A Study on the Effect of Steady and Unsteady Rainfalls on soil Infiltration under Different Initial Water Contents

• Main Authors: Tzung-Yuan Wang, 王宗原
• Other Authors: Chu-Hui Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/32409065336866288860

碩士 === 中國科技大學 === 土木與防災應用科技研究所 === 94 === The estimation of infiltration can be obtained by means of experiment and site measurement or by the mathematical formula of hydrologic physics mechanism for soil. In the infiltration problem of unsaturated layer with a specific condition and soil surface water supply varied with time of soil moisture. The Richards’ equation can be used as the governing equation to solve the problem theoretically. Generally, the analysis solution of soil infiltration would simplify the initial and boundary conditions. But under the natural condition, the initial soil water content varied with the soil depth and the boundary condition of soil surface varied with the rainfall intensity as well. These natural factors of time and space variation increase the difficulty of solving the Richards’ equation. Lee (2004) proposed a solution method with the residual difference of mass conservation equation established by Celia (1990). By means of the method, this article obtained the unique soil property, with a constant of saturated hydraulic conductivity coefficient Ks, of saturated soil layer under the condition of steady state and non-steady state rainfall. Also consider the transfer phenomenon of soil surface water flow. The variation of Ψ value can be obtained by substituting the simulated results into the Green & Ampt infiltration formula. With the results of Ψ value, we will establish the relationship of variation volume Δθ of water content and infiltrative depth L acquired by Green & Ampt infiltration formula. The infiltration condition can be obtained by the proposed relationship as fast as possible.