Downstream Section Research Articles

Macroinvertebrates as a Bioindicator of Water Quality in the Jangkok River, Lombok Island

Rivers are water bodies in open ecosystems where activities in the environment have an impact on river water quality. Monitoring of water quality is necessary to preserve aquatic resources. One of the river basins on Lombok Island is the Jangkok River. This river has a high utility, so water quality monitoring is needed. Macroinvertebrates are one of the best biological indicators for water quality monitoring. The objective of this study is to determine the diversity of macroinvertebrates and the quality of Jangkok River waters by using macroinvertebrates as bioindicators so that the results of this study can be used as a reference basis for the future use of Jangkok River water in the allocation of community needs. The method used in this research is biomonitoring with macroinvertebrate bioindicators, and the technique used in sampling is purposive sampling. Sampling was conducted at three stations, namely the upstream, middle, and downstream parts of the Jangkok River. The data analysis used was the Family Biotic Index (FBI) supported by physical-chemical parameters. The results of this study showed that the macroinvertebrates identified were 721 individuals consisting of 5 classes, 17 orders, and 36 families. The water quality of the Jangkok River, based on the FBI value in the upstream and middle sections, is still included in the good category, while in the downstream section, it falls into the very bad category.

Impact of wastewater treatment and drought in an Alpine region: a multidisciplinary case study

In the context of global climate change, drought occurrence in streams of alpine origin is a recent phenomenon, whose impact is still poorly investigated. In this study, we adopted a three-disciplinary approach to investigate the response of an Alpine river (NW Italy) to severe drought conditions occurred in the year 2022. We hypothesised that the considerable loss in the water flow could exacerbate wastewater treatment plant (WWTP) discharge effects, lowering dilution capacity of the stream system and then increasing chemical/microbial pollution and altering benthic community characteristics. To assess river response to drought conditions of the considered year, the concentration of the main chemical variables, faecal indicator bacteria, pathogen presence and structural/functional organisation of benthic macroinvertebrates and diatom communities were measured monthly in the reaches located upstream and downstream of a WWTP (January–December 2022). Main environmental variables, such as flow velocity, water depth, and flow regime, were also considered. A multivariate analysis approach was then applied to emphasise correlations between selected variables and flow regime.Comparing upstream and downstream sections over the considered year, a common behaviour of chemical/microbiological parameters was observed, with generally higher concentrations of nutrients and bacterial indicators downstream of the local WWTP. Moreover, a positive correlation between water scarcity and nutrients/bacterial concentrations was revealed. The macroinvertebrate communities responded accordingly, both in terms of density and biological metric shift.Interestingly, differences between the two sections were strictly associated with hydrological conditions, with higher dissimilarities found in low-flow conditions. As the magnitude and duration of drought events are projected to increase in the years to come in different parts of Europe, this work can serve as a first building block and as a hint for future studies aimed at improving our knowledge about the consequences of these events that is pivotal for planning effective management strategies.

Kualitas Air dan Karakteristik Tanah Penduga Erodibilitas pada Sub-Sub DAS Amandit Kabupaten Hulu Sungai Selatan

Land management in, Amandit sub-sub watershed must comply with the principles of soil and water conservation to avoid erosion and sedimentation. The aim of this research was to assess water quality and soil characteristics that predict erosion in the upstream, middle and downstream areas. The purposive sampling method was used by taking soil and water samples in the upstream, middle and downstream parts. In the upstream section soil samples were taken with a slope of 15-25%, in the middle section with a slope of 8-15% and in the downstream section with a slope of 0-8%. Soil samples were taken at each of six points representing the upstream, middle, and downstream parts of the area. Water sampling was carried out in the soil sampling area by paying attention to the slope of the land. The results showed that the water quality (pH, DHL, SAR, and TSS) in the area was in accordance with the quality of water for irrigation. Soil erodibility values in the upper and middle areas did not show significant differences. In the upstream part, soil erodibility had very low criteria and the middle part had low criteria but were different from the downstream area (medium criteria).

Qualitative and quantitative water investigation of Erin-Ijesha (Olumirin) Waterfall, Erin-Ijesha, Nigeria

This study focused on the assessment of water quality in Erin-Ijesha (Olumirin) Waterfall, a prominent natural attraction in southwestern Nigeria. The physiochemical parameters, heavy metal concentrations, and bacteriological characteristics were examined in the upstream, midstream, and downstream sections, to ensure the resource quality and safety from harm. The results revealed notable variations in water quality. The pH, Total Dissolved Solids, Electrical Conductivity, and Temperature were highest in the midstream while Total Hardness, Alkalinity, salinity, Chloride, sulphate, Phosphate, Nitrate, Calcium, and Magnesium were highest in the downstream section. The physicochemical parameters were within the acceptable limits of World Health Organization (WHO), United States Environmental Protection Agency (USEPA), and the Standard Organization of Nigeria (SON) standards, except the pH, temperature, and Total Hardness were higher than the acceptable limits of 6.5–8.5, <25 °C or >50 °C and 50 mg/L in all the sections. Iron was above the WHO, USEPA, and SON permissible limits of 3.0 mg/L in all the sections of the river while there was no indication of copper, lead, and cadmium. Bacterial contamination, particularly the presence of E. coli, exceeded recommended safety thresholds. The Total Bacterial Count (TBC) exceeded safety limits by 0.1 million cfu/mL in the downstream. The mean of the parameters was higher in some instances, and sometimes lower than the values in the various sections of the river. A significant relationship existed between most physical, chemical, and bacteriological parameters at p < 0.01. The appraisal of water quality in Olumirin Waterfalls emphasizes the need for proactive measures to ensure water safety, preserve ecosystems, and promote responsible water resource management.

Spatial distribution of physicochemical parameters and drinking and irrigation water quality indices in the Jhelum River, Pakistan.

Sustainable management of river systems is a serious concern, requiring vigilant monitoring of water contamination levels that could potentially threaten the ecological community. This study focused on the evaluation of water quality in the Jhelum River (JR), Azad Jammu and Kashmir, and northern Punjab, Pakistan. To achieve this, 60 water samples were collected from various points within the JR Basin (JRB) and subjected to a comprehensive analysis of their physicochemical parameters. The study findings indicated that the concentrations of physicochemical parameters in the JRB water remained within safety thresholds for both drinking and irrigation water, as established by the World Health Organization and Pakistan Environmental Protection Agency. These physicochemical parameters refer to various chemical and physical characteristics of the water that can have implications for both human health (drinking water) and agricultural practices (irrigation water). The spatial variations throughout the river course distinguished between the upstream, midstream, and downstream sections. Specifically, the downstream section exhibited significantly higher values for physicochemical parameters and a broader range, highlighting a substantial decline in its quality. Significant disparities in mean values and ranges were evident, particularly in the case of nitrates and total dissolved solids, when the downstream section was compared with its upstream and midstream counterparts. These variations indicated a deteriorating downstream water quality profile, which is likely attributable to a combination of geological and anthropogenic influences. Despite the observed deterioration in the downstream water quality, this study underscores that the JRB within the upper Indus Basin remains safe and suitable for domestic and agricultural purposes. The JRB was evaluated for various irrigation water quality indices. The principal component analysis conducted in this study revealed distinct covariance patterns among water quality variables, with the first five components explaining approximately 79% of the total variance. Recommending the continued utilization of the JRB for irrigation, we advocate for the preservation and enhancement of water quality in the downstream regions.

Gradient of microstructural damage along the dentato-thalamo-cortical tract in Friedreich ataxia.

The dentato-thalamo-cortical tract (DTT) is the main cerebellar efferent pathway. Degeneration of the DTT is a core feature of Friedreich ataxia (FRDA). However, it remains unclear whether DTT disruption is spatially specific, with some segments being more impacted than others. This study aimed to investigate microstructural integrity along the DTT in FRDA using a profilometry diffusion MRI (dMRI) approach. MRI data from 45 individuals with FRDA (mean age: 33.2 ± 13.2, Male/Female: 26/19) and 37 healthy controls (mean age: 36.5 ± 12.7, Male/Female:18/19) were included in this cross-sectional multicenter study. A profilometry analysis was performed on dMRI data by first using tractography to define the DTT as the white matter pathway connecting the dentate nucleus to the contralateral motor cortex. The tract was then divided into 100 segments, and dMRI metrics of microstructural integrity (fractional anisotropy, mean diffusivity and radial diffusivity) at each segment were compared between groups. The process was replicated on the arcuate fasciculus for comparison. Across all diffusion metrics, the region of the DTT connecting the dentate nucleus and thalamus was more impacted in FRDA than downstream cerebral sections from the thalamus to the cortex. The arcuate fasciculus was minimally impacted. Our study further expands the current knowledge about brain involvement in FRDA, showing that microstructural abnormalities within the DTT are weighted to early segments of the tract (i.e., the superior cerebellar peduncle). These findings are consistent with the hypothesis of DTT undergoing anterograde degeneration arising from the dentate nuclei and progressing to the primary motor cortex.

Analysis of Physical Indicators on The Diversity of Water Microorganisms in The Batang Hari River, Metro

The diversity of aquatic microorganisms was an important component in aquatic ecosystems, because they play a crucial role in biogeochemical cycles and ecological balance. These microorganisms can reflect the condition of the aquatic evirontment and be an indicator of ecosystem health. On the other hand, the physiscal conditions of water such as temperature, pH, and brightness greatly influence the presence and activity of these microorganisms. This research used survey and consecutive sampling methods. Sampling was carried out at two stations, namely in the upstream section located in Sumber Sari village, South Metro Ditrict, Metro City and in the downstream section located in Banjarrejo Village, Batanghari District, East Lampung Regency. The results of research carried out on the Way Batnghari tributary obtained and average temperature value of 29,5ºC in the upstream section and average temperature value of 28,6ºC in the downstream section. In terms of brightness, the upstream section has a better brightness with a value of 25 cm compared to the downstream section which has a lower brightness of 20 cm. The pH value in the downstream section is 6,7 slightly more acidic than the upstream section which has a normal pH level of 7,2. The diversity index of microorganisms in the Way Batanghari Metro tributary obtained a diversity index of 1,24 in the medium category. This value shows that the Way Batanghari tributary is included in the moderatelly polluted category.

Effects of small rock check dams on channel bed, vegetation diversity, and soil properties 10 years after a severe wildfire in forest micro‐catchments of central eastern Spain

AbstractOne of the most common post‐fire management techniques is the construction of check dams in catchments. However, little research has explored how small check dams impact on bed profile, vegetation diversity and soil properties several years after their construction in Mediterranean ephemeral channels draining micro‐catchments burned by severe wildfires. To fill this gap, this study has evaluated the effects of rock check dams installed about 10 years ago in small catchments after a wildfire in Castilla La Mancha (Central Eastern Spain). The changes in channel morphology, plant diversity as well as a large dataset of soil properties have been analysed close to the check dams in comparison to burned but non‐regulated channels. Neither the channel slope nor bed sediment size significantly changed downstream and upstream of the structures in comparison to the non‐regulated channels. Thanks to the unexploited retention capacity, the studied control works are still able to store the mobilised sediments on occasion of the most intense floods. Higher species richness in both upstream and downstream sections (+64%) was detected, while the plant evenness was not altered compared to the non‐regulated channels. Regarding the soil properties, increases in organic matter (over 200%), nutrients (+72% for N and +152% for P) and some cations (+29% for Ca and +86% for Mg) were measured. Overall, the presence of the rock check dams in the burned micro‐catchments, although improving many key plant and soil characteristics, did not sharply change the hydrological, geomorphological and ecological conditions compared with those of the non‐regulated catchments.

Dynamic Analysis of Changes in Jambu Riverbed and Banks: Case Study Around Cikuya Bridge

Several cross-sections of the Jambu River, particularly around the Cikuya Bridge, have experienced bank collapse phenomena. This paper interprets the issues related to bank collapse and its impact on the flow capacity of the Jambu River, especially around the Cikuya Bridge. Morphological changes were simulated using a sediment transport model implemented in the Hydrologic Engineering Center's River Analysis System (HEC-RAS) 6.3.1, integrated with the ARS-USDA Bank Stability and Toe Erosion Model (BSTEM). The simulation results indicate that over a period of 10 years, the thalweg elevation (the lowest point of a riverbed) of the Jambu River around the Cikuya Bridge is predicted to experience deposition in 17 cross-sections and erosion in 15 cross-sections. The highest deposition occurs at the cross-section below the Cikuya Bridge, with a thalweg elevation change of 0.59 m. This warrants attention as the storage capacity of the cross-section decreases by 7% from the initial condition. Predictions indicate that bank collapse will occur in 7 cross-sections over the next 10 years. This is attributed to the steep slopes of silt and clay banks, exceeding 45 degrees, and the reduced safety factor of bank stability due to groundwater pressure influenced by river discharge fluctuations and tidal effects reaching the Jambu River. Bank collapse impacts the elevation change of the riverbed and adds load to the sediment transport model from the collapsing cross-sections to the downstream sections. Keywords: Jambu River, Cikuya Bridge, Cilacap, sediment transport, bank stability and toe erosion model

Telemac 2D Modeling of Pollutant Transport in the Medjerda River: Impact of Tamarix Vegetation, Bousselem, Tunisia

The aim of this study is to evaluate the impact of pollutant discharges from Bousselem WWTP in the Medjerda River (Tunisia). We chose to model the transport of a passive pollutant from the Bousselem WWTP using Telemac 2D model. The hydrodynamic model calibration was based on identifying the roughness coefficient derived from existing vegetation, mainly from the Tamarix type. Three scenarios of hydrocarbon dispersion representing potential accidents, with concentrations of 0.25, 10, and 50 kg/m3, were simulated. Three successive downstream sections were chosen to track concentration variability in space and over time. The final concentrations recorded (6 km from discharge point) are 500 μg/l, 12 μg/l, and 2.4 μg/l for scenarios of 50 kg/m3, 1 kg/m3, and 0.25 kg/m3, respectively. These values significantly exceed the international norm for drinking water, set at 1 μg/l, and so causing problems for drinking use. The obtained results serve to ensure environmental safety for hydraulic resources.

Floristic Inventory, Diversity, and Community Structure of the Riparian and Coastal Sand Dune Landscapes in the Lower Padsan River Basin, Laoag City, Ilocos Norte, Philippines

Padsan River basin, the largest river system in Laoag City, Ilocos Norte, encompasses two vital ecological landscapes: coastal sand dunes and riparian areas. Despite its ecological importance, the floristic diversity of these landscapes still needs to be better understood and documented. A vegetation assessment was conducted to characterize the composition, diversity, and community structure of plants in the lower Padsan River landscapes. Eighteen 10 m x 10 m nested quadrats were established across six sampling stations. The study recorded 82 species of vascular plants from 80 genera and 41 families. Fifty-two percent are introduced species, 48% are native species, and 27% are invasive species. The plant life forms are composed of trees (34 spp.), herbs (17 spp.), vines (13 spp.) and grasses (9 spp.). Fabaceae and poaceae were the most species-rich plant families. Prosopis juliflora (Candaroma) was the most dominant tree species, comprising 29% of the entire population. The lower Padsan River basin landscapes exhibits moderate tree diversity (H’ = 2.7), with Shannon diversity indices ranging from 0.89 to 2.43 across sampling locations. The riparian areas showed higher tree Shannon diversity, richness, and evenness, while the coastal sand dune areas had higher tree dominance but lower Shannon diversity. The plant community structure varies between the two types of ecological landscapes (ANOSIM Global R=0.7, p&lt;0.05). P. juliflora dominates the coastal sand dune, while a mix of the Leucaena-Pithecellobium-Terminalia community characterizes the riparian area. This study provides essential baseline information on the floristic diversity and community structure, serving as a foundation for developing an integrated river management plan and strategies for conserving important ecological landscapes in the downstream section of the Padsan River Basin.

The deglacial history of 79N glacier and the Northeast Greenland Ice Stream

The Northeast Greenland Ice Stream (NEGIS) is the main artery for ice discharge from the northeast sector of the Greenland Ice Sheet (GrIS) to the North Atlantic. Understanding the past, present and future stability of the NEGIS with respect to atmospheric and oceanic forcing is of global importance as it drains around 17% of the GrIS and has a sea-level equivalent of 1.6 m. This paper reconstructs the deglacial and Holocene history of Nioghalvfjerdsbræ (or 79N Glacier); a major outlet of the NEGIS.At high elevation (>900 m asl) autochthonous blockfield, a lack of glacially moulded bedrock and pre LGM exposure ages point to a complex exposure/burial history extending back over half a million years. However, post Marine Isotope Stage 12, enhanced glacial erosion led to fjord incision and plateaux abandonment. Between 900 and 600 m asl the terrain is largely unmodified by glacial scour but post LGM erratics indicate the advection of cold-based ice through the fjord. In contrast, below ∼600 m asl Nioghalvfjerdsfjorden exhibits a geomorphological signal indicative of a warm-based ice stream operating during the last glacial cycle. Dated ice marginal landforms and terrain along the fjord walls show initial thinning rates were slow between ∼23 and 10 ka, but post-10 ka it is evident that Nioghalvfjerdsfjorden deglaciated extremely quickly with complete fjord deglaciation below ∼500 m asl between 10.0 and 8.5 ka.Both increasing air and ocean temperatures were pivotal in driving surface lowering and submarine melt during deglaciation, but the final withdrawal of ice through Nioghalvfjerdsfjorden was facilitated by the action of marine ice sheet instability. Our estimates show that thinning and retreat rates reached a maximum of 5.29 ma−1 and 613 ma−1, respectively, as the ice margin withdrew westwards. This would place the Early Holocene disintegration of this outlet of the NEGIS at the upper bounds of contemporary thinning and retreat rates seen both in Greenland and Antarctica. Combined with recent evidence of ice stream shutdown during the Holocene, as well as predictions of changing ice flow dynamics within downstream sections of the NEGIS catchment, this suggests that significant re-organisation of the terminal zone of the ice stream is imminent over the next century.

Longitudinal effects of land-cover transitions on the periphyton community of a tropical stream

Our study aims to investigate the longitudinal effects of two land-cover transitions on the periphytic algal community. We utilized datasets from three different studies conducted over a 5-year interval in a tropical headwater stream. The studied stream traverses two abrupt adjacent transitions from an upstream forest to a pasture and back to a downstream forest remnant. We performed a high-spatial resolution sampling and used generalized additive models (GAMs) to capture the non-linear gradient response of algal metrics to distance from land-cover transitions. Algal biomass presented a lagged response to increased light availability along the pasture section and decreased along a shorter distance in the downstream forest. Most algal metrics presented a lagged response to transitions, with chlorophyll-a taking up to 375 m to reach the maximum values inside the pasture and up to 300 m to return to reference conditions inside the downstream forest. In the downstream forested section, diatom richness and abundance were similar to the upstream forested section but did not return to reference conditions. The results were consistent across years. Our results indicate that, while riparian forest remnants can play an important role in buffering impacts related to land-cover changes in low order streams, both the magnitude and directionality of these effects might be influenced by longitudinal effects caused by the flow of water. Riparian forest remnants can have a longitudinal effect in stream conditions, influencing environmental characteristics even over non-forested reaches, to where the forest conditions can be propagated downstream by the flow of water.

Evaluation of the Lateral Connectivity of the Suncheon’s Dong Stream Based on Riverside Data

The lateral connectivity of Suncheon’s Dong stream was evaluated based on landside, waterside, and levee data of the river. A total of six items was evaluated, crosssectional structure, vegetation cover ratio, connecting waterway gate, levee slopes, urbanized area ratio and wetland area ratio. Among the items, the connectivity was high in the following order: cross-sectional structure, urbanization area ratio, and levee slope. In a total of 16 survey areas of Suncheon’s Dong stream, one, 12, and three areas were evaluated as continuity, damaged, and discontinuity respectively. The downstream section was evaluated as one continuity and three damaged, the lower-middle stream section was evaluated as one damaged and three discontinuity, and the upper-middle stream and upstream sections were evaluated as eight damaged. The cross-sectional structure, vegetation cover ratio, levee slope, and urbanized area ratio had low lateral connectivity in the lower-middle stream survey section, while the wetland area ratio had high lateral connectivity in the downstream survey section. The lateral connectivity evaluation results of the river aquatic ecosystem in Suncheon’s Dong stream can be used as basic data that is helpful in future ecological river management policies.

Mechanism analysis on heat transfer of supercritical LNG in horizontal U-bend tube

A comprehensive comprehension of the intricate heat transfer mechanisms pertaining to supercritical fluids within U-bend tubes holds paramount significance in the optimization design of submerged combustion vaporizers and other water-bath heating heat exchangers. This paper employs a combined approach of experimental analysis and numerical simulation to explore the complicated heat transfer processes of supercritical liquefied natural gas in the U-bend tube. For a careful consideration of similarity and safety, the N2–Ar mixture is used as the alternative experimental media. Upon validating the model's accuracy using experimental data, this study unveils the mechanism of the coupling effect between centrifugal force and buoyancy on heat transfer based on simulation results. The results show that the internal circulation flow field structure caused by centrifugal force weakens the heat transfer on the inner side within an angle range of approximately 60°. Along the entrance region of downstream straight tubing, secondary flow continues to be predominantly governed by centrifugal forces due to inertia-driven effects. Subsequently, buoyancy-driven secondary flow impels compression upon centrifugally-induced secondary flow towards the inner side, thereby instigating significant augmentation in fluidic heat transfer resistance in both the viscous sub-layer and buffer layer of the inner side. Overall, the downstream straight tube section exhibits a special heat transfer variation pattern characterized by an initial strengthening, followed by deterioration, and ultimately recovery due to the influence of centrifugal force, with a maximum influence distance extending to 175.5d.

Analysis of driving behavior in weak lane disciplined traffic at the merging and diverging sections using unmanned aerial vehicle data

The complexity of vehicular interactions at the merging and diverging sections is more severe due to the multiple decisions the driver has to make in a short time. The present study investigates and quantifies the driving behavior at the toll plaza’s merging and diverging sections. High-quality trajectory data for more than 7500 vehicle trajectories was derived from traffic video footage recorded by two Unmanned Aerial Vehicles (UAVs) operating concurrently upstream and downstream of the toll plaza. The data was extracted at 5 Hz, generating more than 5 million data points for the study. This approach facilitated a comprehensive and simultaneous capture of traffic dynamics. Various macroscopic and microscopic traffic parameters, like lateral and longitudinal speeds, following time, perception time, longitudinal standstill distance, and lateral clearance in the upstream and downstream sections, have been determined under weak lane disciplined traffic conditions. The mean speed in the merging section is 33.13 % lower than in the diverging section. Additionally, the average lateral speed in the merging section is 1.65 km/h, in contrast to 2.08 km/h in the diverging section, reflecting a 26 % increase. The lane changing and merging is prominent only up to 120 m to 140 m from the toll plaza in the merging section, and for diverging, 100 m to 200 m towards the toll plaza. The average following time in the diverging section is 5.7 s; for the merging section, it is 6.94 s, which is 13.86 % higher. The average perception time for the diverging section is 15.32 s; for the merging section, it is 13.13 s, which is 14.29 % lower. It has been observed that lateral clearance has a concave relationship with the speed in the merging section, whereas a convex relationship is in the diverging section due to the geometrical changes. The results presented in the study are expected to imitate heterogeneous traffic conditions observed in the field more realistically and will accelerate the understanding of behavioral aspects in complex interactive environments like that at merging and diverging sections of toll plazas.

Quali-quantitative water behaviour in an intensive swine production catchment in the Atlantic Forest biome, Southern Brazil.

Agriculture is an essential economic activity in Brazil. However, it is also the main source of water quality degradation. Monitoring catchments with agricultural land use is a way to generate information on a scale to identify causes and sources of water quality degradation. This work used monitoring data derived from hydrology and the quality of surface and underground water in an intensive agricultural catchment in the Atlantic Forest biome. The Fortaleza River catchment is located in the western part of Santa Catarina state in southern Brazil and has 62 km2 of drainage area. Hydrological and water quality monitoring was conducted for 7years at two fluviometric stations, three lysimeters, one meteorological station, and one piezometer. Data on precipitation, temperature, water flow, surface runoff, drainage, and water quality were used. Statistical analyses were also developed. Precipitation between 2013 and 2019 presented a homogeneous distribution in monthly and annual data, with January and July the months with the highest and lowest values, respectively. Statistical difference in the average and Q95 flows was found in upstream and downstream fluviometric sections. In terms of quality, statistical differences were identified for ammonium, nitrate, and potassium concentrations, which had higher concentrations in lysimeter runoff, indicating direct influence of agricultural activity on water quality. Principal component analysis (PCA) indicated that (i) surface water presented a positive relationship in Component 1 for the magnesium-calcium, sulphate-chloride, and acetate-bromide groups and a negative relationship for phosphate-nitrate; (ii) in lysimeters, the positive relationship occurred for Component 2 for the phosphate-chloride and sulphate-nitrate groups and was negative for ammonium-lithium and calcium-potassium-magnesium; and (iii) in piezometer, positive relationships were found for chloride-sodium and phosphate-nitrite pairs, while negative relationships were found for calcium-magnesium.

Enhancing Flow Batteries: Topology Optimization of Electrode Porosity and Shape Optimization of Cell Design

This research focuses on the improvement of porosity distribution within the electrode of an all‐vanadium redox flow battery (VRFB) and on optimizing novel cell designs. A half‐cell model, coupled with topology and shape optimization framework, is introduced. The multiobjective functional in both cases aims to minimize pressure drop while maximizing reaction rate within the cell. Topology optimization results reveal dependencies on initial value, porosity constraint, and flow rate. The distribution with lower porosity is preferred downstream of the inlet manifold. This design enhances active surface area, thus facilitating more effective conversion of incoming educts and improving mass transport of products. Compared to homogeneous electrodes, two‐part design demonstrates superior performance at specific porosity values. For combined porosities of 0.7 and 0.95, optimized distribution results in 81 % reduction in pressure drop, while conversion rate decreases by 7%. As regards various cell designs, optimization suggests a need to reconsider the vertical format of a rectangular cell. Horizontal cells are favored for nearly all porosities and flow rates. Trapezoidal and radial designs characterized by reduced downstream cross sections lead to higher pressure drops and are not preferred. This work provides further valuable insight into optimizing VRFB electrodes and challenges conventional cell design assumptions.

Evaluation of the Ecological Environment of the Fuhe River Based on the Diversity of Fish

This article takes the Fuhe River, which has water flowing into Baiyangdian all year round, as the research object. Through actual investigation and measurement of planktonic flora and fauna, benthic organisms, fish, and large vascular plants in the river, and based on fish diversity, the comprehensive evaluation index method is used to scientifically evaluate the ecological environment quality of the Fuhe River. The results showed that a total of 28 species of phytoplankton, 30 species of zooplankton, 11 species of benthic animals, 8 species of submerged plants, and 11 species of fish were detected in the survey area; From a diversity perspective, the diversity of the upstream and downstream river sections is higher than that of the downstream. Overall, the ecological environment quality of the Fuhe River in Baoding City ranges from medium to good, with good water quality in the upstream section and moderate water quality in the middle and downstream sections. This study provides a case study for the scientific evaluation of the ecological environment quality of the upper reaches of Baiyangdian.

Spatial pattern analysis reveals intra-specific competition and fractal characteristics of Pinus sylvestris var. mongolica populations in Xiaotaojia Gulley Watershed

The imprudent cultivation of Pinus sylvestris var. mongolica has led to degradation in the watersheds surrounding Chongli County. This study investigates the artificial forests of P. sylvestris var. mongolica in the Xiaotaojiagou watershed, Chongli County. Twenty-five subplots measuring 20 m × 20 m were established at upper, upper-middle, middle, and lower positions within the watershed. Spatial distribution patterns and fractal characteristics of P. sylvestris var. mongolica were analyzed using univariate pair correlation function g(r), marked correlation functions (marked correlation function Kmm(r), marked variation function γm(r), and Schlather’s Im(r) function), and fractal dimensions (box-counting dimension, information dimension). The findings are as follows: (1) P. sylvestris var. mongolica in the middle section of the watershed displayed the largest average diameters at breast height and tree height, while those in the lower section exhibited the largest average crown width. (2) P. sylvestris var. mongolica populations in the upstream, middle, and downstream sections of the watershed exhibited three alternating states: aggregated distribution, uniform distribution, and random distribution. However, with increasing spatial scale, the distribution gradually tended towards randomness. P. sylvestris var. mongolica in the upper-middle section of the watershed showed aggregated distribution at scales of 1.5–32.5 m, transitioning to random distribution and then to uniform distribution with increasing spatial scale. (3) Individual attributes of P. sylvestris var. mongolica (diameter at breast height, tree height, and crown width) exhibited high correlation and facilitation in the upstream and upper-middle sections at small-to-medium scales, whereas negative correlations and inhibitions were observed in the middle and lower sections. These attributes tended to be uncorrelated with increasing spatial scale. (4) Fractal dimensions indicated that the degree of aggregation of P. sylvestris var. mongolica population was lowest in the downstream section of the watershed. In conclusion, spatial distribution patterns and intraspecies relationships of P. sylvestris var. mongolica populations are influenced by spatial scale and environmental conditions, particularly in more resource-competitive downstream areas. Effective management and protection of P. sylvestris var. mongolica populations require targeted measures such as adjusting afforestation density, improving soil conditions, and implementing differentiated ecological restoration strategies to alleviate intraspecies competitive pressures and promote population health and sustainable development.