Climate Risk Adaptation Project: Wave-Actuated Upwelling Pump for Coastal Surface-Water Management

Using wave energy to improve near-surface conditions in coastal and aquaculture waters

The Wave-Actuated Upwelling Pump is a small, distributed seawater-circulation device that uses the vertical motion of waves and a check valve to move water from a selected depth toward the upper layer.

The intake depth is selected from local observations rather than fixed in advance. The system requires no external electricity or fuel during operation. NPO ESCOT is investigating its potential to mitigate excessive near-surface water temperatures and improve environmental conditions in coastal and aquaculture waters.

This is not a completed intervention that can improve an entire water body simply by being installed. Before deployment, water temperature, dissolved oxygen (DO), salinity, chlorophyll, turbidity, waves, water depth, currents and aquaculture practices must be examined. The intake depth and discharge position must then be selected, and the effects and possible impacts must be evaluated against a control area.

[Insert main illustration: Improvement of near-surface conditions using a Wave-Actuated Upwelling Pump]

What has been confirmed and what is still being tested

Confirmed to date	Under field evaluation
Wave motion and the check valve can move water upward through the pipe.	The area over which cooling may occur and the duration of any effect.
Pumped volume per cycle changes with the vertical-motion period and other operating conditions.	Effects on the survival and growth of cultured organisms.
Temperature differences between the near-surface layer and water several metres below have been observed at Onjuku and other locations.	Effects on DO, nutrients, plankton and other water-quality or ecological variables.
In an Ise Bay analysis, the layer around 5 m was cooler than the surface while retaining a certain level of DO during the study period.	Effective spacing, area of influence and operating methods for multiple units.
No external electricity or fuel is required during operation.	Biofouling, durability, maintenance frequency and possible fish-aggregation effects.

1. Basic configuration and operating principle

The device consists primarily of:

a round buoy;
a check valve;
an upper upwelling pipe;
a lower upwelling pipe;
mooring lines; and
cleaning ropes or other maintenance components.

The detailed configuration is adjusted to the local wave climate, water depth, mooring conditions and intended intake depth.

Pumping cycle

As a wave lifts the buoy and upwelling pipe, the upper check valve closes and the water inside the pipe is lifted with the pipe.
Near the crest of the wave, the upward movement of the device slows or stops. The inertia of the water inside the pipe opens the check valve and discharge toward the upper layer begins.
As the device descends, the water inside the pipe continues moving upward and is discharged through the angled valve opening.
Near the trough of the wave, the flow weakens, the valve closes and the cycle begins again with the next wave.

[Insert pumping-principle diagram]

Important terminology: “lower-layer water” on this page does not mean deep ocean water. The target is a shallow or intermediate layer selected after confirming its temperature, DO and other local conditions.

2. Intake depth must not be selected by temperature alone

In artificial upwelling, the coldest available water is not necessarily the safest or most appropriate water to move upward.

Deeper water may be cold but depleted in oxygen. Transporting such water into the upper layer or into the depth occupied by cultured organisms could adversely affect marine life.

ESCOT therefore evaluates temperature together with DO, chlorophyll, salinity, turbidity and other relevant variables. We use the working term Healthy Cooling Water Layer (HCWL) for a layer that is cooler than the surface while retaining environmental conditions considered suitable for the intended application.

HCWL is not a fixed depth. It may change with location, season, time of day, stratification and weather or oceanographic conditions.

Example: central Ise Bay data

NPO ESCOT analysed central Ise Bay monitoring data supplied by the Chubu Regional Development Bureau of Japan’s Ministry of Land, Infrastructure, Transport and Tourism.

For July 2025, the mean temperature at 5 m was approximately 4.5°C lower than at 0.1 m, while mean DO at 5 m was 6.85 mg/L. DO declined at 10 m and below, illustrating why intake water should not be selected simply by choosing the deepest or coldest layer.

Depth	Mean temperature	Mean DO	Interpretation for intake selection
0.1 m	27.57°C	7.64 mg/L	Near-surface layer prone to heating
5 m	23.07°C	6.85 mg/L	HCWL candidate during this study period
10 m	21.36°C	5.11 mg/L	Cooler, but declining DO requires caution
15 m	20.93°C	4.47 mg/L	Risk associated with moving low-DO water

These values apply only to the central Ise Bay dataset and period analysed. They must not be transferred directly to another sea area.

[Insert Ise Bay temperature and DO graph]

3. Laboratory and field evaluation

Small-scale pumping tests

Tests conducted under different vertical-motion conditions showed that pumped volume per cycle changes with the motion period. Shorter periods and higher acceleration do not necessarily produce greater pumping in every case.

ESCOT is continuing to examine relationships among flow rate, period, amplitude, pipe diameter, check-valve geometry and local wave conditions so that device specifications can be matched to each site.

Iwawada Fishing Port, Onjuku, Chiba Prefecture

At Iwawada Fishing Port, ESCOT continues to examine:

vertical water-temperature differences from the near-surface layer to several metres below;
device durability;
biofouling;
maintenance requirements; and
practical operation in a working fishing port.

Observed temperature differences vary with time and sea conditions. Results must therefore be evaluated using both mean values and variability rather than isolated maximum differences.

[Insert photographs: Iwawada field testing and vertical temperature observation]

Potential use in aquaculture waters

For scallops, oysters, nori seaweed and other cultured species, high temperature is only one consideration. A field assessment should also include DO, salinity, chlorophyll, current direction and velocity, culture depth, equipment layout and workability.

ESCOT recommends beginning with a small comparative trial and a control area. The number and arrangement of units should be considered only after the measured differences and possible impacts have been evaluated.

4. Research presentations and international collaboration

In June 2026, ESCOT presented the HCWL concept and intake-depth analysis based on central Ise Bay data at GHRSST27, held at Hokkaido University in Sapporo, Japan. The work was introduced through a poster pitch and poster presentation.

The presentation did not claim that the device’s environmental improvement effects had already been demonstrated. It proposed a method for selecting a safer intake layer and a framework for future field evaluation.

Other activities include field testing at Onjuku, studies relating to aquaculture waters, presentations to academic and technical audiences, and exchanges with researchers and organizations in Japan and overseas.

5. Potential applications and present evaluation stage

Potential application	Present stage	Appropriate statement
Mitigation of excessive near-surface water temperature	Field evaluation	Measure the affected area and duration of any temperature change.
High-temperature risk in aquaculture	Pilot planning and comparative trials	Test effects on survival, growth and production conditions.
Stratification and DO conditions	Observation and analysis	Observe changes without assuming that DO will improve.
Biofouling and possible fish-aggregation effects	Investigative hypothesis	Record attachment and fish use around the structure.
Nutrients and wider ecological effects	Research hypothesis	Evaluate with water-quality and biological data.
Evaporation, CO₂ uptake and meteorological effects	Long-term research hypotheses	Do not present these as established primary effects. Evaluate separately with appropriate observations and models.

Statements that should be avoided

The intake depth is not universally fixed at 5 m.
The device is not designed simply to pump the deepest or coldest available water.
Installation alone does not guarantee improvement in DO, nutrient conditions, fish catch or aquaculture production.
Performance depends on waves, stratification, currents, discharge position, number and spacing of units, and site characteristics.
Although the device needs no electricity or fuel during operation, fabrication, installation, mooring, inspection and cleaning are still required.
Effects on extreme heat, heavy rainfall, typhoons, evaporation or oceanic CO₂ uptake have not been established. These remain topics for longer-term interdisciplinary research.

6. Recommended pathway for a field pilot

Initial site review
Confirm the environmental problem, aquaculture or fishing practices, navigation, operations and management capacity.
Vertical observations
Measure temperature, DO, salinity, chlorophyll and other relevant variables from the surface to the candidate intake depth.
Specification and deployment design
Select the intake depth, discharge position, pipe diameter and length, buoy, mooring method and monitoring plan.
Small-scale comparative trial
As a general starting point, deploy one to three units and establish a suitable control area.
Measurement and evaluation
Record temperature, DO, pumped flow, affected area, durability, biofouling, maintenance and workability. Add biological variables appropriate to the target species or ecosystem.
Joint review and next-stage decision
Share the results and jointly decide whether to continue, modify, expand or discontinue the trial.

7. Frequently asked questions

Is the intake depth always 5 m?

No. Five metres was an HCWL candidate in one Ise Bay analysis. The intake depth must be selected from the local vertical profiles of temperature, DO and other relevant variables.

Will installation automatically increase dissolved oxygen?

No general increase can currently be claimed. The outcome depends on the DO of the intake water, stratification, currents, air–sea exchange and discharge conditions. Measurements before and after installation, together with a control area, are required.

Does the device require electricity?

No external electricity or fuel is required during operation. However, manufacturing, deployment, mooring, inspection and maintenance require materials, labour and appropriate marine operations.

Can one unit lower the temperature of an entire bay or aquaculture area?

No such claim can currently be made. The area and duration of any temperature change must be measured under local wave and current conditions. Multiple-unit arrangements should be considered only after small-scale testing.

Can the device prevent typhoons, heavy rain or extreme heat?

This has not been demonstrated. Possible connections among sea-surface thermal conditions, evaporation and coastal weather are long-term research questions requiring atmospheric and oceanographic observations and numerical modelling.

Does artificial upwelling always benefit ecosystems?

No. Moving low-DO or otherwise unsuitable water upward may cause adverse effects. Safe intake-depth selection and monitoring are essential.

8. Research and pilot partners wanted

The Wave-Actuated Upwelling Pump requires expertise from multiple fields, including oceanography, fisheries science, meteorology, fluid mechanics, thermal engineering, environmental measurement, numerical modelling and marine operations.

NPO ESCOT welcomes discussions with:

universities and research institutes;
fishing cooperatives and aquaculture operators;
national and local government agencies;
marine engineering and environmental-monitoring companies;
port and coastal managers; and
organizations interested in climate adaptation and coastal resilience.

Potential partners are invited to work with us on scientifically designed pilot projects that begin with local observations, use appropriate control sites and evaluate both benefits and possible adverse effects.

Contact NPO ESCOT to discuss a candidate sea area, aquaculture site or joint research project.

9. Related information

Japanese main page: 波動式湧昇ポンプ
NPO ESCOT contact page: Contact & Access
GHRSST27 report and related field-test materials: add the corresponding English or bilingual links from the Japanese page.
Videos and technical documents: retain only materials that match the current device specification and evaluation status.

Recommended WordPress settings

Page title: Climate Risk Adaptation Project: Wave-Actuated Upwelling Pump for Coastal Surface-Water Management
Short menu label: Wave-Actuated Upwelling Pump
New slug: wave-actuated-upwelling-pump-en
Meta description: NPO ESCOT is evaluating a wave-actuated upwelling pump that uses wave motion to move locally selected cooler water toward the upper layer without external power, with careful intake-depth selection based on temperature, dissolved oxygen and field observations.
Focus keyphrase: Wave-Actuated Upwelling Pump
Suggested tags: Climate Risk Adaptation; Coastal Water Management; Aquaculture; Artificial Upwelling; HCWL

Recommended publication and redirect procedure

Open the existing English fixed page at /wave-actuated-upwelling-pump-2/ in WordPress.
Replace its old body text with this revised English draft. Retain only current photographs, diagrams and links.
Change the page slug to wave-actuated-upwelling-pump-en.
Publish or update the page and confirm that the new URL opens correctly.
Create a permanent 301 redirect from:
- /wave-actuated-upwelling-pump-2/
- to /wave-actuated-upwelling-pump-en/
Update the English menu and the Japanese page’s English-language link to the new URL.
Add reciprocal language links near the top of both pages:
- English page: 日本語版はこちら
- Japanese page: English version here
Test both the old and new URLs in a private browser window. The old URL should redirect once to the new page without a loop.

Caution: Do not delete the old fixed page before the redirect and the new URL have been verified. Changing the slug on the existing page may cause WordPress to create an automatic redirect, but this should be tested rather than assumed.

Editorial replacement checklist

Remove from the old English page any wording that presents the following as established effects:

typhoon or heavy-rain control;
mitigation of coastal extreme heat;
increased oxygen or CO₂ absorption;
increased phytoplankton or food production;
a universally fixed 3–6 m intake depth;
guaranteed fish-aggregation or payao effects;
outdated prices and component dimensions; and
royalty-free or open-technology terms that are inconsistent with the current intellectual-property and project policy.