開徵水權費對養殖業者之影響──以彰化縣大城鄉為例

Effects of imposing a block tariff system on aquaculture farmers--a case study of Da-Cheng Township, Chang-Hua County

臺灣西南沿海地區因養殖業者長期超額抽取地下水，導致該地區飽受地層下陷之苦，本研究以彰化縣大城鄉的蜆養殖業為例，探討政府利用區間型遞增的水權費制度來管理地下水使用時，該管制對於養殖業者的抽水行為與利潤將產生何種影響？本研究除可提供業者一個最適的決策模式外，亦可作為政府在執行水權費政策之參考。實證研究結果顯示，目前臺灣所規劃之水權費率仍太低，不足以降低大部分養殖業者使用地下水意願，僅少數養殖規模較小業者會為了面對較低費率而減少地下水的抽取，此外，政府若能調高大用水戶費率，不僅可使地下水總抽水量大幅下降，也可降低當地多數以小農生產型態為主的業者之影響，較利於水權費政策的推動。 In Taiwan, many severe land subsidence areas are mostly caused by aquaculture farmers' over-pumping groundwater. Therefore, to slow down the situation of subsidence, we should regulate the use of groundwater. Using Da-Cheng township as an example, this study tries to analyze how a proposed block tariff system on groundwater use might affect the aquaculture farmers' profits and behavior. The research not only offers the farmers an optimal decision making framework but also provides our government useful policy implications on how to adjust the block tariff system. Our empirical results show that the current proposed water tariff rates will only cause some small farmers reduce their groundwater use. In order to reduce the farmers' dependence on the groundwater, the government should consider raise the rates on higher groundwater use blocks. Doing so would significantly lower the amount of groundwater extraction. In addition, adjusting the tariff rates at higher blocks only affects a very small portion of farmers in this area. This will in turn make the regulation policy more feasible.