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Papers by Kuo-chin Hsu

Journal of Water and Climate Change

Despite the mountainous watersheds being important for the ecosystem, water resources, and hydrop... more Despite the mountainous watersheds being important for the ecosystem, water resources, and hydropower, little hydrological data has been collected. This data scarcity makes it difficult to evaluate their hydrologic response to climate change. This study integrated short-term hydrological data with physics-based meteorological and hydrological models to measure the impact of climate change on future water scarcity in the Wuling Mountain Watershed, Taiwan. Twenty-eight-month hydrological datasets from 2013 to 2015 were used for the hydrological characterization. Scenarios from CMIP5 were selected for the climate projection for the period 2021–2040 based on the inferred 1986–2005 baseline data. The results showed that precipitation, water percolation, and streamflow will decrease by about 10% and increase by about 20–25% in the dry and wet seasons, respectively. The evapotranspiration is lower than that of the baseline in January, March, and December, whereas it can be as high as 4% du...

In this study, the stable isotope values of oxygen and hydrogen were used to identify the seasona... more In this study, the stable isotope values of oxygen and hydrogen were used to identify the seasonal contribution ratios of precipitation to groundwater recharge in the Hualien River basin of eastern Taiwan. The differences and correlations of isotopes in various water bodies were examined to evaluate the groundwater recharge sources for the Hualian River basin and the interrelations between groundwater and surface water. Proportions of recharge sources were calculated based on the results of the mass balance analysis of the isotope composition of hydrogen and oxygen in the basin. Mountain river water accounted for 83% and plain rainfall accounted for 17% of the groundwater recharge in the Huanlian River basin. Using the mean d-values, a comparison of d-values of precipitation and groundwater indicates the groundwater consists of 75.5% wet seasonal sources and 24.5% dry seasonal sources, representing a distinct seasonal variation of groundwater recharge in the study area. Comparisons between hydrogen and oxygen isotopes in rainwater showed that differences in the amount of rainfall resulted in depleted oxygen and hydrogen isotopes for precipitation in wet seasons as compared to dry seasons. The river water contained more depleted hydrogen and oxygen isotopes than was the case for precipitation, implying that the river water mainly came from the upstream catchment. In addition, the hydrogen and oxygen isotopes in the groundwater slightly deviated from the hydrogen and oxygen isotopic meteoric water line in Huanlian. Therefore, the

$Research paper thumbnail of Stochastic analysis of groundwater flow in a two‐dimensional generalized fractal field$

Journal of the Chinese Institute of Engineers, 2008

Stochastic analysis of groundwater flow in a generalized fractal field is performed in this study... more Stochastic analysis of groundwater flow in a generalized fractal field is performed in this study. The random field is described by fractional Levy motion (fLm), which is a generalized version of traditional fractional Brownian motion (fBm) and is superior to describe a field with a high degree of variability. A truncated power variogram of the fLm is derived using the weighted superposition of mutually uncorrelated exponential variograms. When the Levy index of fLm α equals 2, the fBm is recovered. When the upper and lower cutoffs of the truncated power variogram are close, the stationary exponential model can be well approximated. First‐order perturbation analyses of flow in a two‐dimensional fLm field are performed and results are compared to those in the stationary exponential and fractal fBm fields. Since the proposed general fractal model has broader applications than the stationary and fBm models, it is versatile enough to simulate flow in different scenarios and provide more accurate modeling results.

Water Resources Research, 2013

In this study, we developed a stochastic estimator for characterizing the hydraulic heterogeneity... more In this study, we developed a stochastic estimator for characterizing the hydraulic heterogeneity in both unsaturated and saturated zones of unconfined aquifers using transient drawdown data from sequential pumping tests. This estimator was built upon the successive linear estimator by Yeh et al. (1996), the simultaneous successive linear estimator by Xiang et al. (2009), and the 3-D finite element program for flow and transport through heterogeneous media by Srivastava and Yeh (1992). The estimator was tested afterward using simulated data sets of sequential pumping tests in a synthetic unconfined aquifer where saturated conductivity, specific storage, saturated water content, and pore-size distribution parameter vary spatially in three dimensions. Test results show that the estimator is able to produce parameter fields that capture the overall 3-D pattern of the true heterogeneous parameter fields. We subsequently validated the estimated parameter fields by assessing their ability to predict drawdowns during an independent pumping test, which was not used during the estimation phase. Results of the validation show that the predicted drawdowns based on the estimated heterogeneous parameter fields are in close agreement with the true drawdowns. In addition, predicted drawdowns based on the parameter fields from the joint interpretation are superior to those based on the parameters estimated from the homogeneous conceptual model. Lastly, while many field experiments are necessary to fully assess the robustness of this estimator and sequential pumping tests, results of this study suggest they are a promising characterization technique for unconfined aquifers.

Journal of Water and Climate Change, 2018

Extreme hydrological events have occurred in many climate zones in recent decades. Most important... more Extreme hydrological events have occurred in many climate zones in recent decades. Most importantly, the water distribution in hydrological components has changed with apparent variations in climate. The associated impact on water resources is of concern because an understanding of the hydrological response mechanism is necessary for human survival. In this study, we compare precipitation and streamflow responses to climate variations in two different climate zones. Continental-scale frigid zone (CSFZ) data were collected from Russia, while island-scale subtropical zone (ISSZ) data were collected from Taiwan. The results show that the teleconnection of the precipitation between the ISSZ and CSFZ is subtle and is linked to global atmospheric conditions. The daily maximum precipitation and the duration without precipitation increased in both the CSFZ and the ISSZ. The streamflow response became more extreme in the ISSZ and was associated with pronounced dry and wet seasons. In contras...

Comment on hess-2021-403 Kuo-Chin Hsu (Referee) Referee comment on "Karst spring discharge modeli... more Comment on hess-2021-403 Kuo-Chin Hsu (Referee) Referee comment on "Karst spring discharge modeling based on deep learning using

Computers and Geotechnics, 2021

Abstract The fundamental study of coupled thermal–hydraulic-mechanical (THM) systems is an import... more Abstract The fundamental study of coupled thermal–hydraulic-mechanical (THM) systems is an important issue in multi-physical fields. This study developed a THM model in which the hydraulic and mechanical effects are fully coupled and the temperature change serves as the perturbation source of the system. A porothermoelasticity model was applied to investigate the cross-interactions among the temperature, change in pore water pressure, and displacement of a buffer material in the near-field and a host rock in the far-field with the conceptual model in a nuclear waste repository. The results show that the size scale of the domain of interest and the THM properties play important roles in the coupled THM system. The changes in pore water pressure depended on the combined effect of the deformation of the porous space and pore water controlled by the thermal expansion coefficients of the solids and fluids. Stochastic analyses show that the uncertainties of variables varied spatio-temporally due to the thermal influences and approached zero due to the presence of a stable condition. The cross-interactions between displacement and change in pore water pressure induced by the thermal effect were complex and can be determined from statistical moment analyses.

Journal of Asian Earth Sciences, 2015

Groundwater level variations associated with earthquake events may reveal useful information. Thi... more Groundwater level variations associated with earthquake events may reveal useful information. This study estimates the extent of stress influence, defined as the distance over which an earthquake can induce a step change of the groundwater level, using earthquake-triggering groundwater level variations in Taiwan. Groundwater variations were first characterized based on the dynamics of groundwater level changes dominantly triggered by earthquakes. The step-change data in co-seismic groundwater level variations were used to analyze the extent of stress influence for earthquakes. From the data analysis, the maximum extent of stress influence is 250 km around Taiwan. A two-dimensional approach was adopted to develop two models for estimating the maximum extent of stress influence for earthquakes. From the developed models, the extent of stress influence is proportional to the earthquake magnitude and inversely proportional to the groundwater level change. The model equations can be used to calculate the influence radius of stress from an earthquake by using the observed change of groundwater level and the earthquake magnitude. The models were applied to estimate the area of anomalous stress, defined as the possible areas where the strain energy is accumulated, using the cross areas method. The results show that the estimated area of anomalous stress is close to the epicenter. Complex geological structures and material heterogeneity and anisotropy may explain this disagreement. More data collection and model refinements can improve the proposed model. This study shows the potential of using groundwater level variations for capturing seismic information. The proposed concept of extent of stress influence can be used to estimate the earthquake effect in hydraulic engineering, mining engineering, and carbon dioxide sequestration, etc. This study provides a concept for estimating the possible areas of anomalous stress for a forthcoming earthquake.

Journal of Hydrology, 2009

In this study, a stochastic model is proposed to solve poroelastic problems in heterogeneous poro... more In this study, a stochastic model is proposed to solve poroelastic problems in heterogeneous porous media. The model is constructed using the first-order second-moment method to investigate the dynamic behaviors of statistical mean and covariance of the change in pore water pressure and displacement. Although several variables can be simultaneously treated as random in the model, the Darcy conductivity is selected as the only random variable for this preliminary investigation due to its large variation compared to other mechanical and hydrogeological properties in natural environments. The constructed model is general in multiple dimensions; however, the one-dimensional case is taken as an example to demonstrate the use of the stochastic model. This model is validated using analytical and numerical solutions from the literature. Numerical experiments are then performed to investigate the boundary effects on the coupled fluid pressure and mechanical deformation in elastic porous media. The results show that the dynamic behavior of a coupled flow-stress system is more complex than a system that does not consider the deformation of porous media. Loading effects on deformation and pore pressure are instantaneous while the effect of discharge takes time to propagate from the boundary through the whole domain. Both loading and discharge boundary conditions can significantly affect the uncertainty of the system response. In the scenario combining loading at the top boundary and discharge at the bottom boundary, the mean total settlement and the average flux satisfy the relationship of superposition to be the sum of the separated effects of loading at top boundary and discharge at bottom boundary, but the variances do not. The proposed stochastic poroelastic method can be applied to hydrological issues that concern the interaction of flow and geomechanics.

Earth, Planets and Space, 2010

established a groundwater observation network consisting of 16 wells. Most of these were located ... more established a groundwater observation network consisting of 16 wells. Most of these were located along active faults for research on earthquake-related groundwater changes. They were selected mainly from among the 550 groundwater observation wells of the Water Resources Agency (WRA), which monitors and manages groundwater resources in Taiwan. The groundwater level was observed at a resolution of 0.2 mm at the wells. The depths of the well screens ranged between 80 and 252 m. Groundwater level data at six of the 16 wells were analyzed between 2003 and 2006 in an evaluation of such data for use in detecting earthquake-related groundwater level changes. The strain sensitivities of the groundwater level at these six wells ranged between 0.1 and 0.5 mm/10 −9 , indicating that an analysis of groundwater level data at these six wells can detect volumetric strain changes on the order of 10 −9. Coseismic and/or postseismic groundwater level changes associated with 17 earthquakes in and around Taiwan whose magnitudes were ≥6 were also analyzed. Our analysis shows that ground shaking seems the main reason for earthquake-related changes but that the acceleration of ground shaking cannot always explain the observed groundwater level changes.

Storm water or overland flow can be captured and injected into a soil trench or infiltration gall... more Storm water or overland flow can be captured and injected into a soil trench or infiltration gallery attached to a siphon and emplaced adjacent to a stream or arroyo bank. This injected soil water can be used by stream side vegetation for wildlife habitat, bank stabilization or other purposes. The siphon system has three hydrologically-distinct flow regimes: (1) infiltrating flow, (2) cycling outflow, and (3) constant outflow. These flow regimes are dependent upon infiltration gallery design, soil hydraulic conductivity, and rainfall intensity. The design is low-cost and is predicted to be selfcleaning and low maintenance.

Hydrological Processes, 2009

The interaction of geomechanics and flow within a soil body induces deformation and pore pressure... more The interaction of geomechanics and flow within a soil body induces deformation and pore pressure change. Deformation may change hydrogeological and elastic properties, which alters the mechanical behaviour and results in non-linearity. To investigate this interaction effect in a heterogeneous porous medium, a stochastic poroelastic model is proposed. Monte Carlo simulations are performed to determine the mean and uncertainty of the parameter changes, displacement, and change in pore water pressure. Hydraulic conductivity is treated as the only random variable in the coupled geomechanics-flow system due to its large variation compared to other mechanical and hydrogeological properties in natural environments. The three considered non-linear models for the interaction between parameters and deformation are those that consider (1) porosity and hydraulic conductivity; (2) porosity and Young's modulus; and (3) a combined effect that includes porosity, hydraulic conductivity, and Young's modulus. Boundary effects on the coupled system are also explored. The relationships between changes of porosity, hydraulic conductivity, and Young's modulus are analytically shown to be non-linear. Among the considered parameters, the deformation effect induces the largest reduction in hydraulic conductivity. The deformationinduced change in hydraulic conductivity shows the most significant effect on the mean and variance of the change in pore water pressure and displacement, while changes in Young's modulus have the least effect. When the deformation effect is considered, the superposition relationship does not exist in the mean displacement and mean change in pore water pressure for the three scenarios considered; it exists for the case without deformation effects. Deformation also causes a reduction in the effective hydraulic conductivity for the whole domain. The scenario that considers both loading and discharge boundaries has larger changes in hydrogeological and geo-mechanical parameters than those in scenarios that consider loading and discharge boundaries separately. The results indicate that the interaction between deformation and changes in parameters has a profound effect on the poroelastic system. The effect of deformation should thus be considered in modelling and practice. Copyright  2009 John Wiley & Sons, Ltd.