投資組合理論之水資源系統管理

Abstract

台灣位於熱帶及亞熱帶的交界，年平均降水量約為2500毫米，為世界平均的2.6倍，但由於地形陡峭和土地狹小，降水難以儲存，僅有18%的降水量可利用。台灣的降水在時間和空間上分布不均，豐水期集中在每年5至10月，枯水期則在11月至次年4月。北、中、南部地區的降水量分布亦存在顯著差異，導致中、南部地區在枯水期經常面臨用水不足的問題。 現有的水資源管理面臨諸多挑戰，如水庫蓄水能力不足、管道漏水率高、農業灌溉效率低等，難以應對季節性和地區性的用水需求波動。現代投資組合理論（MPT）在資源分配和風險管理中展示了潛力，能夠通過平均數－變異數的概念分析平衡風險和回報，成為優化水資源分配的理想工具。 本研究旨在應用MPT優化台灣的水資源管理策略，以應對降水分布不均的挑戰，提高水資源利用效率。研究目標包括建立水資源分配模型、分析現有管理策略效能、優化分配策略，特別針對中、南部枯水期用水需求，並提供具體的政策建議。期望通過這些目標的實現，為台灣提供科學、有效的水資源管理解決方案，促進可持續發展。

Taiwan is located at the intersection of tropical and subtropical regions, with an average annual rainfall of about 2,500 millimeters, which is 2.6 times the world average. However, due to steep terrain and limited land area, it is difficult to store rainfall, and only 18% of it is utilizable. The distribution of rainfall in Taiwan is uneven in terms of both time and space, with the wet season concentrated from May to October and the dry season from November to April. There are also significant differences in rainfall distribution across northern, central, and southern regions, leading to frequent water shortages in central and southern regions during the dry season. Current water resource management faces numerous challenges, such as insufficient reservoir storage capacity, high pipeline leakage rates, and low agricultural irrigation efficiency, making it difficult to cope with seasonal and regional fluctuations in water demand. Modern Portfolio Theory (MPT) has shown potential in resource allocation and risk management. By applying the mean-variance concept, it can balance risk and return, making it an ideal tool for optimizing water resource allocation. This study aims to apply MPT to optimize Taiwan's water resource management strategy, addressing the challenges of uneven rainfall distribution and improving water resource utilization efficiency. The research objectives include establishing a water resource allocation model, analyzing the effectiveness of current management strategies, optimizing allocation strategies, particularly targeting water demand during the dry season in central and southern regions, and providing specific policy recommendations. By achieving these objectives, this study hopes to provide a scientific and effective solution for water resource management in Taiwan, promoting sustainable development.