River Course Research Articles

МНОГОЛЕТНЯЯ ДИНАМИКА ТРАНСГРАНИЧНОГО ПРИТОКА БИОГЕННЫХ СОЕДИНЕНИЙ ПО РЕКЕ ИЛЕ И ЕГО ТРАНСФОРМАЦИЯ ПО ТЕЧЕНИЮ РЕКИ

The paper presents the results of studies devoted to the assessment of the long-term dynamics of the volume of transboundary inflow of biogenic compounds to the territory of Kazakhstan along the Ile River. Based on long-term data from the State Monitoring of RSE «Kazhydromet,» the peculiarities of the transformation of the flow of biogenic compounds (nitrogen and phosphorus) along the river course, considering the influence of natural and anthropogenic factors, are analyzed. Information about the importance of studying biogenic substances in the formation of surface water quality, as well as river runoff’s role in the biological productivity and sanitary regime of final water bodies, is provided. The role of the transboundary flow of the Ile River as the main factor in forming the biogenic substances regime on the territory of Kazakhstan is highlighted. A quantitative assessment of the volume of average annual inflow of these compounds for the period from 2003 to 2020 is given, along with the main factors determining the transformation of nutrient runoff along the river course.

Changing soil properties influenced vegetation diversity along effluent‐dominated river courses in dry areas of north‐western India

AbstractImproving the environmental quality of effluent‐dominated seasonal rivers is a fundamental challenge for sustaining life in drylands, where people utilize contaminated water to produce food, which ultimately accumulates in the food chain. Preventing further contaminations and phytoremediation are needed to avoid environmental degradation and health risks. This study aimed at analysing water quality and its impacts on soil and vegetation at effluent‐impacted, river‐edge and non‐polluted (control) micro‐habitats at five sites along Luni, Bandi and Jojari Rivers each in western Rajasthan. Soil and water samples were collected and analysed, and vegetation was recorded. River water exhibited high pH (7.60–8.60), electrical conductivity (EC; 2.45–38.20 dS m−1), total dissolved solid (TDS; 1.26–30.86 g L−1), alkalinity (24.0–250.0 mg L−1) and Na (1.50–30.00 g L−1), K (29.0–1100.0 mg L−1), Ca (136.0–3800.0 mg L−1) and Mn (0.05–83.92 mg L−1) concentrations and low NH4‐N, NO3‐N, PO4‐P and heavy metals. Species numbers ranged between 32 along Luni and 20 along Jojari. Soil pH, EC, PO4‐P and shrub richness (R), diversity (H′) and evenness (e') were highest for Bandi, whereas NH4‐N, NO3‐N, K and tree R and H′ were highest for Jojari River. Soil variables decreased and plant diversity increased downstream. Concentrations of Cd, Zn, Cr, Cu and Pb were above the acceptable limit in leaf of Salvadora persica and Prosopis juliflora. Principal component analysis (PCA) revealed significant relationships between different variables of river water, soil, and vegetation and 11 PCA axes. Conclusively, industry effluents negatively affected water, soil and river ecology. Effluent‐impacted soils had high salinity and less diversity adapted by salt‐tolerant species, complementary effects of which contribute to restoring the modified ecosystem and urban greening. Although people utilize effluent‐contaminated water in irrigation, precautions should be taken to avoid environmental and animal/human health risks.

New Drag Force Formula of Bending Stems in Deriving Analytical Solutions of Velocity Profile for Flow Through Flexible Vegetation

AbstractInvestigations of water flow movements affected by vegetation is a research hotspot in vegetation ecological restoration. The theory and equations of the flow velocity distribution under the influence of rigid vegetation are relatively mature. This study proposes a new drag force equation that varies with the vegetation bending angle and a new analytical solution of the velocity profile. Comparisons between the model calculation and experimental data, results showed that this new proposed model produced accurate simulations for flow through flexible vegetation for various deflections. In addition, this analytical model was verified to be applicable to rigid vegetation without a bending angle. Moreover, the features of the parameters adopted in this analytical equation are discussed, and the empirical equation for these parameters are presented. This study further improves the research in the field of environmental fluid mechanics and can serve as a theoretical underpinning for the ecological restoration of river courses.

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

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

Fish diversity, fishing gears and their catch in the upper Matamuhury river of southeastern Bangladesh

Finfish richness, their abundance, fishing gears and their catch in the upper Matamuhuri river were studied from January to December 2022 along the river course at hilly upstream of Bandarban Hill District. A total of 95 freshwater finfish species under 69 genera belonging to 36 families under 14 orders were recorded in this mountainous section of this river. Maximum number of species were recorded under the Family Cyprinidae (19 species) followed by Danionidae (11 species) and Bagridae (7 species). Amongst 95 finfish species 11 belonged to ‘endangered’ and 12 to ‘vulnerable’ category of threatened species and four were data deficient (e.g. Barilius barila, Balitora brucei, Eleotris lutea and Oryzias dancena) according to IUCN conservation status. Neolissochilus sp. and Golden Mahashol (Tor puttitora) are reported for the first time from the upstream of Matamuhuri River. A systematic list of recorded finfish with their English names, local names, abundance and conservation status is presented. Under eight categories, 16 types of fishing gears and their catch were documented of which two types of gears (Large push net - Haddi Jal and Bowl trap - Bati Trap) were new and not reported elsewhere earlier. Biodivers. Conserv. Bioresour. Manag. 2024, 10(1): 15-28

Incision and rock uplift along the Lower Seine River since Marine Isotope Stage 8

ABSTRACTThe study of alluvial terraces helps in reconstructing the past geometries of rivers and makes it possible to assess the rate and pattern of fluvial incision and bedrock uplift. The fluctuations of river base levels are particularly variable and complex during the Late Quaternary in the lower course of rivers due to the interplay of responses to sea‐level fluctuations, tectonics and glacio‐isostasy. In this paper, the geometry and chronology of Manoir Brésil, an outcrop of alluvial terraces of the Lower Seine River, northern France, are investigated through a multidisciplinary study. Fluvial incision during MIS 8 in the Lower Seine in relation to sea‐level drop is recorded by an erosional surface cut into the chalk bedrock. This surface is covered by MIS 7 tidal deposits and then by younger, mostly periglacial colluvium (head). Manoir Brésil is therefore considered to be a chronological equivalent of the nearby, well‐studied Tourville‐la‐Rivière outcrop. The deposits are affected by post‐MIS 7 cryoturbation processes. Based on the local elevation of MIS 7 tidal deposits and erosional surfaces at Manoir Brésil, a minimum bedrock uplift rate of 25–40 m/Ma and an erosion rate of 125 m/Ma during glacial periods can be proposed. A regional correlation of the MIS 8 erosional surface is increasingly deformed by uplift towards the North, making it difficult to correlate the fluvial deposits along the Seine without precise chronological control. We interpret this regional tilt as the result of isostasy rebound after glaciations, consistent with the distribution of the elevations of MIS 5e and MIS 7 marine deposits along the English Channel.

THE ECOLOGICAL ASSESSMENT OF SMALL RIVERS IN UKRAINE UNDER CONDITIONS OF INTENSIVE WAR IMPACT

Aquatic ecosystems are perpetually exposed to anthropogenic sources of pollution, wherein the quality of subterranean and surface waters undergoes influence from both natural and anthropogenic processes. This interaction results in environmental predicaments and, occasionally, environmental crises. Small rivers, in particular, bear a pronounced impact from human interventions on the environment. The investigation undertaken by the researchers commenced in 2021 with the primary objective of scrutinizing the ecological condition of the Irsha River. Regrettably, due to the military aggression of the Russian Federation, the regions through which the river courses were temporarily occupied, subjecting it to considerable anthropogenic disturbances. Specifically, two bridges spanning the Irsha River in the Malyn area were demolished, and military operations transpired along the riverbanks, leading to the accumulation of damaged military equipment. Consequently, it was deemed imperative during the course of our study to conduct an analysis of the natural water in the Irsha River subsequent to the military activities. The outcomes of a comprehensive assessment of surface water quality, employing a graphical method, revealed that, during the period of 2021-2022, the river waters within the Irsha River exhibited an overall failure to meet quality standards in both monitoring locations. Elevated values of Maximum Permissible Concentration (MPC) exceeding the norm were noted for the Chemical Oxygen Demand (COD) indicator, the dissolved oxygen indicator, as well as the general iron and iron of permanganate oxidizability parameters in both samples. The highest degree of pollution was discerned in the Malyn Reservoir, whereas the Irsha Reservoir manifested comparatively lower pollution levels in the aquatic environment.

Lake Wellington and West Walker River in Great Basin of western United States: History and genesis

ABSTRACTClosed basins within the Great Basin of the western United States were home to numerous lakes during the Pleistocene. One of these paleolakes along the western edge of the Great Basin, Lake Wellington, once filled a 10 × 25‐km expanse of Smith Valley to depths approaching 90 m. This and other lakes that existed during the Pleistocene are generally considered to be pluvial, indicating contemporaneity with either or all a period of cooler climate, increased rainfall and snowmelt, and relatively reduced rates of evaporation as compared to today. Here we combine the results of 36Cl terrestrial cosmogenic nuclide surface exposure dating with soils and geomorphic observations to suggest Lake Wellington was not a pluvial lake but instead the result of a large landslide prior to ~43 ± 15 ka along the West Walker River where it exited Smith Valley. The observations collected also reveal an ancestral course of the West Walker River ~85 m above the current river grade. Attributing the elevation difference to incision caused by active 0.05 ± 0.01 mm a−1 uplift of the underlying Singatse and assuming the ancestral course followed the same path as today places the age of the paleoriver course at ~1.7 Ma.

A new rare catfish species from southeastern Brazil provides insights into the origins of similar colour patterns in syntopic, distantly related mountain trichomycterines (Siluriformes, Trichomycteridae)

Colour patterns are diverse in trichomycterine catfishes and are often used to diagnose species. Here, we analyse the first case of adults of two syntopic species of Trichomycterus sharing nearly identical colour patterns: a rare new species of the subgenus Paracambeva and Trichomycterus maculosus, a distantly related species of the subgenus Trichomycterus. Both species are endemic to the upper Rio Paraíba do Sul basin (RPSB), which had a different course until the Tertiary period and is situated within the Southeastern Brazilian Continental Rift, mostly active in the Eocene-Oligocene. A time-calibrated multigene analysis, 3144 bp, supported the new species as sister to Trichomycterus itatiayae, both comprising a lineage with Middle Miocene age, when that colour pattern would have first arisen. The new species is diagnosed by characters from the latero-sensory system and bone morphology. Our results, combined with available biogeographical data, indicated the colour pattern of T. maculosus arising in the Late Pliocene, following the dispersal of its group to the upper RPSB after river course changing. Two hypotheses for the independent origin of the same colour pattern are discussed. First, a case of evolutionary convergence for adaptation to live on a similarly coloured gravel substrate, giving some cryptic advantage against predators. Second, mimetic association through anti-predation features. In the latter case, although trichomycterids lack fin spines to inoculate venom as in other catfishes, the species here studied have a supposed axillary gland above the pectoral fin, just posterior to the opercular odontodes, but with properties and functions still unknown.

Evaluating the impact of porcupine systems in the flow field of the river: a hydrodynamic model study

ABSTRACT Riverbank and in-stream protection are crucial in numerous river stretches, where erosion of banks and bed material instigates river course alterations, consequently leading to land and property damage. In large Indian braided rivers like Brahmaputra, implementing tetrahedron frames commonly referred to as ‘porcupines’ has emerged as a cost-effective strategy for river training, yielding commendable outcomes in near bank sedimentation. Using flexible river training structures, such as porcupine, presents an appealing option for managing braided river channel networks in areas where permanent control structures like groynes or dams prove excessively costly or potentially ineffective, particularly in systems exhibiting highly dynamic flow regimes and morphology. This work aims to develop a hydrodynamic model that integrates the porcupine systems within its framework. The model’s effectiveness was assessed through a field test near Nematighat, Brahmaputra River, in collaboration with Assam’s Water Resources Department. The mathematical modelling provided some valuable insights regarding the flow characteristics surrounding the porcupine structure, shedding light on its hydrodynamic behaviour.

Potential of Agroforestry Practices in Multifunctional Landscapes for Enhancing the Livelihoods of Local Dwellers in the North-Western Charlands of Bangladesh

Char is any accretion in a river course that extends or establishes new land. A well-planned integrated land-use system combining woody perennials (agroforestry) can ensure sustainable, environmentally friendly climate resilience land-use systems and livelihood options on charland. To date, no systemic investigation of charland land agroforestry has been undertaken. A comprehensive study of the potential of agroforestry systems in charland areas was conducted using qualitative and quantitative methodologies. Two methods were employed: structured questionnaire interviews and botanical surveys. Findings revealed that considerable variation exists in both charland and mainland areas in terms of socio-demographic characteristics. Both tree and agroforestry knowledge of mainland farmers is greater than that of charland farmers. Charland dwellers sell almost all their farm products, while most mainland farmers consume their products. Agroforestry-related communication between extension workers and farmers is limited in both ecosystems. However, farmer interaction with extension workers is far less common in charland areas. Mainland farmers are satisfied with their homestead production systems, whereas cha land farmers face huge problems with the free grazing of cattle and goats. Mainland farmers think quality planting materials and fencing systems are key issues. Leafy short-rotation vegetables and climbing vegetables are more common in charlands. Other common marketable vegetables are tomato, brinjal, carrot, cauliflower, and cabbage. All fruit trees common on charland are more frequently found in the mainland areas. In the case of timber, eucalyptus (Eucalyptus camaldulensis) is more common on charland, whereas mahogany (Swietenia macrophylla) frequency is higher in the mainland. Medicinal trees are uncommon in both ecosystems except for neem (Azadirachta indica). Through proper training and motivation of farmers, there is a vast scope to increase tree and vegetable diversity in charland farms.

Environmental impact of the vibration generated by the underwater shaking table of the National Facility for Earthquake Engineering Simulation (NFEES)

Earthquake simulation shaking tables serve as the valuable tools for investigating the seismic performance of structures, yet they can generate excessive vibrations in surrounding environments during operation. The National Facility for Earthquake Engineering Simulation (NFEES) in China, which is currently in the commissioning phase, will be the world's largest earthquake simulation research facility. Its experimental center consists of a 16 m × 16 m shaking table and two 6 m × 6 m underwater shaking tables (one movable). This study aims to investigate the environmental impact of the vibration generated by the fixed underwater shaking table. Initially, the vibrations of the surrounding ground, shaking table foundations, and adjacent simulation center are tested using the sinusoidal full-load and full-acceleration excitations generated by the shaking table. Upon analyzing the test results, it is observed that the peak ground acceleration (PGA) in the short side direction of foundation attenuates rapidly for high-frequency loading, with a maximum acceleration attenuation up to 55.95 % at distances of 0 m–20 m. The maximum acceleration of the foundation occurs at the edge of the shaking table and significant differences in acceleration are observed at various points across the foundation. The VLZmax of the simulation center is 66.85 dB, which is lower than the limit requirements of the Chinese standard GB55016. Subsequently, an overall finite element model of the surrounding soil-shaking table foundations-adjacent simulation center is established. Following the validation of the numerical model, the vibration isolation efficiency of the adjacent river course and the foundation isolation joint that separates the large shaking table foundation from the underwater shaking table foundation are assessed. Compared to the test results, numerical results show relatively minor discrepancies in the peak acceleration of the ground and the foundation, with maximum errors of 24.59 % and 21.11 %, respectively. The river course and the foundation isolation joint demonstrate better vibration isolation performance for short-wavelength waves, with a maximum vibration isolation efficiency reaching 64.71 % and 63.56 %, respectively.

Environmental Deterioration of Damodar River, West Bengal

Among a few scattered forest patches in Damodar valley, the forest covering the entire Susunia Hills is important for its species diversity of floral assemblages. Along the river course of Damodar, the main industrial area of West Bengal has developed. Though the sewage effluent from such industries empties into the Damodar River after treatment, the water of Damodar River is unfit for use even for outdoor bathing due to the presence of faecal coliform bacteria and higher values of biochemical oxygen demand in the river water exceeding the permissible limit. Damodar river water is probably polluted by the mixing of the surface runoffs from the non-point sources.

High diversity of macrophytes in the »green river« Krka (Slovenia)

AbstractThe presence, abundance, and distribution of aquatic macrophytes and their growth forms in the river Krka in Slovenia were studied. The studied slow‐flowing lowland River Krka is also called a »green river« since it is overgrown with macrophytes from its source to its outflow to the river Sava. The environmental parameters of the river ecosystem were also assessed using the modified version of the RCE (Riparian, Channel, and Environmental Inventory) method. Within 24 sections reaching from 100 to 250 m, 23 taxa of macrophytes were found. Sections were distributed noncontinuously from the source to the outflow more or less equally along the river course. The invasive alien species Elodea canadensis reached the highest relative abundance, followed by Ranunculus trichophyllus, Potamogeton crispus, Myriophyllum spicatum, Ceratophyllum demersum, and Potamogeton nodosus. Potamogeton crispus was present in most of the studied sections followed by Nasturtium officinale and M. spicatum. The river offers suitable conditions for the high diversity of macrophytes regarding the type of substrate, low flow velocity, heterogeneity of habitats, and relatively high concentrations of nutrients. In comparison to the survey performed in 2003, when the river Krka was surveyed continuously from the source to the outflow, we found that seven of the submerged and natant macrophytes were not detected in 2020. Macrophytes, growing in the river Krka, indicated meso‐ to eutrophic conditions. Five species recorded in the river Krka are listed on the Red list of endangered species in Slovenia, indicating the need to conserve the river ecosystem.

Landscape modelling of the Yalong River catchment during the uplift of Southeast Tibet

Southeast Tibet is characterized by low-relief surfaces at high-elevation, showing very little exhumation during the India–Asia collision, as well as deeply incised rivers valleys. Understanding how these low-relief surfaces adjacent to the plateau's edge survived from regressive fluvial erosion is still an enigma, which is key to understanding the formation of the plateau. In the Three Rivers Region around the Eastern Himalayan Syntaxis, the squeezing of the Salween, Mekong and Yangtze rivers’ drainage basins in their middlestream, where numerous thrusts parallel to the river channels are observed, has been invoked as the key factor driving the river evolution. More to the east, in the Great Bends Region, no such squeezing of the drainage basins has been observed; the Yalong and Yangtze rivers flow perpendicularly across northeast-trending thrust belts, generating huge (>100 km) river course bends with steep channel slopes. These faults have significantly contributed to construct the high plateau margin, including the Yalong Thrust Belt (YTB), active during the Eocene (∼35–25 Ma) and reactivated in the Miocene (15–12 Ma). By applying state-of-the-art landscape modelling (FastScape) to the Yalong River catchment, with simplified rock uplift scenario deduced from fault activities, we show that strong monsoonal precipitation on the plateau (∼1 m/yr), even during only a short period such as the Mid–Miocene Climatic Optimum (17–14 Ma), produces wide rivers and destroys the plateau edge. In contrast, modelling the orographic effect with weak net precipitation (∼0.2 m/yr) above ∼2700 or 4000 m, preserves the plateau edge and reproduces the slope of the Yalong River, but with a width larger than in nature. To reproduce both the slope and narrowness of the Yalong gorge just upstream of the YTB, a combination of a rapid Miocene rock uplift leading to a regional surface uplift, which creates a significant orographic effect and preserves interfluve low-relief surfaces close to the plateau edge, and a water inflow in upstream, which deeply incises downstream river valleys, is necessary. Such an amount of upstream water is collected from the flat and expansive headwater, inherited from the inland endorheic zone of the plateau interior, on which the hillslope processes dominate the landscape evolution.

Morphometric Characteristics of the Lower Orashi River, Niger Delta Region, Nigeria

The study examined the spatial analysis of the morphometric characteristics of the Lower Orashi River, Niger Delta Region, Nigeria. The river course was segmented into 30 equal distances of 4.8m from each other and at each point, the morphometric parameters like width, depth, and flow velocity. The discharge was measured from these parameters. Descriptive and inferential statistics were employed for data analysis while results are presented using tables and graphs. Results showed that width of the river ranged from 77.90m to 2788.00m with the mean width of 318.83m. The depth ranged from 2.10 to 7.60m with the mean depth recording 4.14m as it was higher at the upper section of the river while it becomes lower as it is entering the Atlantic Ocean. Furthermore, width was significantly correlated with the depth (r= -0.556, p<0.05), cross sectional area (r= 0.989, p<0.05) and discharge (r= 0.987, p<0.05). Also, elevation was significantly correlated with cross sectional area (r= -0.506, p<0.05) and discharge (r = -0.511, p<0.05). More importantly, the cross sectional area was correlated with discharge (r=0.995, p<0.05). The study concluded that there is significant variation existing in the morphometric parameters namely width, elevation, cross sectional area and discharge among the segments along Orashi River. The study therefore recommended that the water course should be reduced of human activities to reduce the rate of soil loss or discharge and to boost the river floor with adequate morphological property.

Evaluation of the Cipalabuan River's water quality and measures for reducing water pollution in the Sukabumi Regency

The Cipalabuan River serves as an ecosystem that provides habitat for many species and as a source of water for industry, agriculture, and drinking. However, growing industrial and residential activity poses a threat to the amount and quality of river water. The river has recently contributed to both liquid and solid waste, which has lowered the quality of the river's water. The Cipalabuan River flows through the city center from upstream to downstream, collecting pollutants from the discharge of local activities along the river's course, including liquid and solid waste. By monitoring and computing the water's quality at a certain location and time, this study seeks to ascertain the current state of water quality. In order to create a sequential explanatory design, a mixed method approach was used, mixing quantitative and qualitative methodologies in parallel. Water quality in the Cipalabuan River is influenced by a number of factors, including the actions of those who use the river as a disposal site, public ignorance of the need to control pollution, competing interests in the management of water resources, and a lack of cooperation between authorized agencies in the management of natural resources and the control of water pollution.

Fluvio-geomorphic change of the Padma-Meghna river course using the NDWI and MNDWI techniques

ABSTRACT This study intends to investigate the fluvial-geomorphic change and erosion-accretion processes of two significant rivers. The 2149 km2 research area’s overall erosion and accretion were depicted using multi-temporal Landsat images and Normalized Difference Water Index, Modified Normalized Difference Water Index methods to measure and investigate change. However, focus has been placed on four unique sections that are prone to erosion, and the bank migration of the section has been measured in order to depict the actual state of erosion. The Padma-Meghna River eroded approximately 11.0, 77.0, and 13.0 km2 between 1973–1978, 1978–1989, and 1989–1994. However, 78.0 and 48.0 km2 of accretion occurred in the years between 1994 and 1999 and 1999 and 2004. Moreover, between 2004 and 2021, the river’s erosional activity was remarkably dynamic compared to deposition. Besides, 64 km2 and 4 km2 of land accretion occurred during 2008–2014 and 2014–2019, while 77 km2 and 68 km2 of land eroded during 2004–2008 and 2019–2021. The overall rates of erosion and accretion are 5.12% and 4.04%, respectively. Statistically, both banks of the Padma River eroded about 2 km from 1973 to 2021. Padma-Meghna confluences are more unstable and susceptible to change. The Meghna’s left bank moved 4.5 km east between Goshairhat and Haimchar in 1989, and in 2008, the river shifted 4.8 km west from the river of 1994. In 1989, it moved 5 km east from a previous location between Goshairhat and Haiderganj, and in 2008, it moved 6.3 km west from the 1989 river. The bank migrated 12 km eastward in 2014 from where it was in 2008 through the bar development. The Mehendiganj Upazila’s eastern side lost more than 7.4 km between 1973 and 2021, and the current major channel is simply 7.4 km west of the 1973 river. The findings of the dynamic changes might be useful to planners, developers, researchers, and government agencies as they develop and put into practice new development initiatives and river basin management.

Tectonic geomorphology and Quaternary slip history of the Fuyun fault, southwestern Altai Mountains, central Asia

The northwest-trending Altai Mountains of central Asia expose a complex network of thrust and strike-slip faults that are key features accommodating intracontinental crustal shortening related to the Cenozoic India-Asia collision. In this study, we investigated the Quaternary slip history of the Fuyun fault, a right-lateral strike-slip fault bounding the southwestern margin of the Altai Mountains, through geologic mapping, geomorphic surveying, and optically stimulated luminescence (OSL) geochronology. At the Kuoyibagaer site, the Fuyun fault displaces three generations of Pleistocene–Holocene fill-cut river terraces (i.e., T3, T2, and T1) containing landslide and debris-flow deposits. The right-lateral offsets are magnified by erosion of terrace risers, suggesting that river course migration has been faster than slip along the Fuyun fault. The highest Tp2 terrace was abandoned in the middle Pleistocene (150.4 ± 8.1 ka uppermost OSL age) and was displaced 145.5 +45.6/–12.1 m along the Fuyun fault, yielding a slip rate of 1.0 +0.4/–0.1 mm/yr since the middle Pleistocene. The lower Tp1 terrace was abandoned in the late Pleistocene and aggraded by landslides and debris flows in the latest Pleistocene–Holocene (36.7 ± 1.6 ka uppermost OSL age). Tp1 was displaced 67.5 +14.2/–6.1 m along the Fuyun fault, yielding a slip rate of 1.8 +0.5/–0.2 mm/yr since the late Pleistocene. Our preferred minimum slip rate of ~1 mm/yr suggests the Fuyun fault accommodates ~16% of the average geodetic velocity of ~6 mm/yr across the Altai Mountains. Integration of our new Fuyun slip rate with other published fault slip rates accounts for ~4.2 mm/yr of convergence across the Chinese Altai, or ~70% of the geodetic velocity field.

Reintroducing Atlantic salmon in the river Rhine for decades: Why did it not result in the return of a viable population?

AbstractFreshwater species biodiversity is under threat. The average global decline for migratory fish species is estimated to be more than 75% since 1970. Atlantic salmon is one of these species with a steep decline in north‐western Europe and it even went extinct in the river Rhine in the 1950s. The causes for this decline have been posted to habitat loss, pollution, climate change and overfishing. Annual stocking in the Rhine since the late 1980s resulted in an initial increase in the Atlantic salmon numbers after which numbers collapsed again. In this paper, we lay out the recent decline, estimate losses of smolts and adults at different sections in the freshwater habitat and elaborate on potential causes of the recent decline and these losses. We found that the salmon population of the river Rhine has declined rapidly over the past two decades, with a current estimated spawning population of only ~350–800 individuals. The percentage of salmon smolts returning as adults to spawning grounds is estimated at 0.5%–0.6%, well below the 3% supposedly needed to maintain a self‐sustaining population. Many individuals disappear during their migrations, with the highest percentage of smolts disappearing in the German tributaries (44%) and the Dutch lower Rhine (71%), while the percentage of disappearing adults is highest in both the Dutch (74%) and the German (78%) Rhine. Causes for the losses per river section remain unclear and possible threats, some specific to the river Rhine, are being discussed. The large losses of smolts and adults in inland waters, compared with open sea losses, indicate that restocking the river Rhine might only result in a self‐sustaining population with more ecological restoration than carried out so far along the intensively shipped and highly regulated river course and associated high levels of predation, and might be increasingly limited by future climate change.