Establishment and Application of Numerical Model Calibration Method for Groundwater Flow Near Infiltration Gallery – A Case Study of Lin-Bien River
Date Issued
2015
Date
2015
Author(s)
Lo, Chen-Yu
Abstract
This thesis aims to establish a numerical model calibration method for groundwater flow near infiltration gallery, and apply this method to an in-situ case of infiltration gallery in Lin-Bien River; in order to highlight the usage of the method had built. The numerical model calibrating method established by this thesis includes calculating groundwater balance near infiltration gallery, building numerical model and formulating optimization model for parameter verification. First, by calculating system groundwater balance, we will realize the ground surface boundary recharge, upstream inflow quantity, downstream outflow quantity and water intake of infiltration gallery. The method computes the quantity of recharge through every system boundary, the rate of change of system water storage and calculates river and rainfall recharge by continuity equation. Second, build a numerical model and its optimization model for parameter verification; solve the best combination of soil parameter, depth/infiltration recharge of river and rainfall infiltration proportion. Above-mentioned optimization model for parameter verification will solve by iterative method with a more efficient trial and error method, until objective function is minimum. On the other hand, delete the mesh to simulate the space in the infiltration gallery, and conceptualize it into a form of open channel, the right, left hand and bottom side are concrete material, and top side is decide as different filter layer. Given head condition are set up in the concrete region to simulate the gravity controlled condition, after the simulation is finished, summation the flux on each node to get the infiltration gallery discharge. This thesis was applied to the process to groundwater system near infiltration gallery of Lin-Bien River. According to calculating system groundwater balance result, during 2010/01/01~2010/09/05, the total recharge is 41.9 million tons, river and rainfall infiltration recharge are 98.9% among them, upstream boundary recharge are 1.1% among them. Total out flow is 41.3 million tons, downstream outflow are 35.6% among them, water intake of infiltration gallery are 64.4% among them. According to the result of calibrating groundwater flow model near infiltration gallery of Lin-Bien River, during dry and rainy season in 2010/01/01~2010/09/05, RMSE of observing well C are 0.17 m and 0.08m respectively, CE are 0.98 and 0.998 respectively, CC are 0.99 and 0.999 respectively. RMSE of observing well D are 0.27 m and 0.14m respectively, CE are 0.89 and 0.98 respectively, CC are 0.98 and 0.99 respectively. RMSE of observing well E are 0.112 m and 0.114m respectively, CE are 0.98 and 0.99 respectively, CC are 0.98 and 0.996 respectively. RMSE of observing water intake of infiltration gallery are 5,465(cmd) and 2,958(cmd) respectively, CE are 0.94 and 0.99 respectively, CC are 0.97 and 0.995 respectively. The total recharge is 4.28 million tons, river and rainfall infiltration recharge are 99.2% among them, upstream boundary recharge are 0.8% among them. Total out flow is 42.9 million tons, downstream outflow are 41% among them, water intake of infiltration gallery are 59% among them.
Subjects
Lin-Bien river
Infiltration gallery
Horizontal pipe
Water balance
Finite element method
Unsaturated soil
Steady state
Transient
Type
thesis
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