以蒙地卡羅模擬探討非飽和土壤異質性對入滲之影響

本文利用蒙地卡羅模擬法探討非飽和土壤異質性對入滲之影響。本研究建立一非飽和土壤水數值模式，模式經驗證後，應用於土壤水分入滲模擬，本文以蒙地卡羅法產生土壤特性隨機參數，利用數值模擬結果探討非飽和土壤異質性之影響，並與定率模擬結果比較。模擬結果顯示，土壤水分入滲受土壤異質性影響會有減緩之趨勢，土層中存在不同透水性之土壤時，垂直入滲率受到透水性較小土壤之影響較鉅。經由序率模擬，可得到入滲率之平均值、涵蓋範圍及機率分布型態，研究結果顯示入滲率在異質性土壤中之機率分布型態符合常態分布。本研究另以序率模擬之入滲率累積機率曲線探討定率模擬及經驗公式所求得之入滲率，結果顯示定率模擬及經驗公式高估入滲率之機率相當高。

關鍵字

非飽和土壤；異質性；地下水；入滲；蒙地卡羅模擬

並列摘要

This paper investigates the influence of unsaturated soil heterogeneity on infiltration by Monte Carlo simulation. An unsaturated groundwater flow model is developed; the calibrated model is then applied to seepage flow simulation. This study adopts Monte Carlo method to generate stochastic parameters of soil characteristics and investigate the influence of soil heterogeneity on infiltration. The results of stochastic simulation are compared with those of conventional deterministic approach. The results reveal that soil heterogeneity inhibits seepage flow. The seepage flow is governed by the soil with less permeability rather than that with greater one as various soil classes exist. The range, mean value, and probability distribution of the infiltration rate can be obtained with stochastic simulations. It is revealed that the infiltration rate is normal-distributed. The cumulative probability curves of the infiltration rate are used to investigate the results of deterministic simulation as well as empirical formula. It is indicated that the probability for the deterministic simulation and empirical formula to overestimate infiltration rate is rather high.

並列關鍵字

Unsaturated soil ； Heterogeneity ； Groundwater ； Infiltration ； Monte Carlo simulation

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