Abstract: The basin resources are shared by all places along the line for their special status as public goods. For transboundary rivers, they are shared and managed by all participants in the basin. However, there are differences in geographical location, economic development and dependence on water resources among participants. Therefore, different participants have different degrees of attention to river pollution control and expected investment, which are contradictory. The disunity of upstream and downstream countries’ pollution control intention is the key factor hindering the pollution control of transboundary rivers. The pollution control of transboundary rivers has the following two characteristics: On the one hand, the fluidity and spatial timing of rivers lead to the negative externality of the pollution control of transboundary rivers, that is, the pollution behavior of one country or region will have adverse effects on the downstream countries. In contrast, downstream participants are at a disadvantage, so this conflict of interests often leads to tension and conflict between upstream and downstream participants. On the other hand, the non-competitive nature of pollution treatment of transboundary rivers means that less treatment of river pollution by countries along the basin may directly affect their own water usage. Upstream participants are not significantly negatively affected by the quality of water usage in their country by non-participation or low participation in pollution control. Cross-border rivers are shared by all parties, and the quality of their water is of vital interest to all. Therefore, whether good international cooperation can be reached in the process of river pollution control and cross-border river joint management is the key to improving the water quality of the basin.
Considering the spatial differences among participants of transboundary rivers, this paper uses the first-order expression equation of the evolution of concentration value of organic COD natural digestion in the basin to describe the relationship between river pollution control and river spatial timing. Four cost allocation methods are selected according to the development law of alliance formation for comparison, that is, initial alliance formation, dynamic trial-and-error adjustment, bringing in more partners and maintaining stability. The minimum core method that emphasizes minimum cooperation cost, SCRB method that focuses on dynamic process of decreasing cost, Shapley value method that emphasizes fairness, and Owen value method that focuses on stability are compared, aim to comprehensively consider multiple factors such as fairness, attractiveness, stability, strategic adaptability and sustainability. To develop more effective strategies for pollution control of transnational rivers, this comparative analysis helps decision-makers better understand the advantages and disadvantages of various approaches to better meet the needs and interests of all parties to improve water quality and environmental sustainability. Finally, a case study of Lancang-Mekong River is carried out to explore a win-win cooperation system for trans-boundary river pollution control from the perspective of cost allocation.
For watershed pollution control, the total cost of cooperation is significantly lower than that of non-cooperation. The cost sharing among the participants is basically based on the difference in the individual cost of pollution control among the participants, and the results of the middle tier countries (Thailand and Cambodia) are relatively different with several methods of sharing. Last-resort countries share the least in a cost-sharing approach that takes into account marginal contributions. When conducting joint pollution control in the Lancang-Mekong River basin, full consideration should be given to the difference in marginal cost of cooperation among participants and the amount of pollution emitted by participants in the pollution process, which is the focus of basin cooperation in pollution control and runs through the whole process of cost sharing in the cooperative alliance. Fairness, stability and satisfaction of cost sharing are the key to international basin pollution control.

Key words: cross border river management, cost sharing, cooperative game, Owen-value method

摘要： 流域的跨境性是跨界河流污染治理困难的关键原因。考虑到跨境河流具有负外部性和消费的非竞争性,本文使用污染物浓度扩散的一级演进方程建立了体现沿河各参与方空间差异的治污成本特征函数,对跨境河流联合治污时的成本分担状况予以剖析。最终选取澜沧江-湄公河流域当作实例展开研究。经研究可知,合作治污能够使流域整体成本切实降低,各参与方所分担的成本会因各自单独治污成本的不同而产生变动;跨境流域开展合作治污时,关键在于全面考量各参与方合作治污的边际成本差异以及污染排放量,其中成本分担的公平性、稳定性与满意度对国际流域污染治理起着极为关键的作用。

关键词: 跨境河流治理, 成本分摊, 合作博弈, Owen值法