Testing Flood-Resilience Measures with Indices: Case Studies in Lower Kelani Basin, Sri Lanka, and Applicability to the Developing World

Abstract

Floods pose growing risks to vulnerable areas due to climate variability and change and rapid urbanization, making resilience an essential approach for living with recurrent flood events. Developing a flood-resilience index is challenging due to the numerous uncertainties involved, but it is vital for assessing a region’s capacity to withstand floods. This study constructed a flood-resilience index using 29 indicators across 5 dimensions: natural, physical, social, economic, and institutional. Data were collected through household surveys, interviews, and hydraulic modeling in three flood-prone Grama Niladari (GN) divisions in Sri Lanka: Megoda Kolonnawa, Pahala Bomiriya, and Kerawalapitiya. The results show that applying locally tailored resilience interventions, such as flood insurance, elevated housing, and sponge city strategies, substantially improved resilience scores: from 0.495 to 0.557 in Mgoda Kolonnawa, from 0.489 to 0.573 in Pahala Bomiriya, and from 0.485 to 0.569 in Kerawalapitiya. The proposed framework supports the selection of effective interventions for building flood-resilient communities, and was validated in the lower Kelani River Basin of Sri Lanka. These interventions are broadly relevant to developing countries, in which communities already are adopting similar measures to enhance their resilience to floods. Overall, the improved index scores confirm the framework’s value in evaluating resilience-building options prior to implementation.