As important carriers of water resources, deep-water lakes and reservoirs have long faced the dilemma of mismatched investment and effectiveness in ecological management. Practice has shown that the core reason for the failure of traditional management approaches to meet expectations is not a lack of technical capability, but rather the unique characteristics of lake water’s “stratified structure” and “algae behavior,” which make it difficult for single management measures to break through the bottlenecks in the ecosystem.

 

Studies show that in stratified lakes and reservoirs, the effectiveness of conventional management techniques typically lasts no more than two years—far shorter than the 10- to 20-year natural recovery period observed in deep-water lakes and reservoirs, thus creating a vicious cycle of “management—rebound—remanagement.”

Core Challenge: The Dual Constraint of Hierarchical Structure and Endogenous Pollution

The fundamental challenge in managing deep-water lakes and reservoirs lies in their unique ecological structure and pollution mechanisms, specifically manifested as follows:

1. The hierarchical structure hinders the exchange of substances.

Under the influence of temperature and density differences, deep-water lakes and reservoirs develop distinct stratification: the surface layer is a warm-water layer, the middle layer is a thermocline—a zone of dramatic changes in temperature and density—and the bottom layer is the deep-water layer. The thermocline acts like a "barrier," blocking the exchange of substances between the upper and lower water layers. As a result, the bottom water remains chronically oxygen-depleted, and pollutants such as nitrogen and phosphorus stored in sediments—known as internal pollution—continue to be released, making the lake or reservoir a "source of internal pollution" that fuels eutrophication.

 

2. Algal migration exacerbates the complexity of management efforts.

Algae exhibit vertical migration behavior, enabling them to move up and down in the water column by adjusting their gas vesicles, thereby avoiding exposure to surface chemical treatments or aeration. Meanwhile, deep-water algae can easily recover and experience explosive growth under favorable conditions—such as rising temperatures and abundant nutrient availability—making it difficult for conventional surface-based control methods to achieve full water-column coverage.

 

3. Endogenous pollution dominates long-term eutrophication.

Even if external pollution sources—such as point sources and non-point sources—are effectively controlled, the pollutants accumulated in the sediment will continue to be released through processes like diffusion and biotransformation, leading to recurrent eutrophication of lakes and reservoirs and becoming a key factor that makes it difficult to sustain the effectiveness of remediation efforts.

​​

Technological Innovation: A Breakthrough from “Superficial Intervention” to “Systemic Regulation”

In recent years, the approach to managing deep-water lakes and reservoirs has gradually shifted from relying solely on individual technologies to adopting a coordinated management strategy that is “precise, systematic, and ecological.” Core technological innovations are focusing on the following three areas:

1. Ultra-nano aerosol reoxygenation technology: Breaking through stratification limitations and enhancing the oxygenation environment at the bottom layer.

This technology generates ultra-nanoscale bubbles with diameters less than 200 nm. Leveraging their high stability—allowing them to persist for more than 30 days—and their exceptionally high mass-transfer efficiency (reaching up to 90% for gas-liquid mass transfer), these bubbles can penetrate the thermocline and reach directly to the bottom of the lake.

 

Without disrupting the stratification of the water body, this method effectively increases the concentration of dissolved oxygen at the bottom layer and inhibits the release of phosphorus from sediments. Compared to conventional aeration, it boosts oxygen transfer efficiency by more than three times, thereby creating favorable conditions for ecological restoration at the bottom layer.

2. Algae Migration Blocking Technology: Precise Algae Control Across the Entire Water Column

By integrating IoT-based monitoring with intelligent control technologies, we use sensors to continuously monitor parameters such as algal density and chlorophyll a, and combine these data with algorithms to predict the likelihood of algal blooms. Targeting the migratory characteristics of algae, we employ ultrasonic technology to disrupt the gas vesicles in algae, forcing them to rise to the surface. Subsequently, we deploy deep-water slow-release agents to inhibit the regrowth of algae at the bottom layer. This integrated approach—encompassing monitoring, early warning, and targeted intervention—achieves full-process intelligence, significantly enhancing the precision and timeliness of algal control.

​

Successful Practice: The Systemic Governance Experience of Lake Zurich in Switzerland

The governance journey of Lake Zurich in Switzerland (with a maximum depth of 136 meters) provides a model for the restoration of deep-water lake and reservoir systems.

Switzerland, Lake Zurich

In the 1970s, the lake’s phosphorus concentration reached as high as 120 μg/L, with frequent algal blooms occurring during summer and severe degradation of its ecological functions. Through a systematic strategy encompassing “external source control—internal source remediation—ecological regulation,” comprehensive restoration of its ecological functions has been achieved:

·   Exogenous Blocking (1971–1985) Investing 1.5 billion Swiss francs to build a wastewater treatment plant, increasing the phosphorus removal rate to 95% and cutting off external sources of pollution.

·   Endogenous Remediation (1986–2000) Install four deep-water aeration systems in the deep-water zone, with annual operating costs of 2 million Swiss francs, to increase dissolved oxygen levels at the bottom layer and inhibit phosphorus release.

·   Ecological Regulation (2001–Present) Implement ecological fishery management by stocking filter-feeding fish such as silver carp to enhance food-web regulation.

The governance efforts have yielded remarkable results: the phosphorus concentration in the lake has dropped to 12 μg/L, and transparency has increased from 2.5 meters to 10 meters. Cold-water fish species, such as trout, have rebounded to historical levels. The value of ecosystem services has significantly improved—every franc invested in governance generates an ecological and economic return of 4.5 francs.

​

Building a “three-dimensional warfare” system for the governance of deep-water lakes and reservoirs.

The management of deep-water lakes and reservoirs is complex and calls for a shift toward a collaborative governance model that integrates "external sources, internal sources, and biological factors." Practice has shown that only by placing technological innovation at the core, while combining long-term planning with ecological management, can we effectively address stratified pollution, achieve sustained water clarity, and support both aquatic ecosystem conservation and high-quality development.