台灣西南部泥岩地區災害的處理對策

Disaster countermeasures of mudstone areas in southwestern Taiwan

李吉雄(Jyi-Hsiung Lee) ； 張則安(Ze-an Zhang)

《中華防災學刊》 12卷1期 (2020/03) Pp. 9-34

摘要

台灣西南部泥岩潛在地區分布在中央山脈與平原地區間的麓山帶，北起雲林縣古坑鄉，南經嘉義縣、市、台南市，達高雄市旗山區止，在此遼闊的山坡地經長期的不合理土地利用，導致水土失衡，覆蓋於泥岩層上厚薄不一的土壤層漸漸流失，泥岩露頭呈現，廣大的裸露崩塌形成寸草不生的白堊土惡地形，俗稱月世界。泥岩岩性主要為細粒的泥岩、頁岩、粉砂岩及砂岩等，另有一些岩層介於上述岩性之間，由於泥岩所占比例最多，故統稱泥岩。此種岩層新鮮時呈青灰色，故又稱青灰岩（當地農民稱海人土），泥岩不具層理，節理亦不發達，膠結力差，乾季時堅硬如石，經風化後表層龜裂剝落成洋蔥狀，遇雨裂解成泥成土，顆粒微小構造細密，為膨脹性黏土，具回脹性，屬重鹼性土壤，植物根系難入，不易成長。由於泥岩顆粒細微、泥層甚厚、透水性差，地區內缺乏地下水，在鄰近泥岩區附近興建水庫蓄水，解決區域的民生用水和灌溉農田。由於泥岩容易沖蝕，每當雨季一到，颱風豪雨造成河川及水庫的淤積及道路邊坡沖蝕，致使各項公共設施造成災害，為處理這些問題提供相當措施，作為整治的參考。

並列摘要

Potential mudstone areas in southwestern Taiwan are located in the foothills between the Central Mountains and the plains. Long and unreasonable land use in this vast hillside leads to soil and water imbalance. The thin mudstone layer is gradually lost and outcrop appears, and the vast bare collapses to form the grassy and chalky bad terrain, commonly known as the Moon World. Mudstone lithology is mainly fine-grained mudstone, shale, siltstone, sandstone, etc. Mudstone has no stratification and joint, and has poor cementation. It is as hard as stone during the dry season. After weathering, the surface cracks and peels into onions. It will crack into mud and soil when it rains, with fine particles and fine structure. It is an expansive clay and belongs to heavy alkaline soil that plant roots are difficult to penetrate the soil and grow up. Typhoons and heavy rains cause siltation of rivers and reservoirs, and erosion of road slopes, causing disasters to various public facilities. Provide considerable measures to deal with these problems, as a reference for countermeasures.