本文採用雙界二分選擇問題的假設市場評價法,同時估計淡水河系景觀與水質改善 的經濟效益,結果發現大部份的個人社經變數皆顯著地影響個人對水質或景觀改善的願付價 值(WTP),此外也發現願付金額起始點偏誤的問題,值得繼續研究。 利用WTP函數估計式,計算得水質改善的加權平均WTP值約為1,300元/人年,各級水質改 善的總經濟效益約為80億元/年;景觀改善之經濟效益約為1,500元/人年至1,900元/人年, 各級景觀改善的總經濟效益約為96億元/年至120億元/年。這些水質與景觀改善的效益值, 再加上其他效益估計值,如防洪效益,就可以與淡水河系防洪及水污染防治工程的投資成本與 維護成本相比較。

　　　　　This paper applies a double-bounded referendum contingent valuation survey in a case study that evaluates the benefits resulting from improvements in the water quality of and in the scenery surrounding the Tamshui river system in the Taipei Metropolitan Area in Taiwan. It is found that people's willingness-to-pay (WTP) for water quality and scenery improvements is highly dependent on personal characteristics such as age and income. The empirical estimation shows that the WTP is around NT$1300 per person per year for marginally improving water quality and is NT$1500-1900 for improvements in the scenery. For residents living in the Taipei Metropolitan Area, the total values are around NT$8 billion for marginally improving water quality to three different levels and are between NT$9.6 billion and NT$12 billion for improving scenery to two different levels. The environmental benefits are comparable to the total costs of those projects which are aimed at improving the water quality of the four rivers in the Tamshui river system.