Kaohsiung Flood Damage Minimal Despite Record Rainfall; Retention Ponds Credited

Kaohsiung, Taiwan, weathered a severe rainstorm that brought over 900 millimeters of cumulative rainfall, surpassing records set by major typhoons, yet the city center experienced only minor damage. The effectiveness of the city's flood retention systems was widely praised on social media.

In the "Kaohsiung Hao Guori" (Kaohsiung Good Days) Facebook group, residents shared observations of the Zheng Yi Park micro-retention pond. Reports indicated the pond neared capacity during the early morning downpour but had drained to normal levels by midday as the rain subsided. This "peak shaving" function of retention ponds is crucial for preventing urban flooding by storing sudden runoff and releasing it gradually.

The area around Zheng Yi Park, historically prone to flooding due to its location at the confluence of the Ai River and Fengshan River drainage systems and receiving overflow from Chengcing Lake, has seen significant improvements. While a previous flood retention pond existed, it occasionally overflowed. In recent years, the Water Resources Bureau has added several micro-retention ponds, including Zheng Yi Park, which was excavated an additional 2 meters to hold 8,000 tons of water. These interconnected ponds have proven effective during recent heavy rains.

Despite a considerably smaller flood control budget compared to Taipei, Kaohsiung has made substantial investments in flood mitigation. Starting with former Mayor Hsieh Chang-ting, the city used some of its own funds to build retention ponds. Under current Mayor Chen Chi-mai, an additional 11 ponds have been constructed, increasing the city's total flood retention capacity by approximately 1.26 million tons to a total of 5.78 million tons. Upgrades to drainage systems in areas like Renwu and Daliao, following a major typhoon two years ago, also operated effectively during the recent storm.

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The Zheng Yi Park micro-retention pond. Reports indicated the pond neared capacity during the early morning downpour but had drained to normal levels by midday as the rain subsided. This 'peak shaving' function of retention ponds is crucial for preventing urban flooding by storing sudden runoff and releasing it gradually.