森林緩衝帶對水質改善效益之評估──以德基水庫為例

Evaluation of Benefit from Improving Water Quality by Forest Buffer Strips － A Case Study of the Te-Chi Reservoir

經前人研究顯示，森林緩衝帶能有效減少營養鹽進入水體，有效改善水庫優氧化的問題，而此一效益卻經常被人所忽略，本研究以德基水庫集水區為例，採用成本效益分析法，計算森林緩衝帶改善水質的效益，看森林緩衝帶是否值得投資。計算中的緩衝帶成本是以鄰近水體之林班造林成本計算，而效益部份則是採用替代方案的方式，以集水區之水土保持工程代替，將其成本當作緩衝帶之效益；在只考慮森林緩衝帶對於水質改善這部份的效益下，結果得到本益比為23.75，顯示森林緩衝帶的設立具有經濟效益。 According to past researches, forest buffer strip can intercept nutrient running into water solving problems of the eutrophication in water reservoirs effectively. This study uses cost-benefit analysis to elucidate the benefit of forest buffer strip improving the water quality in the Te-Chi Reservoir. Through this study, it can be determined whether it is beneficial to invest in forest buffer strip in the reservior. In this study the cost is the expenditure of reforestation near the reservoir. The benefit is determined by using the alternative to the forest buffer strip, which is the expenditure of past water and soil conservation projects. The results show that benefit-cost ratio is 23.75. Thus, to establish forest buffer strip in the reservoir is worthwhile.

According to past researches, forest buffer strip can intercept nutrient running into water solving problems of the eutrophication in water reservoirs effectively. This study uses cost-benefit analysis to elucidate the benefit of forest buffer strip improving the water quality in the Te-Chi Reservoir. Through this study, it can be determined whether it is beneficial to invest in forest buffer strip in the reservior. In this study the cost is the expenditure of reforestation near the reservoir. The benefit is determined by using the alternative to the forest buffer strip, which is the expenditure of past water and soil conservation projects. The results show that benefit-cost ratio is 23.75. Thus, to establish forest buffer strip in the reservoir is worthwhile.