Bottom-Up Resilience: An Inventory of Informal Flood-Adaptation Building Practices in Ghana’s Savannah Peripheries.

Abstract

Informal settlements across Ghana's Savannah peripheries face recurrent seasonal flooding yet remain absent from mainstream engineering literature. This study documents and categorises the structural modifications and material choices, specifically raised plinths, perimeter barriers, and sandcrete construction, deployed by residents to mitigate flooding, examining how tenure security and socioeconomic factors shape adaptation intensity.
A cross-sectional survey of 384 household heads in Tamale's peri-urban peripheries was conducted using structured questionnaires. Analysis employed independent samples t-tests, chi-square tests, and ordinal logistic regression to examine structural inventories, material trust, implementation timing, and perceived efficacy across tenure groups. Secure tenure households constructed significantly higher plinths (31.2 cm vs 20.3 cm) and deployed more barrier types (mean 2.1 vs 1.7). Sandcrete was the dominant material choice (82%). Proactive builders achieved plinth heights that were 43% higher than those of their reactive counterparts. Each 10 cm increase in elevation raised safety odds by 52% (OR = 1.52), yet plinth height correlated strongly with neighbour flood impacts (rho = 0.64), exposing adaptation as a competitive rather than cooperative process. This study provides the first systematic structural audit of bottom-up flood adaptation in Ghana's Savannah peripheries, quantifying how tenure insecurity drives reversible, suboptimal construction. Findings challenge assumptions that individual adaptation improves collective resilience, with direct implications for tenure regularisation and block-level drainage policy.