Ray-Shyan Wu

Ray-Shyan Wu
National Central University | NCU · Department of Civil Engineering

PhD

About

78
Publications
9,868
Reads
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491
Citations
Citations since 2017
34 Research Items
284 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Additional affiliations
September 1990 - present
National Central University
Position
  • Professor (Full)
August 1990 - present
National Central University
Position
  • Professor (Full)
Description
  • in water resources
Education
August 1984 - July 1990
Cornell University
Field of study
  • Biological and Environmental Engineering

Publications

Publications (78)
Article
Full-text available
The trend analysis approach is used to estimate changing climate and its impact on the environment, agriculture and water resources. Innovative polygonal trend analyses are qualitative methods applied to detect changes in the environment. In this study, the Innovative Trend Pivot Analysis Method (ITPAM) and Trend Polygon Star Concept Method were ap...
Article
Full-text available
This study represents the first report of the innovative use of seven types of first-order univariate grey model, abbreviated as GM (1, 1) model, for comprehensive groundwater quality prediction in the Chishan basin of Taiwan in which some districts exhibit a certain level of risk for flood and drought. The results indicated that GM (1, 1) model wa...
Article
Full-text available
The reliability of weather radar data in real-time flood forecasting and early warning system remains ambivalent due to high uncertainty in Quantitative Precipitation Forecasts (QPF). In this study, a methodology is presented with the objective to improve the flood forecasting results with the application of radar rainfall calculated in three diffe...
Article
Full-text available
Study region Four districts (Meinong, Qishan, Dashu, and Daliao) of Kaohsiung city, Southern Taiwan Study focus The understanding of aquifer recharge in terms of water table response to rainfall is of critical importance to groundwater systems management and various endeavors have been made to estimate the amount of recharge using rainfall data. T...
Article
Full-text available
The investigations of groundwater hydrograph reasonably reflect the aquifer response to recharge–discharge phenomenon and its characteristics. A better understanding of aquifer characteristics such as regional aquifer classification, recharge and discharge patterns, aquifer geology and flow patterns are the surface indicators that may be more effec...
Article
Full-text available
Reliable hourly flood forecasting using weather radar rainfall data for early warning system is essential for reducing natural disaster risk during extreme typhoon events. This study proposed a novel approach integrated with physics-based WASH123D and HEC-HMS models to forecast 1 h ahead flood level in the Fengshan Creek basin, northern Taiwan. The...
Article
Full-text available
Hydrologic modeling is a commonly used tool to understand the rainfallerunoff processes of gauged and ungauged catchments for proper quantitative estimation of water resources availability. In the present study, an attempt is made to simulate surface runoff using a physically based semi-distributed hydrological (HEC-HMS) model for four local-scale...
Preprint
Samarinda City is one of the most attractive cities in Borneo Island (Indonesia) and also as a capital city of EastBorneo Province. The expansion of urban areas becomes essential due to rapid population and housing demand. Base on the statistical report, the annual population growth rate is 0.018% from the year 2016-2017 with a total population of...
Preprint
Full-text available
Hydraulic conductivity is the key and one of the most uncertain parameters in groundwater modeling. The grid based numerical simulation requires spatial distribution of sampled hydraulic conductivity at un-sampled locations in the study area. This spatial interpolation has been routinely performed using variogram based models (two-point geostatisti...
Preprint
Samarinda’s flooding issue is threatening future city development. As the most populated city in Kalimantan, Samarinda (the municipality of East Borneo) plays a role-model in disaster management for a neighboring city. This paper introduces current flood disaster handling in this city. History of disaster management in Indonesia is started from the...
Article
Full-text available
Streamflow recession analysis is widely used for estimating catchment-scale hydrogeological parameters in gauged catchments because of its low cost, ease of use, and efficiency in terms of results. In this work, however, the same methodology was applied to ungauged creek catchments, where low recession flows were simulated using physically based, s...
Article
Full-text available
This study evaluates the spatiotemporal rainfall variability over the semimountainous Soan River Basin (SRB) of sub-Himalayan Pothwar region, Pakistan. The temporal rainfall trend analysis of sixteen rain gauges was performed on annual basis with long-term (1981–2016) data. The results depicted that there is substantial year-to-year and season-to-s...
Article
Full-text available
This study evaluated the effectiveness of soil and water conservation structures for soil erosion control by applying a semi-distributed Soil and Water Assessment Tool (SWAT) model in various small watersheds of the Chakwal and Attock districts of Pothwar, Pakistan. The validated model without soil conservation structures was applied to various ung...
Conference Paper
Full-text available
This study devises a practical solution to mitigate urban inundation and artificial recharge of groundwater using recharge wells which is the most viable surface runoff RWH technique in urban areas. Rainwater Harvesting Pilot Project at Gaddafi Stadium Lahore was established to deal with urban flooding, artificial recharge of groundwater and to avo...
Article
Full-text available
This study devised a practical solution to mitigate urban inundation and artificial recharge of groundwater using recharge wells which is the most viable surface runoff rainwater harvesting (RWH) technique in urban areas. The Rainwater Harvesting Pilot Project at Gaddafi Stadium Lahore was established to deal with urban flooding, artificial recharg...
Conference Paper
Full-text available
This study devises a practical solution to mitigate urban inundation and artificial recharge of groundwater using recharge wells which is the most viable surface runoff RWH technique in urban areas. Rainwater Harvesting Pilot Project at Gaddafi Stadium Lahore was established to deal with urban flooding, artificial recharge of groundwater and to avo...
Preprint
Full-text available
This study mainly focuses on Lahore city, the second-largest urban hub of Pakistan. The city area is facing two severe problems, one is the rapid decline in groundwater level due to extensive extraction of groundwater and other is regular flooding in city area during monsoon season. Over the last two decades, and more importantly since the mid of...
Conference Paper
Full-text available
Samarinda’s flooding issue is threatening future city development. As the most populated city in Kalimantan, Samarinda (the municipality of East Borneo) plays a role-model in disaster management for a neighboring city. This paper introduces current flood disaster handling in this city. History of disaster management in Indonesia is started from the...
Conference Paper
Full-text available
Hydraulic conductivity is the key and one of the most uncertain parameters in groundwater modeling. The grid based numerical simulation require spatial distribution of sampled hydraulic conductivity at un-sampled locations in the study area. This spatial interpolation has been routinely performed using variogram based models (two-point geostatistic...
Conference Paper
Full-text available
Samarinda City is one of the most attractive city in Borneo Island (Indonesia) and also as a capital city of East Borneo Province. The expansion of urban area becomes essential due to rapid population and housing demand. Base on the statistical report, the annual population growth rate is 0.018% from the year 2016-2017 with a total population of 84...
Article
Full-text available
Uncertainty is inherent in modeling studies. However, the quantification of uncertainties associated with a model is a challenging task. Furthermore, snowmelt estimation is a crucial part of the Soil and Water Assessment Tool (SWAT) model in watersheds where spring runoff is strongly affected by melting snow. The SWAT model for the snow dependent K...
Article
Full-text available
This research was undertaken for the evaluation of soil erosion using the semi-distributed basin scale SWAT model for four subcatchments of the Dhrabi River Catchment (DRC), which is located in the Pothwar Plateau region. Two subcatchments (catchment-25 and-31) are characterized by gullies while the other two (catchment-27 and-32) are managed with...
Article
Full-text available
The Guatemala’s rural population have limited resources, high vulnerability to climate change, traditional agriculture practices and adversely affected by water scarcity. These problems engender the need for further economic development and imposed pressure on the existing water resources. In response, Rain Water Harvest (RWH) is the measure as an...
Article
Full-text available
The study uses weather generation models to generate future daily rainfall and temperature, and incorporates a land coverage model to simulate future land use changes. These future scenarios are then simulated by a rainfall runoff model to study their impacts on basin discharge, river, and groundwater levels. The Fengshan Creek basin in northern Ta...
Conference Paper
Full-text available
Evaporation is the key controlling factor of hydrological cycle. The global temperature is increasing and the expected results on evaporation should be positive. However, the pan evaporation is decreasing all over the world in last 50 years. This indicated the existence of pan evaporation paradox. Keeping in view the global issue, the annual and se...
Conference Paper
Full-text available
Flood issue in Samarinda almost surrounding every year, especially in the rainy season (October-April). Its issue depends on the several factors such as drainage condition, topographical area and also the problems of Karang Mumus river. This paper focused on the river problem. This river has decreasing capacity caused by constriction. Its affected...
Conference Paper
Full-text available
Soil erosion by water is one of the most important land degradation processes in the Pothwar region of Pakistan. Intensive rainstorms in the monsoon season generate sharp peak runoffs which, combined with steep topography and low vegetation, cause gully expansion as a result of extensive soil erosion. This study was conducted in the Dhrabi watershe...
Article
Full-text available
Taiwan average annual rainfall is approximately 2500 mm. In particular, 80% of the rainfall occurs in summer, and most of the heavy rainfall is caused by typhoons. The situation is worsening as climate change results in uneven rainfall, both in spatial and temporal terms. Moreover, climate change has resulted the variations in the seasonal rainfall...
Conference Paper
Full-text available
Flooding issues in Samarinda have high depending on the capacity of Karang Mumus river. Considering the ability of Karang Mumus river to drain off flood discharge, there wore evidence that the constriction of River will drive to flooding issues, especially in rainy/wet season (October-April). The constriction of river happens because many people bu...
Preprint
Flooding issues in Samarinda have high depending on the capacity of Karang Mumus river. Considering the ability of Karang Mumus river to drain off flood discharge, there wore evidence that the constriction of River will drive to flooding issues, especially in rainy/wet season (October-April). The constriction of river happens because many people bu...
Conference Paper
Full-text available
Soil erosion is one of the most important land degradation issues in the rainfed areas of Pakistan. A study was undertaken in micro watersheds of District Chakwal Pakistan to control the soil erosion using soil conservation loose stone structures. The Soil and Water Assessment Tool (SWAT) model was mimicked to find out the effect of loose stone str...
Article
Full-text available
This study evaluated parameters of soil erosion and optimization of micro watersheds by applying a semidistributed basin-scale Soil and Water Assessment Tool (SWAT) model in various small watersheds of the Chakwal and Attock districts of Pothwar, Pakistan. The model was calibrated and validated on a daily basis for a small catchment (Catchment-25)...
Preprint
Full-text available
This paper proposes a method to utilize weather and land cover models to generate future environmental scenarios, and presents the watershed models to simulate the hydrological impact on watershed-scale hydrology. The Weather Generator model and General Circulation Model were applied to produce rainfall and local temperature under different climate...
Chapter
A correlational analysis of particulate matter (PM) characteristics and land use patterns at different river basins of Taiwan was carried out in this study. 10 river basins with more complete data were selected, including Zhoushui River, Beigang River, Jishui River, Zengwen River, Yanshui River, Agongdian River, Dajia River, Daan River, Sizhong Riv...
Conference Paper
During the past few decades in Fengshan creek basin of northern Taiwan, land excessive reclamations were conducted and more and more golf courses have been built on the hillside. As rainy and typhoon season comes, heavy rainfall induced flash floods and surface inundations usually brings significant damages to local populations and destroyed their...
Chapter
In this study, social security adds, control, and management for flood in Taiwan under extreme climate were studied between 1994 and 2013. First, the laws related to disasters prevention and social add were surveyed, including the Disaster Prevention and Protection Act (DPPA) and Public Assistance Act (PAA). Second, the times of flood and amount of...
Article
Full-text available
This study involved developing a natural disaster risk assessment framework based on the consideration of three phases: a pre-disaster phase, disaster impact phase, and post-disaster recovery phase. The exposure of natural disasters exhibits unique characteristics. The interactions of numerous factors should be considered in risk assessment as well...
Article
The agricultural water requirement was different from year to year depending on the weather scenarios, temperature and rainfall mainly in the cultivation period. The estimating of the agricultural water requirement was depending on the historical meteorological data for a long time. In this study, we estimated the agricultural water requirement wit...
Article
The upstream Lesti watershed is one of the major watersheds of East Java in Indonesia, covering about 38093 hectares. Although there are enough water resources to meet current demands in the basin, many challenges including high spatial and temporal variability in precipitation from year to year exist. It is essential to understand how the climatic...
Article
Water is one of the most valuable resources on earth with the advent of climate change. It stands to be severely impacted as compared to other resources. Small Island Developing States (SIDS) such as St. Vincent and the Grenadines are more vulnerable to these impacts as they depend heavily on surface water for much of their consumption. Coupled wit...
Article
This study modified the generalized watershed loading functions (GWLF) model, and applied the modified model to simulate the water flow of the catchment area of the Lan-Yang River, by entering the current status of land use, hydrological data, and meteorological data into the model. This modified model took soil resistance into consideration when c...
Article
Due to the special topography, the rainfall in Taiwan is quite uneven both in time and space distribution. Partially due to the impact of climate change in recent years, the water supply with a high degree of uncertainty leading to the subject of intense competition for water. Taiwan moves from agricultural economy to the development of industrial...
Article
In this study, seven types of first-order and one-variable grey differential equation model (abbreviated as GM (1, 1) model) were used to predict the hardness of four groundwater monitoring stations in Kaohsiung City of Taiwan. The mean absolute percentage error (MAPE) was used to evaluate the predicting performance. The results indicated the minim...
Article
In the recent years, the rainfall intensity rises sharply in Taiwan due to global climate variations, and it may result in the situations such as increased flooding and droughts, the reservoir storage volume is insufficient, and it causes the management and the distribution of water resources more and more difficult in the future. This study discus...
Conference Paper
The pond irrigation system, which is an example of the great wisdom of our ancestors in the early twentieth century, increases the effective rainfall by using geographic features to overcome hydrologic disadvantages. The concept of the pond irrigation system is to reserve excess runoff in farm ponds as if in small reservoirs and then to supply wate...
Article
Based on the HEC-RAS and River 2D modes, and taking 5% change rate of weighted usable area (WUA) as the threshold to define the spur dike- affected area of target fish species Acrossocheilus paradoxus in Fazi River in Taiwan, this paper studied the affected area of the fish habitat by spur dike, and, in combining with the references about the insta...
Article
Although the amount of spring rain is only 10% of total rainfall in Taiwan, it plays an important role of water resource allocation during drought periods. Therefore, increase the rainfall forecast ability will help the combination of surface water and groundwater usage during drought period, it will also help early warning and policy decision. Thi...
Article
An electro‐kinetic method which combined effects of electrophoresis, electro‐osmosis, electrolysis, and ion exchange, was evaluated for the removal of crude oil from a contaminated soil. A field test was designed to evaluate the removal process and to measure physical and chemical changes which occurred in the soil as a result of electro‐kinetic tr...
Article
In recent years, the domestic and industrial water demand have got uptrend gradually because of social and economical environment change and the promotion of living standard. Some of the water has always been transferred from agricultural sector to the domestic and industrial sector when facing deficits. Therefore, how to find reliable alternative...
Article
The amount of photosynthetically active radiation (PAR) in the water column is of fundamental importance in determining the growth of aquatic plant and aquatic primary production. Light attenuation in aquatic ecosystems has important ecological implication and water quality applications. In the present study, the light attenuation through the water...
Article
Full-text available
Some countries, including Taiwan, have adopted strategic environmental assessment (SEA) to assess and modify proposed policies, plans, and programs (PPPs) in the planning phase for pursuing sustainable development. However, there were only some sketchy steps focusing on policy assessment in the system of Taiwan. This study aims to develop a methodo...
Article
This study used a two-dimensional diffusion hydrodynamic model for the simulation of extreme flood events that occurred in the Shihmen reservoir watershed from 1989 to 2001. The alternating direction explicit scheme (ADE) with various horizontal spacings from 120 to 240m at an incremental interval of 40m was conducted for flood simulations. Spatial...
Article
This study examines a physical based distributed-parameter model combining surface runoff and ground water flow. Surface runoff is composed of both overland flow and river flow components, and the ground water module considers the unsaturated zone and saturated zone in an unconfined aquifer system. Previous works of surface flow module development...
Article
The assessment of river ecology is an integral part of river planning and management today. In any project, the simulation and quantification of river habitat and ecology is as important as the simulation of the hydrodynamics of the river. Currently in Taiwan, the use of one-dimensional models, such as Phabsim and Rhabsim, are widespread in the eva...
Article
In this study, we examine a physical raster-based distributed-parameter flood simulation model combining one-dimensional (1D) channel flow and two-dimensional (2D) overland flow. Continuity equations based on the water budget concept and momentum equations based on Manning’s formula are included. The Shihmen reservoir watershed, situated in norther...
Article
Precipitation data is generally collected from rain gauge stations. However, each measurement represents only the amount of rainfall at that particular spot, not precipitation in the surrounding area. Radar approaches are considered to offer a good spatial description of precipitation, but hardly predict precipitation quantities with acceptable acc...
Article
Full-text available
Water scarcity is a characteristic of the small coral atolls of Kiribati. The diminutive size of Kiribati means that development and freshwater resources are closely related and interlinked. Water resource management therefore seeks to rationalize the use of island resources with the goals of sustainable development. Rainwater harvesting, one of th...
Conference Paper
The purpose of this study is to evaluate the applicability of man-made ponds on assisting regional water resources management. The domain of interest is the water supply district of the Shihmen Reservoir, especially the water straitened Taoyuan area in northern Taiwan. To overcome the shortage of irrigation water in the past, numerous man-made pond...
Article
Based on the measured data, including total phosphorus, chlorophyll a, and Secchi disk depth, the Shihmen Reservoir in the state of mesotrophic to eutrophic. A two-dimensional, laterally averaged, finite-difference hydrodynamic, and water quality model was applied to simulate water quality conditions in the reservoir to determine appropriate strate...
Article
Typhoon Nari struck Taiwan on 16 September 2001, taking 92 lives. Analysis reveals that the storm's heavy rains were due to warmer ocean temperatures, Nari's unique track and slow-moving speed, and the terrain of Taiwan. Analysis further suggests that the heavy rains in Nari contained many small raindrops. The typhoon rains overwhelmed existing flo...
Article
Rice production in Taiwan is likely to decrease because of two major threats: an increase in the industrial demand on water resources and cheaper imported rice resulting from the free trade policy which will be enforced when Taiwan joins the World Trade Organization. A shrinkage in rice paddy acreage raises environmental concerns, especially in rel...
Article
The concept of driving force-state-response (DSR) framework was used to identify and develop the assessment model of water-land environment carrying capacity (WLECC) for a river basin. The river basin water-land management (RBWLM) decision support system was developed, based on the assessment model of WLECC, as a decision making tool. The Chung-Kan...
Article
Many optimization models to determine cost-effectiveness and obtain the least-cost system designs for water distribution networks have been developed. An algorithm used for solving an optimization model, such as the branch-and-bound or enumeration method, has deficiencies that may include efficiency problems and local optimal solution problems. A h...
Article
In considering of sustainable development, the decision-making of a river basin water management problem is very complicated and challenging. In this study, an effective and practical decision making theory and procedure was developed for river basin water management problems. Based on the theory and procedure, a useful and user friendly river basi...
Article
Many optimization models to determine cost-effectiveness and obtain the least-cost system designs for water distribution networks have been developed. An algorithm used for solving an optimization model, such as the branch-and-bound or enumeration method, has deficiencies that may include efficiency problems and local optimal solution problems. A h...
Article
This paper investigates the effect of reservoir operation on downstream water quality. This is accomplished by the following procedures. An automated channel network extracting system, C-NES, is used to extract channel network from Digital Elevation Model and a distributed rainfall-runoff model is adopted to estimate the streamflows. The relationsh...
Article
Full-text available
The purpose of this study is to develop a numerical model to simulate the behavior of the head potential fluctuation in subsurface flow. Numerical and analytical solutions are presented. Impacts of the storativity and porosity on the head potential fluctuation are investigated in this paper. It is found, in one-dimensional subsurface flow, that the...
Article
This study investigates the characteristics of the interface between the soil granules and the fluid, which would have an important influence on organic reactions during clean up ground water pollution. Experiments are conducted to investigate the dynamic shape of the wetting front. A model is proposed to calculate the interfaced area between the f...
Article
A Monte Carlo simulation experiment was conducted to explore the relationships between land use, climate, and water supply yields. A watershed streamflow and sediment yield model was coupled with a reservoir model and used to estimate storage-yield relationships for otherwise identical 5,000-ha forested, agricultural, and urban watersheds using wea...
Conference Paper
Fractal geometry, due to its ability for describing natural objects better than Euclidean geometry, has attracted great interests ever since Mandelbrot presented the concept of fractals in 1975. This paper investigates the fractal characteristic of eight individual river plan forms in Taiwan. Analyzed using the Richardson plot, these rivers have si...
Article
Full-text available
This research investigated into the influence of irrigation water requirement with the irrigation operation including channel supply, wire supply and pond supply. Taoyuan Channel #2 Feeder in North Taiwan was selected as the study area. The agriculture irrigation system model was established by adapting Vensim model and the irrigation water supply...
Article
Full-text available
For multireservoir systems for hydropower purpose, the best strategy of joint operation is to release water firstly from the reservoir with the higher hydropower efficiency for achieving the highest benefits of the whole system. Considering scarcity of water resources, however, the operation practice is to follow a proper set of rule curves so as n...
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