River Branches Research Articles

Nutrients loads at Shatt Al-Arab river in Basrah city, Iraq

The study included the nitrates, phosphates loads and some properties of water quality in the Shatt Al-Arab River at Basra city center . There were used to identifying the state of water and nutrient movement in this part of the River starting from the Shilha location north of Al-Hartha to ​​Al-Bahadriyah north of Abu Al-Khasib, which represents the section that contains dense human population at Basra city center. Fourteen sampling stations were selected within the study area during the summer and winter periods, as well as during the morning and evening at the same day.
 The study showed that the phosphate and nitrate salts have not transfer out of this river section. Also there were no significant impact of the side river branches on the water quality of the Shatt al-Arab River because of the low discharges from these branches compared to discharge of the main Shatt al-Arab River.

Gravel Mining Activity Impact on Riverbed Erosion and Bridge Foundation Stability

Geomorphological processes pose a risk that deserves attention and planning to avoid that, especially in the section near to east of Tuz bridge. This section of the valley facing a dramatic increase in gravel excavation and sorting of aggregates, consequence led to a change in the pattern of river branches flow from an anabranching river to a single-channel river, which led to a concentration of river discharge during floods. On 9th December 2018, Tuz Bridge was failed due to a heavy rainstorm three days preceding the failure event. The current study aims to conduct a field survey of all the human activities in the study area to assess river changes from remote sensing data the amount of runoff and river peak discharge based on rainfall data using SCS-CN method. In this study, ArcGIS, ArcGIS Earth, Google Earth, and WMS software are incorporated in the data analysis. The revealed results indicate the severe modification of valley morphology and converting the river pattern to flow during flood within a single channel with flow speed exceeded the critical velocity to induce vertical erosion of gravel and sands under the foundations of the bridge and causing the displacement and settlement of the bridge. The study recommends the local administration prevent gravel mining from the river valley at the upstream area of the bridge

Latest Pleistocene–Holocene Incremental Slip Rates of the Wairau Fault: Implications for Long‐Distance and Long‐Term Coordination of Faulting Between North and South Island, New Zealand

AbstractWe use high‐resolution lidar microtopographic data and luminescence dating to constrain incremental Holocene–latest Pleistocene slip rates for the Wairau fault, a major dextral strike‐slip fault in the Marlborough Fault System, South Island, New Zealand. Our data come from two closely spaced study areas along the structurally simple, central portion of the fault: The well‐known Branch River terrace flight, and a previously undated series of offset risers and channel features several km to the east that we refer to as the Dunbeath site. Field work and mapping using lidar‐derived topography yields revised or novel measurements of nine fault offsets. We date those features using a post‐IR50‐IRSL225 infrared stimulated luminescence dating method, and a stratigraphically informed Bayesian age model. The dated slip history of the Wairau fault is further constrained using newly cataloged offset measurements collected along a ∼35 km stretch of the fault, and available paleoseismic data. Incremental slip rates are precisely computed using a Monte Carlo resampling scheme. Our results provide a nearly earthquake‐by‐earthquake record of incremental slip, with pronounced variations in incremental slip rate spanning multiple millennia and tens of m of slip. These extreme, multi‐millennial variations in fault slip rate have basic implications for earthquake occurrence, plate boundary lithosphere behavior, and probabilistic seismic hazard assessment.

Modelling early medieval flood-induced breaching of a coversand ridge in the IJssel valley, Rhine delta, the Netherlands

Connecting geologically mapped data to numerical modelling can help in understanding river landscape evolution. This study focuses on flood-induced breaching of the coversand ridge in the IJssel valley floodplain (Rhine delta, the Netherlands). The development of the breach would explain why this river branch came into existence in early medieval times. Prior to the breaching, the coversand ridge formed a barrier for the Rhine River to discharge towards the north. A palaeoflood model was coupled to a local sediment transport model to predict sediment transport rates in two competing coversand ridge breaches. The results show that the breach at the current IJssel River location was expected to expand earlier and faster in time for various upstream discharge waves and initial breach dimensions. This provides quantitative argumentation for the IJssel river avulsion case to have been triggered by the breaching of the coversand ridge during a large palaeoflood.

Thermokarst Lagoons: A Core-Based Assessment of Depositional Characteristics and an Estimate of Carbon Pools on the Bykovsky Peninsula

Permafrost region subsurface organic carbon (OC) pools are a major component of the terrestrial carbon cycle and vulnerable to a warming climate. Thermokarst lagoons are an important transition stage with complex depositional histories during which permafrost and lacustrine carbon pools are transformed along eroding Arctic coasts. The effects of temperature and salinity changes during thermokarst lake to lagoon transitions on thaw history and lagoon deposits are understudied. We analyzed two 30-m-long sediment cores from two thermokarst lagoons on the Bykovsky Peninsula, Northeast Siberia, using sedimentological, geochronological, hydrochemical, and biogeochemical techniques. Using remote sensing we distinguished between a semi-closed and a nearly closed lagoon. We (1) characterized the depositional history, (2) studied the impact of marine inundation on ice-bearing permafrost and taliks, and (3) quantified the OC pools for different stages of thermokarst lagoons. Fluvial and former Yedoma deposits were found at depth between 30 and 8.5 m, while lake and lagoon deposits formed the upper layers. The electrical conductivity of the pore water indicated hypersaline conditions for the semi-closed lagoon (max: 108 mS/cm), while fresh to brackish conditions were observed beneath a 5 m-thick surface saline layer at the nearly closed lagoon. The deposits had a mean OC content of 15 ± 2 kg/m3, with higher values in the semi-closed lagoon. Based on the cores we estimated a total OC pool of 5.7 Mt-C for the first 30 m of sediment below five mapped lagoons on the Bykovsky Peninsula. Our results suggest that paleo river branches shaped the middle Pleistocene landscape followed by late Pleistocene Yedoma permafrost accumulation and early Holocene lake development. Afterward, lake drainage, marine flooding, and bedfast ice formation caused the saline enrichment of pore water, which led to cryotic talik development. We find that the OC-pool of Arctic lagoons may comprise a substantial inventory of partially thawed and partially refrozen OC, which is available for microbial degradation processes at the Arctic terrestrial-marine interface. Climate change in the Arctic leading to sea level rise, permafrost thaw, coastal erosion, and sea ice loss may increase the rate of thermokarst lagoon formation and thus increase the importance of lagoons as biogeochemical processors of former permafrost OC.

Co-variations of climate and silicate weathering in the Nile Basin during the Late Pleistocene

We have investigated provenance and weathering proxies of the clay-size sediment exported from the Nile River basin over the last 110,000 years. Using neodymium isotope composition of sediments from both the Nile Deep Sea-Fan and Lake Tana, we show that the Nile River branches draining the Ethiopian Highlands have remained the main contributors of clays to the Nile delta during the Late Quaternary. We demonstrate that fluctuations of clay-size particle contribution to the Nile Delta are mainly driven by orbital precession cycle, which controls summer insolation and consequently the African monsoon intensity changes. Our results indicate that - over the last 110,000 years – the proportion of clays coming from Ethiopian Traps fluctuates accordingly to the intensity of the last 5 precession cycles (MIS 5 to MIS 1). However, there is a threshold effect in the transport efficiency during the lowest insolation minima (arid periods), in particular during the MIS3. Several arid events corresponding to the Heinrich Stadial periods are associated with small or negligible clay source changes while chemical weathering proxies, such as δ7Li, Mg/Ti and K/Ti, vary significantly. This suggests a straightforward control of weathering by hydro-climate changes over centennial to millennial timescales. Our data also suggests a significant but more progressive influence of the temperature decrease between 110kyr and 20kyr. Taken altogether, the observed tight coupling between past climate variations and silicate weathering proxies leads us to conclude that precipitation changes in northeast Africa can impact soil development over a few hundred years only, while the influence of temperature appears more gradual.

Trunk river and tributary interactions recorded in the Pleistocene–Holocene stratigraphy of the Po Plain (northern Italy)

AbstractTributary rivers can contribute significantly to alluvial‐plain construction by supplying large volumes of clastic material. Their relation to the main axial river strongly influences sediment deposition and preservation. The Po Plain is fed by the Po River and a dense network of transverse tributaries draining the nearby Alpine and Apennine chains. Stratigraphic, sedimentological, petrographic and geochemical analyses on 38 cores permitted detailed differentiation of Po and Apennine sedimentary units. Po River deposits are vertically stacked channel‐belt sand bodies with high contents of quartz–feldspar and metamorphic rock fragments, combined with high chromium levels. These sand bodies, 20 to 30 km wide, are replaced southward by finer‐grained deposits that represent the distal Apennine tributary‐rivers system. Apennine sands, confined in narrow ribbons, show lower quartz–feldspar contents, abundant sedimentary lithics and lower chromium levels. In the last 870 kyr, the boundary between the Po and the Apennine sediment delivery systems shifted along a north–south axis in response to distinct controlling factors. A 20 km northward shift of the Po channel belt, possibly related to a tectonic event, is recorded across a regional unconformity dating to the Marine Isotope Stage 12/11 transition. High sediment supply rates during glacial‐lowstand periods widened the Po channel belt southward towards the Apennine domain for a few kilometres. The Last Glacial Maximum channel‐belt sand body, 30 km wide and 40 m thick, progressively narrowed northward after the glacial culmination. During the Holocene, channel patterns became avulsive and distributive. Narrow channel belts (<3 km) formed along the Po River branches, and abundant swamp and poorly drained‐floodplain muds were preserved in interfluvial areas. Activation and deactivation of the Po branches resulted in sharp narrowing and widening of the area available for Apennine‐rivers sedimentation. This work provides insights into tributary‐trunk river relations which control grain‐size distribution and compositional characters of subsurface deposits.

Dating and provenancing the Woman with lantern sculpture – A contribution towards attribution of Netherlandish art

• Interdisciplinary study to ascertain production date and place of an oak sculpture • X-ray CT images provided tree-ring patterns on the widest sections and aided dating • Dendrochronology suggests differentiated wood supply in Netherlandish workshops • Determining wood provenance can assist in attribution of Netherlandish works of art • Imaging science is the future of non-invasive research of historical art objects Studying the wood of art objects such as sculptures, panel paintings and furniture can be crucial to elucidate their chronology and production centre. Here we present an approach that considers the provenance of the wood and its potential availability in different areas as a means to identify the provenance of wooden art objects. We illustrate this approach with an interdisciplinary study aimed to determine the date and provenance of the Woman with lantern , a carved altar fragment from the Rijksmuseum's collections (Amsterdam, The Netherlands). The origin of this object is undocumented, but based on stylistic and iconographic features its provenance was proposed to be the altarpiece of Rennes cathedral (France), carved in Antwerp (Belgium) around 1520 C.E.. However, doubts arose when curators tested the potential fit of the sculpture in that altarpiece and could not find a neat match. Dating and provenancing the wood of the sculpture by standard dendrochronological means failed to produce a date, and comparison of the tree-ring pattern from the sculpture with those of the sculptures from Rennes altarpiece delivered no results either, supporting the suspicion that the Woman with lantern belonged elsewhere. In 2019, X-ray computed tomography (CT) provided digital cross-sections throughout the sculpture and a longer tree-ring series was obtained. This time, the outermost ring was dated to the year 1487 C.E.. The tree was estimated to have been cut after 1495 C.E., indicating a likely production in the first quarter of the 16th century. The origin of the timber in the eastern Netherlands/northwest Germany, combined with empirical evidence about timber availability in various regions of the Low Countries at that time, suggests that the sculpture was made in a workshop located north of the Rhine in the (current) Netherlands, rather than Antwerp. This research has led to the hypothesis that workshops north and south of the Rhine river branches in the Low Countries were supplied by forests located in different areas. If proven correct, establishing the wood provenance will assist in determining the origin of Netherlandish works of art from the late-Gothic and Northern Renaissance periods.

Modelling framework for flow, sediments and nutrient loads in a large transboundary river watershed: A climate change impact assessment of the Nemunas River watershed

This study provides an in-depth analysis of the Nemunas River watershed, situated in the Baltic Sea basin, and possible future changes to the stream flow, hydrologic regime, sediment (SS), Total Nitrogen (TN) and Total Phosphorus (TP) load from the river to the Curonian Lagoon under different climate change scenarios using high-resolution modelling. The sub-regions of the watershed, represented by sub-basins of the Nemunas River tributaries and the main river branch, were modelled using the Soil and Water Assessment Tool (SWAT). The model setup was performed using the developed customizable MATLAB scripts for an advance Hydrologic Response Unit configuration and a hillslope delineation procedure. The modelling framework was used to assess the climate changes in the watershed under two future scenarios: RCP4.5 and RCP8.5, using the projected changes to precipitation, temperature, and carbon dioxide concentrations for the near-term (up to 2050) and long-term period (up to 2100) compared to the baseline period (1995–2010). The projections show that the annual long-term trends for flow, depending on the scenario, are small or not existing. Even if there is no visible change in trends over the years, inter-annual changes on flow, sediment and nutrient load will occur. The findings of the study suggest that the conditions of the RCP4.5 are likely to be more “wet”, whereas RCP8.5 will likely be “drier”. Most shifts will occur in the winter season, especially in January and February. A decrease in snow cover across the watershed, together with the greater frequency of soil freeze-thaw cycles can weaken the nutrient retention of soils and increase nitrogen and phosphorus losses. Coupled with the increased flows in winter, the projected nutrient load changes during winter season indicate a two-fold increase in sediment, up to 42% and 62% in TN and TP load to the Nemunas River and subsequently, to the Curonian lagoon.

THE INFLUENCE OF SEMBAYAT WEIR ON SEDIMENT TRANSPORT RATE IN THE ESTUARY OF BENGAWAN SOLO RIVER, INDONESIA

This research is aimed to assess the sediment transport rate under different conditions of estuary geometry by comparing the situations before and after the construction of Sembayat Weir. Sediment concentration, flow velocity, and temperature were obtained via field investigation from October 2016 to September 2017. River discharge and tidal discharge phenomenon are analyzed in the estuary, which affect hydraulic head changes. The HEC-RAS model was used for numerical modelling simulation of the hydrodynamics. The results revealed that the sediment transport rate increased under the influence of erosion in the river branches. BH2 and BH3 were the observation sites located before and after the tributary junction. Those location present the sediment transport rates decreased by 30% and 26%, respectively, in the rainy season because after weir construction. The results agree with previous research results in that sediments were deposited around the estuary weir. Meanwhile, in the river branches, a higher sediment transport rate was observed because of the tidal current that provided sediment transport over a longer term in the dry season. The findings extend the knowledge on the influence of Sembayat Weir on sediment transport rate characteristics with respect to seasonal changes.

Korelasi Karakteristik Fisik Rumah dan Tingkat Kerentanan Sosio-Ekonomi di Tepian Sungai Kapuas Pontianak

Kampung Dalam Bugis is an area in Pontianak City located in the Kapuas River and the Landak River branch. This area is a kampung and settlement that marked the establishment of Pontianak City. Kampung Dalam Bugis Village is located on the bank of a river, impacting flood disaster vulnerability. Therefore, it is necessary to study the correlation between the physical characteristics of the house and the level of socio-economic vulnerability. This study aims to analyze the correlation between the physical characteristics of the houses and the level of socio-economic vulnerability at the riverbanks. The analysis used to assess socio-economic vulnerability is scoring from data collected from interviews and filling out questionnaires. The study used to determine the relationship between the house's physical characteristics to indicators of socio-economic vulnerability is chi-square. The assessment of the community's socio-economic vulnerability on the banks of the Kapuas River consists mostly of high vulnerability classes. Chi-square analysis shows that indicators of socio-economic vulnerability such as the head of the family's educational level have a relationship to the house's characteristics, such as the type of house and the area of the house. This initial research still needs to be developed, such as using logistic regression analysis. There is more vital evidence that the information can be used as a basis for determining or at least as a validator for indicators of socio-economic vulnerability. Physical information of the house is easier to find data through observation and even image interpretation.

Downscaling With an Unstructured Coastal-Ocean Model to the Goro Lagoon and the Po River Delta Branches

The Goro Lagoon Finite Element Model (GOLFEM) presented in this paper concentrates on the high-resolution downscaled model of the Goro Lagoon, along with five Po river branches and the coastal area of the Po delta in the northern Adriatic Sea (Italy) where crucial socio-economic activities take place. GOLFEM was validated by means of validation scores (bias – BIAS, root mean square error – RMSE, and mean absolute error – MAE) for the water level, current velocity, salinity and temperature measured at several fixed stations in the lagoon. The range of scores at the stations are: for temperature between −0.8 to +1.2°C, for salinity from −0.2 to 5 PSU, for sea level 0.1 m. The lagoon is dominated by an estuarine vertical circulation due to a double opening at the lagoon mouth and sustained by multiple sources of freshwater inputs. The non-linear interactions among the tidal forcing, the wind and the freshwater inputs affect the lagoon circulation at both seasonal and daily time scales. The sensitivity of the circulation to the forcings was analyzed with several sensitivity experiments done with the exclusion of the tidal forcing and different configurations of the river connections. GOLFEM was designed to resolve the lagoon dynamics at high resolution in order to evaluate the potential effects on the clam farming of two proposed scenarios of human intervention on the morphology of the connection with the sea. We calculated the changes of the lagoon current speed and salinity, and using opportune fitness indexes related to the clams physiology, we quantified analytically the effects of the interventions in terms of extension and persistence of areas of the clams optimal growth. The results demonstrate that the correct management of this kind of fragile environment relies on both long-term (intervention scenarios) and short-term (coastal flooding forecasts and potential anoxic conditions) modeling, based on a flexible tool that is able to consider all the recorded human interventions on the river connections. This study also demonstrates the importance of designing a seamless chain of models that are capable of integrating local effects into the coarser operational oceanographic models.

Variability in water chemistry in the Lower Mekong Basin: Considerations for fish life history reconstruction

Spatial and temporal variation of nine elements (Ba, Ca, Cu, Mg, Mn, Na, Se, Sr, and Zn) and some additional environmental parameters (salinity, water levels, and conductivity) were examined over two 2,000 km along the length of the main Mekong River channel from Luang Prabang in Northern Lao PDR to the Mekong Delta in Vietnam. Longitudinal profiles of some dissolved elemental concentrations varied significantly along the river channel. For example, Sr concentration in marine water was up to 83 times higher than in fresh water. By contrast, Ba concentration was around 4 times higher in fresh water than in marine water, but was significantly influenced by inflows from major tributaries in Cambodia (dilution effects). We found dissolved Ba was elevated in low salinity. Furthermore, Sr concentration was more variable than Ba, especially in the Mekong Delta due to different tidal influences in each of the Delta branches. Selenium was only present along the coast and one river branch in the delta. The variation in water chemistry of the Mekong main channel identified through this study provides information that can be used in the interpretation of regional fish movements using otolith chemistry, including across the freshwater, estuarine and marine interface. Accurate interpretation is essential given the Lower Mekong Basin has a high biodiversity that is under threat from rapid development, and substantial knowledge gaps exist on the life history requirements of numerous fish species.

The July 2020 Rainfall-Induced Sediment Disasters in Kumamoto Prefecture, Japan

On July 4, 2020, heavy rainfall was observed in the southern part of Kumamoto Prefecture and the northern part of Kagoshima Prefecture. Due to heavy rainfall, floods and sediment disasters such as collapses and debris flows occurred predominantly in the Kuma River basin of Kumamoto Prefecture. We conducted field investigations at four sites in Ashikita Town and Tsunagi Town, Kumamoto Prefecture, where collapses and debris flows caused deaths. We also conducted field investigations in the Kawauchi River branch of the Kuma River, where vast amounts of sediment discharge caused damage to houses. The objectives of these investigations were to clarify the situation and mechanism of the disasters and to propose procedures to recover from the disasters. This report briefly summarizes the results of these investigations.

English

Abstract Crayfish are an aquatic fauna of conservation concern, yet regional studies are lacking on zoogeography and life history. We compared recent and historical species distribution data and assessed conservation standings of native and nonindigenous crayfish of the Potomac River Basin in West Virginia. From 2007–2011, a total of 1764 crayfish were collected from 159 sites. Data collection included species abundance, morphometrics, and life history parameters. Percentages of the number of individuals of each species of the total catch were 36.3% (Cambarus bartonii), 34.6% (Faxonius obscurus), 23.4% (Faxonius virilis), 3.6% (Procambarus cf. zonangulus) and 2.0% (Cambarus carinirostris). Cambarus bartonii was present throughout the drainage, F. obscurus was collected primarily from the North Branch, South Branch, and Cacapon river watersheds, and C. carinirostris was only collected in the South Branch watershed. Two nonnative species, F. virilis and P. cf. zonangulus, were only present in tributaries downstream of the Cacapon River watershed. Spinycheek crayfish (Faxonius limosus) were not collected during our survey, which suggests its possible extirpation from the West Virginia portion of its range. Our zoogeographic and life history data could serve as a baseline for future conservation-oriented monitoring efforts of the Potomac River watershed.

Channels of the glacial river Jökulsá á Breiðamerkursandi

The glacial river Jökulsá á Breiðamerkursandi drains the Jökulsárlón tidal lagoon (27 km2), in Southeast Iceland. Despite being the shortest glacial outlet (0.6 km), it is among the most voluminous rivers in Iceland, with an estimated average drainage of 250–300 m3/s and has doubled its volume at peak runoff. Until a bridge was established, this was one of Iceland’s most infamous river and for travellers, cruising on horseback, the greatest obstacle to cross on the main road. The river began shaping its present channel in the late 19th century but was not permanently settled until the mid-20th century. Before that it used to wander around the fan, occasionally in several branches, or as a single heavy moving water. In this paper we present a map of its known runoffs and channels that were formed in the 19th and 20th centuries. Few channels were digitized from old maps, but several of those were identified and recorded by the late Flosi Björnsson (1906–1993), a farmer from the Kvísker, who guided travellers across the river before the bridge was built. The Breiðamerkurjökull outlet glacier of Vatnajökull, Southeast Iceland, advanced 10–15 km during the Little Ice Age. During the LIA advance the wide fan shaped shore in front of Breiðamerkurjökull gradually extended outward by >1 km, mainly due to sediment deposition by the Jökulsá river and few other temporal glacial river branches. At the turn of the 20th century the outlet glacier started to retreat slowly and in the 1930s terminal lakes were formed. With the formation of the Jökulsárlón tidal lagoon river dumping at the shore terminated and was replaced by a progressive coastal erosion. Currently ca. 0.9 km has eroded off the coast since the 1930s. A 0.65 km wide strip now remains between the coast and Jökulsárlón tidal lagoon, where the Jökulsá river and the remains of its former runway channels are located.

Lithological control on scour hole formation in the Rhine-Meuse Estuary

River deltas commonly have a heterogeneous substratum of alternating peat, clay and sand deposits. This has important consequences for the river bed development and in particular for scour hole formation. When the substratum consists of an erosion resistant top layer, erosion is retarded. Upon breaking through a resistant top layer and reaching an underlying layer with higher erodibilty, deep scour holes may form within a short amount of time. The unpredictability and fast development of these scour holes makes them difficult to manage, particularly where the stability of dikes and infrastructure is at stake.In this paper we determine how subsurface lithology controls the bed elevation in net incising river branches, particularly focusing on scour hole initiation, growth rate, and direction. For this, the Rhine-Meuse Estuary forms an ideal study site, as over 100 scour holes have been identified in this area, and over 40 years of bed level data and thousands of core descriptions are available. It is shown that the subsurface lithology plays a crucial role in the emergence, shape, and evolution of scour holes. Although most scour holes follow the characteristic exponential development of fast initial growth and slower final growth, strong temporal variations are observed, with sudden growth rates of several meters per year in depth and tens of meters in extent. In addition, we relate the characteristic build-up of the subsurface lithology to specific geometric characteristics of scour holes, like large elongated expanding scour holes or confined scour holes with steep slopes. As river deltas commonly have a heterogeneous substratum and often face channel bed erosion, the observations likely apply to many delta rivers. These findings call for thorough knowledge of the subsurface lithology, as without it, scour hole development is hard to predict and can lead to sudden failures of nearby infrastructure and flood defence works.

Rotary Spectral Analysis for Directional Time Series: Seasonal Variation of Wind Speed on a Subtropical Island near the Western Pacific Ocean

Directional or vector time-dependent observations, such as the flow at a river branch, streamflow, lake flow, ocean currents, or wind data, are commonly observed in the environment. Traditionally, a rose diagram can be used to summarize the possible main orientation using all the data in the time domain. However, it cannot indicate the significant variation in the specific frequency bands that may show dominant periodic fluctuations. Assessment of directional time series often requires the identification of significant components in the specific frequency bands for not only the magnitude but also the orientation. The rotary pattern, main orientation, and magnitude of directional time series in the frequency domain for five sets of seasonal wind velocity observed at the northern, southern, eastern, and western coast of the subtropical island Taiwan and Taiwan Strait have been demonstrated. It shows that the representative pattern is clockwise, counterclockwise, or near rectilinear, and semidiurnal and diurnal components are significant in the frequency domain for most stations. The most important research innovation suggests that the use of rotary spectral analysis in the frequency domain to effectively assess the orientation and magnitude of directional time series, such as hydrological, coastal, or environmental observations, has become feasible.

Features of the restoration of biological communities after the technogenic transformation of the estuary area of the Pregolya River (the Baltic Sea basin)

The structural parameters of plankton, benthos and macrophytes after large-scale technogenic transformation of the mouth area of the river were studied. Pregolya. A decrease in the species richness and area of growth of macrophytes, a simplification of the structure of communities was noted. The renewal of plant communities in the places of their origin was recorded, primarily due to the species resistant to biogenic pollution. A decrease in the abundance of submerged species with wide leaves was revealed, which is an indicator of an increase in water turbidity. The species were found in the phyto- and zooplankton community, living in conditions of an increased content of nutrients and suspended matter. There was no significant decrease in the species diversity of summer plankton and benthos, and the quantitative indicators are comparable with the data before the work. A feature of the restoration of the zooplankton and benthic community was the appearance of brackish-water species in the river branches, which were not previously recorded there, incl. alien species of mollusks and polychaetes.

Genetic diversity and differentiation of cytochrome oxidase subunit I (COI) gene of Rasbora lateristriata bleeker in different habitat

Rasbora lateristriata is a freshwater fish that has small size and schooling fish in the shallow river. This fish is called Nyalian by the people in Bali. The population of Rasbora lateristriata has decreased at upstream in Sungi river that already lightly polluted. The genetic diversity of Rasbora lateristriata based on the Cytochrome Oxidase subunit I gene as a marker will be detected in the upstream, branch river, middle stream and downstream of the Sungi river. The method that used is the polymerase chain reaction (PCR) with two primers are Fish-BCL (forward) and Fish-BCH (reverse) were followed by sequencing using the method of Sanger sequencing to obtain its nucleotide sequences. Genetic diversity was analyzed using Mega 5.2 version. Nucleotide composition of Rasbora lateristriata are Thymine 29.8%, Cytosine 25.8 to 26.2%, Adenine 26.0% and Guanine 18.5-18.6% with total nucleotide are 633 to 682. The branch of the river, middle stream and downstream which the genetic diversity of locus COI experienced a change of nucleotide at the sixth base, Thymine (T) is replaced with Cytosine (C). Substitution Thymine to Cytosine is occurring on a polluted part of the river that may be caused by the parameters of the water quality.