Yen-Chang Chen - Academia.edu (original) (raw)
Papers by Yen-Chang Chen
Hydrological Processes, Jun 8, 2004
Discharge, especially during flood periods, is among the most important information necessary for... more Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Hydrology, Aug 1, 2002
The efficient method presented herein is based on the regularity of water flow in an open channel... more The efficient method presented herein is based on the regularity of water flow in an open channel, which is maintained by nature at a constant ratio of mean to maximum velocities at a channel section. This ratio is a function of a parameter of a probability distribution that is equivalent to velocity distribution in the physical space. The maximum velocity can be determined quickly by measuring only a few velocities from a single vertical axis. As well as the ratio, the location of the sampling vertical axis on which the maximum velocity occurs tends to remain invariant with time. The mean velocity in a section can be rapidly determined by estimating the product of the maximum velocity multiplied by the ratio. The crosssectional area of an open channel can be determined by the relation between gage height and area. Thus, the discharge in an open channel may be estimated as the product of mean velocity multiplied by the cross-sectional area. This efficient method can be used with any current meter to reduce the time and cost of discharge measurement in open channel flows under tidal effect. The available data of the Tanshui River downstream reach of which is in an estuarine area is used to illustrate the accuracy and reliability of the method. The results show that the simple but reliable method is capable of estimating discharge in tidal streams.
Journal of Hydraulic Engineering, 2000
Mathematical models have been developed that can completely describe the distribution of sediment... more Mathematical models have been developed that can completely describe the distribution of sediment concentration from the channel bed to the water surface. These models can be used to estimate the mean (depth-averaged) sediment concentration by a quick, point sampling in river engineering practice. The developed models are products of a combined application of the deterministic and probabilistic concepts. The complementary nature of the two concepts strengthens the methodology of describing the various features of sediment transport. The models incorporate a velocity distribution equation that corresponds to a probability distribution derived by maximizing the information entropy. The probability distribution is a compact description of the system at a channel section, and its resilience or stability explains the applicability of the developed models of velocity and sediment distributions in a wide range of flows, steady or unsteady.
Water resources engineering, 1998
Water
This study developed an efficient discharge measurement method that can be applied to estimate th... more This study developed an efficient discharge measurement method that can be applied to estimate the streamflow of natural streams and artificial channels. The conventional methods that apply current meters to measure discharge are costly, time-consuming, and labor-intensive. Owing to a shortage of observers in streamflow measurement and for the safety of hydrologists and with advances in measurement techniques, many have strongly suggested the use of non-contact methods when determining streamflow. The non-contact methods that use floats or surface velocity radar to determine the streamflow are becoming more and more popular especially during periods of high water. However, it is not easy to estimate the surface velocity coefficient of each vertical directly for determining the mean velocity in each subsection. As the relationship between the mean surface velocity and mean velocity of a stream cross-section is constant, an efficient and accurate non-contact method of streamflow measu...
Water resources engineering, 1998
For many years, hot spring spas have been a major tourist attraction in Taiwan. During peak touri... more For many years, hot spring spas have been a major tourist attraction in Taiwan. During peak tourist seasons a very large amount of bathing water is usually discharged into streams without treatment, which could result in the degradation of the receiving water quality. The Nan-shih Creek, which supplies drinking water to the Taipei Metropolitan area residents, was chosen for a case study. To investigate whether the untreated bathing water discharge of hot spring spas would adversely impact the Nan-shih Creek water quality, the stream model QUAL2E was used to simulate the impact. It was found that when the stream flow was close to the design low flow, (Q 75 is used in Taiwan), the NH 3 -N and coliform levels in the Nan-shih Creek would exceed river water quality standards as a result of the hot spring spa bathing water discharge. QUAL2E simulates both the concentrations of NH 3 -N and coliform in the conditions of stream flow with and without hot spring bathing water. It indicates if ...
Hydrological Processes, 2004
Discharge, especially during flood periods, is among the most important information necessary for... more Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Hydraulic Research, Nov 1, 2003
... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential dist... more ... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential distribution of u/umM that has a single parameter M. Chiu (1988, 1989) derived (3) by maximizing the Shannon's probability-based information entropy (Shannon. 1948). ...
Terrestrial, Atmospheric and Oceanic Sciences, 2020
For this study, dust storm data was collected on 24-25 March, 2012. This dust storm impacted the ... more For this study, dust storm data was collected on 24-25 March, 2012. This dust storm impacted the northern area of Taiwan for about two days, so our study was confined to the northern air quality region of Taiwan using indicator kriging for assessing the probability of exceeding the threhold concentration of PM 2.5. Results showed that the highest levels of dust storm pollution in the study area were in the Zhongzheng District of Taipei City, with a concentration of 39.86 μg m-3. The lowest levels were 21.88 μg m-3 , in Xinzhuang District, New Taipei City. Among the four administrative regions, variation was greatest in Taipei City, with concentrations between 22.74 and 39.86 μg m-3 , and lowest in Keelung City, with concentrations between 23.97 and 27.56 μg m-3. We categorized pollution concentrations with probabilities greater than 0.7 into three categories to represent health risk hazards. Eighty-seven percent of areas were low risk, with PM 2.5 concentrations above 25 μg m-3. Areas with PM 2.5 concentrations greater than 30 μg m-3 were considered moderate risk areas, and comprised 1.2% of all area; this category appeared in the Zhongshan, Songshan, Datong, and Daan Districts of Taipei City and the Zhongli District of Taoyuan City. Concentrations greater than 35 μg m-3 , labeled high risk areas, accounted for only 0.4% and were concentrated in the Zhongshan, Songshan, and Zhongli Districts of Taipei City. The methods used in this study and its results can be key references for future early warning and prevention of dust pollution by relevant authorities.
Paddy and Water Environment, 2011
Designing storm hyetographs is the essential element of hydrologic modeling analysis and storm wa... more Designing storm hyetographs is the essential element of hydrologic modeling analysis and storm water drainage design. In order to reasonably use storm hyetograph design in an un-gauged area, a regional representative hyetograph from an alternative and uniform area must be found. A new approach is proposed in this study to select a regional design storm hyetograph using principal component analysis (PCA) and analytic hierarchy process (AHP). The proposed approach combines both PCA and cluster analysis techniques. Furthermore, the AHP method is also used to establish the regional design hyetograph. A case study applied in the area of northern Taiwan shows that our method can successfully categorize the area into three homogenous zones. A representative regional hyetograph can be obtained by selecting the largest priority vector or by the weighted average of rain gauges in each zone.
Entropy, 2014
Because of high variation in mountainous areas, rainfall data at different spatiotemporal scales ... more Because of high variation in mountainous areas, rainfall data at different spatiotemporal scales may yield potential uncertainty for network design. However, few studies focus on the scaling effect on both the spatial and the temporal scale. By calculating the maximum joint entropy of hourly typhoon events, monthly, six dry and wet months and annual rainfall between 1992 and 2012 for 1-, 3-, and 5-km grids, the relocated candidate rain gauges in the National Taiwan University Experimental Forest of Central Taiwan are prioritized. The results show: (1) the network exhibits different locations for first prioritized candidate rain gauges for different spatiotemporal scales; (2) the effect of spatial scales is insignificant compared to temporal scales; and (3) a smaller number and a lower percentage of required stations (PRS) reach stable joint entropy for a long duration at finer spatial scale. Prioritized candidate rain gauges provide key reference points for adjusting the network to capture more accurate information and minimize redundancy.
World Environmental and Water Resource Congress 2006, 2006
Journal of Hydroinformatics, 2010
This paper documents a real-time storm sewer simulation system (RTS4) in conjunction with a Storm... more This paper documents a real-time storm sewer simulation system (RTS4) in conjunction with a Storm Water Management Model (SWMM) based on a pattern-oriented approach. The RTS4 is initiated by system analysis ascertaining functional requirements, which is sequentially followed by conceptual model, pattern languages, concrete pattern-based design, implementations and applications. The proposed conceptual model helps sketch out a core software skeleton in relation to prior system requirement analysis. Of the proposed pattern languages, each can be regarded as a ‘building block’ on which the concrete pattern-based design is built. Finally, the RTS4 is implemented by following the proposed pattern-oriented design. The applicability of RTS4 is demonstrated with respect to storm sewer simulation and real-time operations. The results of the simulation show that the proposed pattern-oriented approach offers a promising basis for software system developments such as RTS4.
Journal of Hydraulic Research, 2003
... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential dist... more ... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential distribution of u/umM that has a single parameter M. Chiu (1988, 1989) derived (3) by maximizing the Shannon's probability-based information entropy (Shannon. 1948). ...
Environmental Modelling & Software, 2006
This paper presents an approach that integrates a legacy component into a software system for sto... more This paper presents an approach that integrates a legacy component into a software system for storm sewer simulation. The legacy component employed here is the Storm Water Management Model (SWMM). The Extended Transport (EXTRAN) block of the SWMM that applies the finite difference method (FDM) with explicit numerical schemes, solving the de Saint-Venant equations, is used to route the storm sewer flow. A storm sewer simulation system, named S4, that integrates SWMM-EXTRAN and implements a visualization model, has been developed to demonstrate the proposed approach. The approach makes use of the multithread technology to alternate the execution between SWMM-EXTRAN for flow simulation on one thread and the program controller that updates simulation state variables and displays the computed temporal water-stages at the junctions on the other thread at every time step of the FDM process. Two test examples are used to verify and demonstrate the feasibility of the proposed approach. The results show that the multi-thread technology is applied successfully for integrating legacy components, such as SWMM-EXTRAN, into a software system (in this case, S4). In addition, the proposed approach is generally applicable for integrating legacy models or components developed using FDM with explicit numerical schemes.
Hydrological Processes, 2013
This study presents a new method to measure stream cross section without having contact with wate... more This study presents a new method to measure stream cross section without having contact with water. Compared with conventional measurement methods which apply instruments such as sounding weight, ground penetration radar (GPR), used in this study, is a non-contact measurement method. This non-contact measurement method can reduce the risk to hydrologists when they are conducting measurements, particularly in high flow period. However, the original signals obtained by using GPR are very complex, different from studies in the past where the measured data were mostly interpreted by experts with special skill or knowledge of GPR so that the results obtained were less objective. This study employs Hilbert-Huang transform (HHT) to process GPR signals which are difficult to interpret by hydrologists. HHT is a newly developed signal processing method that can not only process the nonlinear and non-stationary complex signals, but also maintain the physical significance of the signal itself. Using GPR with HHT, this study establishes a non-contact stream cross-section measurement method with the ability to measure stream cross-sectional areas precisely and quickly. Also, in comparison with the conventional method, no significant difference in results is found to exist between the two methods, but the new method can considerably reduce risk, measurement time, and manpower. It is proven that the non-contact method combining GPR with HHT is applicable to quickly and accurately measure stream cross section.
The method for measuring flood discharge of mountain rivers is described first. Then the data col... more The method for measuring flood discharge of mountain rivers is described first. Then the data collected in the Nanshih River at the Lengsheng Bridge is used to show that the proposed method can be successfully applied to measure flood discharge. I will rewrite the abstract, introduction, and conclusions to more carefully and precisely claim the method using for measuring discharge of mountain rivers.
Hydrological Processes, Jun 8, 2004
Discharge, especially during flood periods, is among the most important information necessary for... more Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Hydrology, Aug 1, 2002
The efficient method presented herein is based on the regularity of water flow in an open channel... more The efficient method presented herein is based on the regularity of water flow in an open channel, which is maintained by nature at a constant ratio of mean to maximum velocities at a channel section. This ratio is a function of a parameter of a probability distribution that is equivalent to velocity distribution in the physical space. The maximum velocity can be determined quickly by measuring only a few velocities from a single vertical axis. As well as the ratio, the location of the sampling vertical axis on which the maximum velocity occurs tends to remain invariant with time. The mean velocity in a section can be rapidly determined by estimating the product of the maximum velocity multiplied by the ratio. The crosssectional area of an open channel can be determined by the relation between gage height and area. Thus, the discharge in an open channel may be estimated as the product of mean velocity multiplied by the cross-sectional area. This efficient method can be used with any current meter to reduce the time and cost of discharge measurement in open channel flows under tidal effect. The available data of the Tanshui River downstream reach of which is in an estuarine area is used to illustrate the accuracy and reliability of the method. The results show that the simple but reliable method is capable of estimating discharge in tidal streams.
Journal of Hydraulic Engineering, 2000
Mathematical models have been developed that can completely describe the distribution of sediment... more Mathematical models have been developed that can completely describe the distribution of sediment concentration from the channel bed to the water surface. These models can be used to estimate the mean (depth-averaged) sediment concentration by a quick, point sampling in river engineering practice. The developed models are products of a combined application of the deterministic and probabilistic concepts. The complementary nature of the two concepts strengthens the methodology of describing the various features of sediment transport. The models incorporate a velocity distribution equation that corresponds to a probability distribution derived by maximizing the information entropy. The probability distribution is a compact description of the system at a channel section, and its resilience or stability explains the applicability of the developed models of velocity and sediment distributions in a wide range of flows, steady or unsteady.
Water resources engineering, 1998
Water
This study developed an efficient discharge measurement method that can be applied to estimate th... more This study developed an efficient discharge measurement method that can be applied to estimate the streamflow of natural streams and artificial channels. The conventional methods that apply current meters to measure discharge are costly, time-consuming, and labor-intensive. Owing to a shortage of observers in streamflow measurement and for the safety of hydrologists and with advances in measurement techniques, many have strongly suggested the use of non-contact methods when determining streamflow. The non-contact methods that use floats or surface velocity radar to determine the streamflow are becoming more and more popular especially during periods of high water. However, it is not easy to estimate the surface velocity coefficient of each vertical directly for determining the mean velocity in each subsection. As the relationship between the mean surface velocity and mean velocity of a stream cross-section is constant, an efficient and accurate non-contact method of streamflow measu...
Water resources engineering, 1998
For many years, hot spring spas have been a major tourist attraction in Taiwan. During peak touri... more For many years, hot spring spas have been a major tourist attraction in Taiwan. During peak tourist seasons a very large amount of bathing water is usually discharged into streams without treatment, which could result in the degradation of the receiving water quality. The Nan-shih Creek, which supplies drinking water to the Taipei Metropolitan area residents, was chosen for a case study. To investigate whether the untreated bathing water discharge of hot spring spas would adversely impact the Nan-shih Creek water quality, the stream model QUAL2E was used to simulate the impact. It was found that when the stream flow was close to the design low flow, (Q 75 is used in Taiwan), the NH 3 -N and coliform levels in the Nan-shih Creek would exceed river water quality standards as a result of the hot spring spa bathing water discharge. QUAL2E simulates both the concentrations of NH 3 -N and coliform in the conditions of stream flow with and without hot spring bathing water. It indicates if ...
Hydrological Processes, 2004
Discharge, especially during flood periods, is among the most important information necessary for... more Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Hydraulic Research, Nov 1, 2003
... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential dist... more ... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential distribution of u/umM that has a single parameter M. Chiu (1988, 1989) derived (3) by maximizing the Shannon's probability-based information entropy (Shannon. 1948). ...
Terrestrial, Atmospheric and Oceanic Sciences, 2020
For this study, dust storm data was collected on 24-25 March, 2012. This dust storm impacted the ... more For this study, dust storm data was collected on 24-25 March, 2012. This dust storm impacted the northern area of Taiwan for about two days, so our study was confined to the northern air quality region of Taiwan using indicator kriging for assessing the probability of exceeding the threhold concentration of PM 2.5. Results showed that the highest levels of dust storm pollution in the study area were in the Zhongzheng District of Taipei City, with a concentration of 39.86 μg m-3. The lowest levels were 21.88 μg m-3 , in Xinzhuang District, New Taipei City. Among the four administrative regions, variation was greatest in Taipei City, with concentrations between 22.74 and 39.86 μg m-3 , and lowest in Keelung City, with concentrations between 23.97 and 27.56 μg m-3. We categorized pollution concentrations with probabilities greater than 0.7 into three categories to represent health risk hazards. Eighty-seven percent of areas were low risk, with PM 2.5 concentrations above 25 μg m-3. Areas with PM 2.5 concentrations greater than 30 μg m-3 were considered moderate risk areas, and comprised 1.2% of all area; this category appeared in the Zhongshan, Songshan, Datong, and Daan Districts of Taipei City and the Zhongli District of Taoyuan City. Concentrations greater than 35 μg m-3 , labeled high risk areas, accounted for only 0.4% and were concentrated in the Zhongshan, Songshan, and Zhongli Districts of Taipei City. The methods used in this study and its results can be key references for future early warning and prevention of dust pollution by relevant authorities.
Paddy and Water Environment, 2011
Designing storm hyetographs is the essential element of hydrologic modeling analysis and storm wa... more Designing storm hyetographs is the essential element of hydrologic modeling analysis and storm water drainage design. In order to reasonably use storm hyetograph design in an un-gauged area, a regional representative hyetograph from an alternative and uniform area must be found. A new approach is proposed in this study to select a regional design storm hyetograph using principal component analysis (PCA) and analytic hierarchy process (AHP). The proposed approach combines both PCA and cluster analysis techniques. Furthermore, the AHP method is also used to establish the regional design hyetograph. A case study applied in the area of northern Taiwan shows that our method can successfully categorize the area into three homogenous zones. A representative regional hyetograph can be obtained by selecting the largest priority vector or by the weighted average of rain gauges in each zone.
Entropy, 2014
Because of high variation in mountainous areas, rainfall data at different spatiotemporal scales ... more Because of high variation in mountainous areas, rainfall data at different spatiotemporal scales may yield potential uncertainty for network design. However, few studies focus on the scaling effect on both the spatial and the temporal scale. By calculating the maximum joint entropy of hourly typhoon events, monthly, six dry and wet months and annual rainfall between 1992 and 2012 for 1-, 3-, and 5-km grids, the relocated candidate rain gauges in the National Taiwan University Experimental Forest of Central Taiwan are prioritized. The results show: (1) the network exhibits different locations for first prioritized candidate rain gauges for different spatiotemporal scales; (2) the effect of spatial scales is insignificant compared to temporal scales; and (3) a smaller number and a lower percentage of required stations (PRS) reach stable joint entropy for a long duration at finer spatial scale. Prioritized candidate rain gauges provide key reference points for adjusting the network to capture more accurate information and minimize redundancy.
World Environmental and Water Resource Congress 2006, 2006
Journal of Hydroinformatics, 2010
This paper documents a real-time storm sewer simulation system (RTS4) in conjunction with a Storm... more This paper documents a real-time storm sewer simulation system (RTS4) in conjunction with a Storm Water Management Model (SWMM) based on a pattern-oriented approach. The RTS4 is initiated by system analysis ascertaining functional requirements, which is sequentially followed by conceptual model, pattern languages, concrete pattern-based design, implementations and applications. The proposed conceptual model helps sketch out a core software skeleton in relation to prior system requirement analysis. Of the proposed pattern languages, each can be regarded as a ‘building block’ on which the concrete pattern-based design is built. Finally, the RTS4 is implemented by following the proposed pattern-oriented design. The applicability of RTS4 is demonstrated with respect to storm sewer simulation and real-time operations. The results of the simulation show that the proposed pattern-oriented approach offers a promising basis for software system developments such as RTS4.
Journal of Hydraulic Research, 2003
... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential dist... more ... by (u) = («/«max) where .( u \_ M / u \ \Wmax/ eM - 1 V Unm) which is an exponential distribution of u/umM that has a single parameter M. Chiu (1988, 1989) derived (3) by maximizing the Shannon's probability-based information entropy (Shannon. 1948). ...
Environmental Modelling & Software, 2006
This paper presents an approach that integrates a legacy component into a software system for sto... more This paper presents an approach that integrates a legacy component into a software system for storm sewer simulation. The legacy component employed here is the Storm Water Management Model (SWMM). The Extended Transport (EXTRAN) block of the SWMM that applies the finite difference method (FDM) with explicit numerical schemes, solving the de Saint-Venant equations, is used to route the storm sewer flow. A storm sewer simulation system, named S4, that integrates SWMM-EXTRAN and implements a visualization model, has been developed to demonstrate the proposed approach. The approach makes use of the multithread technology to alternate the execution between SWMM-EXTRAN for flow simulation on one thread and the program controller that updates simulation state variables and displays the computed temporal water-stages at the junctions on the other thread at every time step of the FDM process. Two test examples are used to verify and demonstrate the feasibility of the proposed approach. The results show that the multi-thread technology is applied successfully for integrating legacy components, such as SWMM-EXTRAN, into a software system (in this case, S4). In addition, the proposed approach is generally applicable for integrating legacy models or components developed using FDM with explicit numerical schemes.
Hydrological Processes, 2013
This study presents a new method to measure stream cross section without having contact with wate... more This study presents a new method to measure stream cross section without having contact with water. Compared with conventional measurement methods which apply instruments such as sounding weight, ground penetration radar (GPR), used in this study, is a non-contact measurement method. This non-contact measurement method can reduce the risk to hydrologists when they are conducting measurements, particularly in high flow period. However, the original signals obtained by using GPR are very complex, different from studies in the past where the measured data were mostly interpreted by experts with special skill or knowledge of GPR so that the results obtained were less objective. This study employs Hilbert-Huang transform (HHT) to process GPR signals which are difficult to interpret by hydrologists. HHT is a newly developed signal processing method that can not only process the nonlinear and non-stationary complex signals, but also maintain the physical significance of the signal itself. Using GPR with HHT, this study establishes a non-contact stream cross-section measurement method with the ability to measure stream cross-sectional areas precisely and quickly. Also, in comparison with the conventional method, no significant difference in results is found to exist between the two methods, but the new method can considerably reduce risk, measurement time, and manpower. It is proven that the non-contact method combining GPR with HHT is applicable to quickly and accurately measure stream cross section.
The method for measuring flood discharge of mountain rivers is described first. Then the data col... more The method for measuring flood discharge of mountain rivers is described first. Then the data collected in the Nanshih River at the Lengsheng Bridge is used to show that the proposed method can be successfully applied to measure flood discharge. I will rewrite the abstract, introduction, and conclusions to more carefully and precisely claim the method using for measuring discharge of mountain rivers.