Coupling stated preferences with a hydrological water resource model to inform water policies for residential areas in the Okanagan Basin, Canada

To improve the behavioural realism of a water resource model, this study coupled hydrologic modelling with stated preference research, thereby incorporating an empirical estimate of behavioural parameters to represent residents' landscape decisions in an urban environment. The stated preference data came from a discrete choice experiment in which residents were asked to choose among several possible lawn plots - varying in size, turf variety, and aesthetic qualities. The discrete choice experiment also included subsidies for lawn replacement, and information about estimated water use and watering costs for each lawn choice. We prepared a behavioural model utilizing coefficients from a mixed logit model estimated from the stated preference data, and then coupled it with a water resources model of the Okanagan Basin using the Water Evaluation and Planning System. We then conducted a scenario analysis using the coupled socio-hydrological model to simulate the extent to which residents would adopt alternative lawns under varying incentives and subsequently computed corresponding changes in water demand. The results indicate that proposing alternative lawn configurations to residents and providing site-specific information about the potential for reduced watering costs, along with a small subsidy, could lead to considerable reduction of outdoor water use through voluntary adoption. Under a scenario in which the attributes of the suggested lawn configuration matched those most preferred by residents in the choice experiment, the suggested configuration was widely adopted in the Okanagan, but a scenario with a more extreme water conserving lawn configuration reduced overall outdoor water use by a greater amount even though the configuration was adopted by a smaller percentage of residents. This study illustrates the relationship between lawn preferences and water use and supports calls to integrate hydrological and social modelling in order to capture the complex interactions between human behaviour and water use.