以標準化地下水與降雨指數法評估高屏溪流域之乾旱特性

SGI and SPI for Drought Characteristics in Gaoping River Basin, Taiwan

葉信富(Hsin-Fu Yeh) ； 張家富(Chia-Fu Chang) ； 李哲瑋(Jhe-Wei Lee) ； 李振誥(Cheng-Haw Lee)

《中華水土保持學報》 47卷1期 (2016/03) Pp. 45-52

https://doi.org/10.29417/JCSWC.201603_47(1).0005

摘要

近年來受到極端氣候的影響，臺灣面臨嚴重的缺水危機，且因降雨型態的改變，使得乾旱現象愈趨明顯，間接影響地下水的補注。因此，本研究以高屏溪流域作為研究區域，選定6 個地下水位站及鄰近6 個雨量站之長時間監測資料，利用標準化地下水指數評估法 (Standardised Groundwater Index, SGI) 與標準化雨量指數評估法 (Standardised Precipitation Index, SPI) 分析該區域乾旱特性。本研究分析高屏溪流域1997 年至2014 年地下水位與雨量資料，結果顯示，2003 年至2005 年為高屏溪流域之連續乾旱年，且由2014 年的趨勢判斷高屏溪流域乾旱之嚴重程度有逐漸上升的趨勢。另外，透過計算SGI 和SPI 兩者間的交互相關函數分析其最大交互相關函數 (q_(max))，結果顯示q_(max) 與乾旱事件持續的時間為正相關，並得知q_(max) 越大發生乾旱事件持續的時間越長，反之當q_(max) 越小則持續時間越短。且由研究結果發現q_(max) 具有地理位置上的差異性，位於旗山溪與荖濃溪所處各測站之q_(max) 較小，而位於隘寮溪以下測站之q_(max) 呈現較大之情形，所以未來若隘寮溪以下之區域發生乾旱事件，本研究推估其乾旱的持續時間也會相對較長。本研究結果亦可提供未來高屏溪流域水資源管理參考。

關鍵字

標準化地下水指數 ； 標準化雨量指數 ； 交互相關函數 ； 乾旱

並列摘要

Taiwan has been facing severe water crises in recent years owing to the effects of extreme weather conditions. Changes in precipitation patterns have also made the drought phenomenon increasingly prominent, indirectly affecting groundwater recharge. Hence, in the present study, long-term monitoring data were collected from the study area of the Kaoping River Basin. Specifically, data from six selected groundwater level stations and six precipitation stations in the vicinity were collected between 1997 and 2014. The standardized groundwater index (SGI) and standardized precipitation index (SPI) were then used to analyze the region’s drought characteristics. The results revealed continuous droughts occurred in the river basin from 2003 to 2005. The trend for 2014 further indicated the drought situation in the region would worsen in terms of severity. After calculation and analysis of the cross correlation function between the SGI and the SPI, a positive correlation was identified between the maximum cross correlation function (q_(max)) and the duration of the drought event. The larger the q_(max) value, the longer the duration of the drought, and vice versa. The study also found the q_(max) value varied with geographical locations: it was smaller for the various measuring stations located along the Qishan and Laonong rivers, but tended to be larger for stations located beyond the Ailiao River. Thus, this study reckoned if a drought event were to occur in the latter area in the future, its duration would be relatively longer. The findings of this study could also serve as future reference for the water resources management of the Kaoping River Basin.

並列關鍵字

Standardized groundwater index ； Standardized precipitation index ； Cross correlations ； Drought