Adapting Archipelagic Heritage to Climate Change: Evidence from Historic Shimoni Town and Wasini Island, Southern Kenya Coast

Abstract

Sea-level rise, erosion, and accelerated beach loss are increasingly threatening Kenya's insular and archipelagic heritage landscapes. Across Shimoni’s archipelago, consequences ranging from gradual decay, collapse to outright catastrophic loss of sea front mosques, tombs, wells, shrines, coral stone and wattle-daub buildings are indicative of absent heritage management and climate adaptation plans. To support climate sensitive conservation in historic Shimoni Town and Wasini Island, Island Vulnerability and Archipelagic Planning Systems Theory was examined to quantify landscape metrics, entropy and spatial change based on Landsat images from 1984-2023. Geo-spatial indicators selected to quantify ecological change include Patch Density, Mean Patch Size, Largest Patch Index and Landscape Shape Index. These landscape metrics were selected to determine patch isolation, evenness, dominance and complexity, respectively. In 40 years, built-up and barren land areas increased by 73% and 32% respectively while mangrove cover and terrestrial vegetation decreased by 69% and 33% respectively. Coral outcrops and sandy beach decreased by 14% and 69%, respectively. Urban expansion quadrupled at a rate of 1.26km2/year indicated by Shannon’s entropy values that increased from 0.003 to 0.024. Bare land and built-up patch densities increased by 38% and 60% respectively. Mean patch sizes for mangrove and terrestrial vegetation decreased by 100m2 and 200m2 respectively. Overall. Landscape metrics highlighted increasing urban sprawl into heritage sensitive zones. Conservation and historic town planning is to consider stabilization, consolidation and adaptive reuse for flood vulnerable built heritage. Archipelagic planning is to consider the critical adjustment of shoreline setbacks, forest buffer zones, flood risk zones, mangrove restoration, afforestation, vertical densification, planned retreat and land use control to protect low lying historic sites from ongoing and future climate change.