台灣南部降雨量與降雨沖蝕指數之時空變化

Temporal and Spatial Variations of Rainfall and Rainfall Erosivity in Southern Taiwan

李明熹(Ming-Hsi Lee) ； 廖怡雯(Yi-Wen Liao) ； 徐千筑(Chien-Chu Hsu)

《農業工程學報》 64卷1期 (2018/03) Pp. 41-59

https://doi.org/10.29974/JTAE.201803_64(1).0004

摘要

近年來極端降雨事件發生頻繁，台灣南部之降雨特性有降雨集中與降雨強度增加的趨勢，一旦降雨特性改變，降雨沖蝕指數(R)即隨之變化，進而影響土壤沖蝕量，因此，重新修訂降雨沖蝕指數以符合現今氣候狀況乃刻不容緩。本研究為瞭解降雨特性的改變對降雨沖蝕指數之影響，根據台灣南部區域(台南市、高雄市及屏東縣)95個中央氣象局雨量站14年(2002~2015)10分鐘雨量資料及1993年至2001年之60分鐘等間隔降雨資料，分析各雨量站的有效降雨事件之降雨特性變化，建立降雨量與降雨沖蝕指數之關係式，並探討其時間及空間變化。有效降雨事件之降雨特性分析結果顯示，單場最大降雨量發生於2009年莫拉克颱風期間，約佔全部雨量站之66% (63個雨量站)；最大年降雨沖蝕指數範圍約介於24,822~168,715 MJ-mm/ha-hr-yr之間，最大值與最小值分別為台南七股寮及高雄旗津雨量站。時間變化分析結果顯示，月平均降雨量(Pm)及月平均降雨沖蝕指數(Rm)於9及11月份有逐年上升之趨勢；季平均降雨量(Ps)及季平均降雨沖蝕指數(Rs)於夏、秋及冬季有逐年上升之趨勢；年平均降雨量(Py)及年平均降雨沖蝕指數(Ry)均為逐年上升之趨勢。空間變化分析結果顯示，月、季及年降雨沖蝕指數大致上由西或西南部向東或東北部遞增，且最大Ry有逐年增加之趨勢，其最大值發生位置有往北移動之趨勢。

關鍵字

降雨沖蝕指數 ； 時間變化 ； 空間變化

並列摘要

In recently years, trend of the rainfall characteristics have gradually changed due to extremely heavy rainfall event in the world. Rainfall is the major cause of soil erosion dynamic factor. The purpose of the present study is estimating the rainfall erosivity based on event, monthly, seasonal and annual precipitation data, respectively. Temporal and spatial variations of rainfall and rainfall erosivity are investigated using a dataset monitored by 95 rainfall stations in southern Taiwan. The results show that there are 70% of all rainfall erosivity stations that the individual maximum rainfall amount occurred during typhoon Morakot, 2009. The maximum annual rainfall erosivity varied from 24,822 to 168,715 MJ-mm/ha-hr-yr. Temporal variation of rainfall and rainfall erosivity shows that the average monthly rainfall and rainfall erosivity increase yearly in September and November. The average seasonal rainfall and rainfall erosivity increase yearly in summer, autumn, and winter. The average annual rainfall and rainfall erosivity increase yearly. The spatial analysis shows average monthly, seasonal and annual rainfall erosivity increase from west to east or southwest to northeast. The results of this study can serve as a helpful reference for relevant institutes and departments.

並列關鍵字

Rainfall erosivity ； Temporal variation ； Spatial variation