Universität zu Köln

Lange, Wolfram Johannes ORCID: 0009-0001-8571-4111 (2026). Ecosystems, Communities, and Resilience: Nature-Based Solutions for Climate Change Adaptation and Disaster Risk Reduction in Brazil. PhD thesis, Universität zu Köln.

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Abstract

In recent decades, Brazil’s relationship with hazards and disasters has become increasingly fraught. For instance, the devastating 2011 Rio de Janeiro floods and mudslides, which killed over 900 people, changed how researchers and policy makers considered disaster risk. Consequently, this thesis analyzes environmental issues not through the traditional more engineering lens but by investigating whether nature itself might offer better solutions. Therefore, this research analyzes Nature-Based Solutions (NBS), which are actions to protect, restore, and sustainably manage ecosystems to address societal challenges such as climate change and disaster risk while providing certain co-benefits. This thesis examines this idea through three interconnected studies across different Brazilian contexts, from Rio de Janeiro’s mountainous regions to Salvador da Bahia’s informal settlements. Brazil's vulnerability to disasters extends beyond the impacts of extreme weather events, although the exacerbating role of climate change cannot be overlooked. A significant contributing factor to this problem is the longstanding deforestation and environmental degradation, particularly within the Atlantic Forest (Mata Atlântica), coupled with less controlled urban development. These combined factors have undermined the natural systems that once provided protection to the region. The loss of forest cover, for example on steep slopes, and its replacement with informal settlements, significantly increases the likelihood of disasters. The first major component of this thesis explores policy analysis in Rio de Janeiro State. Generally, Brazil has passed progressive environmental legislation, including the National Forest Code, which mandates Permanent Preservation Areas (APPs) along waterways and on steep slopes, among other landscape features. On paper, these laws should significantly protect against landslides and floods. In practice, however, enforcement has been uneven, particularly in areas where vulnerable populations have few housing alternatives. This policy analysis reveals that the country is not lacking less in intentions or laws to protect the environment and adapt to climate change. For instance, the country has established the National Climate Change Policy, various disaster risk reduction frameworks, and support ecosystem-based approaches. However, such guidelines are not always implemented, displaying what researchers call the “policy practice gap.” Frequently, local authorities favor more technical or engineering solutions, such as concrete barriers and drainage systems over, e.g., forest restoration that might be less effective in the long run. The second study involves community perceptions, specifically in Teresópolis in Rio de Janeiro’s mountainous region. This research reveals a complex dynamic: while it may be assumed that populations residing in disaster-prone regions would readily adopt NBS to mitigate the risks of landslides and floods, the reality is more nuanced. Although local residents are aware of their vulnerability to such hazards, there appears to be a limited understanding of the relationship between ecosystem health and personal or community safety. This finding suggests that measures to reduce disaster risk with NBS can succeed only if communities understand and support these measures revealing an “ecological literacy gap”. For instance, people might see forests as potential fire hazards or sources of pests rather than protective barriers. This perception highlights the need for more sophisticated public education about ecosystem services. The third study examines the technical effectiveness of NBS in Salvador da Bahia’s informal settlements, comparing them directly with conventional engineering approaches. Through interviews and participatory workshops the authors found that experts frequently viewed NBS to be as effective as and more cost efficient than traditional technical or engineering measures for landslide prevention. The potential cost-effectiveness of NBS warrants careful consideration. While engineered solutions such as retaining walls typically require substantial upfront investment and ongoing maintenance, research suggests that vegetation-based slope stabilization may provide comparable protection at potentially lower cost while delivering additional co-benefits including improved air quality, carbon sequestration, and enhanced biodiversity. However, the economic assessment of NBS remains complex, as comprehensive cost-benefit analyses must account for temporal variations in ecosystem performance, uncertainty in long-term effectiveness, and the challenge of monetizing multifunctional benefits that accrue to different stakeholder groups over varying time horizons. Additionally, this thesis investigates broader questions about governance and financing. Implementing Nature-Based Solutions at scale requires coordination across multiple agencies and sectors—environmental, urban planning, disaster management, and social services. Brazil’s institutional landscape appears fragmented, with different agencies operating in silos. Financing presents another challenge for increased implementation of NBS. Although NBS might be cost effective in the long run, they require different funding models than traditional infrastructure. The benefits of such solutions are diffuse and long term, making them difficult to quantify for budget-conscious officials seeking immediate results. Overall, this research reveals a situation with significant potential constrained by institutional, social, and technical barriers. NBS are not panaceas, but they appear to offer genuine advantages over purely engineered approaches, particularly when implemented thoughtfully with community input. Ultimately, successful disaster risk reduction requires frequently hybrid approaches combining natural and engineered systems while addressing the social and governance factors that determine whether an intervention succeeds.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Lange, Wolfram Johannes w.lange@gmx.net https://orcid.org/0009-0001-8571-4111 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-801501
Date:	2026
Publisher:	UBS
Place of Publication:	Cologne, Germany
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Geographisches Institut
Subjects:	Earth sciences Life sciences
Uncontrolled Keywords:	Keywords Language Climate Change Adaptation English Disaster Risk Reduction English Nature-based Solutions English
Date of oral exam:	18 December 2025
Referee:	Name Academic Title Kraas, Frauke Prof. Dr. Hamhaber, Johannes Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80150