The increased frequency of extreme rain events due to climate change has garnered attention in Japan. In 2018, the country enacted the Act of Climate Change Adaptation to formulate plans at national and local levels. The government has suggested the use of nature-based solutions (NBSs) across the country to address the increased risk of natural disasters. This study employs scenario analysis to examine the effectiveness of NBSs for the mitigation of flood risk and their implications on the provision of ecosystem services (ESs). Shiga prefecture in Japan enacted its own ordinance in 2015. This ordinance considers existing land use and building regulations to mitigate flood risk. The quantitative analysis assumes nine scenarios up to the year 2050, combining the current policy of Shiga and our original assumption of advance policy options to evaluate the future flood risk and ES. The analysis revealed that land use management can partially mitigate the flood risk by banning new residences and relocating residential land from flood-prone areas to safer areas and converting residential land into forest and paddy fields. It also suggests that both flood risk mitigation and provision of ESs can be further improved if local governments introduce a residence growth management strategy.

气候变化导致的极端降雨事件频率增加已引起日本的关注。2018年，国家颁布了《气候变化适应法》，制定国家和地方两级规划。政府已建议在全国范围内使用基于自然的解决方案 (NBS) 来应对日益增加的自然灾害风险。本研究采用情景分析来检验 NBS 在减轻洪水风险方面的有效性及其对提供生态系统服务 (ES) 的影响。日本滋贺县于 2015 年颁布了自己的法令。该法令考虑了现有的土地使用和建筑法规，以减轻洪水风险。定量分析假设到 2050 年有九种情景，结合滋贺当前的政策和我们对提前政策选项的最初假设来评估未来的洪水风险和 ES。分析表明，土地利用管理可以通过禁止新建住宅、将住宅用地从易受洪水影响的地区转移到更安全的地区以及将住宅用地转变为林地和水田来部分减轻洪水风险。它还表明，如果地方政府引入住宅增长管理策略，可以进一步改善洪水风险缓解和 ES 的提供。