When a torrential downpour strikes the city, and your home already has a large-scale central treatment plant in the distance—though one that’s clearly operating at full capacity—do you really still want several more sewage treatment plants to suddenly appear out of thin air, just to quickly handle the floodwaters?

 

The decentralized intercepting and drainage system is precisely the “natural” treatment plant that descends from the sky. It embodies a modern water management philosophy characterized by "breaking down the whole into smaller parts, addressing issues at their source, and enabling intelligent interconnection," and it boasts distinct features and outstanding advantages.

Feature 1: Precise targeting, source control

Unlike the traditional “collection—long-distance transportation—centralized treatment” model, a decentralized system divides the city into several small drainage districts.

 

Set moderately sized detention and storage ponds at key nodes in each subdistrict—such as outlets—to address stormwater issues “on-site.” This is akin to having fire stations stationed in every community rather than concentrating all fire trucks in the city center, thereby greatly enhancing response speed.

Feature 2: Modular assembly, flexible and efficient

System core — regulating and storage pond — adopts a modular structure (such as a steel structure). This means:

Fast construction:   Prefabricated at the factory and assembled on-site like “building blocks,” this method can shorten construction time by more than 50% compared to traditional concrete pools.

Highly adaptable: In hilly, mountainous, or urban areas where land is extremely scarce, “seize every available space”—such as corner plots, underground green spaces, and underground parking lots—can be utilized to address the challenge of “having no place to build a reservoir.”

Easy to scale: Does urban development lead to increased traffic? In the future, we’ll be able to easily add new modules—just like adding a hard drive—to scale up capacity.

Feature 3: Economical and practical, with low overall costs.

Although individual detention and storage ponds are dispersed, they are more cost-effective when viewed from the perspective of the system’s entire life cycle:

Save substantial pipeline investment: Avoided the construction of large-scale, long-distance collection pipelines.

Reduce land acquisition and relocation costs: A single pond occupies a small footprint, offers flexible site selection, and significantly reduces the difficulty and cost of land acquisition.

Reduce operational energy consumption: Rainwater is stored and treated locally, reducing the energy consumption associated with long-distance water transport by pumping stations.

 

Feature 4: Green and Low-Carbon, Resource Circulation

Decentralized systems are the perfect embodiment of the “sponge city” concept.

Emission reduction and flood prevention: Effectively control combined sewer overflow (CSO) pollution, significantly reduce peak flow rates, and prevent urban flooding.

Rainwater reuse: Collected rainwater is a valuable resource that, after simple treatment, can be used for irrigation, car washing, toilet flushing, and other purposes, thereby promoting water resource recycling and reducing the consumption of tap water.

Environmentally friendly: The construction process is environmentally friendly and causes minimal disruption to the community.

Success Story: The “Resilience” Initiative in Guangming District, Shenzhen

As a national pilot zone for sponge city construction, Guangming District in Shenzhen is exploring a PPP-based construction and operation model that integrates plants and networks. Following the planning recommendation that at least 400 cubic meters of stormwater storage capacity should be provided for every 10,000 square meters of hardened surface area, the district has carried out large-scale deployment of decentralized drainage systems.

 

During Typhoon “Tali” in 2023, the system withstood extreme rainfall without causing significant urban flooding. The key to its success lies in strengthening infrastructure resilience, conducting research on technologies related to “dual-use” stormwater storage facilities that can serve both normal and emergency situations, and coordinating above-ground, underground, and lake-based stormwater storage spaces to maximize the multifunctional use of urban space and enhance the resilience of the city’s drainage system.

The decentralized stormwater management system is not merely a simple rejection of traditional approaches; rather, it represents an upgrade in conceptual thinking and a technological innovation. It makes urban drainage systems more resilient, smarter, and more sustainable, serving as the cornerstone for building future resilient cities that can effectively cope with the challenges posed by climate change.