Parameter Calibration in A Process-Based Soil Depth Estimation Model - Assuming Local Steady State
Date Issued
2006
Date
2006
Author(s)
Chiang, Shou-Hao
DOI
zh-TW
Abstract
Soil thickness is one of the fundamental components in many hydrological and slope stability models. Since landform critically influences many slope processes, soil thickness which is related to various slope processes is also highly affected by topography. In this study, a soil production function is coupled with a simple diffusion model to form a soil-thickness prediction model. The Yang-Ming-Shan National Park is chosen as a study area to test the validity of the model.
It is assumed that the topography has not had any drastic change during the simulation time period, the soil is moving downhill according to simple creep law, which sets the transport flux equal to a linear function of local slope gradient, and its transport rate is in equilibrium with the soil production rate at ridge lines. Model parameters are calibrated under this local steady-state assumption, and used to estimate the soil thickness within the study area. The results show that soil depth in the study area ranges from 0 to 2 meters, and spatial variation is controlled by topographic curvature. Field verification shows that the model performs well on convex, law gradient, and upper part of hillslopes. It is discovered that in those poorly modeled area, slope processes other than diffusion prevail which bring about the disparity in model prediction.
Generally speaking, assuming local steady state facilitates parameter calibration and improves model’s applicability. However, in order to extend the model application to the entire hillslope, it is essential to incorporate other processes in the model.
Subjects
土壤生成函
擴散模式
簡單潛移
局部穩定平衡
參數率定
soil production function
diffusion model
simple creep
local steady state
parameter calibration
Type
thesis
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