三維空間中砂丘的稜線輸砂量與背風面的積進之關係

Abstract

本研究致力於探討沙丘背風面的堆積前進與稜線輸砂量分布之間的關係，藉由理論配合實驗以及現地測量結果來模擬沙丘稜線輸砂量。簡化假設的理論將三角洲的演進推演到三維空間中的沙丘的背風面，是一個更廣泛性的理論，同時也建立數值模型，來模擬實驗的新月形沙丘和現地沙丘的稜線書砂量分布並以簡單的拋物線型稜線來驗證數值模型的正確性。透過渠槽實驗，使用雷射掃描將新月形沙丘的形貌量化並且記錄其演化過程，從新月形沙丘的演化實驗可以發現拋物線型稜線的模擬有許多相符合的定性結果。另外，本研究應用無人載具搭配影像測量重建頂頭額沙洲的高解析度三維模型，從兩次不同時間的測量分析現地沙丘稜線的移動，以供數值模型進行稜線書砂量的模擬。

The purpose of the research is to explore the relationship between dune slip face progradation and sand flux with simplified theory, experiment and field survey. Based on the concept of delta front progradation, the theory of dune slip face progradation is generalized to account for greater freedom. To apply the theory we derived, the numerical model for simulation of sand flux is established. The distribution of sand flux can be calculated with brinkline shape, the angle of repose and the moving velocity of brinkline. With a simple parabolic shape of brinkline, different shape of dunes can be illustrated and the simulation model can be verified. Experiment of dune, which is conducted under water, can reveal the evolution efficiently because the viscosity of water is much higher than air. The barchan dune experiment, which is particularly accessible for experimental investigation, provides well-controlled conditions to test the simulation model. In addition, some experiment results correspond to the simulation of parabolic brinkline. The dune shape in Dingtoue Sandbank is successfully measured with Unmanned Aircraft Vehicle (UAV) and the observation result is applied to the simulation model as a complex condition. This thesis shows the preliminary research from three kinds of methods and we leave several future works to be expected.