Quiet Water Research Articles

The Ballynoe Stratiform Barite Deposit, Silvermines, County Tipperary, Ireland

The Ballynoe barite deposit is a conformable, mineralised horizon of Lower Carboniferous age overlying a diastem and mass faunal extinction demarking the transition from a quiet water environment to one of dynamic sedimentation. The geometry of the barite orebody correlates with the palaeotopography of the footwall, which acted as an important control over the lateral extent, thickness, and nature of the mineralisation. Sedimentary features within the barite horizon suggest that it was precipitated in the form of a cryptocrystalline mud which underwent major diagenetic modification resulting in extensive stylolitisation, recrystallisation, and remobilisation. There is abundant and compelling geological and isotopic evidence for early local exhalation from the presence of a hydrothermal vent fauna consisting of delicately pyritised worm tubes and haematised filaments of apparent microbial origin. The worm tubes are remarkably similar to examples from modern and ancient volcanic-hosted massive sulphide deposits, and the filamentous microfossils have similarities to modern Fe-oxidising bacteria. Strontium in the barite has an 87Sr/86Sr ratio indistinguishable from seawater between 350 and 344 Ma whilst oxygen isotopes from barite and chert suggest a diagenetic origin in equilibrium with such seawater around 60–70 °C. Fluid inclusion studies have shown that, in general, low temperature inclusions are very saline (20%–25%) whilst at higher homogenisation temperatures they are more dilute (9%–12%).

Geochemical and Biostratigraphical Evaluation of Lokpanta Shale in Abakaliki Anticlinorium, Anambra Basin Province, Southeast Nigeria

A geochemical and biostratigraphic method has been applied to explore the quality of organic matter, thermal evolution, potential hydrocarbon source and type of fossils of Lokpanta Shale from the Abakaliki Anticlinorium, Anambra Basin Province, Southeast Nigeria. Data obtained reveal that the total organic carbon (TOC) (2.18wt%) of the shale constitutes that of good to excellent source rock with gas-prone kerogen indicated by Rock-Eval S2/S3 (2.32). The low oxygen index (OI) (27.20 mgCO2g-1TOC) suggest deposition under low energy environments. The plots of HI against Tmax classified the organic matter as Type III kerogen. The poor concentration of OM is thought to account for its current hydrogen index (31.47 mgHCg-1TOC). The predominance of Type III kerogen in the Lokpanta shale suggests their potential to generate gas in the deeply buried sections. The Tmax values from the pyrolysis of the shales of the Lokpanta ranges from 428 to 442oC corresponding to maturity levels within the oil formation. The lamination of the sediments of the Lokpanta area with no burrows and the occurrence of dominantly planktonic foraminiferal assemblages also indicate a quiet water anoxic marine condition.

The deep-water, high-diversity Edgewood-Cathay brachiopod Fauna and its Hirnantian counterpart

The last phase of the end-Ordovician extinction event involved substantial sea-level changes. The Oslo/Asker District in Norway is a rare place where the deeper-water early Hirnantian fauna is succeeded by the equivalent deeper-water Edgewood-Cathay Fauna. Both faunas are highly diverse, with the same small-shelled brachiopods, Onniella, Leangella, and Eoplectodonta, dominating. They also share a large number of long-ranging and eurytopic genera. Taxa from contemporary shallower-water environments are rare. Near a third of the brachiopod genera in the Norwegian deeper-water early Hirnantian Fauna went extinct, including seven genera that survived into the Ordovician/Silurian boundary strata. Deeper-water early Hirnatian and Edgewood-Cathay collections are not well-known worldwide. Global quantitative samples from low latitudes, including the Norwegian samples, were compared against each other using NMDS (Non-metric Multidimensional Scaling) with the Bray-Curtis index. Qualitative samples used NMDS with the Raup-Crick index and Network Analysis. The Raup-Crick index sharply differentiated the early Hirnantian and Edgewood-Cathay faunas, possibly due to sensitivity to extinction and origination data. In contrast, the paleogeographic affinity between collections of the two faunas is pronounced using the Bray-Curtis index. Network Analysis also demonstrates regionality; the Edgewood-Cathay Fauna is especially heterogeneous. This contrasts with the shallower-water Hirnantia Fauna, which is more cosmopolitan. Quiet waters below the storm-wave base possibly hindered the spread of larvae, and anoxic plumes of water may have caused further barriers to the lateral spreading of the Edgewood-Cathay Fauna. As in Norway, long-ranging, eurytopic taxa were shared between the two faunas with few typical shallow-water taxa.

Non-pollen palynomorph assemblages in mid- to late Holocene wetland deposits and their palaeoenvironments of deposition: Microfossil signatures in sediment sequences of the Yangtze Delta coastal lowlands, East China

Fluvial processes such as sediment deposition within drainage channels and seasonal overbank flooding, and fluvial events such as occasional high intensity floods all leave particular sedimentary signatures in terms of their lithology and also in their contained microfossil assemblages, which represent different environments of deposition. Over several thousand years the Yangtze River in eastern China has developed a coastal lowland plain around its delta that is mainly composed of stacked fluvial sediment facies, but also includes many marine or estuarine layers in some areas, as well as deposits of limnic and semi-terrestrial pool, marsh and mire origin, some of which are highly organic. The fluvial facies are dominantly clastic sequences of sands, silts and clays that reflect a range of deposition from quiet water to high energy conditions and in varying water depths, mainly governed by fluvial input from the Yangtze and the many other, smaller, rivers and streams of the deltaic lowland. The limnic and marshland sediments reflect autochthonous deposition in a range of freshwater wetland types of varying water depth, from lake through marsh/fen to surface peatland. Allied to lithological and pollen data, non-pollen palynomorph spore assemblages and abundances within these complex sedimentary sequences, particularly from algal communities, provide signatures of floodplain wetland depositional history and hydrodynamic patterns. We have used groupings of these microfossil data to characterise the sedimentary facies of the lower Yangtze coastal plain and to reconstruct hydrological history across the area at a range of spatial scales. Fluctuations in the relative taxa abundances are good indicators of changes in water levels at the site scale from surface waterlogging through reedswamp and fen to deeper open water. While some changes seem to be site specific, the data show flooding and increased water depths that correlate with known phases of climatic deterioration.

Survival Strategies of Duckweeds, the World's Smallest Angiosperms.

Duckweeds (Lemnaceae) are small, simply constructed aquatic higher plants that grow on or just below the surface of quiet waters. They consist primarily of leaf-like assimilatory organs, or fronds, that reproduce mainly by vegetative replication. Despite their diminutive size and inornate habit, duckweeds have been able to colonize and maintain themselves in almost all of the world's climate zones. They are thereby subject to multiple adverse influences during the growing season, such as high temperatures, extremes of light intensity and pH, nutrient shortage, damage by microorganisms and herbivores, the presence of harmful substances in the water, and competition from other aquatic plants, and they must also be able to withstand winter cold and drought that can be lethal to the fronds. This review discusses the means by which duckweeds come to grips with these adverse influences to ensure their survival. Important duckweed attributes in this regard are a pronounced potential for rapid growth and frond replication, a juvenile developmental status facilitating adventitious organ formation, and clonal diversity. Duckweeds have specific features at their disposal for coping with particular environmental difficulties and can also cooperate with other organisms of their surroundings to improve their survival chances.

Grain size trend analysis for sediment characteristic of Cirebon Waters

This research aims to understand the sediment characteristic of Cirebon waters using a grain size trend analysis (GSTA). The GSTA can be used to determine sediment physical characteristics and demonstrate the sedimentary processes. A total of 32 seabed surface sediments were analyzed by measuring the size of sedimentary grains using the Mastersizer 2000 instrument and calculating grain size parameters such as mean grain size, sorting, skewness, and kurtosis using geometric methods in the Gradistat program. Analysis of grain size showed that sediments in the Cirebon Waters are dominated by silt with ranges from 7.765 to 33.43 µm (very coarse to fine silt). The mean grain size and skewness values indicated an increase in current energy and sediment transport rate from the southwest to the northeast part of Cirebon Waters. Sediments are poorly sorted, and kurtosis is predominantly mesokurtic type. All sediments were deposited by deposition mechanism in pelagic suspension and affected by slow deposition from quiet waters. Granulometric analyses become a good proxy to give fundamental information on sediment dynamics.

Free-surface undulation and velocity turbulence in shallow undular hydraulic jumps

Undular hydraulic jumps and bores occur in coastal and estuarial regions at small approach Froude numbers and introduce non-uniform evolution of hydraulic properties in the flow direction, affecting the transport and deposition of sediment and other materials. This paper reports an experimental study of relatively wide undular hydraulic jumps generated in a 1.4-m-wide flume, characterized by inflow aspect ratio less than 0.06 and no lateral shockwave crossing at the first standing wave crest. General free-surface shape observations were conducted for a range of Froude numbers between 1.5 and 2.9 and Reynolds numbers between 2.5 × 104 and 1.2 × 105, while detailed free-surface and velocity measurements were performed at longitudinal and transverse cross-sections using acoustic displacement meters (ADMs) and an acoustic Doppler velocimeter (ADV), at five Froude numbers from 1.5 to 1.9. The results highlight complicated relationship of the three-dimensional free-surface characteristics with the variation of Froude number, which exhibits different features at the first two waves and at other sequent waves. The velocity data highlighted unique features of turbulent velocity redistribution at the first wave, including the distributions of turbulence intensity and Reynolds shear stresses. Particular focus on the formation of a “quiet water” zone below the upward-deflected mainstream flow was reported, with presence of instantaneous reversing velocities above the channel bed. The flow pattern analysis was facilitated with mean vorticity characterization. The results reflect that the evolution of undular hydraulic jump with increasing Froude number is a process of gradual turbulence localization towards the first standing wave, and the transition to a breaking hydraulic jump is achieved by the formation of a surface roller at the steepened jump front overwhelming the “resistance” of the bottom “quiet water” zone and forcing a change in the main flow path.

Application of Parameterized Grain-Size Endmember Modeling in the Study of Quaternary Oxbow Lake Sedimentation: A Case Study of Tövises Bed Sediments in the Eastern Great Hungarian Plain

Abandoned channels are essential in the Quaternary floodplains, and their infill contains different paleoenvironment recorders. Grain-size distribution (GSD) is one proxy that helps characterize the alluviation and associated sedimentological processes of the abandoned channels. The classic statistical methods of the grain-size analysis provide insufficient information on the whole distribution; this necessitates a more comprehensive approach. Grain-size endmember modeling (EMM) is one approach beyond the traditional procedures that helps unmix the GSDs. This study describes the changes in the depositional process by unmixing the GSDs of a Holocene abandoned channel through parameterized EMM integrated with lithofacies, age–depth model, loss-on-ignition (LOI), and magnetic susceptibility (MS). This approach effectively enabled the quantification and characterization of up to four endmembers (EM1-4); the characteristics of grain-size endmembers imply changes in sedimentary environments since 8000 BP. EM1 is mainly clay and very fine silt, representing the fine component of the distribution corresponding to the background of quiet water sedimentation of the lacustrine phase. EM2 and EM3 are the intermediate components representing the distal overbank deposits of the flood. EM4 is dominated by coarse silt and very fine sand, representing deposition of overbank flow during the flood periods. This paper demonstrates that the parametrized grain-size EMM is reasonable in characterizing abandoned channel infill sedimentary depositional and sedimentation history.

GNSS-RO Deep Refraction Signals from Moist Marine Atmospheric Boundary Layer (MABL)

The marine atmospheric boundary layer (MABL) has a profound impact on sensible heat and moisture exchanges between the surface and the free troposphere. The goal of this study is to develop an alternative technique for retrieving MABL-specific humidity (q) using GNSS-RO data in deep-refracted signals. The GNSS-RO signal amplitude (i.e., signal-to-noise ratio or SNR) at the deep straight-line height (HSL) was been found to be strongly impacted by water vapor within the MABL. This study presents a statistical analysis to empirically relate the normalized SNR (SRO) at deep HSL to the MABL q at 950 hPa (~400 m). When compared to the ERA5 reanalysis data, a good linear q–SRO relationship is found with the deep HSL SRO data, but careful treatments of receiver noise, SNR normalization, and receiver orbital altitude are required. We attribute the good q–SRO correlation to the strong refraction from a uniform, horizontally stratiform and dynamically quiet MABL water vapor layer. Ducting and diffraction/interference by this layer help to enhance the SRO amplitude at deep HSL. Potential MABL water vapor retrieval can be further developed to take advantage of a higher number of SRO measurements in the MABL compared to the Level-2 products. A better sampled diurnal variation of the MABL q is demonstrated with the SRO data over the Southeast Pacific (SEP) and the Northeast Pacific (NEP) regions, which appear to be consistent with the low cloud amount variations reported in previous studies.

Bivalves in the upper Miocene reef complex of Mallorca, Spain

Bivalves are common components in all the palaeoenvironments recognised in the Llucmajor Platform, the best-known outcrop of the Upper Miocene Mallorca Reef Complex. Shell concentrations of autochthonous elements with a low degree of taphonomical modification accumulated on the deep, quiet water bottoms from the basin to proximal reef slope. Low sedimentation presumably enhanced shell concentration as well as the development of clusters of superimposed slow-growing organisms, such as Neopycnodonte oysters that are typical of the basin and distal slope settings. Debris-flow beds of mostly disarticulated, fragmented and reoriented moulds of valves intercalate with the autochthonous shell concentrations in the basin and slope deposits as the result of downslope transport of bioclasts from shallower reef areas. Bivalve assemblages in the shallower-water reef palaeonvironments mainly con.sist of moulds of reworked fragments of disarticulated valves. Some crevice-dwellers, cemented and epibyssate forms were preserved in life position in the shelters created by coral colonies and blocks. The percentage of unbroken and articulated shallow endosedimentary bivalves is higher towards the protected inner-lagoon settings, in which Tellina specimens are the most characteristic components. We have identified 52 bivalve species belonging to 38 genera and recorded 19 additional species only identifiable at the generic level in all the sampled reef palaeonvironments.

General Synod of the Scottish Episcopal Church

The General Synod of the Scottish Episcopal Church (SEC) met in virtual form on 10 and 11 June 2021. In his charge to Synod, the Most Rev'd Dr Mark Strange, Primus, encouraged Synod members not to place their light under a bushel. The COVID-19 pandemic had denied people opportunities normally available to them to make their light shine and, at times, the bushel had felt very close. He reminded Synod members that in the valley of the shadow of death one need fear no evil. The evils of child poverty, the plight of refugees and unwarranted attacks on individuals in the public eye were all current evils to be confronted. Despite everything, the place of quiet waters and the comfort of the Shepherd's rod and staff still brought hope and joy, even in a pandemic.

"In Search of Water...! Need to Revise Overreaching Provincial Water Policy"

Sindh is a lower riparian province and its total dependency based on Indus River for water. But since last few decades, Sindh is vulnerable and faces quiet water shortage from upstream overreaching water flow. Even though

Acceptance of COVID 19 Vaccine in India

Sindh is a lower riparian province and its total dependency based on Indus River for water. But since last few decades, Sindh is vulnerable and faces quiet water shortage from upstream overreaching water flow. Even though

The heterogeneous characteristics and their influencing factors of organic matter of saline lacustrine hydrocarbon source rocks

The heterogeneous characteristics and their influencing factors of organic matter are still the research focuses of saline lacustrine hydrocarbon source rocks. This paper examined the heterogeneous characteristics of organic matter richness and type. The effects of tectonic activities, sedimentary facies, climate, biological sources, and preservation conditions on organic matter richness and type were examined in the Yiliping Depression, Qaidam Basin, northwestern China. Organic matter enrichment models for the Yiliping Depression were developed. Total organic carbon (TOC) content, extractable organic matter (EOM) content, and free hydrocarbon and kerogen thermal cracking hydrocarbon yield of mudstones are higher than 0.5%, 0.05% and 0.5 mg/g in the condensed sections and the early stage of high stand systems tracts while lower in other intervals. The heterogeneity of organic matter richness and type in the Pliocene is displayed. With the uplift of the A-erh-chin mountains, influenced by the Himalayan tectonic movement during the Neogene, the sedimentary facies were mainly saline lakes with braided river deltas, and their depocenters gradually migrated eastward. Climatic conditions changed from humid in the lower Pliocene to dry in the middle and upper Pliocene. Multiple water transgressive and regressive cycles formed multiple condensed sections and high stand systems tracts, where enough accommodation space, organic matter supply, favorable preservation conditions resulting from relatively deep and quiet water brought more organic matter accumulation. Mixed input of aquatic algae and terrestrial plants formed type II2 and type III kerogen in the depression, and there are more type II1 and type I hydrocarbon source rocks around lacustrine centers. The saline lacustrine evolution and organic matter accumulation models were developed, showing that the peak saline lacustrine period in the middle Pliocene was the most favorable for organic matter enrichment. The results indicate that there are active hydrocarbon source rocks (TOC content more than 0.4% and reflectance of vitrinite more than 0.5%) from the Neogene around the Jianshishan and Hongsanhan structures, and the Yikeyawuru and Taijinaier structures in the Yiliping Depression.

Mass mortality events of autochthonous faunas in a Lower Cretaceous Gondwanan Lagerst\xe4tte

Mass mortality events are unusual in the Crato Formation. Although mayflies’ accumulations have been previously reported from that unit, they lacked crucial stratigraphic data. Here we provide the first taphonomic analysis of a mayfly mass mortality event, from a layer 285 cm from the top of the Formation, with 40 larvae, and an overview of the general biological community structure of a three meters deep excavated profile. The only other autochthonous taxon observed in the mayfly mortality layer was the gonorynchiform fish Dastilbe. The larvae and fishes were smaller than usual in the layer 285 cm, suggesting that they lived in a shallow water column. Their excellent preservation and a lack of preferential orientation in the samples suggest an absence of significant transport. All mayflies belong to the Hexagenitidae, whose larvae lived in quiet waters. We also recovered allochthonous taxa in that layer indicative of drier weather conditions. Adjacent layers presented crystals and pseudomorphs of halite, suggesting drought and high salinity. In other layers, Dastilbe juveniles were often found in mass mortality events, associated with a richer biota. Our findings support the hypothesis that the Crato Formation’s palaeolake probably experienced seasonal high evaporation, caused by the hot climate tending to aridity, affecting the few autochthonous fauna that managed to live in this setting.

A fine detail physico-chemical depositional model for Devonian organic-rich mudstones: A petrographic study of the Hare Indian and Canol Formations, Central Mackenzie Valley, Northwest Territories

The Hare Indian and Canol Formations, which are part of the Horn River Group in the Northwest Territories, Canada, primarily consist of organic-rich mudstones deposited during the Middle to Late Devonian. The formations were previously considered to represent marine basin fill accumulated in an oxygen-starved distal shelf setting, evidenced by the organic-rich character, pyrite content, and lack of macro-scale bioturbation. The depositional model, paleo‑oxygenation interpretations, and methods of organic carbon preservation presented in this study are in contrast to previous assumptions of the Horn River Group mudstones. Detailed petrographic, sedimentological, and ichnological analyses were carried out on thin sections taken from several cored Horn River Group intervals. These organic-rich mudstone units contain eight distinct microfacies, representing four main sedimentation processes acting on an interpreted distal shelf setting: (1) pelagic suspension settling, (2) plug-like sediment-gravity flows, (3) surge and surge-like low-density turbidity currents, and (4) debrites. Pelagic suspension-settling dominated in distal, quiet waters out of the reach of persistent storm influence. Debrites, plug-like flows, and low-density turbidite processes represent a continuum, wherein storm influence was the dominant driver in sediment delivery. Several morphologically distinct, microscopic biogenic-sedimentary structures (i.e. ichnofossils) have been identified throughout the mudstone intervals, indicative of sediment pore waters that were at least periodically partially oxygenated. Evaluation of total organic carbon content against bioturbation and microfacies interpretation suggest that persistent anoxia was not the dominant factor in organic carbon preservation, but rather a result of a combination of heightened sedimentation and burial rates and possible amplified rates of primary productivity. The results of this study may be applied to evaluations of other organic rich mudstones to enhance paleo-depositional interpretations.

Optimizing the pontoon of a composite dock when changing a ratio of the sides’ length in a reinforced-concrete slab

This paper investigates the local strength of reinforced-concrete slabs in a pontoon of the composite floating dock under uniform hydrostatic load. A refined approach was applied to calculate the reinforced-concrete slabs considering the difference in the mechanical characteristics of concrete exposed to stretching and compression. The length of the zone of fixation that impacts concrete compression and stretching has been determined, which is 0.22 lengths of the short side of the rectangular slab. To this end, preliminary calculations of stresses in slabs made from a non-composite homogeneous material were performed, at different sizes of thickness and ratios of the slabs’ side lengths. A finite-element model of the reinforced concrete slab was built, with its reinforcing elements in the longitudinal and transverse directions. The model accounts for differences in the mechanical characteristics, which are set separately for the compressed and stretched regions of concrete. The stressed-strained state of rectangular reinforced concrete slabs has been estimated for the case of complete immersion of the pontoon in quiet water under the influence of uniform hydrostatic pressure, without taking into consideration possible dynamic loads. When simulating the bottom slabs, the length of the larger side of the supporting contour was taken equal to the distance between the longitudinal walls, based on the structural size of the dock. The length of the short side varied multiple to the longitudinal quad, making it possible to acquire data for a wide range of side length ratios, from 3.3 to 1, most characteristic of ship structures. The compressed and stretched areas of concrete were simulated separately, with the mechanical characteristics of strength and rigidity corresponding to the materials used in the construction of floating docks. The charts of maximum stresses in concrete and slab reinforcement depending on the length of the short side of the supporting contour have been built. This has made it possible to determine the optimum width of the slab, which is equal to 3 m for the considered structure under predefined loading. The applied approach makes it possible to optimize the size of such structures in terms of weight and material consumption

Contact erosion initiated by clay dispersion beneath pavement layers

ABSTRACT Dispersive failures have been reported throughout the world in the recent past. Soils, in which they occur, are vulnerable to erosion even in quiet water. The initiation of dispersive failure below the pavement layers would progress without any sign and the consequences would be more severe than other types of pavement failure. This paper describes a theoretical development of an analytical model to quantify the mass of particle loss due to dispersion failure below the pavement layers and the associated transport and deposition of the detached particles. The analytical model is validated using the experimental results for four different materials with dispersive characteristics. The model calculations are compared with the experimental results and a close correlation is found between the model-calculated and experimental results. The calculated total mass loss per unit area for the most dispersive soil is 1.90 g/cm2, which is very close to the experimental result of 1.72 g/cm2. The study indicates that the mass loss in the first water contact is significantly greater than those in the subsequent cycles for all the materials in the analytical and experimental results. Also, the calculated total mass loss is very close to the experimental results.

Synchronized moulting behaviour in trilobites from the Cambrian Series 2 of South China

The study of moulting behaviour in the fossil record is relatively well known in arthropods and this is especially true for trilobites. Nevertheless, while studies focusing on the style of moulting in social and semi-social groups of modern animals (e.g. arthropods) are common, very few works investigate moulting adaptations in deep time. Here we report a trilobite assemblage from the Cambrian Series 2 “Tsinghsutung” Formation of South China. Around 850 specimens were used for this study from three different levels across one section near Balang (SE Guizhou Province, South China). These levels preserve numerous trilobite clusters in some cases containing around 400 individual specimens. Up to four species have been found in these clusters, but two species are more common. Trilobite clusters bear a high percentage of disarticulated specimens that we interpret as moults. Additionally, measurements of bioclast orientation and the dorsoventral attitude suggests very quiet water conditions followed by rapid burial events, prior to scavenger disturbance. Together, this indicates that the fossil assemblages were a result of a biological phenomenon rather than mechanical processes, allowing us to interpret the position of the fossil parts as different moulting configurations. Since the trilobite assemblage seems to be in situ, the large number of exuviae suggests a local place of migration. This was triggered by the need for group protection while moulting, which is suggestive of gregarious behaviour, possibly synchronized. These trilobites from the Cambrian Epoch 2, Age 4 constitute one of the earliest known gregarious community of trilobites and has important implications for understanding the ecology of this group during their emergence in the Cambrian.

Landscape and infrastructure preferences of recreational rowers in Germany

The purpose of this study was to determine landscape and infrastructural preferences of recreational rowers in Germany. For this purpose, a two step study design was developed. First, a qualitative survey and visitor employed photography were conducted. Based on the results, a quantitative online survey was conducted and a geographic information system was used to determine waterway usage. Recreational rowers prefer especially natural water landscapes with versatile bank vegetation as well as spacious waters with mountain vistas. Preference increases through smooth, clean and quiet waters. As to infrastructure, suitable jetties as well as safe water locks are crucial. Local hot spots for recreational rowing are distributed all over Germany. National secondary waterways are particularly preferred. Management Implications•For waterways that already have a high volume of use, recreational infrastructure quality should be improved by including the needs of recreational rowers. In particular with regard to jetties and locks. This applies primarily to national secondary waterways.•Natural landscapes are preferred by recreational rowers and by other water-based activities. Banks and surrounding landscape should be renatured if necessary to increase recreational potential.•When developing recreational concepts for waterways, all stakeholders must be involved at an early stage to consider special interests and to achieve acceptance.