Abstract

In this paper, we discuss an upstream-downstream externality related to water quality (the level of ammonia) in a river by distinguishing between a non-cooperative and cooperative case. As empirical case, we use the Porong River, which is located in the East Java province of Indonesia. In this river, aquaculture farmers are located downstream while the industrial firms are placed upstream. In both the non-cooperative and cooperative case, we find that the optimal profit by a polyculture is higher than the optimal profit for an industrial firm, and this result is robust to variations in relevant parameter values. Furthermore, by comparing the non-cooperative and cooperative cases, we find that the optimal gain of moving to joint management is reasonably high, and when varying relevant parameter values, this gain remains almost unchanged.

摘要

在本文中，我们通过区分非合作和合作案例来讨论与河流水质（氨水平）相关的上下游外部性。作为实证案例，我们使用位于印度尼西亚东爪哇省的波龙河。在这条河中，水产养殖户位于下游，而工业企业则位于上游。在非合作和合作情况下，我们发现混养的最优利润高于工业企业的最优利润，并且这个结果对于相关参数值的变化是稳健的。此外，通过比较非合作和合作案例，我们发现转向联合管理的最优增益相当高，并且当改变相关参数值时，该增益几乎保持不变。