter installed on the intake weir to detect the dam water level. The method controls the opening and closing operations of the settling basin sand flushing gate and the intake gate based on the dam water level, and is characterized in that when the dam water level reaches the automatic control switch ON level, the opening operation of the settling basin sand flushing gate is initiated and the settling basin sand flushing gate is fully opened before the intake gate is fully closed, and the intake gate is fully closed when the dam water level exceeds the intake gate fully closing level, which is higher than the automatic control switch ON level.

[0014] In the first invention, the grit basin flushing gate is fully opened before the intake gate is fully closed, so that the force of the water flowing into the intake gate, which is not yet fully closed, pushes the sediment accumulated in the grit basin out through the fully open grit basin flushing gate into the river. Also, by fully opening the grit basin flushing gate before the intake gate is fully closed, the timing at which the dam water level reaches the intake gate fully closed is delayed.

[0015] The settling basin sand flushing system of the second invention comprises a water intake provided on a bank facing a river, a settling basin provided downstream of the intake, a settling basin sand flushing gate provided to connect the settling basin to the river, a water conduit provided adjacent to the headrace wall of the settling basin, an intake gate installed in the water conduit downstream of the settling basin, an intake weir provided on the river, a water level meter installed on the intake weir to detect the dam water level, and a gate opening / closing mechanism that controls the opening and closing operations of the settling basin sand flushing gate and the intake gate based on the dam water level, and is characterized in that when the dam water level reaches the automatic control switch ON level, the gate opening / closing mechanism starts the opening operation of the settling basin sand flushing gate and brings the settling basin sand flushing gate to the fully open state before bringing the intake gate to the fully closed state, and brings the intake gate to the fully closed state when the dam water level exceeds the intake gate fully closed level which is higher than the automatic control switch ON level. The second invention is the first invention specified as a product invention, and therefore has the same effect as the first invention. [Effects of the Invention]

[0016] According to the first invention, even if a large amount of sediment flows into the settling basin due to localized heavy rain, the sediment can be efficiently removed from the settling basin. Furthermore, the first invention allows the use of existing facilities, which reduces the costs required for facility installation and maintenance. Furthermore, since the timing at which the dam water level reaches the intake gate full-close level is delayed, an increase in power generation output can be expected.

[0017] The second invention is the first invention specified as a product invention, and therefore has the same effects as the first invention. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing the configuration of a settling basin sand discharge system according to an embodiment of the present invention. [Figure 2] 10 is a flowchart showing the processing procedure of the gate opening and closing mechanism for the sand discharge gate of the settling basin. [Figure 3] 10 is a flowchart showing the processing procedure of the gate opening / closing mechanism for the water intake gate. [Figure 4] (a) is a plan view of a water intake dam for a waterway-type hydroelectric power plant, and (b) is a cross-sectional view showing the structure of the water channel shown in (a). [Figure 5] 10 is a flowchart showing the processing procedure of a dam sand flushing gate opening / closing mechanism for a dam sand flushing gate. [Figure 6] 10 is a flowchart showing the processing procedure of a dam sand flushing gate opening / closing mechanism for a dam sand flushing gate. DETAILED DESCRIPTION OF THE INVENTION

[0019] A settling basin sand flushing system and a settling basin sand flushing method using the same according to an embodiment of the present invention will be specifically described with reference to FIGS. 1 to 3. FIG. [Example]

[0020] Fig. 1 is a block diagram showing the configuration of a settling basin sand flushing system 1 of the present invention. Fig. 2 and Fig. 3 are flowcharts showing the processing procedures of the gate opening and closing mechanisms for the settling basin sand flushing gate 56 and the water intake gate 54, respectively. 4(a) and 4(b), the same reference numerals are used to denote the same components, and their description will be omitted where appropriate. In the following description, the automatic control switch ON level L5 and the automatic control switch OFF level L9 represent the reference water levels at which the automatic control of the settling basin sand flushing gate 56 by the gate opening / closing mechanism 4 is turned ON and OFF, respectively, and the intake gate fully closed level L6 represents the reference water level at which the intake gate 54 is fully closed. Furthermore, the intake gate upper limit level L7 and the intake gate lower limit level L8 represent the intake gate fully closed level L6 plus the dead band water level and the intake gate fully closed level L6 minus the dead band water level, respectively. When the automatic control switch is ON, the gate opening / closing mechanism 4 has the function of selecting either the open operation start mode or the close operation start mode to control the opening / closing operation of the intake gate 54 and the grit discharge gate 56. However, in Figure 2, when the automatic control switch for the grit discharge gate 56 is ON, the gate opening / closing mechanism 4 is always in the open operation mode. Also, in Figure 3, the automatic control switch for the intake gate 54 is always ON. As shown in Figure 1, the intake dam 2, which is the settling basin sand flushing system 1 of the present invention, is equipped with an intake 3 provided in a revetment portion 50a facing a river 50, a settling basin 52 provided downstream of the intake 3, a settling basin sand flushing gate 56 provided in the settling basin 52 so as to connect the river 50 to the river 50, a headrace 53 provided adjacent to the headrace wall 52a of the settling basin 52, an intake gate 54 installed in the headrace 53 downstream of the settling basin 52, an intake weir 58 provided in the river 50, water level gauges 59a and 59b installed in the intake weir 58 and the headrace 53, respectively, and a gate opening / closing mechanism 4 that controls the opening and closing operations of the settling basin sand flushing gate 56 and the intake gate 54 based on the dam water level and waterway water level detected by the water level gauges 59a and 59b, respectively, and the opening / closing status of the dam sand flushing gate 57.

[0021] The opening and closing operations of the grit basin discharge gate 56 and the intake gate 54 will be described with reference to FIGS. 2 and 3. FIG. As shown in Figure 2, if the gate opening / closing mechanism 4 determines in step S1 that the automatic control switch of the settling basin sand discharge gate 56 is ON, it proceeds to processing in step S2, and if it determines in step S2 that the dam water level detected by the water level gauge 59a is below the automatic control switch OFF level L9, it turns OFF the automatic control switch of the settling basin sand discharge gate 56 in step S3 to stop the opening operation of the settling basin sand discharge gate 56, and then returns to processing in step S1. If the gate opening / closing mechanism 4 determines in step S1 that the automatic control switch of the settling basin sand discharge gate 56 is not turned ON, and if it determines in step S2 that the dam water level is not below the automatic control switch OFF level L9, it proceeds to processing of step S4, and if it determines in step S4 that the dam water level detected by the water level meter 59a is above the automatic control switch ON level L5, it proceeds to processing of step S5. Furthermore, if the gate opening / closing mechanism 4 determines in step S5 that the dam sand flushing gate 57 is fully open, it turns on the automatic control switch of the settling basin sand flushing gate 56 in step S6, thereby starting the opening operation of the settling basin sand flushing gate 56. If the gate opening / closing mechanism 4 determines in step S7 that the dam water level is still above the automatic control switch ON level L5, it proceeds to processing in step S8, and if it determines in step S8 that the settling basin sand flushing gate 56 is fully open, it switches control of the settling basin sand flushing gate 56 to manual in step S9 to prevent malfunction, and then returns to processing in step S1. In addition, if the gate opening / closing mechanism 4 determines in step S4 that the dam water level detected by the water level meter 59a does not exceed the automatic control switch ON level L5, if it determines in step S5 that the dam sand discharge gate 57 is not fully open, if it determines in step S7 that the dam water level does not exceed the automatic control switch ON level L5, or if it determines in step S8 that the sedimentation basin sand discharge gate 56 is not fully open, it returns to processing in step S1.

[0022] 3, if the gate opening / closing mechanism 4 determines in step S1 that the dam sand flushing gate 57 is fully open, it proceeds to processing in step S2, and if it determines in step S2 that the dam water level detected by the water level gauge 59a is above the intake gate fully closed level L6, it fully closes the intake gate 54 in step S3. Note that the gate opening / closing mechanism 4 does not proceed to processing in step S2 until the dam sand flushing gate 57 is fully open in step S1.

[0023] If the gate opening / closing mechanism 4 determines in step S2 that the dam water level detected by the water level gauge 59a does not exceed the intake gate fully closed level L6, it proceeds to processing in step S4, and if it determines in step S4 that the waterway water level detected by the water level gauge 59b exceeds the intake gate upper limit level L7, it closes the intake gate 54 by 5 cm in step S5, pauses processing for 3 minutes in step S6, and then returns to processing in step S1. On the other hand, if the gate opening / closing mechanism 4 determines in step S4 that the water channel water level detected by the water level meter 59b does not exceed the intake gate upper limit level L7, it proceeds to the processing of step S7. If the gate opening / closing mechanism 4 determines in step S7 that the intake gate 54 is not fully open, it proceeds to step S8. If the gate opening / closing mechanism 4 determines in step S8 that the water channel water level detected by the water level meter 59b is below the intake gate lower limit level L8, it opens the intake gate 54 by 5 cm in step S9 and then proceeds to the processing of step S6. Furthermore, if the gate opening / closing mechanism 4 determines in step S7 that the intake gate 54 is not fully open, it switches to free flow operation (a state in which the operation of the intake gate 54 is controlled so that the distance between the bottom end of the intake gate 54 and the water surface is kept constant) in step S10, and then returns to the processing of step S1. The gate opening / closing mechanism 4 also returns to the processing of step S1 if it determines that the waterway water level detected by the water level meter 59b is not below the intake gate lower limit level L8.

[0024] As described above, in the settling basin sand flushing method of the present invention, the settling basin sand flushing gate 56 is fully opened before the water intake gate 54 is fully closed, and therefore the force of the water flowing into the water intake gate 54, which is not yet fully closed, pushes the sediment accumulated in the settling basin 52 out of the fully open settling basin sand flushing gate 56 toward the river 50. Therefore, even if a large amount of sediment flows into the settling basin 52 due to a localized heavy rain, the sediment can be efficiently removed from the settling basin 52. Furthermore, the settling basin sand flushing method of the present invention can utilize existing equipment, making it possible to reduce the costs required for equipment installation and maintenance. In addition, the settling basin sand removal system 1 of the present invention is an invention that identifies the components necessary for implementing the settling basin sand removal method described using Figures 2 and 3 as a product invention, and therefore has the same functions and effects as the settling basin sand removal method. [Industrial Applicability]

[0025] INDUSTRIAL APPLICABILITY The present invention can be used to remove sediment and the like that accumulates in a settling basin provided downstream of the intake of an intake dam for a waterway-type hydroelectric power plant. [Explanation of symbols]

[0026] 1...Sand flushing system for settling basin 2...Intake dam 3...Intake 4...Gate opening / closing mechanism 50...River 50a...Bank protection 51...Administration office 52...Sand flushing basin 52a...Training wall 53...Headrace 54...Intake gate 55...Screen 56...Sand flushing gate for settling basin 57...Dam sand flushing gate 58...Intake weir 59a, 59b...Water level gauge L1...Automatic control switch OFF level L2...Automatic control switch ON level L3...Automatic control switch ON upper limit level L4...Automatic control switch ON lower limit level L5...Automatic control switch ON level L6...Intake gate fully closed level L7...Intake gate upper limit level L8...Intake gate lower limit level L9...Automatic control switch OFF level

Claims

1. A method for flushing sand from a water intake dam for a waterway-type hydroelectric power generation system, which includes a water intake provided on a bank facing a river, a grit basin provided downstream of the water intake, a grit basin flushing gate provided in the grit basin so as to connect the grit basin to the river, a headrace provided adjacent to a flow wall of the grit basin, a water intake gate installed in the headrace downstream of the grit basin, an intake weir provided on the river, and a water level meter installed on the intake weir to detect a dam water level, comprises controlling the opening and closing operations of the grit basin flushing gate and the water intake gate based on the dam water level, When the dam water level reaches the automatic control switch ON level, the opening operation of the settling basin sand flushing gate is started, and the settling basin sand flushing gate is fully opened before the intake gate is fully closed, and A method for removing sand from a sedimentation basin, characterized in that the intake gate is fully closed when the dam water level exceeds a fully closed level for the intake gate, which is higher than the ON level of the automatic control switch.

2. A water intake located on the bank facing the river, a settling basin located downstream of the intake; a sedimentation basin discharge gate provided in the sedimentation basin so as to connect the sedimentation basin to the river; a water channel provided adjacent to the water channel wall of the settling basin; an intake gate installed on the water channel downstream of the settling basin; a water intake weir installed on the river; A water level meter installed on this intake weir to detect the dam water level, a gate opening / closing mechanism that controls the opening and closing operations of the sedimentation basin sand flushing gate and the water intake gate based on the dam water level, The gate opening and closing mechanism is When the dam water level reaches the automatic control switch ON level, the opening operation of the settling basin sand flushing gate is started, and the settling basin sand flushing gate is fully opened before the intake gate is fully closed, and A settling basin sand flushing system characterized in that the intake gate is fully closed when the dam water level exceeds a fully closed intake gate level that is higher than the automatic control switch ON level.

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