Ecohydrology最新文献

Photovoltaic (PV) power generation has attracted significant attention not only for its substantial carbon reduction potential but also as an emerging research focus regarding its ecological impacts, particularly in arid and semi-arid regions. The extensive construction of utility-scale PV plants on the desert areas alters near-surface microclimates, exerting non-negligible influences on ecosystems. While utility-scale PV plants significantly alter near-surface microclimates, traditional models often fail to capture the intricate feedback mechanisms between PV panels and the underlying surface. To address this gap, this study developed a novel ecohydrological model that explicitly integrates a physically-based PV canopy module into an existing ecohydrological model. Unlike conventional approaches, this model treats PV panels as a distinct canopy layer, allowing for the simultaneous resolution of energy and hydrological fluxes across the panel, vegetation and soil interfaces. Validated at the Kubuqi PV power plant, located in the arid region of Northern China, the model demonstrated satisfactory performance. Results reveal significant ecological benefits at the Kubuqi PV power plant: gross primary productivity (GPP) increased by 110 gC·m⁻² during the growing season compared to the natural scenario, accompanied by a carbon sink enhancement of 58 gC·m⁻². This improvement is primarily attributed to a marked increase in water-use efficiency (rising from 0.55 gC·m⁻²·mm⁻¹ in the natural scenario to 1.12 gC·m⁻²·mm⁻¹ in the PV scenario). Crucially, while the inter-panel areas functioned as a net annual carbon sink, areas directly under the panels acted as a carbon source. Although vegetation growth under the panels was suppressed by hydrothermal constraints, it exhibited higher water-use efficiency, indicating enhanced resource utilization under limiting conditions. This research advances the understanding of PV effects on ecohydrological processes in arid and semi-arid areas and establishes a novel modelling framework integrating PV canopy influences for arid ecosystems.

Urban rivers are subject to intense anthropogenic disturbances, with insufficient allocation of ecological water resources leading to impaired hydrological circulation, diminished self-purification capacity, severe degradation of biological communities and significant functional deterioration. This study investigates a quantitative methodology for determining the ecological and environmental water requirement threshold of urban rivers based on river health assessment. Acknowledging the complex, open, dynamic, coupled and nonlinear characteristics of river ecosystems, a system dynamics-variable fuzzy set coupled model was developed by integrating variable fuzzy set evaluation with system dynamics principles. This model establishes a response relationship between the river health index and ecological flow, enabling dynamic simulation of river health conditions under different hydrological regimes. Utilizing the unknown inflection point threshold determination method, ecological and environmental water requirement thresholds were quantified to maintain basic ecosystem stability and ensure the normal functioning of river ecosystem services. The proposed framework provides theoretical support for the scientific management of urban river systems.

When influenced by flood pulses, the ecosystems in rivers and floodplain wetlands become highly dynamic, with biological communities such as waterbirds and fish developing dependencies on surrounding water depth and flow velocity. However, current studies primarily focus on macroscale qualitative analyses and do not address the complex relationship between flood pulses and habitats. This paper examines lateral hydrologic connectivity and habitat changes in floodplain wetland systems resulting from flood pulses, utilizing a geostatistical connectivity function joined with a two-dimensional hydrodynamic model. This method enhances the quantitative accuracy and spatiotemporal dynamic characterization capabilities of hydrological connectivity, filling a research gap in the study of dynamic mechanisms and complex system modelling related to hydrological connectivity. The results reveal (1) overall connectivity (TC), general connectivity (GC) and the effective connectivity (EC) increase with the decrease of flood frequency. Among them, the dynamic change of EC is most significant. (2) Complex hydrodynamic changes induced by different types of flood pulses can result in nonlinear alterations in the lateral hydrologic connectivity of floodplain wetlands. That is, there are phase differences in the growth rate of lateral hydrologic connectivity. (3) Overall, waterbirds are fit to survive under low flood pulse conditions (50% ≤ P ≤ 100%). Fish and phytoplankton can survive under high flood pulse conditions (1% ≤ P < 2%). Benthos are adapted to survive in moderate flood pulse conditions (10% ≤ P < 20%). Moreover, sediment suspension is more likely to occur in high flood pulse conditions. These findings contribute to the restoration of wetland ecosystems and the improvement of riverine hydrological connectivity.

Human-induced pressures and global climate change are increasingly degrading freshwater resources worldwide. Continuous monitoring of these systems is therefore essential for assessing their ecological health. In this study, species–stressor relationships and ecological status were evaluated across seven lakes in the Antalya River Basin using phytoplankton-based indices and multimetric approaches. Canonical correspondence analysis identified key environmental drivers of phytoplankton distribution, including electrical conductivity (EC), total organic carbon (TOC), total suspended solids (TSS), pH, and dissolved oxygen (DO). These variables together explained 94.5% of the variation in species–environment relationships. Among the studied lakes, Lake Kırkgöz exhibited the highest water temperature (19.8°C) and EC (574 μS cm⁻¹), whereas Lake Eğri had the lowest temperature (14.7°C) and Lake Küllü the lowest EC (73 μS cm⁻¹). Elevated TOC concentrations were mainly observed in high-altitude lakes, particularly Lake Küllü, while moderate-altitude lakes such as Eğirdir and Gölcük showed higher DO levels. Phytoplankton community composition varied significantly among lakes, resulting in different trophic states. Based on total phosphorus, total nitrogen, Secchi depth, and chlorophyll-a, Lake Eğri was classified as oligotrophic, Lake Eğirdir as mesotrophic, and the remaining lakes as eutrophic. The Modified Phytoplankton Trophic Index (MPTI) showed a strong relationship with log-transformed total phosphorus (R² = 0.89), indicating good ecological status for Lake İlvat, poor status for Lake Kırkgöz, and moderate status for the remaining lakes. Multimetric biological (BCG) and chemical (ABOZ) assessments supported these patterns, identifying Lake Kırkgöz as the most degraded system and Lake İlvat as having the highest ecological status. Overall, this study highlights the importance of integrated multimetric approaches that combine biological and physicochemical indicators for robust assessment of lakes' ecological status.

Accurate prediction of drag coefficient (C_D) and terminal settling velocity for irregular, bio-origin particles is essential for dispersal assessment and eco-hydraulic simulation; however, substantial uncertainty persists for living Oncomelania hupensis because its conical–spiral shell, surface roughness and heterogeneous mass distribution are not adequately represented by classical spherical or generic non-spherical correlations. We quantified the settling of living O. hupensis collected from representative middle-Yangtze habitats, obtaining 70 valid individuals and stratifying them into three size classes by major-axis length. Tests were conducted in a transparent cylindrical column with a mid-column observation window. Terminal settling segments were objectively delineated from the near-zero-acceleration intervals of vertical displacement–time records, enabling the back-calculation of C_D and particle Reynolds number (R_e) via force–balance inversion. Measured terminal velocities spanned 7.08–15.324 cm/s, with corresponding C_D ranging 0.52–2.97 over R_e = 0.5–15. Building on the two-term Haider–Levenspiel structure, a morphology-aware drag correlation was developed in which model coefficients were parameterized as functions of shape descriptors (e.g., sphericity and Corey shape factor), supplemented by a smoothness-stabilized correction and a nonlinear morphology–drag coupling term, and it was calibrated using constrained nonlinear least squares with multi-start initialization. Relative to baseline spherical and commonly used non-spherical formulas applied to the same dataset, the proposed correlation increased the coefficient of determination from 0.45 to 0.76 and reduced mean square error from 0.23 to 0.11. Size-resolved results indicated the tightest C_D–R_e distributions for medium individuals, whereas small and large classes exhibited higher dispersion, consistent with posture/orientation variability and morphological heterogeneity. The resulting correlation and reproducible parameter-inference workflow provide practically accurate inputs for particle-tracking modules, improving predictions of settling distance, residence time and deposition hot spots of O. hupensis to support habitat management and schistosomiasis control strategies in river–floodplain systems.

The soil nutrient status in riparian zones, which are transitional areas between aquatic and terrestrial ecosystems, is highly dynamic and plays a crucial role in the health of aquatic ecosystems. However, the mechanisms underlying nutrient changes in these zones remain unclear and vary across studies. This study employed spatial distribution analysis, linear regression, Pearson's correlation, redundancy analysis (RDA), random forest analysis and partial least squares path modelling analysis (PLS–PM) to investigate the horizontal and vertical variations in soil nitrogen and phosphorus, as well as the regulatory roles of topography, hydrology and plants in soil nutrient changes in the riparian zones of Dongjiang Lake. The results showed clear stratification of soil nutrients, with nitrogen and phosphorus concentrations in the 0–20-cm soil layer generally higher than those in the 20–40-cm soil layer. Random forest analysis indicated that the key factors influencing nitrogen were flooding duration, flooding height and the digital elevation model (DEM), while phosphorus was mainly affected by plant factors (Shannon–Wiener index, Simpson index, density, coverage and biomass), distance from the mountain to plots, DEM and flooding duration. PLS–PM analysis revealed that soil nitrogen and phosphorus were shaped not only by the direct effects of topography, hydrology and plants but also by the indirect effects of hydrology mediated by topography. Furthermore, soil nitrogen in riparian zones was co-regulated by plant and hydrological factors, whereas soil phosphorus was co-regulated by topographic and plant factors. Compared with nitrogen, phosphorus exhibited greater instability. This mechanistic understanding of soil nutrient dynamics provides a scientific basis for nutrient control, management and ecological restoration in riparian zones.