探討土地利用對溪流水水化學之影響──以新化林場為例

The influence of the land use on stream water chemistry-an example of the Hsinhua Forest Station

"本研究監測國立中興大學新化林場之溪流水水化學與流量，藉由主成分分析（principal component analysis, PCA）探討影響流經林場的虎源溪水化學之因素，並由虎源溪之離子通量，釐清溪流周圍土地利用對離子輸出的影響。乾季時的主成分分析結果顯示，第一主成分占總變異量之39.41%，以電導度、Ca^(2+)和Mg^(2+)有較高負荷量，因人為活動產生的鈣與鎂化合物會輸入至溪流中；第二主成分之變異量為17.47%，以總懸浮固體、HCO_3^-及K^+為主，推測是與溪流水流路徑相關。濕季第一主成分亦是受到人為開發的影響，其變異量為38.3%，以電導度、Mg^(2+)、Ca^(2+)與Cl^-具較高負荷量；第二主成分之變異量為18.17%，以溶氧、HCO_3^-和總有機碳（total organic carbon, TOC）的負荷量為高，推論與生物活動有關。樣點集群分析中發現總有機碳與離子通量在溪流前段（上游段）、森林步道區及遊憩區較低，而在虎源溪中後段（中下游段）呈現最大的通量。虎源溪周圍農業活動會增加溪流中養分通量，同時河道工程也會提高輸入溪流中的總有機碳與離子，導致溪流後段通量增加。總結虎源溪離子濃度乾季主要會受到人為開發、溪流水路徑及工程擾動的影響，濕季主要是受人為開發與生物活動影響。虎源溪離子通量主要受到人為干擾的影響，並顯示森林步道區與遊憩區之溪流具有較低離子通量，可驗證森林涵養水資源和淨化水質功能；亦希望本研究的結果可作為虎頭埤水庫集水區經營管理之參考。"

"This study analyzed stream water chemistry by principle component analysis (PCA) and monitored discharge of streamflow for exploring factors that impacting stream water qualities. The results of PCA of the dry season showed that PC1 explained 39.41% of the variance due to higher loading of Ca^(2+) and Mg^(2+) conductivity because of the calcium and magnesium compounds imported into stream water by human activities. The PC2 explained 17.47% of the variance which mainly composed of total suspended solids, HCO_3^- and K^+, and the higher concentration of those ions are presumably related to the runoff. In the wet season, PC1 is affected by artificial development that explained 38.3% of the variance. PC2, which explained 18.17% of the variance, is composed by dissolved oxygen, HCO_3^- and total organic carbon (TOC), which is believed to related to biological activities. Cluster analysis showed low TOC and ions flux in upper section of the Huyuan stream, but these flux showed highest quantities in the stream section close to forest trails and recreation area. The emissions of agricultural activities lead to the increase of TOC and ions flux. The engineering works at the river also increase the fluxes of TOC and ions. The concentration of ions was affected by the development, runoff path and engineering in the dry season, and affect by development and biological activities in the wet season. The lower flux in the stream closing forest and recreation areas suggested that ions flux is mainly affected by human, prove that forest had the function of conserving and improve water quality. The results of this study can be used as a reference for the operation and management of the Hutoupi Reservoir watershed area."