應用冪次定律於崩塌地特性之探討－以石門水庫集水區為例

Evaluation of Landslide Properties in Shihmen Reservoir Watershed by Means of Power-Law Method

汪彙信(Hui-Hsin Wang)

指導教授 ： 曾志民

長榮大學/管理學院/土地管理與開發學系(所)/碩士(2010年)

https://doi.org/10.6833/CJCU.2010.00141

摘要

摘要
本研究將石門水庫集水區分成七個子集水區，將各區10場颱風暴雨事件之新增崩塌地進行規模頻率分析，分析成果顯示新增崩塌地數量於0.01公頃以上亦有小規模之發生多、大規模之發生少的冪次定律特性。因此將崩塌地規模頻率之參數κ、β於以探討崩塌地區域環境特性，於十次颱風事件新增崩塌地規模頻率中，定義出κ、β值之意涵，分別代表規模、單位面積發生頻率。
兩者對應至岩性區域特性，可得知堅硬砂岩與頁岩為次數多規模小，板岩為崩塌規模大次數較為不定，變質砂岩則為次數少規模小；再藉κ、β值與崩塌坡度探討，可發現崩塌坡度最小值(最低坡度臨界值)與兩參數有關聯，κ值越大坡度臨界值越小，β值越大坡度臨界值也越小。藉此可歸納出七個子集水區之崩塌特性如下：秀巒與玉峰子集水區崩塌規模大乃因其岩性區域皆以板岩居多，次數多則受其崩塌地所在坡度臨界值較小之故；高義子集水區因區內多為堅硬砂岩與頁岩故崩塌規模小，而稜角集水區則因區域多變質砂岩，所以崩塌規模亦小，此兩區又因崩塌坡度臨界值較高所以頻率次數少；三光子集水區區內多數是堅硬砂岩與頁岩所以頻率次數多規模也較小，但因崩塌坡度臨界值關係，當事件崩塌之坡度臨界值較小則規模與頻率次數皆會較大較多。霞雲子集水區多座落於板岩所以有時崩塌規模較大，但因崩塌坡度臨界值不定，所以此集水區只能就單場颱風暴雨事件之崩塌規模頻率參數κ、β值來判斷其崩塌特性；石門子集水區因其岩性多屬堅硬砂岩與頁岩，其崩塌規模較大，但因受崩塌坡度臨界值影響，頻率次數於臨界值大時，即會較小。
七個子集水區於其地理環境特性中探討出，各子集水區之新增崩塌地規模頻率特性，不僅有助於七個子集水區崩塌地發生條件之探討，更能幫助相關單位於七個子集水區治理方針之擬定。而將每個集水區之κ、β參數代入Hovius (1997)所推演之崩塌體積公式，其算出之崩塌體積相較於前人，以一整年完整崩塌地之推求小許多，雖加上表土沖蝕量之估算，仍發現推算之泥砂量較實測淤積量小，日後若能藉由參數代表值進一步推求新增崩塌體積，配合泥砂遞移與表土沖蝕，將更能與實測淤積量進行比對探討。

關鍵字

水庫集水區 ； 冪次定律 ； 崩塌地

並列摘要

Abstract
In this research we divide the Shihmen reservoir watershed into seven sub basin, and with 10 typhoon storm events of new landslide area to analyze scale of frequency. The results accorded with power law’s feature reveals that the number of new landslide more than 0.01 hectares has small scale but high frequency and with large scale but low frequency. Hence this research applied parameter κ and β of landslide scale frequency to discuss surroundings characteristic of landslide region. And with new landslides of 10 typhoon storm events we define the meaning of κ and β respectively represent of scale and unit of area occur frequency.
κ and β response to the feature of lithologic character, sandstone and shale has small scale with high frequency; meta greywacke has small scale with low frequency; slate has large scale but it’s frequency is hard to classify. Applying the κ、β with landslide slope, we can find that minimum landslide slope (critical value of minimum landslide slope) has the relationship between κ and β. The relationship indicate that the larger of κ and β the smaller of critical value of slope. Via this relationship we conclude landslide character of seven sub basins as follows: Hsiuluan and Yufeng sub basin has large landslide scale due to lithologic character is slate and with the high frequency is because of the critical value of landslide slope much small. In Kaoi and Leng-Chiad sub basin the lithologic character in most area is greywacke、shale and meta greywacke respectively hence their landslide scale are small. And in these two sub basin the critical slope of landslide is high results in low frequency. The lithologic character of Sankuang sub basin in most area is sandstone and shale result in small scale with high frequency. But due to the critical value of landslide slope, when the events with small critical landslide slope the frequency and scale become much more and bigger. Xiayun sub basin locate in the slate region with the result that sometimes the landslide scale is much bigger. But owing to critical landslide slope was not sure in this sub basin use single event to calibrate landslide feature. In Shihmen sub basin most lithologic character is belong to sandstone and shale result in landslide scale much bigger but affected by the critical landslide slope hence when critical slope is higher the slump frequency become much small.
In the seven sub basin with their geographic environment character and new landslide’s scale and frequency character in each sub basin not only just help for landslide occur condition but also helpful for related organization or department to design watershed management planning. Applied empiric formula of landslide volume by Hovius (1997) and substitute κ、β of each sub basin to estimate landslide volume. Using the whole year occurred landslide to estimate landslide volume and add soil surface erosion volume but the outcome compare with former research still less than measured sediment volume. Suppose that someday via parameter of representative value to estimate new landslide volume and cooperate with sediment transport and soil surface erosion volume will help for compare with measured sediment deposit volume.

並列關鍵字

reservoir watershed ； power law ； landslide

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