Human–water interactions and drought adaptation: insights from global cases and socio-hydrological modelling

Drought risk emerges from multi-directional feedbacks between water availability, risk perception, and adaptation decisions. Human activities both aggravate and alleviate hydrological drought. Adaptation measures to cope with drought can generate negative unintended consequences for other water users, but also unintended benefits.

A global synthesis of 28 cases reveals that water abstraction consistently intensifies drought severity, while reservoir releases can reduce deficits during dry periods but often alter seasonality, leading to wet-season shortages. Drought adaptation measures rarely offset the impacts of water abstraction, but instead shift drought effects in space or time. For example, water transfers reduce deficits in the receiving basin, but increase them in the providing basin, and groundwater-derived streamflow augmentation alleviates extreme low flows, but at the expense of reduced flows during other flow periods.

To further explore the effects of drought adaptation, we developed integrated socio-hydrological tools using system dynamics (SD) and agent-based models (ABM). SD analyses revealed that societies with homogeneous risk-attitudes implement fewer collective measures, opting for more individual measures to address drought risk. However, individual measures by specific social groups may lead to unsustainable water use and therefore larger drought damages. SD analysis in Crete shows that single-sector climate service prioritization amplifies sectoral benefits but increases systemic vulnerabilities, whereas equitable cross-sectoral prioritization fosters balanced, sustainable outcomes.

ABM applications highlight spatial trade-offs, with individual measures also affecting downstream or neighbouring water users. For example, in the Netherlands, irrigation pumping reduces neighbours’ water availability, while measures to raise groundwater levels benefit surrounding farms. In Kenya, upstream commercial abstractions amplify downstream drought risk, and water harvesting improves short-term access but reduces discharge downstream.

These findings underscore the complexity of drought management and the need to represent social diversity, institutions, and cross-scale hydrological feedbacks to design equitable and sustainable adaptation pathways.