未飽和土層中入滲水流之運動分析及研究

Flow Analysis In Unsaturated Zones

溫志超(Jet-Chau Wen) ； 楊志盛(Jr-Sheng Yang)

《中華水土保持學報》 31卷3期 (2000/09) Pp. 205-216

https://doi.org/10.29417/JCSWC.200009_31(3).0004

摘要

本研究目的爲利用理查方程式解析及數值解模擬，求得在未飽和均質土壤中垂直入滲的水流運動行爲。本研究重新推導Srivastava及Yeh（1991）所導出之均質土壤中水流運動過程之解析解，並以牛頓迭代法求解。另外，以顯性及隱性有限差分法進行數值求解，並將理論解與數值解進行比較。此外研究發現均質土壤在濕潤與排水過程中，其水力行爲可藉由壓力水頭、含水量及流量之變化情形加以描述。在相同的飽和水力傳導係數和入滲的情況下，當土壤之土壤孔隙分佈參數α較小時，則水流較易入渗到達地下水位面；而在相同的土壤孔隙分佈參數和入滲的情況下，當飽和水力傳導係數較大時，水流亦較快入滲至地下水位面，進而達到穩定狀態。

關鍵字

未飽和土壤 ； 土壤孔隙分佈參數 ； 入滲量 ； 含水量 ； 壓力水頭

並列摘要

The purpose of this study is to simulate the hydraulic behavior of the flow process in homogeneous unsaturated soils with analytical and numerical solutions of the Richards equation. The analytical solution of the flow behavior reported by Srivastava and Yeh (1991) is derived in t he study. The explicit and implicit finite difference methods of the numerical solutions were used. It was found that, with the appropriate conditions, the explicit method would be easier to use than the implicit method. Finally, the analytical solution was compared with the numerical solutions. It was shown in the study that the hydraulic behavior of the wetting and drainage processes in the unsaturated soil was related to the pressure head, water content, and flow. With the constant saturated hydraulic conductivity coefficient and the infiltration, the smaller the pore-size distribution was, the easier the water infiltrated. It was also indicated that the flow of infiltration increased with an increase in the hydraulic conductivity coefficient under a constant pore-size distribution and infiltration rate. Consequently, the flow of infiltration reached the steady state faster.

並列關鍵字

unsaturated soil ； pore-size distribution ； infiltration ； water content ； pressure head