Chong-Yu Xu - Academia.edu (original) (raw)

Papers by Chong-Yu Xu

Research paper thumbnail of Bivariate frequency analysis of nonstationary low-flow series based on the time-varying copula

Hydrological Processes, 2014

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Research paper thumbnail of Stationarity of annual flood peaks during 1951–2010 in the Pearl River basin, China

Journal of Hydrology, 2014

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Research paper thumbnail of Characteristics of water surplus and deficit change in 10 major river basins in China during 1961-2010

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Research paper thumbnail of An investigation of enhanced recessions in Poyang Lake: Comparison of Yangtze River and local catchment impacts

Journal of Hydrology, 2014

ABSTRACT Changes in lake hydrological regimes and the associated impacts on water supplies and ec... more ABSTRACT Changes in lake hydrological regimes and the associated impacts on water supplies and ecosystems are internationally recognized issues. During the past decade, the persistent dryness of Poyang Lake (the largest freshwater lake in China) has caused water supply and irrigation crises for the 12.4 million inhabitants of the region. There is conjecture as to whether this dryness is caused by climate variability and/or human activities. This study examines long-term datasets of catchment inflow and Lake outflow, and employs a physically-based hydrodynamic model to explore catchment and Yangtze River controls on the Lake’s hydrology. Lake water levels fell to their lowest during 2001-2010 relative to previous decades. The average Lake size and volume reduced by 154 km2 and 11×108 m3 during the same period, compared to those for the preceding period (1970-2000). Model simulations demonstrated that the drainage effect of the Yangtze River was the primary causal factor. Modelling also revealed that, compared to climate variability impacts on the Lake catchment, modifications to Yangtze River flows from the Three Gorges Dam have had a much greater impact on the seasonal (September-October) dryness of the Lake. Yangtze River effects are attenuated in the Lake with distance from the River, but nonetheless propagate some 100 km to the Lake’s upstream limit. Proposals to build additional dams in the upper Yangtze River and its tributaries are expected to impose significant challenges for the management of Poyang Lake. Hydraulic engineering to modify the flow regime between the Lake and the Yangtze River would somewhat resolve the seasonal dryness of the Lake, but will likely introduce other issues in terms of water quality and aquatic ecosystem health, requiring considerable further research.

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Research paper thumbnail of Large-scale hydrology: observations and modelling

Hydrology Research, 2013

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Research paper thumbnail of Editorial: New category of Invited Papers

Hydrology Research, 2014

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Research paper thumbnail of Application to Ungauged Catcbiients

More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km2 have been studi... more More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km2 have been studied by means of a physically-based stochastic water balance model. The parameter values derived from cali- bration of the model were regionally mapped for the study region. Associations between model parameters and basin lithological characte- ristics were established and tested. The results show

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Research paper thumbnail of Impact of projected climate change on the hydrology in the headwaters of the Yellow River basin

Hydrological Processes, 2015

ABSTRACT Located in the northeast of Tibetan plateau, the headwaters of the Yellow River Basin is... more ABSTRACT Located in the northeast of Tibetan plateau, the headwaters of the Yellow River Basin is very vulnerable to climate change. In this study, we used the Soil and Water Assessment Tool (SWAT) model to assess the impact of future climate change on this region's hydrological components for the near future period of 2013-2042 under three emission scenarios A1B, A2 and B1. The uncertainty in this evaluation was considered by employing Bayesian Model Averaging (BMA) approach on GCM multimodel ensemble projections. First, we evaluated the capability of the SWAT model for streamflow simulation in this basin. Second, the GCMs monthly ensemble projections were downscaled to daily climate data using the bias-correction and spatial disaggregation (BCSD) method, and then were utilized as input into the SWAT model. The results indicate that: (1) the SWAT model exhibits a good performance for both calibration and validation periods after adjusting parameters in snowmelt module and establishing elevation bands in subbasins. (2) The projected precipitation suggests a general increase under all three scenarios, with a larger extent in both A1B and B1 and a slight variation for A2. With regard to temperature, all scenarios show pronounced warming trends, of which A2 displays the largest amplitude. (3) In the terms of total runoff from the whole basin, there is an increasing trend in the future streamflow at Tangnaihai gauge under A1B and B1 while A2 scenario is characterized by a declining trend. Spatially, A1B and B1 scenarios demonstrate increasing trends across most of the region. Groundwater and surface runoffs indicate similar trends with total runoff whereas all three scenarios exhibit an increase in actual evapotranspiration. Generally, both A1B and B1 scenarios suggest a warmer and wetter tendency over the HYRB in the forthcoming decades while the case for A2 indicates a warmer and drier trend. Findings from this study can provide beneficial reference to water resource and eco-environment management strategies for governmental policymakers. This article is protected by copyright. All rights reserved.

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Research paper thumbnail of Remote Sensing Monitoring Study for the Tendency of Qinghai Lake’s Water Area in Last 41 Years

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Research paper thumbnail of Modeling actual evapotranspiration with routine meteorological variables in the data-scarce region of the Tibetan Plateau: Comparisons and implications

Journal of Geophysical Research: Biogeosciences

Quantitative estimation of actual evapotranspiration (ETa) by in-situ measurements and mathematic... more Quantitative estimation of actual evapotranspiration (ETa) by in-situ measurements and mathematical modeling is a fundamental task for physical understanding of ETa as well as the feedback mechanisms between land and the ambient atmosphere. However, the ETa information in the Tibetan Plateau (TP) has been greatly impeded by the extremely sparse ground observation network in the region. Approaches for estimating ETa solely from routine meteorological variables are therefore important for investigating spatiotemporal variations of ETa in the data-scarce region of the TP. Motivated by this need, the complementary relationship (CR) and Penman-Monteith approaches were evaluated against in-situ measurements of ETa on a daily basis in an alpine steppe region of the TP. The former includes the Nonlinear Complementary Relationship (Nonlinear-CR) as well as the Complementary Relationship Areal Evapotranspiration (CRAE) models, while the latter involves the Katerji-Perrier and the Todorovic mo...

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Research paper thumbnail of Implementation and testing of routing algorithms in the distributed Hydrologiska Byråns Vattenbalansavdelning model for mountainous catchments

Hydrology Research, 2014

ABSTRACT The main purpose of this study was to implement and test routing algorithms in the distr... more ABSTRACT The main purpose of this study was to implement and test routing algorithms in the distributed Hydrologiska Byråns Vattenbalansavdelning (HBV) model with the emphasis of obtaining a most suitable routing algorithm for large mountainous catchments. Two routing algorithms were built into the grid-based HBV model and tested on the Losna (11,213 km2) and the Norsfoss (18,932 km2) catchments in central southern Norway. In the first algorithm, runoff is first routed from cell to cell and hydrographs are re-calculated at each cell, and then runoff is routed by the Muskingum–Cunge method in river channels. The second algorithm is a source-to-sink method, which routes runoff of all cells to the catchment outlet as a function of local slope and a calibrated velocity parameter. The routing approaches were compared at different spatial resolutions (i.e. 1, 5 and 10 km) in daily streamflow simulation. Additionally, the elevation band-based semi-distributed model was also compared with the distributed models. The results show that the distributed HBV models are able to perform better than the elevation band-based model, and hillslope routing is crucial in the mountainous catchments. However, incorporating the Muskingum–Cunge channel routing does not add value to the simulation of daily runoff in the mountainous catchments.

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Research paper thumbnail of Integrating a glacier retreat model into a hydrological model – Case studies of three glacierised catchments in Norway and Himalayan region

Journal of Hydrology, 2015

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Research paper thumbnail of Hydrological projections under climate change in the near future by RegCM4 in Southern Africa using a large-scale hydrological model

Journal of Hydrology, 2015

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Research paper thumbnail of Relative Importance Analysis of a Refined Multi-parameter Phosphorus Index Employed in a Strongly Agriculturally Influenced Watershed

Water, Air, & Soil Pollution, 2015

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Research paper thumbnail of Estimation of Monthly River Discharge from Danish Catchments

To simulate the nutrient loading of Danish coastal waters, river discharge from unmonitored areas... more To simulate the nutrient loading of Danish coastal waters, river discharge from unmonitored areas must be assessed. In an attempt to identify the most suitable method, for this purpose eight different versions of the three-parameter monthly water balance model "MWB-3" were tested on data from various Danish catch- ments for the period 1989-97. The model with the highest R2 and

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Research paper thumbnail of Narrowing the Gap Between GCMS'Ability and Hydrology Need-A Review

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Research paper thumbnail of Hydrological modeling in Climate change studies, progress and challenges

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Research paper thumbnail of Avrinning: Lärobok för kurs Avrinning

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Research paper thumbnail of Hydrological Modeling: lärobok för kurs Hydrologisk Analys och Modellering

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Research paper thumbnail of Solicited abstract: Global hydrological modeling and models

The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th... more The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th century arising in response to three types of engineering problems: (1) urban sewer design, (2) land reclamation drainage systems design, and (3) reservoir spillway design. Since then numerous empirical, conceptual and physically-based models are developed including event based models using unit hydrograph

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Research paper thumbnail of Bivariate frequency analysis of nonstationary low-flow series based on the time-varying copula

Hydrological Processes, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Stationarity of annual flood peaks during 1951–2010 in the Pearl River basin, China

Journal of Hydrology, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characteristics of water surplus and deficit change in 10 major river basins in China during 1961-2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of An investigation of enhanced recessions in Poyang Lake: Comparison of Yangtze River and local catchment impacts

Journal of Hydrology, 2014

ABSTRACT Changes in lake hydrological regimes and the associated impacts on water supplies and ec... more ABSTRACT Changes in lake hydrological regimes and the associated impacts on water supplies and ecosystems are internationally recognized issues. During the past decade, the persistent dryness of Poyang Lake (the largest freshwater lake in China) has caused water supply and irrigation crises for the 12.4 million inhabitants of the region. There is conjecture as to whether this dryness is caused by climate variability and/or human activities. This study examines long-term datasets of catchment inflow and Lake outflow, and employs a physically-based hydrodynamic model to explore catchment and Yangtze River controls on the Lake’s hydrology. Lake water levels fell to their lowest during 2001-2010 relative to previous decades. The average Lake size and volume reduced by 154 km2 and 11×108 m3 during the same period, compared to those for the preceding period (1970-2000). Model simulations demonstrated that the drainage effect of the Yangtze River was the primary causal factor. Modelling also revealed that, compared to climate variability impacts on the Lake catchment, modifications to Yangtze River flows from the Three Gorges Dam have had a much greater impact on the seasonal (September-October) dryness of the Lake. Yangtze River effects are attenuated in the Lake with distance from the River, but nonetheless propagate some 100 km to the Lake’s upstream limit. Proposals to build additional dams in the upper Yangtze River and its tributaries are expected to impose significant challenges for the management of Poyang Lake. Hydraulic engineering to modify the flow regime between the Lake and the Yangtze River would somewhat resolve the seasonal dryness of the Lake, but will likely introduce other issues in terms of water quality and aquatic ecosystem health, requiring considerable further research.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Large-scale hydrology: observations and modelling

Hydrology Research, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial: New category of Invited Papers

Hydrology Research, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Application to Ungauged Catcbiients

More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km2 have been studi... more More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km2 have been studied by means of a physically-based stochastic water balance model. The parameter values derived from cali- bration of the model were regionally mapped for the study region. Associations between model parameters and basin lithological characte- ristics were established and tested. The results show

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of projected climate change on the hydrology in the headwaters of the Yellow River basin

Hydrological Processes, 2015

ABSTRACT Located in the northeast of Tibetan plateau, the headwaters of the Yellow River Basin is... more ABSTRACT Located in the northeast of Tibetan plateau, the headwaters of the Yellow River Basin is very vulnerable to climate change. In this study, we used the Soil and Water Assessment Tool (SWAT) model to assess the impact of future climate change on this region's hydrological components for the near future period of 2013-2042 under three emission scenarios A1B, A2 and B1. The uncertainty in this evaluation was considered by employing Bayesian Model Averaging (BMA) approach on GCM multimodel ensemble projections. First, we evaluated the capability of the SWAT model for streamflow simulation in this basin. Second, the GCMs monthly ensemble projections were downscaled to daily climate data using the bias-correction and spatial disaggregation (BCSD) method, and then were utilized as input into the SWAT model. The results indicate that: (1) the SWAT model exhibits a good performance for both calibration and validation periods after adjusting parameters in snowmelt module and establishing elevation bands in subbasins. (2) The projected precipitation suggests a general increase under all three scenarios, with a larger extent in both A1B and B1 and a slight variation for A2. With regard to temperature, all scenarios show pronounced warming trends, of which A2 displays the largest amplitude. (3) In the terms of total runoff from the whole basin, there is an increasing trend in the future streamflow at Tangnaihai gauge under A1B and B1 while A2 scenario is characterized by a declining trend. Spatially, A1B and B1 scenarios demonstrate increasing trends across most of the region. Groundwater and surface runoffs indicate similar trends with total runoff whereas all three scenarios exhibit an increase in actual evapotranspiration. Generally, both A1B and B1 scenarios suggest a warmer and wetter tendency over the HYRB in the forthcoming decades while the case for A2 indicates a warmer and drier trend. Findings from this study can provide beneficial reference to water resource and eco-environment management strategies for governmental policymakers. This article is protected by copyright. All rights reserved.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Remote Sensing Monitoring Study for the Tendency of Qinghai Lake’s Water Area in Last 41 Years

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Modeling actual evapotranspiration with routine meteorological variables in the data-scarce region of the Tibetan Plateau: Comparisons and implications

Journal of Geophysical Research: Biogeosciences

Quantitative estimation of actual evapotranspiration (ETa) by in-situ measurements and mathematic... more Quantitative estimation of actual evapotranspiration (ETa) by in-situ measurements and mathematical modeling is a fundamental task for physical understanding of ETa as well as the feedback mechanisms between land and the ambient atmosphere. However, the ETa information in the Tibetan Plateau (TP) has been greatly impeded by the extremely sparse ground observation network in the region. Approaches for estimating ETa solely from routine meteorological variables are therefore important for investigating spatiotemporal variations of ETa in the data-scarce region of the TP. Motivated by this need, the complementary relationship (CR) and Penman-Monteith approaches were evaluated against in-situ measurements of ETa on a daily basis in an alpine steppe region of the TP. The former includes the Nonlinear Complementary Relationship (Nonlinear-CR) as well as the Complementary Relationship Areal Evapotranspiration (CRAE) models, while the latter involves the Katerji-Perrier and the Todorovic mo...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Implementation and testing of routing algorithms in the distributed Hydrologiska Byråns Vattenbalansavdelning model for mountainous catchments

Hydrology Research, 2014

ABSTRACT The main purpose of this study was to implement and test routing algorithms in the distr... more ABSTRACT The main purpose of this study was to implement and test routing algorithms in the distributed Hydrologiska Byråns Vattenbalansavdelning (HBV) model with the emphasis of obtaining a most suitable routing algorithm for large mountainous catchments. Two routing algorithms were built into the grid-based HBV model and tested on the Losna (11,213 km2) and the Norsfoss (18,932 km2) catchments in central southern Norway. In the first algorithm, runoff is first routed from cell to cell and hydrographs are re-calculated at each cell, and then runoff is routed by the Muskingum–Cunge method in river channels. The second algorithm is a source-to-sink method, which routes runoff of all cells to the catchment outlet as a function of local slope and a calibrated velocity parameter. The routing approaches were compared at different spatial resolutions (i.e. 1, 5 and 10 km) in daily streamflow simulation. Additionally, the elevation band-based semi-distributed model was also compared with the distributed models. The results show that the distributed HBV models are able to perform better than the elevation band-based model, and hillslope routing is crucial in the mountainous catchments. However, incorporating the Muskingum–Cunge channel routing does not add value to the simulation of daily runoff in the mountainous catchments.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Integrating a glacier retreat model into a hydrological model – Case studies of three glacierised catchments in Norway and Himalayan region

Journal of Hydrology, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hydrological projections under climate change in the near future by RegCM4 in Southern Africa using a large-scale hydrological model

Journal of Hydrology, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Relative Importance Analysis of a Refined Multi-parameter Phosphorus Index Employed in a Strongly Agriculturally Influenced Watershed

Water, Air, & Soil Pollution, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Estimation of Monthly River Discharge from Danish Catchments

To simulate the nutrient loading of Danish coastal waters, river discharge from unmonitored areas... more To simulate the nutrient loading of Danish coastal waters, river discharge from unmonitored areas must be assessed. In an attempt to identify the most suitable method, for this purpose eight different versions of the three-parameter monthly water balance model "MWB-3" were tested on data from various Danish catch- ments for the period 1989-97. The model with the highest R2 and

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Narrowing the Gap Between GCMS'Ability and Hydrology Need-A Review

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hydrological modeling in Climate change studies, progress and challenges

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Avrinning: Lärobok för kurs Avrinning

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hydrological Modeling: lärobok för kurs Hydrologisk Analys och Modellering

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Solicited abstract: Global hydrological modeling and models

The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th... more The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th century arising in response to three types of engineering problems: (1) urban sewer design, (2) land reclamation drainage systems design, and (3) reservoir spillway design. Since then numerous empirical, conceptual and physically-based models are developed including event based models using unit hydrograph

Bookmarks Related papers MentionsView impact