Upland River Research Articles

Self-purification in tropical upland rivers as affected by environmental factors: the case of Balili River in Benguet, Philippines

A major data gap in tropical river ecology is the limited documentation of natural water purification of upstream rivers. This study documented the improvement of water quality of downstream Balili River as affected by environmental factors and macrophyte diversity using a mixed-method approach (water quality assessment, plant inventory, field observation, canonical correspondence analysis, community interview). Results showed that the distance from pollution plays a significant role in the self-purification of the river while the floral diversity maintains the riparian from further contaminating the water and at the same time absorbing air pollutants. Generally, the pollution reduction and %change is exponential at 2 and 3 km from point source then taper at 4 and 5 km. At 3 km from the point source, 30% improvement in TDS, BOD and salinity, 25% for EC, 20% in TSS, 35% in WQI, 36% in CPI, and 50% for DO were noted. Key factors that influence the self-purification process in the river were distance from pollution source, elevation, human disturbance (as indicated by %tree canopy) and temperature. These findings highlight the importance of distance from pollution sources and floral diversity in driving water quality improvements, with implications for sustainable water resource management in tropical regions.

Factors Affecting Survival of Common Sandpiper (Actitis hypoleucos) Nests along the Semi-Natural Vistula River in Poland.

Predation is an important factor limiting bird populations and is usually the main factor influencing nest survival. In riverine habitats, flooding poses an additional significant challenge. Our study aimed to elucidate the influence of nest location and incubation timing on the survival of common sandpiper nests in a large, semi-natural, lowland river. The survey was carried out in central Poland on the Vistula River, in 2014-2015, 2021, and 2023, along two river sections 2 km and 10 km in length. The nest survival rate was 27%, which is twice as low as that reported on small upland rivers, with flooding being an additional factor causing losses on the Vistula River. Our research showed that mammalian and avian predation accounted for 51% of losses and flooding for 49% of losses. The negative impact of floods on nest survival decreased as the breeding season progressed between May and July, while the chances of being depredated increased during the same period. Nests placed under shrubs were less likely predated than nests located in grass. Moreover, locating the nest in proximity to water increased nesting survival and in fact, more nests found in our study were situated close to the water's edge.

Correction: The functional diversity of plants dispersed via three upland rivers in humid subtropical monsoon climate

Correction: The functional diversity of plants dispersed via three upland rivers in humid subtropical monsoon climate

The functional diversity of plants dispersed via three upland rivers in humid subtropical monsoon climate

The functional diversity of plants dispersed via three upland rivers in humid subtropical monsoon climate

Exploring invasiveness and versatility of used microhabitats of the globally invasive Gambusia holbrooki

Non-native species can lead to severe impacts on invaded ecosystems, including the decline of ecosystem function through deleterious impacts on species diversity. The successful establishment of non-native species in new environments is the first barrier a species must overcome, ultimately depending on its ability to either cope with or adapt to local site-specific conditions. Despite the widespread distribution and ecological consequences of many freshwater invaders, site-specific and climatic preferences are often unknown. This is also the case of the Eastern mosquitofish Gambusia holbrooki, a global invader considered as a pervasive threat to endemic species. Here, we determined the ecological features and preferred site-specific conditions of G. holbrooki in Türkiye, which spans a wide range of diverse biogeographically distinct ecosystems by surveying populations from 130 localities in 2016 and 2017. Gambusia holbrooki were detected by hand-net in 48 of these sites (19 lotic, 29 lentic). It showed a preference for shallow waters with medium sized rocks, and abundances differed spatially across a latitudinal gradient and was influenced predominantly by variations in pH. The only other factors predicting its presence were low current velocities and gravel substrate, highlighting its ecological versatility in utilising a wide range of microhabitats. Bioclimatic models suggest that G. holbrooki is found in areas with a wide average annual temperature ranging from 10 to 20 °C, but with temperature not being a limiting factor to its invasion. Gambusia holbrooki shows a preference for xeric freshwater ecosystems and endorheic basins, as well as temperate coastal rivers, temperate upland rivers, temperate floodplain rivers and wetlands, and tropical and subtropical coastal rivers. These results, particularly the wide occurrence with only few limiting factors, emphasise the invasion potential of mosquitofish and should substantiate the need for localised invasive species management and conservation efforts, particularly in smaller or insular areas where mosquitofish and endemic fish species co-exist.

Fluvial sediment load sensitivity to climate change in cold basins on the Tibetan Plateau: An elasticity approach and the spatial scale effect

The sensitivity of fluvial sediment load to climate change and predictions of future sediment load in cold basins remain poorly investigated, although changes in river sediment transport have important geomorphological, ecological, and societal implications. Here, we adapt a sediment elasticity approach to examine the sensitivity of fluvial suspended sediment load to changes in air temperature and precipitation in the headwater of the Yangtze River (HYR) on the inner Tibetan Plateau. Results show that every 1 °C increase in air temperature can increase the suspended sediment load by 14–27 % by intensifying thermally-driven glacial and permafrost erosional processes, and every 10 % increase in precipitation can increase the suspended sediment load by 16–24 % through enhancing pluvial-driven erosional processes. We predict an increase of 60–85 % in the suspended sediment loads in HYR by 2050 relative to the present-day period under the Representative Concentration Pathway 4.5, as both air temperature and precipitation are projected to increase. Our analysis highlights that smaller upland rivers appear to respond to modern climate change more rapidly and intensively than larger downstream rivers due to the larger glacier and permafrost coverages, poorer vegetation, as well as steeper fluvial relief, and higher sediment connectivity. This study provides a framework and a data-driven sediment elasticity approach to predict climate change and cryosphere degradation-driven changes in future fluvial suspended sediment load in cold basins, highlights the importance of the spatial scale effects in modulating fluvial responses, and has implications for assessing the impacts of climate change on channel morphology and aquatic ecosystems.

A hybrid machine learning-based multi-DEM ensemble model of river cross-section extraction: Implications on streamflow routing

Accurate representation of river channel and floodplain geometries is of prime concern for streamflow routing and flood inundation modelling under inadequate surveyed river cross-section data-condition, in many rivers across the globe. Due to global coverage and easy accessibility, the public domain medium resolution (1-arc second) DEMs such as SRTM, ASTER, and ALOS-AW3D30, with a linear vertical bias-correction approach, are widely used for hydrodynamic modelling of upland river networks. In this context, this study, for the first time, developed a hybrid machine learning-based Multi-DEM Ensemble (MDE) approach to simulate bias-corrected cross-sections using open source DEMs-extracted river cross-sections. Additionally, the hydraulic suitability of the simulated cross-sections and associated uncertainties were analysed. For this, the routing of streamflow and water level was performed using MIKE11-HD for a low-gradient flood-prone deltaic river basin of Eastern India (∼9000 km2) consisting of 19 river distributary systems. A comprehensive evaluation of the developed hybrid machine learning-based MDE models revealed an excellent performance of the Random Forest-Particle Swarm Optimisation-MDE (RF-PSO-MDE) model (NSE: 0.89–0.95; RMSE: 1.75–2.23 m) and Deep Neural Network-Particle Swarm Optimisation-MDE (DNN-PSO-MDE) model (NSE: 0.89–0.93; RMSE: 2.09–2.27 m) followed by the Support Vector Machine-Particle Swarm Optimisation-MDE (SVM-PSO-MDE) model (NSE: 0.87–0.92 and RMSE: 2.22–2.50 m). The MIKE11-HD simulations using RF-PSO-MDE and DNN-PSO-MDE model-simulated cross-sections were in close agreement with the observed streamflow and water level hydrographs, together with excellent matching of the flood peak, time to flood peak, and streamflow regimes. Predictive uncertainties analysis by the quantile regression technique confirmed an acceptable range of the Mean Prediction Interval and Percentage Interval Coverage Probability for the MIKE11-HD-RFMDE and MIKE11-HD-DNNMDE model variants including the MIKE11-HD-S model. Conclusively, the developed MDE models have potential for generating river cross-sections under sparse bathymetric conditions for the accurate simulation of streamflow and water level estimates using public domain digital elevation models.

The occurrence and zoonotic potential of Cryptosporidium species in freshwater biota

BackgroundProtozoan pathogens from the genus Cryptosporidium cause the diarrhoeal disease cryptosporidiosis in humans and animals globally. Freshwater biota could act as potential reservoirs or zoonotic sources of Cryptosporidium infections for livestock and people, but Cryptosporidium occurrence in aquatic biota is largely unexplored. The aim of this study was to investigate the occurrence of Cryptosporidium in a range of freshwater organisms in upland rivers across England and Wales.MethodsFish were sampled by electrofishing, invertebrate larvae by kick sampling and the otter Lutra lutra and mink Mustela vison through faecal samples collected opportunistically as part of a nation-wide study. PCR targeting the small subunit ribosomal RNA gene was used to detect Cryptosporidium species.ResultsCryptosporidium occurred in just 0.8% of all the samples and in none of 73 samples from nine invertebrate genera. Cryptosporidium was detected in two of 2/74 fish samples (2.7%), both salmonids, and in 2/92 otter faecal samples (2.17%), but there were no positive samples in mink (0/24) or the bullhead Cottus gobio (0/16).ConclusionsLow detection rate of human-infective Cryptosporidium species in aquatic fauna indicates they may present a low risk of contamination of some upland freshwaters.Graphical

A global assessment of estuarine tidal response to sea level rise

Climate change induced sea level rise (SLR) is one of the greatest challenges threatening the sustainable management of estuaries worldwide. Current knowledge regarding SLR and estuarine hydrodynamics is primarily focused on individual case studies, which provides limited guidance on how different estuary typologies will respond to SLR. To expand the current knowledge, this research used an idealised hydrodynamic approach to analyse the tidal range dynamics of 25 real-world estuaries with diverse shapes and boundary conditions, providing insights into estuarine response to SLR-induced tidal variations. Under present-day conditions, short length estuaries with wide entrances, deep waters, strong convergence, macro-tidal conditions, low values of roughness, and low upland river inflows are likely to experience amplified tidal range patterns; whereas lengthy estuaries with narrow entrances, shallow water depths, micro/meso-tidal conditions, high values of roughness, and high upland river inflows often exhibit a mix of dampened-amplified or fully dampened tidal range patterns. Under the effects of SLR, estuarine tidal range dynamics change depending on their present-day tidal range patterns. Where the present-day tidal range pattern is either dampening, a mix of dampening/amplification, or amplification, SLR increases (up to 61 %), moderately increases (up to 26 %), and slightly decreases/increases (up to 5 %) the tidal range of estuaries, respectively. Considering the relationship between an estuary's present-day tidal range pattern and its response to SLR, the presented approach may be useful in providing an initial assessment of SLR effects in estuaries worldwide. This approach may also help to identify sites most impacted by future SLR, and to direct decision-making towards evidence-based management approaches.

Upland river planform morphodynamics and associated riverbank erosion: Insights from channel migration of the upper Yarlung Tsangpo river

River meandering and lateral migration, caused by riverbank erosion, is a major global threat to soil, sediment, lands, and habitats. However, compared to the densely populated lowland floodplains, the upland channel morphodynamics of free-flowing rivers in a complex high-elevation alluvial setting have received less attention. In this study, we quantitatively investigated channel morphodynamics and associated frozen bank migration in the upper Yarlung Tsangpo River in the Himalayan headwater basin from the 1980s to the 2010s. By combining remote sensing analysis with field investigations, we found mean migration rates of 244 gravel-bed river bends ranging from 1.63 m/yr in the 1980s to 2.76 m/yr in the 2010s, with a maximum rate of 18.61 m/yr. The highest migration rates were associated with bends that had a width-normalised curvature radius between 3.0 and 5.0 and a sinuosity between 1.2 and 1.5. A ∼69% increase in river-bend migration and 30% more frequent bend cutoffs coincided nicely with the rapid expansion of glacial lakes due to a ∼1 °C increase in mean annual air temperature over the past four decades. Positive correlations were observed between channel migration rate and temperature, mean glacial lake area, and runoff. These results highlight the importance of the unique channel morphodynamics and the intense lateral movements of upland rivers. The close link between these dynamics and climate change suggests that a warmer world may significantly influence bank erosion and associated ecosystem processes of upland alluvial systems, which are essential for comprehending frozen channel dynamics and developing strategies for habitat protection in uplands worldwide.

Macrophyte-Based Assessment of Upland Rivers: Bioindicators and Biomonitors

For the first time, a macrophyte-based assessment of ecological status was related to the accumulated heavy metals and trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) in aquatic plants. Three moss and two vascular plant species were applied as biomonitors: Fontinalis antipyretica Hedw., Leptodictyum riparium (Hedw.) Warnst., Platyhypnidium riparioides (Hedw.) Dixon, invasive Elodea canadensis Michx., and Myriophyllum spicatum L. Three streams were assessed as good at a high ecological status which correlated with low contamination based on calculated contamination factors (CFs) and metal pollution index (MPI). Two sites evaluated in moderate ecological status were revealed to be in heavy trace element contamination. The most significant was the accumulation of moss samples from the Chepelarska River under mining impact. Mercury exceeded the environmental quality standard (EQS) for biota in three of the studied upland river sites.

Colonization of Artificial Substrates by Invertebrate Macrofauna in a River Ecosystem-Implications for Forensic Entomology.

Forensic entomology includes the analysis of organisms colonizing various parts of the body in order to determine the circumstances of an incident, mainly the time, place, and cause of death. The presence of insects and other arthropods on carcasses can be a source of knowledge for the judicial system. However, this type of research (on submerged bodies) is less published. The aim of our study was to analyse the qualitative and quantitative structure of macroinvertebrates colonizing potential evidence in an upland river. The experimental research involved an eight-week exposure to articles of clothing made of different materials: natural materials (bottom sediments with plants from a river), synthetic (socks), and cotton (t-shirts). Control samples of water after 2, 4, 6, and 8 weeks were taken from experiment locations in the River Bystrzyca with a tube apparatus and hand net. The results indicated that the abundance of organisms on a given substrate depended on the period of development of invertebrate macrofauna and the time of exposure of the substrates. The abundance of aquatic macrofauna on the exposed items increased in direct proportion to the duration of the experiment, which may indicate the adaptability of these organisms to new habitat conditions. Among the taxonomic groups used in forensic entomology, Diptera, Coleoptera, and Odonata were the most abundant. The remaining taxa (including Heteroptera), though not widely used in judicial proceedings, can also provide valuable information about the circumstances of an incident.

Forecasting Monthly River Flows in Ukraine under Different Climatic Conditions

River-flow forecasts are important for the management and planning of water resources and their rational use. The present study, based on direct multistep-ahead forecasting with multiple time series specific to the XGBoost algorithm, estimates the long-term changes and forecast monthly flows of selected rivers in Ukraine. In a new, applied approach, a single multioutput model was proposed that forecasts over both short- and long-term horizons using grouped or hierarchical data series. Three forecast stages were considered: using train and test subsets, using a model with train-test data, and training with all data. The historical period included the measurements of the monthly flows, precipitation, and air temperature in the period 1961–2020. The forecast horizons of 12, 60, and 120 months into the future were selected for this dataset, i.e., December 2021, December 2025, and December 2030. The research was conducted for diverse hydrological systems: the Prut, a mountain river; the Styr, an upland river; and the Sula, a lowland river in relation to the variability and forecasts of precipitation and air temperature. The results of the analyses showed a varying degree of sensitivity among rivers to changes in precipitation and air temperature and different projections for future time horizons of 12, 60, and 120 months. For all studied rivers, variable dynamics of flow was observed in the years 1961–2020, yet with a clearly marked decrease in monthly flows during in the final, 2010–2020 decade. The last decade of low flows on the Prut and Styr rivers was preceded by their noticeable increase in the earlier decade (2000–2010). In the case of the Sula River, a continuous decrease in monthly flows has been observed since the end of the 1990s, with a global minimum in the decade 2010–2020. Two patterns were obtained in the forecasts: a decrease in flow for the rivers Prut (6%) and the Styr (12–14%), accompanied by a decrease in precipitation and an increase in air temperature until 2030, and for the Sula River, an increase in flow (16–23%), with a slight increase in precipitation and an increase in air temperature. The predicted changes in the flows of the Prut, the Styr, and the Sula rivers correspond to forecasts in other regions of Ukraine and Europe. The performance of the models over a variety of available datasets over time was assessed and hyperparameters, which minimize the forecast error over the relevant forecast horizons, were selected. The obtained RMSE parameter values indicate high variability in hydrological and meteorological data in the catchment areas and not very good fit of retrospective data regardless of the selected horizon length. The advantages of this model, which was used in the work for forecasting monthly river flows in Ukraine, include modelling multiple time series simultaneously with a single model, the simplicity of the modelling, potentially more-robust results because of pooling data across time series, and solving the “cold start” problem when few data points were available for a given time series. The model, because of its universality, can be used in forecasting hydrological and meteorological parameters in other catchments, irrespective of their geographic location.

Spatio-temporal differences dominate suspended sediment dynamics in medium-sized catchments in central Germany

Suspended sediment transport, dominating material export from lowland river systems, is highly variable in space and time. Since suspended sediment transport can have adverse effects on human infrastructure, targeted management is imperative. To achieve this, a thorough understanding of suspended sediment dynamics is needed, but requires long-term monitoring data. Despite studies investigating suspended sediment dynamics on decadal time scales, an assessment of the spatio-temporal variability across adjacent river catchments is still lacking.To fill this gap, we analyse suspended sediment transport at twelve stations along German upland rivers, monitored on a daily basis for 28 to 54 years. All monitoring stations belong to the Rhine (Lahn, Lippe, Main, and Neckar) and Weser river systems (Fulda, Leine, Werra, and Weser) and have contributing areas between 2500 and 22,000 km2. Although located in comparable topo-climatic settings, average sediment yield for the monitoring period varied more than fourfold. Covering the range of 5.9 to 28.7 t km−2 yr−1, we found the highest and lowest suspended sediment yields for the Neckar and Lippe catchments, respectively. Using two different streamflow separation approaches, we estimated the contribution of stormflow discharge to total sediment transport to fall between 73 and 85 % in the Neckar and Lahn rivers while remaining ~15 % lower for the remaining catchments. Investigating the relevance of extreme events, we found the share of total suspended sediment load transported during the ten largest events to vary between ~28 % for the Neckar and ~8 % for the Lippe and Werra catchments. These events were predominantly characterized by clockwise hysteresis loops that hint to in-channel reworking as a significant material source, with the exception of the Neckar stations where anti-clockwise hysteresis patterns prevailed. Here, the hysteresis analysis indicates sediment delivery from more distant sources in the headwater regions, likely related to elevated rainfall intensities and the susceptibility of the escarpment of the Swabian Alb towards landsliding. We conclude that the combined effect of varying rainfall amounts and intensities, the fraction of steeper slopes as well as lithological differences explain the across-catchment variability on multiple time scales that is further modulated by river management practices.

Factors controlling floodplain sediment storage in two tropical upland river catchments in the Lake Tana basin, Ethiopia

Floodplain sediment storage is an important component of a catchment’s sediment budget. Here, we present the first quantification of floodplain sediment storage for tropical river catchments draining to Lake Tana, NW Ethiopia. The catchments are characterized by relatively gently sloping to flat lowlands towards the lake (1788 m a.s.l.) and steeper river reaches in the uplands towards Mount Guna (4120 m a.s.l.). Sediment storage for 65 homogeneous floodplain segments was estimated by combining information on floodplain spatial extent obtained through the field- and remote sensing-based approaches, with information on sediment thickness obtained through sediment coring and the analysis of river cut-banks. Extrapolation to the entire catchment was done making use of floodplain typology and following the classification scheme of Nanson and Croke (1992) and other floodplain properties and catchment-wide variables. The results showed average sediment storage of 284 Mg m−1 river length or 21,760 Mg ha−1 floodplain area for the Gumara and approx. 227 Mg m−1 river length or 16,909 Mg ha−1 floodplain area for the Rib River catchments. Total floodplain sediment storage at the catchments scale, above the upper gauging stations, amounts to 92.9 Mt and 35.5 Mt for the Gumara and Rib River catchments, respectively. At the scale of homogeneous floodplain segments, sediment storage is related to floodplain width, floodplain slope, upstream catchment area, the average slope of the upstream catchment area, sinuosity, and floodplain type. Overall, floodplain geomorphology largely controls sediment storage. Approx. 70 % of the sediment is stored in low-energy cohesive floodplains which only take up 11 % of the total river length in both catchments. For most of the total river and valley extent, where rivers are incised and have more energy, storage is limited. Comparing our findings with similar studies in temperate catchments of Europe and N-America showed that sediment storage in the Gumara and Rib Rivers is lower by approx. 1 order of magnitude, for similar-sized catchments.

EDEL DANCE: A HEALING RITUAL OF TAGAKAULO TRIBE OF BARANGAY DATU DANWATA IN MALITA, DAVAO OCCIDENTAL

For millennia, faith healing has been practiced in many nations to prevent, diagnose, and treat health issues (Peprah, P., et al., 2019). Faith healing is the concept that by having faith, one may be healed. Prayer or supernatural intervention are generally used to accomplish this. The goal of this research is to learn more about Edel Dance: A Healing Ritual of the TagaKaulo Tribe in Barangay Datu Danwata, Malita, Davao Occidental, Philippines. Storytelling, focus group discussions, observations, and in-depth interviews are all used by the researcher. Families that took part in the Edel Dance enjoyed spiritual, bodily, and emotional healing, especially when a sibling died. Their God, who created humanity and the cosmos, was tied to this concept. As a result, traditional methods of thinking and doing things have been preserved and continue to be practiced today. The Tagakaulo Tribe has traditionally resided in the provinces of Davao Del Sur and Sarangani, particularly in the towns of Malalag, Lais, and Talaguton Rivers, Santa Maria, Davao Occidental, and Malita and Malungon, Sarangani. The Tagakaolo tribe traveled south of Mt. Apo from the Davao Gulfs western beaches a long time ago. There are around 71,356 native speakers in the country (2000, SIL International). Tagakaulo is connected to the Mandaya, Kalagan, and Kamayo dialects and belongs to the Austronesian and Malayo-Polynesian language families. Tagakaulo means headwater dwellers (olo sa tubig) or headwater dwellers (olo sa tubig) or headwater dwellers (olo sa tubig) or headwater dwellers (olo sa tubig Lowland, coastal, riverine, valley, mountain, highland, and plain habitats were all present. Their main sources of income were agriculture, fishing, and paid labor, and they lived completely sedentary lives. Primogeniture runs across each upland river valley or highland plain (right of succession belonging to the firstborn child). The datu, who is in charge of civic and labor obligations, is a significant person in their culture; a powerful datu may be captured or purchased. Each datu is the self-governing chief of a region. The Tagakaulo tribe’s lifestyle is influenced by religious beliefs, ceremonies, and customs. They are touched by supernatural phenomena because they think ghosts are also part of the community. Their religious views represent their relationship with the divine realm, which has an impact on how they should act, behave, and interact with the unseen world. As a result, traditional belief systems and rituals have survived and continue to be practiced today. All aspects of our life are influenced by cultural belief systems and customs. As a result, in order to preserve these notions and traditions, research that is in tune with other cultures beliefs and practices should be promoted. Furthermore, studies like these will aid in the spread of understanding as well as acceptance and respect for diverse faiths views, practices, and faith. KEYWORDS: Edel Dance, healing,Tagakaulo Tribe, Faith healing

A riverine biodiversity hotspot in northern Myanmar supports three new and narrowly endemic freshwater mussel species

Abstract The Western Indochina Subregion (Myanmar) represents a freshwater biodiversity hotspot of worldwide significance and houses a plethora of endemic freshwater species, among which are amphibians, fish, and various aquatic invertebrates. The freshwater mussel (Bivalvia: Unionidae) fauna of western Indochina is characterized by high taxonomic richness, with almost all species and several genera being endemic to the subregion. Furthermore, there are a number of species endemic to a single basin or even to a single tributary of a larger river system (the so‐called intra‐basin endemic taxa). Here, the discovery of three new, narrowly endemic freshwater mussel species from northern Myanmar is presented: Radiatula kachinensis sp. nov., Trapezidens mogaungensis sp. nov. (upper Ayeyarwady basin), and Lamellidens chindwinensis sp. nov. (upper Chindwin basin). All the new species are upland river specialists, which are under high human pressure as a result of habitat degradation, deforestation, oil palm expansion, river damming, and biological invasions. A nearly complete lack of data on the life cycles and fish hosts should be considered the most striking gap in recent knowledge of tropical Asian freshwater mussels. Here, available data on 27 species belonging to the genera Radiatula, Trapezidens, and Lamellidens are revised. It is shown that certain fish hosts are known for two species only. Further spread of the alien Chinese pond mussels (Sinanodonta woodiana species complex) in Indochina may be considered one of the significant threats to native freshwater mussel populations. Here, it is shown that the temperate invasive lineage of S. woodiana is established in at least three non‐native populations in the Ayeyarwady and Salween basins. Moreover, the first arrival of the tropical invasive lineage of S. woodiana to Myanmar is announced, although it has been predicted previously. This lineage was found at two sites on the Shan Plateau (Ayeyarwady basin) close to the Chinese border.

The Impact of Pollution on Diversity and Density of Benthic Macroinvertebrates in Mountain and Upland Rivers

This article summarizes the studies concerning the impact of pollutants on benthic macroinvertebrate communities in the mountain and upland rivers of southern Poland. The Carpathian Raba River, which in the 1960s retained its natural character and had good water quality, was considered as a reference in terms of benthic macroinvertebrate communities. The other two analyzed rivers were polluted to different degrees. The Carpathian Dunajec River was contaminated mainly by sewage from small towns and treatment plant, while the upland Vistula River mainly by sewage from the Upper Silesian Industrial Region and saline waters from coal mines. In studied ecosystems in response to pollutions, a rapid increase in density of fauna caused mainly by the massive development of Oligochaeta was found. In the mountain river, the impact of contamination on macroinvertebrate diversity was negligible. There, taxa considered as indicators of clean water (Ephemeroptera, Plecoptera, and Trichoptera) were abundant and their diversity was similar to that of an uncontaminated river. In the heavily polluted upland Vistula River, the sites with a muddy bottom were dominated by Oligochaeta (99.4–99.9%), while at sites with stony bottoms, apart from Oligochaeta, there were also Chironomidae, Gastropoda, and Hirudinea. In comparison to the 1950s, all Ephemeroptera, Plecoptera, Odonata, Trichoptera, and Megaloptera were extinct.

Optimization schemes for deep foundation pit dewatering under complicated hydrogeological conditions using MODFLOW-USG

The design and optimization of the dewatering scheme for deep foundation pits in a highly permeable heterogeneous layer are critical to protect water resources, control subsidence and mitigate environmental impacts. Numerical simulation is an important and sometimes the only tool in the design of dewatering schemes, especially when the dewatering projects are planned under complex hydrogeological conditions with limited data. The open excavation method was chosen for a project to drain a deep foundation pit (35–44 m) in an upland river valley landscape. Quaternary alluvial deposits (129.0 m thick) are generally distributed in the riverbed and the overburden consists mainly of alluvial-diluvial sandy gravel cobbles, clayey soils, sandy clay, and silty fine sand, making the study area very heterogeneous. There may be water inrush from foundation pit, uneven subsidence and deformation due to the uneven structure of the sand and slope stability. MODFLOW-USG (Unstructured Grid) and Subsidence and Aquifer-System Compaction (SUB) Package were used to create a coupled 3-D groundwater flow-subsidence numerical model for foundation pit dewatering. MODFLOW-USG provides greater flexibility in the design of the grid to achieve a high degree of accuracy in numerical simulation, while effectively reduces computational costs. A combination of waterproof curtain and a partial penetrating well was proposed for lowering the groundwater table. The optimized dewatering scheme with a curtain depth of 60 m and a hydraulic conductivity of 0.00518 m/d, and four rows of dewatering wells with an equal row spacing of 40 m, well depth of 50 m, and well spacing of 12.5 m in each row can meet the dewatering requirements with minimum groundwater discharge in the scenarios. The numerical simulation of this study provides a powerful and useful tool for dewatering and subsidence control of deep foundation pit under complex hydrogeological conditions.

Change in beta diversity of riverine fish during and after supra-seasonal drought

ContextA core theme in ecohydrology is understanding how hydrology affects spatial variation in the composition of species assemblages (i.e., beta diversity). However, most empirical evidence is from research in upland rivers spanning small spatial extents. Relatively little is known of the consequences of hydrological variation for beta diversity across multiple spatial scales in lowland rivers.ObjectivesWe sought to examine how spatial variation in hydrology and fish beta diversity within and among rivers changed over time in response to intensification and cessation of hydrological drought.MethodsWe used monitoring data of fish assemblages, coupled with hydrological and biophysical data, to test how spatial variation in hydrology and multiple components of fish beta diversity in lowland rivers of the Murray—Darling Basin (Australia) varied across spatial scales during contrasting hydrological phases.ResultsSpatial variation in hydrology among rivers declined with increasing duration of drought before increasing during a return to above-average flows. Spatial variation in hydrology within rivers did not show consistent changes between hydrological phases. Beta diversity among and within rivers showed variable, river-specific changes among hydrological phases for both incidence- and abundance-based components of assemblage composition.ConclusionsInconsistent hydrology—beta diversity patterns found here suggest that mechanisms and outcomes of drought and flooding impacts to beta diversity are context-dependent and not broadly generalisable. Our findings indicate that hydrological fluctuations occurring in the Murray—Darling Basin in the period analysed here did not cause significant or consistent homogenisation or differentiation of freshwater fish assemblages.