The Code River, one of the three major rivers in Yogyakarta, plays a vital role in the city’s ecological and agricultural system. Yet, rapid urbanization and recurring floods have turned its fertile banks into sites of vulnerability. Over time, illegal squatter settlements emerged along the river, especially in Kampung Kali Code, a settlement that began on a former garbage dump. Initially composed of temporary shelters made of bamboo, cardboard, and plastic sheets, the dwellings stood just meters from the river, often swept away by seasonal floods.

The community, originally a small group of rural migrants seeking urban livelihoods, expanded into a dense and permanent settlement due to limited rural opportunities and proximity to the city center. This growth intensified environmental degradation and social tensions. Poor sanitation, lack of infrastructure, and frequent flooding created precarious living conditions, while unemployment and informal labour contributed to a reputation of disorder and marginalization.

Government-led improvement programs repeatedly failed due to insufficient community involvement and mistrust between residents and authorities. By the early 1980s, the settlement’s deteriorating conditions and negative public image led to plans for demolition, revealing deep social and environmental divides in Yogyakarta’s urban landscape.

The transformation of Kampung Kali Code was driven by a self-help program led by community leader Willi Prasetya and architect Y.B. Mangunwijaya. Eschewing permanent redevelopment to avoid legal land-use conflicts, the initiative focused on a bridge strategy to transition settlers toward a sustainable lifestyle through temporary, low-cost improvements. Supported by local newspapers and two years of voluntary tenant labor, Mangunwijaya resided within the community for six years to ensure the design authentically responded to local social dynamics and environmental vulnerabilities.

The resulting architecture drew from indigenous Javanese hamlets, utilizing bamboo, wood, and clay tiles. By employing a stilt-house typology, the scheme achieved environmental synchronization: raised structures allowed for unfettered water runoff and soil absorption while facilitating natural ventilation in the humid riverbank climate. Beyond individual shelters, the plan prioritized communal infrastructure, including shared sanitary facilities, a library, and playgrounds. Central to this social strategy was the „House of Brotherhood of Neighbors,“ a dedicated space for gathering and cooperative learning. This focus on „saved locations“ for interaction successfully increased neighborhood awareness and cohesion. Ultimately, the project’s success in upgrading a squatter settlement while maintaining a humane, traditional identity earned the Aga Khan Award for Architecture in 1992.

The Kali Code project demonstrated that architecture can resolve deep-seated social and environmental issues within marginalized settlements. Beyond disaster risk reduction, the initiative established a new social order, replacing conflict with a community life governed by shared customs. By humanizing the development process and honoring residents‘ aspirations, the project replaced the stigma of being „outcasted“ with a sense of identity, directly improving access to education and professional prospects.

The use of semi-permanent structures served as a strategic political tool. It functioned as a „soft“ intervention that delayed evictions while demonstrating a viable alternative to state-led relocation. This approach refocused governmental attention on inhabitant well-being rather than the removal of informal housing.

The project’s success eventually transformed official policy, prompting the municipality to integrate Kali Code into the Kampung Improvement Program (KIP). This led to permanent infrastructure upgrades, including flood-protection walls and improved sanitation. Furthermore, the „Kali Code experiment“ set a legal precedent, prompting the authorization of other riverbank settlements throughout Yogyakarta. Ultimately, Mangunwijaya’s work proved that social impact is achieved when architectural solutions are rooted in community dignity and political pragmatism.