Nature-Based Infrastructure for Artisanal and Small-Scale Mining Closure in Marmato, Colombia

Marmato, in Colombia’s Caldas region, has a centuries-old tradition of artisanal and small-scale gold mining. While the sector has provided livelihoods for thousands of people, poorly planned or unmanaged mine closures often leave behind degraded landscapes, contaminated waterways, and heightened risks of floods, erosion, and landslides. These legacies undermine community well-being and resilience, while offering few sustainable alternatives once mining ends. Today, around 9,000 residents and up to 357 small-scale mining operations are directly affected by these challenges. 

The NBI Centre is assessing how nature-based infrastructure (NBI) can turn mine closure into an opportunity for regeneration. The study will compare three scenarios: 

• No action, where ASM sites are abandoned without closure. 

• Traditional closure, involving soil compaction, limited water treatment, and fencing. 

• NBI-focused closure, with measures such as reforestation using native species, restoration of natural hydrological systems, soil remediation, and support for alternative livelihoods. 

By comparing these scenarios, the assessment explores how NBI could help reduce climate and environmental risks, stabilize soils, improve water regulation, and support biodiversity. It also considers how NBI might reduce the need for expensive grey infrastructure by using wetlands, bioswales, and riparian buffers to filter contaminants and protect communities from flooding and erosion. It will also bring light on how NBI-based closure can align with Colombia’s National Development Plan, Nationally Determined Contributions, and mining legislation, offering lessons for other ASM regions across Latin America and beyond.