Browsing by Author "Ho, Chih-Chao"

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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.
Applying Multiobjective Genetic Algorithm for analyzing the trade-off of water use return among different sectors
(2008)
Ho, Chih-Chao
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Chang, Liang-Cheng
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Leung, Wai-Yi
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土木工程學系
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Department of Civil Engineering
The water use struggle among different sectors is a serious water resource problem during the drought in Taiwan. The irrigational use water is frequently been transferred to industrial use water due to its lower economic value, although agriculture sector will be compensated from other water use sectors when water transfers occur, the reasonable amount of compensation is still controversial How to obtain a quantitative support for helping different water use sectors to achieve an acceptable resolution is vital. Therefore, this study develops a multiobjective model of water resource management to evaluate the trade-off among different water use sectors. The shortage index is used to perform the water deficit of different water use sectors. The model integrates operating rules, stepwise linear programming (SLP) and multiobjective genetic algorithm (MOGA) to solve a mutiobjective regional water allocation problem. Moreover, simulation results clearly demonstrate the trade-off relationship between shortage indexes for agriculture and that for industry. The computed trade-off curve, non-inferior solutions, is a valuable quantitative support for the transfer negotiation of water use among various sectors.
Applying Multiobjective Genetic Algorithm to Analyze the Conflict among Different Water Use Sectors during Drought Period
(2010-09-01)
Chang, Liang-Cheng
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Ho, Chih-Chao
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Chen, Yu-Wen
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土木工程學系
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Department of Civil Engineering
Water deficits often occur during the drought season and may cause water conflicts among various water use sectors. The reservoir rule curve operation is commonly used to avoid extreme water shortage during droughts in Taiwan. When applying the rule curve operation, the water supply discounting ratio for different sectors implies a trade-off of water deficit impact among sectors. This study therefore develops a multiobjective water resource management model to evaluate the trade-off curve of water deficit impact between irrigation and public sectors to facilitate negotiation between the sectors for obtaining acceptable discounting ratios. The study uses the shortage index to assess water deficit impact. The proposed model integrates operating rules, the stepwise optimal water allocation model, and the convex hull multiobjective genetic algorithm to solve the multiobjective regional water allocation planning problem. The computed trade-off curve, noninferior solutions, provides relevant information to facilitate negotiating water-demand transfer. The results reveal that when decision makers prefer specified water use, the discounting ratio of another competing water use at the low buffer zone should be limited on the lower bound.
Determining an Optimal Action Portfolio for Water Resource Management by Using Stochastic Programming
(2017-07-01)
Ho, Chih-Chao
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Pan, Chen-Che
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Chang, Liang-Cheng
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土木工程學系
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Department of Civil Engineering
A regional water management system always contains long-term and short-term actions in practice. The uncertainty of short-term actions increases great complexity for evaluating the performance of action portfolio comprised with long-term and short-term actions. Developing an efficient methodology to define a cost-effective action portfolio is an important task. Hence, this study develops a novel decision model, the Stochastic Programming with Recourse Decision Model (SPRDM), to compute a cost-effective action portfolio. The effectiveness of SPRDM is verified by address a problem of water shortage and financial cost in Taoyuan City, Northern Taiwan. The results shown adding Kaotai Reservoir alone can fulfill the Taoyuan demand most of the time, and the remaining extreme water shortage events can be addressed by short-term and irrigation management actions additionally. When drought duration of water shortage event is longer than 200 days, using irrigation management action to address water deficit has lower expected costs than other short-term actions do. Although the study focuses on Northern Taiwan, the proposed model is applicable to other areas with an integrated water resources management framework.
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 Decision Model for Integrated Water Resources Management
(2013)
Ho, Chih-Chao
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Chang, Liang-Cheng
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Pan, Chen-Che
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Tsai, Chan-Ming
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Tu, Yi-Te
The proposed strategies of Taiwan water resources planning are always used for solving long-term water supply problem. However extreme events have happened frequently under global climate change. The water supply suffers a severe challenge. The short-term shortage can\'t be ignored. Water utilities can take numerous actions to improve water availability or cope with shortages. Such as long-term investments to expand infrastructure, and short-term measures to flexibly transfer, ration, or curtail some uses, represent several different approaches, timings, and spatial scales for management. That makes the decision more complex and difficult. Hence, the study proposes a Stochastic Programming with Recourse Decision Model (SPRDM) to solving this puzzle. SPRDM is applied to decide the best strategies combination of Northern Taiwan under future demand (2021). The study identifies the best solutions to reach sustainable purpose for water resources management.
The development of a real-time flooding operation model in the Tseng-Wen Reservoir
(2014)
Chen, Yu-Wen
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Tsai, Jul-Pin
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Chang, Liang-Cheng
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Ho, Chih-Chao
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Chen, You-Cheng
Typhoon events occur frequently in Taiwan resulting in flood-related disasters. A well-operated reservoir can reduce the severity of a disaster. This study incorporates a genetic algorithm, a river hydraulic model, an artificial neural network and a simulation model of Tseng-Wen Reservoir to propose a real-time flooding operation model. The model includes two parts: an optimal flooding operation model (OFOM) and a reservoir inflow forecasting. Given an inflow condition, the OFOM is run based on the safety of the dam structure, reservoir flooding operation rule, and minimization of the downstream loss due to flood. A simple and robust model for reservoir inflow forecasting, which automatically chooses the most similar event from a typhoon event database as the future inflow, is developed. This study compares the model results with the real operations during Typhoons Sepat, Krosa, Kalmaegi, Fung-wong, Sinlaku, and Jangmi. This study compares the performances of the proposed model with the practical operation operated by the management center of Tseng-Wen Reservoir. The proposed model indicates shorter flooding duration in the downstream area. For example, the flood durations of the model output are 4 and 3 hours shorter during Typhoon Krosa and Sinlaku, respectively, than the practical operations.