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A solution for campus flooding challenges and a small-scale demonstration

Chung-Wen Elementary School is located in East District, Chiayi City, an area of intense urban development. The surrounding paved surfaces are extensive, and runoff is highly concentrated. The campus covers approximately 3.8 hectares and has a student population of 1,459, making it one of the most important schools in Chiayi City.

For many years, the open space in front of the preschool and the areas around the building had been major flooding hotspots on campus. Due to the limited capacity of the drainage ditches and the extensive impervious surfaces nearby, heavy rainfall caused large volumes of runoff to overwhelm the drainage system. As a result, overflow frequently occurred around the pavilion area, and water accumulation after rainfall posed safety concerns for both teachers and young students. According to the Water Resources Agency's flood potential map, Chung-Wen Elementary School and its surroundings are in a flood-prone zone, particularly the northern side along Chuiyang Road and Minzu Road, where flooding depths could reach 0.3 to 0.5m. This highlighted the urgent need for the school to enhance its rainwater adaptation and infiltration capacity.

Small-scale rain garden intervention strategy

Given that most of the internal spaces of the school already serve specific functions, the available area for improvement was quite limited. Therefore, a small-scale, low-impact strategy was adopted. By slightly adjusting the plant nursery area and introducing a rain garden system, the existing space was upgraded into a sustainable site with water retention and flood mitigation functions.

Design highlights:

1. Rainwater source consolidation: rainwater from the roof of the indoor baseball field is diverted via interception pipes to infiltrate into the rain garden.
2. Multi-facility integration: the system includes the rain garden, permeable concrete pavement, underground water storage tank, and a lawn filtration buffer zone.
3. Uninterrupted traffic flow: the long jump pit and maintenance vehicle path remain functional as the rain garden is placed next to the area and separated with a green belt.
4. Subsurface pipe connectivity: overflow from the garden is directed into an underground water storage system beneath the maintenance vehicle path, reducing surface runoff pressure.

The overall configuration balances safety and functionality, creating an environmental education space on campus with rainwater adaptation, ecological teaching, and aesthetic landscape qualities.

Renovation highlights: integrating greenery with water circulation

Although Chung-Wen Elementary School's rain garden project is a small-scale demonstration, its effectiveness is particularly remarkable. Through simple and impactful design, a corner of campus that was once a burden to the school’s drainage system was successfully transformed into a multifunctional landscape space capable of rainwater retention, infiltration, and reuse. After completion, post-rain flooding was significantly reduced, easing pressure on the drainage system and improving overall flood control efficiency. Runoff from buildings and pavement is no longer merely discharged wastewater but is redirected into the garden and underground storage system for reuse, achieving the goal of rainwater resource utilization.

Plants selected for the garden are low-maintenance and drought-tolerant, greatly reducing the need for frequent upkeep in the future. Combined with permeable pavement, the design also mitigates the urban heat island effect common in hard-paved areas. The overall design not only improves spatial functionality but also incorporates educational significance, enabling students to observe the full process of rainwater collection, infiltration, storage, and reuse, experiencing the value of water resource circulation in their daily lives.