On September 1^st 2009 an extreme high-impact weather event occurred in Burkina Faso that had significant impacts upon the capital city Ouagadougou and its inhabitants. Subsequent reporting and research has however not focused on the contributing socio-economic and hydrological factors and the role of global warming and climatic change remains uncertain. This reflects a paucity of evidence attributing such extreme weather events to climate change for the West Africa region and limits the knowledge base for urban planning to climate-related risks which pose serious threats. This case study provides a holistic assessment of the most extreme urban hydrometeorological event recorded in the West African Sahel, that links synoptic conditions to climate change and through to hydrological impacts on vulnerable urban populations. The intention is to inform regional decision-makers on climate change and flood-generating high-impact weather events at the urban scale and to bridge the gap between what scientists understand as useful and decision-makers view as useable at the city scale by providing interdisciplinary answers to key questions raised by local stakeholders.

Such an approach was shown to foster enhanced dialogue and engagement with stakeholders, while also providing a focus for communicating science at variable time- and spatial scales and between disciplines to improve understanding of how global processes have localised consequences. This reveals that Ouagadougou remains vulnerable to climate change and that such extreme weather events will become more frequent. But it is also demonstrated the complexity of attributing extreme events at such localised ‘urban’ scales to atmospheric phenomena affected by global climate change. Regional climate models are evolving and becoming more able to represent such extreme weather phenomena at suitable scales, enabling improved representation of climate-driven changes on such events, improving the ability for short-range forecasts in the future. Frameworks for managing flood risks however remain weak and under-resourced and there is limited capacity to manage flood risk from such events, particularly when rapid urbanisation amplifies vulnerability concerns. Recommendations are made to improve flood-resilience to future storms.

9月1^日2009 年，布基纳法索发生了极端高影响天气事件，对首都瓦加杜古及其居民产生了重大影响。然而，随后的报告和研究并未关注促成社会经济和水文因素，全球变暖和气候变化的作用仍然不确定。这反映出缺乏将此类极端天气事件归因于西非地区气候变化的证据，并将城市规划的知识库限制在构成严重威胁的气候相关风险上。本案例研究对西非萨赫勒地区记录的最极端的城市水文气象事件进行了整体评估，将天气状况与气候变化以及对脆弱城市人口的水文影响联系起来。

这种方法被证明可以促进与利益相关者的对话和参与，同时也为在不同的时间和空间尺度以及学科之间传播科学提供了重点，以提高对全球过程如何产生局部后果的理解。这表明瓦加杜古仍然容易受到气候变化的影响，并且此类极端天气事件将变得更加频繁。但也证明了将这种局部“城市”尺度的极端事件归因于受全球气候变化影响的大气现象的复杂性。区域气候模型正在不断发展，并且越来越能够在适当的尺度上代表此类极端天气现象，从而能够更好地代表此类事件的气候驱动变化，从而提高未来短期预报的能力。然而，管理洪水风险的框架仍然薄弱且资源不足，并且管理此类事件造成的洪水风险的能力有限，特别是当快速的城市化加剧了脆弱性问题时。提出了提高对未来风暴的抗洪能力的建议。