桃園臺地埤塘水質研究

鄧雅雲

指導教授 ： 韋煙灶

國立臺灣師範大學/文學院/地理學系在職進修碩士班/碩士(2010年)

摘要

埤塘在早期為桃園臺地最重要的農業與民生用水來源，石門水庫興建完工後，埤塘蓄水的重要性日漸降低。風災與日益極端的氣候現象讓替代水源的議題再度成為大眾關注的標的，埤塘能提供的最大水量為何？有無季節性差異？水質狀況能供做何種替代水源？本文試圖從氣候水平衡的角度去觀察其所能提供最大水量的可能性，並籍由水質分析所提供的資訊，探討水質的狀況與空間的關聯性，最後達到水資源合理利用。
　　依據桃園縣數值地圖所提供之資訊，研究區中的埤塘共有2,169口，總面積22,392,983.13m2，推估直接落在埤塘的降水量為：(總埤塘面積×逕流水深)，因此，一年裡埤塘得到的降水量有17,661,346 m3（不包含集水面積所流入的降水量），其中夏半年佔41.02%，冬半年佔58.98%，可知埤塘在冬半年雨水的蓄積上有其重要性。
研究區的埤塘水質歧異度高，最大值與最小值均有明顯的差距存在，值得注意的是，埤水的pH值偏高，DO也有同樣的情形出現，可能與日照強烈，水中藻類行光合作用有密切關聯，而代表人為污染物的無機態氮，則出現在經濟發展程度較高的都會區。
　　使用地理學的空間分析來研究各項水質參數的分布特色，得知EC、SAR、Cl-、SO42-在空間分布上，均高度極中在桃灌區第二、五支渠與石灌區中壢－過嶺支渠，這種規律性的存在，應與經濟發展有很大的關聯性。
　　透過水質的檢測，得到研究區中符合灌溉水質的埤塘，石灌區與桃灌區分別為57.14%、64.29%，但做為飲用水的符合率，石灌區與桃灌區僅有10.71%、44.44%。兩個灌區的埤圳形態截然不同，石灌區灌排的系統較易有污染物的進入，對於飲用水質符合率的改善，效果有限，相較之下，桃灌區有較獨立的灌排系統，能相對有效的控制污染物的排放，且桃灌區的埤塘面積約為石灌區的3.3倍，因此，若能有效掌握桃灌區的埤塘水質，對於整體助益較大。

關鍵字

桃園 ； 埤塘 ； 水量 ； 水質

並列摘要

In Taoyuan region, the water of ponds is the most important water source for irrigation and livelihood in early days. While the achievement of the Shihmen Reservoir, the importance of ponds’ functions is reduced gradually.
The drastic change of climate and lots of typhoons has prompted people to pay attention to the issue of water shortage. What are the maximum supplies of the ponds’ water in the period of water shortage? Is there variation about ponds’ water among seasons? The ponds’ water is whether could be turn into the substitution water or not.
This study wants to observe the possibility of the maximum ponds’ water quantity from the view point of the water balance of climate, and via to analyze the information of water quality. And then also wants to discuss the relationship between their spatiality of usage and water quality; and finally, try to get the rational water resource usages.
　　According to the provided information of Taoyuan county numerical digital maps, the number of ponds is 2,169 in study area, and the total area of ponds is 22,392,983.13m2. And we could estimate the rainfall which directly falling into ponds is 17,661,346 m3 per year (from the formula of “(total ponds’ area) times (runoff deep)”. And the source from the watersheds of ponds is excluded. The water quality collecting in summer half year is 41.02%, and in winter half year is 58.98%. Therefore, the ponds play an important role of the rainfall reservation in winter half year.
　　By way of measuring the ponds’ water quality, we can conclude: Firstly, there is 57.14% water in Shihmen irrigated region, and 64.29% in Taoyuan irrigated region in study area, which could be used for irrigation. Secondly, there is only 10.71% water in the Shihmen irrigated area, and 44.44% in the Taoyuan irrigated area, which could be used for drinking.
　　The situations of these two irrigated areas are very different. Due to the ponds which locate in the Shihmen irrigated area are more easily polluted. The outcome of water quality improving is quite limited. In contrast to Taoyuan irrigated area, because have more independent irrigation canal system; it is easier to control the discharge of contaminant. Moreover, the irrigated area size of Taoyuan is bigger to Shihmen 3.3 times. If we could better the water quality of Taoyuan irrigated area, it would be of help in a big way regarding the whole.

並列關鍵字

Taoyuan ； ponds ； water quantity ； water quality

參考文獻

江漢全（2004），水質指標，三民書局。

桃園縣政府－桃園縣埤塘數值檔資料，2009年取得。

陳其澎等（2003），桃園大圳及光復圳系統埤塘調查研究，行政院客家委員會。

楊萬全（1993），水文學增訂版，台灣師範大學地理系所。

洪佳瑩（2006），桃園地區人工埤池對水資源輔助之分析研究，中央水文科學研究所。