利用羅吉斯迴歸法分析崩塌對土石流降雨警戒基準值之影響-以南投神木村為例

Applying Logistic Regression Method to Analyze the Effect of Landslide on Rainfall Threshold Value for Debris Flow Warning –Using the Site of Shenmu, Nantou as An Example

張綸纖(Lun-Hsien Chang)

指導教授 ： 范正成

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.00802

摘要

本研究主要為探討崩塌及其他地文因子，對土石流降雨警戒基準值（rainfall threshold value for debris flow warning）之影響，並進而推估之。土石流降雨警戒基準值為現今臺灣地區發布土石流警戒參考之依據，以供為預警指標，並於每年或遇重大土砂災害事件後檢討修訂。
本研究之研究區域位於南投縣信義鄉神木村，蒐集研究區域內土石流發生之事件，利用羅吉斯迴歸法分析。並統計前人研究中最常被使用作為探討土石流事件發生與否之地文因子，利用溪床平均坡度、崩塌地面積及有效集水區面積等地文因子推估土石流降雨警戒基準值。根據分析結果得知，資料比例以發生土石流：未發生土石流為1：1時，有較高之敏感度，高達87%。顯示當土石流發生事件與不發生之土石流事件資料比例較相近時，有較佳之預測結果。
另外本研究中利用羅吉斯迴歸法分析推估得到土石流降雨基準之公式。推估公式所用之參數為溪床平均坡度、崩塌地面積、有效集水區面積及有效累積雨量。並以賀伯颱風之事件作驗證，研究顯示當地文條件類似賀伯颱風時，有效累積雨量只要達到713.5mm即有可能會發生土石流。

關鍵字

土石流警戒基準 ； 羅吉斯迴歸 ； 崩塌 ； 土石流

並列摘要

The main purpose of this study is to investigate the effects of landslides and other physiographic factors on the rainfall threshold value for debris flow warning and then to evaluate it. In Taiwan, the rainfall threshold value for debris flow warning has been used for years as a basis to announce debris flow warning and it is amended annually or after the event of great mass movement disasters.
The site of this study was selected at Shen-mu, Nan-tou. The debris flow events occurred in the site were collected and the method of logistic regression was used for analysis. Statistical analysis was made on the physiographic factors which were mostly commonly used in the previous studies to investigate the occurrence of debris flow. In this study, average riverbed slope steepness, landslide area and effective watershed area were used to estimate the rainfall threshold value for debris flow warning. From the results, it was found that when the ratio of the data in proportion to the occurrence of debris flow and non occurrence of debris flow was 1 to 1,the sensitivity was higher and up to 87%. This indicated that when the debris flow events of occurrence and non occurrence were similar, there would be a better prediction.
In addition, the equation for evaluating rainfall threshold value for debris flow using the logistic regression analysis was obtained. The parameters used for evaluation were average riverbed slope steepness, landslide area, effective watershed area and effective cumulative rainfall. The event occurred during Herb typhoon was used as an example for validation. If the physiographic factors are similar to that during Herb typhoon, debris flow may occur while the effective cumulative rainfall reach 713.5mm .

並列關鍵字

rainfall threshold value for debris flow warning ； logistic regression ； landslide ； debris flow

參考文獻

29.劉哲欣（2009），「利用降雨及地下水水質資料進行土石流發生之監測及分析」，國立臺灣大學生物環境系統工程學研究所博士論文。

10.林美聆、游繁結、林炳森、范正成、王國隆（2000），「集集震後土石流二次災害危險性之評估」，地工技術，81：97-104。

12.范正成、吳明峰、彭光宗(1999)，『豐丘土石流發生降雨臨界線之研究』，地工技術，第74期，pp.39-46。

14.范正成、劉哲欣、吳明峰(2002)，“南投地區土石流發生臨界降雨線之設定及其於集集大地震後之修正”，中華水土保持學報，第33卷第1期，pp.31-38。

11.范正成、吳明峰(2001)，『一級溪流土石流危險因子及其與臨界降雨線之關係』，中華水土保持學報，第32卷，第3期，pp.227-234。