Browsing by Author "Yang, Chao-Chung"

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An Integrating Approach for Conjunctive-Use Planning of Surface and Subsurface Water System
(2011-01-01)
Chang, Liang-Cheng
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Ho, Chih-Chao
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Yeh, Ming-Sheng
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Yang, Chao-Chung
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土木工程學系
This study proposes an integrated approach to assess the performance of a conjunctive-use surface and subsurface water system. System dynamics serves as the main framework of the proposed conjunctive-use model, simulating the interaction between surface and subsurface water and the impact of various conjunctive-use alternatives on the system as a whole. This study assumes natural groundwater recharge as a water source to the system, and estimates its volume using geographic information system (GIS) tools, a groundwater simulation model (MODFLOW), and a parameter identification model (UCODE). This study assesses various conjunctive-use alternatives and analyzes the frequency of water shortage to illustrate how the recharge rate affects water supply reliability under the conjunctive-use framework. Simulation results indicate that conjunctive-use with artificial recharge indeed reduces the frequency of extreme water shortages. Results also reveal that artificial recharge is necessary to maintain groundwater conservation without overusing river flow. Although this study focuses on southern Taiwan, the proposed concepts and procedure are applicable to other areas with a similar conjunctive-use framework.
Application of system dynamics with impact analysis to solve the problem of water shortages in Taiwan
(2008-11-01)
Yang, Chao-Chung
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Chang, Liang-Cheng
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Ho, Chih-Chao
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土木工程學系
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Department of Civil Engineering
The major two concerns for planning a successful water strategy in Taiwan are the modification of water shortages and a total financial cost, construction, and operating costs. Therefore, the purpose of this study is to formulate an appropriate strategy to seek a balance between mitigating water shortages and total financial cost. Accordingly, we propose a process for combining a system dynamics approach and impact analysis to evaluate water strategy systematically and quantitatively. Water shortages and total financial cost are referred to, as governments are responsible for the management of regional water resources. System dynamics is one approach that can help decision makers build a simulation model of a complex water supply system. The value of a water shortage and total cost to all possible planning strategies for future water demand can be obtained from system dynamics model simulation. The content of proposed impact analysis is used to design indexes that are able to indicate (1) the severity of a water shortage and (2) total financial cost. Examining the performance of proposed indexes, we can understand the interactive impact between these two objectives in every strategy and then select appropriate strategies. Finally, the effectiveness of the proposed methodology is verified by solving a problem of water shortage and total financial cost in central Taiwan.
Multi-objective Planning for Conjunctive Use of Surface and Subsurface Water Using Genetic Algorithm and Dynamics Programming
(2009-02-01)
Yang, Chao-Chung
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Chang, Liang-Cheng
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Chen, Chang-Shian
;
Yeh, Ming-Sheng
;
土木工程學系
The consideration of fixed cost and time-varying operating cost associated with the simultaneous conjunctive use of surface and subsurface water should be treated as a multi-objective problem due to the conflicting characteristics of these two objectives. In order to solve this multi-objective problem, a novel approach is developed herein by integrating the multi-objective genetic algorithm (MOGA), constrained differential dynamic programming (CDDP) and the groundwater simulation model ISOQUAD. A MOGA is used to generate the various fixed costs of reservoirs' scale, generate a pattern of pumping/recharge, and estimate the non-inferior solutions set. A groundwater simulation model ISOQUAD is directly embedded to handle the complex dynamic relationship between the groundwater level and the generated pumping/recharge pattern. The CDDP optimization model is then adopted to distribute the optimal releases among reservoirs provided that reservoir capacities are known. Finally, the effectiveness of our proposed integrated model is verified by solving a water resources planning problem for the conjunctive use of surface and subsurface water in southern Taiwan.
Multiobjective planning of surface water resources by multiobjective genetic algorithm with constrained differential dynamic programming
(2007-11-01)
Yang, Chao-Chung
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Chang, Liang-Cheng
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Yeh, Chao-Hsien
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Chen, Chang-Shian
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土木工程學系
Owing to the conflict encountered between the two objectives of fixed cost in reservoir installation and operating cost in time-varying water deficit, multiobjective planning of surface water resources is a difficult job. Instead of combining these two objectives into just one objective using the weighting factor approach, this investigation proposes a novel method by integrating a multiobjective genetic algorithm (MOGA) with constrained differential dynamic programming (CDDP). A MOGA is employed to generate the various combinations of reservoir capacity and estimate the noninferior solution set. However, applying this algorithm to solve the dynamics of the operating cost, the number of variables increasing with time will dramatically increase the use of computational resources. Consequently, the CDDP is herein adopted to distribute optimal releases among reservoirs to satisfy water demand as much as possible. Next, the effectiveness of the proposed methodology is verified by solving a multiobjective planning problem of surface water in southern Taiwan. This real application demonstrates that MOGA can be linked with CDDP to resolve a complex water resources problem. Additionally, the ability of MOGA on addressing multiple objectives simultaneously without converting to a weighted objective function provides the opportunity for significant advancement in multiobjective optimization. Finally, this investigation also proposes three suitable strategies of reservoir construction to decision makers With budget concerns through the analysis of all noninferior solutions.
Policy assessment for conjunctive-use of surface and subsurface water using system dynamics
(2007)
Ho, Chih-Chao
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Yang, Chao-Chung
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Chang, Liang-Cheng
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Leung, Wai-Yi
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Yeh, Ming-Sheng
The conjunctive use of surface and subsurface water is used commonly for offering stable supplies in water resources management. Owing to the water distribution problem is spatial dependency and temporal dependency, the new water resource intervention make system getting more complicated. Conventionally, optimization distribution model' has been taken to solve such complex allocation problem. However, the determination of constraints and objective functions must be under the settled system and the resolving process is subject to the selected optimal methodology. Hence, 'optimization distribution model' is difficult to solve the problem of capacity expansion and system expansion caused by policy postponed This study provides a powerful object oriented simulation model, system dynamics, alternative to optimization distribution model for representing complexity and variation of systems and analyzing their dynamics behavior. This approach uses a perspective based on stock-flow diagram which exploit system structure and operation procedures simultaneously hidden in modelers mind.. Finally, a case study in southern Taiwan is adopted herein to show the flexible and versatile of proposed approach.
The application of system dynamics to water resources sustainable use for the Kaopin river basin
(2005)
Yang, Chao-Chung
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Shan, Hsin-Yu
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Lee, Han-Keng
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Hsu, Shao-hua
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Chen, Tze-Wei
The demand for water in Kaopin river basin has increased significantly in recent years owing to industrial growth and increasing living standards. This situation not only raises the crisis of water deficit but also brings serious problem of water pollution. Hence, any suitable strategy is required to consider simultaneously the effect between water quantity and water quality. A system dynamics model is including the critical feedback structures in the system. Simulating the model shows the effect of the system structure on policy interventions. Therefore, system dynamics is well-suited to analyzing problems whose behavior is governed by feedback relationships and which have a long-term time horizon. Finally, this study addressed two major problems: 1) water deficit, 2) water pollution and then makes the appropriate strategy to avoid the huge impact between water deficit and water pollution and also prohibit the time delay of strategy.
The interval estimation of parameters for Back-Propagation Network to flood discharge forecasting
(2006)
Chen, Chang-Shian
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Yang, Chao-Chung
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Liu, Chin-Hui
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防災與水環境研究中心
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Disaster Prevention and Water Environment Research Center
This study employs a Back-Propagation Network as the main structure in flood forecasting to learn and demonstrate the sophisticated nonlinear mapping relationship. A Self Organizing Map network with classification ability is also applied to the solutions and parameters of BPN model in the learning stage, to classify the network parameter rules and obtain the winning parameters. Hence, hydrologic data intervals can then be forecasted, with the outcomes from the previous stage used as the ranges of the parameters in the recall stage. Finally, the effectiveness of methodology is verified by solving a flood discharge forecasting problem in the Wu-Shi basin of Taiwan.