Influence of Zooplankton and Environmental Factors on Clear-Water Phase in Lake Paldang, South Korea

Lake Paldang is a complex water system with both fluvial and lacustrine characteristics and the largest artificial dam lake in South Korea. In this study, the different occurrence patterns and causes of the clear-water phase (CWP) were investigated using water quality and hydrological factors at four sites in Lake Paldang. Among the environmental and other factors associated with CWP occurrence, secchi depth and turbidity exhibited significant correlations with precipitation, hydraulic retention time (HRT), and individual and relative abundance (RA) of zooplankton (Cladocera) (p < 0.01). Hence, a change in the HRT because of precipitation could alter the CWP. The Cladocera individuals and RA showed significant correlations with the water temperature, indicating that the emergence of Cladocera in spring as the water temperature rises could cause the CWP. Sensitivity assessments conducted using Bayesian models demonstrated different CWP occurrence sensitivity relationships for the river-type, lake-type, and shallow and deep sites. Turbidity, secchi depth, and zooplankton factors also showed sensitive relationships with CWP occurrence for all sites. The sensitivity to precipitation and HRT was higher in the river-type sites. The lake-type sites, with common Cladocera emergence and long HRT, favored CWP occurrence. Thus, CWP occurrence was dependent on the site characteristics and climate conditions.

Rediscovering, Reevaluating, and Restoring Lost River-Wetland Corridors

River-wetland corridors form where a high degree of connectivity between the surface (rheic) and subsurface (hyporheic) components of streamflow creates an interconnected system of channels, wetlands, ponds, and lakes. River-wetland corridors occur where the valley floor is sufficiently wide to accommodate a laterally unconfined river planform that may feature morphologically complex, multi-threaded channels with vegetated bars, islands, and floodplains. River-wetland corridors can develop anywhere there is valley expansion along a drainage network, from the headwaters to estuaries or deltas, and they are found across all latitudes and within all biomes and hydroclimates. River-wetland corridors may be longitudinally continuous but are commonly interspersed with single-thread reaches in narrower portions of the valley. The development and persistence of river-wetland corridors is driven by combinations of geologic, biotic, and geomorphic processes that create a river environment that is diverse, heterogeneous, patchy, and dynamically stable, and within which patterns of flow, sediment features, and habitats shift continually. Hence, we describe these polydimensional river corridors as “kaleidoscope rivers.” Historically, river-wetland corridors were pervasive in wide, alluvial valley reaches, but their presence has been so diminished worldwide (due to a diverse range of anthropogenic activities and impacts) that the general public and even most river managers are unaware of their former pervasiveness. Here, we define river-wetland corridors as a river type; review paleoenvironmental and historical records to establish their past ubiquity; describe the geologic, biotic, and geomorphic processes responsible for their formation and persistence; and provide examples of river-wetland corridor remnants that still survive. We close by highlighting the significance of the diverse river functions supported by river-wetland corridors, the consequences of diminution and neglect of this river type, and the implications for river restoration.

Things we can do now that we could not do before: Developing and using a cross-scalar, state-wide database to support geomorphologically-informed river management

A fundamental premise of river management is that practitioners understand the resource they are working with. In river management this requires that baseline information is available on the structure, function, health and trajectory of rivers. Such information provides the basis to contextualise, to plan, to be proactive, to prioritise, to set visions, to set goals and to undertake objective, pragmatic, transparent and evidence-based decision making. In this paper we present the State-wide NSW River Styles database, the largest and most comprehensive dataset of geomorphic river type, condition and recovery potential available in Australia. The database is an Open Access product covering over 216,600 km of stream length in an area of 802,000 km2. The availability of the database presents unprecedented opportunities to systematically consider river management issues at local, catchment, regional and state-wide scales, and appropriately contextualise applications in relation to programs at other scales (e.g. internationally)–something that cannot be achieved independent from, or without, such a database. We present summary findings from the database and demonstrate through use of examples how the database has been used in geomorphologically-informed river management. We also provide a cautionary note on the limitations of the database and expert advice on lessons learnt during its development to aid others who are undertaking similar analyses.

Physical Modelling of Roll and Pitch Motions of Travelling or Stationary Ship in Large-Scale Landslide-Generated Waves

Large-scale landslides often occur in river-type reservoirs, and landslide-generated waves affect navigation channels and the navigation of ships. Thus, such waves cause widespread regional disasters. This study establishes a mechanical model of landslide-generated waves via field investigations and data collection, reveals the mechanism and process of landslide-generated waves, and investigates the propagation characteristics of landslide-generated waves along a sloping wave. The feasibility of the model is verified via (i) regularity analysis, (ii) comparative analysis of the effect of landslide-generated waves of mountain river channel reservoirs on the movement characteristics of navigation vessels and stationary vessels, (iii) deviation from the equilibrium position, and (iv) an in-depth study of the influence of large-scale landslide-generated waves on ships in different navigation positions in a river channel. Countermeasures are proposed for a sailing ship to tackle a sudden landslide-generated wave; these measures can provide a theoretical basis for ships to sail safely through large-scale landslide-generated waves.

Zpráva o záchranném výzkumu mladopaleolitického sídliště v Hlinsku u Lipníka nad Bečvou

This article presents the results of a 2019 rescue excavation of an Upper Palaeolithic settlement at Kouty III in Hlinsko u Lipníka in Central Moravia. The excavation took place due to a planned enlargement of the local greywacke mine. Lithic artefacts were found in Quaternary sediments redeposited by slope processes. The density of artefacts was quite low; therefore, it was not possible to recover them using a standard archaeological excavation and most of them were collected on the mounds of dirt beside the trenches excavated by a mechanical excavator, or during an excavation of the Eneolithic barrows situated in the south-western part of the site. A total of 106 lithic pieces were found during this excavation. Eighteen of the artefacts lacked a patinated surface, thus they were attributed to the Eneolithic period. A collection of 88 patinated lithics was classified as Aurignacian based on technological and typological characteristics. Most of the artefacts were made on erratic flint, however radiolarite, quartzite, spongolite and Moravian Jurassic chert were present as well. The technology was based on production of blades and bladelets from Upper Palaeolithic prismatic cores. These bladelets could have been used as components of composite tools. One tool set is similar to the neighbouring site Kouty I (Škrdla 2007) and consists of nine burins, three splintered pieces, one thick end scraper and two tool fragments. A bifacial triangular point that was found at Kouty I (Demidenko et al. 2018) and at several other surface sites in the surrounding area, were not found here. Despite this fact it is possible to classify this site as Evolved Aurignacian of the so-called Morava River type (Klíma 1978), which is quite common in this region.

Зообентос Дубоссарского и Кучурганского водохранилищ

The aim of the research is to compare the structure and quantitative indicators of the zoobenthos of two reservoirs that are geographically close to one another and differ in their hydroecological features. On the territory of Moldova are two contrasting reservoirs - the Dubossary reservoir of river type and the Cuciurgan reservoir-cooler Moldovan hydroelectric power station lake type with reverse cooling system. Their hydrological features differ mainly by the type of reservoir, the thermal regime and the mineralization of water. The qualitative composition and quantitative development of the main zoobenthos groups depend on these features. In the zoobenthos of both reservoirs is dominated oligochaetes and chironomids. Oligochaetes predominate numerically in the more eutrophicated Kuchurgan reservoir. Polychaetes are more numerous in the reservoir with an increased level of mineralization. The density of amphipods on silty soils is higher in ponds with a higher number of Zebra mussel. A high degree of mineralization of the Kuchurgan reservoir contributed to the emergence of a new invasive species - the North American crab Rhithropanopeus harrisi.