AbstractIn this study, a cooperative game theory framework is proposed to investigate how the cooperation of groundwater consumers influences the reduction in environmental damages and benefit the stakeholders in coastal regions. To this end, an evolutionary simulation-optimization model coupled with a hydroeconomic model and different cooperation scenarios are considered. The proposed methodology is applied on a coastal groundwater system in Nassau County, Long Island, New York. The results indicate that the highest sum of net benefits achieved under the full-cooperation condition both with and without considering environmental damages. The increase in the sum of net benefits is about 7% using the full-cooperation condition compared with the noncooperation condition, whereas the groundwater withdrawal increases by about 2.5%. The risk values are higher under the full-cooperation condition compared with the baseline condition in the decrease of (1) groundwater level, (2) saltwater intrusion, and (3) filling ratio, but are lower in the submarine groundwater discharge indicator. The proposed framework can be used to assess and manage other coastal groundwater resources.