In expanding informal neighborhoods of cities in sub-Saharan Africa, sustainable management of storm and wastewater drainage is fundamental to improving living conditions. Planners debate the optimal combination between "green" or natural infrastructure, traditional "grey" infrastructure, and "blue" infrastructure, which mimics natural solutions using artificial materials. Many advocate for small-scale, niche experiments with these approaches in informal settings, in order to learn how to navigate the intrinsic constraints of space, contested land tenure, participation, and local maintenance. This paper reports the benefits and limitations of implementing and managing local green, blue and grey infrastructure solutions in an urban informal setting. We studied ten completed public space projects that featured urban drainage infrastructure in the informal neighborhood of Kibera, Nairobi. The analysis drew from ten surveys with project designers and seven semi-structured interviews with site managers. The studied spaces featured different combinations of green, grey, and blue drainage infrastructure that have evolved over years of operation, maintenance, and change in the settlement. All projects featured participation in design, mixed design methods, hybrid infrastructure, and community governance models with potential to interact successfully with municipal actors. Results show that involvement in the co-development of small-scale green infrastructure changed people's valuation, perception, and stewardship of nature-based systems and ecosystem services. These results have implications for the larger scale adoption, integration, and management of urban drainage infrastructure. They also suggest that hybrid systems of infrastructure and governance constitute a resilient approach to incremental and inclusive upgrading.

Abstract. Reducing disaster risk is critical to securing the ambitions of the Sustainable Development Goals (SDGs), and natural hazard scientists make a key contribution to achieving this aim. Understanding Earth processes and dynamics underpins hazard analysis, which (alongside analysis of other disaster risk drivers) informs the actions required to manage and reduce disaster risk. Here we suggest how natural hazard research scientists can better contribute to the planning and development of sustainable and resilient communities through improved engagement in disaster risk reduction (DRR). Building on existing good practice, this perspective piece aims to provoke discussion in the natural hazard science community about how we can strengthen our engagement in DRR. We set out seven recommendations for enhancing the integration of natural hazard science into DRR: (i) characterise multi-hazard environments; (ii) prioritise effective, positive, long-term partnerships; (iii) understand and listen to your stakeholders; (iv) embed cultural understanding into natural hazard research; (v) ensure improved and equitable access to hazard information; (vi) champion people-centred DRR (leaving no one behind); and (vii) improve links between DRR and sustainable development. We then proceed to synthesise key actions that natural hazard scientists and research funders should consider taking to improve education, training, and research design and to strengthen institutional, financial, and policy actions. We suggest that these actions should help to strengthen the effective application of natural hazard science to reduce disaster risk. By recognising and taking steps to address the issues raised in these recommendations, we propose that the natural hazard science community can more effectively contribute to the inter-/transdisciplinary, integrated work required to improve DRR.

Participatory modelling in water resource management – involving diverse actors in what is traditionally a purely analytical process – is thought to broaden stakeholder engagement and improve outcomes. Further research and case studies are required to explore the practicalities of integrating meaningful participation within modelling processes in the water sector. Participatory modelling may be of particular interest within the context of urban informal areas, where the confluence of climate change, urbanisation and contested land requires new methods for engagement and planning. This paper develops new case-based knowledge to inform the application of participatory modelling and planning for informal urban areas. A flood-modelling project in the large informal neighbourhood of Kibera in central Nairobi, Kenya, is analysed using a newly established framework for the classification of participatory modelling approaches developed by Basco-Carrera et al. in 2017. Conclusions suggest that the further upstream more diverse stakeholders can be involved, the better the chance of co-producing new knowledge and of creating implementable plans and policies. At the same time, delivering ‘co-design’ of modelling processes in areas of limited co-operation requires a strong vision for participation, a tolerance for contention, a willingness to learn between actors and a budget to support additional time inputs.

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