Xueping Gao’s research while affiliated with Tianjin University and other places

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Publications (56)


Contribution for lake phytoplankton community succession under multi-source artificial hydrological regulation
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November 2024

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22 Reads

Journal of Environmental Management

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Guoyu Wang

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Fig. 1. Study area and numerical model. (a) The location and water system overview of the Baiyangdian Lake and (b) the setting of model grid. The water inlet from the upstream reservoirs, the South-to-North (S-N), and the Yellow River to Hebei (Y-H) water diversion projects are labeled in (b1); the five locations marked red in (b1) are considered as core areas to analyze the evolution of water quality. The division of vegetated and nonvegetated grid with different roughness factor for hydrodynamic modeling are denoted in (b2)-(b3).
Fig. 2. Variations in flow of different water replenishment scenarios. Scenario numbers S1, S2, S3, S4, and S5 are the temporal division of spring, pre-flood, flood, post-flood, and autumn and winter stage, respectively. SX-0 indicates the scenario only has base flow, while SX-1, SX-2, and SX-3 are water replenishment scenarios with varied proportions of receiving water from different sources.
Fig. 3. The validation of the hydrodynamic and water quality model established for the Baiyangdian Lake.
Fig. 8. The heterogeneity in aquatic system evolution induced by the water replenishment. The abbreviations W, N, D, G, and Q denote the five key areas of the lake, as illustrated in Fig. 6.
Water quality evolution of water-receiving lakes under the impact of multi-source water replenishments
  • Article
  • Full-text available

June 2024

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89 Reads

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3 Citations

Journal of Hydrology Regional Studies

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Oxygen evolution and its drivers in a stratified reservoir: A supply-side perspective for informing hypoxia alleviation strategies

April 2024

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101 Reads

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2 Citations

Water Research

Hypoxia in stratified waters greatly threatens aquatic ecology and societal development owing to enhanced nutrient discharge and increasing global temperature. Current research predominantly alleviates hypoxia by reducing dissolved oxygen (DO) consumption or conducting hypolimnetic oxygenation, yet their implementation has encountered bottlenecks. Therefore, this study explores the potential of increasing the inherent DO supplies in stratified reservoirs to mitigate hypoxia. High-frequency in situ observations and massive modeling experiments are integrated to discern the DO supply mode and the dominant driver of DO evolution. Results indicate that periodic thermodynamic conditions determine the DO supply relationships between oxygen sources (inflow carriage, reaeration, and photosynthesis) for different water layers. Thermal stratification causes the hypolimnion to rely mostly on the inflow for DO supply, leading to a fragile budget prone to hypoxia. However, episodic hydrodynamic events (turnover, wind stir, density current, and flood) can promote DO supply and inhibit hypoxia. Temperature and DO regimes are primarily driven by outflow conditions, followed by inflow and meteorology conditions. Furthermore, hypolimnetic hypoxia can be regulated by altering inflow volume, outflow volume, and outlet elevation. These findings highlight the importance of longitudinal solute exchange in DO evolution in stratified reservoirs, providing a basis for alleviating hypoxia through cascade reservoir operations.


Modeling Physical and Physiological Processes Reveals the Role of Turbulence in the Prerequisites for Microcystis Blooms

February 2024

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231 Reads

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2 Citations

Harmful algal blooms of Microcystis have become a global problem. Turbulence, a determining factor affecting blooms, not only disperses surface scum but also controls the growth of Microcystis. Numerous studies have analyzed the effects of turbulence on the growth and colony size of Microcystis in laboratories, but the turbulence thresholds for Microcystis growth and colony disaggregation in the field are difficult to determine due to the complex environment. In addition, the quantitative contribution of turbulence‐driven blooms and the intrinsic mechanisms of the spatial distribution responding to turbulence are unclear. In this study, a fully integrated filed scale computational model focusing on turbulence‐driven blooms was developed, which incorporates physical processes (turbulence‐induced vertical mixing, VMT) and physiological processes such as buoyancy‐controlling transport (BCT), turbulence‐induced colony size variation (CSV), and growth rate variation (GRV). We performed model sensitivity analysis and evaluated the effects of turbulence intensity and duration on the biomass and vertical distribution of Microcystis. The results show that the optimal turbulence dissipation rate for Microcystis growth in the field is 1.0 × 10⁻⁵ m²/s³ and the critical turbulence dissipation rate for aggregation distribution is 3.81 × 10⁻⁶ m²/s³ in shallow lakes. A quantitative comparison of the effects of physical/physiological processes on blooms shows that physiological processes (CSV, GRV, and BCT) are critical for biomass enrichment, and the accumulation of Microcystis at the water surface is dominated by physical processes (VMT). This study reveals the mechanisms of turbulence‐driven Microcystis blooms and provides new insights for algal bloom prediction and control.


Hydrodynamics, Diagenesis and Hypoxia Variably Drive Benthic Oxygen Flux in a River‐Reservoir System

January 2024

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304 Reads

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7 Citations

Benthic oxygen flux with complex spatiotemporal variations is essential for the global budget of carbon dioxide and the regional security of water quality and ecology, but its dominant driver under different circumstances has yet to be identified. In this study, a parametric scheme of oxygen flux was proposed and validated with aquatic eddy correlation measurements and then coupled with a diagenesis model and a water environment model. The coupled model was applied to a river‐reservoir with significant environmental gradients in hydrodynamics, diagenesis, and hypoxia, which are three factors that competitively drive the variation in benthic oxygen flux. The results indicate that hydrodynamics dominate the flux in the riverine and thalweg areas, diagenesis is the dominant driver of the lacustrine and bank areas, and hypoxia shows dominance only in the hypolimnetic anoxic area. In general, diagenesis is the dominant driver of oxygen flux in river‐reservoirs, followed by hydrodynamics, both of which are more prominent than hypoxia. If the operated reservoir experiences a wet year, the dominance of hydrodynamics tends to increase, while that of diagenesis and hypoxia decreases. The three divers exhibit similar but more stable dominance in riverine systems than in reservoirs, while diagenesis becomes the exclusive driver of oxygen fluxes in lacustrine systems.


Sediment respiration dynamics and its contribution to carbon emissions in stratified reservoirs

November 2023

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62 Reads

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1 Citation

Journal of Environmental Management

Sediment respiration, the relation between dissolved oxygen (DO) attribution and carbon dioxide (CO2) emission, is an important index of the aquatic ecosystem and a key concern in the evaluation of reservoir cleanliness performance. To understand the sediment respiration dynamics regulated by the thermal stratification that is common in deep-water reservoirs, this study conducted in-situ measurements of thermal structures and benthic environments in the Daheiting Reservoir for 16 months. Then, the variations of DO and CO2 fluxes at the sediment-water interface (SWI) were obtained based on the aquatic eddy correlation method and the newly proposed virtual incubator method, respectively. The results show that the SWI fluxes dynamics can be decomposed into tendency variations dominated by thermal stratification and impulse variations induced by extreme events. The annual average SWI DO and CO2 fluxes of 3.80–6.62 and 1.92–3.15 mmol m−2⋅d−1 are estimated in the study site through the respiration dynamics, respectively, which CO2 flux is at a moderate level among the nearly 50 lakes and reservoirs worldwide but accounts for less than 15% of the total CO2 emission of this reservoir. Moreover, the sediment respiration quotient in stratified reservoirs is lower than in other aquatic environments, suggesting that the permanently flooded area is a weak net carbon source, while most carbon emissions from stratified reservoirs are carbon displacement or net carbon generated within the water. Sediment net carbon emissions correspond to human benefits such as flood control, power generation, and fisheries, whereas water net carbon emissions are usually not beneficial. Therefore, reducing net carbon emissions generated in the water may become an important way to achieve low-carbon operation of deep-water reservoirs.


Hyporheic exchange driven by emergent vegetation patches: Experiment and simulations

November 2023

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65 Reads

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4 Citations

Journal of Hydrology

The vegetated region is known as the “hot zone” for the exchange of substances in river systems, which causes an uneven pressure distribution at the sediment–water interface (SWI) and then forms hyporheic exchange (HE). However, as a common form of plant survival, the impact of vegetation patches on HE has received little research attention. In this study, laboratory experiment and numerical simulations were conducted to explore the effects of solid volume fraction within the patch (φ), the overlying water average velocity (U), and the streamwise distance of the patches (Sx) on HE. The results showed that the pressure along the SWI caused the spatial–temporal characteristics of HE at the vegetation patch (VP) scale and vegetation patch group (VG) scale. At the VP scale, the HE depth was influenced by φ, U, and Sx in increasing order, and increased with the increase in these values within a certain range. At the VG scale, the HE depth was positively correlated with φ and U and negatively correlated with Sx, and the spatial characteristics of HE were larger at this scale than at the VP scale. The HE flux was linearly related to φ and power functionally related to U. There was an asymptotic behavior of the effect of Sx on the HE flux, which means that the rate of change of the HE flux progressively decreases with Sx. The HE volume was influenced by Sx, φ, and U in increasing order and was positively correlated with all of these parameters. Based on the flow blockage parameter, Reynolds number (Re), and Sx, a prediction model of HE flux was developed. The results of this study provided further understanding of the role of vegetation patches in driving the HE process and may serve as a reference for vegetated river benthic habitat restoration.


Impacts of Ecological Water Supplement Projects on Fish Habitat Suitability in a High-leakage River in China

October 2023

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64 Reads

Journal of Hydrology

Ecological water supplement projects (EWSP) aimed at restoring damaged river ecosystems can change river hydrological processes, and loss of water through river leakage can potentially affect the spatiotemporal differences of river hydraulic factors, thus further affecting the habitat suitability of aquatic organisms. Therefore, assessing the impact of EWSP on habitats, considering leakage, is critical for high-leakage rivers recharging underlying and adjacent groundwater. In this study, a river habitat suitability simulation framework was established based on the surface water and groundwater coupling model and a fuzzy logic model. This framework was implemented to simulate the habitat suitability of a high-leakage reach of the Yongding River in China under different scenarios. The results showed that neglecting leakage would lead to overestimation of fish habitat suitability. The impacts of EWSP on the habitat were positive in spring; however, it was the opposite in autumn, which was affected by factors that led to spatiotemporal differences in leakage, such as topography and geology, water supplement season, and magnitude and duration of discharge. The optimal water supplement discharge of the Yongding River was 15–25 m3/s, which is consistent with the optimal discharge range recommended by the Tennant method. In the future, with the gradual decrease in leakage, habitat suitability will continue to improve, and the water quantity of EWSP required to maintain the same degree of weighted usable area will continue to decrease.


Multi-approach framework to estimate the mass flux at the sediment-water interface based on the effective diffusivity coefficient: A case study of the largest lake in North China

August 2023

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57 Reads

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2 Citations

Journal of Hydrology Regional Studies

Study region: Baiyangdian Lake, the largest freshwater lake on the North China Plain, is located in Xiong’an New Area of Hebei Province. Study focus: Physical, chemical, and biological reactions are active at the sediment-water interface and have a complex impact on the interfacial transport process. Based on the theory of the effective diffusion coefficient, combined with the analysis of sediment, in-situ observations, and a hydrodynamic model, we built a multi-approach framework to accurately estimate the interfacial mass flux and its temporal and spatial variations. New hydrological insights for the region: The results showed that the NH4 +-N release flux across the interface varies between 6.12 and 62.30 mg m−2 d−1. The transport processes in the Nanliuzhuang and Mapeng regions were dominated by the dispersive regime, whereas those in the remaining regions were dominated by the molecular regime. Under extreme weather conditions, such as typhoons, the mass flux is more than five times that under windless conditions. At this time, the framework to estimate the interfacial mass flux based on the effective diffusivity coefficient (FEIMF-EDC) can better reflect the sudden increase in mass flux caused by short-term strong hydrodynamic disturbances. This framework has a good application effect in shallow lakes with obvious spatiotemporal heterogeneity of sediment and hydrodynamics and can provide a basis for accurately formulating plans for water environment monitoring and management.


Citations (45)


... There is a wide range of d 15 N values among sampling points, with d 15 N values serving as an important indicator for analyzing the sources of TOC. The changes of d 15 N values with depth often indicate nitrogen cycling processes in the sediment such as the origin of organic matter, the degree of organic matter decomposition, and environmental changes.31,43,44 Higher d 15 N values typically indicate that TOC originates from aquatic ...

Reference:

Impact of Cascade Reservoir on the Sources of Organic Matter in Sediments of Lancang River
Oxygen evolution and its drivers in a stratified reservoir: A supply-side perspective for informing hypoxia alleviation strategies
  • Citing Article
  • April 2024

Water Research

... First and foremost, policies should account for the economic conditions and educational levels of various groups of tea farmers, as well as their perceptions of the environmental and health benefits of organic agriculture. Training and support programs must be flexible and targeted, effectively addressing the specific barriers faced by tea farmers during the transition to organic production [48][49][50]. Additionally, guidance on organic farming techniques and organic certification requirements should be actively promoted to assist farmers in connecting with the organic market and to boost their confidence in making the transition [51,52]. ...

Hydrodynamics, Diagenesis and Hypoxia Variably Drive Benthic Oxygen Flux in a River‐Reservoir System

... 31, 32 Nepf and other researchers have systematically studied various aspects of submerged vegetation under unidirectional flow condition, including turbulence structure, 33,34 sediment entrainment, [35][36][37] pollutant dispersion, 38,39 and subsurface exchange. 40 They have achieved significant insights into these processes. 21,41 However, aforementioned studies have not considered the scenario of submerged vegetation in wind-driven flows. ...

Hyporheic exchange driven by emergent vegetation patches: Experiment and simulations
  • Citing Article
  • November 2023

Journal of Hydrology

... The eddy covariance method is used to measure vertical wind speed and GHG concentration in turbulent atmospheric boundary layers (Kumar et al., 2023). Sediment respiration dynamics assessment evaluates the contributions of sediments to carbon emissions through in-situ measurements and the virtual incubator method (Gao et al., 2024;Yang et al., 2022). Modeling approaches, such as the GRAT and G-res tools, are utilized to predict long-term GHG emissions (Kumar et al., 2023). ...

Sediment respiration dynamics and its contribution to carbon emissions in stratified reservoirs
  • Citing Article
  • November 2023

Journal of Environmental Management

... This special issue is to present readers a collection of interdisciplinary approaches for lake water quality research. In total, 7 papers are published in this special issue, including the monitoring and modeling of total suspended solids (Chen et al., 2023), multi-approach framework to estimate the mass flux at the sediment-water interface (Sun et al., 2023), modeling of lake water temperature, biogeochemical processes and water quality (Zhu et al., 2023;Duc Dang et al., 2023;Tan et al., 2023;Bermarija et al., 2023), and impact of climate change on lake water level . Multiple modeling techniques have been presented in this special issue, including machine learning based approaches Tan et al., 2023), process-based models (Sun et al., 2023;Duc Dang et al., 2023;Bermarija et al., 2023), and simple statistical models (Zhu et al., 2023;Huang et al., 2023). ...

Multi-approach framework to estimate the mass flux at the sediment-water interface based on the effective diffusivity coefficient: A case study of the largest lake in North China
  • Citing Article
  • August 2023

Journal of Hydrology Regional Studies

... These prevailing environmental conditions, in addition to decreased flow rate, lowers oxygen replenishment by cutting lowering dissolution of atmospheric oxygen (e.g. Yu et al 2023). Other factors such as increased land use along the basin for agricultural activities and mining contribute to higher SPM and low DO (Fitri et al 2020). ...

Stagnant water environmental management in urban river networks: An integrated risk analysis involving hydraulic potential dissipation
  • Citing Article
  • May 2023

Journal of Hydrology

... Lucˇin et al. 19 employed numerical simulation to explore the impact of different cross-sections on the head loss, and the design of the trash rack was optimized to reduce the head loss. Zhu et al. 20,21 used numerical simulation of the velocity field inside the discharge passage to explain the large fluctuation velocity and high turbulence intensity at the trash rack section. ...

Experimental investigation on the unsteady flow fluctuation of a vertical pipe inlet/outlet of the pumped storage power station
  • Citing Article
  • February 2023

Journal of Energy Storage

... Lucˇin et al. 19 employed numerical simulation to explore the impact of different cross-sections on the head loss, and the design of the trash rack was optimized to reduce the head loss. Zhu et al. 20,21 used numerical simulation of the velocity field inside the discharge passage to explain the large fluctuation velocity and high turbulence intensity at the trash rack section. ...

Numerical and experimental assessment of the water discharge segment in a pumped-storage power station
  • Citing Article
  • December 2022

Energy

... However, the inhomogeneity of the sediment layer causes an increase in HE flux, even up to an order of magnitude (Pryshlak et al., 2015;Salehin et al., 2004;Zhou et al., 2014). Moreover, HE flux increases with an increase in the permeability of the sediment layer (Lv et al., 2022). This means that HE flux due to vegetation patches obtained from this prediction model is only applicable to vegetation patch flow scenarios with similar sediment layer characteristics to those of this study. ...

Numerical simulation of hyporheic exchange driven by an emergent vegetation patch

Hydrological Processes

... Littering, decline and death are the necessary life stages of submerged plants. During the decomposition process of submerged plants residues, the contained nutrients are released into water bodies under the effects of physical leaching, microbial degradation, and mechanical crushing [7,8]. Previous studies mainly focused on the effects of decomposition process on the physical and chemical properties of water quality, and the migration of nutrient elements between water body and sediment. ...

Quantifying the effects of submerged aquatic vegetation on internal loading in lake: A modeling study of the largest shallow lake in North China
  • Citing Article
  • September 2022

The Science of The Total Environment