Evaluation of hub layout schemes for multi-branched rivers in Ganjiang River estuary based on TOPSIS method

Targeting the hub project of multi-branched rivers in Ganjiang River estuary, this study conducts researches on technical schemes including dam site selection, ship lock and sluice layout. An evaluation index system containing 14 indicators is established from three dimensions namely economic benefit, ecological protection benefit and social benefit. Representative stakeholders including government construction departments, ecological and environmental protection departments, local communities and construction enterprises are selected. The analytic hierarchy process (AHP) is adopted to determine subjective weights, and the Shapley value method is used to introduce game theory mechanism for combined weighting. Meanwhile, the entropy weight method is applied to calculate objective weights, and the effects of various subjective and objective weighting methods are compared. Finally, the TOPSIS method is used to optimize all alternative schemes. The research results show that stakeholders have obvious differences in indicator preference. Governments and enterprises pay more attention to economic benefits, environmental protection departments focus on ecological protection benefits, while communities prioritize social benefits. Game based weighting can effectively balance the demands of all parties. Combined with objective weights, the overall weight distribution becomes more balanced, which improves the fairness and objectivity of evaluation results. The comparison results indicate that the discrepancy among schemes mainly depends on the coverage scope of layout units and the convergence degree of external constraints. Layout schemes such as sluice on the south branch, ship lock on the middle branch and dam site on the north branch have close comprehensive scores due to fewer involved indicators and similar indicator values, while distinct differences exist among other schemes.