Variations In Discharge Research Articles

Differential training benefits and motor unit remodeling in wrist force precision tasks following high and low load blood flow restriction exercises under volume-matched conditions

BackgroundBlood flow restriction (BFR) resistance training has demonstrated efficacy in promoting strength gains beneficial for rehabilitation. Yet, the distinct functional advantages of BFR strength training using high-load and low-load protocols remain unclear. This study explored the behavioral and neurophysiological mechanisms that explain the differing effects after volume-matched high-load and low-load BFR training.MethodsTwenty-eight healthy participants were randomly assigned to the high-load blood flow restriction (BFR-HL, n = 14) and low-load blood flow restriction (BFR-LL, n = 14) groups. They underwent 3 weeks of BFR training for isometric wrist extension at intensities of 25% or 75% of maximal voluntary contraction (MVC) with matched training volume. Pre- and post-tests included MVC and trapezoidal force-tracking tests (0–75%–0% MVC) with multi-channel surface electromyography (EMG) from the extensor digitorum.ResultsThe BFR-HL group exhibited a greater strength gain than that of the BFR-LL group after training (BFR_HL: 26.96 ± 16.33% vs. BFR_LL: 11.16 ± 15.34%)(p = 0.020). However, only the BFR-LL group showed improvement in force steadiness for tracking performance in the post-test (p = 0.004), indicated by a smaller normalized change in force fluctuations compared to the BFR-HL group (p = 0.048). After training, the BFR-HL group activated motor units (MUs) with higher recruitment thresholds (p < 0.001) and longer inter-spike intervals (p = 0.002), contrary to the BFR-LL group, who activated MUs with lower recruitment thresholds (p < 0.001) and shorter inter-spike intervals (p < 0.001) during force-tracking. The discharge variability (p < 0.003) and common drive index (p < 0.002) of MUs were consistently reduced with training for the two groups.ConclusionsBFR-HL training led to greater strength gains, while BFR-LL training better improved force precision control due to activation of MUs with lower recruitment thresholds and higher discharge rates.

Reasons for Discharge in a National Network of Early Psychosis Intervention Programs.

Discharge from early psychosis intervention is a critical stage of treatment that may occur for a variety of reasons. This study characterizes reasons for discharge among participants in early psychosis intervention programs participating in the Early Psychosis Intervention Network (EPINET) which comprises >100 programs in the United Statesorganized under 8 academic hubs. We analyzed 1787 discharges, focusing on program completion, unilateral termination by the client/family, and lost contact with the client/family. We performed exploratory analyses of demographic, clinical, and functional predictors of discharge reason. Variables predictive of discharge type were included in multilevel logistic regressions, allowing for the estimation of predictors of discharge reason and variability in rates by program and hub. An estimated 20%-30% of enrolled patients completed the program. Program completion rates were higher among participants who were older on admission, had lower negative symptoms severity, spent more time in education, employment, or training, and who were covered by private insurance (a close proxy for socioeconomic status). Programs were more likely to lose contact with male participants, Black participants, and participants who were never covered by private insurance. After accounting for patient-level factors, there was substantial program-level variation in all 3 discharge outcomes, and hub-level variability in the proportion of participants who completed the program. The impact of race on program completion varied substantially by program. Participants were discharged from early psychosis intervention services for diverse reasons, some of which were associated with sociocultural factors. Disengagement is a widespread problem affecting all hubs.

Effects of tributary inflows on unsteady flow hysteresis and hydrodynamics in the mainstream

ABSTRACT Flooding propagation is a crucial aspect of hydrological monitoring and forecasting. Previous studies have focused on hysteresis in the rating curve, caused by energy loss during flood propagation. However, the impact of tributary inflow on hysteresis downstream remains unclear, leading to inconsistent field observations on whether it strengthens or weakens hysteresis. In this study, we conducted flume experiments to identify the relationship between hysteresis in unsteady flow and the discharge magnitude of the tributary and the unsteady flow period in the mainstream. It was found that the discharge variations in the tributary had a larger influence on hysteresis compared to the periodical variations in the mainstream unsteady flow. Interestingly, the hysteresis of the unsteady flow had an initial strengthening followed by weakening as the tributary discharge increased. When the tributary inflow was low, the widening of the downstream cross-section sharpened the flood wave, increasing the hysteresis. However, as the tributary discharge increased to generate a backwater effect on the mainstream, the pressure gradient flattened flood waves, thereby weakening the hysteresis. This study improves our understanding of how tributary inflow affects flood propagation in the mainstream, offering new insights for flood prediction and control.

Influence of large scale climate drivers on hydro-climate variability in Dwangwa River Basin, Malawi

Large-scale climate processes such as the Indian Ocean Dipole (IOD) have significant roles in modulating rainfall and hydrological systems. Understanding such processes can inform adaptation measures for climate change and variability, as well as water resource management and planning. This study investigated the impact of the Indian Ocean Dipole (IOD) on rainfall and discharge variability in the Dwangwa River Basin (DRB) in Malawi, a key inflow to Lake Malawi. Specifically, the study analysed annual rainfall variability trends from 1985 to 2015 using the Coefficient of Variation (CV) and the annual Precipitation Concentration Index (PCI). The significance and direction of rainfall and discharge trends were quantified using the Mann–Kendall trend test at α = 0.05 significance level. To evaluate the association between rainfall and IOD, the Pearson product moment used three IOD phases: positive, negative, and neutral. Simple linear regression was utilised to check the response of the river during the concerned IOD phases. The study found CVs between 20 and 30%, typical of climates with moderate monthly rainfall variability. The PCI ranged from 20 to 30%, suggesting a strongly seasonal and highly variable temporal intra-annual rainfall distribution in the DRB. Moreover, the Mann–Kendall test statistics showed insignificant decrease in annual rainfall trends. Further, the findings demonstrated an insignificant negative correlation between rainfall and positive IOD, with rainfall increases associated with negative IOD, whereas positive IOD is associated with decreased river discharge. Consequently, El Niño and a positive IOD could cause DRB to have low water availability. Therefore, the study demonstrates that rainfall is experiencing a decreasing trend, which is driven by large-scale mechanics.

An Investigation of Water Resource Management in the Beverage Industry

According to studies, industrial water use comprises production processes, auxiliary processes, kitchen use, and outdoor use. Reducing industrial water use is dependent on the implementation of administrative, engineering, mechanical, and human controls. The objectives of this research were to assess the water use of a Soft Drink Plant; determine the water use ratio for a two-year period; and determine the plant’s compliance with local and international regulations for wastewater discharge. We also determined the level of success of implementing a water minimisation plan, whether there was an improvement in the Water Use Ratio, and compliance of the industry with local and international discharge regulations. The sequential transformative strategy was used to collect and analyse data so as to ascertain water usage and disposal, and a semi-structured interview was conducted to validate the non-existence of heavy metals in the wastewater discharged from the soft drink plant. The Soft Drink Plant’s Water Minimisation Plan 2013-2016 achieved a high level of success overall, with 74.42% of the activities implemented by the assigned completion dates. However, three of the five measures implemented recorded low levels of success. Paired sample t-tests revealed statistically significant differences in the water use ratio obtained for the periods 2013-2014, 2014-2015, and 2013-2015, although the differences were relatively small (t (df)=2.242, p=0.047; t (df)=2.592, p=0.025; and t (df)=6.250, p=0.000) for the respective periods. Six of the eleven tested parameters were statistically different when compared to the Coca-Cola Operating Requirements and Environmental Protection Agency standards, indicating a high variation in effluent discharge.

Carcinogenic and non-carcinogenic health risks of heavy metals in windborne sediments from a residential area (Case study: Tabas, Iran)

Dust particles are considered as a very important way of soil contamination by heavy metals. Therefore, this study was conducted to evaluate the concentration of heavy metals and their health risk in windborne sediments. For this purpose, sediment traps were installed in five dominant wind directions including north, northeast, northwest, west, and southwest, and center of Tabas city (Iran) to collect the suspended sediments in the air. Sediment sampling was conducted monthly from January to December 2021. The concentrations of heavy metals were measured using atomic adsorption method followed by extraction by aqua regia, and the carcinogenic and non-carcinogenic health risks of heavy metals for children and adults were evaluated during different months of the year. According to the results, the maximum and minimum amounts of windborne sediments found in northwest (85.66 gm−2) and west (29.3 gm−2), respectively. Monthly variations in windborne sediments discharge also revealed that the maximum amounts of windborne sediments occurred in September and November 2021 from northeast (125 and 117 mgkg−1, respectively). The maximum concentrations of cadmium (0.82 mg/kg) were found in the west of Tabas, while those of lead (192.72 mg/kg), and nickel (227.34 mg/kg) were obtained in the city center. In addition, the highest carcinogenic and non-carcinogenic risks belonged to nickel and the lowest risks were obtained for lead. Also, the carcinogenic risk of cadmium was higher than lead but lower than nickel. In general, the carcinogenic and non-carcinogenic risks of the studied heavy metals were low (less than 1).

Has climate change over the last ten years caused a banalisation of diatom communities in Cypriot streams?

To unveil possible changes in diatom communities in Cypriot streams over the last ten years or so, we selected samples from the years 2020, 2021, and 2022 for the “recent” dataset (N = 119) and samples from the years 2010 and 2011 for the “historical” dataset (N = 108). Biotic homogenization has become a truly global phenomenon. Here we show that, over the last ten years, in response to increased water temperature, conductivity, and discharge variability due to climate-change, Cypriot stream diatom communities include a higher number of trivial (= widespread, tolerant, and opportunistic), aerial, and thermophilic species, have reduced β-diversity and increased nestedness. Moreover, IndVal analysis shows that indicator species from the historical dataset were characteristic, often relatively rare species, while the indicators of the recent dataset were a group of typical trivial, eutraphentic, and thermophilic species. As is almost always the case, the diatom communities we studied were subjected to multiple stressors, often affecting them in opposite ways. Besides the increase in trivial species, the reduction in β-diversity, and the rise in nestedness mentioned above, the diatom assemblages we studied also showed an increase in α-diversity that could be due to a moderate reduction in nutrients in several sites. High-ecological-integrity ecosystems, such as springs, waterfalls, and dripping rock-walls, in particular springs that were shown to be excellent hydrologic refugia in climates heavily affected by climate change, and the stream sites close to them should be carefully protected, as they can be refugia for sensitive and characteristic species that can recolonize the adjacent streams after adverse climatic events.

Freshwater input significantly reduces specific and functional diversity of small subarctic estuaries

Estuaries face mounting anthropic pressures. Climate change is projected to increase heavy precipitations, while agricultural and logging activities reduce land permeability, leading to more frequent flooding events that lower estuarine salinity. These hyposaline conditions pose physiological challenges for marine species, potentially reducing taxonomic diversity and biomass, and ultimately, ecosystem functions and services. Polar and subpolar estuaries, historically understudied, will undergo significant changes in freshwater discharge timing and variability due to predicted shifts from snow to rainfall regimes in these high latitudes. The investigation of biotic communities structure through functional traits is crucial for understanding biodiversity changes, evaluating ecosystem tolerance, and addressing the loss of function under stressful conditions. Therefore, our study aims to characterize the taxonomic and functional diversity of hard-substrate benthic communities along a salinity gradient in small subarctic estuaries. We hypothesize that communities closer to the riverine input will be less taxonomically diverse and abundant and with smaller individuals, leading to a loss of functions due to environmental filtering. To test our hypotheses, we measured traditional (biomass, taxonomic richness and diversity) and functional (functional richness and Rao's quadratic entropy) indices, as well as observed traits, of epibenthic hard-substrate macroalgae and macroinvertebrates along a four-level salinity gradient found in five small subarctic estuaries in Quebec (Canada). As predicted, freshwater inputs induced a decrease in biomass, taxonomic richness, functional richness, and Rao's quadratic entropy, with a fivefold reduction in total biomass of the epibenthic community from marine to low salinity zones. Freshwater inputs significantly shaped both taxonomic and functional trait structures, as the proportion of suspension feeders and long-distance dispersers decreased with rising freshwater inputs. While there was no clear trend for the size-class structure of invertebrate taxa, macroalgae were smaller at low salinities. Estuarine communities in subarctic regions may be vulnerable to future alterations in flooding patterns caused by global change, potentially affecting key ecosystem services such as suspended matter filtration. Functional trait indices were found to be efficient and serve as a valuable complement to taxonomic measures in detecting community shifts along salinity gradients, highlighting their usefulness in developing effective conservation and management strategies.

DeepWaterFraction: A globally applicable, self-training deep learning approach for percent surface water area estimation from Landsat mission imagery

Surface water area estimation is essential for understanding global environmental dynamics, yet it presents significant challenges, particularly when dealing with small water bodies like ponds and narrow width rivers. Surface water areas for these small bodies are often inaccurately represented by existing methods due to the spatial resolution limitations in commonly used remote sensing images. This study introduces DeepWaterFraction (DWF), a deep learning approach, to estimate percent surface water area from Landsat mission imagery. DWF is trained with a self-training method, which creates training data by upscaling remote sensing images and water map labels to a lower resolution, enabling the creation of a large-scale, global coverage training dataset. DWF demonstrates superior accuracy in estimating areas for small water bodies compared to several existing methods for surface water area estimation, with a pixel-wise root mean squared error of 14.3 %. Specifically, it reduces error rates by 54.3 % for water bodies with a minimum area of 0.001 km2 and by 22.6 % for those with a minimum area of 0.01 km2. DWF’s application in global river discharge inversion is also explored, showcasing its capability to capture width variations in narrow rivers (<90 m) better than existing methods, and its robustness across environments including wetland, tree covers, and urban areas. Even for wider rivers (>150 m), DWF’s performance remains superior, as its ability to accurately quantify mixed water pixel areas effectively reflects discharge variations when the variation area is small. We find that self-training is an effective strategy for generating extensive global training datasets for water mapping, with a high upscaling factor being critical for ensuring label accuracy. This study presents a step forward in the accurate global mapping of water resources.

Global hydrological models continue to overestimate river discharge

Global hydrological models (GHMs) are widely used to assess the impact of climate change on streamflow, floods, and hydrological droughts. For the ‘model evaluation and impact attribution’ part of the current round of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a), modelling teams generated historical simulations based on observed climate and direct human forcings with updated model versions. Here we provide a comprehensive evaluation of daily and maximum annual discharge based on ISIMIP3a simulations from nine GHMs by comparing the simulations to observational data from 644 river gauge stations. We also assess low flows and the effects of different river routing schemes. We find that models can reproduce variability in daily and maximum annual discharge, but tend to overestimate both quantities, as well as low flows. Models perform better at stations in wetter areas and at lower elevations. Discharge routed with the river routing model CaMa-Flood can improve the performance of some models, but for others, variability is overestimated, leading to reduced model performance. This study indicates that areas for future model development include improving the simulation of processes in arid regions and cold dynamics at high elevations. We further suggest that studies attributing observed changes in discharge to historical climate change using the current model ensemble will be most meaningful in humid areas, at low elevations, and in places with a regular seasonal discharge as these are the regions where the underlying dynamics seem to be best represented.

Ship scheduling problem in an anchorage-to-quay channel with water discharge restrictions

The optimization of ship scheduling in water-land transshipment plays a crucial part in enhancing transportation efficiency and alleviating traffic congestion on inland waterways, particularly when the service capacity of locks is insufficient. This study focuses on the ship scheduling problem in an anchorage-to-quay channel, where the navigation of ships is influenced by the water discharge during flood seasons. A new mixed-integer linear programming (MILP) model is formulated for this problem, in which the interconnected decision of ships’ navigation and berthing activities, the variation of water discharge in the waterway channel, and the change of navigation scenarios (i.e., normal or flood impact) are explicitly taken into account. Then a multi-population genetic algorithm (MPGA) is applied to solve this model. Numerical experiments conducted for the Three Gorges Dam (TGD) demonstrated that the proposed heuristic method can tackle the ship scheduling problem within a reasonable time, which is also effective in assisting ships to match acceptable water discharge time window by slightly adjusting the departure time of ships at the anchorage or quay. Furthermore, the proposed method can ensure the navigational safety of ships and improve the efficiency of ship transportation in different scenarios, and quantitatively evaluate the water discharge impact.

Scour-depth variability controls channel-scale stratigraphy in experimental braided rivers

ABSTRACT Braided rivers distribute sediment across landscapes, often forming wide channel belts that are preserved in stratigraphy as coarse-grained deposits. Theoretical work has established quantitative links between the depth distribution of formative channels in a braided river and the geometry of their preserved strata. However, testing these predictive relationships between geomorphic process and stratigraphic product requires examining how braided rivers and their deposits coevolve, with high resolution in both space and time. Here, using a series of four runs of a physical experiment, we examine the controls of water discharge and slope on the resulting geometry of preserved deposits. Specifically, we focus on how a twofold variation in water discharge and initial riverbed slope affects the spatiotemporal distribution of channel depths and the geometry of preserved deposits of a braided river. We find that the channel depths in the laboratory experiment are described by a two-parameter gamma distribution and the deepest scours correspond to zones of erosion at channel-belt margins and channel-thread confluences in the channel belt. We use a reduced-complexity flow model to reconstruct flow depths, which were shallower compared to channel thalweg depths. Synthetic stratigraphy built from timeseries of topographic surfaces shows that the distribution of cut-and-fill-unit thickness is invariant across the experiments and is determined by the variability in scour depths. We show that the distribution of cut-and-fill-unit thickness can be used to reconstruct formative-channel-depth distributions and that the mean thickness of these units is 0.31 to 0.62 times the mean formative flow depth across all experiments. Our results suggest that variations in discharge and slope do not translate to measurable differences in preserved cut-and-fill-unit thickness, suggesting that changes in external forcings are likely to be preserved in braided river deposits only when they exceed a certain threshold of change.

Three-dimensional simulations of load rejection processes of a variable-speed pump-turbine under different initial rotational speeds

Abstract The load rejection transient process is one of the most dangerous operating conditions in pumped storage power stations. When the operating point slides through the S-shaped region quickly, the pressure fluctuations increase sharply and the unit vibrates obviously. In variable-speed units, the different initial rotational speeds have significant effects on the operating point trajectories during load rejection processes. In this paper, under the same head and guide vane opening, the load rejection processes with different initial rotational speeds were simulated by using three-dimensional methods, and the variations of rotational speed, discharge and torque were obtained and analyzed. The results show that the changes of initial rotational speeds affect the shapes of velocity triangle at the runner inlet and outlet, and causes the flow separations and vortices in the runner and draft tube, which leads to different efficiency and torque of the pump-turbine under initial steady conditions. In addition, during load rejection processes, the maximum values of macro parameters and pressure fluctuations, and the transitions of flow patterns have obvious differences because of these different initial rotational speeds.

Land-Use–Land Cover Changes in the Urban River’s Buffer Zone and Variability of Discharge, Water, and Sediment Quality—A Case of Urban Catchment of the Ngerengere River in Tanzania

The physical integrity of the Ngerengere River and its three tributaries drains within Morogoro Municipality were evaluated by assessing the variations in land-use–land cover (LULC) in the river’s buffer zone, the discharge, and the contamination of river water and sediment from nutrients and heavy metals. Integrated geospatial techniques were used to classify the LULC in the river’s buffer zone. In contrast, the velocity area method and monitoring data from the Wami-Ruvu Basin were used for the discharge measurements. Furthermore, atomic absorption spectrophotometry was used during the laboratory analysis to determine the level of nutrients and heavy metals in the water and river sediment across the 13 sampling locations. The LULC assessment in the river’s buffer during the sampling year of 2023 showed that bare land and built-up areas dominate the river’s buffer, with a coverage of 28% and 38% of the area distribution. The higher discharge across the sampling stations was in the upstream reaches at 3.73 m3/s and 2.36 m3/s at the confluences. The highest concentrations of heavy metals in the water for the dry and wet seasons were 0.09 ± 0.01, 0.25 ± 0.01, 0.03 ± 0.02, 0.73 ± 0.04, 4.07 ± 0.08, and 3.07 ± 0.04 mg/L, respectively, for Pb, Cr, Cd, Cu, Zn, and Ni. The order of magnitude of the heavy metal concentration in the sediments was Zn &gt; Ni &gt; Cr &gt; Cu &gt; Cd &gt; Pb, while the highest NO2−, NO3−, NH3, and PO43− in the water and sediment were 2.05 ± 0.01, 0.394 ± 0.527 0.66 ± 0.05, and 0.63 ± 0.01 mg/L, and 2.64 ± 0.03, 0.63 ± 0.01, 2.36 ± 0.01, and 48.16 ± 0.01 mg/kg, respectively, across all sampling seasons. This study highlights the significant impact of urbanization on river integrity, revealing elevated levels of heavy metal contamination in both water and sediment, the variability of discharge, and alterations in the LULC in the rivers’ buffer. This study recommends the continuous monitoring of the river water quality and quantity of the urban rivers, and the overall land-use plans for conserving river ecosystems.

PENGARUH VARIASI TINGGI SUDU TURBIN DARI TINGGI BASIN TERHADAP DAYA DAN EFISIENSI TURBIN VORTEX

Electrical energy is a very important need for human life in various aspects, both on a large and small scale. One of the efforts to reduce the use of fossil fuels is to use natural resources that are not limited and can be renewed. Micro Hydro Power Plant (MHP) is an alternative source of electricity for the community, one of which is a vortex turbine. The vortex turbine is one type of micro hydro turbine that utilizes a whirlpool as a blade drive. This study examines the effect of blade height variations of 25%, 30%, and 35% of the basin height on power and efficiency. The results showed that the largest turbine power at 25% blade height variation from the basin height with a discharge of 0.009 m3/s was 3.294 Watt with an efficiency of 51.10%. The largest turbine power at an angle variation of 30% of the basin height with a discharge of 0.009 m3/s is 3.364 Watt with an efficiency of 50.66%. The largest turbine power at an angle variation of 35% of the basin height with a discharge of 0.009 m3/s is 4.062 Watt with an efficiency of 62.35%. Turbine power based on two-way anova analysis shows that between variations in turbine height and flow discharge have a significant effect on the turbine power produced and turbine efficiency based on two-way anova analysis shows that between variations in turbine height and flow discharge have a significant effect on the turbine efficiency produced.

Rotational and vibrational temperatures of transient atmospheric glow plasma

Plasma ignition can significantly improve the efficiency and performance of combustion devices through the enhancement of combustibility limits. Investigating plasma development for fundamental experimental flame conditions (i.e. spherical flame experiments) can provide insight into how plasma thermalizes the combustible mixture and, therefore a better understanding of flame development in future experimental studies. This study observed an ignition system designed to produce spherical flames in quiescent gas inside a constant-volume combustion chamber. Rotational and vibrational temperature measurements of dry atmospheric air glow plasma are reported. Measurements were taken for a transient discharge with currents less than 0.5 A. The electrode wire geometry and discharge variation resulted in an ellipsoid-shaped kernel and plasma region with an abnormal glow discharge. The measured temperatures were compared to the conductive thermal kernel boundary observed with Schlieren imaging. Maximum rotational and vibrational temperatures of 3000 K and 10 000 K, respectively, were observed near the anode electrode for a 0.5 A current. The temperature decreased with the axial distance from the anode, while a constant temperature was observed in the radial direction. Lower currents resulted in a smaller temperature, with minimum measured rotational and vibrational temperatures of 1500 K and 5000 K, respectively. The results were compared with available experimental literature and the variation observed was a result of the transient nature, which resulted in hysteresis in temperature vs discharge current measurements.

Effect of nutrient reductions on dissolved oxygen and pH: a case study of Narragansett bay

To assess the consequences of nutrient reduction strategies on water quality under climate change, we investigated the long-term dynamics of dissolved oxygen (DO) and pH in Narragansett Bay (NB), a warming urbanized estuary in Rhode Island, where nitrogen loads have declined due to extensive wastewater treatment plant upgrades. We use 15 years (January 2005-December 2019) of measurements from the Narragansett Bay Fixed Site Monitoring network. Nutrient-enhanced phytoplankton growth can increase DO in the upper water column while subsequent respiration can reduce water column DO and enhance bottom water acidification, and vice-versa. We observed significant decreases in surface DO levels, concurrent with a significant increase in bottom DO, associated with the nitrogen load reduction. Surface DO decline was primarily attributed to reduced intensity of primary productivity, supported by a concurrent decrease in surface chlorophyll concentrations. Meanwhile, the influence of reduced organic matter respiration led to the increase of bottom DO levels by 9 µmol kg-1 (approximately 0.2 mg L-1 for typical summer temperature and salinity) over a 15-year period, which overcame the opposite influence of oxygen reduction from solubility decreases due to warming temperatures. In contrast, long-term changes in surface pH have not exhibited discernible trends beyond natural variability, likely due to the complex and sometimes opposing influences of biological activity and changing river flow conditions. We observed a slight increase in bottom pH, associated with the increase in DO in bottom water. Notably, future variations in freshwater discharge, particularly linked to extreme precipitation events, may further influence water carbonate chemistry and thereby impact pH dynamics. This study highlights the necessity of long-term time series measurements in helping understand the impacts of environmental management practices in improving water quality in coastal regions during a changing climate.

Reach scale channel planform dynamics of transboundary River Jaldhaka within Himalayan Foreland Basin

ABSTRACT The slopes of Himalayan piedmont and foothill plain are being modified by the Himalayan origin river systems. In this study, spatiotemporal dynamics of channel planform of braided River Jaldhaka have been estimated using United States Army Map (1956) and landsat satellite images (1980-MSS, 1990-TM, 2000-TM, 2010-ETM+ and 2022-OLI) for the delineation of banklines, channel length, sinuosity index, braiding index, channel widths, identification of partial channel avulsion sites and bankline migration using Digital Shoreline Assessment System (DSAS) toolbar. Linear Regression Rate, Net Bankline Movement and End Point Rate were also calculated. Results revealed that the lower reach is more sinuous (maximum average channel sinuosity 1.65) compared with reach-I (1.29) and II (1.11)). The maximum channel width was in the year 2022 (968.6 m) and minimum average channel width was in 1956 (239.87 m). The maximum BI value (3.55) has been calculated in the sub reach-2 (SR-2, reach-I). Similarly, DSAS output shows maximum average EPR values (6.43 m/year) in lower reach which was most erosion prone bank. Bank facies study showed that non-cohesive bank materials accelerate rapid rate of channel avulsion and bank erosion. The variation of discharge, velocity, presence of vegetation and anthropogenic interventions controls the nature of planform changes of Jaldhaka River.

Architecture and history of uranium-bearing Palaeocene–Eocene strata deposited on the eastern margin of the Peri-Tethys (Chu-Sarysu Basin, south Kazakhstan)

Deciphering the facies and architecture of alluvial successions provides invaluable insights into the interplay of tectonics, climate, eustasy, and autogenic processes affecting terrestrial sedimentary systems. The stratigraphic response of fluvial systems to variations in discharge and sediment-supply regimes is now well-understood and is tied to changes in climate, precipitation patterns, or sediment sources. The uraniferous Chu-Sarysu Basin in south Kazakhstan occupies the tectonically stable Turan Platform on the eastern margin of the Peri-Tethys, and the study of its Palaeocene–Eocene sedimentary fill offers an opportunity to unravel eustatic and climatic controls that drove the architecture of reservoirs hosting economically important deposits. The stratigraphic succession comprises two multistorey, laterally extensive, sheet-like sandstone bodies floored by prominent erosion surfaces and interpreted as the deposits of channel belts. These packages are interstratified with floodplain, coastal-wetland, and marine-embayment complexes reflecting major extra-channel belt avulsions and marginal-marine incursions on the low-gradient alluvial plain. The stratal architecture was controlled by changes in accommodation likely induced by well-documented sea-level changes in the Peri-Tethys during the Palaeogene, which permitted the development of a chronostratigraphic framework. Eustatic variations culminated in the widespread flooding of the Turan Platform in the middle Eocene, reflected by transgressive lags above a wave ravinement surface capping terrestrial and marginal-marine deposits. Marked changes in fluvial facies, floodplain styles, and inferred channel planforms between Palaeocene and Eocene strata suggest a climatic overprint on river discharge and sedimentation. Upper Palaeocene meandering channel deposits encased in well-drained floodplain strata are indicative of perennial discharge under a semi-arid climate, whereas lower Eocene low-sinuosity channel fills, displaying evidence for transcritical flows and abundant in-situ vegetation, point to intermittent runoff patterns consistent with a humid and seasonal climate. An evolution in atmospheric moisture at the Palaeocene–Eocene boundary from arid to humid conditions has been reported across the Tethys region, and linked to global climatic perturbations of the Palaeocene–Eocene Thermal Maximum.

Discharge variations of qanat near an ephemeral stream

Ephemeral streams are the most important sources of groundwater recharge in arid and semi-arid regions of the world. To extract this replenishable water, most of the time, qanats are constructed parallel to the ephemeral streams. Analytical modeling of a stream-qanat system can provide an effective tool for managing such a system in a timely fashion and, thus, is commonly applied in the hydrological communities. However, the available analytical solutions of discharge variation of qanat only consider the distributed recharge from rainfall and cannot be used to investigate the effects of geometric parameters of stream and hydraulic parameters of aquifer on the discharge of qanat near an ephemeral stream. Thus, the goal of this work is to obtain a semi-analytical solution of qanat discharge due to recharge from an ephemeral stream of an arbitrary shape in a three-dimensional anisotropic homogeneous unconfined aquifer. The solution is obtained via Laplace and Fourier transformations along with the principle of superposition. The results of this study are presented in the form of qanat discharge-time curves. The influences of the qanat length, shape, and recharge distribution along the ephemeral stream are explored in great detail. The effects of the hydraulic parameters of the aquifer on the discharge of qanat are also investigated. The results of this study can be used to predict the discharge of qanat due to recharge from an ephemeral stream, to calculate the optimum length of a qanat for maximum extraction of the replenished water, to estimate the adequate recharge from the ephemeral stream and the hydraulic parameters of aquifer using the discharge data of qanat, among other applications.