Assessing the effectiveness of intervention policies for reclaimed water reuse in China considering multi-scenario simulations

Dynamic simulation for reclaimed water reuse under multi-intervention policies in China

Unconventional water constitutes the fundamental approach to addressing global water scarcity and achieving the sustainable circulation of water resources. Due to the significant environmental advantages and economical production costs, reclaimed water has emerged as a preeminent unconventional source. However, the use in China confronts the predicament of oversupply relative to demand, requiring policy measures to overcome this challenge. Limited research exists on the combined impact of subsidies and water quality information disclosure supervision on reclaimed water utilization, potentially underestimating the practical incentivizing role of water quality information disclosure. Therefore, based on the framework of 'external environment-perceived value-utilization intention,' a multi-agent-based simulation model driven by evolutionary game theory is constructed, from micro to macro perspective, to investigate the composite effects of subsidies and water quality information disclosure supervision on public intentions for reclaimed water utilization and the evolutionary track of public decision-making. The results showed that (1) The influence of subsidies on the public's inclination toward reclaimed water has regional heterogeneity. In regions with average economic development, the subsidy policy shows an inverted U-shaped correlation with the public's intention to reclaimed water, indicating the presence of an optimal value for maximizing the promotional effect of subsidies. Conversely, the effect is less discernible in regions with higher economic development. (2) In regions with average economic development, supervision of information disclosure behavior can avert the diminishing incentivizing effects under radical subsidies, but the assistance of various supervision intensities is different. (3) In regions with higher economic development, the incentive effect of subsidies can be positively modulated by the supervision policy. Interactions between subsidy and supervision policies evoke diverse chain reactions under varying intensities in these regions, and the combination of moderate subsidies and high supervision emerges as the most optimal strategy to advance reclaimed water development.

To intervene or not: the game of recycled water use for residents with different preferences

Recycled water contributes to sustainable development by providing a unified approach to wastewater treatment and rational water supply. However, the environmental benefit-sharing feature of recycled water may encourage some residents to show "free-rider" behavior. In this study, the evolutionary game model was applied to a game system consisting of two types of people, environmental preference and risk aversion. We analyzed internal and external factors and conducted a numerical simulation to seek both players' behavior evolutionary and stabilization trends. The study found that interventions are indispensable during recycled water use's initial and intermediate stages. Moreover, interventions should be tailored to different stages. In the initial stage, the benefits of co-use and the recycled water scientific information should be advertised. In the intermediate and mature stages, it is necessary to increase the trust coefficient or knowledge base of decided people who belong to early adopters of the recycled water diffusion system.