翡翠水庫之水文環境特性分析

Abstract

台灣雨量豐沛，年平均降雨量為2500 mm，是世界各地年平均降雨量之2.6倍，但台灣面積小，地形狹長，山脈南北走向，河川又具有河短、坡大、水流急的特徵，時空分配不均與地形不利蓄水，導致可使用的水資源比例不到20%，再加上人口密集，每人所分配之水量僅約世界平均值的1/7，因此被聯合國列為水資源貧乏地區，為此，台灣興建了許多水庫蓄水、供水以滿足用水需求，翡翠水庫亦是為了滿足大臺北都會區用水需求而興築，因此我們想了解翡翠水庫之水文環境，簡單的探討其周邊降雨分佈，及其周邊土地利用與北勢溪水源關係。 本研究主要分析翡翠水庫周邊降雨分析，利用地理資訊系統中的漸層色做數量分類，再利用局部選取做特定距離選取來評估其周邊土地利用與北勢溪水系的關係，來觀察其建築物和果園距離水系300m、900m和1500m的多寡。分析的結果發現距離水系愈近建築物和果園的數量愈多，就可以推論出水源與人類生活息息相關。

Abstract Rainfall in Taiwan is abundant. The average annual precipitation of Taiwan can be as high as 2,500 mm. This rate is 2.6 times the annual mean precipitation of a typical region. However, Taiwan’s land area is small, and the island terrain has many sierras. Rivers are short and fast-flowing. Slopes are steep. Due to uneven distribution of populated areas, it is difficult to capture water and less than 20% of all water resources can be used. Each resident of Taiwan can only hope to access about 1/7 of the amount of water available to an average resident of Planet Earth. Therefore, Taiwan was listed as a water resources deficient area by the United Nations. For this reason, Taiwan constructed many reservoirs to supply water to residents. The Feitsui reservoir satisfies the water demand of Taipei. The present research examines the environmental hydrology of the Feitsui reservoir, and discusses its relationships to: (1) peripheral rainfall distribution, (2) peripheral land civilization, (3) Beishih stream resources. The present research uses a color-coded geography information system (GIS) analysis to classify rainfall levels in peripheral areas of the Feitsui reservoir. Furthermore, the land of Beishih steram is appraised. Buildings and orchards are mapped within distances of 300m, 900m, and 1500m from the river. These maps show that proximity to the river constitutes a noteworthy incentive to land development. This analysis gives specific details about how water resources are fundamental to land use in Taiwan.