蓮華池林地未飽和土壤水力傳導度特性之研究

Study onthe Hydraulic Conductivity Properties of Unsaturated Forest Soilin Lienhwachi Area

黃襦慧(Juhui Huang)

指導教授 ： 陳明杰

國立臺灣大學/生物資源暨農學院/森林學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01562

摘要

本論文係就林地未飽和土壤的水力傳導度進行探討，選取蓮華池五號集水區東向坡為試驗地，就山頂、山腹和山谷分別各取4點，每一點取3個深度。研究方法是以張力滲透試驗儀在不同壓力水頭條件下，進行林地滲透試驗，並比較不同位置、深度之水力傳導度的差異。
並採取不擾動土樣進行室內土壤物理試驗，對照現地滲透試驗的結果，來說明土壤之孔隙率、孔隙組成、含水率等對水分滲透的影響。以及因土壤含水率、孔隙率、大孔隙比例的不同，或遇有植物細根系的干擾，林地水力傳導度的變化。
試驗結果顯示，蓮華池林地的水力傳導度在不同剖面、位置時，並無顯著差異；但在測定不同深度的情形之下，水力傳導度呈現明顯的差異，且隨土壤深度增加而減小的趨勢。其次，隨著負壓力水頭增大，表層土壤的不飽和水力傳導度大幅降低，而深度20cm和深度40cm則變化較為緩和。由於深層土壤孔隙率較小，土壤結構未若表層疏鬆，故深層土壤的滲透性較差。再者，壓力水頭減小時，土壤中部分孔隙被空氣填滿，故水力傳導度下降，此一現象在大孔隙比例較高的表層土壤特別明顯，而主要利用小孔隙毛管作用進行水分移動的深層土壤，則不易被影響。

關鍵字

水力傳導度 ； 張力滲透試驗儀

並列摘要

This study applied on the hydraulic conductivity of the unsaturated forest soil in the Lien-Hwa-Chi area, and compared the deviation in hydraulic conductivity among different locations and depths. It’s helpful to understand the effective of water contain, soil pores, rough pores and roots of plants.
The study area was located on the eastern slope in Lienhwachi watershed No.5. Measure the forest soil saturated hydraulic conductivity in different gradient, and choose 4 points, 3 depths on ridge, hillslope and valley. The study used the Tension Infiltrometer to measure the hydraulic conductivity and excavated undisturbed soil for physical test. It could tell the effectives of hydraulic conductivity by compared both of the results.
These results show that there was no deviation in hydraulic conductivity among different locations but depths. The surface soil is loose and the pores are less in deeper soil, so the hydraulic conductivity becomes smaller within the increasing of depth.
The hydraulic conductivity decrease if part of soil pores filled with air, and the gradient become smaller. This situation usually happened in the surface soil. There was no significant difference in deeper soil because the water movement here depended on micro pores.

並列關鍵字

hydraulic conductivity ； Tension Infiltrometer

參考文獻

5、林俐玲、陳佩松(1993) 坡面表土飽和水力傳導度之推估。中華水土保持學報24(2)：119-130。

4、吳耀琪(1990)不同覆蓋林地未飽和帶土壤水分變化之研究。國立台灣大學森林學研究所碩士論文。

12、陸象豫、唐凱軍、古秀宇、黃惠雪(2000)林業試驗所各林區氣候狀況。台灣林業科學15(3)：429-440。

14、蔡義誌(2001)坡地單一土層和複合土層水力傳導度之研究。國立中興大學水土保持學研究所碩士論文。

18、Garder, W.R., 1958, Some Steady state solutions of unsaturated moisture flow equations with application to evaporation from a water table, Soil Science 85:228-232.