JPS61162612A - Method and device of preventing sinking of city due to raising of water level - Google Patents

Abstract

PURPOSE:To prevent a city from being sunk under water, by a method wherein a bay is separated into a reservoir having a low water level and a bay, connected to the open sea having a raised sea surface, by an undersea dam, and water in the resevoir is drained with the aid of a pump. CONSTITUTION:A bay, being adjacent to a city 3, is separated into a reservoir 7, having a low water level, and a bay 2, connected to the open sea 1 having a raised sea surface, by means of a rock-fill dam 4 and a concrete dam 5. A pump water turbine 20 is installed on the bottom of the concrete dam 5. When a water level in the reservoir 7 is increased to a specified level, water is drained through the running of the pump water turbine 20, and the water level in the reservoir 7 is maintained at a state before raising of the sea surface.

Description

[Detailed description of the invention] (a) Industrial application field This invention is a method and device for preventing urban flooding that combines drainage of a reservoir using a pump-turbine built into an underwater dam, pumped storage power generation, and tidal power generation. in between.

(b) Conventional technology The burning of large amounts of fossil fuels in the 20th century increased carbon dioxide in the atmosphere, causing a global greenhouse effect that caused the global temperature to rise and melt the ice in Antarctica.
It is predicted that the sea level will rise by approximately 6 meters from around 2013 to 2040 (announcement by the U.S. Department of Strategic Environment, published in a major Japanese newspaper on October 18, 1983).
As a result, a huge amount of coastal land will be submerged.

Traditionally, in order to create a country that is below sea level, the Netherlands used a method of constructing embankments on the coast and pumping water accumulated on the land to the open sea.

(c) Problems that the invention aims to solveHowever, there are heavy rains caused by typhoons, etc. ! In sea cities, the amount of water discharged is very large, so the impeller diameter is 5 mm for drainage pumps.
Since it is necessary to use many large axial flow pumps with a diameter of 1 to 9 meters, a location with a water depth of 15 to 30 meters is required for installing the pumps, which makes it difficult to install the pumps on land as described in (b) above. Therefore, an underwater dam will be built offshore to isolate the city from the open sea, and the pump will be installed at the bottom of the dam to drain water from the reservoir inside the dam and control the water level in the reservoir at will.

The drainage capacity of the pump will be approximately four times the maximum inflow 1 (m3/s) into the reservoir that occurs once every 30 years, and will have the capacity to drain even a flood that occurs once every 10,000 years.

However, in normal weather, most of the pumps, which have a capacity of KW to several million KW, must be stopped, which is uneconomical. Therefore, when rainfall is low, the pumps are operated at full capacity using surplus electricity at night to lower the water level in the reservoir, and during peak hours during the day the head difference between the open ocean and the reservoir is used to generate electricity. By using it as a pumped storage power plant, the aim is to prevent cities from being submerged due to rising sea levels and to reduce the uneconomical costs of the enormous capital investment required.

(d) Means for Solving Problems To explain this invention based on drawings, in FIG.
If the water level of the open ocean 1 rises by 6 m, most of the city 3 will be submerged. Find or build high ground with an altitude of 6 m or more on both banks 9 of 812, and connect the bay 2 to both highlands 9. It is divided into two by underwater dams A and 6, and the bay inside the dam is called reservoir 7. Dam 4 is a rockfill dam, and dam 6 is a concrete dam with a built-in pump turbine 20 at its bottom.
A ship lock 6 is installed in the dam 4, and land water flowing into the reservoir 7 is mainly from a river 8.

The water levels of the reservoirs 7 and 112 are shown in FIG. 2 as heights from the reference surface 10 of the water depth before the water level of the open ocean 1 rises. Set water level 15 of reservoir 7 (hereinafter referred to as H, W, L)
,) is set to the average tide level before sea level rise, and lower than this by the available water depth of the reservoir, low water level 16 (hereinafter referred to as tidal level) is set to the average tide level before sea level rise.
(referred to as W and L). H, W, L, 15 and
L, W, L.

The average water levels 17 of 16 are hereinafter referred to as M, W, and L.

Reference surface 1.1 for water depth after sea level rise in Bay 2 is the old reference surface 1.
6m higher than 0. High tide level 12 and low tide level 1 of 1II2
3 and the new standard surface of average tide level 14! The height from 1 is the same as the value of the tide table before sea level rise.

In a sea with no tidal difference, the reference plane io of reservoir 7 is HoW, L
, 15, and the tide level 12.13.14 of the bay 2 coincides with the reference plane 11.

Concrete dam 6 connects bay 2 from city 3 to open ocean l.
Of the bottom gradient 18.19, the water depth from the reference surface 10 is
It is installed on the seabed 18 about three to four times the diameter of the impeller 21 of the pump-turbine 20.

The impeller 21 of the pump turbine is coupled to a DC motor generator,
Variable speed DC operation is performed from an AC power source via an AC/DC converter. This is not due to sudden sea level rise;
This is because the rise is about 10-odd degrees per year, so it is necessary to accommodate the wide range of changes in head and head after the pump-turbine is installed.

(E) Effect FIG. 4 is a graph showing changes in the water level in the reservoir 7 and the bay 2 during a day when the inflow of the river 8 into the reservoir 7 is sufficiently small compared to the flow rate of the pump.

The horizontal axis XZ is a time axis, and the vertical axis XC is the height of the water level from the reference surface 10. xz is 24 hours, and xY and YZ are each 12 hours. If X is 21.00 hours, Y is 9
．． 00 o'clock tyz is 21.00 o'clock. The tide level of 112 is indicated by CDEFGI (IJKLM) and is photographed above and below the mean tide level 14. The water level of reservoir 7 is indicated by N0PQRST, and No and ST correspond to H, W, L, 15. Arrow 24 is the pump The arrow 26 shows the head of the water turbine.The pump 20 starts operation at OE height at 6:00 o'clock the next morning, and ends at PG head at 6:00 o'clock the next morning.During the 6-hour leap night, the pump 20 starts operating at OE head. So, the water level of reservoir 7 is H, W, L.
, 15, go down to W, L, 16. At this time, the water level of reservoir 7 is rising, W, L.

16, the pump is automatically stopped.The water turbine 20 can be operated continuously at any time between 9:00 and 21:00.For example, as shown in Figure 4. At 12:00, the operation starts with head JR and ends with head LS at ts and oo. At this time, when the water level of the reservoir 7 reaches H6W, L, 15, the water turbine is automatically stopped.Using the automatic stop device of the pump water turbine, .

A method is used to improve urban drainage by setting W, L, and 1B even lower. Similarly, H, W, L, Tori.

By setting W and L arbitrarily, the water level of the reservoir can be controlled.

Area Am and water usage ti at average water level 17 of reservoir 7
Bm (NO in FIG. 4) is determined as follows.

Maximum inflow Q from river 8 to reservoir 7 once every 30 years.

-/8 (hereinafter referred to as standard inflow rate) continues for 18 times and the water level in reservoir 7 rises by 8 m, the total water volume per day is A.
Since xBm3, AXB=%X24X3800
[11 If A is specified, B=%X24X3600/A [2] Find B. Generally speaking, the value of B should be 2 m or less for environmental reasons.If the standard flow rate of the pump is Qpm/s, 6 hours of pump operation drains A x B m3 of water, so Q=AXB/(6X3600) [3 ].

In order to find the total power of the pump-turbine, the standard head of the pump, m (=6+B/2), is determined as follows.

L=Water pump total power MW (= 106Nms-1>
Q = water pump standard total flow rate m/s γ = specific weight of seawater = 1.03X9806 = 10100
N/m = standard efficiency of the pump, η, = standard efficiency of the water wheel, = to x % x r/(η, x 1♂) It is assumed to be the same as power. The operating time of the water turbine at full power is approximately 6Xy when Q0 = 0.
It will be 41 hours. To obtain longer power generation time,
It would be better to reduce the total output by reducing the number of water turbines in operation.

When the inflow to the reservoir 7 is equal to the standard inflow, the pump will operate normally for 6 hours, but the turbine will not operate.If the inflow is less than that, the inflow will be subtracted from the pump displacement. The water turbine is operated to generate electricity based on the amount of water.

When the inflow rate is higher than the standard inflow rate, the water turbine is not operated at all, the pump operating time is increased, and the pump is operated all day to the maximum, thereby discharging approximately four times the standard inflow rate. I can do it.

Next, as an energy-efficient operation method, in Fig. 4, during the night (XY), the leap pump operation is performed during the negative half cycle of the tide level DEF, and during the daytime (YZ), during the positive half cycle of the tide level H1 and KLM. When operating a water turbine, the pump head is small and the head of the water turbine is large to transport the same amount of water, making it possible to increase the efficiency of seed water power generation.

FIG. 5 shows that by adding an artificial island 26 or an artificial peninsula 27 to part or all of the dam 4, it is possible to not only increase the strength of the dam 4 against earthquakes and waves, but also to increase the
$1! It can be used as a bay and land for nuclear power plants, etc. In addition, the motorway 28 will be built at the top of the dam 4.5, and will be used as a bayside bypass road to facilitate transportation.

In addition, in cities 3 that do not have 1!2 and have a straight coast 29, the dam 4 should be bent into a U-shape to the coast, or the artificial peninsula 3
0.31 can be created to create an artificial bay to achieve the same purpose.

(F) Example Tokyo is in a state where most of it will be submerged due to a 6m sea level rise, so in order to avoid this, a line of 15km above the current sea level connecting Kawasakifu in the center of Tokyo Bay and the northern suburbs of Kisarazu City will be constructed. Dam 4.
Closes at 6. At this time, the area of reservoir 7 is A = 56
0 km2 and the maximum water depth at the dam location is 3
0m, and the standard inflow rate is %=10000m/s. The available water depth of the reservoir is based on formula [2].

B= 10X24X3600/ (560X I 0)
=1.54m<2m Since it can be changed, here B=
The length shall be 1.6m.

The standard flow rate of the pump is 41480 m/s from formula [3].The total power of the pump is 0.8 the standard efficiency of the pump.
Then, from formula [4], = 6.8X41480X 10100/ (0°8
X 106) = 3560MW It is the same as the total power Lt of the water turbine. Dam 6 has 137 axial flow pump turbines each with an impeller diameter of 8 m and a capacity of 26 MW.
Set up a stand. At this time, the total length of Dam 5 is approximately 2.5 km.
The total length of the dam is approximately 12.5km.

Conventionally, when high tides such as typhoons occur during high tides, flooded areas occur in the Tokyo area, but with this invention, the water level in the reservoir can be lowered at will, so there is no need to worry about this.

Tokyo Port could be moved to the open ocean side of the artificial island, and Haneda Airport could remain as is, but it could also be relocated as a sea airport on the artificial island.

(g) Effects of the Invention As explained above, this invention is a dam built offshore of a coastal city that is expected to be submerged due to rising sea levels, and a pump built into the dam that separates the reservoir adjacent to the city from the open ocean. The drainage function of the water turbines will keep the water level in the reservoir below the high tide level before sea level rise, preventing the city from being submerged.

By increasing the drainage capacity of the pump to four times the standard inflow into the reservoir, any amount of precipitation can be safely drained.

Therefore, in normal weather, there is sufficient drainage equipment, so it can be used as a pumped storage power plant with the open ocean serving as the upper reservoir and the reservoir serving as the lower reservoir.

An artificial island can be added to a part of a dam to increase the strength of the dam against earthquakes, waves, etc., and a floating city, airport, nuclear power plant, etc. can be built on it.

A motorway can be built on top of the dam to serve as a maritime bypass road.

[Brief explanation of the drawing]

Figure 1 shows the relationship between dams and open oceans, bays, cities and reservoirs.
Figure 2 is a plan view showing the relationship between the water levels on both sides of the dam, Figure 3 is a side view of the pump-turbine, and Figure 4 shows the operational status of the pump-turbine for one day and the relationship between the water levels on both sides of the dam. A temporarily closed water level curve diagram showing changes in water level, and FIG. 6 is a plan view showing an artificial island. l...open ocean, 2...bay, 3...,φ city, 4 fists...rockfill dam, 5...concrete dam,
7◆...reservoir, 8...φ reservoir inflow river, lO
・φ・Water level reference plane, 14... Average tide level of the bay, 1
5... High water level of the reservoir, 20... Pump turbine,
26... Kushi artificial island, 30... artificial peninsula,

Claims (1)

[Claims] 1. The bay bordering the city (3) is constructed by underwater dams (4) and (5).
dams (5), which are separated into a reservoir (7) with a low water level and a bay (2) connected to the open ocean (1) with rising sea levels.
A method for preventing urban submergence due to sea level rise, characterized in that a pump (20) is installed at the bottom of the water reservoir (7) to drain water from the reservoir (7), thereby maintaining the sea water level of the city and the reservoir at the state before sea level rise. 2. A patent for using a pump as both a pump and a water wheel, using the reservoir as a lower reservoir and the open ocean as an upper reservoir, pumping water from the reservoir to the open ocean at night, and using the head difference between the open ocean and the reservoir during the day to generate electricity with the water turbine. Pumped storage power generation device 3 in the method for preventing urban submergence according to claim 1.Pumped storage power generation device 3 in the method for preventing urban submergence according to claim 1.A claim that the pump is operated when the tide level of the open ocean is below the average tide level, and the water turbine is operated when the tide level of the open ocean is also above the average tide level. Method 4 of operating a pumped storage power generation device in the method for preventing urban submergence described in Sections 1 and 2: When the water level of the reservoir is L. W. L. (
16), the pump automatically stops and the H. W
．． L. (15), the water wheel automatically stops and the reservoir's H. W. L. and L. W. L.
Reservoir water level control method 5 in the method for preventing urban submergence according to claims 1 to 3, in which the water level on the coast of the reservoir is controlled by arbitrarily changing the water level of the reservoir. Artificial peninsula (27
) is added to increase the strength of the dam against earthquakes or waves. 6 Subsea dam reinforcement method in the method for preventing urban submergence according to claim 1. An artificial peninsula ( 30), (3
1) and connects dams (4) and (5) to the tips thereof to create an artificial bay (7).