River Bank Research Articles

CHEMICAL AND MICROBIOLOGICAL DIVERSITY DETECTED IN WATER BODIES IN THE MUNICIPALITY OF BARCARENA/PA, AMAZONIA, BRAZIL

Population growth linked to greater exploitation of nature compromises the quality of water, which is considered a limited natural resource and is vitally important for the survival of living organisms and directly influences the economy, leisure, culture and the social environment. This study evaluated the physicochemical, toxicological and microbiological parameters of rivers and streams in the municipality of Barcarena, State of PA, Amazonia, Brazil. We collected 58 samples in the period from 2021 to 2022. The average values ​​verified were above the limits allowed by Brazilian legislation (CONAMA 357/2005) for true color (µ = 218.09 ± 223.843), BOD (µ = 31.30 ± 64.992) and Escherichia coli (µ = 1243.76 ± 2838.743) in stream samples when compared to those from the river, demonstrating that there are statistical differences in these parameters between these two environments. We also analyzed traces of 10 toxic metals (Al, B, Ba, Be, Cd, Co, Cr, Cu, Li, Pb). The average levels of these pollutants ranged from 0 (<LD) to 1,504 mg/L. The highest concentration was found for Aluminum, which ranged from 0.003 to 1.504 mg/L with an average of 0.275 ± 0.289 mg/L. The greatest concentration similarity (75.16%) of these soluble metals was observed between the Pará river and the Dendê stream. Therefore, the studied area presents contamination of aquatic ecosystems due to mining activity, which has caused serious impacts on the remaining communities on the banks of the municipality's rivers that cross the Municipality of Barcarena-Pa.

Hair coat of the water deer <I>Hydropotes inermis</I> (Cervidae, Artiodactyla) – a new species in the fauna of Russia

For the first time, the hair cover and hair microstructure of an adult male Hydropotes inermis from the Primorsky region of Russia were studied using light and scanning electron microscopy. The absence of abundant underfur, sparse wool and its weak layering are characteristic of this inhabitant of the temperate monsoon and tropical zones, which does not need an effective thermal protection.The alveolar and lattice medulla of the hair is similar to that of other deer, is well developed, and increases the heat-protective properties of the hair, since seasonal and daily fluctuations in temperature and humidity can be significant. The cuticle pattern is similar to that of deer tribes Alceini and Capreolini. The hair serves as reliable protection for the water deer from mechanical damage when moving through thickets of bushes and grasses along the banks of rivers and swamps in the biotopes that this deer inhabits, which is facilitated by the significant thickness and length of the hairs on the back, sides and thighs. The knotty nature of the hairs protects the deer’s skin from the sharp growths of aquatic and marsh plants.

Geo-spatial analyses of meandering rivers, assessing past and future impacts on bank landforms and LULC changes

ABSTRACT Morphological investigation of rivers is difficult but is one of the vital topics for the management of highly meandering river systems. The study employs GIS to analyse 32 years of Barak River data, addressing challenges in quantifying the morphology of meandering rivers. Earth observatory data from 1990 to 2022 track channel bank shifts and Land Use/Land Cover (LULC) alterations. Although the digital shoreline analysis system (DSAS) model identified long-term bank line migration analysis of shorelines, it's use is very new for rivers, especially in terms of the meandering of rivers. Conversely, research on long-term meandering river morphology in the Barak River channel has not been conducted despite evident land-use changes. Using DSAS for bank positions and CA–Markov models for LULC , future projections until 2043 reveal ongoing Barak River bank shifts and significant LULC pattern alterations. The findings of the research were validated through RMSE, Student's t-test, chi-square, and the kappa coefficient. Forecasts indicate that rapid urbanization impacts river morphology. The methodology is crucial for managing highly meandering rivers, particularly in contexts involving vulnerable river systems.

The Need to Maintain the Quality of Naturally Pure Water of Sarayu River

Rivers are a link between human life and nature. All the ancient developed cities are situated on the banks of some river or the other ancient civilizations of India have developed on the banks of rivers. The river is helpful in both, flood and drought conditions, works to balance nature by absorbing the flood water inside itself and giving water to animals and humans during drought. In the present scenario, due to the increasing population of cities and the pollution arising from it, the water of rivers is getting polluted rapidly. Many rivers of the country are slowly disappearing and some rivers have water only during monsoon. Our country is slowly moving towards water crisis. To get out of this crisis, we all need a corrective change in behaviour along with scientific remedial system. The per capita availability of water has decreased significantly in the last 75 years. According to one figure, in 1951 the per capita was 5177 cubic meters but in the year 2011 only 1545 cubic meters of water is available per person. According to a study by the National Institute of Hydrology, India will have only 814 cubic meters of usable water per capita in 2025. When we studied the water of Sarayu river, it was found that all the parameters and heavy metals present in the water raised after monsoon are within the processed limit. When the properties of the water of Sarayu river were studied, surprising results came out. All the elements present in the water like calcium, magnesium, chloride, fluoride, alkalinity, nitrate ion, sulphate ion, arsenic and manganese etc. were within the required limits. Desirable limits of calcium, magnesium, chloride, alkalinity, nitrate ion, sulphate ion are 75 mg/l, 30 mg/l, 25 mg/l, 200 mg/l, 200 mg/l, respectively. The maximum values in pre-monsoon were found to be 38.47 mg/l, 26.24 mg/l, 15.9 mg/l, 192 mg/l, 0.20 mg/l and 20.10 mg/l respectively and in post-monsoon its maximum value was found to be 28.86 mg/l, 12.49 mg/l, 17.99 mg/l, 128 mg/l, 1.5 mg/l and 41.30 mg/l, respectively. The desirable limit of arsenic is 0.01, found to be 0.01 at some places in pre-monsoon but found to be nil in post-monsoon.

IDENTIFIKASI DAN KARAKTERISTIK MORFOLOGI POLEN PAKAN KUPU-KUPU (IMAGO) DI JALUR WISATA GOA SAMPE MARTA KABUPATEN KUTAI KARTANEGARA KALIMANTAN TIMUR

ampe Marta Cave Tourism is located in Kutai National Park, Kutai Kartanegara Regency, East Kalimantan, and is one of the natural tourism areas with high biodiversity. The tourist route in this area offers natural beauty and a habitat that supports the lives of various butterfly species. This study aims to identify plants that are food sources (nectar) and non-nectar, types of butterflies, and the characteristics of pollen from each food plant. This study uses the transect method, namely taking samples of flowers and butterflies along the route, and the acetolysis method to see the morphological characteristics of pollen. The results of the study showed that there were 19 species from 11 families of nectar-eating plants identified as being utilized by butterflies (imago) as a source of nectar, where Ageratum conyzoides (Asteraceae), Asystasia gangetica (Family Acanthaceae), Leea indica (Family Vitaceae) were the dominant species that were often visited. In contrast, non-nectar feed such as minerals, rotten fruit, and animal feces, where out of 14 butterfly species identified, 11 dominant species sucked minerals on the banks of rivers or mud puddles, two species visited rotten fruit, and one species was seen in animal feces. Nectar feed has the characteristics of large and round-elongated pollen, which is more efficient for sticking to the insect's body. In contrast, the round-elongated oblate shape in Oxalis barrelieri shows strategic differences in the transfer of varying pollen norms, such as echinate and scabrate. The results of this study can be a reference for butterfly researchers to provide an overview of the diversity of nectar-producing plant feed along with its morphological characteristics and non-nectar feed utilized by butterflies on the Sampe Marta Cave tourist route

Mapping Soil Surface Moisture of an Agrophytocenosis via a Neural Network Based on Synchronized Radar and Multispectral Optoelectronic Data of SENTINEL-1,2—Case Study on Test Sites in the Lower Volga Region

In this article, the authors developed a novel method for the moisture mapping of the soil surface of agrophytocenosis using a neural network based on synchronized radar and multispectral optoelectronic data from Sentinel-1,2. The significance of this research lies in its potential to enhance precision farming practices, which are increasingly vital in addressing global agricultural challenges such as water scarcity and the need for sustainable resource management. To verify the developed method, data from two experimental plots were utilized. These plots were located on irrigated soybean crops, with the first plot situated on the right bank (plot No. 1) and the second on the left bank (plot No. 2) of the lower Volga River. Two experimental soil moisture geodatasets were created through measurements and geo-referencing points using the gravimetric method (for plot No. 1) and the proximal sensing method (for plot No. 2) employing the Soil Moisture Sensor ML3-KIT (THETAKIT, Delta). The soil moisture retrieval algorithm was based on the use of a neural network to predict the reflection coefficient of an electro-magnetic wave from the soil surface, followed by inversion into soil moisture using a dielectric model that takes into account the soil texture. The input parameter of the neural network was the ratio of the microwave radar vegetation index (calculated based on Sentinel-1 data) to the index (calculated based on the data of multispectral optoelectronic channels 8 and 11 of Sentinel-2). The retrieved soil moisture values were compared with in situ measurements, showing a determination coefficient of 0.44–0.65 and a standard deviation of 2.4–4.2% for plot No. 1 and similar metrics for plot No. 2. The conducted research laid the groundwork for developing a new technology for remote sensing of soil moisture content in agrophytocenosis, serving as a crucial component of precision farming systems and agroecology. The integration of this technology promotes sustainable agricultural practices by minimizing water consumption while maximizing crop productivity. This aligns with broader environmental goals of conserving natural resources and reducing agricultural runoff. On a larger scale, data derived from such studies can inform policy decisions related to water resource management, guiding regulations that promote efficient water use in agriculture.

Long-term effects of Abay River flow regulation at Lake Tana on the geomorphic and ecological responses of the downstream river channels, Upper Blue Nile basin, Ethiopia

Alluvial rivers adjust their geometry in response to environmental and anthropogenic disturbances. Flow regulation results in a new geomorphic condition that affects the aquatic ecosystem and its nature. This paper examines the long-term effects of flow regulation on the geomorphic and ecological responses of the downstream river channels of the Abay River, which is the only natural outflow of Lake Tana, Ethiopia. Since 1996, the river’s discharge regime has been affected by constructing a head-rise weir (Chara Chara) at its natural outlet for hydropower production and dam construction on the Lake Tana tributary rivers. Hydrologic data collected at the outlet of the river, SPOT, and Google Earth images were used for the study. River banks and bed topography were extracted via ArcGIS for selected study periods. The study revealed that existing water resource development on the tributary rivers of Lake Tana modified (decreased) the outflow discharge on the Abay River, and resulted a changed morphological and moderate level ecological impact on the river system. Future ongoing and planned water resource developments will exacerbate the pressure on the lake. Without careful management, these changes are likely to have severe morphological, ecological and social consequences.

Evaluation of Fuel Consumption and Exhaust Emissions in a Single Cylinder Four-Stroke Diesel Engine Using Biodiesel Derived from Chicken Waste with Additives

Biodiesel is a renewable, locally generated fuel made from vegetable oils, trans fats, or recycled restaurant grease for use in diesel automobiles and other diesel-powered equipment. The physical qualities of biodiesel are comparable to those of petroleum diesel. Biodiesel is used in compression-ignition engines in the same way as petroleum diesel. Biofuel can be made from biomass, but according to the Indian National Policy on Biofuels, biofuel extraction from edible oils is not permitted because it would result in a massive increase in consumer goods prices and perhaps lead to product scarcity. Hence, there is a need to search for alternative biofuel so that it does not affect our nation's national policy. Recently there has been a drastic increase in the consumption of chicken grown in farms. There is a huge problem in disposing of their waste. One major difficulty in waste treatment is poultry manure, often known as slaughter waste. This waste is sometimes dumped on wastelands, roadsides, and the banks of rivers, lakes, and ponds. This creates more sanitary problems for society. According to polls, poultry feces begin to decompose in around three hours. The odor of butcher's waste causes a lot of pollution in the air, as well as an increase in the density of bacteria in the atmosphere. Measures have been taken by the government for the safe disposal of these wastes. One of the major ways of disposal is to recycle this chicken slaughter waste in a useful manner so that it can serve society in a positive way. This could be done by converting this waste into fuel through various processes such as rendering, hydrolysis, extraction, acid esterification, alkaline transesterification, and finally by the extraction process. This produced fuel could be blended with existing diesel in varying concentrations and used in diesel engine-powered vehicles. In this work, the fuel is extracted from the chicken waste and blended with pure diesel and an Al2O3 additive in various proportions. These combinations are then tested on a single-cylinder diesel engine for fuel consumption and emission analysis. The results exhibited an overall better performance when compared to pure diesel.

Enhancing streamflow prediction in the Wujiang River basin: a two-stage decomposition approach with deep learning integration

ABSTRACT Global climate change and human activities have profoundly impacted the geological and hydrological processes in watersheds, increasing the challenges in streamflow prediction. In this study, we propose a streamflow prediction model based on deep learning and dual-mode decomposition specifically tailored for the Wujiang River basin, a significant tributary on the southern bank of the upper Yangtze River. This model effectively addresses the prediction error issue caused by high-frequency components through dual-mode decomposition of time-series data. The results demonstrate that employing the coupled complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN)–variational mode decomposition (VMD)–temporal convolutional network (TCN)–long short-term memory network (LSTM) model reduces prediction errors by at least 35% compared to single decomposition models. Furthermore, compared to individual TCN or LSTM models, the TCN–LSTM coupled model exhibits greater stability and higher prediction accuracy during training, with reductions in mean absolute error and root mean square error by 43.13 and 24.57%, respectively. This model holds promising prospects for application and can provide crucial insights for water resource management.

Assessment of the Local Strategies Used in Abating Flash Floods for Improvement of Community Livelihoods in Nyamwamba and Bulembia Divisions, Kasese District, Uganda

Floods are intricate events that cause a range of human exposures, including loss of lives, property, and damage to infrastructure of the communities. Flash floods though often blamed on inappropriate development planning and climate variability, floods can be predicted to a reasonable extent, whose scale and nature are often less certain. The study aims at assessing the local strategies used in abating flash floods for improvement of community livelihoods. Specifically, the study explored the challenges the local communities faced during the implementation of the strategies, and also determined the relationship that emanated as a result of implementing the local strategies and community livelihoods. The study adopted a descriptive cross-sectional survey design, collecting both quantitative and qualitative data from 218 respondents and 08 Key Informants that held key responsibilities at the Municipal Council and the community. Information from the respondents and Key Informants were collected using questionnaires which was in form of interviews and face to face interviews respectively. The study shows that some local strategies have been implemented towards controlling flash floods such as, restoration of river banks (69.3%) planting bamboo trees along river banks (66%), use of gabions (65.6%), putting check dams (65.6%) and construction of manmade channels (95.9%) along the hillsides. Putting flood barriers (73%) that floods affect the community livelihoods in various aspects of daily life and the local economy in terms damage of crops (74.8%) risk of diseases (83 %) loss of livestock (60 %), displacement (93%); The challenges faced in implementation of the of local strategies in the study area include financial constraints (81.2%), technical and logistical issues (63%), poor infrastructural design (83.9%), and environmental challenges (66%). A Chi square test showed that the implemented local strategies were significantly related to the community livelihood at P=0.001. Implemented local flood strategies resulted to a positive relationship to the agricultural productivity and protected community property at P<0.05. Overall, effective flood management strategies are able to reduce risks and contribute to a better community health with fewer disruptions to community’s daily life at P<0.05. Local communities should adopt and implement the use of the mentioned local strategies like re-channeling of water pathways along the hill sides and use of gabions for flash floods mitigation since they cost effective. There should be a country-wide implementation of community-initiated mitigation measures for abating flash floods and related climate change disruptions aimed at building and promoting community resilience and livelihoods of people living in flood prone areas.

A New Species of Crepidium (Orchidaceae: Epidendroideae: Malaxideae): From Assam, North East India

ABSTRACTA new species of the tribe Malaxideae (Orchidaceae), Crepidium assamicum, is described and illustrated here as new species from Assam, North East India. The new taxon is superficially similar to Crepidium purpureum but differs in its habitat, plant size, long floral bract, very densely flowered inflorescences, leaf number, larger petiole size, both winged throughout and flower color. This species is confined to grow in open grassland near river bank of Dibru‐Soikhowa, Dibrugarh district of Assam, in a huge population comprising 500–600 individuals. The threat status of this new species is provisionally assessed here as “Threatened” following the IUCN Red List Categories and Criteria version 16 (2024).

The effect of urbanization on planktonic and biofilm bacterial communities in different water bodies of the Danube River in Hungary

Freshwaters play an essential role in providing ecosystem services worldwide, however, the water quality of different water bodies is strongly influenced by human activities such as urbanization, industry and agriculture. In this study, water and biofilm samples were collected from the main channel of the Danube River upstream and downstream of a metropolitan, from a regulated side arm within an urbanized area, and from two differently separated oxbow lakes located in nature conservation areas. The taxonomic diversity of bacterial communities was revealed by 16S rRNA gene-based amplicon sequencing using Illumina MiSeq platform. The results showed that all samples were dominated by phyla Pseudomonadota, Actinobacteriota and Bacteroidota. The bacterial community structures, however, clearly differentiated according to planktonic and epilithic or epiphytic habitats, as well as by riverine body types (main channel, side arm, oxbow lakes). The taxonomic diversity of biofilm communities was higher than that of planktonic ones in all studied habitats. Human impacts were mainly reflected in the slowly changing biofilm composition compared to the planktonic ones. Genera with pollution tolerance and/or degradation potential, such as Acinetobacter, Pseudomonas and Shewanella were mainly detected in biofilm communities of the highly urbanized section of the river side arm.

Epigaeic spiders (Araneae) from three habitats at Stryn, Nordfjord, Western Norway

One year of pitfall sampling in (A) a narrow strip of vegetation (junipers, Rosa sp., small pines) close to a river bank, (B) a cultivated medium humid meadow and (C) a humid deciduous forest (Alnus) with some grass on the ground collected a total of 25, 48 and 32 species, respectively (in total 67 species). Shannon indices of general diversity (ln e) were 1.8, 2.1 and 3.1, respectively. The three sites shared only 9 species, 57% of all species were found in only one locality. Similarity indices were low, especially between loc. A and C. Linyphiidae and Lycosidae were dominant. The latter were scarce in loc. B and C but common at loc. A (Pardosa palustris and P. amentata together comprising 43.5% of total) and net building species more scarce. The local distribution, co-existence, ecological and habitat preferences, seasonal activity and body size of some common species are briefly discussed. For some species, aspects of geographical distribution are discussed.

Exploring the distribution pattern of native and alien forests and their woody species diversity in a small Mediterranean city

Recent studies have explored the ecological relationship between native urban forests and self-sown non-native forests in large cities and metropolises but further research efforts dedicated to analyzing this relationship in small cities are still needed. To improve our understanding of the ecology of urban native and alien forests in Mediterranean small cities, we analyzed the woody species richness, the community-weight mean of moisture and nitrogen ecological indicators, and soil disturbance indicators in the main urban wood types of the city of Campobasso (Italy), as well as their spatial distribution pattern across a gradient of cover and aggregation of green areas. The study showed that both native oak forests and Robinia pseudoacacia forests contributed to the maintenance of woody species richness. If we exclude the riparian environment, R. pseudoacacia forests occupied small marginal patches, tolerating soil disturbance and a high disturbance frequency, thus occupying habitats where the native oak forests could not grow. Conversely, R. pseudoacacia forests shared the ecological niche with the native riparian forests, which calls for action to prevent the spread of this alien species along river banks. Our results highlighted that urban remnant forests should be considered important assets for the planning and upkeep of urban green areas.

Hidden species diversity in the Enteromius Cope, 1867 (Teleostei: Cyprinidae) from the Aruwimi basin (Middle Congo) in the Okapi Wildlife Reserve (Democratic Republic of the Congo).

Two new African minnow species, Enteromius cerinus sp. nov. and Enteromius ruforum sp. nov., are described for science from the Angadiko River, a left-bank sub-affluent of first order of the Nepoko River, draining the north-eastern part of the Okapi Wildlife Reserve (OWR). Both new species belong to the group of Enteromius for which the last unbranched dorsal-fin ray is flexible and underrated. Within this morphological group, both are most similar to Enteromius kamolondoensis, especially in life colour pattern characteristics. However, Enteromius cerinus sp. nov. differs from E. kamolondoensis by its low number of circumpeduncular scales, 10-11 (vs. 12), low maximum body depth, 22.8%-25.7% standard length (Ls) (vs. 26.1%-30.0%), and long anterior and posterior barbel lengths, 32.6%-35.3% head length (LH) (vs. 23.6%-27.2%) and 41.6%-43.9% LH (vs. 30.3%-34.9%), respectively. Further, E. ruforum sp. nov. is also easily distinguished from E. kamolondoensis by its high maximum body depth, 30.6%-33.3% Ls (vs. 26.1%-30.0%), and small, isometric, eye diameter, 26.2%-28.0% LH (vs. 29.1%-31.9%). A barcoding study (mtDNA, cytochrome oxidase subunit I [COI]) revealed that specimens of both new species form lineages well differentiated from those of other available species. As such, (i) E. cerinus sp. nov. diverges from E. kamolondoensis by a K2P genetic distance (GD) of 10.3% and (ii) E. ruforum sp. nov. by a K2P GD of 11.2%. To the present day, the fish fauna of the left-bank sub-affluents of the Nepoko River, in general, remains poorly known or undocumented. Unfortunately, at the same time, multiple anthropogenic impacts are affecting this fauna, such as (i) the destruction of habitats along the river banks for agriculture and fishing and (ii) the use of illegal fishing practices, such as fishing with plant-based ichthyotoxins during ecopage, which is combined with dam building. As a result of the demographic growth, this ecopage results in overfishing and thus is threatening both new species in particular, but all other co-occurring fish species as well. Both new species, E. cerinus sp. nov. and E. ruforum sp. nov., should thus be considered Vulnerable (VU) according to IUCN criterion D2. It is therefore hoped that their discovery highlights the urgent need for a better protection and further in situ exploration of the reserve's freshwater (fish) biodiversity, in general, and that of those small sub-affluents, in particular.

Water Quality Modeling of Wastewater Discharges for Prediction of Sediment Transport and Deposition in Surface Water

Sediment deposition in surface water bodies can have a range of significant impacts, affecting everything from the aquatic ecosystem to water quality and infrastructure. It can affect the availability of food sources for aquatic organisms; and change the physical structure of habitats, such as riverbeds and lake bottoms. It can equally smother aquatic plants and animals, leading to a decline in biodiversity. A model of the governing equations of particle motion and fluid flow was developed with COMSOL Multiphysics 5.3a. With a coefficient of determination of 0.99, the model result demonstrated good agreement after result validation using experimental data. According to study findings, sediments in the study area, Ele River move more slowly than sediments in the midstream which causes a high deposition of sediments at the river banks. This sediment deposition affects the irrigation system for crop production considering the ability of the sediments to block sprinkler nozzles which limits it from supplying sufficient water for the production of crops.

Characterization of Sedimentation Conditions Based on Composition of Organic Matter Dispersed in Rock of an Exploration Well on the Right Bank of the Ob River in Tomsk Oblast

Characterization of Sedimentation Conditions Based on Composition of Organic Matter Dispersed in Rock of an Exploration Well on the Right Bank of the Ob River in Tomsk Oblast

Impact of permanent dam opening on the fate of polycyclic aromatic compounds in industrial sludges accumulated on river banks: In situ approach

The impact of permanent dam opening on the fate of organic contaminants was studied in the specific case of the Orne River industrial deposits. In the downstream part of the Orne River, the river banks were mainly constituted of steelmaking wastes accumulated for decades. Coring was performed before and after the permanent dam opening (performed in November 2019). The core layers were analysed for grain size, element content, mineralogy and PAC concentrations and distributions. The fine grain size, the high iron content (20–35 %), the presence of high temperature iron phases, the high zinc and lead contents were the main characteristics of these steelmaking sludges and came along with high polycyclic aromatic hydrocarbon (PAH) concentrations. The relative enrichment in low molecular weight PAHs associated to the abundance of furans signed the contribution of coal tar in specific layers. Element and grain size results revealed the erosion of about 12 cm of material during the first year of opening. Oxidative conditions were clearly demonstrated by the presence of gypsum along the entire length of the cores collected in 2020 and the years after. Comparing PAC features in the cores collected before and after dam opening, PAH concentrations did not show significant variations, but the molecular distribution of PACs presented significant changes, mainly in the first 30 cm. Indeed, the depletion of oxygenated PACs suggested the preferential leaching of these polar molecules. Leaching might have been enhanced by opening circumstances and/or the intense flood occurring few months after dam opening. Several PAC ratios were used to confirm the leaching and oxidative processes.

The influence of vortex flow generated by spur dikes on the distribution and mixing of dissolved oxygen at a wide-shallow confluence

The inflow of heavy polluted tributaries is one of the main factors that destroy the water quality at the river confluence area and downstream, especially in the wide-shallow river confluence area. In this study, a generalized model of a two-dimensional confluence was established and validated, and dissolved oxygen concentration was used as the water quality indicator. The influence laws and mechanisms of different spur dike layout patterns on the water quality distribution characteristics and the transport and mixing processes at the confluence were explored through numerical simulation. The results show that there is a large area of water pollution at the confluence with the polluted tributary, which is distributed near the outlet of the tributary, and the water quality in this area recovers slowly. The flow ratio is the main factor affecting the distribution of water quality transport at the confluence. Arranging dikes on the opposite bank of the tributary can significantly reduce the area of pollution by adjusting the flow field. Arranging dikes on the tributary side of the confluence can effectively promote water quality mixing through vortex suction between dikes and improve water quality near the tributary side of the river bank. The dissolved oxygen concentration between dikes at the river bank on the tributary side showed an increasing trend along the river direction, and vortex flow velocity showed a decreasing trend, and the increment of dissolved oxygen concentration had a good linear correlation with the interval between dikes and the change in vortex flow velocity between dikes.

Solid waste characterization in the slum areas of Bagmati River—A case of Kathmandu, Nepal

Solid waste management (SWM) is a challenging environmental issue globally, with developing nations experiencing considerable difficulties in its efficient and effective implementation. Urban slum areas within these regions, particularly, have been reported to face unique challenges in SWM due to a combination of factors, including the low socio-economic status of residents, high population density, inadequate infrastructure, and a thriving informal economy. Despite these critical concerns, most SWM research in Nepal has concentrated on major cities and tourist hotspots. As a result, the condition of SWM in urban slum areas, typically found along the banks of major rivers in Nepal, remains a critical yet neglected aspect in research and policy discussions. This study, therefore, aims to evaluate SWM in the densely populated urban slum areas situated along the Bagmati River, a key river system in Kathmandu, the capital of Nepal. Four major slum locations within the central metropolitan area of Kathmandu—Sinamangal, Thapathali, Teku, and Balkhu—were selected for the study, and systematic random sampling and characterization of household solid waste was conducted. The results reveal that the average household solid waste generation rates in the four study sites were 155.32 g capita−1 d−1, 124.69 g capita−1 d−1, 149.9 g capita−1 d−1, and 218.44 g capita−1 d−1, respectively. Organic wastes was the most prevalent type, comprising 63.34% of the total waste, followed by paper and paper products (13.72%), plastics (12.15%), dirt and construction debris (5.57%), glass (4.31%), and other wastes (0.91%). Qualitative data from the survey revealed that although municipal waste management programs exist, awareness and participation among residents were limited. As a result, many households ended up managing their waste on their own, often in an unscientific manner polluting the river water in the vicinity. The study offers critical insights for policymakers, operators, and regulators in addressing the growing challenges of SWM. Findings are expected to aid in the sustainable management of solid waste along the river basin in central urban regions of the capital city. Under Nepal's new federal governance system, provincial and local governments are recommended to collaborate with all stakeholders, including households, to develop comprehensive, multimodal SWM strategies that also address the needs of slum areas.