A new Socio-Hydro-Epidemiological model for simulating adaptation dynamics between drought and dengue

Dengue incidence and drought severity are rapidly rising globally. It has been shown that measures adopted to cope with drought may unintentionally increase mosquito breeding habitats. Empirical work has linked domestic rainwater harvesting tanks to increased Aedes aegypti presence in urban settings. Yet, conventional epidemiological models rarely represent household behaviour and water-use decisions, while socio-hydrological models typically do not account for how hydro-climatic extremes shape the vector-borne diseases.Here we present a system dynamics model that, for the first time, explicitly couples climate variability, water shortages, dengue, adaptation options, and social behaviour. We integrate a dengue epidemiological framework with a socio-hydrological representation of human–water interactions, and we examine three adaptive pathways: (i) a dengue-focused response emphasising mosquito control; (ii) a drought-focused response prioritising rainwater tanks for household supply and considering migration as an adaptation to drought; and (iii) a co-adaptation strategy that combines drought and dengue measures, guided by evolving social awareness.Our results indicate that adaptation choices strongly shape awareness dynamics, water scarcity, the number of infected mosquitoes, and ultimately dengue incidence. Drought-focused strategies reduce average water shortages, but lead to prolonged standing water in rainwater tanks that amplify mosquito proliferation and increase infections. Co-adaptation, through responsive diversification of measures and timely management of tank storage, can preserve drought buffering benefits while limiting suitable habitat for vectors. The proposed model can be used to (i) better predict dengue outbreaks to prioritise surveillance and resource allocation, and (ii) test the effectiveness of combined adaptation portfolios under climate-change scenarios.