均匀降雨下有限厚土层之植生地表水理分析-中华水土保持学会.PDF

中華水土保持學報, 44(1): 11-22 (2013) 11 Journal of Chinese Soil and Water Conservation, 44 (1): 11-22 (2013) 均勻降雨下有限厚土層之植生地表水理分析 胡秀怡 謝平城 * 摘 要 本研究將流場分成均質水層、水-草混合層和有限厚透水土層 (以下簡稱水層、草 層、土層) 。考量坡地表面透水，且地表下的水流為孔隙介質流，因此地表水流速度不為零。以 Navier-Stokes 方程式來描述水層之流況，將草、土兩層中之流體視為孔隙介質流的運動，且引 入多孔介質層流模式加以描述之，最後搭配 Runge-Kutta 法而求得其半解析解。文中分成非浸 沒型 (水深不及草高) 、浸沒型 (水深漫過草高) 與混合型三種類型討論，並探討坡度、降雨強 度、土層厚度和植株直徑等因子對流況之影響，以期研究成果在環境和生態工程之設計及地表 水的管理上能有所助益。 關鍵詞：孔彈性介質理論、漫地流、均勻降雨、植生。 Hydraulic Analysis of Water Flow Passing over Vegetated Areas with Finite Thick Soil Layers under Uniform Rainfall * Siou-Yi Hu Ping-Cheng Hsieh ABSTRACT To understand the effect of rainfall on water flow down a slope, the flow region was divided into three layers—the homogenous water layer, mixed water-plant layer and finite thick soil layer. The flow of the water layer was governed by the Navier-Stokes equations. The vegetation and soil layers were both regarded as porous media and the laminar model modified from Biot’s the- ory of poroelasticity was applied. The semi-analytical solutions were then obtained via the Runge-Kutta method. Three patterns--submerged vegetation, emergent vegetation and sub- merged-emergent vegetation--were discussed. Additionally, the effect of slope, rainfall intensity, thickness of soil layer and plant diameter on the flow were also discussed. The results are believed to be helpful in environmental and ecological engineering design and surface water management. Key Words : Poro-elasticity theory, overland flow, uniform rainfall, vegetation.