IDENTIFICATION OF INFILTRATION PROCESS IN RAINFED RICE FIELD SOILS
Soils of rainfed rice fields have unique characteristics.Inland valleys are extensively found in West African savannas.and their hydromorphic valley bottoms are intensively used for rainfed rice-culture during rainy seasons when become wetlands.Data of rainfall and soil moisture are perennially collected in a study site located in Northern Region of Ghana.The soil of the site is classified as Dystric Planosols.The soil moisture retention curve at a depth of the soil is identified from observed volumetric water content and matric head.Since the soil is variably saturated.it is important to clarify abruptly changing hydraulic properties of the soil near saturation.A bimodal model including eight empirical parameters turns out to be suitable for this purpose.The vertically one-dimensional Richards equation is considered to reproduce infiltration process of rainwater into the soil.The saturated water content，one of the empirical parameters，and saturated hydraulic conductivity are assumed to be functions of the depth of soil.Then.the finite element method is applied for solving the Richards equation to simulate the process.The simulation results are in good accordance with actually observed data.The methodology developed here serves as a tool for comprehending formulation process of the wetlands at early stages of rainy seasons.
Yong-qiang Xu A.H.M.B.Alam Hidetoshi Kohashi
Construction Technology Research Team.Public Works Research Institute,Minamiharal-6，Tsukuba City,Iba Graduate School of Agriculture，Kyoto University,Kitashirakawa-oiwake-cho，Sakyo-ku，Kyoto，606-8502 Jap Construction Technology Research Team，Public Works Research Institute，Minamiharal-6，Tsukuba City，Iba
国际会议
High-level International Forum on Water Resources and Hydropower(第一届国际水利水电高层论坛)
北京
英文
383-388
2008-10-17（万方平台首次上网日期，不代表论文的发表时间）