地景指標與溪流水中硝酸鹽濃度關係之探討－以水里溪上游集水區為例

Relationship between Landscape Metrics and Nitrate Concentrations of Streamwater in the Upper Shui-Li Creek Watershed

10.29417/JCSWC.201206_43(2).0002

葉春國(Chun-Kuo Yeh)；廖學誠(Shyue-Cherng Liaw)；詹進發(Jihn-Fa Jan)；黃正良(Jeen-Lian Hwong)；薛美莉(Mei-Li Hsueh)

地景指標 ； 硝酸鹽濃度 ； 土地利用 ； 水質 ； Landscape metrics ； nitrate concentration ； land use ； water quality

中華水土保持學報

43卷2期（2012 / 06 / 01）

109 - 122

繁體中文

健康的集水區提供多樣的生態系統財貨與服務，調節水流與淨化自然界的水為最明顯及有價值的優點，然而，土地利用的轉變卻削弱了集水區實行其生態作用的能力。在台灣本島，水質惡化已漸被認定為主要的環境議題之一，此情形與集水區土地利用有關，如何將集水區土地利用與溪流水質關連知識建立，為迫切需要的。本研究以地景指標量化水里溪上游五集水區，並將其與硝酸鹽濃度進行相關分析，結果顯示，建地邊緣長度越大，人為活動產生之廢棄物質流動容易，溪水中NO3（上標 -）濃度越高；草地面積範圍越大及連接性越佳，溪水中NO3（上標 -）濃度越低；檳榔區塊形狀越不規則，會造成越多NO3（上標 -）流失，可能與檳榔園施肥及地表逕流沖刷肥料至溪流中有關；農用地面積比例越大，溪水中NO3（上標 -）濃度越高，此亦與肥料施用有關。因此，地景指標似乎為一項有利的工具，可用來了解溪流水質的狀況。

Healthy watersheds provide a variety of ecosystem goods and services to society, and their ability to regulate discharge and purify fresh water is one of the most tangible and valuable merits. Nevertheless, changes of land use have weakened their ability to perform ecological work. It is widely recognized that degradation of water quality has become a major environmental issue in Taiwan. Deterioration of water quality is closely related to the land use in the surrounding watershed. It is urgent to understand the relationship between land use and in-stream water quality. In this study, the landscape patterns of five watersheds in the upstream watershed of Shui-Li Creek were quantified by the way of landscape metrics. In addition, correlation analysis was performed to identify the relationship between landscape metrics and nitrate concentrations. The results of data analysis indicate that nitrate concentrations increase when the patch edge of built-up becomes longer. When the patch area of grassland is bigger and its connectivity is better, the nitrate concentration is lower. Nitrate concentrations also increase when the patch shape of betel palm plantations become more irregular. This may result from fertilization and washout of surface runoff. When the percentage of farmland is high, there are higher nitrate concentrations in the stream, which may also result from the use of fertilization. Therefore, it could be suggested that landscape metrics are useful in understanding in-stream water quality.