Flood Risk and CO₂ Mitigation: Analysis of Climate Change Response of Greening Vacant Houses in Old Downtown Metropolitan Areas

While greening vacant houses is encouraged as a sustainable strategy, there is a paucity of quantitative research on its effects. The purpose of this study is to evaluate the flood risk and CO2 mitigation effects of greening neglected vacant houses and barren sites in densely built old downtown areas. To achieve this goal, an investigation was conducted of the actual conditions of vacant houses and barren sites in Ami-dong and Chojang-dong in Busan Metropolitan City. Subsequently, four scenarios for greening vacant houses and barren sites were developed, and rainfall runoff simulations were performed using the K-LIDM model. Furthermore, the annual CO2 fixation for greening with trees was calculated using established research formulas. This study found that 73% of vacant houses in the study area remain unoccupied for an extended period, and when demolished, 56% become concrete-paved barren sites. The runoff simulations indicated that greening with trees led to a 1.71% decrease in annual runoff volume in the long-term model, with peak runoff volume reductions of 3.06% and 2.38% during 2-year and 30-year rainfall events in the short-term model, respectively. Planting trees could accommodate 3058 trees, fixing 62,124 kg of CO2 annually. This study demonstrates the climate change response effects of greening vacant houses.